| 摘要 |
PURPOSE: To provide a method, which etches selectively one part of a wafer consisting of a semiconductor material until a base material is formed in a desired thickness and forms a thin semiconductor wafer. CONSTITUTION: A wafer 18 is provided with a P-N junction 24, which consists of a P-type region 22 and an N-type region 20 adjacent to this region 22. Both the region 22 and the region 20 are dipped into a chemical etchant 14 and the surface of the region 22 is exposed to the etchant 14. A voltage waveform which changes in the time for a first voltage value and second voltage value is applied to the junction 24 via the etchant 14. A forward bias of 0 is generated in the front and rear of the junction 24 by the voltage waveform which changes in the time for the first voltage value, and a reverse bias is generated in the front and rear of the junction 24 by the voltage waveform which changes in the time for the second voltage value. The region 22 is removed with the etchant up to reach the region 20. Accordingly, the region 22 is roughly removed. As a result, by a current, which is generated and made to flow through the region 20, an inactive layer is formed in the surface of the region 20 and the etching of the wafer subsequent to the removal of the region 20 is stopped by this inactive layer.
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