Evaluation of the chemical states and electrical activation of ultra-highly B-doped Si1-xGex by ion implantation and subsequent nanosecond laser annealing.

[Display omitted] • The NLA treatment prevents undesired dopant-diffusion and removes defects induced by ion-implantation in the near-surface region, effectively achieving highly active B concentration over approximately 1021 cm−3. • Using XPS, new chemical bonding states related to Si-B and Ge-B bonds in the near-surface region were identified in XPS Si 2 p and Ge 3 d spectra, which show the substitutionality of B-atoms upon NLA process. • Based on the depth profiles of the B 1 s peaks from the surface to melted depth, the relative ratios of active state in the NLA-treated films were confirmed and compared with the electrical activation rate measured by Hall measurements. Given that transistor dimensions are approaching atomic scale in metal–oxide–semiconductor field-effect-transistors (MOSFETs), attaining low-contact resistivity (ρ c) between contact-metal and Si is a primary challenge for source/drain (S/D) fabrications. To reduce ρ c , it is necessary to increase active dopant concentration in the semiconductor region underneath the contact-metal. High-dose ion-implantation and nanosecond laser-annealing (NLA) have been intensively investigated to produce highly activated layers in S/D regions. Particularly for the B-doped SiGe layers, which are used as S/D stressor for p-MOSFETs, non-substitutional B species are generated in the highly doped films at concentrations exceeding ∼ 1021 cm−3. These non-substitutional B are electrically non-activated and thus should be minimized to reduce ρ c. In this study, we investigated the chemical states and electrical activation in highly B-doped SiGe layer. Using X-ray photoelectron spectroscopy (XPS), we examined the substitutionality of B-atoms and identified new chemical states of Si-B and Ge-B bonds in Si 2 p and Ge 3 d peaks. In the B 1 s spectra, electrical activation states are determined by quantifying relative area ratios of the active/inactive B peaks, which are well matched with activation rates calculated by Hall measurements. Our findings systematically explained the activation behavior of NLA-treated B-doped SiGe films in high B-concentration ranges. [ABSTRACT FROM AUTHOR]