Study of High Temperature Reliability of Composite Passivation Layers for MEMS Orthotropic Sensors
Piezoresistive orthotropic pressure sensors prepared by silicon on insulator(SOI)can work well at high tempera-tures,but the resistive strip and metal leads are susceptible to oxidation and corrosion when exposed to the environment for a long time in high temperature environments,which affect the output of the sensors and change or even invalidate the electrical performance,and passivation is usually carried out on the surface in order to avoid this situation.In this paper,a composite passivation layer of silicon dioxide and silicon nitride was used to passivate the SOI orthotropic sensor chip,and the passivation layer was subjected to a high-temperature aging test to simulate high temperatures and harsh environments and verify its high-temperature reliability.The experimental results show that according to the silicon dioxide 200 nm,silicon nitride 300 nm silicon dioxide silicon nitride com-posite passivation layer can be at a high temperature of 350℃on the orthotropic sensors for effective protection and electrical performance is intact to meet the requirements of the chip reliability at high temperatures.
silicon on insulator(SOI)piezoresistive orthotropic pressure sensorscomposite passivation layerhigh temperature reliability