Preparation and Characterization of Time Dependent Haze on Silicon Surfaces

摘要

Occasionally an increase in number of localized light scatterers (LLS) is observed upon surface inspection after storage of silicon wafers in plastic boxes. This phenomenon, caused by chemical processes, is called time dependent haze (TDH). Different kinds of haze are known, originating for instance from organic additives in the packing material, which adsorb onto the surface, or from ionic contaminants originating from wet cleaning processes. The goal of our study is to generate artificial TDH in order to examine its causes and to work out appropriate characterization techniques to differentiate between different types of haze. The influence of inorganic ions such as ammonium, chloride, fluoride and sulphate and of organic compounds on the generation of TDH has been studied. With AFM / pulsed force measurements structure and contrast in materials exposed to haze can be achieved simultaneously. The resolution of AFM is also much better than that of scanning surface inspection systems (SSIS).