Controlling Dissolution Rate of Novolac Resins in Positive Photoresists
Original Publication Date: 1985-Jan-01
Included in the Prior Art Database: 2005-Feb-18
This method controls the dissolution rate of novolac resins in photoresists by modifying the hydroxyl groups into more acidic carboxylic-acid groups, by esterification with acid anhydrides. The amount of modification can be adjusted to obtain the desired resin speed. Controlling the synthesis of phenolic resins (e.g., novolac and polyvinyl phenol resins) is difficult. The molecular weight distribution in polymers can vary broadly, causing the dissolution rate of resins to vary. If the resin speed (the dissolution rate of resins in aqueous base solutions) is out-of-specifications, the synthesized resin becomes useless. The previous method covered only ways to slow down resin speed. This method increases the resin speed of slow resins. Succinic anhydride is added to phenolic resin solution.