Novel Sensor Structure and Its Evaluation for Integrated Complementary Metal Oxide Semiconductor Microelectromechanical Systems Accelerometer

This paper reports a novel sensor structure and its evaluation results for an integrated complementary metal oxide semiconductor (CMOS) microelectromechanical systems (MEMS) accelerometer with a wide detection range on a chip. The proposed sensor structure has the following features: i) a layer separation technique between the proof mass and the mechanical suspensions, ii) mechanical stoppers for the proof mass to avoid destruction, and iii) a SiO2 film underneath the proof mass to prevent stiction and electrical short. Gold was used as the MEMS structure material to reduce the proof mass size and to lower the Brownian noise to below 100 mu g/root Hz. Furthermore, the micro fabrication was carried out below 310 degrees C for the CMOS devices to remain intact. The evaluation results indicate that the Brownian noise was 90.6 mu g/root Hz. Thus, we have confirmed that the proposed MEMS structure has the potential for use in future integrated CMOS-MEMS accelerometers. (C) 2013 The Japan Society of Applied Physics