D26 Journal of The Electrochemical Society, 159 (1) D26-D30 (2012) 0013-4651/2012/159(1)/D26/5/$28.00 © The Electrochemical Society The Dry Etching Characteristics of HfAlO3 Thin Films in CF4/Cl2/Ar Inductively Coupled Plasma

In this study, the etching characteristics of HfAlO3 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 HfAlO3 thin film and the selectivity of HfAlO3 to SiO2 were 20.55 nm/min and 0.38 in the CF4/Cl2/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 HfAlO3 thin film were investigated with X-ray photoelectron spectroscopy. The etching of HfAlO3 thin films is performed by the interaction of Hf and Al atoms with the Cl and F radical in the CF4/Cl2/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 HfAlO3 films follows the ion assisted chemical reaction. © 2011 The Electrochemical Society. [DOI: 10.1149/2.033201jes] All rights reserved. Manuscript submitted August 11, 2011; revised manuscript received October 7, 2011. Published December 8, 2011. When the channel length is scaling down to increase the speed and density, the thickness of the gate dielectric also must be reduced. However, reducing the thickness of SiON or SiO2 to less than 1.5 nm is problematic, as the gate leakage current increases due to direct-tunneling.1–4 One solution to this problem is the replacement of SiO