Hybrid Simulation And Experimental Diagnosis Of Capacitively Coupled Plasma In PVD&CVD Process

The plasma-induced physical-vapour deposition (PVD) and physical-vapour deposition (CVD) are the most common methods used for the deposition of thin film materials. Deposition rate of the film and the quality are determined directly by discharge parameters, such as density, ion energy, electric field, etc. Based on the FJL560CI1ultrahigh vacuum magnetron and ion-beam sputtering coating machine and the RF-500CVD coating machine, a hybrid model, including Boltzman Equation, hydrokinetics model and Monte Carlo model, is developed. The model is used to investigate the characteristic of Ar plasma and CH4plasma. Otherwise, Langmuir probe, Faraday probe and Faraday ion energy analyzer plasma diagnostic system are developed to measure the plasma parameters in the two coating machines, and the comparison with simulation result is carried out.The electron energy distribution function (EEDF) in Ar plasma is computed by numerically solving the Boltzmann equation simplified by Lorentz approximation. In a high electric field, the EEDF is observed to be Maxwellian shape, while in a low electric field, a Druyvesteyn-like EEDF is observed, the gas pressure has little effect on the shape of EEDF. In a Townsend discharge, the electron average energy is no more than10eV, and the ionization rate coefficient increases with the increase of electron average energy and the maximum coefficient is in the order of10-14m3s-1. At the pressure of27Pa, the electron transport coefficients (mobility and diffusion) are found to be μe≈107m2V-1s-1and De≈690m2s-1. In an rf discharge, the electron average energy and the ion rate coefficient are similar to the Townsend discharge, and the electron transport coefficients depend strongly on both time and space. The plasma parameters are investigated using a Langmuir probe plasma diagnostic system, and a Maxwellian EEPF is observed, which agrees well with the calculated result of Boltzmann equation. The electron average energy decreases with the increase of rf power or discharge pressure.Parameters of an rf Ar plasma are computed by numerically solving the hydrokinetics model. It is found that, at the cycle of about ωt≈π/2near to the grounded electrode and ωt≈3π/2near to the powered electrode the electric filed is strong, together with high electron average energy and ionization rate coefficient. The electron density varies tempestuously, but a time-stable ion density is found in this region. The plasma density increases and the sheath thickness decreases with the increase of discharge pressure, while both the plasma density and the sheath thickness increase with the increase of rf voltage, and the plasma density decrease and the sheath thickness increases with the increase of self-bias voltage. A Faraday probe plasma diagnostic system is developed to measure the plasma density in the way of ion current density, and the experimental result shows that as the increase of discharge pressure or rf voltage, the plasma density increases, which agrees well with the calculated result of the hydrokinetics model.A hybrid model is developed to investigate the characteristics of energy and angular distributions of the ions impinging on the electrode in an rf capacitively coupled Ar plasma. It shows that the ion energy distribution (IED) is bimodal at high energy field, and the ion angle distribution (IAD) has a significant peak at the small angle region. As the increasing of gas pressure, the IEDs move to the low energy field, the high energy peak disappears and scattering angle of ions increases. The IEDs move to the high energy and the width between the peaks expands with the increase of rf voltage. High ion energy is obtained with the increase of self-bias voltage, and the IEDs move to the high energy field, but the distance between the two peaks changes little. A Faraday ion energy analyzer is developed to measure the IED in Ar plasma, and the experimental result shows a dual-peak IED at low discharge pressure and a single peak IED at high discharge pressure, which agrees well with the simulation result of the MC model.The EEDF in an rf CH4plasma by numerically solving the Boltzmann equation, which is expanded according to the electron reactions in the CH4plasma. EEDF of CH4plasma similar to Ar plasma is found. The transport coefficients are calculated to be μe≈600m2V-1s-1and De≈1300m2s-1at the pressure of18Pa. The hydrokinetics model, which is used in chapter3in Ar plasma, is expanded for CH4plasma according to the electron reactions, ion reactions and also the radical reactions. Characteristics of CH4plasma are calculated with the expanded model and the result shows that the spatiotemporal variations of potential/electric-field and plasma density are similar to an rf Ar plasma. Species of CH3, C2H5, C2H5+and CHs+are the dominant species in CH4plasma, which contribute to the growth of DLC film.