Browse Prior Art Database

Protection of Photomasks With PNO Films

IP.com Disclosure Number: IPCOM000059678D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Hsia, LC: AUTHOR [+2]

Abstract

Phosphorus-nitrogen-oxygen (PNO) films, which are easily deposited, chemically inert to most solvents, and abrasion resistant, are used to protect masks used in photolithography. Photomasks used in the manufacture of semiconductor integrated circuits are typically fabricated by forming a patterned metal layer on an insulating substrate, for example, chromium on quartz. The masks undergo numerous etching, stripping and cleaning steps during which they are subjected to chemicals that can cause defects in the mask pattern. These mask defects reduce the yield and reliability of subsequently fabricated integrated circuit devices. These defects can be reduced and the wear resistance of the mask increased by forming a first PNO film over the insulating mask substrate prior to formation of the metal layer.

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Protection of Photomasks With PNO Films

Phosphorus-nitrogen-oxygen (PNO) films, which are easily deposited, chemically inert to most solvents, and abrasion resistant, are used to protect masks used in photolithography. Photomasks used in the manufacture of semiconductor integrated circuits are typically fabricated by forming a patterned metal layer on an insulating substrate, for example, chromium on quartz. The masks undergo numerous etching, stripping and cleaning steps during which they are subjected to chemicals that can cause defects in the mask pattern. These mask defects reduce the yield and reliability of subsequently fabricated integrated circuit devices. These defects can be reduced and the wear resistance of the mask increased by forming a first PNO film over the insulating mask substrate prior to formation of the metal layer. After the metal layer is patterned, a second PNO film is formed thereover, thus eliminating the metal-to-insulating layer interface and encasing the metal layer in a protective coating. The PNO films can be prepared as described in U.S. Patent 4,172,158 by chemical vapor deposition in the temperature range of 400OE to 900OEC, or by a plasma- enhanced chemical vapor deposition process at temperatures below 400OEC. PNO film thicknesses of about 2000 to 3000 Angstroms are sufficient to protect the photomask.

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