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.