Patent ID: 7985676

Claim:
A method for forming a semiconductor device, the method comprising: after forming a gate and a source/drain region of a transistor, forming an etch stop layer over a conductive region; forming an insulating layer over the etch stop layer; forming a pattern transfer layer adjacent an upper portion of the insulating layer, the pattern transfer layer being patterned in the reverse tone of a layout of recesses to be formed in the insulating layer such that the pattern transfer layer remains over regions where the recesses are to be formed; forming a conductive mask material over the insulating layer, the conductive mask material being self-aligned with the pattern transfer layer, wherein forming a conductive mask material comprises: depositing a layer of the conductive mask material, and performing a chemical mechanical polish step to remove any conductive mask material from over portions of the pattern transfer layer; removing remaining portions of the pattern transfer layer; and forming a contact hole having continuously vertical sidewalls by etching recesses in the insulating layer using the conductive mask material as a mask.