photo resist image layers , particularly those used for high resolution geometries in microelectronic applications , are stabilized against distortion or degradation by the heat generated during subsequent etching , ion implantation processes and the like , by the application of a film of a thermally stabilizing agent prior to post - development bake of the image layer . high temperature resistant film forming polymers , of which gelatin and gelatin hydrolysates are preferred examples , are employed as thermally stabilizing agents . the process serves to achieve thermal stabilization of the photoresist image layer without significantly affecting the ease of subsequent stripping of the layer . it is particularly effective when used to thermally stabilize positive resist images derived from photoresist systems based on novolak resins .