In situ XPS and SIMS analysis of O ₂ ⁺ beam‐induced silicon oxidation

The chemical composition variation of silicon under 4 keV O 2 + ion beam bombardment at different incident angles was studied by in situ small‐area XPS. The changes in secondary ion profile ( 30 Si + , 44 SiO + , 56 Si 2 + , 60 SiO 2 + ) during oxygen ion beam bombardment also have been monitored. We present a direct correlation of the changes in secondary ion depth profile with surface composition during sputtering. Evolution of the secondary ion profile obtained from SIMS shows similar trends with variation of oxygen concentration in the crater surface measured by XPS. It is shown that when the oxygen ion beam incidence angle is < 40° silicon dioxide is the dominant species on the crater surface and the matrix ion species ratio (MISR) value for 44 SiO + / 56 Si 2 + is higher than for 30 Si + / 56 Si 2 + . For incidence angles of >40°, the formation of sub‐oxide is favoured and thus the MISR value for 44 SiO + / 56 Si 2 + is lower than for 30 Si + / 56 Si 2 . At 40° bombardment there are similar amounts of SiO 2 and sub‐oxides present on the crater surface and the MISR values for 44 SiO + / 56 Si 2 + and 30 Si + / 56 Si 2 + are also similar.