A new positive working, aqueous base developable photosensitive polybenzoxazole (PBO) precursor composition based on a partially tetrahydropyranyl (THP) protected PBO precursor and a Bisphenol A based 1,2-naphthoquinone diazide-4-sulfonate (DNQ-4) photosensitive compound has been developed. The polymer was prepared from a low temperature polymerization of 2, 2'-bis-(3-amino-4-hydroxyphenyl) hexafluoropropane (BisAPAF) and isophthaloyl chloride (IC), followed by reacting with 3,4-Dihydro-2H-pyran in the presence of p-toluenesulfonic acid monohydrate as a catalyst. The photosensitive PBO precursor containing 20wt % DNQ-4 photosensitive compound showed a sensitivity of 221 mJ/cm(2) and a contrast of 1.44 in a 3 mum film with a 0.6wt % tetramethylammonium hydroxide (TMAH) developer. A pattern with a resolution of 10 pm was obtained from this composition. The novel PBO precursor photosensitive composition showed a significant improvement in dark film loss after development, which can and could be used to make a thick film resist.