Exhibit 23.1 CONSENT OF ERNST & YOUNG LLP We consent to the incorporation by reference in the Registration Statement (Form S-8) pertaining to the Axcelis Technologies, Inc. 2000 Stock Plan, of our report dated May 3, 2000, except for Note 19, as to which the date is June 14, 2000, with respect to the combined financial statements of Axcelis Technologies, Inc. included in its Prospectus, filed on July 11, 2000 with the Securities and Exchange Commission. /s/ Ernst & Young LLP Boston, Massachusetts October 31, 2000