Patent ID: 7569489

Claim:
A method for forming a semiconductor device, comprising: forming a layered substrate comprising at least a base semiconductor substrate layer, an insulator layer over the base semiconductor substrate layer, and a semiconductor device layer over the insulator layer, wherein the semiconductor device layer has upper and lower surfaces oriented along a first set of equivalent crystal planes; patterning the semiconductor device layer to provide at least two 3D precursory semiconductor structures, wherein a second 3D precursory semiconductor structure is masked and a first 3D precursory semiconductor structure is exposed; and conducting preferential crystallographic etching of the first 3D precursory semiconductor structures, wherein said first 3D precursory semiconductor structure is etched along the first set of equivalent crystal planes at a rate faster than that along a second, different set of equivalent crystal planes, thereby forming the first 3D semiconductor structure having the bottom surface and the multiple additional surfaces, wherein the bottom surface of the first 3D semiconductor structure is oriented along one of the first set of equivalent crystal planes, and wherein the multiple additional surfaces of the first 3D semiconductor structure are oriented along the second, different set of equivalent crystal planes.