Patent ID: 9583625
Date: 2017-02-28
CPC Classifications: H01L

Claim:
1. A method comprising: forming a silicon (Si) fin, the Si fin having an active top portion and an active bottom portion; forming a hard mask on a top surface of the Si fin; forming an oxide layer on opposite sides of the Si fin; implanting a dopant into the Si fin; recessing the oxide layer to reveal the active top portion of the Si fin; etching the active top portion of the Si fin to form vertical sidewalls; forming a nitride spacer covering each vertical sidewall, the nitrate spacer having a top and a bottom, wherein the top contacts the hard mask, and the bottom is closer than the top to the recessed oxide layer; recessing the recessed oxide layer to reveal the active bottom portion of the Si fin; and tapering the active bottom portion of the Si fin, such that the opposite sides of the Si fin extend in a straight line from a wider portion of the Si fin at the recessed oxide layer, which has been recessed, to a narrower portion of the Si fin where the Si fin contacts the bottom of the nitride spacer.