Ultrashallow Junction Formation Using Low-Temperature Selective Si1-xGex Chemical Vapor Deposition

Abstract

In situ B doping and selective epitaxy on Si at 550° C in Si1-x Gex 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 Si0.5Ge0.5 films, respectively, were grown selectively on Si(100). Using this low-temperature selective Si1-x Gex 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.