Dry etching of germanium by using Inductively coupled CF ₄ plasma

Inductively coupled plasma (ICP) etching of germanium was investigated in a CF ₄ Plasma. The Ge etch rates were determined as a function of the CF ₄ flow rate, the ICP power and the working pressure. The etch profile is always anisotropic. As the CF ₄ flow rate and the ICP power decrease, the surface smoothness increases whereas the surface smoothness decreases as the working pressure decreases. Optical emission spectroscopy (OES) was used to examine the gas phase species in the plasma and emissions from excited atomic C and F were identified. The composition and the thickness of the reaction layers on germanium due to the CF ₄ plasmas were obtained by using X-ray photoelectron spectroscopy (XPS). The reaction layer on germanium due to inductively-coupled CF ₄ plasma etching was found to be typically very thin Ge-F and C-F layer.