Yasuhiko Akao

Development of Silver-Based Multilayer Coating Electrodes with Low Resistance for Use in Flat Panel Displays

Multilayer coatings consisting of thin silver layers sandwiched between layers of transparent conducting metal oxides were investigated from the view-point of low-resistance electrodes for use in flat panel displays. Optimization of the multilayer coatings resulted in a five-layer coating composed of indium and zinc oxide composite material (IZO) and silver containing 1 wt% of palladium (Ag–Pd). The coatings had satisfactory properties of low resistance, high transmittance, high moisture and alkali resistance, and good patterning.

Improvement of Alkali Durability of Silver-Based Multilayer Coatings for Use in Flat Panel Displays

Silver-based multilayer coatings are well known to be transparent films with low electrical resistivity. In particular, indium and zinc composite oxide (IZO)/silver containing palladium (AgPd) multilayer coatings have good pattering properties and durability. However, the IZO/AgPd multilayer coatings do not have sufficient alkali durability as transparent electrodes of flat panel displays (FPDs). In order to solve this problem, coatings covered with a protective layer of tin-doped indium oxide (ITO) were investigated. Over-coating of an ITO layer degraded the patterning properties of the multilayer coatings because the etching rates of ITO, IZO and AgPd layer were very different. From the viewpoint of controlling the etching rate of each layer independently, the etching solution composed of hydrobromic acid and iron chloride was adjusted, so that the ITO/IZO/AgPd/IZO/AgPd/IZO/substrate multilayer coatings could be fabricated into fine patterns for electrodes. The multilayer coatings thus prepared are more tolerable for alkali detergents used in the production process of FPDs.

Numerical simulation of plasma confinement in DC magnetron sputtering under different magnetic fields and anode structures

The plasma confinement between the electrodes in direct current magnetron sputtering has been investigated by using the two-dimensional hybrid model. We have quantitatively clarified plasma behavior for different magnetic fields and anode structures. The results show that plasma can be confined in the space near the sputtering target by applying a center-dominant magnetic array even in the absence of an anode facing the target (cathode). This knowledge is expected to be useful for film deposition on insulating materials such as glasses.