Applied Surface Science, Vol.357, 672-677, 2015
Growth of amorphous zinc tin oxide films using plasma-enhanced atomic layer deposition from bis(1-dimethylamino-2-methyl-2propoxy)tin,diethylzinc, and oxygen plasma
Amorphous ZnSnOx (ZTO) films were prepared using plasma-enhanced atomic layer deposition (PEALD) in a temperature range of 100-200 degrees C. Metal-organic precursors of Sn(dmamp)(2) (dmamp = bis(1-dimethylamino-2-methyl-2-propoxide) and diethylzinc were employed as sources of Sn and Zn, respectively, in combination with O-2 plasma as a reactant. Sn levels in the ZTO films were controlled by varying the SnO2/ZnO cycle ratio from 0 to 8. According to the growth behaviour of the ZTO film by alternating SnO2 and ZnO PEALD cycles, it was observed that ZnO growth on Sn-rich ZTO film is retarded, whereas SnO2 growth is enhanced on Zn-rich ZTO film. The chemical states of the ZTO films were confirmed by X-ray photoelectron spectroscopy (XPS); the chemical compositions of the ZTO films were characterised by XPS depth profiling. Grazing-angle X-ray diffraction revealed that the PEALD ZTO films possess an amorphous structure, irrespective of Sn levels from 20 to 59 at.%. ZTO films with intermediate Sn at.% exhibited smooth surface morphology compared to binary ZnO and SnO2 films. Additionally, the step coverage of a ZTO film deposited on hole pattern with an aspect ratio of 8 and opening diameter of 110 nm was about 93%, suggesting the realisation of self-limited growth. (C) 2015 Elsevier B.V. All rights reserved.