[17a-C101-1~11] 13.4 Si wafer processing /Si based thin film /Interconnect technology/ MEMS/ Integration technology

[17a-C101-9] Doping of Phosphorus to Poly-Si Thin Films Coated with Phosphoric Acid Solution by KrF Excimer Laser Irradiation

〇Kaname Imokawa^1,2, Nozomu Tanaka¹, Akira Suwa^1,2, Daisuke Nakamura¹, Taizoh Sadoh¹, Hiroshi Ikenoue¹ (1.Kyushu Univ., 2.Gigaphoton Next GLP Kyushu Univ.)

Keywords:Excimer Laser Doping, Low Temperature Poly-Si, Phosphoric Acid Solution Coating

We propose a high throughput, low CoO (cost of ownership), and damage free laser doping method for poly-Si TFT fabrication. In this method, solutions, including dopant atoms, are coated on the poly-Si surface, and dopant atom diffusion into the poly-Si film and activation can be simultaneously achieved by KrF excimer laser irradiation to the poly-Si films. In this method, the use of heavy manufacturing equipment such as ion implantation and furnace annealing systems are not necessary. In addition, it is a very simple method in which dopant coating and laser annealing processes are performed under atmospheric conditions. Therefore, we expect that this method will be available for doping processes in thin film devices for printable electronics.
In our previous study, we reported that laser doping of phosphorus to poly-Si thin films can be achieved using excimer laser irradiation in phosphoric acid solution. However, cavitation bubbles were generated on the irradiated area in the solution during laser irradiation such that laser irradiation damage to the poly-Si was induced by optical scattering of the laser light at the bubble/solution interface.
By irradiation to the poly-Si coated with the solution instead of irradiation in the solution, poly-Si films with no irradiation damage were obtained. In the case of using phosphoric acid as the coating solution, high quality n-type poly-Si thin films with no damage and low resistivity (~0.15 Ωcm) were fabricated.