Flash lamp annealing in diluted oxygen for low sheet resistance and ultra-shallow junctions: Suppression of wet-cleaning-induced sheet-resistance degradation

We have investigated the process of flash lamp annealing (FLA) in a dilute oxygen ambient. The oxide grown during this process protects against wet chemicals and maintains the low sheet resistance (Rs). The influence of several wet chemical cleans after FLA on ultra-shallow junction (USJ) characteristics were evaluated, and it was found that wet chemical cleaning increased the Rs of the doped layer. In the worst case, the advantage (high activation) of FLA was substantially lost. We therefore proposed the formation of a capping oxide by adding oxygen to the ambient during the FLA process to prevent the increase of Rs, and to demonstrate its function in providing a highly-effective protective barrier.