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

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.