Effect of excimer laser annealing through oxide

We investigated the effects of the crystallization of a-Si film with a capping oxide by 308 nm XeCl excimer laser. It is related to the process of impurity activation after ion doping and the uniformity improvement of excimer laser crystallization through oxide. The 50 nm PECVD a-Si film was deposited on PECVD oxide with a thickness of 300 nm. Then the sample was heated to reduce the hydrogen content in the a-Si thin film. A PECVD oxide was deposited on the dehydrogenated a-Si layer. The thickness of capping oxide ranges from 100 nm to 400 nm. When a capping oxide was used as a hard mask for ion doping or suppressing the deviation of laser energy, the thickness of capping oxide plays an important role in the laser activation or crystallization process. In this study we discuss the effect of the thickness of capping oxide on the laser crystallization or activation process. Good correlation between the interference effect (capping oxide thickness) and laser crystallized film quality was observed.