| 摘要 |
PURPOSE:To obtain a dielectric isolation substrate wherein bending is little and there is no increase of electrostatic capacitance, by arranging a first polycrystalline semiconductor containing additive on a dielectric film, arranging thereon a second polycrystalline semiconductor containing no additive, and arranging thereon a third polycrystalline semiconductor containing no additive. CONSTITUTION:On a main surface of a single crystal semiconductor 1 having a trench on the main surface, a dielectric film 2 is formed, on which a polycrystalline semiconductor is formed by vapor growth. Then, in the neighboring part with the dielectric film 2, a first polycrystalline semiconductor 31 containing additive is arranged, on which a second polycrystalline semiconductor 32 containing no additive is arranged so as to fill the trench, and thereon, a third polycrystalline semiconductor 33 containing additive is arranged. In this process, sintering occurs in the semiconductor 32, and silicon particles neighboring with each other fuse and form lumped silicon particles. Thereby, a dielectric isolation substrate can be obtained wherein bending is little and there is no increase of electrostatic capacitance.
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