A photoresist that is a mixture of the esterification product of an o-quinonediazide compound and a novolak resin and a high molecular weight phenol having from 2 to 5 phenolic groups and at least 4 diazo naphthoquinone groups. The extent of esterification of the novolak resin is up to 20 percent of the hydroxyl groups and the degree of esterification of the phenol is at least 50 percent of the phenolic hydroxyl groups. The preferred novolak resins are the aromatic novolak resin that are the condensation product of a reactive phenol with a bis(hydroxymethyl)phenol or an aromatic aldehyde, each alone or in the presence of a reactive phenol.