| 摘要 |
PURPOSE:To form an etching stop layer which does not almost affect an adverse influence to the characteristics of a semiconductor device by dividing a semiconductor layer having small first etching velocity into at least two or more layers. CONSTITUTION:A semiconductor layer 14 is grown on a high resistance substrate 15, and a high purity semiconductor layer 11 having a small evaporation rate is then grown. Here, the layer 11 which becomes a thermal etching stop layer is divided, for example, into 3 layers, and high purity semiconductor layers 13 having a larger evaporation rate than that of the layer 11 are grown therebetween. Then, a high purity semiconductor layer 12 having a large evaporation rate is grown. Since the layer 11 having a small evaporation rate is thus used, an etching depth can be automatically decided to form a field effect transistor which has small short channel effect and small source resistance.
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