Activation of polysilicon connections by selective CW laser annealing

A new self-aligned procedure has been developed to connect polysilicon links on chip by using a CW argon laser. A silicon nitride mask serves as a diffusion barrier over part of the link during doping of the polysilicon, and later as an antireflection coating to couple the maximum amount of light into the undoped region during laser scanning. The laser melts this region only and dopant atoms rapidly diffuse in from the neighboring parts of the link. For the optimum mask length, 100 percent of the links were open circuits ( >15 MΩ) before irradiation, while the sheet resistivity was reduced to 12 Ω after processing.