Thick SOI wafers are widely used in power devices and MEMS to achieve high breakdown voltage, low energy consumption and high performance of MEMS. This is possible due to their SOI structure. We use a bonding method in the manufacture of thick SOI wafers and exercise more precise control over the thickness of the SOI layer and the BOX layer. The demand for SOI wafers in leading-edge devices such as intelligent power modulus, which require high breakdown voltage and low energy consumption, is also increasing. More over MEMS made of SOI brings complex 3-D structure such as accelerometer and pressure sensor.