A novel poly(o-hydroxyamide) (PHA) based photosensitive polymer that exhibits high transparency at 365 nm wavelength (i-line) has been developed. Time-dependent density functional theory (TD-DFT) calculations using the B3LYP hybrid functional were performed to predict the transparencies of various hydroxyamides in the i-line region. Based on the calculations, 4,4 '-sulfonylbis(o-aminophenol) (SAP) was prepared and polymerized with 4,4 '-oxybis(benzoyl chloride) (OBBC), and the resulting PHA, which is abbreviated as PHA-S, showed a high transparency comparable to that of PHA derived from 4,4 '-(hexafluoroisopropylidene)bis(o-aminophenol). Positive-type photosensitive PHA was then formulated based on PHA-S with a crosslinker 1,3,5-tris[(2-vinyloxy)ethoxy]benzene (TVEB) and a photoacid generator (5-propylsulfonyloxyimino-5H-thiophen-2-ylidene)-2-(methylphenyl)acetoni tiile (PTMA) (17:3:1 in weight ratio), and demonstrated photosensitivity and contrast of 14 mJ/cm(2) and 2.7, respectively, when the resist film was prebaked at 120 degrees C for 5 min, irradiated by i-line, post exposure baked at 120 degrees C for 5 min, developed with an 2.38 wt% TMAH solution for 5 s. A clear positive image featuring 10-mu m line-and-space was also printed in a film which was exposed to 50 mJ/cm(2) of i-line by contact-printing. (c) 2005 Wiley Periodicals, Inc.