Characteristics of germanium dry etching using inductively coupled SF ₆ plasma

Inductively coupled SF ₆ plasma etching of germanium (Ge) was investigated at different inductively coupled plasma (ICP) power levels, the SF ₆ flow rate, and the working pressure. The etch rate of Ge increases from 1007 to 2447 nm/min as the SF ₆ 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 SF ₆ 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 SF ₆ plasmas has been obtained using X-ray photoelectron spectroscopy. Reaction layers on germanium due to inductively coupled SF ₆ plasma etching are found to be a thin, layer with of G - S, Ge-F and Ge-O bonded species.