Formation of shallow p(+)n junctions using different annealing schemes with low thermal budget

The formation of shallow p(+)n junctions by directly implanting BF2 dopant into the Si substrates and then treating the samples by different annealing schemes with a low thermal budget has been studied. Nosignificant dopant d iffusion is observed by using these annealing processes with a low thermal budget. After conventional furnace annealing (FA) at a medium temperature o f 800 degrees C for 30 min, the resulting junction characteristics are poor . A low-temperature long-time FA treatment at 600 degrees C for 2 h, prior to the medium-temperature FA treatment, can considerably improve the juncti on formation. Furthermore, shallow p(+)n junctions with a leakage smaller t han 10 nA/cm(2) can be achieved by an annealing scheme that employs low-tem perature FA followed by medium-temperature rapid thermal annealing (RTA) at 800 degrees C for 30 s. However, an annealing process that employs medium- temperature RTA at 800 degrees C for 30 s followed by low-temperature FA tr eatment cannot produce good junctions. In addition, the low-temperature ann ealing time of 2-3 h is found to be sufficient for forming good shallow p()n junctions in the annealing scheme that employs low-temperature FA follow ed by medium-temperature RTA.