A study was performed on the etch characteristics of silicon dioxide and polysilicon for a reactive ion etch system, using CHF4 as the primary etchant gas and using either oxygen or carbon dioxide as an additive gas. Correlations were found between the amount and type of additive gas introduced to the system, the Rf power of the - system, the pressure that the system is maintained at and the effects these parameters have on the etch rate and - selectivity of Si02 and polysilicon etches. It was found that adding CO2 in small amounts to the gas mixture instead of pure oxygen had the effect of making the etch process more predictable and easier to control.
Constantino, James E.
"Reactive Ion Etching of Silicon Dioxide Using Both Oxygen and Carbon Dioxide as Gas Additives,"
Journal of the Microelectronic Engineering Conference: Vol. 4
, Article 8.
Available at: http://scholarworks.rit.edu/ritamec/vol4/iss1/8