AVS 46th International Symposium
    Manufacturing Science and Technology Group Tuesday Sessions
       Session MS-TuA

Paper MS-TuA9
Investigation of Si and SiO@sub 2@ Etch Mechanisms Using an Integrated Surface Kinetics Model@footnote 1@

Tuesday, October 26, 1999, 4:40 pm, Room 611

Session: Interconnect and Integration
Presenter: D. Zhang, University of Illinois, Urbana
Authors: D. Zhang, University of Illinois, Urbana
M.J. Kushner, University of Illinois, Urbana
Correspondent: Click to Email
Computer aided development of new plasma etching processes requires a fully integrated plasma equipment and surface chemistry model to account for the interaction between bulk and surface processes. This is particularly important when different surfaces in the reactor (i.e., wafer, photoresist, walls, window) react differently with plasma generated species. To address these plasma-surface interactions throughout the etch chamber, and their influence on bulk plasma properties, the Surface Kinetics Model (SKM) was developed and integrated into the Hybrid Plasma Equipment Model (HPEM), a 2-D plasma plasma simulation tool. The SKM simulates the surface coverage and reactions of surface residence species using the flux of reactants from the HPEM. Ion energy and passivation layer thickness dependent processes are included. Patterned wafers can be addressed by partitioning the surface sites. The SKM was used to investigate the surface reaction mechanism for the fluorocarbon etching of SiO@sub 2@. The model includes formation of a passivation layer by CF@sub x@ radicals, its etching by F atoms and its sputtering by ions. The SiO@sub 2@ etch process is represented by 3 (or more) steps, which starts with formation of a CF@sub x@-SiO@sub 2@ complex which, with ion-energy activation, desorbs CO@sub x@ or COF@sub x@ products which diffuse back through the passivation. The remaining =SiF@sub x@ surface site is successively passivated by F atoms diffusing through the passivation, until ion activation desorbes the SiF@sub x@. Results will be discussed for C@sub 2@F@sub 6@ etching of SiO@sub 2@ in inductively coupled, rf biased reactors as a function of ICP and bias power, demonstrating the dependence of etch rates and selectivity on passivation layer thickness. @FootnoteText@ @footnote 1@This work was supported by SRC and LAM Research.