Study on the characteristics of ECR plasma spatial distribution

Abstract

The characteristics of the spatial distribution of electron cyclotron resonance (ECR) plasma in an ECR-plasma enhanced metalorganic chemical vapour deposition system with a divergent magnetic field are investigated by a single Langmuir probe. The results show that the spatial distribution in the resonance room has a significant density gradient in both radial and axial directions. The ECR plasma density attains its highest value, about 3.0 × 1011 cm−3, at a position that moves away from the ECR point in the direction of the microwave window for about 2.5 cm. This peak is about ten times higher than the central plasma density in the downstream of the reactor chamber. Analysis of the spatial distribution in the reactor chamber shows that the ECR plasma in the upper region has poor radial and axial uniformity of plasma density and electron temperature under the influence of the magnetic field, whereas the plasma in the downstream region has fine radial uniformity. This excellent uniformity has extensive application in plasma processing. Furthermore, there is a maximum plasma density and a maximum electron temperature corresponding to a proper magnetic current. A change of magnetic current does not distort the characteristics of spatial distribution in the reactor chamber.