The investigation of the characteristic and application of the porous silicon layer

• Main Authors: Gee-Wen Chou, 周基淵
• Other Authors: Chung-Cheng Chang
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/72447409477321434059

碩士 === 國立海洋大學 === 電子工程學系 === 82 === The objects of this paper focus on the fabrication and characterization of high sensitive silicon pressure sensors for measurement of gas pressure. Although the mechanic type pressure sensors have been used widely, the silicon pressure sensors have excellent characteristics, such as small size, high sensitivity and the possibility of monolithic integration of electronic devices, which may be used more attractively in the future. In semiconductors, the numbers of charge carriers are expected to change by applied stress, which causes the energy gap change between the valence and conduction band. Therefore, the resistivity would change. This is one of the best features for silicon pressure sensors utilizing piezo- resistance effect for measuring very low pressure. Silicon pressure sensors consist of a thin square diaphragm as an elastic material and four piezoresistive guage resistors which are made by diffusing impurities into the　diaphragm surface. When pressure is applied to the diaphragm, the guage resistance will change due to the piezoresistance effect. In this experiement, the parameters which may influence the characteristics of sensors including the diaphragm thickness, piezoresistors layout, dopant concentration, junction depth and environmental temperature etc. are discussed From the results of this experiment, it can be found that on (100) n type Si substrate, with the diaphragm is thinner and the junction depth is shallower, one would obtain the highest sensitivity as the piezoresistors are along the [110] direction.