Boron at Si/SiO2 interface in SOI wafers and consequences for piezoresistive MEMS devices

Paper in proceeding, 2008

BESOI wafers are commonly used for MEMS fabrication and their quality is thus of great importance for the functionality and reliability of the device. It is therefore important to be aware that there is a manufacturing problem with boron impurity at the Si/SiO2 layer in the SOI wafer This impurity is not specified when purchasing the wafer and can alter the background doping up to several μm:s from the BOX, resulting in non-functional piezoresistive devices and unwanted limitation in membrane thickness. In this work we present guidelines on how to detect and counteract this impurity.