A good initial guess can be very helpful in getting a solution in a reasonable amount of time. Values may be based on a previous simulation, experimental information, or educated guesses. If species or site fractions do not sum to 1.0, the LPCVD Furnace Model will normalize them.
Table 4.8: SPECIFY THE GUESS Keyword Phrases
|
Keyword Phrase |
Description |
|---|---|
|
SPECIFY THE GUESS FOR GAS MOLE FRACTIONS |
Title of optional keyword sub-block that gives an initial guess for the gas composition. Part of the DEFINE A MODEL or CHANGE THE MODEL keyword blocks. Requires END statement to close keyword sub-block. Example: SPECIFY THE GUESS FOR GAS MOLE FRACTIONS |
|
(gas species name) = |
Provides the initial mole fraction for a specific gas phase species. This keyword phrase is repeated for each chemical species in the system. Unspecified gases are assumed to have zero mole fraction. Part of the SPECIFY THE GUESS FOR GAS MOLE FRACTIONS keyword sub-block. Example: SIH4 = 0.7 Units: Mole fraction Default: Equal for all gas-phase species. |
|
SPECIFY THE GUESS FOR SURFACE (site name) SITE FRACTIONS |
Title of optional keyword sub-block that gives an initial guess for the surface coverages. Sub-block should be repeated for each type of site for each type of surface in the mechanism. Part of the DEFINE A MODEL or CHANGE THE MODEL keyword blocks. Requires END statement to close keyword sub-block. Example: SPECIFY THE GUESS FOR SURFACE SILICON SITE FRACTIONS |
|
(site species name) = |
Provides the initial site fraction for a specific surface species for a specific site. This keyword phrase is repeated for each surface species that can occupy this site. Unspecified species are assumed to have zero mole fraction. Part of the SPECIFY THE GUESS FOR SURFACE (site name) SITE FRACTIONS keyword sub-block. Example: SIH(S) = 0.5 Units: Site fraction Default: Equal for all surface species in the specified site phase. |