Yield enhancement of piezoresistive pressure sensors for automotive applications

An approach of enhancing yield in the production of piezoresistive pressure sensors for automotive applications is described. The main idea is to introduce an advanced pre-check, which sorts out potentially bad sensors before the actual calibration. The sorting algorithm is performed in two steps. In the first step, the linear correlation coefficient for the pre-checked sensor is calculated and compared to a margin initially estimated on the basis of the production first series and continuously adjusted during the mass production in accordance with the quality management strategy. In the second step, the actual values of coefficients of the pre-checked sensor are compared with the values of the reference coefficients. Both conditions must be met to enter the evaluated sensor in the calibration procedure. Empirical data from sensor production are given to illustrate the advantage of the described approach.