New photoresist coating method for 3-D structured wafers

This paper presents a method for the uniform coating with standard photoresist of a [100] semiconductor wafer containing anisotropically wet-etched through-holes. The coating method is based on photoresist dispensing on the mask opening side of the wafer and spinning the wafer from both sides in saturated photoresist solvent atmosphere. Special attention is paid to the improvement of photoresist coverage of the obtuse holes' corners by rounding them first in TMAH solution. The method offers the possibility for realisation of different structures in wafer through-holes. Moreover, it could also be applied for spinning photoresist in grooves with very good uniformity, which requires minimal changes in the standard coating equipment. The method is simple, fast and low-cost in comparison with other photoresist coating techniques. (C) 2000 Elsevier Science S.A. All rights reserved.