A Silicon Resonant Type Ceramic Pressure Sensor with Minimal Effect of Ambient Temperature

Abstract

This paper proposes a silicon resonant type ceramic pressure sensor with a minimal effect of ambient temperature. A static force driven silicon resonant sensor chip, which enables high accuracy, excellent repeatability, and long-term stability, is directly bonded on a silicon nitride (Si₃N₄) diaphragm by surface activated bonding. To minimize the thermal strain induced by the difference of coefficient of thermal expansion between silicon and Si₃N₄, a temperature compensation was achieved by designing a round-shape bonding area on the chip and by tuning thickness ratio of the chip and the diaphragm. As a result, it is confirmed that the thermal strain of the silicon resonator (-0.013 µε/°C) was much smaller than the pressure strain (46 µε/MPa), which corresponds to simulation results.