Design And Fabrication Of A Low Pressure Mems Capacitive Sensor

The purpose of researching low pressure sensors is tackling pressure measurement problems at low-pressure environments. A low pressure MEMS capacitive sensor has been proposed aimed at the problem of sensitivity decline in narrow pressure range. According to the advantages in low pressure measurement of capacitive sensors, capacitive structure based on space-adjustable parallel-plate capacitor has been adopted to measure low pressure.Nowadays, there is a tendency to use surface micromachining process fabricating MEMS devices for the purpose of miniaturization, lower cost, lower consumption, monolithic integration, intellectualization, serialization and standardization. Utilizing surface micromachining process, a method for manufacturing thin moving diaphragm has been successfully achieved in this paper. The thickness of moving diaphragm is only 3μm so that the sensitivity of the sensor for low pressure range has increased.Research of the low pressure MEMS sensor has been formed by the following three aspects: structural design, finite element analysis and manufacture process. The goal of this paper is solving relevant technical difficulties in the realization of low pressure measurement. When taking into account the goal, the overall structure has been worked out; combined with theoretical analysis, ANSYS software has been conducted to simulate properties of the sensor; the main process of the sensor chip has been designed based on surface micromachining and key process has been explored to decide specific parameters. Finally, the uniform pressure test for the fabricated chip has been completed. The sensitivity of the chip is 0.007pF/kPa, laying theoretical and technical foundation for applicable low pressure MEMS sensor within the range of 50 kPa.