Using a hydrogen ambient to eliminate interfacial boron spikes in reduced temperature silicon epitaxy

We show that the concentration of boron at the interface between a silicon epitaxial layer and an n-type Si substrate can be reduced to 109–1010 atoms cm−2, near the detection limit of secondary-ion mass spectrometry, when passivating oxide is desorbed from the substrate surface in a hydrogen ambient. Interfacial boron contamination is found to be much higher when the substrate surface oxide is desorbed in ultrahigh vacuum prior to growth, consistent with previous studies of Si molecular beam epitaxy. The hydrogen ambient is effective in removing boron only during the decomposition of the surface oxide.