Identification and Removal of Storage Induced Particle Contamination on Silicon Wafer Surfaces

Control of contamination on the surface of wafers during the manufacture of state-of-the-art microcircuits is imperative if high yields are to be obtained. Hence, wafers are often cleaned using a modified RCA clean to remove organic, metallic and particle contamination prior to microcircuit manufacture. Recently, wafers obtained from a particular vendor were found to have heavy particle contamination after a modified RCA clean. The wafers were also found to have a hydrophobic surface indicating the presence of heavy organic contamination. Analysis of the wafer surface revealed that it was covered with film of a polydimethylsiloxane-like compound. The source of the compound was found to be a gasket in the storage boxes used to transport the wafers. This paper describes the methodology used to identify the source of the contaminant and the cleaning methods developed to eliminate the particle contamination which it caused.