Shallow Doping in Silicon

In recent years liquid-state diffusion by laser melting has been instituted in device manufacture; and annealing of doped polysilicon and ion implantation damage by various lasers and incoherent radiation sources have been investigated. Continuous wave (CW) laser annealing was shown to be superior in the reduction of polysilicon sheet resistance due to increase in grain size. Incoherent radiation sources appear to be practical for dopant activation with mimimum redistribution. The conventional furnace technology continues to play an important role while new technologies are introduced to complement it. These various technologies for shallow doping (> 1 µm) in silicon are reviewed in terms of cost, throughput, special process requirements, dopant activation, dopant profile shift, and device characteristics.