A single process for building capacitive pressure sensors and timing references with precise control of released area using lateral etch stop

In this paper, we present a capacitive absolute pressure sensor co-fabricated with a MEMS resonator using an improved epitaxial polysilicon encapsulation process. The process features insensitivity to timed hydrofluoric acid etch variation when releasing structures via sacrificial silicon dioxide. Moreover, the process enables fabrication of structures to drive/sense in both lateral (x, y) and vertical (z) directions, providing a powerful fabrication platform for sensor integration on either bulk silicon or SOI wafer substrates.