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Thermally Stable Positive Diazoquinone Resists

IP.com Disclosure Number: IPCOM000049143D
Original Publication Date: 1982-May-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 178K

Publishing Venue

IBM

Related People

Fredericks, EC: AUTHOR [+3]

Abstract

AZ-1350, Hunt-204 and Polychrome 129 are examples of positive resists composed of novolak resin with a diazoquinone sensitizer. These formulations are melt resistant to 150 degrees C treatments. With plasma they have an extended melt stability to 200-250 degrees C range. Such a process, however, requires extra steps with precise equipment. Previous attempts to formulate the diazoquinone resists with other polymers, such as resole type phenolic resins, have not been successful due to crosslinking of the resist formulation even at low prebake less than 95 degrees C.

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Thermally Stable Positive Diazoquinone Resists

AZ-1350, Hunt-204 and Polychrome 129 are examples of positive resists composed of novolak resin with a diazoquinone sensitizer. These formulations are melt resistant to 150 degrees C treatments. With plasma they have an extended melt stability to 200-250 degrees C range. Such a process, however, requires extra steps with precise equipment. Previous attempts to formulate the diazoquinone resists with other polymers, such as resole type phenolic resins, have not been successful due to crosslinking of the resist formulation even at low prebake less than 95 degrees C.

It has been found that thermoset performance and hence high thermal stability can be incorporated into these resists by the addition of phenolic dimethoyl trimers in an amount of from 3 to 20 percent by weight of the resists. The modified resist is processed under the usual conditions (85 degrees C prebake). Postbake of the resist at greater than 200 degrees C thermosets the resin without flow.

The dimethoyl additives consist of a given general formula (see original).

The methoyl phenolics are synthesized by stepwise condensation of P-cresol and formaldehyde, according to M. Koebner, Angewandte Chemie 46, 251 (1933).

The high temperature stability of the modified resist is applicable to new improved lithographic processes: Reactive Ion Etching. The etching of Al-Cu with chlorine

gases requires greater than 250 degrees C temperatures to

prevent product redep...