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Multilevel Chromium Mask Repair Process for Clear Defects

IP.com Disclosure Number: IPCOM000061685D
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Sargent, RJ: AUTHOR

Abstract

Blanket chromium (Cr) films on transparent substrates intended for use as photomasks frequently have clear defects (regions where no Cr or thin Cr exists). A process is described for repairing these defects. The figure shows a transparent substrate 2 having a Cr film overlayer 4. Note the clear defect region d, (i.e., a region initially devoid of Cr). An organic layer 6 is deposited on the Cr layer 4, and is overlayed with a continuous film 8 of an inorganic material. Next, positive photoresist (not shown) is applied on the organic film 8. The positive photoresist is then exposed by light passing upward through the transparent substrate 2, the clear defect d, and the transparent film layers 6 and 8.

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Multilevel Chromium Mask Repair Process for Clear Defects

Blanket chromium (Cr) films on transparent substrates intended for use as photomasks frequently have clear defects (regions where no Cr or thin Cr exists). A process is described for repairing these defects. The figure shows a transparent substrate 2 having a Cr film overlayer 4. Note the clear defect region d, (i.e., a region initially devoid of Cr). An organic layer 6 is deposited on the Cr layer 4, and is overlayed with a continuous film 8 of an inorganic material. Next, positive photoresist (not shown) is applied on the organic film 8. The positive photoresist is then exposed by light passing upward through the transparent substrate 2, the clear defect d, and the transparent film layers 6 and 8. Following photoresist development, a reactive ion etch (RIE) is used to form a vertical walled hole through film layers 6 and 8 over the clear defect d. The photoresist is removed during the RIE process. A second Cr film 10 is deposited by vacuum or sputter deposition. The Cr film 10 fills the defect region d initially existing in Cr film 4. Thus a totally opaque (i.e., defect-free) Cr film 4 is left on the transparent substrate 2 after layers 6 and 8 plus the Cr film 10 on top of film layer 8 are stripped away by etch and lift-off processing. Patterned photomasks which are found to have clear defects after processing may be similarly repaired using a small, directed light beam to ensure exposure of the photore...