Research On Design And Key Processes Of The Sensing Chip For High Performance MEMS Inclinometers

The inclination is an important parameter that must be detected and controlled in the field of mechanical engineering,building bridge,transmission line tower and platform stability.And the inclinometer is a kind of angle measuring device,which is the angle of the measuring plane and the reference plane.Compared with the traditional inclinometers,the MEMS inclinometers have been rapidly occupying the building,vehicle transportation,consumer electronics,aerospace and defense security,and the ratio of market has increased year by year with high performance and small volume.In the early beginning of the study of MEMS inclinometers,the high performance MEMS inclinometers based on multiple principles has been introduced,which can cover the vast majority of the inclination measurement.However,in the process of design and micrograph manufacturing technology,there is a long-standing technical block in China.Therefore,it is of great strategic significance to develop the MEMS high performance inclinometers with independent intellectual property rights,and to break the foreign monopoly and technical block,solve the defense and industrial field precision.The MEMS inclinometer is essentially a MEMS accelerometer with a small range and narrow bandwidth.The trigonometric function between gravity acceleration and tilt Angle is used to convert the two sensors.According to the principle of work can be divided into capacitive,resonant,photoelectric principle,which is based on the "sandwich" structure of capacitive MEMS inclinometer in measuring accuracy,environmental adaptability,processing difficulty and cost can reach a great balance,in the field of high performance inclinometers accounts for more than half of the market share.Therefore,it is of great significance to break through the design and key technology of this kind of sensor.This paper mainly studies the structure design,micro/nano manufacturing process and other key technologies of capacitive MEMS inclinometers sensitive chip based on "sandwich" structure.The main research contents are as follows:1.Introduce the principle and structure of various MEMS inclinometers,summarize the research status at home and abroad,compare the advantages and disadvantages of various MEMS inclinometers,and put forward the main research content and innovation points of this paper.2.The working mechanism of beam-mass structure of MEMS inclinometers sensitive chip was analyzed,mathematical,mechanical and electrical models of the sensitive chip were established,and the relationship between the key size of the sensitive chip and its performance parameters was obtained.Based on the three-dimensional morphology of bulk silicon process,the finite element model of the sensitive chip was established,and the deflection and angle of the sensitive mass block were analyzed.The sensitivity,linearity and other performance parameters were further obtained,and the structural size of the sensitive chip was determined by iterative optimization.3.Research on micro/nano manufacturing process of MEMS inclinometers sensitive chip;design and planning of MEMS process flow based on the structure of sensitive chip;Key single-step process research has been completed,including beam-mass silicon processing,GIS cap processing,wafer level bonding and side electrode preparation.4.The zero bias stability,linearity,lateral sensitivity and resolution of the sensitive chip are tested and verified by the high precision capacitor detection circuit based on AD7745.Finally,the work completed in this paper is summarized,and the improvement direction of high-performance MEMS inclinometer is proposed according to the results measured by the detection circuit.