Enhancing the electric charge output in LiNbO 3 -based piezoelectric pressure sensors.

Lithium niobate (LiNbO 3 ) single crystals are a kind of ferroelectric material with a high piezoelectric coefficient and Curie temperature, which is suitable for the preparation of piezoelectric pressure sensors. However, there is little research reporting on the use of LiNbO 3 single crystals to prepare piezoelectric pressure sensors. Therefore, in this paper, LiNbO 3 was used to prepare piezoelectric pressure sensors to study the feasibility of using LiNbO 3 single crystals as a sensitive material for piezoelectric pressure sensors. In addition, chemical mechanical polishing (CMP) technology was used to prepare LiNbO 3 crystals with different thicknesses to study the influence of these LiNbO 3 crystals on the electric charge output of the sensors. The results showed that the sensitivity of a 300 μm sample (0.218 mV kPa -1 ) was about 1.23 times that of a 500 μm sample (0.160 mV kPa -1 ). Low-temperature polymer heterogeneous integration and oxygen plasma activation technologies were used to realize the heterogeneous integration of LiNbO 3 and silicon to prepare piezoelectric pressure sensors, which could significantly improve the sensitivity of the sensor by approximately 16.06 times (2.569 mV kPa -1 ) that of the original sample (0.160 mV kPa -1 ) due to an appropriate residual stress that did not shatter LiNbO 3 or silicon, thus providing a possible method for integrating piezoelectric pressure sensors and integrated circuits.