Mechanism and rapid process of YAG laser process on SnO2 system thin films

Nano-second pulsed Nd:YAG laser (1064nm) process on SnO2 system thin films on glass as transparent electrode for Flat Panel Displays(FPD) was investigated in this paper. Mechanism of laser ablation, which is an interaction between material and laser, was studied to approach low energy process for mass production application. It was found that carrier concentration is an important factor influencing the process from energy absorption mechanism of free electron vibration induced by laser. The process needed high carrier concentration for low energy process. Experiments showed threshold of the process was about 4.0x1025m-3 of carrier concentration. However, some showed exception of successful process with even low carrier concentration. Then an additional mechanism that YAG photon (1.16eV) excites electrons trapped at deep level to conductive band was inferred. Deep level was measured by cathode luminescence spectroscopy, and result showed existence of electron at less than 1.16eV. It is understood that SnO2 system thin films absorb laser energy through complex process of free electrons vibration and deep level electrons excitation. Considering the mechanisms, it is the first to achieve 20mJ/mm2 of low energy process. This result leads to high process speed and good prospect of the laser process for mass production application for FPD.