PHOTOLITHOGRAPHIC PATTERNING OF POROUS SILICON USING SILICON-NITRIDE AND SILICON-CARBIDE MASKS

In this study, a two-step photolithographic process for selective form ation of porous silicon is described. The process utilizes coatings of silicon nitride or silicon carbide on silicon. These films are imperv ious to the HF solution during anodic etching in an ambient environmen t. However, when the coated wafer is illuminated during anodization, m icrocracks are produced in the illuminated regions. Creation of these microcracks results in formation of porous silicon in the underlying r egions. The patterning of 100 mu m features is deemed possible with th is technology.