| abstract |
A method for selectively etching SiO and SiN with respect to SiGe or Si of a structure is provided. A plurality of cycles of atomic layer etching is provided, where each cycle comprises a fluorinated polymer deposition phase and an activation phase. The fluorinated polymer deposition phase comprises flowing a fluorinated polymer deposition gas comprising a fluorocarbon gas, forming the fluorinated polymer deposition gas into a plasma, which deposits a fluorocarbon polymer layer on the structure, and stopping the flow of the fluorinated polymer deposition gas. The activation phase comprises flowing an activation gas comprising an inert bombardment gas and H 2 , forming the activation gas into a plasma, wherein the inert bombardment gas activates fluorine in the fluorinated polymer which with the plasma components from H 2 cause SiO and SiN to be selectively etched with respect to SiGe and Si, and stopping the flow of the activation gas. |