Macromolecular Contamination on Haze Generation in Amorphous-Silicon Film by CVD: Controlled with Ozonized Water Treatment

Abstract

Focusing on macromolecular contaminants, we conducted a study on the quality of a film deposited by chemical vapor deposition (CVD). Si wafers (, P100) were coated with a polyethylene oxide (PEO) aqueous solution (, 0.2%) and left at room temperature. They were cleaned with a SC1 solution (, ) for . A film of amorphous silicon (a-Si) was deposited by CVD. Localized defects, commonly called haze, were observed in the resultant film. A thermal-desorption analysis of the residual PEO after the cleaning step revealed the abnormal desorption-peak shift from 400 up to . This shift far beyond the deposition point of is responsible for the haze generation. After the cleaning step, aggregates of residual PEO were observed at several spots on the wafer surface. The Raman spectra of the residues suggested the existence of the peptide links, (CO)–CNH, which may be induced by the reaction of PEOs with during SC1 cleaning. Strong interaction between the peptide links may have caused the aggregation observed. Ozonized water treatment prior to SC1 was found to be effective in removing PEO contaminants and preventing the haze from generating.