Low SiO 2/Si interface state density for low temperature oxides prepared by electron cyclotron resonance oxygen plasma

Abstract

The interface state densities of SiO 2 films were investigated. Films of SiO 2, 250 Å thick were grown by electron cyclotron resonance diffusion method using O 2 plasma at a substrate temperature of 200 °C for 40 min and these films were annealed at 600 °C for 60 min in N 2 gas. The oxygen to Si ratio was 2.02–2.13 throughout the films, indicating uniform SiO 2 stoichiometry that was identical to high temperature thermal oxide. The range of interface state density value before annealing was 2 × 10 11–1 × 10 12 eV −1 cm −2. But the value after annealing was 2.2 × 10 9–1 × 10 10 eV −1 cm −2. It is assumed that the positive ions (O 2 + 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 × 10 9 eV −1 cm −2. This represents the lowest interface state density value achieved to date.