Journal of Vacuum Science & Technology A, Vol.28, No.4, 890-894, 2010
High rate reactive magnetron sputter deposition of Al-doped ZnO with unipolar pulsing and impedance control system
Al-doped ZnO (AZO) films were deposited on quartz glass substrates, unheated and heated to 200 degrees C, using reactive sputtering with a special feedback system of discharge impedance combined with midfrequency pulsing. A planar Zn-Al alloy target was connected to the switching unit, which was operated in a unipolar pulse mode. The oxidation of the target surface was precisely controlled by a feedback system for the entire O-2 flow ratio including "the transition region." The deposition rate was about 10-20 times higher than that for films deposited by conventional sputtering using an oxide target. A deposition rate of AZO films of 390 nm/min with a resistivity of 3.8 X 10(-4) Omega cm and a transmittance in the visible region of 85% was obtained when the films were deposited on glass substrates heated to 200 degrees C with a discharge power of 4 kW. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3308621]