Vacuum gauging with complementary metal–oxide–semiconductor microsensors

We report different types of vacuum microsensors (size <500 μm). The devices were fabricated with a standard complementary metal–oxide–semiconductor integrated circuit process followed by silicon bulk micromachining or surface micromachining. Two sensors are thermal, and a third type is resonant. Their pressure response results from the pressure dependent dissipation of energy or momentum to the surrounding gas. Different designs with sensitive ranges from 1 to 106 Pa are demonstrated. The sensor responses are modeled using kinetic gas theory, with the conclusion that a typical dissipation length defined by the device geometry determines the useful pressure range.