A tri-axis MEMS capacitive sensor using multi-layered high-density metal for an integrated CMOS-MEMS accelerometer

This paper reports a novel tri-axis microelectro-mechanical systems (MEMS) capacitive sensor utilizing multi-layer electroplated gold. The high density of gold has enabled us to minimize the Brownian noise and hence to reduce the footprint of the proof mass. To optimize the flexibility of the mechanical springs for tri-axis motions, we have newly developed multi-layered metal spring structures. All the MEMS structures have been made by gold electroplating, used as a post complementary metal-oxide semiconductor (CMOS) process, and thereby the MEMS sensors can be implemented as integrated CMOS-MEMS accelerometers.