Research for piezoresistive pressure sensors: Methods to reduce the influence of processing deviation on sensitivity and improve product consistency

Much has been done in improving the performance of piezoresistive pressure sensors in various aspects. It is also important to realize good consistency among different device units on a big wafer under the circumstance that the manufacture of piezoresistive pressure sensors is highly industrialized. Bad product consistency results from processing deviation which is hard to control and can never be reduced to zero. An effective approach to reduce the influence of processing deviation on sensitivity of pressure sensors is provided in this paper: properly enlarging the size of the square silicon diaphragm. Finite element analysis (FEA) is basically used in the work. Test results show that relative errors for sensitivity of pressure sensors with diaphragm of larger size(length of 300um) are limited within 2.2% while pressure sensors with diaphragm of smaller size(length of 200um) from the same wafer have relative errors for sensitivity varying a lot, from 0.1% to 32.2%.