Exhibit 10.15

KLA-TENCOR CORPORATION

PERFORMANCE BONUS PLAN

          1)          Purposes of the Plan.  The Plan is intended to increase
stockholder value and the success of the Company by motivating Participants
(1) to perform to the best of their abilities, and (2) to achieve the Company’s
objectives.  The Plan’s goals are to be achieved by offering Participants the
opportunity to earn incentive awards for the achievement of goals relating to
the performance of the Company.  The Plan is intended to permit the payment of
bonuses that qualify as performance-based compensation under section 162(m) of
the Code.

          2)          Definitions.

                       (a)           “Actual Award” means as to any Performance
Period, the actual cash award (if any) payable to the Participant for a
Performance Period.  Each Actual Award is determined by a Payout Formula for a
Performance Period, subject to the Committee’s authority under Section 8(a) to
eliminate or reduce the Actual Award otherwise payable.

                       (b)          “Base Salary” means any Performance Period,
the Participant’s earned salary during that Performance Period.  Such Base
Salary shall be before both (a) deductions for taxes or benefits, and
(b) deferrals of compensation pursuant to Company-sponsored plans.

                       (c)          “Board” means the Board of Directors of the
Company.

                       (d)          “Bookings” means net purchase orders
received from third parties.

                       (e)          “Cash Flow” means cash generated from
operating activities.

                       (f)          “Code” means the Internal Revenue Code of
1986, as amended.

                       (g)          “Committee” means the Compensation Committee
of the Board, or a sub-committee of the Compensation Committee, which shall
consist solely of two or more members of the Board who are not employees of the
Company and who otherwise qualify as “outside directors” within the meaning of
Section 162(m).

                       (h)          “Company” means KLA-Tencor Corporation.

                       (i)          “Determination Date” means the latest
possible date that will not jeopardize a Target Award or Actual Award’s
qualification as Performance-Based Compensation.

                       (j)          “Fiscal Year” means a fiscal year of the
Company.

                       (k)          “Maximum Award” means as to any Participant
for any Performance Period, $4 million.

                       (l)          “Participant” means an eligible executive or
key employee of the Company participating in the Plan for a Performance Period.

                       (m)          “Payout Formula” means as to any Performance
Period, the formula or payout matrix established by the Committee pursuant to
Section 7 in order to determine the Actual Awards (if any) to be paid to
Participants.  The formula or matrix may differ from Participant to Participant.

                       (n)          “Performance-Based Compensation” means
compensation that is intended to qualify as “performance-based compensation”
within the meaning of Section 162(m).

                       (o)          “Performance Goals” means the goal(s) (or
combined goal(s)) determined by the Committee (in its discretion) to be
applicable to a Participant for a Target Award for a Performance Period.  As
determined by the Committee, the Performance Goals applicable to an Actual Award
and/or Target Award may provide for a targeted level or levels of achievement
using one or more of the following measures: (i) Bookings, (ii) Cash Flow,
(iii) Pre-Tax Margin, (iv) Profit, (v) Return on Assets, (vi) Return on Invested
Capital, and/or (vii) Revenue.  Performance Goals may differ from Participant to
Participant, Performance Period to Performance Period and from award to award.  
Any Performance Goal may be tested or measured, as applicable, (1) in absolute
terms, (2) in relative terms (including, but not limited, the passage of time
and/or against other companies or financial metrics), (3) on a per share and/or
share per capita basis, (4) against the performance of the Company as a whole or
against particular segments or products of the Company, and/or (5) on a pre-tax
or after-tax basis.  On or prior to the Determination Date, the Committee shall
determine whether any element(s) (for example, but not by way of limitation, the
effect of mergers or acquisitions) shall be included in or excluded from the
calculation of any Performance Goal with respect to any Participants (whether or
not such determinations result in any Performance Goal being measured on a basis
other than generally accepted accounting principles).

                       (p)          “Performance Period” means any Fiscal Year
or such other period shorter or longer than a Fiscal Year, as determined by the
Committee in its sole discretion.  However, no Performance Period shall have a
duration longer than three Fiscal Years.  Also, with respect to any Participant,
no more than three Performance Periods shall exist at any one time.

                       (q)          “Plan” means this Performance Bonus Plan, as
amended from time to time.

                       (r)           “Pre-Tax Margin” means the percentage equal
to Profit, divided by Revenue.

                       (s)          “Profit” means net income.

                       (t)          “Return on Assets” means the percentage
equal to Profit, divided by average net assets.

                       (u)          “Return on Invested Capital” means the
percentage equal to Profit, divided by average invested capital.

                       (v)          “Revenue” means net sales to third parties.

                       (w)          “Section 162(m)” means Section 162(m) of the
Code, or any successor to Section 162(m), as that Section may be interpreted
from time to time by the Internal Revenue Service, whether by regulation, notice
or otherwise.

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                       (x)          “Target Award” means the target award
payable under the Plan to a Participant for the Performance Period, expressed as
a percentage of his or her Base Salary or a specific dollar amount, as
determined by the Committee in accordance with Section 6.

          3)          Plan Administration.

                       a)          The Committee shall be responsible for the
general administration and interpre-tation of the Plan and for carrying out its
provisions.  Subject to the requirements for qualifying compensation as
Performance-Based Compensation, the Committee may delegate specific
administrative tasks to Company employees or others as appropriate for proper
administra-tion of the Plan.  Subject to the limitations on Committee discretion
imposed under Section 162(m), the Committee shall have such powers as may be
necessary to discharge its duties hereunder, including, but not by way of
limitation, the following powers and duties, but subject to the terms of the
Plan:

                                    i)          discretionary authority to
construe and interpret the terms of the Plan, and to determine eligibility,
Actual Awards and the amount, manner and time of payment of any Actual Awards
hereunder;

                                    ii)         to prescribe forms and
procedures for purposes of Plan participation and distribution of Actual Awards;
and

                                    iii)        to adopt rules, regulations and
bylaws and to take such actions as it deems necessary or desirable for the
proper administration of the Plan.

                       b)          Any rule or decision by the Committee that is
not inconsistent with the provisions of the Plan shall be conclusive and binding
on all persons, and shall be given the maximum deference permitted by law.

          4)          Eligibility.  The employees eligible to participate in the
Plan for a given Performance Period shall be employees of the Company who are
designated by the Committee in its sole discretion.  No person shall be
automatically entitled to participate in the Plan.

          5)          Performance Goal Determination.  The Committee, in its
sole discretion, shall establish the Performance Goals for each Participant for
the Performance Period.  Such Performance Goals shall be set forth in writing on
or prior to the Determination Date. 

          6)          Target Award Determination.  The Committee, in its sole
discretion, shall establish a Target Award for each Participant.  Each
Participant’s Target Award shall be determined by the Committee in its sole
discretion, and each Target Award shall be set forth in writing prior to the
Determination Date.

          7)          Determination of Payout Formula or Formulae.  On or prior
to the Determination Date, the Committee, in its sole discretion, shall
establish a Payout Formula or Formulae for purposes of determining the Actual
Award (if any) payable to each Participant.  Each Payout Formula shall (a) be
set forth in writing prior to the Determination Date, (b) be based on a
comparison of actual performance to the Performance Goals, (c) provide for the
payment of a Participant’s Target Award if the Performance Goals for the
Performance Period are achieved, and (d) provide for an Actual Award greater
than or less than the Participant’s Target Award, depending upon the extent to
which actual performance exceeds or falls below the Performance Goals. 
Notwithstanding the preceding, in no event shall a Participant’s Actual Award
for any Performance Period exceed the Maximum Award.

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          8)          Determination of Awards; Award Payment.

                       a)          Determination and Certification.  After the
end of each Performance Period, the Committee shall certify in writing (for
example, in its meeting minutes) the extent to which the Performance Goals
applicable to each Participant for the Performance Period were achieved or
exceeded.  The Actual Award for each Participant shall be deter-mined by
applying the Payout Formula to the level of actual performance that has been
certified by the Committee.  Notwithstanding any contrary provision of the Plan,
the Committee, in its sole discretion, may (a) eliminate or reduce the Actual
Award payable to any Participant below that which other-wise would be payable
under the Payout Formula, and (b) determine whether or not a Participant will
receive an Actual Award in the event the Participant incurs terminates his or
her employment with the Company prior to the date the Actual Award otherwise is
to be paid.

                       (b)          Right to Receive Payment.  Each Actual Award
that may become payable under the Plan shall be paid solely from the general
assets of the Company.  Nothing in this Plan shall be construed to create a
trust or to establish or evidence any Participant’s claim of any right to
payment of an Actual Award other than as an unsecured general creditor with
respect to any payment to which he or she may be entitled.

                       (c)          Form of Payment.  The Company shall pay all
Actual Awards in cash paid to the Participant.

                       (d)          Timing of Payments.  Except as provided in
Section 8(e), the Company shall distribute amounts payable to Participants as
soon as is practicable following the determination and written certification of
the Actual Award for a Performance Period, but in no event later than 90 days
after the end of the applicable Performance Period.

                       (e)          Deferral.  The Committee may defer payment
of, and apply a vesting schedule to, one or more Actual Awards, or any
portion(s) thereof, as the Committee (in its sole discretion) determines, except
that no such vesting schedule may exceed four years.  In addition, the
Committee, in its sole discretion, may permit a Participant to defer receipt of
the payment of cash that would otherwise be delivered to a Participant under the
Plan.  Any such deferral elections shall be subject to such rules and procedures
as shall be determined by the Committee in its sole discretion.

          9)          Term of Plan.  Subject to approval of the Company’s
stockholders at the Company’s 2005 Annual Meeting, the Plan shall become
effective on July 1, 2005.  The Plan shall continue until terminated under
Section 10 of the Plan.

          10)        Amendment and Termination of the Plan.  The Committee may
amend, modify, suspend or terminate the Plan, in whole or in part, at any time,
including the adoption of amendments deemed necessary or desirable to correct
any defect or to supply omitted data or to reconcile any inconsistency in the
Plan or in any Actual Award granted hereunder; provided, however, that no
amend-ment, alteration, suspension or discontinuation shall be made that would
(i) impair any payments to Participants made prior to such amendment,
modification, suspension or termination, unless the Committee has made a
determination that such  amendment or modification is in the best interests of
all persons to whom Actual Awards have theretofore been granted; provided
further, however, that in no event may such an amendment or modification result
in an increase in the amount of compensation payable pursuant to such Actual
Award or (ii) cause compensation that is, or may become, payable here-under to
fail to qualify as Performance-Based Compensation.  To the extent necessary or
advisable under applicable law, including Section 162(m), Plan amendments shall
be subject to stockholder approval.  At no time before the actual distribution
of funds to Participants under the Plan shall any Participant accrue any vested
interest or right whatsoever under the Plan except as otherwise stated in this
Plan.

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          11)        Withholding.  Distributions pursuant to this Plan shall be
subject to all applicable federal and state tax and withholding requirements.

          12)        Employment.  This Plan does not constitute a contract of
employment or compensa-tion or impose on either the Participant or the Company
any obligation to retain the Participant as an employee.  This Plan does not
change the status of the Participant as an employee at will, the policies of the
Company regarding termination of employment, nor guarantee further continuing
participation in the Plan.

          13)        Successors.  All obligations of the Company under the Plan,
with respect to awards granted hereunder, shall be binding on any successor to
the Company,  whether the existence of such successor is the result of a direct
or indirect purchase, merger, consolidation, or otherwise, of all or
substantially all of the business or assets of the Company.

          14)        Indemnification.  Each person who is or shall have been a
member of the Committee, or of the Board, shall be indemnified and held harmless
by the Company against and from (a) any loss, cost, liability, or expense that
may be imposed upon or reasonably incurred by him or her in connection with or
resulting from any claim, action, suit, or proceeding to which he or she may be
a party or in which he or she may be involved by reason of any action taken or
failure to act under the Plan or any award, and (b) from any and all amounts
paid by him or her in settlement thereof, with the Company’s approval, or paid
by him or her in satisfaction of any judgment in any such claim, action, suit,
or proceeding against him or her, provided he or she shall give the Company an
opportunity, at its own expense, to handle and defend the same before he or she
undertakes to handle and defend it on his or her own behalf.  The foregoing
right of indemnification shall not be exclusive of any other rights of
indemnification to which such persons may be entitled under the Company’s
Certificate of Incorporation or Bylaws, by contract, as a matter of law, or
otherwise, or under any power that the Company may have to indemnify them or
hold them harmless.

          15)        Nonassignment.  The rights of a Participant under this Plan
shall not be assignable or transferable by the Participant except by will or the
laws of intestacy.

          16)        Governing Law.  The Plan shall be governed by the laws of
the State of California (without regard to its conflict of laws provisions).

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