Excimer ablation lithography (EAL) for TFT-LCD

The excimer ablation Lithography (EAL) is a process of direct patterning and removal of a resist polymer Nm 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 a 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 enabe 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 '' quartz substrate with precision enough for TFT patterns. The other is high ablation rare resist polymer. With these technologies, A4 size TFT layer was fabricated by step and scan method. The results show that EAL is in a good prospect for a new TFT manufacturing technology.