Sub-1G MEMS accelerometer

Abstract

This paper reports a sub-1G detectable MEMS accelerometer formed by the multilayer metal intended for post-CMOS process. High density of gold enables to minimize the footprint of the proof mass without compromising the sensitivity subjected to thermal-mechanical noise. The requirements of a low-G accelerometer have been studied in terms of the fabrication process and the device structure. The Brownian noise of the accelerometer is designed to be 2.24 μg/√Hz (at RT) for a proof mass of 1020 μm × 1020 μm × 12 μm, and the estimated actual value is 5.44 μg/√Hz. Sub-1G sensing has also been demonstrated by measuring the capacitance shift as a function of the input acceleration.I.

Integrated CMOS-MEMS Technology and Its Applications

“…ii) It is applicable and scalable to various types of capacitive MEMS devices including an accelerometer in an arrayed format (13,14). iii) the calibration procedure is simple because the reference capacitor values are already known at the stage of circuit design.…”

“…Proposed CMOS-MEMS Accelerometer Figure 5 shows that an integrated CMOS-MEMS accelerometer stacked on a single LSI chip (13). In order to solve the issues on the conventional MEMS accelerometers, the proposed accelerometer needs to fulfill the following requirements; i) the accelerometer should be in an arrayed fashion to detect a broad range of acceleration by arranging the combination of several types of proof masses and mechanical suspensions, ii) the structure material for the accelerometer should be reweighed to reduce the sensor size and the mechanical noise floor, and iii) the accelerometer should be implemented on the single CMOS LSI chip to minimize the sensor footprint.…”

“…The proposed circuit also has other potentials: i) a reference capacitor in the MEMS chip is not needed, and hence the total device footprint is reduced. ii) It is applicable and scalable to various types of capacitive MEMS devices including an accelerometer in an arrayed format (13,14). iii) the calibration procedure is simple because the reference capacitor values are already known at the stage of circuit design.…”

“…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 (13)(14). We also have reported a multi-physics simulation-and-design technique to develop such CMOS-MEMS devices by using an electrical circuit simulator with a Verilog-A compatible hardware description language (HDL) for equivalent circuit description (15)(16).…”