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    Real-time plasma control in a dual-frequency, confined plasma etcher


    Milosavljević, V. and Ellingboe, A.R. and Gaman, C. and Ringwood, John (2008) Real-time plasma control in a dual-frequency, confined plasma etcher. Journal of Applied Physics, 103 (083302). ISSN 0021-8979

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    Abstract

    The physics issues of developing model-based control of plasma etching are presented. A novel methodology for incorporating real-time model-based control of plasma processing systems is developed. The methodology is developed for control of two dependent variables (ion flux and chemical densities) by two independent controls (27 MHz power and O2 flow). A phenomenological physics model of the nonlinear coupling between the independent controls and the dependent variables of the plasma is presented. By using a design of experiment, the functional dependencies of the response surface are determined. In conjunction with the physical model, the dependencies are used to deconvolve the sensor signals onto the control inputs, allowing compensation of the interaction between control paths. The compensated sensor signals and compensated set–points are then used as inputs to proportional-integral-derivative controllers to adjust radio frequency power and oxygen flow to yield the desired ion flux and chemical density. To illustrate the methodology, model-based real-time control is realized in a commercial semiconductor dielectric etch chamber. The two radio frequency symmetric diode operates with typical commercial fluorocarbon feed-gas mixtures (Ar/O2 /C4F8). Key parameters for dielectric etching are known to include ion flux to the surface and surface flux of oxygen containing species. Control is demonstrated using diagnostics of electrode-surface ion current, and chemical densities of O, O2, and CO measured by optical emission spectrometry and/or mass spectrometry. Using our model-based real-time control, the set-point tracking accuracy to changes in chemical species density and ion flux is enhanced.

    Item Type: Article
    Keywords: Real-time plasma control; dual-frequency; confined plasma etcher;
    Academic Unit: Faculty of Science and Engineering > Electronic Engineering
    Item ID: 6897
    Identification Number: https://doi.org/10.1063/1.2903137
    Depositing User: Professor John Ringwood
    Date Deposited: 20 Jan 2016 17:21
    Journal or Publication Title: Journal of Applied Physics
    Publisher: American Institute of Physics
    Refereed: Yes
    URI:

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