Al2O3 thin films prepared by plasma-enhanced chemical vapor deposition of dimethylaluminum isopropoxide

Al2O3 thin films were deposited by plasma-enhanced chemical vapor deposition using a dimethylaluminum isopropoxide precursor in the absence of additional oxygen sources. The deposition rate ranged from 0.77 to 1.07 Å/s and increased with increasing deposition temperature between 300 and 500 °C. The O/Al ratios in the films deposited at 300-500 °C were ~ 1.5, consistent with the formula Al2O3 and the carbon contents were 8.3-9.7 at.%. The film deposited at 30 °C had relatively higher values of O/Al ratio (2.04) and carbon content (47.1 at.%). Al2p, O1s, and C1s peaks observed from X-ray photoelectron spectroscopy analysis were mainly attributed to Al2O3. Fourier transform infrared analyses indicated that the functional groups such as Al2O3 bending and stretching vibrations were primarily from Al2O3 species with some carbon contents. From the dry etching test, the Al2O3 film deposited at 400 °C had the high etch selectivity of 9.13 over SiO2, which showed the potential for application to the dry etch hard mask material.