| 摘要 |
PURPOSE:To obtain the device with high reliability which is hard to be subjected to the chemical action of measuring gas without the degradation in sensitivity and the delay in response by coating the surface of a diaphragm, its support, metal electrodes and lead wires with Si3N4, TiO2, or Ta2O5. CONSTITUTION:The diaphragm 2, the support 3, a strain gage 4, an impurity diffused layer 5, and the metal electrode 7 are formed by the conventional method, and the lead 12 is connected to the electrodes 7 and 11. Then, the strain gage 4 and the diaphragm 2 are coated with SiO2 6, and the surface of the support 3, the electrode 7, and the lead 12 are coated with Si3N4 by the CVD method, or with TiO2 or Ta2O3 by the reaction sputtering method. Since a pressure sensing element 1 and a mounting table 8 can be kept at a relatively low temperature and an insulating film 13 can be formed, the effects are not applied to the bonding agent 9 between the sensing element 1 and the table 8, and the bonding part between the electrodes 7 and 11 and the lead 12. Since the insulating film 13 is fixed to the diaphragm 2 together with SiO2 6, the film 13 is bent with the diaphragm as one body. Therefore the delay in the response speed can be disregarded, and the surface of the diaphragm can be protected from the chemical action of the gas. |
