CMOS-MEMS -new frontier of multilevel interconnect technology

Summary form only given. This paper reports a feature and techniques of CMOS-MEMS technology. Fusion of microelectromechanical systems (MEMS) with CMOS LSI technologies is a promising way to establish high functional devices. We have been developing CMOS-MEMS technology that fabricates MEMS devices on CMOS LSI (1-2). The CMOS-MEMS technology that advances the multilevel interconnection technology has the feature of high-functionality, high-accuracy, and mass-production. We focused on the MEMS accelerometer as the application of CMOS-MEMS technology. Various types of MEMS accelerometers have been used in a wide variety of application fields such as mobile devices, air bag ignition for vehicles, and vital-sign monitoring systems(3-5). Moreover, commercially available inertial sensors deal mostly with more than 1 G (1 G = 9.8 m/s2: gravitational acceleration). There is an increasing demand for the accurate sensing of acceleration below 1-G, as we call sub-1G range. Thus, sub-1G sensing, small device footprint, and low power consumption are required. Nonetheless, difficulty still remains, because the large dimensions of the proof mass tend to increase the device area and the accelerometer chip is usually made to be separate from the LSI chip, thereby requiring a system in package (SiP) assembly. In order to solve these problems, we have proposed an integrated CMOS-MEMS accelerometer made of electroplated gold that is integrated onto the sensor LSI chip(6-9). In conclusion, it is confirmed that CMOS-MEMS technology will shed light on a solution of new technical trends.