AVS 49th International Symposium
    Thin Films Wednesday Sessions
       Session TF-WeP

Paper TF-WeP3
Deposition of ZnO Films by Reactive Sputtering in CO@sub 2@ Atmosphere

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Poster Session
Presenter: N. Aomine, Asahi Glass Co., Ltd., Japan
Authors: N. Aomine, Asahi Glass Co., Ltd., Japan
K. Sato, Asahi Glass Co., Ltd., Japan
E. Shidouji, Asahi Glass Co., Ltd., Japan
J. Ebisawa, Asahi Glass Co., Ltd., Japan
Correspondent: Click to Email
Transparent oxide films are often deposited by reactive sputtering from metal target in Ar/O@sub 2@ atmosphere because of cheep target cost. It is well known that deposition rate and absorbance of obtained films change drastically with a ratio of O@sub 2@ flow to total gas flow, and a transparent film can be obtained with a maximum deposition rate in the transition region from metallic to oxide mode. However, it is difficult to keep sputtering process in the transition region without monitoring plasma state e.g., emission, impedance, gas fraction, feed-backing to the process. In this work, reactive sputtering using CO@sub 2@ gas instead of Ar/O@sub 2@ gas was studied. ZnO films were deposited by reactive sputtering of a 10 cm-diameter Zn metal target. Process-film property relationship such as discharge voltage, deposition rate, film absorbance, and carbon content was investigated. Furthermore, gas fraction of CO@sub 2@ sputtering atmosphere was analyzed by quadrupole mass spectrometer (Q-mass). It was found that CO@sub 2@ sputtering has advantage to enable reactive sputtering in the transition region by only simply adjusting CO@sub 2@ flow rate. Films obtained with small CO@sub 2@ flow rate were absorptive, while films, with increasing CO@sub 2@ flow rate, became transparent and deposition rate finally began to decrease. Result from Q-mass spectra, showing CO@sub 2@ was partially decomposed into O@sub 2@ and CO by glow discharge, was analyzed based on gas supply and consumption balance model. It was concluded that CO@sub 2@ sputtering was advantageous owing not only to low O@sub 2@ partial pressure but also to deoxidation effect by CO. The advantage of CO@sub 2@ sputtering will be detailed.