| AVS 54th International Symposium | |
| Plasma Science and Technology | Monday Sessions |
| Session PS1-MoM |
| Session: | Plasma Modeling |
| Presenter: | V. Le, University of California at Los Angeles |
| Authors: | C.C. Hsu, University of California at Los Angeles V. Le, University of California at Los Angeles J.P. Chang, University of California at Los Angeles |
| Correspondent: | Click to Email |
The ion flux spatial profile and the etching by-products transportation are among the most important characteristics for plasma processes. The above characteristics need to be well-tailored in order to achieve the desired etching process performance, such as the uniformity and the etched feature profile. A numerical model has been developed to investigate how the processing parameters affect the plasma characteristics and how these characteristics in turn alter the spatial distribution of the plasma species. This numerical model is a two dimensional fluid model of an inductively coupled plasma in mixtures of chlorine, oxygen, and argon. It has been setup to resemble a simplified commercial etching tool, AMAT DPS-IITM, used for 300 mm wafer shallow trench isolation (STI) processes. This tool is equipped with dual-coil and dual-flow arrangements allowing for additional etching process control. It was shown in this model that the spatial profile of the inductively coupled power deposition can be altered by changing the current ratio of the outer and the inner coils of the dual-coil (DC ratio). This change in turn altered the spatial profile of the ion flux and the plasma species densities. For example, by increasing the DC ratio, the center-to-edge ratio of the Cl radical and the ion flux to the wafer surface decreased. The model was then used to interpret the spatial variation and the variation among different operating conditions of a number of STI etched feature profiles obtained by an AMAT DPS-IITM with chlorine-based chemistries. The model qualitatively explained the spatial variation of the etched depth and the side wall angles of the etched profiles. One example was to explain the consistently positive center-to-edge variation of the etched profile sidewall angel using the center-high by-products density obtained by this fluid model. The effect of the flow to the dual-flow gas feed on the by-products transportation and distribution will also be discussed.