| 摘要 |
PURPOSE:To ensure enable etching for a very small place on the surface of a p-layer by a method wherein a silicon wafer equipped with a p-n junction is placed in an alkaline liquid and a pulsating voltage is repeatedly applied across the p-layer and n-layer of the silicon wafer or across the silicon wafer and the alkaline liquid. CONSTITUTION:A pulsating voltage source 10 applies a pulsating voltage to a silicon wafer 3. The silicon wafer 3 is constituted of a p-layer 3a and an n-layer 12 covering the p-layer 3a with very small portions 11a, 11b left exposed. When the pulsating voltage source 10 applies a voltage of 5V pulsating at 0.04Hz to the n-layer 12, the entry/exit of ions is obstructed to lower the etching rate, because a barrier emerges in the small portions 11a, 11b belonging to the p-layer 3a when the n-layer 12 is exposed to a voltage of 5V. When the voltage is zero at the n-layer 12, there exists no barrier and the entry/exit of ions is freely made, which allows the very small portions 11a, 11b to be effectively affected by etching.
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