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US 4,173,470 AGranted
Novolak photoresist composition and preparation thereof
AssigneeBell Telephone Laboratories, Incorporated
InventorsSusan Fahrenholtz, David T. Long, Raymond C. Pitetti
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Abstract
A novolak resin suitable for use as a light-sensitive photoresist or maskant is prepared by reaction of at least one cresol with an aldehyde or reactive ketone and an aromatic hydroxyl compound having an alkyl side chain of from 3-15 carbon atoms. The addition of a conventional photosensitive agent yields a composition evidencing superior characteristics as compared with prior art novolak photoresists and which requires less sensitizer than such prior art resists.
Claims8
Method for the preparation of a positive photoresist which comprises the steps of
- (a) reacting at least one cresol with a condensation agent selected from the group consisting of aldehydes and reactive ketones, said condensation agent having less than 10 carbon atoms and at least one carbonyl group per molecule, and a hydroxylated aromatic of the general formula ##STR2## wherein R is an alkyl group having from 3-15 carbon atoms, said reaction being effected in the presence of a condensation catalyst,
- (b) heating the reaction mixture to reflux over a time period ranging from 12 to 24 hours,
- (c) subjecting the resultant mixture to vacuum distillation at a temperature ranging from 200-300 degrees C., and
- (d) adding a photosensitizing agent and a solvent to the resultant product.
1 more element
Dependencies are inferred from the claim text.