Patent ID: 9236265
Filing Date: 2016-01-12
CPC Classification: H01J,H01L

Claim Text:
1. A method of etching silicon germanium, the method comprising: flowing a fluorine-containing precursor into a remote plasma region fluidly coupled to a substrate processing region via through-holes in a showerhead; flowing a diluent gas into either the remote plasma region or the substrate processing region; forming a remote plasma in the remote plasma region to produce plasma effluents; and etching the silicon germanium from a patterned substrate disposed within the substrate processing region by flowing the plasma effluents into the substrate processing region through the through-holes in the showerhead, wherein the diluent gas controls diffusion of the plasma effluents in a boundary layer adjacent to the patterned substrate, wherein the patterned substrate further comprises secondary exposed regions of silicon germanium having a lower germanium atomic percentage than the silicon germanium, and wherein the silicon germanium is etched faster than the secondary exposed regions of silicon germanium, wherein each point on an exposed surface of the silicon germanium of is within 0.5 μm of one of the secondary exposed regions of silicon germanium.