a semiconductor manufacturing process enables a complex multi - layer , silicon based mems devices , such as a gyroscope or accelerometer to be formed without using silicon on insulator substrates and obviates the need to purchase and use soi wafers as starting materials . the disclosed techniques further allows the etching of the sacrificial oxide to be “ head started ” prior to fusion bonding , thereby reducing the amount of release etching required at the end of the mems wafer processing .