Microwave plasma enhanced chemical vapor deposition in magnetic fields below electron cyclotron resonance

Abstract

Microwaveplasmas ( f=2.45 GHz, 200–1000 W) at magnetic fields below electron cyclotron resonance (ECR), B ce = 875 G, were used for room temperaturechemical vapor deposition of silicon nitridefilms.Plasmas were maintained in a nonresonant (with respect to any microwave mode) cavity at magnetic fields of 200–600 G, and were ‘‘extracted’’ with the divergent magnetic field into the process chamber. Silicon wafers of 10–20 cm diameters were positioned at 25 cm downstream in the process chamber. The total gas pressure was 0.7–2 mTorr and silane/nitrogen partial pressure ratio varied from 0.1 to 0.8. The film growth rate was 100–200 Å/min at a microwave power of 100–300 W and was found to be 15%–25% lower than in electron‐cyclotron‐resonance plasma streams. The index of refraction grew with silane partial pressure and was essentially the same as in ECR plasmafilms.