JPS6432175A - Semiconductor acceleration sensor - Google Patents

Abstract

PURPOSE:To obtain a low-cost sensor which enables the thickness of an epitaxial layer to be set freely by using a single crystal substrate having no epitaxial layer and controlling the thickness of a beam by giving a stage to the oxide film of an etching mask. CONSTITUTION:An n-type silicon substrate 1 having no epitaxial layer is oxidized thermally to cover the surface with an oxide film 2. Then this oxide film 2 is bored and p-type impurities are implanted in the holed part to form a gauge resistance diffusion layer 3. Then while a diffusion gauge is contacted by Al wiring 4, an nitride film 5 is formed as a final protection film by plasma CVD. Here, a through-hole 8 around the weight part of the etching mask on the reverse surface is etched with an etching liquid whose etching rate is slow, the beam part 9 and through hole 8 are patterned with photosensitive resin, and then etching is performed from on the oxide film. In this case, the thickness of the beam is controlled by giving a stage to the oxide film of the etching mask by using a prescribed expression, so when the oxide film of the beam part 9 is etched, the difference in etching depth between the through part 8 and beam part 9 is equal to the thickness of the beam part which is left finally.