Patent ID: 7651921

Claim:
A method of forming a contact post and a respective isolation trench in respect of an active semiconductor device region of a semiconductor-on-insulator substrate, said substrate comprising a base semiconductor substrate layer, a layer of insulating material on said base semiconductor substrate layer over which layer of insulating material is provided an active semiconductor layer within which an active semiconductor device can be formed, the method comprising forming a contact hole and surrounding trench, said contact hole extending from a surface of said active semiconductor layer to said base semiconductor substrate layer and said surrounding trench extending from a surface of said active semiconductor layer to said layer of insulating material, providing the sidewalls of said trench with a dielectric layer, completely filling said surrounding trench with a dielectric or substantially non-conductive semiconductor material and partially filling said contact hole with a dielectric or substantially non-conductive semiconductor material and filling said contact hole the rest of the way with a substantially conductive semiconductor so as to form a conductive contact post.