μ-Raman investigations of plasma hydrogenated silicon

Abstract

Standard [001]-oriented p- (12–20 Ω cm) and n-type (1.8–2.6 Ω cm) Czochralski (Cz) silicon wafers were treated by a RF (13.56 MHz) hydrogen plasma at a substrate temperature of 250 °C. After the plasma hydrogenation subsequent annealing was applied up to 600 °C in air. The formation of H2 molecules in voids/platelets was investigated by Raman spectroscopy. The Raman intensities of the H2 vibration modes at ~4150 cm−1 exhibited significant intensity modulations in dependence on the annealing temperature. The intensities of the H2 Raman lines indirectly monitor the evolution of the voids/platelets upon annealing. This assumption was verified by cross-sectional transmission electron microscopy (XTEM), which was applied for comparison. The intensity modulations of the H2 Raman signal can be explained by the evolution of and platelets. At lower annealing temperatures (<500 °C) platelets laying in planes are dominant, while at elevated temperatures (≥500 °C) [001]-oriented platelets become more and more important. platelets were also observed using XTEM measurements in p-type material. In case of p-type substrates the Raman intensities were significant higher than for n-type material. The higher H2 Raman intensities in p-type Cz Si can be explained by the amphoteric character of hydrogen in silicon.