Characteristics of germanium dry etching using inductively coupled SF6 plasma

Inductively coupled SF6 plasma etching of germanium (Ge) was investigated at different inductively coupled plasma (ICP) power levels, the SF6 flow rate, and the working pressure. The etch rate of Ge increases from 1007 to 2447 nm/min as the SF6 flow rate increases from 10 to 60 sccm. Also, the etch rate of Ge increases from 265 to 1007 nm/min as the ICP power level increases from 100 to 400 W whereas the etch rate of Ge decreases from 552 to 295 nm/min as the working pressure increases from 5 to 20 mTorr. The etch profile is isotropic. As SF6 flow, ICP power and working pressure decrease the surface roughness decreases. Optical emission spectroscopy was used to examine the gas phase species in the plasma, and emission from excited atomic S and F has been identified. Composition of the surface due to SF6 plasmas has been obtained using X-ray photoelectron spectroscopy. Reaction layers on germanium due to inductively coupled SF6 plasma etching are found to be a thin, layer with of G–-S, Ge–F and Ge–O bonded species.