Patent ID: 7932158

Claim:
A method for forming a semiconductor-on-insulator (SOI) substrate, comprising: forming a substrate structure comprising at least a base semiconductor substrate layer and a semiconductor device layer with a sacrificial layer located therebetween; patterning the substrate structure to form one or more device regions defined by one or more isolation trenches, wherein each device region comprises a base semiconductor substrate layer and a semiconductor device layer with a sacrificial layer located therebetween; forming one or more insulator strips each having at least a vertical portion over a sidewall of one of the isolation trenches and a horizontal portion over an upper surface of one of the device regions; selectively removing the sacrificial layer from each device region to form an air gap between the base semiconductor substrate layer and the semiconductor device layer, wherein the vertical portions of the one or more insulator strips form vertical insulator pillars to support the semiconductor device layer; and filling the air gap within each device region with an insulator material to form a buried insulator layer between the base semiconductor substrate layer and the semiconductor device layer, wherein after patterning of the substrate structure and before formation of the insulator strips, lateral etching is carried out to selectively remove a peripheral portion of the sacrificial layer in each device region, so that the vertical portions of the subsequently formed patterned insulator strips comprise ledges that extend between the base semiconductor substrate layer and the semiconductor device layer at each device region.