| 摘要 |
PROBLEM TO BE SOLVED: To provide a gas sensor of long life by providing a detecting part having an oxidation catalyst layer of thickness in specific dimensional range on a substrate diaphragm part. SOLUTION: A silicon substrate 1 is thermally oxidized to generate a silicon oxide layer 2 on the surface, and a silicon nitrate layer 3 is generated thereon by a CVD method. The terminal 4a of a platinum heater 4 and a heater part 4b are sputtered thereon, and the heater part 4 is coated with an oxidation catalyst layer 5 of thickness of about 20μm by screen printing. For the oxidation catalyst, palladium, rhodium, platinum, or the like is used, for the support, alumina, silica, titanium oxide, or the like is used, and the catalyst addition quantity is bout 5-15 wt.%. The back of the silicon substrate 1 in the vicinity of a detecting partαprovided with the oxidation catalyst layer 5 is removed by anisotropic etching, and the silicon oxide layer 2 is exposed to form a diaphragm partβ. Hence the heat capacity and thermal conductivity of the detecting partαare reduced, and the sensitivity is improved and the life is prolonged. Further, the thickness of the oxidation catalyst layer 5 is set to be under about 300μm, and power consumption is reduced to dispense with exchange of a battery.
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