Kinetics and compositional dependence on the microwave power and DiH4/N flow ratio of silicon nitride deposited by electron cyclotron resonance plasmas

Abstract

Silicon nitride layers have been deposited at a low temperature, 150ºC in an electron cyclotron plasma from nitrogen and silane as gas precursors. Deposition conditions have been varied in a wide range. Nitrogen flows from 25 to 400 sccm and silane flows from 2.5 to 35 sccm have been used in our experiments. The microwave power was varied from 100 to 1500 W. The result of the nitride growth kinetics show strong dependence on the silane to nitrogen flow ratio and on the microwave power. For large flow ratios and small powers the kinetics exhibits a nearly linear behavior whereas for low flow ratios and high powers a saturated regime was observed. Ellipsometry, infrared spectroscopy, and etch rate studies showed that the best material quality, 95% Si3N4, is obtained in the saturated regime for the lowest flow ratios and the highest powers used.