A MICROSTRUCTURAL STUDY OF LOW-RESISTIVITY TIN-DOPED INDIUM OXIDE PREPARED BY DC MAGNETRON SPUTTERING

The microstructure of low resistivity (approximately 2 x 10(-4) OMEGA CM) Sn-doped In2O3 (ITO) thin films prepared by multipass d.c. magnetron sputter deposition with an ITO (10 wt.% SnO2) target onto soda-lime glass substrates was investigated using plan-view and cross-sectional transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction. Each pass of the multipass sputter process deposits a 110 nm thick ITO layer. The substrate temperature was 400-degrees-C during deposition and the sputter chamber was back-filled to a pressure of 1 x 10(-3) Torr with a mixture of Ar and 0.8-1.0 at.% O2. Plan-view TEM studies combined with SEM observations of the film surface reveal that the sputtered ITO possesses a polycrystalline structure in which 200-350 nm grains are subdivided into highly oriented regions 10-30 nm in diameter. X-ray diffractometry studies show that the as-deposited films have a strong [100] texture and cross-sectional TEM studies reveal prominent columnar growth in the through-thickness direction.