Process for Generating Tapered Photoresist Edges
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
The photoresist is irradiated through a suitable mask by means of a wafer stepper. Development of the irradiated photoresist yields practically vertical edges with totally opaque structures on the mask. By using a semitransparent mask with a rather thin absorbing layer (so that part of the light is transmitted through the layer), more strongly tapered photoresist edges are produced. The edge angle can by adjusted by varying the transmission of the semitransparent areas. As shown in the figure, the area of a positive photoresist layer 14 on substrate 13 and at least some of the areas adjacent to hole 12 are exposed through a semitransparent mask 11, using a radiation at which the photoresist is almost transparent. The exposed areas are then developed by means of a basic developer.