A temperature compensated dual beam pressure sensor

The first temperature compensated leverage beam pressure sensor fabricated by surface micromachining is presented. The pressure- sensing element consists of a piezoresistor on an 80 mum x 40 mum x 1 mum double end supported force transducing beam. The beam is located beneath a (100 mum x 100 mum x 2 mum) square polysilicon diaphragm having its ends attached to the diaphragm and to the cavity edge, thus, entirely enclosed inside the vacuum cavity. The thermal compensation piezoresistor is also located in the cavity on a (100 mum x 40 mum x 1 mum beam to achieve nearly identical thermal conditions. Both ends of this beam are attached to the cavity edge and is therefore, pressure-insensitive. The new design enables a combination of high pressure sensitivity (0.8 muV/(V mmHg)), environmental isolation and a decrease of the relative temperature dependency mismatch from 6 to 3% compared to a commercialized traditional piezoresistive pressure sensor. (C) 2002 Elsevier Science B.V. All rights reserved.