Abstract
Keywords - Pressure sensor, Resistance change, Sensitivity, Piezoresistor, Bossed diaphragm
Abstract - Semiconductor sensor is made of MEMS (micro electro-mechanical system) using the micro machining technology. For instance, those sensors were classified as pressure senor, accelerator sensor, angular sensor and so on. Among those sensors, MAP (manifold absolute pressure) sensor was the first product applying the MEMS technique in the field of automobile. And also a tire pressure sensor and a fuel pressure sensor have been produced.
Especially, the tire pressure sensor improved the fuel consumption ratio and the safety in the middle of driving. Many kinds of pressure sensors have been produced as many kinds of goods according to the type of transducer.
This paper analyzed the relation between location of the piezoresistor and sensitivity of pressure sensor and variation of sensitivity with respect to width of boss, thickness of diaphragm, and deflection of diaphragm. These results are followed:
1. Resistance change of n-type <100> silicon increases about 14.7% compared with that of p-type <100> silicon in the case of rectangular diaphragm without boss.
2. According to grow the width of boss, stress and resistance change of pressure sensor decrease due to increase the stiffness of rectangular diaphragm
3. In the case of rectangular diaphragm with boss, resistance change of n-type <100> silicon decrease and that of p-type <110> silicon increase about 18.0% compared with rectangular diaphragm without boss on the condition that their deflection is same.
4. Plenty of undercutting concentrates stress to local region and resistance change region with high value reduced.