Ryohei Satoh

Research on direct laser patterning of thin films for flat-panel display

On a microcircuit pattern, which is necessary for fabricating electrical devices such as plasma display and liquid crystal display, the wet process which utilizes lithography technology is commonly employed. The wet process, however, is not desirable because it needs a large number of process steps. Furthermore, chemical used in the process is hazardous to the environment. Therefore, a “dry process” that does not utilize the lithography is strongly desired. In this paper, to realize the dry process, a laser processing approach using a Nd:YAG laser is adopted as an alternative technology. We fabricate thin films made of SnO2 (a next generation material for transparent thin film electrodes for Flat-Panel Display (FPD)) under various conditions and examine the effectiveness of the laser processing approach via experiments with the thin films. We found that the film characteristics such as electrical resisivity, crystalline structure quality, and so on, change and that the effectiveness of the laser processing varies, depending on the conditions. In this work, we show that these results can be explained in terms of a wavelength shift in the absorption edge of the thin films for Nd:YAG laser from the viewpoint of interaction of light and electrons.On a microcircuit pattern, which is necessary for fabricating electrical devices such as plasma display and liquid crystal display, the wet process which utilizes lithography technology is commonly employed. The wet process, however, is not desirable because it needs a large number of process steps. Furthermore, chemical used in the process is hazardous to the environment. Therefore, a “dry process” that does not utilize the lithography is strongly desired. In this paper, to realize the dry process, a laser processing approach using a Nd:YAG laser is adopted as an alternative technology. We fabricate thin films made of SnO2 (a next generation material for transparent thin film electrodes for Flat-Panel Display (FPD)) under various conditions and examine the effectiveness of the laser processing approach via experiments with the thin films. We found that the film characteristics such as electrical resisivity, crystalline structure quality, and so on, change and that the effectiveness of the laser processin...