Effects of oxygen on selective silicon deposition using disilane

Using Si2H6 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 oxyg en have been investigated with regard to oxygen incorporation, selectivity with respect to thermal SiO2, growth rate, and epitaxial quality. The addit ion of oxygen was found to enhance the inherent process selectivity of Si2H 6 to SiO2 while causing no reduction in the silicon growth rate or measurab le oxygen incorporation into the growing film for oxygen pressures below 5 x 10(-5) Torr. Contrary to published reports, the silicon film was devoid o f the pyramidal defects usually characteristic to highly oxygenated process es. The silicon surface morphology, however, exhibited increased roughness with increasing oxygen partial pressure. The surface roughness is believed to he a result of the high levels of oxygen adsorbed at the initial growth surface. (C) 1999 Elsevier Science B.V. All rights reserved.