MEMS and sensors
Why are SOI wafers often used in MEMS fabrication?
- ABecause SOI wafers are the cheapest wafers
- BBecause the top silicon layer can serve as the structure, and the buried oxide as an etch stop or sacrificial layer
- CBecause SOI wafers do not transmit light
Show answer and explanation
Answer: B. Because the top silicon layer can serve as the structure, and the buried oxide as an etch stop or sacrificial layer
In an SOI wafer, the top single-crystal silicon layer has a precisely uniform thickness, so it can be used directly as the material for movable structures. Deep etching stops at the buried oxide, and removing that oxide frees the structure, making SOI convenient for MEMS fabrication.