Decaborane ion implantation for sub-40-nm gate-length PMOSFETs to enable formation of steep ultra-shallow junction and small threshold voltage fluctuation

In this paper, the decaborane molecular ion implantation for formation of an ultra-shallow junction of sub-40-nm PMOSFETs is investigated, and its high-performance are demonstrated. B₁₀H_x⁺ implantation can form a shallow and steep USJ with low resistivity and can precisely control the beam without blow-up and energy contamination, compared with the B⁺ monomer implantation. PMOSFETs using B₁₀H_x⁺ implantation for source/drain extensions achieve 6-nm shorter Vth roll-off characteristic without degradation of I_on-I_off characteristic. Therefore, CV/I values can be improved by over 10%. In addition, the precisely controllable and well-collimated beam results occur alongside the Vth fluctuation suppression. The average improvement of Vth fluctuations among extensive gate length (35 to 200 nm) is 14%.