Method of selectively etching semiconductor material.

摘要

The present invention relates to a method of forming thin bodies of a semiconductor material, such as single crystalline silicon, by selectively etching away a portion of the body until a body of the desired thickness is obtained. The body (18) includes a p-n junction (24) made up of adjacent regions of p-type (22) and n-type (20) conductivity which are immersed in a chemical etchant (14) with the surface (22a) of the p-type region being exposed to the etchant. A time varying voltage waveform having first and second voltage levels is applied through the etchant to the p-n junction. The first voltage level causes a zero forward bias across the p-n junction and the second voltage level causes a reverse bias across the p-n junction. The p-type region is removed by the chemical etchant down to the n-type region. This essentially removes the p-n junction in the area where the p-type region is etched away and resulting current through the n-type region causes a passivating layer (32) to form on the surface of the n-type region which stops further etching.