An electron cyclotron resonance plasma stream source for low pressure thin film production

Abstract

Electron cyclotron resonance plasma stream sources of our own design suitable for use in low pressure (10-4 - 10-3 Torr), low temperature chemical vapor deposition were characterized. It was found that a high level of absorption of microwave power (more than 95%) occurred when the plasma density ne near the introduction window was about 7.4 x 1010 cm-3 and the static axial magnetic field Bz was equal to 875 G. The absorption area was observed to be either “donut” or column shaped. The stream parameters (plasma density ne, electron temperature Ve, floating potential Vf and plasma potential Vp) measured with a Langmuir probe decreased with distance from the source aperture. At a distance of 31 cm, ne was typically 4 x 1010 - 1011 cm-3 with a microwave power 500–800 W. The plasma uniformity was within ±6% over an area 15 cm in diameter and better than ±3% over an area 8 cm in diameter. The effects of the shape of the absorption area and aperture size on the stream characteristics are discussed and used to explain the practical advantages of electron cyclotron resonance sources in thin film technology.