Patent ID: 7235348
Filing Date: 2007-06-26
Classification: G03F

Abstract:
1. A method of applying a water soluble negative-tone photoresist for creating closely spaced contact holes, comprising the steps of: providing a substrate, said substrate having been provided with a first layer of photoresist for creation of a pattern of contact holes; exposing the surface of said first layer of photoresist with a first mask, said first mask comprising a first and a second pattern of contact holes; creating openings in said first layer of photoresist in accordance with said first and second pattern of contact holes; depositing a second layer of negative-tone photoresist over the surface of said first layer of photoresist, including said openings created in said first layer of photoresist, wherein the second layer of negative-tone photoresist comprising a water soluble negative photoresist contains no solvent that damages the first layer of photoresist; and creating openings in said second layer of negative-tone photoresist in accordance with said second pattern of contact holes, wherein the water soluble negative photoresist comprises a base polymer, a cross linking element, photo-active compound, a quencher and a solvent, and the base polymer comprises between about 4 to 8% of polyvinylacetal as component of the negative-tone photoresist.