Patent ID: 7196018

Claim:
A method of etching a semiconductor substrate, the method comprising the steps of: doping a region of a substrate to yield a doped region of the substrate; applying a caustic etching paste comprising an etchant and a thickener to the doped region of the substrate, wherein the semiconductor substrate is selected from the group consisting of a microcrystalline silicon substrate, a polycrystalline silicon substrate, an amorphous silicon substrate, a doped silicon substrate, a gallium arsenide substrate, a gallium arsenide phosphide substrate, a germanium substrate, and a silicon germanium substrate, and wherein the etchant is a water-based etchant selected from the group consisting of potassium hydroxide, sodium hydroxide, ammonium hydroxide, combinations thereof, and derivatives thereof; and heating the substrate, such that the part or the layer of the substrate upon which the etching paste has been applied is etched.