Low SiO2/Si interface state density for low temperature oxides prepared by electron cyclotron resonance oxygen plasma

The interface state densities of SiO2 films were investigated. Films of SiO2, 250 Å thick were grown by electron cyclotron resonance diffusion method using O2 plasma at a substrate temperature of 200 °C for 40 min and these films were annealed at 600 °C for 60 min in N2 gas. The oxygen to Si ratio was 2.02–2.13 throughout the films, indicating uniform SiO2 stoichiometry that was identical to high temperature thermal oxide. The range of interface state density value before annealing was 2 × 1011–1 × 1012 eV−1 cm−2. But the value after annealing was 2.2 × 109–1 × 1010 eV−1 cm−2. It is assumed that the positive ions (O2+ or O+) in the bulk of the oxide can neutralize the interface state density during annealing. The best interface state density value was 2.2 × 109 eV−1 cm−2. This represents the lowest interface state density value achieved to date.