Behavior of strained Si1−yCy (0⩽y⩽0.02) layers grown on silicon during wet oxidation

Abstract

We have investigated the properties of strained Si1−yCy(0⩽y⩽0.02) alloy layers grown on silicon after wet oxidation between 750 and 1100 °C. Both secondary ion mass spectrometry and x-ray photoelectron spectroscopy prove the presence of carbon in the oxide. The growth rates and refractive indices of the oxides obtained from ellipsometry show no significant differences compared with oxides grown on silicon. Infrared absorption measurements reveal decreasing stress in the oxides with rising oxidation temperature and a slight dependence of the stress in the oxide upon the carbon concentration. For the Si1−yCy layer, x-ray diffraction measurements show a decrease of the substitutional carbon concentration with increasing oxidation temperature and duration. This loss of substitutional carbon is enhanced near the SiO2/Si1−yCy interface. The formation of silicon carbide precipitates in the Si1−yCy layer is demonstrated by infrared absorption. For short oxidation times, we find an increase of the intensity of the local vibrational absorption mode of substitutional carbon. We observe discrepancies between the determination of the substitutional carbon concentration in the x-ray diffraction and infrared absorption measurements.