Alkaline‐developable, chemically amplified, negative‐type photosensitive polyimide based on polyhydroxyimide, a crosslinker, and a photoacid generator

A chemically amplified photosensitive polyimide based on polyhydroxyimide (PHI) from cyclobutanetetracarboxylic dianhydride and 4,4′‐(hexafluoroisopropylidene)bis(2‐aminophenol), 4,4′‐methylenebis[2,6‐bis(hydroxymethyl)phenol] (MBHP) as a crosslinker, and (5‐propylsulfonyloxyimino‐5H‐thiophen‐2‐ylidene)‐(2‐methylphenyl)acetonitrile (PTMA) as a photoacid generator was developed to obtain the abilities of low temperature patterning, low dielectric constant, and high sensitivity. The chemically amplified photosensitive polyimide, consisting of PHI (70 wt %), MBHP (20 wt %), and PTMA (10 wt %), showed a high sensitivity (D0.5) of 5.9 mJ/cm2 and a good contrast (γ0.5) of 3.9, respectively, producing a clear negative‐tone line‐and‐space pattern with 6‐μm resolution. Furthermore, the chemically amplified photosensitive polyimide showed a high transparency in the i‐line region and a low dielectric constant of 2.54.