Advanced activation and deactivation of arsenic-implanted ultra-shallow junctions using flash and spike + flash annealing

Millisecond annealing as an equipment technology provides ultra-sharp temperature peaks which favours dopant activation but nearly eliminates dopant diffusion to form extremely shallow highly electrically-activated junctions. On arsenic beamline implanted wafers the formation of ultra-shallow junctions at peak temperatures ranging from 1275 °C to 1325 °C was investigated. The thermal stability of these junctions was evaluated by subsequent thermal anneals ranging from 250 °C to 1050 °C with times ranging from seconds up to several hundred seconds. From these data the deactivation/reactivation mechanism for subsequent annealing can be quantified. Furthermore, the combination of spike and flash annealing is investigated to achieve a desired level of dopant diffusion and activation. For arsenic by far the lowest sheet resistance number is achieved by this annealing strategy. Finally, the arsenic profiles are compared to predictive simulation results which address the diffusion and activation at extrinsic concentrations.