Masaaki Matsuda

Polymer resist materials for excimer ablation lithography

Abstract Excimer ablation lithography (EAL) is a new lithography suitable to TFT-LCD. Among the constituent technologies, the polymer materials for the resist is most crucial, as high ablation rates are required at low fluence. To elucidate the ablation mechanism at low fluence we specified some characteristic features through observations of about 200 polymers. The low fluence features are explained by the contributions from the primary and secondary structures, and ablation dynamic process. From the results, it is derived that polyurethane is most promising material for EAL, and the design of the secondary structure is essential to improve the ablation rate.

Excimer ablation lithography (EAL) for TFT-LCD

The excimer ablation lithography (EAL) is a process of direct patterning and removal of a resist polymer film by photo-decomposition ablation. Comparing to the conventional photolithography, EAL does not need the development process and realizes a non-vacuum dry removal of resist. The main equipment for the new processes is a kind of aligner- exposure for the resist patterning and the removal, which reduce the cost of the clean room and the equipments considerably. This is very attractive for TFT-LCD manufacturing, as it is required to reduce the cost severely. The large area patterning and high throughput are essential for TFT-LCD applications. To prove the feasibility, we fabricated an experimental equipment for ablation patterning. It is equipped with the high precision 300 X 300 mm X-Y stages and a N.A. 0.1 image lens which enable to explore the problems inherent to TFT panel of a real size. In addition, two substantial technologies were developed. One is a dielectric multilayer mask on 8 inch quartz substrate with precision enough for TFT patterns. The other is high ablation rate resist polymer. With these technologies, A4 size TFT laser was fabricated by step and scan method. The results show that EAL is in a good prospect for a new TFT manufacturing technology.

Polyurethane resins as resist materials for excimer ablation lithography (EAL)

The excimer laser ablation lithography (EAL) is a process of direct patterning and removal of a resist film by photo- decomposition ablation. Taking advantage of EAL process, we have tried to apply this process to LCD fabrication. As the most fundamental problem for resist materials is the ablation rate, we have examined to measure the ablation rates of many kinds of polymers. AMong them the most promising is the polyurethane (PU) which is synthesized from toluenediisocyanate and poly derivatives in chlorobenzene solution. The ablation rate at 100 mJ/cm2 fluence of 248 nm is more than 0.05 micrometers /shot, which is the highest value of all the materials that we have examined. Through the investigations of structures of PU, we could elucidate the mechanisms of the high ablation rate, and accordingly the molecular design concept of the ablation resist.

Polyurethane Resins as Resist Materials for Excimer Ablation Lithography(EAL)

The excimer laser ablation lithography(EAL) is a process of direct patterning and developing of a resist film by photo-decomposition ablation. Taking advantage of EAL process, we have tried to apply this process to LCD fabrication. As the most fundamental problem for resist materials is the ablation rate, we have examined to measure the ablation rates of many kinds of polymers. Among them the most promising is the polyurethane resin (PU) which is synthesized from toluenediisocyanate and poly(ethylene glycol) derivatives in chlorobenzene solution. The ablation rate at 100 mJ/cm2 fluence of 248 nm is more than 0.05 pm/shot, which is the highest value of all the materials that we have examined. Through the investigations of structures of PU, we could elucidate the mechanisms of the high ablation rate, and accordingly the molecular design concept of the ablation resist.