Chemical and electrical dopants profile evolution during solid phase epitaxial regrowth

Abstract

Solid phase epitaxial regrowth (SPER) is a promising method for junction formation of sub-65 nm complementary metal–oxide–semiconductor technology nodes. This is mainly due to a high dopant activation level, easy control over electrical junction depth, excellent abruptness, and limited boron diffusion. In the present research we investigate in detail the activation process and the chemical profile change after SPER junction activation with respect to the regrowth temperature. We also obtain the electrically active profiles. We find that the process window for SPER between T=620 °C and T=740 °C offers the best activation level and has a dopant profile similar to the as-implanted. While increasing the regrowth temperature, we observe the gradual increase of the transient enhanced diffusion effect and formation of B trapping centers in the end-of-range (EOR) region. At temperatures as high as T=800 °C and T=850 °C the dopant activation beyond the original a-Si layer is observed and the high metastable B activation in the junction drops dramatically. All these changes can be associated with release of Si interstitials from the EOR region due to dissolution of 〈311〉 defects.