<PAGE>

                                 EXHIBIT 10.21

Portions of this document have been omitted pursuant to a  request for
confidential treatment and such portions have been filed separately with the
Securities and Exchange Commissions. These portions are designated by the
symbol ***.


                              RESEARCH AGREEMENT

1.   PARTIES

     1.1  The parties to this Agreement are E. I. du Pont de Nemours and
     Company, having a place of business at 1007 Market Street, Wilmington, DE
     ("DuPont") and DuPont Photomasks, Inc., having a place of business at 131
     Old Settlers Blvd., Round Rock, TX ("DPI").

2.   BACKGROUND

     2.1  This Agreement covers a research project undertaken by DuPont at the
     request of DPI pursuant to a Research, Development and Consulting Agreement
     between DuPont and DPI effective on January 1, 1996.

3.   SCOPE

     3.1  DuPont shall provide research and materials development activity in
     the area of advanced photomask technology, such as photomasks, blanks and
     pellicles, as more specifically defined below.  Specifically DuPont will
     continue development of advanced phase shift mask technology and work to
     develop a material suitable for use as pellicles, particularly a 157 nm
     pellicle, and will support DPI's efforts to fabricate a pellicle using the
     developed material.  DuPont shall provide DPI with Milestone reports
     summarizing the activities of DuPont undertaken pursuant to this Agreement
     according to the attached schedule in Appendix A.

     3.2  By "Field" herein is meant "photomasks, blanks and pellicles" wherein
     these terms are defined as photomasks, photoblanks and pellicles, used in
     photolithography for microelectronic applications (including pellicles for
     optical markets).

     3.3  By "DuPont Materials" is meant materials developed by and supplied by
     DuPont to DPI pursuant to this program, and being evaluated in the Field
     pursuant to this Agreement, and any improvements to such materials
     developed by either party under this Agreement.  This definition is not
     intended to cover current commercial amorphous  fluoropolymers sold to DPI
     by DuPont.

     3.4  By "DuPont Technology" hereunder is meant process technology or know-
     how, being evaluated by DPI, in the Field, owned by DuPont.

4.   INTELLECTUAL PROPERTY

     4.1  DuPont shall own any and all inventions, discoveries, processes,
     improvements, ideas and

                                       1
<PAGE>

     like intellectual property relating to DuPont Materials under this
     agreement which are conceived and/or reduced to practice by either party
     during the course of this Agreement (collectively "DuPont Inventions"). In
     addition, DuPont shall own all inventions, discoveries, processes,
     improvements, ideas and like intellectual property that are conceived and
     reduced to practice solely by DuPont during the course of this Agreement,
     except as related to intellectual property covered in 4.2 below.

     4.2  DPI shall own any and all inventions, discoveries, processes,
     improvements, ideas and like intellectual property, that come about after
     the effective date of this Agreement, relating to pellicle end uses, where
     the invention, discovery, process, improvement, or idea is not dependent
     upon DuPont Materials, which are conceived and/or reduced to practice by
     either party during the course of this Agreement (collectively "DPI
     Inventions").  In addition, DPI shall own all inventions, discoveries,
     processes, improvements, ideas and like intellectual property. which are
     conceived and reduced to practice solely by DPI during the course of this
     Agreement, except as related to intellectual property covered in 4.1 above.

     4.3  DPI and DuPont shall jointly own all inventions, discoveries,
     processes, improvements, ideas and like intellectual property, except as
     related to DuPont Materials covered in 4.1 above and DPI Inventions and DPI
     inventions under 4.2, conceived and reduced to practice jointly during the
     course of this Agreement.

     4.4  DuPont shall have full authority, responsibility and discretion to
     prepare, file, prosecute and maintain patent applications and patents on
     inventions covered under subsection 4.1.  DuPont shall also have full
     authority, responsibility and discretion to prepare, file, prosecute and
     maintain any joint DuPont/DPI inventions covered under 4.3.  DPI agrees to
     provide DuPont with access to data and other information reasonably
     necessary for DuPont to prepare, file and prosecute patent applications on
     the Inventions and further agrees to execute such documents as are
     reasonably necessary to establish, transfer or perfect title to DuPont on
     inventions under 4.1 and to DuPont and DPI jointly on inventions under 4.3.

     4.5  DPI shall have full authority, responsibility and discretion to
     prepare, file, prosecute and maintain its sole patent applications and
     patents on inventions under subsection 4.2.  DuPont agrees to provide DPI
     with access to data and other information reasonably necessary for DPI to
     prepare, file and prosecute patent applications on the Inventions and
     further agrees to execute such documents as are reasonably necessary to
     establish, transfer or perfect title to such Inventions to DPI.

     4.6  DuPont grants DPI a royalty bearing, exclusive license (with the right
     to sub-license) for the life of the patents to use, import, export, sell
     and offer to sell, but not to make, any DuPont Materials supplied or
     developed under this Agreement, only in the Field.  DPI shall provide
     DuPont with a first right of refusal to provide DPI with all its
     requirements of DuPont Materials.  If DuPont accepts, DPI shall purchase
     all its requirements of any DuPont Materials under this Agreement from
     DuPont and DuPont shall supply such DuPont Materials to DPI in exchange for
     an agreed upon purchase price, such as is reasonable for such subject
     matter in the trade.  In addition, DPI agrees to pay DuPont a *** royalty,
     based upon the sale price, on the sale of any pellicles made using DuPont
     Materials under this Agreement.  In the event that DuPont is unable or
     unwilling to supply such DuPont Materials to DPI and if DPI desires to make
     such DuPont Materials for itself or have another, mutually agreed upon
     entity make the DuPont Materials for DPI, DPI shall pay to DuPont a ***
     royalty, based upon the sale price, on the sale of pellicles made using
     DuPont Materials.  In such case, DuPont shall make reasonable efforts

                                       2
<PAGE>

     to provide DPI with the necessary know-how to allow DPI or a third party to
     make the DuPont Materials. Should DPI sub-license a third party to utilize
     DuPont Material for use in pellicles, any such license shall include a
     provision such that DuPont gets a *** royalty on pellicle sales from such
     sublicense to a third party and DPI shall collect such royalty from such
     third party sublicensee and transfer such royalty to DuPont. In the case of
     photomasks and photoblanks sold hereunder, containing DuPont Material or
     using DuPont Technology in a non-pellicle application, including DuPont
     Materials sublicensed to a third party, DPI shall pay to DuPont a royalty,
     to be negotiated by the parties, which shall not be in excess of what is
     considered reasonable and customary in the micro-photolithography trade.
     DPI shall collect from such third party sublicensee such royalty and
     transfer same to DuPont.

     4.7  DPI shall have the right to prosecute infringers in the Field, upon
     written notice to DuPont of its intention to do so.  DuPont agrees to
     provide DPI with access to data and other information reasonably necessary
     for such prosecution, provided, however, that under no circumstances will
     DuPont be required to bring any legal action against an infringer, obtain a
     discontinuance of such infringement or bring suit at its own expense
     against an infringer in the Field.

     4.8  DuPont shall make decisions on when, where and whether to file future
     patent applications on inventions under subsections 4.1 and 4.3, after
     consulting with DPI, and shall share with DPI copies of any patent
     application and patent office action and permit DPI to provide its
     comments, where such application is based upon work generated under this
     Agreement.  DPI shall make decisions on when, where and whether to file
     future patent applications on inventions under subsection 4.2, after
     consulting with DuPont, and shall share with DuPont copies of any patent
     applications and patent office actions and permit DuPont to provide its
     comments, where such application is based upon work generated under this
     Agreement. Neither party shall file any patent application using the other
     party's confidential information without the prior written approval of the
     owner of the confidential information.

     4.9  In the event that DuPont elects not to have a patent application filed
     on any invention exclusively licensed to DPI hereunder in the Field or
     decides to discontinue bearing the expenses of prosecution and maintenance
     of any such application or the maintenance of any issued patent, DPI may,
     at its own expense, file, prosecute, and/or maintain any such patent
     application or patent, as the case may be.  Under these conditions
     ownership in the subject matter, as in 4.1 and 4.2, will not change.

     4.10 Should a DuPont Material be viable for use as a 157 nm pellicle, DPI
     agrees to use such DuPont Material commercially.  This obligation shall
     begin once pellicles for use in 157 nm lithography are offered for sale by
     any supplier in the global market.  After that time, in the event that DPI
     and its sub-licensees jointly achieve less than a *** share of the global
     market for 157 nm pellicles, within *** years, or if DPI decides not to use
     or to discontinue its use of DuPont Material for pellicles for any reason,
     other than supply problems from DuPont, the exclusive license to use DuPont
     Material for pellicles will cease and will become a non-exclusive, royalty
     bearing, license, at a royalty of ***, based upon the sale price, without
     the right to sublicense,  to use, import, export, sell and  offer to sell,
     any material covered by any patents hereunder for pellicles.

     4.11 DPI shall exercise commercially reasonable efforts to develop and
     sell items made using DuPont Materials within the Field, should DuPont
     materials be useful for particular end uses in the Field.

                                       3
<PAGE>

5.   TERM AND TERMINATION

     5.1  This Agreement and the research program hereunder shall continue from
     January 1, 2000 through December 31, 2001.

     5.2  Either Party may immediately terminate this Agreement by notice to the
     other Party in the event that the other Party enters into bankruptcy
     proceedings, becomes insolvent or commits an act of bankruptcy or breaches
     a material provision of this Agreement and does not cure such breach within
     thirty (30) days of notice of the breach.  However, if such breach is
     corrected within the thirty (30) day notice period, and there are no
     unreimbursed damages resulting from the breach, the agreement and licenses
     granted herein shall continue in force.

     5.3  Termination of this Agreement and the aforesaid licenses shall not
     relieve DPI or any sublicensee from the payment of any royalty or from any
     other payment obligation owed hereunder or of any obligation under the
     January 1996 Research, Development and Consulting Agreement.

     5.4  DPI and DuPont shall have the right to extend this Agreement, by
     mutual agreement, for up to two additional years, with at least two months
     prior notice before the end of the term.

6.   COSTS AND PAYMENTS

     6.1  In consideration for the services provided by DuPont hereunder,
     including the staffing as detailed in item 8, DPI shall compensate DuPont
     in the total amount of two million, four hundred and ninety two thousand
     dollars ($2,492,000.00) payable in quarterly installments beginning on
     January 1, 2000 in the amount of $311,500.00 each.  Each installment
     payment shall be due within thirty (30) days of receipt by DPI of an
     invoice from DuPont.  The first payment hereunder shall be due within
     thirty (30) days of the execution of this Agreement.

     6.2  DPI shall also make four quarterly payments of thirty-four thousand,
     five hundred ninety-six dollars ($34,596) each to total $138,384.00 to
     cover Experimental Station VUV-Vase Lease Fee, and shall make six quarterly
     payments of twenty-nine thousand, one hundred sixty-six dollars
     ($29,166.00) to cover material synthesis charges.  DuPont shall not be
     obligated to supply DuPont Material beyond these six quarters for which
     material synthesis has been funded, unless the parties agree on further
     payment for such supply.

     6.3  Any additional blanks, produced by DuPont, may be ordered by DPI at a
     cost of *** each.

     6.4  DPI agrees to pay DuPont, within thirty (30) days after execution of
     this Agreement, the sum of two hundred and fifty thousand dollars
     ($250,000.00) to pay for DPI access to DuPont prior work in the field of
     Pellicles.

7.   RELATIONSHIP TO CONSULTING AGREEMENT

     7.1  This Agreement is subject to the terms and conditions of the Research
     Development and Consulting Agreement.  To the extent there is a conflict
     between the terms of this Research Project and the terms of the Research
     Development and Consulting Agreement, the terms of this Research Project
     shall control, but only to the extent that they are applicable to the
     Research Project that is the subject matter of this Agreement.

                                       4
<PAGE>

8.   STAFFING FOR THE TERM

     8.1  DuPont shall provide for this project the equivalent of *** full time
     (FTE) scientists and *** FTE technicians.  *** are identified as key
     personnel and are part of the FTE commitment toward this program.

IN WITNESS WHEREOF, the Parties have caused this Agreement to be executed by
their duly authorized representatives.


E.I. DU PONT DE NEMOURS                 DUPONT PHOTOMASKS, INC.
AND COMPANY

By:  /s/George H. Senkler, Jr.          By:  /s/ Paul S. Chipman
     -------------------------               -----------------------------
George H. Senkler, Jr.                  Paul S. Chipman
Director-Materials Sci. & Eng.          Executive Vice President- Technology and
                                        Chief Technology Officer

Date:  April 24, 2000                   Date:  April 21, 2000
       --------------                          --------------

                                       5


                                   Exhibit A
                                   ---------
                                     * * *