Image formation utilizing photosensitive compositions containing low metal content p-cresol oligomers

A process for producing a photosensitive element by producing a photoresist image on a substrate, which comprises:

• 1) coating a substrate with a positive working photoresist composition produced by providing an admixture of:
• (a) a photosensitive component present in an amount sufficient to uniformly photosensitize the photoresist composition comprising a diazo sulfonyl ester of p-cresol oligmers, obtained by reacting p-cresol and formaldehyde in the presence of an acid catalyst removing water and excess unreacted p-cresol, followed by adding a polar organic solvent, and filtering the solution through a 0.07 .mu.m to 0.20 .mu.m filter, said p-cresol oligomers having from about 60 mole percent to about 100 mole percent of the hydroxy groups of the p-cresol oligomer moiety esterified by one or more diazo sulfonyl chlorides, the diazo moiety ester comprises from about 60 to about 100 mole percent 2,1,4- or 2,1,5-diazo ester, or a mixture thereof;
• b) a water insoluble, aqueous alkali soluble novolak resin;
• the novolak resin being present in the photoresist composition in an amount sufficient to form a substantially uniform photoresist composition;
• and
• c) a suitable photoresist solvent;
• 2) heat treating the coated substrate until substantially all of the solvent is removed;
• 3) image-wise exposing said photoresist composition;
• and
• 4) removing the image-wise exposed areas of said photoresist composition with a suitable developer.