KLA TENCOR CORP
S-3, 1998-05-12
OPTICAL INSTRUMENTS & LENSES
Previous: REGENT TECHNOLOGIES INC, 8-K, 1998-05-12
Next: CERPLEX GROUP INC/DE, 10-Q, 1998-05-12



<PAGE>   1
      As filed with the Securities and Exchange Commission on May 12, 1998
                                                    Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                                    FORM S-3
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933


                             KLA-TENCOR CORPORATION
             (Exact name of registrant as specified in its charter)


           DELAWARE                                      04-2564110
   (State of incorporation)                 (I.R.S. Employer Identification No.)

                                 160 RIO ROBLES
                           SAN JOSE, CALIFORNIA 95134
                                 (408) 875-3000
  (Address, including zip code, and telephone number, including area code, of
                    registrant's principal executive offices)

                                  LISA C. BERRY
                       VICE PRESIDENT AND GENERAL COUNSEL
                             KLA-TENCOR CORPORATION
                                 160 RIO ROBLES
                           SAN JOSE, CALIFORNIA 95134
                                 (408) 875-3000
 (Name, address, including zip code, and telephone number, including area code,
                             of agent for service)

                                   Copies to:
                                LARRY W. SONSINI
                                JUDITH M. O'BRIEN
                                BRET M. DiMARCO
                        WILSON SONSINI GOODRICH & ROSATI
                            PROFESSIONAL CORPORATION
                               650 PAGE MILL ROAD
                           PALO ALTO, CALIFORNIA 94304
                                 (650) 493-9300

        Approximate date of commencement of proposed sale to the public:
   FROM TIME TO TIME AFTER THE EFFECTIVE DATE OF THIS REGISTRATION STATEMENT.


        If the only securities being registered on this Form are to be offered
pursuant to dividend or interest reinvestment plans, please check the following
box. [ ]


        If any of the securities being registered on this Form are to be offered
on a delayed or continuous basis pursuant to Rule 415 under the Securities Act
of 1933, other than securities offered only in connection with dividend or
interest reinvestment plans, check the following box. [X]


        If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering. [ ]


        If this Form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. [ ]


        If delivery of the prospectus is expected to be made pursuant to Rule
434, please check the following box. [ ]

                         CALCULATION OF REGISTRATION FEE
<TABLE>
<CAPTION>
=======================================================================================================================
                                                             PROPOSED MAXIMUM      PROPOSED MAXIMUM
     TITLE OF EACH CLASS OF                 AMOUNT TO BE    OFFERING PRICE PER    AGGREGATE OFFERING        AMOUNT OF
   SECURITIES TO BE REGISTERED               REGISTERED          SHARE(1)             PRICE(1)         REGISTRATION FEE
- -----------------------------------------------------------------------------------------------------------------------
<S>                                         <C>             <C>                   <C>                  <C>    
Common Stock, par value $0.001 per share     1,800,000           $40.25            $72,450,000             $21,955
=======================================================================================================================
</TABLE>

(1) Estimated solely for the purpose of computing the registration fee required
    by Section 6(b) of the Securities Act and computed pursuant to Rule 457(c)
    under the Securities Act based upon the average of the high and low prices
    of the Common Stock on May 7, 1998 as reported on the Nasdaq National
    Market.

        The registrant hereby amends this Registration Statement on such date or
dates as may be necessary to delay its effective date until the registrant shall
file a further amendment which specifically states that this Registration
Statement shall thereafter become effective in accordance with Section 8(a) of
the Securities Act of 1933 or until the Registration Statement shall become
effective on such date as the Commission, acting pursuant to said Section 8(a),
may determine.


================================================================================

<PAGE>   2


INFORMATION CONTAINED HEREIN IS SUBJECT TO COMPLETION OR AMENDMENT. A
REGISTRATION STATEMENT RELATING TO THESE SECURITIES HAS BEEN FILED WITH THE
SECURITIES AND EXCHANGE COMMISSION. THESE SECURITIES MAY NOT BE SOLD NOR MAY
OFFERS TO BUY BE ACCEPTED PRIOR TO THE TIME THE REGISTRATION STATEMENT BECOMES
EFFECTIVE. THIS PROSPECTUS SHALL NOT CONSTITUTE AN OFFER TO SELL OR THE
SOLICITATION OF AN OFFER TO BUY NOR SHALL THERE BE ANY SALE OF THESE SECURITIES
IN ANY STATE IN WHICH SUCH OFFER, SOLICITATION OR SALE WOULD BE UNLAWFUL PRIOR
TO REGISTRATION OR QUALIFICATION UNDER THE SECURITIES LAWS OF ANY SUCH STATE.


PROSPECTUS (Subject to Completion)
Issued May 12, 1998

                                1,800,000 SHARES

                             KLA-TENCOR CORPORATION
                                  COMMON STOCK

                             ----------------------

     This Prospectus relates to the public offering, which is not being
underwritten, of up to 1,800,000 shares of Common Stock, par value $0.001 per
share (the "Shares"), of KLA-Tencor Corporation ("KLA-Tencor" or the "Company"),
which may be offered from time to time by certain stockholders of the Company or
by pledgees, donees, transferees or other successors in interest that receive
such shares as a gift, partnership distribution or other non-sale related
transfer (the "Selling Stockholders"). The Company will receive no part of the
proceeds of such sales. All of the Shares were originally issued by the Company
in connection with the Company's acquisition of AMRay, Inc., a Delaware
corporation ("AMRay"), by and through a merger of Alpine Acquisition, Inc., a
wholly-owned subsidiary of KLA-Tencor ("Alpine"), with and into AMRay (the
"Acquisition"). The Shares were issued pursuant to an exemption from the
registration requirements of the Securities Act of 1933, as amended (the
"Securities Act"), provided by Rule 506 of Regulation D thereunder. The Shares
are being registered by the Company pursuant to a certain agreement among the
Selling Stockholders and the Company.

     The Shares may be offered by the Selling Stockholders from time to time in
one or more transactions as described under "Plan of Distribution." To the
extent required, the number of shares to be sold, the name of the Selling
Stockholder(s), the purchase price, the name of any agent or broker-dealer, and
any applicable commissions, discounts or other items constituting compensation
to such agent or broker-dealer with respect to a particular offering will be set
forth in a supplement or supplements to this Prospectus (each, a "Prospectus
Supplement"). The aggregate proceeds to the Selling Stockholder(s) from the sale
of the shares offered from time to time hereby will be the purchase price of the
Shares sold less commissions, discounts and other compensation, if any, paid by
the Selling Stockholder(s) to any agent or broker-dealer. The price at which any
of the Shares may be sold, and the commissions, if any paid in connection with
any such sale, are unknown and may vary from transaction to transaction. The
Company will pay all expenses incident to the offering and sale of the Shares to
the public other than any commissions, discounts and other compensation of
underwriters, dealers or agents and any transfer taxes. See "Selling
Stockholders" and "Plan of Distribution."

     The Company's Common Stock is listed on the Nasdaq National Market under
the symbol "KLAC." On May 8, 1998, the last sale price of the Company's Common
Stock was $41.625 per share.

                                   ----------

 THIS OFFERING INVOLVES A HIGH DEGREE OF RISK. SEE "RISK FACTORS" COMMENCING ON
                                 PAGE 4 HEREOF.

                                   ----------

     The Securities and Exchange Commission may take the view that, under
certain circumstances, the Selling Stockholders and any broker-dealers or agents
that participate with the Selling Stockholders in the distribution of the Shares
may be deemed to be "underwriters" within the meaning of the Securities Act.
Commissions, discounts or concessions received by any such broker-dealer or
agent may be deemed to be underwriting commissions under the Securities Act. The
Company and the Selling Stockholders have agreed to certain indemnification
arrangements. See "Plan of Distribution."

                                   ----------

    THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES
       AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS
         THE SECURITIES AND EXCHANGE COMMISSION OR ANY STATE SECURITIES
               COMMISSION PASSED UPON THE ACCURACY OR ADEQUACY OF
                   THIS PROSPECTUS. ANY REPRESENTATION TO THE
                         CONTRARY IS A CRIMINAL OFFENSE.

                                   ----------

                   THE DATE OF THIS PROSPECTUS IS MAY 12, 1998


<PAGE>   3

                              AVAILABLE INFORMATION

        The Company is subject to the informational requirements of the
Securities Exchange Act of 1934, as amended (the "Exchange Act"), and in
accordance therewith files reports, proxy and information statements and other
information with the Securities and Exchange Commission (the "Commission"). Such
reports, proxy and information statements and other information filed by the
Company can be inspected and copied at the public reference facilities
maintained by the Commission at Room 1024, Judiciary Plaza, 450 Fifth Street,
N.W., Washington, D.C. 20549, and at the following Regional Offices of the
Commission: Northeast Regional Office, Seven World Trade Center, Suite 1300, New
York, New York 10048 and Midwest Regional Office, Northwest Atrium Center, 500
West Madison Street, Suite 1400, Chicago, Illinois 60661. Copies of such
material can be obtained from the Public Reference Section of the Commission at
Judiciary Plaza, 450 Fifth Street, N.W., Washington, D.C. 20549 at prescribed
rates. The Commission maintains a web site that contains reports, proxy and
information statements and other information regarding registrants that file
electronically with the Commission. The address of the Commission's web site is
http://www.sec.gov. The Common Stock of the Company is listed on the Nasdaq
National Market, and such reports, proxy and information statements and other
information concerning the Company may be inspected at the offices of Nasdaq
Operations, 1735 K Street, N.W., Washington, D.C. 20006-1506.

        This Prospectus constitutes a part of a Registration Statement on Form
S-3 (herein, together with all amendments and exhibits, referred to as the
"Registration Statement") filed by the Company with the Commission under the
Securities Act. This Prospectus does not contain all of the information set
forth in the Registration Statement, certain parts of which are omitted in
accordance with the rules and regulations of the Commission. For further
information with respect to the Company and the Shares offered hereby, reference
is hereby made to the Registration Statement. The Registration Statement may be
inspected at the public reference facilities maintained by the Commission at the
addresses set forth in the preceding paragraph. The Company has filed the
Registration Statement electronically with the Commission via the Commission's
Electronic Data Gathering, Analysis, and Retrieval (EDGAR) system. Statements
contained herein concerning any document filed as an exhibit are not necessarily
complete and, in each instance, reference is made to the copy of such document
filed as an exhibit to the Registration Statement. Each such statement is
qualified in its entirety by such reference. The Company intends to distribute
to its stockholders annual reports containing audited financial statements and
will make available copies of quarterly reports for the first three quarters of
each fiscal year containing unaudited interim financial information.


                 INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

        The following documents filed with the Commission are hereby
incorporated by reference in this Prospectus:

        (1)    The Company's Annual Report on Form 10-K for the fiscal year
               ended June 30, 1997 (File No. 000-09992);

        (2)    The Company's Quarterly Reports on Form 10-Q for the quarters
               ended March 31, 1998, December 31, 1997 and September 30, 1997
               (File No. 000-09992);

        (3)    All other documents filed by the Company pursuant to Section
               13(a) or 15(d) of the Exchange Act since the end of the fiscal
               year covered by the annual report referred to in (1) above; and

        (4)    The description of the Registrant's Common Stock as set forth in
               the Registration Statement filed by the Registrant on Form 8-A on
               March 29, 1989 (File No. 000-09992) pursuant to Section 12(g) of
               the Exchange Act and any amendments or reports thereto filed with
               the Securities and Exchange Commission for the purpose of
               updating such



                                       -2-

<PAGE>   4

               description including Amendment No. 1 to Form 8-A filed September
               25, 1995 and Amendment No. 2 to Form 8-A filed September 24,
               1996.

        All reports and other documents subsequently filed by the Company
pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act after the date
of this Prospectus and prior to the termination of this offering shall be deemed
to be incorporated by reference into this Prospectus, to the extent required,
and to be a part of this Prospectus from the date of filing of such reports and
documents.

        Any statement contained in a document incorporated by reference into
this Prospectus shall be deemed to be modified or superseded for purposes of
this Prospectus to the extent that a statement contained herein or in any other
subsequently filed document that also is or is deemed to be incorporated by
reference herein modifies or supersedes such statement. Any statement so
modified or superseded shall not be deemed, except as so modified or superseded,
to constitute a part of this Prospectus.

        The Company hereby undertakes to provide without charge to each person,
including any beneficial owner, to whom a copy of this Prospectus is delivered,
upon written or oral request of such person, a copy of any or all of the
information that has been incorporated by reference in this Prospectus (other
than exhibits to such documents, unless such exhibits are specifically
incorporated by reference into the information that this Prospectus
incorporates). Requests for such documents should be submitted in writing to
Investor Relations, KLA-Tencor Corporation, 160 Rio Robles, San Jose, California
95134 or by telephone at (408) 875-3000.


                                   THE COMPANY

        KLA-Tencor Corporation ("KLA-Tencor" or the "Company") is a leader in
the design, manufacture, marketing and service of yield management and process
monitoring systems for the semiconductor industry. The Company uses its
technical expertise and understanding of customer needs to supply unique yield
management solutions. In addition, the Company has one of the broadest lines of
wafer inspection, thin film measurement, metrology and reticle inspection
systems available in the semiconductor industry. The Company's systems are used
to analyze product and process quality at critical steps in the manufacturing
process for integrated circuits and to provide feedback to the Company's
customers in order that fabrication problems can be identified, addressed and
contained. This understanding of defect sources and how to contain them enables
semiconductor manufacturers to increase yields. Increasing yields is important
because semiconductor fabrication facilities are increasingly expensive to build
and equip. Yield management and process monitoring systems, which typically
represent a small percentage of the total investment required to build and equip
a fabrication facility, enable integrated circuit manufacturers to leverage
these expensive facilities and improve their returns on investment. Marketing
and selling its products worldwide to virtually all of the major semiconductor
manufacturers, the Company derives revenues primarily from product sales,
principally through its direct sales force and, to a lesser extent, through
distributors.

        The Company was incorporated in Delaware in July 1975. Its headquarters
is located at 160 Rio Robles, San Jose, California, 95134, telephone (408)
875-3000.



                                       -3-

<PAGE>   5



                           FORWARD-LOOKING STATEMENTS

        This Prospectus includes or incorporates by reference forward-looking
statements that involve risks and uncertainties. The statements contained or
incorporated by reference in this Prospectus that are not purely historical are
forward-looking statements within the meaning of Section 27A of the Securities
Act and Section 21E of the Exchange Act. Words such as "anticipates," "expects,"
"intends," "plans," "believes," "seeks," "estimates" and variations of such
words and similar expressions are intended to identify such forward-looking
statements. These statements are not guarantees of future performance and are
subject to certain risks, uncertainties and assumptions that are difficult to
predict; therefore, actual results may differ materially from those expressed or
forecasted in any such forward-looking statements. Such forward-looking
statements are based on current expectations, estimates and projections about
the Company's industry, management's beliefs, and assumptions made by
management.


                                  RISK FACTORS

        The Shares offered hereby are speculative in nature and involve a high
degree of risk. In addition to risk factors contained herein, the risk factors
and other information contained in the Company's Annual Report on Form 10-K for
the fiscal year ended June 30, 1997 are incorporated by reference herein. See
"Incorporation of Certain Documents by Reference." More specifically, risk
factors can be found referenced in the Company's Annual Report on Form 10-K for
the fiscal year ended June 30, 1997 under "Management's Discussion and Analysis
of Financial Condition and Results of Operations--Other Factors Affecting
Company Results. Such risk factors and other information should be considered
carefully before purchasing the offered Shares. Unless required by law, the
Company undertakes no obligation to update publicly any forward-looking
statements, whether as a result of new information, future events or otherwise.
Investors should carefully review the risk factors and other information set
forth in the reports and other documents the Company files from time to time
with the Commission.

        The Company's quarterly operating results have fluctuated in the past
and may fluctuate in the future. During the last three months results have been
adversely affected as the Company experienced declines in revenues and margins
during this period due to the semiconductor industry's reaction to the Asian
financial crisis, low DRAM pricing and DRAM overcapacity. The Company's
operating results are dependent on many factors, including the economic
conditions in the semiconductor and related industries, both in the US and
abroad, the size and timing of the receipt of orders from customers, customer
cancellations or delays of shipments, the Company's ability to develop,
introduce, and market new and enhanced products on a timely basis, among others.
The Company has experienced reductions in orders, cancellations and delays in
shipments which may continue to adversely affect sales and margins in future
periods. The Company expects unfavorable effects on orders, sales and margins to
persist at least through the remainder of the fiscal year and possibly beyond.
The Company's expense levels are based, in part, on expectations of future
revenues. If revenue levels in a particular period do not meet expectations of
increased revenues, operating results will be adversely affected.

        The Company's business depends and will continue to depend in the future
upon the capital equipment expenditures of semiconductor manufacturers, which in
turn depend on the current and anticipated market demand for integrated circuits
and products utilizing integrated circuits. The current industry downturn has
had an adverse effect on the semiconductor industry's level of capital
expenditures. The Company believes that it is relatively well positioned for
this downturn because of its array of products, its focus on yield improvement
and process development rather than pure capacity, its sales of metrology
products to non-semiconductor industries and its strong balance sheet.



                                      -4-

<PAGE>   6

Nevertheless, there can be no assurance that the Company's current position will
be able to withstand the effects of a industry downturn.

        Rapid technological changes in semiconductor manufacturing processes
subject the semiconductor manufacturing equipment industry to increased pressure
to maintain technological parity with deep submicron process technology. While
focused on controlling expenses to address the downturn in the semiconductor
industry, the Company continues to believe that its future success will depend
in part upon its ability to develop, manufacture and successfully introduce new
products with improved capabilities including those for 300mm wafers and devices
with critical dimensions at .25-micron and below and to continue to enhance
existing products. Due to the risks inherent in transitioning to new products,
the Company will be required to forecast demand for new products while managing
the transition from older products. There can be no assurance that the Company
will successfully and timely develop and manufacture new hardware and software
products or that new hardware and software products introduced by the Company
will be accepted in the marketplace. If new products have reliability or quality
problems then reduced orders, higher manufacturing costs, delays in collecting
accounts receivable and additional service and warranty expense may result.
Additionally, there can be no assurance that future technologies, processes or
product developments will not render the Company's current product offerings
obsolete. However, if the Company does not continue to successfully introduce
new products, its results of operations will be adversely affected. The Company
expects to continue to make significant investments in research and development
and to sustain its current spending levels for customer support in fiscal year
1998 to meet current customer requirements and effectively position the Company
for growth when the business cycle turns favorable.

        The semiconductor equipment industry is highly competitive. The Company
has experienced and expects to continue to face substantial competition
throughout the world. The Company believes that to remain competitive, it will
require significant financial resources in order to offer a broad range of
products, to maintain customer service and support centers worldwide, and to
invest in product and process research and development. The Company believes
that the semiconductor equipment industry is becoming increasingly dominated by
large manufacturers, who have the resources to support customers on a worldwide
basis. Many of these competitors have substantially greater financial resources
and more extensive engineering, manufacturing, marketing and customer service
and support capabilities than the Company. In addition, there are smaller
emerging semiconductor equipment companies which provide innovative technology.
No assurance can be given that the Company will be able to compete successfully
worldwide.

         The Company expects that international revenues will continue to
represent a significant percentage of its net revenues. International revenues
and operations may be adversely affected by imposition of governmental controls,
restrictions on export technology, political instability, trade restrictions,
changes in tariffs and the difficulties associated with staffing and managing
international operations. In addition, international sales may be adversely
affected by economic conditions in each country. The future performance of the
Company will be dependent, in part, upon its ability to continue to compete
successfully in Asia, one of the largest areas for the sale of yield management
and process monitoring equipment. Countries in the Asia Pacific region,
including Japan, Korea and Taiwan, have experienced weaknesses in their
currency, banking and equity markets in recent periods. These weaknesses may
continue to adversely affect demand for the Company's products, the U.S. dollar
value of the Company's foreign currency denominated sales, the availability and
supply of resources, and the Company's consolidated results of operations.
Although the Company attempts to manage near term currency risks through
"hedging," there can be no assurance that such efforts will be adequate. These
factors may have a material adverse effect on the Company's future business and
financial results.



                                      -5-

<PAGE>   7


                                      SELECTED FINANCIAL DATA

                                  Five Year Financial Highlights
                               (in thousands, except per share data)


<TABLE>
<CAPTION>
                                                                                                                      THREE MONTHS
                                                                                                                          ENDED
                                                               YEAR ENDED JUNE 30,                                      MARCH 31,
                                 -----------------------------------------------------------------------------         ----------
                                    1993            1994            1995               1996            1997               1998
                                 ----------      ----------      ----------         ----------      ----------         ----------
<S>                              <C>             <C>             <C>                <C>             <C>               <C>       
Revenues ....................    $  261,105      $  376,454      $  695,950         $1,094,492      $1,031,824         $  274,164
Net income ..................    $   11,507      $   40,443      $  104,811(1)      $  196,634      $  105,396(2)      $   28,971(3)
Net income per share(4)
   Basic ....................    $     0.22      $     0.61      $     1.40(1)      $     2.42      $     1.29(2)      $     0.34(3)
   Diluted ..................    $     0.19      $     0.59      $     1.34(1)      $     2.34      $     1.24(2)      $     0.33(3)
Shares used in per share
   calculation(4)
   Basic ....................        51,968          66,316          74,758             81,148          81,943             84,985
   Diluted ..................        60,841          69,076          78,427             84,195          85,203             87,785
</TABLE>



<TABLE>
<CAPTION>
                                                                                                                       AS OF   
                                                                 AS OF JUNE 30,                                       MARCH 31,
                                     --------------------------------------------------------------------------      ----------
                                        1993            1994            1995            1996            1997            1998
                                     ----------      ----------      ----------      ----------      ----------      ----------
<S>                                  <C>             <C>             <C>             <C>             <C>           <C>       
Cash, cash equivalents and
   marketable securities ......      $   70,044      $  174,305      $  385,040      $  468,475      $  687,249      $  714,567
Working capital ...............      $  133,084      $  277,791      $  452,350      $  591,397      $  535,256      $  551,723
Total assets ..................      $  260,485      $  430,453      $  850,406      $1,157,919      $1,343,307      $1,504,839
Stockholders' equity ..........      $  165,379      $  307,334      $  652,222      $  870,999      $1,014,613      $1,174,634
</TABLE>

- ----------

(1)     Includes a net charge of $16.2 million for write-off of acquired
        in-process technology. Net income, basic and diluted net income per
        share would have been $121 million, $1.62 and $1.54, respectively,
        excluding this charge.

(2)     Includes merger, restructuring and other costs of $60.6 million. Net
        income, basic and diluted net income per share would have been $151.3
        million, $1.85 and $1.78, respectively, excluding these costs.

(3)     Includes non-recurring acquisition and restructuring charges of $3.1
        million. Net income, basic and diluted net income per share would have
        been $31.1 million, $0.37 and $0.35, respectively, excluding these
        costs.

(4)     The Company adopted Statement of Accounting Standards No. 128 ("FAS
        128") "Earnings Per Share." FAS 128 requires presentation of both basic
        and diluted net income per share on the income statement for all periods
        presented. Basic net income per share is computed by dividing net income
        available to common stockholders by the weighted average number of
        common shares outstanding during the period. In computing diluted net
        income per share, the average stock price for the period is used in
        determining the number of shares assumed to be purchased from the
        exercise of stock options. Diluted net income per share is computed
        using the weighted average number of common and potential common stock
        equivalent shares outstanding during the period.

                                 USE OF PROCEEDS

        The Company will not receive any of the proceeds from the sale of the
Shares. All proceeds from the sale of the Shares will be for the account of the
Selling Stockholders, as described below. See "Selling Stockholders" and "Plan
of Distribution."


                              SELLING STOCKHOLDERS

        The following table sets forth, as of the date of this Prospectus, the
name of each of the Selling Stockholders, the number of Shares that each such
Selling Stockholder owns as of such date, the number of Shares owned by each
Selling Stockholder that may be offered for sale from time to time by this
Prospectus, and the number of Shares to be held by each such Selling Stockholder
assuming the sale of all of the Shares offered hereby. Except as indicated, none
of the Selling Stockholders has held any position or office or had a material
relationship with the Company or any of its predecessors or affiliates within
the past three years other than as a result of the ownership of the Company's
Common 



                                      -6-

<PAGE>   8
Stock. The Company may amend or supplement this Prospectus from time to time to
update the disclosure set forth herein.


<TABLE>
<CAPTION>
                                                         SHARES WHICH     SHARES BENEFICIALLY OWNED
                                          SHARES          MAY BE SOLD         AFTER OFFERING(4)
                                       BENEFICIALLY       PURSUANT TO      ---------------------
        SELLING STOCKHOLDER(1)            OWNED(2)     THIS PROSPECTUS(3)   NUMBER        PERCENT
- ------------------------------------   ------------   ------------------   ------        -------
<S>                                    <C>            <C>                 <C>            <C>
Gerald T. Cameron, Sr.                    80,547            80,547            0              0
Alice J. Cameron                          80,547            80,547            0              0

Gerald T. Cameron, Jr.                   249,100           249,100            0              0
Cynthia W. Cameron                         8,017             8,017            0              0
Gerald T. Cameron, Jr.
  as Cust. For Meredith L. Cameron         8,017             8,017            0              0
Gerald T. Cameron, Jr.
  as Cust. For Caroline L. Cameron         8,017             8,017            0              0

Brian L. Cameron                         249,100           249,100            0              0
Doris R. Cameron                           8,017             8,017            0              0
Brian L. Cameron
  as Cust. For Stephen M. Cameron          8,017             8,017            0              0
Brian L. Cameron
  as Cust. For Christine N. Cameron        8,017             8,017            0              0

Gregory R. Cameron                       233,066           233,066            0              0
Sharon M. Cameron                          8,017             8,017            0              0
Gregory R. Cameron
  as Cust. For Courtney S. Cameron         8,017             8,017            0              0
Gregory R. Cameron
  as Cust. For Kristen M. Cameron          8,017             8,017            0              0
Gregory R. Cameron
  as Cust. For Jennifer A. Cameron         8,017             8,017            0              0
Gregory R. Cameron
  as Cust. For Melissa J. Cameron          8,017             8,017            0              0

Janice C. Coady                          241,083           241,083            0              0
Edward P. Coady                            8,017             8,017            0              0
Janice C. Coady
  as Cust. For Cameron P. Coady            8,017             8,017            0              0
Janice C. Coady
  as Cust. For Christopher J. Coady        8,017             8,017            0              0
Janice C. Coady
  as Cust. For Connor E. Coady             8,017             8,017            0              0

Regina C. Fuertes                        257,117           257,117            0              0
Felix R. Fuertes                           8,017             8,017            0              0
Regina C. Fuertes
  as Cust. For Francesca I. Fuertes        8,017             8,017            0              0

Paula M. Swain                           241,083           241,083            0              0
Bernard L. Swain                           8,017             8,017            0              0
Paula M. Swain
  as Cust. For Timothy D. Swain            8,017             8,017            0              0
Paula M. Swain
  as Cust. For Michael P. Swain            8,017             8,017            0              0
Paula M. Swain
  as Cust. For Kelley P. Swain             8,017             8,017            0              0
                                       ---------         ---------           ---            ---

TOTAL                                  1,800,000         1,800,000            0              0
</TABLE>

- ----------

(1)     Each Selling Stockholder is subject to an affiliate agreement whereby
        such Stockholder may not transfer, dispose of or enter into any other
        transaction (through derivatives or otherwise) intended to reduce or
        having the effect of reducing, directly or indirectly, such
        stockholder's risk relative to, any shares of the Common Stock until
        such time as financial results covering at least 30 days of the combined
        operations of KLA-Tencor and AMRay have been published by KLA-Tencor in
        an Annual Report on Form 10-K, a Quarterly Report on Form 10-Q, a
        Current Report on Form 8-K, a quarterly earnings report, a press release
        or other public issuance that includes combined sales and net income of
        AMRay and KLA-Tencor. KLA-Tencor does not expect to publish such
        combined financial information prior to the filing of the Annual Report
        on Form 10-K for the fiscal year ending June 30, 1998, which is required
        to be filed on or before September 28, 1998.

(2)     The number and percentage of shares beneficially owned is determined in
        accordance with Rule 13d-3 of the Exchange Act, and the information is
        not necessarily indicative of beneficial ownership for any other
        purpose. Under such rule, beneficial ownership includes any shares as to
        which the individual has sole or shared voting power or investment power
        and also any shares which the individual has the right to acquire within
        60 days of the date of this Prospectus through the exercise of any stock
        option or other right. Unless otherwise indicated in the footnotes, each
        person has sole voting and investment power (or shares such powers with
        his or her spouse) with respect to the shares shown as beneficially
        owned.

(3)     The number and percentage of shares beneficially owned includes an
        aggregate of 105,000 shares of Common Stock beneficially owned by the
        Selling Stockholders that have been deposited into escrow pursuant to
        that certain Agreement and Plan of Reorganization dated March 16, 1998
        to secure the respective indemnification obligations of the Selling
        Stockholders thereunder (the "Escrowed Shares"). To the extent that no
        claims have been made against the escrow, the Escrowed Shares will be
        released from escrow as follows: 75,000 Escrowed Shares shall be
        released no later than April 8, 1999, and the remaining 30,000 Escrowed
        Shares no later than April 8, 2001. In addition, it is anticipated that
        up to 30,000 Escrowed Shares may be sold prior to the termination of the
        escrow period, with the proceeds deposited into escrow for the
        applicable period. 

(4)     Assumes the sale of all Shares offered hereby, including the Escrowed
        Shares, if any.


                              PLAN OF DISTRIBUTION

        The Shares covered by this Prospectus may be offered and sold from time
to time by the Selling Stockholders. The Selling Stockholders will act
independently of the Company in making decisions with respect to the timing,
manner and size of each sale. The Selling Stockholders may sell the Shares being
offered hereby on the Nasdaq National Market, or otherwise, at prices and under
terms then prevailing or at prices related to the then current market price or
at negotiated prices. The Shares may be sold by one or more of the following
means of distribution: (a) a block trade in which the broker-dealer so engaged
will attempt to sell Shares as agent, but may position and resell a portion of
the block as principal to facilitate the transaction; (b) purchases by a
broker-dealer as principal and resale by such broker-dealer for its own account
pursuant to this Prospectus; (c) an over-the-counter distribution in accordance
with the rules of the Nasdaq National Market; (d) ordinary brokerage
transactions and transactions in which the broker solicits purchasers; and (e)
in privately negotiated transactions. To the extent required, this Prospectus
may be amended and supplemented from time to time to describe a specific plan of
distribution. In connection with distributions of the Shares or otherwise, the
Selling Stockholders may enter into hedging transactions with broker-dealers or
other financial institutions. In connection with such transactions,
broker-dealers or other financial institutions may engage in short sales of the
Company's Common Stock in the course of hedging the positions they assume with
Selling Stockholders. The Selling Stockholders may also sell the Company's
Common Stock short and redeliver the Shares to close out such short positions.
The Selling Stockholders may also enter into option or other transactions with
broker-dealers or other financial institutions which require the delivery to
such 



                                      -7-

<PAGE>   9

broker-dealer or other financial institution of Shares offered hereby, which
Shares such broker-dealer or other financial institution may resell pursuant to
this Prospectus (as supplemented or amended to reflect such transaction). The
Selling Stockholders may also pledge Shares to a broker-dealer or other
financial institution, and, upon a default, such broker-dealer or other
financial institution, may effect sales of the pledged Shares pursuant to this
Prospectus (as supplemented or amended to reflect such transaction). In
addition, any Shares that qualify for sale pursuant to Rule 144 may be sold
under Rule 144 rather than pursuant to this Prospectus.

        In effecting sales, brokers, dealers or agents engaged by the Selling
Stockholders may arrange for other brokers or dealers to participate. Brokers,
dealers or agents may receive commissions, discounts or concessions from the
Selling Stockholders in amounts to be negotiated prior to the sale. Such brokers
or dealers and any other participating brokers or dealers may be deemed to be
"underwriters" within the meaning of the Securities Act in connection with such
sales, and any such commissions, discounts or concessions may be deemed to be
underwriting discounts or commissions under the Securities Act. The Company will
pay all expenses incident to the offering and sale of the Shares to the public
other than any commissions and discounts of underwriters, dealers or agents and
any transfer taxes.

        In order to comply with the securities laws of certain states, if
applicable, the Shares must be sold in such jurisdictions only through
registered or licensed brokers or dealers. In addition, in certain states the
Shares may not be sold unless they have been registered or qualified for sale in
the applicable state or an exemption from the registration or qualification
requirement is available and is complied with.

        The Company has advised the Selling Stockholders that the
anti-manipulation rules of Regulation M under the Exchange Act may apply to
sales of Shares in the market and to the activities of the Selling Stockholders
and their affiliates. In addition, the Company will make copies of this
Prospectus available to the Selling Stockholders and has informed them of the
need for delivery of copies of this Prospectus to purchasers at or prior to the
time of any sale of the Shares offered hereby. The Selling Stockholders may
indemnify any broker-dealer that participates in transactions involving the sale
of the Shares against certain liabilities, including liabilities arising under
the Securities Act.

        At the time a particular offer of Shares is made, if required, a
Prospectus Supplement will be distributed that will set forth the number of
Shares being offered and the terms of the offering, including the name of any
underwriter, dealer or agent, the purchase price paid by any underwriter, any
discount, commission and other item constituting compensation, any discount,
commission or concession allowed or reallowed or paid to any dealer, and the
proposed selling price to the public.

        The sale of Shares is subject to compliance by the Selling Stockholders
with certain contractual restrictions with the Company. There can be no
assurance that the Selling Stockholders will sell all or any of the Shares.

        The Company has agreed with the Selling Stockholders to use commercially
reasonable efforts to keep the Registration Statement of which this Prospectus
constitutes a part effective for up to twelve months following the effectiveness
of such Registration Statement. The Company intends to remove from registration
any of the Shares not sold by the Selling Stockholders at the end of such twelve
month period; however, it is anticipated that at such time any unsold shares may
be freely tradable subject to compliance with Rule 144 of the Securities Act.



                                      -8-

<PAGE>   10

                                  LEGAL MATTERS

        The validity of the Shares offered hereby will be passed upon by Wilson
Sonsini Goodrich & Rosati, Professional Corporation, Palo Alto, California,
counsel to the Company.


                                     EXPERTS

        The consolidated financial statements in this Prospectus incorporated by
reference to the Company's Annual Report on Form 10-K for the year ended June
30, 1997, have been so incorporated in reliance on the report of Price
Waterhouse LLP, independent accountants, given on the authority of said firm as
experts in auditing and accounting.



                                       -9-

<PAGE>   11


================================================================================


        NO PERSON IS AUTHORIZED IN CONNECTION WITH ANY OFFERING MADE BY THIS
PROSPECTUS TO GIVE ANY INFORMATION OR TO MAKE ANY REPRESENTATIONS NOT CONTAINED
IN THIS PROSPECTUS, AND, IF GIVEN OR MADE, SUCH INFORMATION OR REPRESENTATIONS
MUST NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED BY THE COMPANY, ANY SELLING
STOCKHOLDER OR BY ANY OTHER PERSON. THIS PROSPECTUS DOES NOT CONSTITUTE AN OFFER
TO SELL OR A SOLICITATION OF AN OFFER TO BUY ANY SECURITY OTHER THAN THE SHARES
OFFERED HEREBY, NOR DOES IT CONSTITUTE AN OFFER TO SELL OR A SOLICITATION OF AN
OFFER TO BUY ANY OF THE SHARES OFFERED HEREBY TO ANY PERSON IN ANY JURISDICTION
IN WHICH IT IS UNLAWFUL TO MAKE SUCH AN OFFER OR SOLICITATION. NEITHER THE
DELIVERY OF THIS PROSPECTUS NOR ANY SALE OF OR OFFER TO SELL THE SHARES MADE
HEREUNDER SHALL UNDER ANY CIRCUMSTANCES CREATE ANY IMPLICATION THAT THERE HAS
BEEN NO CHANGE IN THE AFFAIRS OF THE COMPANY SINCE THE DATE HEREOF OR THAT THE
INFORMATION CONTAINED HEREIN IS CORRECT AS OF ANY TIME SUBSEQUENT TO THE DATE
HEREOF.


                                TABLE OF CONTENTS


<TABLE>
<CAPTION>
                                                                             Page
                                                                             ----
<S>                                                                          <C>
Available Information ...................................................      2
Incorporation of Certain Documents By Reference .........................      2
The Company .............................................................      3
Forward-Looking Statements ..............................................      4
Risk Factors ............................................................      4
Selected Financial Data .................................................      6
Use of Proceeds .........................................................      6
Selling Stockholders ....................................................      6
Plan of Distribution ....................................................      7
Legal Matters ...........................................................      9
Experts .................................................................      9
</TABLE>
================================================================================



================================================================================

                             KLA-TENCOR CORPORATION



                                1,800,000 SHARES

                                       OF

                                  COMMON STOCK


                                   ----------
                                   PROSPECTUS
                                   ----------


                                  May 12, 1998



================================================================================


<PAGE>   12

                                     PART II

                   INFORMATION NOT REQUIRED IN THE PROSPECTUS


ITEM 14.       OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION.

               The Company will pay all expenses incident to the offering and
sale to the public of the shares being registered other than any commissions and
discounts of underwriters, dealers or agents and any transfer taxes. Such
expenses are set forth in the following table. All of the amounts shown are
estimates except the Securities and Exchange Commission ("SEC") registration fee
and the Nasdaq National Market listing fee.

<TABLE>
<S>                                                              <C>    
        SEC registration fee ..........................          $21,955
        NASDAQ National Market listing fee ............           17,500
        Legal fees and expenses .......................           10,000
        Accounting fees and expenses ..................           10,000
        Miscellaneous expenses ........................           20,000
                                                                 -------
               Total ..................................          $79,455
</TABLE>


ITEM 15.       INDEMNIFICATION OF DIRECTORS AND OFFICERS.

               Section 145(a) of the Delaware General Corporation Law (the
"DGCL") provides in relevant part that "[a] corporation may indemnify any person
who was or is a party or is threatened to be made a party to any threatened,
pending or completed action, suit or proceeding, whether civil, criminal,
administrative or investigative (other than an action by or in the right of the
corporation) by reason of the fact that he is or was a director, officer,
employee or agent of the corporation, or is or was serving at the request of the
corporation as a director, officer, employee or agent of another corporation,
partnership, joint venture, trust or other enterprise, against expenses
(including attorneys' fees), judgments, fines and amounts paid in settlement
actually and reasonably incurred by him in connection with such action, suit or
proceeding if he acted in good faith and in a manner he reasonably believed to
be in or not opposed to the best interests of the corporation, and, with respect
to any criminal action or proceeding, had no reasonable cause to believe his
conduct was unlawful." With respect to derivative actions, Section 145(b) of the
DGCL provides in relevant part that "[a] corporation may indemnify any person
who was or is a party or is threatened to be made a party to any threatened,
pending or completed action or suit by or in the right of the corporation to
procure a judgment in its favor. . . [by reason of his service in one of the
capacities specified in the preceding sentence] against expenses (including
attorneys' fees) actually and reasonably incurred by him in connection with the
defense or settlement of such action or suit if he acted in good faith and in a
manner he reasonably believed to be in or not opposed to the best interests of
the corporation and except that no indemnification shall be made in respect of
any claim, issue or matter as to which such person shall have been adjudged to
be liable to the corporation unless and only to the extent that the Court of
Chancery or the court in which such action or suit was brought shall determine
upon application that, despite the adjudication of liability but in view of all
the circumstances of the case, such person is fairly and reasonably entitled to
indemnity for such expenses which the Court of Chancery or such other court
shall deem proper."

               The Company's Amended and Restated Certificate of Incorporation
provides that, to the fullest extent permitted by the DGCL, no director of the
Company shall be personally liable to the Company or its stockholders for
monetary damages for breach of fiduciary duty as a director. The Amended and
Restated Certificate of Incorporation also provides that no amendment or repeal
of such 



                                      II-1

<PAGE>   13

provision shall apply to or have any effect on the right to indemnification
permitted thereunder with respect to claims arising from acts or omissions
occurring in whole or in part before the effective date of such amendment or
repeal whether asserted before or after such amendment or repeal.

               The Company's Bylaws provide that the Company shall indemnify to
the full extent permitted by the DGCL each of its directors, officers, employees
and other agents against expenses actually and reasonably incurred in connection
with any proceeding arising by reason of the fact that such person is or was an
agent of the Company.

               The Company has entered into indemnification agreements with its
directors and executive officers and intends to enter into indemnification
agreements with any new directors and executive officers in the future.


ITEM 16.       EXHIBITS.

Exhibit No.
- -----------

  5.1     Opinion of Wilson Sonsini Goodrich & Rosati, Professional Corporation.
 23.1     Consent of Price Waterhouse LLP.
 23.2     Consent of Counsel (included in Exhibit 5.1).
 24.1     Power of Attorney (included on page II-4).
 27.1     Restated Financial Data Schedule.
 27.2     Restated Financial Data Schedule.
 27.3     Restated Financial Data Schedule.

ITEM 17.       UNDERTAKINGS.

        (a).   UNDERTAKING PURSUANT TO RULE 415 OFFERING.

               The undersigned registrant hereby undertakes:

               (1) To file, during any period in which offers or sales are being
        made, a post-effective amendment to this Registration Statement to
        include any material information with respect to the plan of
        distribution not previously disclosed in the registration statement or
        any material change to such information in the registration statement.

               (2) That, for the purpose of determining any liability under the
        Securities Act of 1933, each such post-effective amendment shall be
        deemed to be a new registration statement relating to the securities
        offered therein, and the offering of such securities at that time shall
        be deemed to be the initial bona fide offering thereof.

               (3) To remove from registration by means of a post-effective
        amendment any of the securities being registered which remain unsold at
        the termination of the offering.

               The undersigned registrant hereby undertakes that, for purposes
of determining any liability under the Securities Act of 1933, each filing of
the registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Securities Exchange Act of 1934 (and, where applicable, each filing of an
employee benefit plan's annual report pursuant to Section 15(d) of the
Securities Exchange Act of 1934) that is incorporated by reference in the
Registration Statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.



                                      II-2

<PAGE>   14

               Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the registrant pursuant to the foregoing provisions or otherwise, the
registrant has been advised that in the opinion of the Securities Exchange
Commission such indemnification is against public policy as expressed in the
Securities Act of 1933 and is, therefore, unenforceable. In the event that a
claim for indemnification against such liabilities (other than the payment by
the registrant of expenses incurred or paid by a director, officer or
controlling person of the registrant in the successful defense of any action,
suit or proceeding) is asserted by such director, officer or controlling person
in connection with the securities being registered, the registrant will, unless
in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the
Securities Act of 1933 and will be governed by the final adjudication of such
issue.



                                      II-3

<PAGE>   15

                                   SIGNATURES


        Pursuant to the requirements of the Securities Act of 1933, the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-3 and has duly caused this registration
statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of San Jose, State of California, on this May 11, 1998.

                                      KLA-TENCOR CORPORATION

                                          By:/s/
                                             -----------------------------------
                                             Kenneth Levy, Chairman of the Board


                                POWER OF ATTORNEY

        KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Kenneth Levy and Lisa C. Berry, and each
of them, their true and lawful attorneys and agents, with full power of
substitution, each with power to act alone, to sign and execute on behalf of the
undersigned any amendment or amendments to this Registration Statement on Form
S-3 and to perform any acts necessary in order to file such amendments, and each
of the undersigned does hereby ratify and confirm all that said attorneys and
agents, or their or his or her substitutes, shall do or cause to be done by
virtue hereof. Pursuant to the requirements of the Securities Act of 1933, as
amended, this Registration Statement has been signed by the following persons in
the capacities and on the dates indicated.


<TABLE>
<CAPTION>
         Signature                                      Title                                Date
         ---------                                      -----                                ----
<S>                                      <C>                                            <C>
/s/                                                                                     
- -----------------------------            Chairman of the Board and Director             May 11, 1998
Kenneth Levy                                                                            
                                                                                        
                                                                                        
/s/                                      Chief Executive Officer and Director           May 11, 1998
- -----------------------------            (Principal Executive Officer)                  
Jon D. Tompkins                                                                         
                                                                                        
                                                                                        
/s/                                      President, Chief Operating Officer and         May 11, 1998
- -----------------------------            Director                                       
Kenneth L. Schroeder                                                                    
                                                                                        
                                                                                        
/s/                                      Executive Vice President, and Chief            May 11, 1998
- -----------------------------            Financial Officer
Robert J. Boehlke                        (Principal Financial and Accounting
                                         Officer)                                       
                                                                                        
                                                                                        
/s/                                      Director                                       May 11, 1998
- -----------------------------                                                           
James W. Bagley                                                                         
                                                                                        
                                                                                        
/s/                                      Director                                       May 11, 1998
- -----------------------------
Edward W. Barnholt                                                                      
                                                                                        
                                                                                        
/s/                                      Director                                       May 11, 1998
- -----------------------------                                                           
Leo J. Chamberlain                                                                      
                                                                                        
                                                                                        
/s/                                      Director                                       May 11, 1998
- -----------------------------                                                           
Richard J. Elkus, Jr.                                                                   
</TABLE>



                                               II-4

<PAGE>   16



<TABLE>
<CAPTION>
        Signature                             Title                                       Date
        ---------                             -----                                       ----
<S>                                          <C>                                     <C> 
/s/                                          Director                                May 11, 1998
- -----------------------------
Dean O. Morton


/s/                                          Director                                May 11, 1998
- -----------------------------
Yoshio Nishi

/s/                                          Director                                May 11, 1998
- -----------------------------
Samuel Rubinovitz


/s/                                          Director                                May 11, 1998
- -----------------------------
Dag Tellefsen


/s/                                          Director                                May 11, 1998
- -----------------------------
Lida Urbanek
</TABLE>



                                      II-5

<PAGE>   17

                                         INDEX TO EXHIBITS




<TABLE>
<CAPTION>
 Exhibit
 Number                              Description
- ----------      ----------------------------------------------------------------
<S>             <C>
  5.1           Opinion of Wilson Sonsini Goodrich & Rosati, Professional
                Corporation.

  23.1          Consent of Price Waterhouse LLP.

  23.2          Consent of Counsel (included in Exhibit 5.1).

  24.1          Power of Attorney (included on page II-4).

  27.1          Restated Financial Data Schedule.

  27.2          Restated Financial Data Schedule.

  27.3          Restated Financial Data Schedule.

</TABLE>



                                      II-6


<PAGE>   1


                                                                     Exhibit 5.1



                                  May 11, 1998



KLA-Tencor Corporation
160 Rio Robles
San Jose, CA 95134


        RE:     REGISTRATION STATEMENT ON FORM S-3

Ladies and Gentlemen:

        We have examined the Registration Statement on Form S-3 to be filed by
you with the Securities and Exchange Commission on or about the date hereof (the
"Registration Statement") in connection with the registration under the
Securities Act of 1933, as amended, of up to 1,800,000 shares of your Common
Stock (the "Shares"). All of the Shares are issued and outstanding and may be
offered for sale for the benefit of the selling stockholders named in the
Registration Statement. We understand that the Shares are to be sold from time
to time on the Nasdaq National Market at prevailing prices or as otherwise
described in the Registration Statement. As your legal counsel, we have also
examined the proceedings taken by you in connection with the issuance of the
Shares. We assume that the consideration received by you in connection with each
issuance of Shares will include an amount in the form of cash, services rendered
or property that exceeds the greater of (i) the aggregate par value of such
Shares or (ii) the portion of such consideration determined by the Company's
Board of Directors to be "capital" for purposes of the Delaware General
Corporation Law.

        Subject to the foregoing, we are of the opinion that the Shares are
validly issued, fully paid and non-assessable.

        We consent to the use of this opinion as an exhibit to the Registration
Statement and further consent to the use of our name wherever appearing in the
Registration Statement, including the Prospectus constituting a part thereof,
and any amendments thereto.


                                      Very truly yours,

                                      WILSON SONSINI GOODRICH & ROSATI
                                      Professional Corporation


                                      /s/ WILSON SONSINI GOODRICH & ROSATI




<PAGE>   1


                                                                    Exhibit 23.1


                       CONSENT OF INDEPENDENT ACCOUNTANTS


We hereby consent to the incorporation by reference in the Prospectus
constituting part of this Registration Statement on Form S-3 of our report dated
July 28, 1997, which appears on page 30 of the 1997 Annual Report to
Stockolders of KLA-Tencor Corporation, which is incorporated by reference in
KLA-Tencor's Annual Report on Form 10-K for the year ended June 30, 1997. We
also consent to the reference to us under the heading "Experts" in such
Prospectus.

Price Waterhouse LLP
San Jose, California
May 8, 1998




<TABLE> <S> <C>

<ARTICLE> 5
<RESTATED> 
       
<S>                             <C>
<PERIOD-TYPE>                   YEAR
<FISCAL-YEAR-END>                          JUN-30-1997
<PERIOD-START>                             JUL-01-1996
<PERIOD-END>                               JUN-30-1997
<CASH>                                         348,831
<SECURITIES>                                   338,418
<RECEIVABLES>                                  269,291
<ALLOWANCES>                                         0
<INVENTORY>                                    174,634
<CURRENT-ASSETS>                               860,007
<PP&E>                                         208,078
<DEPRECIATION>                                  90,483
<TOTAL-ASSETS>                               1,343,307
<CURRENT-LIABILITIES>                          324,751
<BONDS>                                              0
                                0
                                          0
<COMMON>                                       458,308
<OTHER-SE>                                     556,305
<TOTAL-LIABILITY-AND-EQUITY>                 1,343,307
<SALES>                                      1,031,824
<TOTAL-REVENUES>                             1,031,824
<CGS>                                          471,910
<TOTAL-COSTS>                                  471,910
<OTHER-EXPENSES>                               414,082
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                               1,959
<INCOME-PRETAX>                                173,979
<INCOME-TAX>                                    68,583
<INCOME-CONTINUING>                            105,396
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                   105,396
<EPS-PRIMARY>                                     1.29
<EPS-DILUTED>                                     1.24
        

</TABLE>

<TABLE> <S> <C>

<ARTICLE> 5
<RESTATED> 
       
<S>                             <C>
<PERIOD-TYPE>                   YEAR
<FISCAL-YEAR-END>                          JUN-30-1996
<PERIOD-START>                             JUL-01-1995
<PERIOD-END>                               JUN-30-1996
<CASH>                                         309,995
<SECURITIES>                                   158,480
<RECEIVABLES>                                  310,077
<ALLOWANCES>                                         0
<INVENTORY>                                    197,803
<CURRENT-ASSETS>                               869,709
<PP&E>                                         177,085
<DEPRECIATION>                                  72,248
<TOTAL-ASSETS>                               1,157,919
<CURRENT-LIABILITIES>                          278,312
<BONDS>                                              0
                                0
                                          0
<COMMON>                                       426,430
<OTHER-SE>                                     444,569
<TOTAL-LIABILITY-AND-EQUITY>                 1,157,919
<SALES>                                      1,094,492
<TOTAL-REVENUES>                             1,094,492
<CGS>                                          469,681
<TOTAL-COSTS>                                  469,681
<OTHER-EXPENSES>                               328,545
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                                   0
<INCOME-PRETAX>                                314,100
<INCOME-TAX>                                   117,466
<INCOME-CONTINUING>                            196,634
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                   196,634
<EPS-PRIMARY>                                     2.42
<EPS-DILUTED>                                     2.34
        

</TABLE>

<TABLE> <S> <C>

<ARTICLE> 5
<RESTATED> 
       
<S>                             <C>
<PERIOD-TYPE>                   YEAR
<FISCAL-YEAR-END>                          JUN-30-1995
<PERIOD-START>                             JUL-01-1994
<PERIOD-END>                               JUN-30-1995
<CASH>                                         259,027
<SECURITIES>                                   126,013
<RECEIVABLES>                                  223,307
<ALLOWANCES>                                         0
<INVENTORY>                                    114,061
<CURRENT-ASSETS>                               636,985
<PP&E>                                         104,132
<DEPRECIATION>                                  39,639
<TOTAL-ASSETS>                                 848,167
<CURRENT-LIABILITIES>                          185,660
<BONDS>                                              0
                                0
                                          0
<COMMON>                                       407,391
<OTHER-SE>                                     244,831
<TOTAL-LIABILITY-AND-EQUITY>                   848,167
<SALES>                                        695,950
<TOTAL-REVENUES>                               695,950
<CGS>                                          299,571
<TOTAL-COSTS>                                  299,571
<OTHER-EXPENSES>                               239,770
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                                   0
<INCOME-PRETAX>                                167,026
<INCOME-TAX>                                    62,215
<INCOME-CONTINUING>                            104,811
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                   104,811
<EPS-PRIMARY>                                     1.40
<EPS-DILUTED>                                     1.34
        

</TABLE>


© 2022 IncJournal is not affiliated with or endorsed by the U.S. Securities and Exchange Commission