Aluminum oxide thin films were deposited on the P-type Si wafer by electron cyclotron resonance chemical vapor deposition methods using trimethylaluminum(TMA), $O_2$ and Ar gases. The deposition characteristics of the film such as deposition rate, refractive index were investigated as a function of the deposition parameters. The used deposition parameter were $O_2$/TMA ratios, microwave power, plasma Ar flow, deposition pressure and deposition temperature. The refractive index of the deposited films are in the range 1.62-1.64 and the deposition rate are between 70-80A/min. The $O_2$/TMA ratios necessary to the stable deposition are affected by the deposition temperature. As the deposition temperature increased from 95℃ to 160℃, this ratio varies from 8 to 12. As the deposition pressure increased from 0.3mtorr to 0.9mtorr, the film quality such as the refractive index, wet etch rate are degraded exclusively. The AES and FTIR measurement show that O/Al ratio of deposited films are in the range 1.6-1.7, that small amounts of carbon are included in the films asimpurities andthat hydrogens in the form of OII are not detected in the films. The OES analysis shows that TMA are dissociated very effectived by ECR plasma.
