Application of selective epitaxy for formation of ultra shallow SiGe-based junctions

Selective epitaxial growth (SEG) of B-, P- and As-doped Si1 − xGex (0.12 < x < 0.26) layers on patterned substrates, aimed for source/drain ultra shallow junctions was investigated. The SiGe layers were deposited selectively on Si surface that is either unprocessed or previously in situ etched by HCl in the same run in a reduced pressure chemical vapor deposition reactor. In these investigations selectivity mode, pattern dependency (loading effect), defect generation and dopant incorporation in SiGe layers have been discussed. It was demonstrated that the growth rate increased in presence of B in SiGe while it decreased for P- and As-doped layers. The amount of Ge was constant for B-doped samples while it increased for As- and P-doped SiGe layers. The epitaxial quality was dependent on the Ge amount, growth rate and dopant concentration. The selectivity mode of the growth was dependent on B partial pressure, however, no effect was observed for P- or As-doping in SiGe layers. A resistivity value of ∼10−3 Ω cm was obtained for B- and P-doped SiGe layers with optimized growth parameters.