This paper describes a simple method to identify the membrane thickness of the piezoresistive pressure sensor by the so-called “slotarray” which has been made in advance on the wafers before sensor fabrication. Such a method can be applied as a substitute for other etch-stop techniques with micrometer-resolution. The results can also be used to check the uniformity of pressure sensors and give a guideline for further improvements in the batch process of silicon bulk micromachining. A series of pressure sensors with a chip size of 3×3×0.2mm3 were presented as the examples of the V-groove slot-array method. The finite element method (FEM) software ANSYS was accessed to predict the stress and resistance change of the sensors. The new pressure sensors with stiffened-bosses are tested and had a best sensitivity of 9.0 mV/atm/V and a non-linearity less than 1%.
Journal of the Chinese Institute of Engineers=中國工程學刊 20(3), pp.335-347