AXCELIS TECHNOLOGIES INC

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934 (Amendment No. )

Filed by the Registrant☒

Filed by a Party other than the Registrant☐

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☐ Preliminary Proxy Statement

☐Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

☒ Definitive Proxy Statement

☐ Definitive Additional Materials

☐ Soliciting Material under§240.14a-12

Axcelis Technologies, Inc.

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(Name of Registrant as Specified in Its Charter)

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(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

☒ No fee required.

☐ Fee paid previously with preliminary materials.

☐ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a6(i)(1) and 0-11.

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

To Be Held May 5, 2026

The 2026 annual meeting of the stockholders of Axcelis Technologies, Inc., a Delaware corporation, will be held at the offices of the Company at 108 Cherry Hill Drive, Beverly, Massachusetts, at 11:00 a.m. on Tuesday, May 5, 2026 for the following purposes:

To elect as directors eight nominees to serve until the 2027 annual meeting of stockholders, with the Axcelis Board of Directors’ recommended director candidates named in the attached proxy statement.

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To ratify, by an advisory vote, the appointment of our independent registered public accounting firm to audit our financial statements for the year ending December 31, 2026.

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To approve, by an advisory vote, the 2025 compensation of our named executive officers.

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To transact such other business as may properly come before the meeting or any adjournment thereof.

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These business items are described more fully in the proxy statement accompanying this Notice.

Only stockholders of record at the close of business on March 12, 2026 will be entitled to vote at the annual meeting or at any adjournment.

By order of the Board of Directors,

Dated: March 31, 2026 Eileen J. Evans, Secretary

Stockholders should bring identification and, after checking in with the Security Desk in the

building lobby, they will be directed to the meeting room