| AVS 55th International Symposium & Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS2-ThM |
| Session: | Plasma Modeling |
| Presenter: | Y. Yang, Iowa State University |
| Authors: | Y. Yang, Iowa State University M.J. Kushner, Iowa State University |
| Correspondent: | Click to Email |
Dual frequency, capacitively coupled plasma (DF-CCP) tools are being developed for etching in microelectronics fabrication with the goal of separately controlling the production of etch precursors and ion energy delivered to the wafer. These tools typically use a high frequency (10s to 100s MHz) to sustain the plasma and a low frequency (a few to 10 MHz) for ion acceleration. With an increase in both the high frequency and wafer size, electromagnetic wave effects (i.e., propagation, constructive and destructive interference) can affect the spatial distribution of power deposition and reactive fluxes to the wafer. These effects are difficult to computationally address due to the coupling between electromagnetic and electrostatic fields, the latter of which is responsible for the formation of the sheath. In this talk, we discuss results from a computational investigation of high frequency effects in DF-CCPs. A 2-dimensional Maxwell equation solver utilizing Finite Difference-Time Domain techniques capable of resolving wave and electrostatic effects in arbitrary geometries was developed and incorporated into the Hybrid Plasma Equipment Model. To capture the high frequency heating, excitation rates are provided by spatially dependent electron energy distributions generated by a Monte Carlo simulation. The method of solution will be discussed and validation will be made by comparison with experiments for single frequency excitation. Experimental trends of the transitioning of the plasma density from flat to edge to center peaked (corresponding to electrostatic, skin depth and wave dominated regimes) with increasing frequency are captured by the model. Results from a parametric investigation of DF-CCPs (LF ≤ 10 MHz, HF ≥ 50 MHz) in polymerizing gas mixtures will also be discussed. Assessments will be made of the changes in power deposition and electron impact ionization profiles as a function of frequency, the location of power coupling and intervening materials.
*Work supported by the Semiconductor Research Corp., Tokyo Electron Ltd. and Applied Materials Inc.