A BRIDGE-TYPE PIEZORESISTIVE ACCELEROMETER USING MERGED EPITAXIAL LATERAL OVERGROWTH FOR THIN SILICON BEAM FORMATION

Merged epitaxial lateral overgrowth (MELO) of silicon has been used to form 10 mu m +/- 0.5 mu m thick, 420 mu m long, and 170 mu m wide sin gle-crystal silicon beams for a four-bridge piezoresistive acceleromet er. Buried SiO2 stripes are used to produce the near-perfect backside etch-stop for the silicon membrane, while the topside thickness contro l is established by the growth rate of 0.1 mu m min(-1). The MELO memb rane technique produces an accelerometer that has low-doped high-quali ty single-crystal silicon beams. The measured sensitivity is 287 mu V V-1 g(-1), which is about twice that for a similar device, and the non -linearity is less than 4% up to 30g of acceleration.