| 摘要 |
PURPOSE:To prevent contamination of a sensor so that the sensor adequately exhibits its function by forming a heat pattern on the rear face of a semiconductor substrate. CONSTITUTION:After the semiconductor (Si) 1 is polished to a specular surface, SiO2 films are 2, 3 are formed on both faces of the wafer. The film 3 on the rear face of the wafer is partly etched off. The Si layer is thereafter selectively etched with the remaining film 2 as a protective film. The etching is stopped upon arrival at the film 2 in the upper part of the substrate 1. A lower electrode 4 is formed by vapor deposition of metal on an SiO2/Si diaphragm formed in such a manner and further a thin piezo-electric film 5 is formed atop the same and an upper electrode 6 is deposited by evaporation atop the thin film 5. A composite piezo-electric resonator 8 is obtd. when an SiO2 7 is formed on the uppermost layer. The heat pattern 9 is formed by ion beam vapor deposi tion, etc., of platinum on the rear face of the substrate 1 and an SiO2 protective 10 is formed for the purpose of preventing deterioration on the surface thereof. The stains sticking to the substrate 1, the resonator, etc., are burned out when the pattern 9 is energized after the stop of, for example, an engine.
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