AVS 53rd International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS2-ThA

Paper PS2-ThA7
Development of High Aspect Ratio, Selective Si Etch Model in CCP Halogen Plasma

Thursday, November 16, 2006, 4:00 pm, Room 2011

Session: Plasma Modeling
Presenter: W. Sabisch, Qimonda AG, Munich, Germany
Authors: D. Fischer, Qimonda AG, Munich, Germany
W. Jacobs, Qimonda AG, Munich, Germany
A. Kersch, Qimonda AG, Munich, Germany
W. Sabisch, Qimonda AG, Munich, Germany
S. Barth, Qimonda AG, Dresden, Germany
A. Henke, Qimonda AG, Dresden, Germany
J. Sobe, Qimonda AG, Munich, Germany
A. Steinbach, Qimonda AG, Dresden, Germany
S. Wege, Qimonda AG, Munich, Germany
M. Reinicke, Dresden University of Technology, Germany
Correspondent: Click to Email
Silicon etching based on a HBr/O@sub 2@/NF@sub 3@ plasma generated in a dual frequency capacitively coupled Merie plasma reactor is used to fabricate DRAM trench capacitors. To maintain a constant capacitance per memory cell an optimum aspect ratio and trench shape with respect to capacitance and cost has to be achieved. In this paper we report about the development of an electrical CCP chamber model as well as a Si etch rate model for high aspect ratio etch selective to an oxide mask. The CCP chamber model is an equivalence circuit model comprising match, chamber impedance from stray capacity and chuck resistivity, plasma sheath and plasma bulk with a resistivity model for electronegative plasma. The parameter values are consistent with a large amount of tool data. The result of the model is a consistent set of electron density, ion current and VDC values for different electronegativities as a function of the tool parameter. In a second step a large set of planar Si and SiO@sub 2@ etch rate data is evaluated with the plasma values to calibrate a plasma and surface reaction model. The selective Si/SiO@sub 2@ etch model is finally combined with an ion- and neutral particle transport model in the trench structure@footnote 1@ to provide etch depths depending on process conditions.@footnote 2@The results of the model are in good agreement with a large amount of data ranging from tool data to trench etch data. @FootnoteText@ @footnote 1@ W. Jacobs et al, IEDM Tech. Digest, Session 35/5, 2002@footnote 2@ A. Kersch et al., AVS 2004, PS2-MoM3.