[PALMER & DODGE LLP LOGO]
                   111 HUNTINGTON AVENUE AT PRUDENTIAL CENTER
                             BOSTON, MA 02199-7613




                                                              March 29, 2002


Axcelis Technologies, Inc.
55 Cherry Hill Drive
Beverly, Massachusetts 01915


         We are rendering this opinion in connection with the Registration
Statement on Form S-3 (the "Registration Statement") filed by Axcelis
Technologies, Inc. (the "Company") with the Securities and Exchange Commission
under the Securities Act of 1933, as amended, on or about the date hereof. The
Registration Statement relates to the registration of up to $125,000,000 in
aggregate principal amount of 4 1/4% Convertible Subordinated Notes Due 2007
(the "Notes") and the shares of Axcelis Technologies, Inc. common stock, $0.001
par value per share, issuable upon conversion of the Notes (the "Conversion
Shares"). The Notes were issued by the Company pursuant to an Indenture dated as
of January 15, 2002 (the "Indenture") between the Company and State Street Bank
and Trust Company, as trustee. We understand that the Notes and Conversion
Shares are to be offered and sold from time to time by the holders named in the
prospectus forming part of the Registration Statement (the "Prospectus") in the
manner described in the Prospectus.

         We have acted as the Company's counsel in connection with the
preparation of the Registration Statement and are familiar with the actions
taken by the Company in connection with the initial sale of the Notes. We have
examined such documents as we consider necessary to render this opinion.

         The Indenture and the Notes are governed by the law of the State of New
York and, therefore, in rendering our opinion as to the validity and binding
effect of the Indenture and the Notes, we have relied on an opinion of New York
counsel with respect to matters of New York law. Except to the extent of such
reliance, the opinions rendered herein are limited to the Delaware General
Corporation Law, including applicable provisions of the Delaware Constitution
and reported judicial decisions interpreting these laws, and the Federal law of
the United States.

         Based upon and subject to the foregoing, we are of the opinion that:

         1. The Notes are, and when sold pursuant to the Prospectus will be,
valid and binding obligations of the Company, subject to applicable bankruptcy,
insolvency or similar laws affecting creditors' rights generally and general
principles of equity.

         2. The 6,250,000 Conversion Shares being registered have been duly
authorized and, when issued and delivered upon conversion of the Notes in
accordance with the terms of the Indenture, will be validly issued, fully paid
and nonassessable.



March 29, 2002
Page 2





         We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to our firm under the caption "Legal
Matters" in the Prospectus.

                                                     Very truly yours,

                                                     /s/ PALMER & DODGE LLP