Annealing behavior of oxygen in-diffusion from SiO2 film to silicon substrate

Abstract

Diffusion behavior of oxygen at (near) the Si∕SiO2 interface was investigated. We first oxidized the floating-zone-grown silicon substrates, and then annealed the SiO2-covered substrates in an argon ambient. We examined two different conditions for oxidation: wet and dry oxidation. By the secondary-ion-mass spectrometry, we measured the depth profiles of the oxygen in-diffusion of these heat-treated silicon substrates: We found that the energy of dissolution (in-diffusion) of an oxygen atom that dominates the oxygen concentration at the Si∕SiO2 interface depends on the oxidation condition: 2.0 and 1.7eV for wet and dry oxidation, respectively. We also found that the barrier heights for the oxygen diffusion in argon anneal were significantly different for different ambients adopted for the SiO2 formation: 3.3 and 1.8eV for wet and dry oxidation, respectively. These findings suggest that the microscopic behavior of the oxygen atoms at the Si∕SiO2 interface during the argon anneal depends on the ambient adopted for the SiO2 formation.