Novel wafer-scale uniform layer-by-layer etching technology for line edge roughness reduction and surface flattening of 3D Ge channels

We have developed a novel wafer-scale uniform layer-by-layer etching technology based on the etching reaction of oxygen molecules with Ge surfaces. The advantages of this etching technology are as follows. (1) Layer-by-layer etching can be achieved, yielding an atomically flat step-terrace surface. (2) Because of the very small activation energy (<0.1 eV) of the etching reaction, this technology is free from etch rate variation caused by temperature inhomogeneity over large wafers. (3) No plasma damage occurs as a result of O2 molecule reactions with anisotropic etching. These features are applicable to the fabrication of three-dimensional Ge channels.