AVS 45th International Symposium
    Manufacturing Science and Technology Group Tuesday Sessions
       Session MS-TuA

Paper MS-TuA9
TEOS CVD Topography Simulation Using Surface CHEMKIN and EVOLVE

Tuesday, November 3, 1998, 4:40 pm, Room 317

Session: Process, Integration, and Modeling
Presenter: A.H. Labun, Digital Equipment Corporation
Authors: A.H. Labun, Digital Equipment Corporation
T.S. Cale, Rensselaer Polytechnic Institute
P. Ho, Sandia National Laboratories
H.K. Moffat, Sandia National Laboratories
M.E. Coltrin, Sandia National Laboratories
Correspondent: Click to Email
Although the pyrolysis of Si(OC@sub 2@H@sub 5@)@sub 4@ (TEOS) leads to formation of a highly reactive deposition precursor, increasing the residence time in a chemical vapour deposition (CVD) process leads to more, not less, conformal SiO@sub 2@ deposition in high aspect ratio features, contrary to the assumption of a first order deposition reaction commonly used in topography simulation. A newly developed Surface CHEMKIN interface in the EVOLVE 5.0 topography simulator allows EVOLVE to be used in conjunction with CHEMKIN-based reactor codes to explore this and other CVD reaction mechanisms and make process recommendations. Ab initio calculations and experiments lead to consideration of a network of 8 reversible, heterogeneous reactions and 3 reversible, homogeneous reactions, involving 5 surface species and 6 gasses. Under short reactor residence time conditions relatively little TEOS decomposes and it remains the dominant constituent of the bulk gas, but transport limitations cause byproduct gasses to dominate in submicron features. They promote the reverse heterogeneous reactions, slowing the deposition rate inside the features and causing nonconformal films. The sticking coefficients of TEOS and the precursor may vary substantially over the topography and during the deposition. Decomposition of the TEOS under longer reactor residence time conditions leads to similar gas compositions inside and out of the features and hence film deposition in the features becomes conformal.