A Finite Element Method Based Approach of Modeling of a Piezoresistive Accelerometer by Incorporating Doping Profile of a Diffused Resistor

Abstract

Finite element analysis (FEA) is an efficient method to observe the behavior of a sensor and to optimize the design to achieve high performance. In the modeling of piezoresistive sensors, typical FEA techniques simplify the doping concentration as a constant profile throughout the junction depth of a piezoresistor. This approximation overestimates or underestimates the performance of the modeled device from the actual fabricated device. In this paper, a two-step modeling of piezoresistive sensors by incorporating nonuniformly doped piezoresistor is presented using TCAD TSUPREM4® and IntelliSuite® tools to achieve lower deviation between simulation and experimental results. The two-step modeling technique illustrates the method of choosing the number of slices and the slicing strategy to effectively model the uniform doping profile of a piezoresistor. A quad-beam proof-mass aligned piezoresistive accelerometer is considered for the validation of the modeling method by comparing the simulated results with the fabrication results. From the results, it is observed that the proposed adaptive slicing method with more slices at the surface of the piezoresistor provides the least deviation error of 5.43 %.