Ultrashallow Junction Formation Using Low-Temperature Selective S i _1-x G e _x Chemical Vapor Deposition

In situ B doping and selective epitaxy on Si at 550° C in Si_{1- x} Ge _x chemical vapor deposition (CVD) have been investigated for forming high-performance ultrashallow junctions. It was found that the incorporation rate of B increased proportionally with increasing B₂H₆ partial pressure, and was higher for the film with a higher Ge fraction x. Using Si₃N₄, thermal SiO₂, phosphosilicate glass (PSG) and borophosphosilicate glass (BPSG) as mask film materials, about 40-nm-, 100-nm-, 150-nm- and 150-nm-thick B-doped Si_0.5Ge_0.5 films, respectively, were grown selectively on Si(100). Using this low-temperature selective Si_{1- x} Ge _x CVD, a high-performance self-aligned ultrashallow junction formation has been achieved with a very low reverse current density, in the range of 10^-10 A/cm², without heat treatment.