Positive-photosensitive polyimide based

We report on the positive alkali-developable photosensitive polyimides based on an alkali-soluble polyimide precursor as a base polymer and diazonaphthoquinone (DNQ) sensitizer to improve process stability and sensitivity. Polyamic acid ester with pendant carboxylic acid (PAE-COOH) showed good dissolution behavior in aqueous alkali developer. The dissolution rate of PAE-COOH was controlled by the content of pendant carboxylic acid. It was found that a photosensitive system composed of butyl ester of PAE-COOH and a DNQ compound can avoid the residue at the edge of hole patterns (footing) after development, while that of methyl ester of PAE-COOH showed the residue. A DNQ compound containing sulfonamide derived from diaminodiphenylether renders improved sensitivity compared with DNQ compounds derived from phenol derivatives. 

C = covalent-type photosensitive polyimide precursor IN = ionic-type photosensitive polyinhde precursor N = negative image tone P = positive image tone G = sensitive to g-line (436 nm) of Hg lamp H = sensitive to h-line (406 nm) of Hg lamp I = sensitive to i-line (365 nm) of Hg lamp BB = sensitive to unfiltered output of Hg lamp S = developed using solvent mixtiues and A = developed using aqueous bases. 

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