Exhibit 10.21

CYMER, INC.  REDUCTION IN FORCE SEPARATION BENEFITS PLAN

SECTION 1.    PURPOSE

This Plan (as defined herein) is designed to provide separation pay and benefits to Eligible Employees (as defined herein) of the Company (as defined herein)
pursuant to the terms and conditions set forth in this Plan. The Plan is intended to be an employee welfare benefit plan, as defined in Section 3(1) of ERISA (as defined herein) and shall be
interpreted to effectuate this intent. This document shall serve as both a plan document and summary plan description for purposes of Title I of ERISA.

SECTION 2.    EFFECTIVE DATE AND TERM

Any and all of the Company's policies and practices regarding severance benefits or similar payments upon employment termination or position elimination with
respect to Eligible Employees, other than written employment or separation agreements with the Company that provide severance benefits executed prior to the effective date of this Plan, are hereby
superseded by this Plan, effective as of April 1, 2001. This plan will remain in effect for the period from April 1, 2001 through March 31, 2002, at which time it shall
automatically terminate and cease to be in effect, unless earlier renewed by the Board of Directors of Cymer, Inc.

SECTION 3.    DEFINITIONS

(a)    "Base Pay"means the Eligible Employee's wages earned on a weekly basis determined as of the Eligible
Employee's Termination Date (as defined herein), excluding bonuses and commissions, and, if paid hourly, is based on the average number of regularly scheduled hours worked per week for the three
months preceding the Termination Date.

(b)    "Board"means the Board of Directors of Cymer, Inc.

(c)    "Cause"means, with respect to a particular Eligible Employee: (i) fraud, misappropriation,
embezzlement or other act of misconduct against the Company; (ii) conviction of a felony; (iii) violation of any rules or regulations of any governmental or regulatory body which has an
adverse effect on the Company; (iv) a material breach of the terms of the Eligible Employee's employment obligations, or a breach of the Eligible Employee's duty not to engage in any
transaction that represents, directly or indirectly, self-dealing with the Company or any of the Company's affiliates, which has not been approved by the Company; (v) unsatisfactory
performance; (vi) violation of state or federal law in connection with the Eligible Employee's performance of his/her job; (vii) a leave of absence exceeding the period allowed by
contract, policy or applicable law; or (viii) circumstances beyond the Company's control including, but not limited to, fire, flood, explosion, bombing, earthquake, and civil unrest.
Notwithstanding the foregoing, termination of the Eligible Employee's employment due to death or disability shall not be considered termination for Cause.

(d)    "Committee"means the Committee of the Board (and any delegatee(s) of such Committee) established by the
Board to administer this Plan in accordance with its terms.

(e)"Company"means Cymer, Inc. and its subsidiaries.

(f)    "Comparable Position"means any position with the Company, regardless of title and responsibilities, that is
located within [50] miles of the location at which the Eligible Employee was performing his or her duties immediately prior to his or her Termination Date and the compensation

1

---

for such position is within fifteen percent (15%) of Eligible Employee's Base Pay as of the Eligible Employee's Termination Date.

(g)    "Eligible Employee"means any non-temporary, full-time [or
part-time employee] (i.e., working at least 20 hours per week) of the Company (specifically excluding any individual who is not treated by the Company as a common law
employee without regard to the characterization or recharacterization of such individual's status by any court or governmental agency), who is paid from the Company's United States payroll and who has
been notified by the Company that he or she is subject to Involuntary Termination Without Cause as a result of a Reduction in Force and who has not been offered a Comparable Position with the Company.
Employees who do not return to work following a leave of absence prior to a Reduction in Force and/or who begin receiving Long-Term Disability benefits are not eligible for the benefits
provided herein.

(h)    "ERISA"means the Employee Retirement Income Security Act of 1974, as amended.

(i)    "Involuntary Termination Without Cause"means an employee's dismissal or discharge by the Company for a
reason other than for Cause. The termination of an employee's employment will not be deemed to be an "Involuntary Termination Without Cause" if such termination either occurs as a result of the
employee's death or disability, or is the result of the employee's resignation for any reason (including retirement).

(j)    "Participant"means an Eligible Employee who has fulfilled the requirements of Section 4 herein.

(k)    "Plan"means this Cymer, Inc. 2000 Separation Benefits Plan, as set forth in this instrument and as
amended from time to time.

(l)    "Reduction in Force"means the Involuntary Termination without Cause (as defined in the Plan) of the
employment of two (2) or more [full-time or part-time] employees of the Company [within a ninety (90) day period]
as a result of lack of work, lack of funds, economic slowdowns, technological or structural changes in the Company's operations, or business, operational or other circumstances which necessitate a
reduction in the number of employees as a means of ensuring the financial health, efficiency and viability of the Company on a short-term or long-term basis. The determination
as to whether a not a Reduction in Force has occurred under particular circumstances shall be made by the Committee in its sole and exclusive discretion.

(m)    "Service Date"means the Eligible Employee's first date of employment with the Company or, if rehired by the
Company, the adjusted date of employment based on the date of rehire.

(n)    "Termination Date"means the date of the Eligible Employee's Involuntary Termination Without Cause.

(o)    "Years of Service"means the number of full years (i.e., a period of twelve complete months) of service
completed by the Eligible Employee from the Service Date to the Termination Date.

SECTION 4.    DEPARTURE AND ENTITLEMENT PROCEDURE.

As a condition to receiving the severance benefits described in Section 5, the Eligible Employee must deliver to the Director, Human Resources, or his or
her designee an effective Release and return all Company property within five (5) days of the Eligible Employee's Termination Date. The Release is attached hereto as Exhibit A and is
incorporated herein by reference. Employees shall receive the Release upon the distribution of this Plan document.

2

---

SECTION 5.    PARTICIPATION AND BENEFITS.



POSITION LEVEL

OUTPLACEMENT SERVICESDirector

4 months Base Salary plus
1 week Base Salary
per Year of ServiceManager

2 months Base Salary plus
1 week Base Salary
per Year of ServiceSenior Level Professional,
Individual Contributor

2 months Base Salary plus
1 week Base Salary
per Year of ServiceSupervisor

1 month Base Salary plus
1 week Base Salary
per Year of ServiceExempt or Technical Employee

1 month Base Salary plus
1 week Base Salary
per Year of ServiceNon-Exempt Employee

1 week Base Salary
per Year of Service
(minimum 3 weeks Base Salary)




POSITION LEVEL

OUTPLACEMENT SERVICESDirector

3-monthsManager

1-monthSenior Level Professional,
Individual Contributor

1-monthSupervisor

2-day workshopExempt or Technical Employee

2-day workshopNon-Exempt Employee

2-day workshop




3

---



(b)    Voluntary Resignation/Termination for Cause.Notwithstanding any other provision of the Plan to the
contrary, in no event shall an Eligible Employee receive any payment hereunder if his or her termination is for Cause or occurs as a result of his or her death or disability, or is the result of his
or her resignation for any reason (including retirement).

(c)    "At Will" Employment.No provision of this Plan alters a Participant's "at will" employment status with the
Company.

(d)    Offsets/Withholding.Notwithstanding any other provision of the Plan to the contrary, severance benefits
received pursuant to this Plan shall be subject to offset(s) and withholding as set forth below.



The
Committee shall determine in its sole and exclusive judgment and discretion whether and in what manner the provisions of this subsection 5(d) shall apply.

(e)    Loss and Reduction of Benefits.Notwithstanding any other provision of the Plan to the contrary, severance
benefits under this Plan shall terminate and/or shall be reduced as set forth below.



4

---



The
Committee shall determine in its sole and exclusive judgment and discretion whether and in what manner the provisions of this subsection 5(e) shall apply

(f)    Limitation on Employee rights.The Plan shall not give any employee of the Company the right to be retained
in the service of the Company or to interfere with or restrict the right of the Company to discharge any employee at any time, for any reason, with or without Cause.

SECTION 6.    ADMINISTRATION AND OPERATION OF THE PLAN

(a)    Plan Sponsor and Administrator.The Company is the "Plan Sponsor" and the "Plan Administrator" of the Plan
(as such terms are defined in ERISA) and shall have responsibility for complying with any reporting and disclosure rules applicable to the Plan under ERISA. In all other respects, except as provided
herein, the Plan shall be administered and operated by the Committee and its delegatee(s). The Committee is empowered to construe and interpret the provisions of the Plan and to decide all questions
of eligibility for benefits under this Plan and shall make such determinations in its sole and absolute discretion which shall be conclusive and binding upon all persons. The Committee may at any time
delegate to any other named person or body, or reassume therefrom, any of its fiduciary responsibilities or administrative duties with respect to this Plan.



SECTION 7.    CLAIMS, INQUIRIES AND APPEALS

(a)    Applications for Benefits and Inquiries.Except as otherwise provided in this subsection 7(a), no
application for benefits is required to receive benefits under this Plan. If an individual believes that he or she has been wrongfully denied any benefits under this Plan, such individual shall submit
an application for benefits signed and in writing to: Corporate Human Resources, Cymer, Inc., 16750 Via Del Campo Court, San Diego, California 92127, who shall forward such request to the
Committee.

(b)    Denial of Claims.If any application for benefits is denied in whole or in part, the Committee must notify
the claimant, in writing, of the denial of the application, and of the claimant's right to review of the denial. The written notice of denial will be set forth in a manner designed to be understood,
and will include specific reasons for the denial, specific references to the Plan provision upon which the denial is based, a description of any information or material that the Committee needs to
complete the review and an explanation of the Plan's review procedure.

5

---



(c)    Request for Review.The claimant (or the claimant's authorized representative) may appeal a denied benefit
claim by submitting a written request for a review to: Corporate Human Resources, Cymer, Inc., 16750 Via Del Campo Court, San Diego, California 92127, who shall forward such request to the
Committee.



(d)    Decision on Review.The Committee will act on each request for review within sixty (60) days after
receipt of the request, unless special circumstances require an extension of time (not to exceed an additional sixty (60) days) for processing the request for a review. If an extension for
review is required, written notice of the extension will be furnished within the initial 60-day period. The Committee will give written notice of its decision to the applicant. In the
event that the Committee confirms the denial of the application for benefits in whole or in part, the notice will outline the specific Plan provisions upon which the decision is based. If written
notice of the Committee's decision is not given within the time prescribed above, the application will be deemed denied on review.

(e)    Exhaustion of Remedies.No legal action for benefits under the Plan may be brought until (i) a
written application for benefits has been submitted in accordance with the procedures described above, (ii) the person claiming benefits has been notified by the Committee that the application
is denied (or the application is deemed denied due to the Committee's failure to act on it within the time prescribed), (iii) a written request for a review of the application has been
submitted in accordance with the appeal procedure described above and (iv) the person appealing the denial has been notified in writing that the Committee has denied the appeal (or the appeal
is deemed to be denied due to the Committee's failure to take any action on the claim within the time prescribed).

SECTION 8.    BASIS OF PAYMENTS TO AND FROM THE PLAN

All benefits under the Plan shall be paid by the Company. The Plan shall be unfunded and benefits hereunder shall be paid only from the general assets of the
Company.

6

---

SECTION 9.    AMENDMENT AND TERMINATION

The Company reserves the right to amend or terminate this Plan at any time;provided, however,that no amendment
or termination shall diminish benefits to which a Participant is currently entitled under this Plan. Any termination, modification or other amendment of the Plan shall be only in writing and signed by
the President and Chief Operating Officer, Cymer, Inc..

SECTION 10.    NON-ALIENATION OF BENEFITS

No Plan benefit may be anticipated, alienated, sold, transferred, assigned, pledged, encumbered or charged, and any attempt to do so will be void.

SECTION 11.    LEGAL CONSTRUCTION

This Plan shall be interpreted in accordance with ERISA and, to the extent not preempted by ERISA, with the laws of the State of California.

SECTION 12.    OTHER PLAN INFORMATION

Plan Identification Number:The Plan ID #501

Employer Identification Number:33-0175463

Ending of the Plan's Fiscal Year:December 31.

Agent for the Service of Legal Process:The Plan's agent for service of legal process is: Sr. Vice President, Human Resources,
Cymer, Inc., 16750 Via Del Campo Court, San Diego, California 92127.

SECTION 13.    STATEMENT OF ERISA RIGHTS AND DUTIES

(a)Participants in this Plan (which is a welfare benefit plan sponsored by the Company) are entitled to certain rights and
protections under ERISA, including the right to:



(b)In addition to creating rights for Plan participants, ERISA imposes duties upon the people responsible for the operation
of the employee benefit plan. The people who operate the Plan, called "fiduciaries" of the Plan, have a duty to do so prudently and in the interest of Plan participants and beneficiaries.

(c)No one, including the Company or any other person, may fire any person or otherwise discriminate against him or her in
any way to prevent him or her from obtaining a Plan benefit or exercising rights under ERISA. If a claim for a Plan benefit is denied in whole or in part, the claimant must receive a written
explanation of the reason for the denial. A claimant has the right to have the Plan review and reconsider his or her claim.

(d)Under ERISA, there are steps an employee can take to enforce the above rights. For instance, if an employee request
materials from the Plan and does not receive them within 30 days, he

7

---

or she may file suit in a federal court. In such a case, the court may require the Plan Administrator to provide the materials and pay up to $100 a day until the employee receives the materials,
unless the materials were not sent because of reasons beyond the control of the Plan Administrator. If an employee has a claim for benefits that is denied or ignored, in whole or in part, he or she
may file suit in a state or federal court. If it should happen that the Plan fiduciaries misuse the Plan's money, or if an employee is discriminated against for asserting his or her rights, he or she
may seek assistance from the U.S. Department of Labor, or file suit in a federal court. The court will decide who should pay court costs and legal fees. If he or she is successful, the court may order
the person sued to pay these costs and fees. If he or she is unsuccessful, the court may order him or her to pay these costs and fees, for example, if it finds the claim is frivolous.

(e)If an employee has any questions about this statement or about his or her rights under ERISA, he or she should contact
the nearest office of the Pension and Welfare Benefits Administration, U.S. Department of Labor, listed in the telephone directory, or the Division of Technical Assistance and Inquiries, Pension and
Welfare Benefit Administration, U.S. Department of Labor, 200 Constitution Avenue N.W., Washington, D.C. 20210.

8

---

QuickLinks