FABRICATION AND DOPING OF POLY-SIGE USING EXCIMER-LASER PROCESSING

Pulsed Laser-Induced Epitaxy (PLIE)/Gas Immersion Laser Doping (GILD) offers several advantages over alternative epitaxial processes, especi ally because the process can be made spatially selective. Here, a puls ed XeCl excimer laser is used to grow poly-Si1-xGex layers with Ge fra ctions up to 30 % by intermixing a structure of electron beam-evaporat ed a-Ge on poly-Si deposited on quartz. Arsenic or boron dopant is inc orporated during the melt process by using, respectively, an AsF5 or B F3 gas ambient. RBS and SIMS analysis reveal that the Ge metallurgical depth, the dopant junction depth and the incorporated dopant dose sca le with the laser energy density and the number of laser pulses. The s heet resistance values reached after GILD process are low enough to be suitable for the fabrication of source and drain for poly-SiGe TFTs.