A study of antimony or arsenic implanted extensions with or without xenon pre-amorphization

We present in this paper a detailed analysis of the electrical behavior of NMOS transistors where the source/drain extensions (SDE) were doped either by As, Xe pre-amorphizing implant (PAI) + As, Sb or Xe PAI + Sb. The Sb splits show better threshold voltage characteristics in comparison with As: delayed Vt rolldown, reduced Short Channel Effect (SCE) and Drain Induced Barrier Lowering (DIBL). Moreover, the I_on/I_off trade-off analysis reveals that more than 10% improvement in the performance can be obtained with Sb compared to the As reference that is due to a reduction in the access resistance R_access. This makes Sb a very promising candidate for N-type Ultra-Shallow Junctions (USJ) for future CMOS generations. Xe PAI induces excellent sub-threshold characteristics due to the lowering of the junction depth Xj; however the I_on is dramatically reduced in this case because of much higher R_access.