Electron cyclotron resonance plasma stream source for plasma enhanced chemical vapor deposition

Abstract

An electron cyclotron resonance (ECR) plasma stream source at a frequency of 2.45 GHz was explored and utilized for SiO2 film chemical vapor deposition (CVD). It was found that for high and uniform plasma stream density the large limiting ring and magnetic fields higher than 930 G are required in the ECR plasma chamber. Plasma densities of(4–6)×1010 cm−3 in nitrogen and (6–8)×1011 cm−3 in argon with uniformities of ±5% over an area of 12 cm in diameter were achieved at distances of 30 to 50 cm from the source limiting ring at a microwave power range of 500 to 600 W. The etch of thermal silicon dioxide and polysilicon with CF4 showed uniformity better than ±1% over 5-in. wafers at a distance of 19 cm. SiO2 films were deposited in a mixture of 15% SiH4/N2 and O2 at substrate temperatures of 30 to 200 °C. Room-temperature ECR films had characteristics better than those obtained in conventional plasma enhanced CVD films deposited at 300 °C. ECR films deposited at 200 °C had properties which approach those of thermal silicon oxide.