To extend the pressure capability t

To extend the pressure capability to very low-pressure readings (≤2 inches, or 5 cm, of water) and minimize nonlinearity, several different approaches are being pursued. Those approaches include silicon bosses used as stress concentrators in circular, square, and dual rectangular diaphragms; convoluted square diaphragm; and etch stop techniques to control the diaphragm thickness. Diaphragms as thin as 2.5 mm have been used to produce capacitive pressure sensors for 300 mtorr and lower pressure applications [10].Micromachining can be enhanced by using the electronics capability inherent from semiconductor manufacturing. That may provide an additional solution for low-pressure measurements.