Numerical investigation of a low-electron-temperature ECR plasma in Ar/N₂ mixtures

In general, electron temperature is an important plasma parameter which has much influence in the film property. In this paper, the mechanism for decreasing the electron temperature in an electron cyclotron resonance plasma is numerically investigated using a fluid model. A mixture of argon and nitrogen is used as the working gas under the assumption of plasma nitridation. The simulation was carried out with typical magnetic field configurations and various mixture ratios. As a result, it was found that the application of magnetic mirror was suitable for the production of a low-electron-temperature plasma. Besides, the calculation results indicated that the addition of nitrogen was effective to decrease the electron temperature approximately 2 eV due to the vibrational excitation of nitrogen molecules by electron impact.