Design And Technology Research On High G And High Sensitivity Accelerometer Based On Giant Piezoresistance Effect

An accelerometer with high acceleration range and high sensitivity based ongiant piezoresistance effect was designed and its fabrication process wasresearched. Studies on the mechanism of the giant piezoresistance were carriedout, as well as the manufacturing methods of silicon nanowires on silicon oninsullation (SOI) wafers with50nm function silicon layer. Silicon nanowires inwidth of100nm are fabricated using a conjugation of common ultravioletlithography technology and electron beam lithography technology. The structuredesign of high range accelerometer based on the developped process wasperformed, and a novel eight-beam support structure for anti-overload up to150000g is proposed. The process design is improved according to experimentalresults in real processes, and the full device fabrication steps were performed.Single step process studies such as the deep silicon wet etching, convex cornercompensation and gold-silicon bonding were carried out. The residual stressafter silicon wet etching was measured and it was found the stress decreasesunder appropriate annealing process. The piezoresistive coefficientmeasurements were performed with function structures in different lengths andwidths. The measurement results confirmed the existence of the giantpiezoresistance, and the giant piezoresistance coefficient was found in50μm*50μm*50nm piezoresistors, which can reach up to1203×10-11Pa-1,about one order higher than that of bulk silicon. The impact of residual stress onpiezoresistance coefficient after silicon dry etching was analysed as well.