Cleaning of Si Surfaces by Lamp Illumination

Cleanin of silicon surfaces using lamp illumination in ambient air at atmospheric pressure (ROST process) was investigated. It is demonstrated that an increase of wafer temperature up to 300°C by white light illumination for 30 seconds is sufficient to remove most volatile contaminants from the Si surface. Organic contaminants originating from wafer storage and handling ambient as well as from IPA drying are easily removed by ROST. This process is very effective in suppressing uncontrolled variation of the apparent thickness of ultra-thin oxide resulting from organic contamination. Furthermore, the process is efefctive in removing pseudo-volatile contamination such as sulfuric acid but not non-volatile contamination such as salts and metallic ions. In general, the efficiency of lamp cleaning decreases for contamination deposited during ling wafer storage times.