Effect of Halogen in High-Density Oxygen Plasmas on Photoresist Trimming

摘要

Effects of halogens,CF_4,Cl_2,or HBr,on the photoresist trimming in high-density oxygen plasmas for sub-0.1-mum device fabrication were studied in an inductively coupled plasma (ICP) etcher.The trim rates were measured as a function of halogen gas percentages.The activation energy and the resulting resist profiles were investigated as well,showing that the CF_4/O_2 gives the highest trim rate,followed by HBr/O_2 and then Cl_2/O_2 at the same amount of additive gas in the mixture.Effects of different plasma chemistry on the chemical constituents of the resist sidewall films were also examined with the angle-resolved X-ray photo-electron spectroscopy (XPS).XPS analysis reveals that all halogen gases are useful for resist sidewall protection because of the passivation by the halogen-containing polymer.The effects of halogen addition include the reaction enhancement,reaction-site competition between oxygen and halogen,changes in the plasma gas chemistry,and the resist passivation.