| AVS 56th International Symposium & Exhibition | |
| Thin Film | Thursday Sessions |
| Session TF-ThP |
| Session: | Aspects of Thin Films Poster Session |
| Presenter: | N. Tsukamoto, Aoyama Gakuin University, Japan |
| Authors: | N. Tsukamoto, Aoyama Gakuin University, Japan D. Watanabe, Aoyama Gakuin University, Japan N. Ito, Panasonic Electric Works Co., Ltd., Japan N. Oka, Aoyama Gakuin University, Japan Y. Sato, Aoyama Gakuin University, Japan Y. Shigesato, Aoyama Gakuin University, Japan |
| Correspondent: | Click to Email |
Magnetron sputtering processes using ceramic oxide targets have been used to deposit transparent conductive Al doped ZnO films because of its advantages for large area uniform coatings with high packing density and strong adhesion. However, the degradations of electrical properties and crystallinity for ZnO films have similarly been observed at the positions opposite to the erosion track on the target. These are considered to be caused by the bombardment of high energy particles such as energetic Ar atoms (high energy neutrals) or negative oxygen ions. In this study, we tried to detect the flux and energy distributions of high energy negative ions during the dc magnetron sputtering using an AZO target and discussed the influence of high energy negative ion bombardments on the structure and electrical properties of the films.
High energy negative ions were analyzed using a quadrupole mass spectrometer combined with an electrostatic energy analyzer, which was positioned at the substrate position opposite to the AZO (Al2O3: 2.0 wt%) target. The sputtering power during the analyses was maintained at 50 W. The O2 flow ratio [O2 / (Ar+O2)] were controlled from 0 to 5 %. For the analysis of the flux of the negative ions at the different substrate locations, the sputtering target was perpendicularly moved to the quadrupole mass spectrometer. In order to control the cathode voltage, the magnetic field strength was selected as 0.025, 0.06 and 0.1 T. In order to discuss the influence of the bombardments on the film properties, AZO films were deposited on unheated alkali-free glass substrate under the same condition of the fragment analysis. The atomic oxygen negative ion (O-) was observed as the high energy negative ions which possessed the energy corresponding to the cathode sheath voltage. The maximum flux of O- was observed at the location opposite to the erosion track on the target. The flux of O- decreased slightly with increasing O2 ratio. These results indicate that high energy negative ions were not formed by electron attachment in the cathode sheath region but should be sputtered from the target surface. Depending on the magnetic field strength, the cathode voltage varied from 337 V at 0.1 T to 403 V at 0.025 T. While the peak of O- shifted to lower energies with increasing the magnetic field strength, the flux of O- was hardly changed. The lower the energy of the peak of O- which AZO films is deposited at is, the lower both of resistivity and crystallinity for AZO films which are deposited at the positions opposite to the erosion track on the target are.