Crystallinity and texturing of RF sputtered c-axis aligned crystal InGaZnO 4 (CAAC IGZO) thin films were quantified using X-ray diffraction techniques. Above 190 C, nanocrystalline films with an X-ray peak at 2h ¼ 30 (009 planes) developed with increasing c-axis normal texturing up to 310 C. Under optimal conditions (310 C, 10% O 2 ), films exhibited a c-axis texture full-width half-maximum of 20 . Cross-sectional high-resolution transmission electron microscopy confirmed these results, showing alignment variation of 69 over a 15 Â 15 nm field of view and indicating formation of much larger aligned domains than previously reported. At higher deposition temperatures, c-axis alignment was gradually lost as polycrystalline films developed. V C 2014 AIP Publishing LLC. [http://dx.
This paper examines the correlation between deposition parameters and crystallinity, texture, and etch rate of reactively sputtered c-axis aligned crystalline (CAAC) IGZO films. Both X-ray diffraction and general area detector diffraction (GADDS) showed that crystallinity increases rapidly above 200 • C with simultaneous formation of highly aligned CAAC. Optimal texture with a c-axis alignment and a minimum GADDS full-width-at-half-maximum of 18 • occurred at 250 • C, with c-axis alignment decreasing at higher temperatures to a FWHM of 35 • at 385 • C. Chemical etch rate in 5 vol% HCl was highly correlated to crystallinity, dropping by a factor of ten in CAAC compared to amorphous IGZO; etch rate hence provides a highly sensitive measure of crystallinity.
Crystallinity and texture of c-axis aligned crystal indium gallium zinc oxide (CAAC IGZO) films deposited by RF reactive sputtering were studied and characterized over a range of deposition conditions. The characteristic CAAC (009) peak at 2θ=30 o was observed by X-ray diffraction, and nanocrystalline domain texture was determined using a general area detector diffraction system (GADDS). Highly ordered CAAC films were obtained near the InGaZnO4 composition at a substrate temperature of 310 o C and in 10% O2. High-resolution transmission electron microscopy (HRTEM) confirmed the formation of CAAC showing 2-3 nm domains aligned over 15 nm x 15 nm fields of view. Cross-section HRTEM of the CAAC/substrate interface shows formation of an initially disordered IGZO layer prior to CAAC formation, suggesting a nucleation mechanism similar to ZnO thin films.
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