Authors: A Ravi Sankar J Grace Jency S Das
Publish Date: 2011/12/03
Volume: 18, Issue: 1, Pages: 9-23
Abstract
This paper presents design fabrication and testing of a quad beam silicon piezoresistive Zaxis accelerometer with very low crossaxis sensitivity The accelerometer device proposed in the present work consists of a thick proof mass supported by four thin beams also called as flexures that are connected to an outer supporting rim Crossaxis sensitivity in piezoresistive accelerometers is an important issue particularly for high performance applications In the present study low crossaxis sensitivity is achieved by improving the device stability by placing the four flexures in line with the proof mass edges Various modules of a finite element method based software called CoventorWare™ was used for design optimization Based on the simulation results a flexure thickness of 30 μm and a diffused resistor doping concentration of 5 × 1018 atoms/cm3 were fixed to achieve a high primeaxis sensitivity of 122 μV/Vg low crossaxis sensitivity of 27 ppm and a relatively higher bandwidth of 289 kHz The designed accelerometer was realized by a complementary metal oxide semiconductor compatible bulk micromachining process using a dual doped tetra methyl ammonium hydroxide etching solution The fabricated accelerometer devices were tested up to 13 g static acceleration using a rate table Test results of fabricated devices with 30 μm flexure thickness show an average prime axis sensitivity of 111 μV/Vg with very low crossaxis sensitivities of 0652 and 0688 μV/Vg along Xaxis and Yaxis respectivelyThe authors would like to express their gratitude to Prof S K Lahiri and Late Prof S Kal for their valuable suggestions The work was partly supported by NPSM Government of India The authors acknowledge staff members of microelectronics and MEMS laboratory IIT Kharagpur for their help at various stages in the realization of the sensors The authors acknowledge Ms Linda Mary Jacob Ms Anju and Ms Ashwini for their help in preparing the manuscript The authors acknowledge the support from ADE DRDO lab Government of India for providing measurement facilities
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