Micro silicon multi-function integrated sensor

This paper presents a monolithically integrated multi-function sensor in low volume. The integrated sensor includes pressure, temperature and humidity sensor. They are based on the principle of silicon piezoresistive effect, mobility change, and variable capacitance respectively. The chip is started with n-type (100) silicon, and both bulk micromachining and surface micromachining are used to fabricate the device. The piezoresistors are obtained by Boron ion implantation. To diminish the effect among each other, the temperature resistor is located along [100] direction while pressure gauge resistors are along [110] direction. Temperature output can realize the precise compensation for the temperature offset of the pressure output of the sensor. The whole chip is 5 mm× 5 mm. The integrated sensor has good sensitivity, linearity and low hysteresis.