A new source/drain germanium-enrichment process comprising Ge deposition and laser-induced local melting and recrystallization for P-FET performance enhancement

Abstract

We report for the first time a new process technology for boosting the Ge content in SiGe source/drain (S/D) stressors to increase strain and performance levels in p-FETs. By laser-induced local melting and intermixing of an amorphous Ge layer with an underlying Si0.8Ge0.2 S/D region, a graded SiGe S/D stressor is formed upon recrystallization. Peak Ge content in the graded SiGe S/D is doubled over the as-grown film. Raman analysis confirmed the retention of high S/D strain levels due to the rapid non-equilibrium recrystallization process. The new process technology developed here employs several simple additional steps, including amorphous Ge deposition and laser anneal (LA). For a p-FET with Ge enriched S/D, 21% and 12% IDsat enhancement at a fixed IOFF of 2 × 10-8 A/μm is observed over control p-FETs with Si0.8Ge0.2 S/D formed by RTA and LA, respectively. © 2008 IEEE.