AVS 51st International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS2-MoM

Paper PS2-MoM3
Etch Rate and Profile Evolution Model for High Aspect Ratio Etch in HBr/NF3/O2 Plasma

Monday, November 15, 2004, 9:00 am, Room 213B

Session: Silicon Etching
Presenter: A. Kersch, Infineon Technologies AG, Germany
Authors: A. Kersch, Infineon Technologies AG, Germany
W. Jacobs, Infineon Technologies AG, Germany
W. Sabisch, Infineon Technologies AG, Germany
G. Schulze-Icking, Infineon Technologies AG, Germany
A. Henke, Infineon Technologies AG, Germany
S. Wege, Infineon Technologies AG, Germany
Correspondent: Click to Email
Silicon etching based on a HBr/O2/NF3 plasma generated in a 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 two feature scale models of different complexity. A compact model calculates the etch rate for a given trench geometry by solving an integral equation for the neutral and ion transport inside the trench. Input parameter are ion and fast neutral fluxes and their energy distribution as a function of CCP power, pressure, magnetic field, and the fluxes of reactive radicals as a function of plasma and gas flow conditions. The efficiency of this approach allows the investigation of effects of trench profile on the etch rate for a variety of data. A high level model calculates in addition the trench profile evolution as a function of the above parameters supplemented by the particles angular distribution, a surface scattering distribution, and a chemical rate model for etch and side wall passivation. These calculations are done with an axisymmetric/3D profile simulator (TOPSI3D) which used level set front propagation, Monte Carlo particle transport, and chemical surface reaction rates (1). For the selection of the input parameter, a combination of experimental values (plasma density, V-I measurement, RGA) and reactor scale simulation (plasma, neutral gas flow and collisional sheath) is used. The paper focuses on the effects of power, magnetic field, pressure and gas flow on the etch rate and trench profile. The results of both models are in good agreement with each other as well as with experimental data for several technology nodes. @FootnoteText@ @footnote 1@ W.Jacobs et al, IEDM Tech. Digest, Session 35/5, 2002 .