μ-Raman investigations of plasma hydrogenated silicon

¹ University of Hagen, PO Box 940, 58084 Hagen, Germany
² University of Poitiers, 86962 Futuroscope Chasseneuil Cedex, France

Corresponding author: reinhart.job@fernuni-hagen.de

Received: 23 May 2002
Revised: 23 August 2002
Accepted: 30 August 2002
Published online: 25 February 2003

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.