ETCH-MASK OF PYROLYTIC-PHOTORESIST THIN-FILM FOR SELF-ALIGNED FABRICATION OF SMOOTH AND DEEP FACETED 3-DIMENSIONAL MICROSTRUCTURES

Etch-mask thin-film material that is particulate-free and topographica lly smooth has been created from a standard photoresist spun onto stan dard semiconductor substrates such as gallium arsenide, indium phosphi de, and silicon, and then pyrolyzed by exposing to a temperature of 30 0 degrees C in air atmosphere for 1 min on a standard laboratory hot-p late. The resulting pyrolytic-photoresist thin-him is chemically inert to many standard organic solvents including the solvent of photoresis t itself and to many inorganic reagents used in semiconductor processi ng. Therefore the pyrolytic-photoresist can be patterned by sulfur hex afluoride reactive ion etching via a standard photoresist mask. Upon s tripping the standard photoresist in a mixture of 1:1/acetone:develope r agitated ultrasonically, the remaining patterned pyrolytic-photoresi st performs as an excellent etch-mask in chemically assisted ion beam etching and reactive ion etching systems. Thus it can be a key materia l in the multilayer masking technique used to sculpt self-aligned thre e-dimensional microstructures with deep and smooth facets which are ne eded for example for photonic integrated circuits and micro-electro-me chanical systems. (C) 1996 American Vacuum Society.