Exhibit 10.1

THIRTEENTH AMENDMENT

OF

ENTEGRIS, INC.

401(k) SAVINGS AND PROFIT SHARING PLAN

(2005 Restatement)

Entegris, Inc., a Delaware corporation, has heretofore established and maintains
a profit sharing plan (the “Plan”) which, in most recent amended and restated
form, is embodied in a document effective August 5, 2005, and entitled
“ENTEGRIS, INC. 401(k) SAVINGS AND PROFIT SHARING PLAN (2005 Restatement),” as
amended by twelve amendments (collectively, the “Plan Statement”). The Plan
Statement is hereby further amended in the following respect:

1. COMPLIANCE WITH HEART ACT. Effective January 1, 2009, Section 1.2 of the Plan
Statement shall be amended to read in full as follows:

1.2. Compliance With Uniformed Services Employment and Reemployment Rights Act
of 1994 and Heroes Earnings Assistance and Relief Tax Act of 2008. Effective for
veterans rehired on or after December 12, 1994, and notwithstanding any
provision of the Plan Statement to the contrary, contributions, benefits or
service credits, if any, will be provided in accordance with section 414(u) of
the Code. Effective January 1, 2009, and notwithstanding any provision of the
Plan Statement to the contrary, (i) differential pay (as defined in
section 3401(h)(2) of the Code) shall be included in compensation that is used
to determine benefits, and (ii) the death after 2006 of a Participant during
qualified military service (as defined in section 414(u)(5) of the Code) will be
treated as death while in the employment of the Employer and all Affiliates for
purposes of any benefits (other than benefit accruals related to the period of
qualified military service) to which the Participant’s survivors would have been
entitled had the Participant resumed employment and then terminated employment
on account of death.

2. SAVINGS CLAUSE. Save and except as hereinabove expressly amended, the Plan
Statement shall continue in full force and effect.