Etching Characteristics of ZnO and Al-Doped ZnO in Inductively Coupled Cl_2/CH_4/H_2/Ar and BCl_3/CH_4/H_2/Ar Plasmas

摘要

ZnO and Al-doped ZnO (AZO) were etched in Cl_2/CH_4/H_2/Ar (Cl_2-based) and BCl_3/CH_4/H_2/Ar (BCl_3-based), inductively coupled plasmas (ICPs) and their etching characteristics were compared by varying the Cl_2/(Cl_2 + CH_4) and BCl_3/(BCl_3 + CH_4) flow ratios, top electrode power and dc self-bias voltage (V_(dc)). The etch rates of both ZnO and AZO layers were higher in the Cl_2-based chemistry than in the BCl_3 -based chemistry. The AZO and ZnO etch rates were increased and decreased, respectively, with increasing Cl_2 or BCl_3 flow ratio. Optical emission measurements of the radical species in the plasma and surface binding states by optical emission spectroscopy (OES) and X-ray photoelectron spectroscopy (XPS), respectively, indicated that, with increasing Cl_2 or BCl_3 flow ratio; the effective removal of Al in the AZO enhanced the AZO etch rate, whereas the reduced removal of Zn by the Zn(CW_x)_y products reduced the ZnO etch rate.