Abstract
A new thinning technique is developed to control thickness variation in Si-on-insulator (SOI) bonded wafers. During KOH etching, voltage is applied between the supporting substrate and the etchant. Excellent SOI thickness variation of less than ±0.1 µm is achieved by etching 4±0.5 µm thick, 150 mmφ SOI bonded wafers. The resulting film thickness after etching is controlled from 0.8 to 2.6 µm by changing the applied voltage from 50 to 75 V.