Determination of the fixed oxide charge and interface trap densities for buried oxide layers formed by oxygen implantation

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Abstract
Capacitance-voltage measurements were used to analyze buried oxide layers formed by the implantation of oxygen into silicon substrates. The analysis is based on the extension of conventional metal/oxide/semiconductor capacitor theory to the two buried oxide interfaces of the epilayer/oxide/substrate structure. The processing parameters include oxygen doses of 1.8 or 2.0×1018 cm−2, implant temperature of 500 °C, and anneal temperature of 1250 °C for 2 or 16 h. The results are fixed oxide charge densities of 2–3×1011 and 1–2×1010 cm−2 for the epi/oxide and substrate/oxide interfaces, respectively; interface trap densities are 0.5 to 2×1011 cm−2 eV−1 for the epi/oxide interface, and not measurable for the substrate/oxide interface. The epilayer/oxide interface was found to be more sensitive to processing variations than the substrate/oxide interface.