Patent ID: 8809172

Claim:
A method comprising: providing a semiconductor substrate having a deep implantation region and a peripheral region; forming a hardmask pattern having a high aspect ratio in the deep implantation region and a blanket hardmask in the peripheral region; performing a first ion implantation with a first conductivity-type dopant; depositing an etch stop layer, wherein the etch stop layer conformally coats the hardmask pattern; filling trenches between the hardmask pattern with a sacrificial filler material having a higher wet etch resistance than the hardmask; removing a top portion of the sacrificial filler material and the etch stop layer over a top surface of the hardmask pattern; removing the hardmask pattern in the deep implantation region by wet etching; performing a second ion implantation with a second conductivity type dopant opposite of the first conductivity type; and, removing remaining etch stop layer, the blanket hardmask in the peripheral region, and the sacrificial filler material.