Study On SiC High Temperature Buried Shear Stress Sensor

The materials Silicon-Carbide are very suitable for the development of MEMS microelectronic devices in high temperature due to its good thermal conductivity,high temperature resistance,high breakdown field strength and large forbidden band width.In this paper,a high temperature buried shear stress sensor with full carbonized silicon material has been developed through MEMS processing technology,aiming at the detection of shear stress under high temperature conditions.First of all,the design and simulation of the whole and part of the shear stress sensor are completed.Combined with the actual MEMS processing technology,the overall manufacturing process of the shear stress sensitive core is drawn up.Then,based on this,the preparation process of thick nickel mask of SiC material,plasma ICP deep etching process,hydrophilic bonding process,thinning process,etc.were explored.Thereby the fabrication of sensitive core was completed.And its packaging and performance test were carried out.The main contents of the article are as follows:(1)The overall structural scheme of the shear stress sensor is proposed,and the key structures such as floating unit,elastic support beam and sensitive comb are specially designed.And then the four layouts required in the process of shear stress sensor are completed.The COMSOL calculation simulation software was used to simulate the static core structure,modal and electromechanical coupling of the designed sensitive core structure,and the feasibility of the designed structure was verified.(2)The article selected Ti-Cu metal seed layer,through the study of SU-8 thick glue lithography process,the mother film pattern with good line and high steepness of the rubber wall was obtained on the seed layer.Based on the experiment of nickel sulfamate micro-electroforming system,the thick nickel metal mask which meets the subsequent SiC deep etching is micro-electroformed by the best process parameters.(3)The SiC plasma ICP deep etching process was systematically investigated.The parameters of etching gas and its flow rate,coil power,lower electrode power and etching temperature were analyzed,Then the hydrophilic bonding of SiC-SiC substrate was carried out.And the thinning of the SiC composite sheet,and the process is connected in series according to the process flow,and finally the flow sheet of the shear stress sensitive core is completed.(4)Perform the final overall encapsulation of the sensitive core and build a shear stress test system to test the performance of the prepared shear stress sensor.