The influence of Cr content on the phase structure of the Al-rich Al-Cr-O films deposited by magnetron sputtering at low temperature

Abstract The Al-rich Al-Cr-O films were directly deposited on Si(100) substrate by reactive radio frequency magnetron sputtering (RFMS) using Al-Cr alloy targets. The elemental composition and phase structure of the films deposited from alloy targets with different Cr content at low substrate temperature were analyzed by electron probe microanalysis (EPMA), grazing incident X-ray diffraction (GIXRD) and transmission electron microscopy (TEM). The results show that the single corundum structured (Al 0.7 Cr 0.3 ) 2 O 3 solid solution films could be successfully synthesized by sputtering the Al 70 Cr 30 target at low substrate temperature of 550 ℃. The phase structures of the films deposited from Al 80 Cr 20 target exhibit a mixture of Al-rich α-(Al x Cr 1-x ) 2 O 3 , Cr-rich α-(Al x Cr 1-x ) 2 O 3 , γ-Al 2 O 3 and amorphous phases when the substrate temperature was lower than 550 ℃. The formation of γ phase could be suppressed at 600 ℃ while few amorphous alumina still remains in the film. In order to deposit single phase corundum-type Al-rich (Al x Cr 1-x ) 2 O 3 solid solution films at low temperature, the sufficient Cr content in the films is required.