PIEZO RESISTANCE CHANGE SENSOR, AND MODULE, APPARATUS WITH VIBRATION DETECTING FUNCTION, PHYSICAL AMOUNT DETECTOR FOR BOILER, PHYSICAL AMOUNT DETECTOR FOR GAS AND ABNORMAL CONDITION DETECTOR

摘要

PURPOSE: To provide a piezo resistance change detecting sensor which has high sensitivity and high resolution and a wide detecting range, and moreover a using temperature limit of not lower than 150°C. ;CONSTITUTION: A sensor movable part 3 is supported to an Si substrate 1 by a beam 4. A piezoelectric resistance 5 of bark Si is formed at the front layer of the beam 4. A dielectric isolation layer 6 of air is formed between the sensor movable part 3 and the beam 4, and the Si substrate 1. A dielectric isolation layer 7 of an SiO₂ film is formed in an area of the Si substrate 1 supporting the beam 4. In order to form the dielectric isolation layer 7, a current is fed into an HF aqueous solution after a p⁺ region 11 is formed in the Si substrate 1 by ion implantation, thereby changing the p⁺ region 11 to a porous Si region 16A and a high density porous Si region 17A, and then both regions 16A, 17A are heated/oxidized to an SiO₂ region 16B and a high density SiO₂ region 17B and the SiO₂ region 16B is removed by etching.;COPYRIGHT: (C)1994,JPO