Calibration Improvement for Piezoresistive Coefficients of Stress Sensors on (100) Silicon

Abstract

Ever since the 1980s, the resistor sensors for stress measurement in plastic encapsulated electronic packages of IC have been studied. Nowadays, many well-developed designs and applications of stress sensors have been realized. Calibrations of those stress sensors for accurately evaluating their piezoresistive coefficients, however, have not developed so fast. Among those calibration methods, the four-point-bending (4PB) method, which has been used since the 1980s, is still the most popular one. In the first part of this paper the advantages and disadvantages of three kinds of calibration methods are introduced and compared. The theories on the popular 4PB method are presented in the second part. For better use of the 4PB method during calibration, some improvement on the basis of traditional 4PB fixture is made. In the third part, the analysis of how the improvement works is described in details and a comparison between the improved 4PB fixture and the traditional one is also presented.