Cheng Jia

Two-dimensional simulation of inductively coupled plasma based on COMSOL and comparison with experimental data

A two-dimensional axisymmetric inductively coupled plasma (ICP) model, and its implementation in the COMSOL multiphysical software, is described. The simulations are compared with the experimental results of argon discharge from the gaseous electronics conference RF reference cell in the inductively coupled plasma mode. The general trends of the number density and temperature of electrons with radial scanning are approximately correct. Finally, we discuss the reasons why the comparisons are not in agreement, and then propose an improvement in the assumptions of the Maxwellian electron energy distribution function and reaction rate.

Fluid model of inductively coupled plasma etcher based on COMSOL

Fluid dynamic models are generally appropriate for the investigation of inductively coupled plasmas. A commercial ICP etcher filled with argon plasma is simulated in this study. The simulation is based on a multiphysical software, COMSOL™, which is a partial differential equation solver. Just as with other plasma fluid models, there are drift–diffusion approximations for ions, the quasi-neutrality assumption for electrons movements, reduced Maxwell equations for electromagnetic fields, electron energy equations for electron temperatures and the Navier–Stokes equation for neutral background gas. The two-dimensional distribution of plasma parameters are shown at 200 W of power and 1.33 Pa (10 mTorr) of pressure. Then the profile comparison of the electron number density and temperature with respect to power is illustrated. Finally we believe that there might be some disagreement between the predicted values and the real ones, and the reasons for this difference would be the Maxwellian eedf assumption and the lack of the cross sections of collisions and the reaction rates.

Finite element analysis on factors influencing the clamping force in an electrostatic chuck

As one of the core components of IC manufacturing equipment, the electrostatic chuck (ESC) has been widely applied in semiconductor processing such as etching, PVD and CVD. The clamping force of the ESC is one of the most important technical indicators. A multi-physics simulation software COMSOL is used to analyze the factors influencing the clamping force. The curves between the clamping force and the main parameters such as DC voltage, electrode thickness, electrode radius, dielectric thickness and helium gap are obtained. Moreover, the effects of these factors on the clamping force are investigated by means of orthogonal experiments. The results show that the factors can be ranked in order of voltage, electrode radius, helium gap and dielectric thickness according to their importance, which may offer certain reference for the design of ESCs.

Simulation of cold plasma in a chamber under high- and low-frequency voltage conditions for a capacitively coupled plasma

The characteristics of cold plasma, especially for a dual-frequency capacitively coupled plasma (CCP), play an important role for plasma enhanced chemical vapor deposition, which stimulates further studies using different methods. In this paper, a 2D fluid model was constructed for N2 gas plasma simulations with CFD-ACE+, a commercial multi-physical software package. First, the distributions of electric potential (Epot), electron number density (Ne), N number density (N) and electron temperature (Te) are described under the condition of high frequency (HF), 13.56 MHz, HF voltage, 300 V, and low-frequency (LF) voltage, 0 V, particularly in the sheath. Based on this, the influence of HF on Ne is further discussed under different HF voltages of 200 V, 300 V, 400 V, separately, along with the influence of LF, 0.3 MHz, and various LF voltages of 500 V, 600 V, 700 V. The results show that sheaths of about 3 mm are formed near the two electrodes, in which Epot and Te vary extensively with time and space, while in the plasma bulk Epot changes synchronously with an electric potential of about 70 V and Te varies only in a small range. N is also modulated by the radio frequency, but the relative change in N is small. Ne varies only in the sheath, while in the bulk it is steady at different time steps. So, by comparing Ne in the plasma bulk at the steady state, we can see that Ne will increase when HF voltage increases. Yet, Ne will slightly decrease with the increase of LF voltage. At the same time, the homogeneity will change in both x and y directions. So both HF and LF voltages should be carefully considered in order to obtain a high-density, homogeneous plasma.