A method of forming an electrical contact between a carrier wafer and the surface of an upper silicon layer of a silicon-on-insulator wafer and electrical device having such an electrical contact

摘要

A method of forming an electrical contact between a carrier wafer (12) and a surface of an upper silicon layer (16) of a silicon on insulator wafer to set the carrier wafer (12) at a defined potential, the method comprising the steps of Etching a cavity (20) in the top silicon layer (16) and in the insulator layer (14), performing a selective epitaxial step of growing an epitaxial layer of silicon in the cavity (20) to the surface of the top silicon layer (16) in that, by adjusting the width of the cavity (20) with respect to the thickness of the top silicon layer (16), the surface of the silicon epitaxial layer filling the cavity (20) has the same crystal orientation as the surrounding surface of the top silicon layer (16). , wherein subsequently an epitaxial step for growing a further layer (24) made of silicon is performed, where the further silicon layer (24) covering the surface of the silicon epitaxial layer filling the cavity (20) and the surface of the top silicon layer (16), the further silicon layer (24) being grown after removal of an oxide mask ,