Effects of oxygen on selective silicon deposition using disilane

摘要

Using Si_2H_6 in an ultrahigh vacuum rapid thermal chemical vapor deposition reactor, we have investigated the role of high levels of oxygen (>5 x 10~-6 Torr) introduced during selective silicon deposition. The effects of oxygen have been investigated with regard to oxygen incorporation, selectivity with respect to thermal SiO_2, growth rate, and epitaxial quality. The addition of oxygen was found to enhance the inherent process selectivity of Si_2H_6 to SiO_2 while causing no reduction in the silicon growth rate or measureable oxygen incorporation into the growing film for oxygen pressures below 5 x 10~-5 Torr. Contrary to published reports, the silicon film was devoid of the pyramidal defects usually characteristic to highly oxygenated processes. The silicon surface morphology, however, exhibited increased roughness with increasing oxygen partial pressure. The surface roughness is believed to be a result of the high levels of oxygen adsorbed at the initial growth surface.