Es. Cielaszyk et al., MECHANISMS FOR POLYCRYSTALLINE SILICON DEFECT PASSIVATION BY HYDROGENATION IN AN ELECTRON-CYCLOTRON-RESONANCE PLASMA, Applied physics letters, 67(21), 1995, pp. 3099-3101
An in-line mass spectrometer and Langmuir probes have been employed to
examine mechanisms of plasma immersion hydrogen passivation of grain
boundary defects in polycrystalline silicon thin film transistors. Rel
ative fluxes of H+ and H-2(+) as well as total ion current density wer
e measured at the substrate location in an electron cyclotron resonanc
e hydrogen discharge. Measurements were made over a range of operating
conditions over which passivation rates have been shown to vary drama
tically. Data presented show a strong correlation of both H+ flux and
ion bombardment energy with good transistor performance obtained at op
erating pressures below 1 mTorr. This suggests that discharge operatin
g conditions that promote dissociation of H-2 to form H and H+ (which
may diffuse more rapidly through solid material than H-2), as well as
increased sheath voltages and therefore ion energy at the substrate, a
re important to obtaining acceptable process rates. (C) 1995 American
Institute of Physics.