Patent ID: 8232149

Claim:
A method for manufacturing an SOI device, comprising the steps of: defining grooves in an SOI substrate having a stacked structure by etching a first silicon layer and a partial thickness of a buried oxide layer of the SOI substrate, wherein the SOI substrate has a structure including the buried oxide layer and the first silicon layer sequentially stacked on a silicon substrate wherein each of the grooves is defined to have a bulbous-shaped section by forming the grooves using a vertical shaped groove and a substantially spherical shaped groove that is mated to a lower end of the vertical shaped groove such that the spherical shaped groove is defined in a lower portion of the first silicon layer and partially in the buried oxide layer; forming an insulation layer on surfaces of the spherical shaped groove while selectively forming the insulation layer only on the lower end of the vertical shaped groove while a spacer is on an upper end of the vertical shaped groove which prevents the insulation layer from being formed on the upper end of the vertical shaped groove; forming a second silicon layer as a body of the SOI device to fill the grooves that have the insulation layer formed therein; forming gates on the second silicon layer; and forming junction regions in the first silicon layer on both sides of the gates to contact the insulation layer and the buried oxide layer of the SOI substrate, thus the second silicon layer is floated by the presence of the junction regions and the buried oxide layer.