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Mixed Resin Photoresist System for Mid and Deep Ultraviolet

IP.com Disclosure Number: IPCOM000045064D
Original Publication Date: 1983-Jan-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Bushnell, LP: AUTHOR [+3]

Abstract

Conventional diazonapthoquinone ("DQ") sensitizer containing photo-resists contain a casting solvent, a novolak resin (typically based upon a cresol, phenol or cresylic acid), and a photoactive compound (PAC) which is photolyzed from a hydrophobic R (DQ)(n) form to a carboxylic acid form (R(X-COOH)(n)), which is then soluble in an aqueous base. It has been found that a mixture of several novolak resins, rather than a single resin, provides an improved performance. In particular, a high molecular weight novolak resin based upon a cresylic acid (such as VARCUM (Trademark of Reichhold Chemicals Inc.) 6000-x series resins, number average molecular weight approx.

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Mixed Resin Photoresist System for Mid and Deep Ultraviolet

Conventional diazonapthoquinone ("DQ") sensitizer containing photo-resists contain a casting solvent, a novolak resin (typically based upon a cresol, phenol or cresylic acid), and a photoactive compound (PAC) which is photolyzed from a hydrophobic R (DQ)(n) form to a carboxylic acid form (R(X-COOH)(n)), which is then soluble in an aqueous base. It has been found that a mixture of several novolak resins, rather than a single resin, provides an improved performance. In particular, a high molecular weight novolak resin based upon a cresylic acid (such as VARCUM (Trademark of Reichhold Chemicals Inc.) 6000-x series resins, number average molecular weight approx. 900, weight average molecular weight=8000) when combined with an orthocresol based novolak resin (or other substituted phenol-based novolak resins of significant aqueous base solubility),, such as Ciba Geigy HT9490 or Schenectady Chemical Co. HRJ-927, (which have molecular wt.8n)=910, molecular wt.(w) approx.=2000) give improved performance.

The origin of the improved performance is believed due to a high concentration of PAC in the top of the film and/or high molecular weight segregation in the top layer of the film and/or serious depletion of residual casting solvent in the top region of the film. This top region of the film is of the order of
0.15+/-.1 Mum thick. This region is formed during solvent evaporation, during spin coating and/or a pre-exposure baking step, under conditions of 70-100 degrees C for 15-30 minutes. The resistance this region to dilute...