A Si3N4 etch process using a Plasmatherm 2406 etcher and SF6 was determined. RS1/Discover was used to design an experiment which varied SF6 flow rate, power, and pressure. ~ maximum nitride etch rate of 1300 ~/min. was obtained with a corresponding nitride to oxide selectivity of 2:1. Selectivities as high as 6:1 were obtained but with nitride - etch rates of less than 100 ~/min. ~n acceptable baseline process, having a nitride to oxide selectivity of 3.24:1 with a nitride etch rate of greater than 850 A/mm was established.
Espin, Gregg D.
"Selective Etching of LPCVD Si3N4 Over Si02 Using SF6,"
Journal of the Microelectronic Engineering Conference: Vol. 4
, Article 15.
Available at: http://scholarworks.rit.edu/ritamec/vol4/iss1/15