Low Energy Hydrogen Ion-Beams in Silicon Processing

An investigation to study the effects of low energy hydrogen ion-beams in silicon processing was performed. It was found that exposing Si to a beam of low energy ions induced extensive lattice damage at the Si surface. However, this damage was found to be transparent electrical measurements, which suggested that H passivated its self-induced damage. The H passivation studies were extended to include point defects in the semiconductor bulk. These studies indicate that the role of H ions in altering the concentration of active traps in the semiconductor could be explained, in a unifying manner, by taking into account the interaction of Si interstitials with point defects in the Si bulk. These interstitials are created at the Si surface when it is bombarded by energetic ions. Shallow acceptor neutralization was seen in the bulk of boron-doped, Ar('+)- or H('+)-bombarded Si, when the sample temperature during the ion-beam exposure was kept below 60(DEGREES)C. Although these results strongly suggest that the compensation effect is not H related, the possibility of H contamination of Si, from water vapor in the vacuum chamber, prevented the author from completely ruling out H induced compensation as the cause of acceptor compensation. A tentative model, involving interstitial phenomenon was proposed to explain the compensation of the shallow acceptors. Finally, using H as a passivating agent, a novel process to fabricate ion-implanted junctions using low-temperature (T < 600(DEGREES)C), was demonstrated for both majority- and minority-carrier devices. The implications of this research have also been discussed.