Improvement of SiO2 / Si Interface Flatness by Post‐Oxidation Anneal

The effect of post‐oxidation anneal for improvement in interface flatness was examined. Si substrates with (100), (110), (111), (511), and (221) orientations were used. They were thermally oxidized and subsequently annealed in a pure Ar atmosphere for 5 min using a lamp, or for 1 h using a furnace annealer. The interfaces were characterized by HRTEM. The flatness of low‐index plane interfaces, such as (100), (110), and (111), was improved by post‐oxidation anneal. However, the high‐index interfaces of (511) and (221) were rather roughened with low‐index microfacets. A reaction at the interface is thought to occur during the high‐temperature post‐oxidation anneal. Low‐index plane interfaces, which are considered to have low interface energy, appear as a result of this reaction.