Experimental and theoretical results of dopant activation by a combination of spike and flash annealing

The diffusion length of the flash anneal is lowest for all different implant conditions. For the arsenic implant similar diffusion length is seen for all the processes that include a spike anneal due to the fact that the overall thermal budget is mainly determined by the spike anneal. Boron implants into crystalline as well as pre-amorphized silicon show similarly low sheet resistance independent of whether they are annealed with spike + flash, flash or flash + spike. For the arsenic implant by far the lowest sheet resistance is seen with a combination of spike + flash anneal. For the boron and arsenic implants the defect density after the flash anneal and the spike + flash anneal is below the weak beam dark field detection limit of the transmission electron microscope therefore suggesting low leakage due to defects present. From the simulations of the arsenic and the boron concentration profiles it can be learned that the spike profile determines the position of the chemical profile and the activation is increased by the subsequent diffusion-less flash anneal. Thus junction depth can be easily adjusted by the spike anneal condition in a spike + flash scheme, while still maintaining a high degree of dopant activation. This offers great flexibility to next generation junction formation. Although in this study the spike and flash annealing were performed in different tools, a combination of spike + flash can be easily run in the Mattson fRTPtrade system. The combination of spike + flash anneals also has been shown to improve the transistor drive current significantly without undesirable shifts in the other transistor characteristics.