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Download TSUPREM-4 Models - Advanced Materials Research Laboratory
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TSUPREM-4 User’s Manual TSUPREM-4 Models In order to consider the fluorine effect, the model FLUORINE as well as the model DEOX must be activated. The following statement enables the FLUORINE model. METHOD MODEL=FLUORINE ENABLE If the model FLUORINE is enabled while the model DEOX is disabled, the diffusion enhancement of boron due to fluorine is ignored even though the diffusion equation for fluorine is solved. Silicide Models TSUPREM-4 allows you to define models for new materials and reactions. This ability has been used to define models for the growth of titanium and tungsten silicides. The following sections describe the kinetics of TiSi2 growth, the specification of the model and parameters, and suggestions for how you can model other silicides. TiSi2 Growth Kinetics Titanium silicide is assumed to form when silicon atoms react in the silicide with titanium at the TiSi2/Ti interface. The consumption of silicon and titanium lead to deformation of the material layers in the structure. Note that while the discussion that follows describes the growth of TiSi2 on silicon, it also applies to growth of TiSi2 on polycrystalline silicon. Reaction at TiSi2/Si Interface At the TiSi2/Si interface you have the reaction Si(Si) → ← Si(TiSi 2 ) + aV(Si) Equation 2-231 Thus silicon (on the Si side of the interface) reacts to form silicon atoms (on the TiSi2 side of the interface) plus some number a of vacancies (on the Si side of the interface). The reaction is reversible, allowing the reformation of silicon (if silicon is released by nitridation of TiSi2, for example). The forward rate of this reaction depends only on temperature, while the reverse rate is also proportional to the concentration of diffusing silicon atoms in the TiSi2. For each silicon atom removed from the silicon side of the interface, the volume of silicon is reduced by MOL.WT ∆V = --------------------------------------------------------6.022 × 10 23 × DENSITY Equation 2-232 where MOL.WT and DENSITY are the molecular weight and density, respectively, of silicon, as specified on the MATERIAL statement. Diffusion of Silicon 2-68 Silicon is transported across the TiSi2 layer by simple diffusion: Confidential and Proprietary Draft 7/21/00 S4 2000.2
