Patent ID: 6964926

Claim:
A method of forming capacitors having geometric deep trenches, comprising: providing a substrate; forming a pad structure on the substrate; forming a first hard mask layer on the substrate; forming a patterned second hard mask layer on the first hard mask layer to expose a first opening; forming a spacer layer in the first opening on the first hard mask layer to expose a second opening; forming a third hard mask layer to fill the second opening; removing the spacer layer to expose the first hard mask layer; etching the first hard mask layer, with the second hard mask layer and the third hard mask layer acting as masks, to form a third opening with a salient of the first hard mask layer therein; removing the second hard mask layer and the third hard mask layer; and etching the first hard mask layer, the salient of the first hard mask layer, the pad structure, and the substrate to form a geometric deep trench in the substrate.