Hydrogen plasma characteristics in a microwave chemical vapor deposition chamber

The state of the plasma plays a crucial role in the progress of the reaction in the deposition chamber and the deposition quality of the carbon material. And the information on plasma electric field distribution, electron number density, electron temperature, and gas temperature is essential to optimize the operation of the MPCVD system. Thus, this paper studied the characteristics of hydrogen plasma in microwave plasma chemical vapor deposition chambers at different conditions. The Multiphysics coupling model of plasma generated by pure hydrogen excitation has been established to calculate the effects of deposition pressure and microwave input power on the main characteristics of hydrogen plasma. As a result of this research, different characteristic quantities have differing sensitivities to process parameters. The electric field strength and electron density are greatly affected by microwave power, while the gas temperature and electron temperature are greatly affected by the deposition pressure. Also, the volume of the plasma ball increases with increasing microwave power and shrinks with increasing deposition pressure; therefore, to increase the power density without changing the plasma ball size, the two parameters must be balanced in tandem. And the temperature results are compared to the experiment, showing a very good correspondence that validates the simplifying assumptions made in the model.