We investigated the etching characteristics of zinc oxide (ZnO) and the effect of additive gases in a Cl 2 -based inductively coupled plasma. The inert gases were argon, nitrogen, and helium. The maximum etch rates were 44.3, 39.9, and 37.9 nm/min for Cl 2 (75%)/Ar(25%), Cl 2 (50%)/N 2 (50%), and Cl 2 (75%)/He(25%) gas mixtures, 600 W radiofrequency power, 150 W bias power, and 2 Pa process pressure. We obtained the maximum etch rate by a combination of chemical reaction and physical bombardment. A volatile compound of Zn-Cl. achieved the chemical reaction on the surface of the ZnO thin films. The physical etching was performed by inert gas ion bombardment that broke the Zn-O bonds. The highly oriented (002) peak was determined on samples, and the (013) peak of Zn 2 SiO 4 was observed in the ZnO thin film sample based on x-ray diffraction spectroscopy patterns. In addition, the sample of Cl 2 / He chemistry showed a high full-width at half-maximum value. The root-mean-square roughness of ZnO thin films decreased to 1.33 nm from 5.88 nm at Cl 2 (50%)/N 2 (50%) plasma chemistry.
In this study, the etching characteristics of HfAlO 3 thin film were investigated by varying the etch parameters such as the gas mixing ratio, the radio frequency power, the direct current bias voltage, and the process pressure in an inductively coupled plasma. The maximum etch rate of HfAlO 3 thin film and the selectivity of HfAlO 3 to SiO 2 were 20.55 nm/min and 0.38 in the CF 4 /Cl 2 /Ar (2:6:14 sccm) plasma, respectively. The plasma was analyzed by using optical emission spectroscopy. The chemical states on the surfaces of the etched HfAlO 3 thin film were investigated with X-ray photoelectron spectroscopy. The etching of HfAlO 3 thin films is performed by the interaction of Hf and Al atoms with the Cl and F radical in the CF 4 /Cl 2 /Ar plasma. However, their byproducts were remained at the surface because Hf-F and Al-F were non-volatile. Therefore, the plasma etching of the HfAlO 3 films follows the ion assisted chemical reaction.
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