| 摘要 |
PURPOSE:To form P- and N-type silicon islands having substantially identical thicknesses with high precision, by providing a silicon island of a second conductivity type on an exposed surface of a silicon substrate of a first conductivity type and selectively polishing the structure. CONSTITUTION:An N-type silicon substrate 1 of plane orientation 100 is first provided with an N-type silicon island 2 and a P-type polycrystalline silicon 4 overlaid on the island 2 with an oxide film 3 interposed therebetween. Further, a P-type silicon island 6 and a transition region 5 are formed on the exposed surface of the substrate. The P-type silicon island 6 is selectively polished until it is as thick as the N-type silicon island 2. After the top face of the P-type silicon island 6 is covered with a silicon oxide film 3A, the transition region 5 and the P-type polycrystalline silicon layer 4 are removed with an alkali solution. The N-type silicon island 2 and the P-type silicon island 6 are covered with a silicon oxide film 3B and a polycrystalline silicon layer 7 is deposited thereon. The silicon layer 7 is then polished to the level of A-A', and from this reference, the silicon layer is polished down to the level of B-B' by means of the selective polishing process. In this manner, the silicon islands of the first and second conductivity types with substantially identical thicknesses can be formed with high precision.
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