For the fabrication of a multilevel resist (MLR) based on a very thin, physical-vapor-deposited (PVD) amorphous carbon (a-C) layer, the etching characteristics of the PVD a-C layer with a SiOx hard mask were investigated in a dual-frequency superimposed capacitively coupled plasma etcher by varying the following process parameters in O2∕N2∕Ar plasmas: high-frequency/low-frequency combination (fHF∕fLF), HF/LF power ratio (PHF∕PLF), and O2 and N2 flow rates. The very thin nature of the a-C layer helps to keep the aspect ratio of the etched features low. The etch rate of the PVD a-C layer increased with decreasing fHF∕fLF combination and increasing PLF and was initially increased but then decreased with increasing N2 flow rate in O2∕N2∕Ar plasmas. The application of a 30nm PVD a-C layer in the MLR structure of ArF PR∕BARC∕SiOx∕PVD a-C∕TEOS oxide supported the possibility of using a very thin PVD a-C layer as an etch-mask layer for the TEOS-oxide layer.
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 =ðCl 2 þ CH 4 Þ and BCl 3 =ðBCl 3 þ CH 4 Þ 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(CH x) y products reduced the ZnO etch rate.
Articles you may be interested inInfinitely high etch selectivity during CH 2 F 2 / H 2 dual-frequency capacitively coupled plasma etching of silicon nitride to chemical vapor-deposited a -C
For fabrication of a multilevel resist (MLR) structure with silicon nitride (Si3N4) and amorphous carbon (a-C) layers, highly selective etching of the Si3N4 layer using a chemical vapor-deposited (CVD) a-C etch mask was investigated by varying the following process parameters in CH2F2/H2/Ar plasmas: etch gas flow ratio, high-frequency source power (PHF), and low-frequency source power (PLF) in a dual-frequency superimposed capacitively coupled plasma etcher. The results of etching the ArF photoresist/bottom antireflective coating/SiOx/CVD a-C/Si3N4 MLR structure showed the possibility of obtaining an infinitely high selective etch process for the Si3N4 layer using a thin CVD a-C etch mask for high aspect-ratio pattern formation. The CH2F2/H2 gas flow ratio was found to play a critical role in determining the process window for infinite Si3N4/CVD a-C etch selectivity, due to the change in the degree of polymerization on Si3N4 and CVD a-C surfaces.
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