Heavy B atomic-layer doping characteristics in Si epitaxial growth on B adsorbed Si(1 0 0) by ultraclean low-pressure CVD system

Heavy B atomic-layer doping is performed by B atomic-layer formation on Si(1 0 0) using B₂H₆ and subsequent Si capping layer deposition using SiH₄. By B₂H₆ exposure on Si(1 0 0) at 180 °C, the B atom amount tends to saturate self-limitedly at around 1.4 × 10¹⁵ cm^-2 (two atomic layers (AL)). In the case of exposure at 500 °C, the B atom amount increases with time and exceeds two AL. Additionally, B oxide formation by air exposure is observed for 500 °C but not for 180 °C. Therefore, it is suggested that the H adsorption on the B AL is kept at 180 °C and H desorption from the B AL proceeds at 500 °C. It is also found that the SiH₄ exposure on the B AL at low temperatures such as 180-300 °C effectively improves the electrical activity of B and suppresses lattice strain generation even with the subsequent Si capping at 500 °C. These results demonstrate that the low temperature reaction of SiH₄ as well as B₂H₆ open the way to extremely heavy B atomic-layer doping.