Advancement in Micromachining Techniques of MEMS Piezoresistive Pressure Sensors to Minimize Offset Drift Due to Humidity and Temperature

*Bagur Rudrappa Deepu, Belthangady Pavithra, Mangalore Manjunatha Nayak and Kunchinadka Narayana Bhat*

### **Abstract**

The present chapter focuses on the micromachining technology advancement to enhance the silicon micromachined piezoresistive pressure sensor's output characteristics. The differential pressure sensors with a glass bond or a passivation layer of Cr/ Au metals at the device's rear side are fabricated using MEMS techniques. The sensors with modifications can minimize and almost eliminate the absorption/adsorption of moisture content on the sensor surface for a long time, indicating improved device performance. The effect of atmospheric temperature and humidity on the four piezo resistors and the sensor's drift is investigated in this chapter, highlighting the challenges involved in glass micromachining techniques, including wet etching, sandblasting, and electrochemical discharge machining (ECDM). Ultimately, the fabricated sensor's pressure calibration and offset drift values are studied due to atmospheric effects being reported.

**Keywords:** MEMS, differential piezoresistive pressure sensor, passivation layer, glass micromachining, sandblasting, electrochemical discharge machining, sensor's drift
