Paramater Data Base (pdb) Commands

Paramater Data Base (pdb) Commands - commands used to control the parameters

Synopsis

The parameter data base allows the user to configure and set various control parameters in major sections of the code. The data base is used for the diffusion, oxidation, and grid sections. There is planned expansion for other sections of the code.

All of the pdb structures are implemented in tcl. FLOOPS accesses parameters with calls back to the tcl parser to obtain values. Consequently, many of the tcl commands can be used to help manage the data base. Scripts can be written to help manage packages of parameters.

The hierarchy section describes the parameter hierarchy in detail. Parameters are stored in a tree like data structure, with leaves being values. Parameters are nested in a consistent way from materials to solution values.

The variables section describes the global variables that are accessible from pdb. These can be helpful in adding to the system. They are also critical in writing parameters that depend on user inputs to commands, for example, temperature.

The commands describe the tcl commands and arguments that compromise the parameter access methodes. They allow general access to set and get operations, as well as bookkeeping operations. Access to the context information is also available.

Description

Parameter Data Base (pdb) Hierarchy

The pdb hierarchy is defined as a tree. Each parameter access command contains a list of keywords that define the location of the parameter in the tree. These are ordered from top down in the parameter list. The first level is material, and cna include interface material names. The second level are solution variables - boron, interstitials, clusters, flow, and oxidant. The next level below are usually parameters themselves. Some dopants have an additional nested level for the defect they diffuse with. Figure 1 illustrates part of the hierarchy.

The "Parameter Names" boxes are the locations in the leaves of the tree. In these locations, the actual name value pairs are stored. For example, the pdb hierarchy {Silicon Boron Interstitial D0} refers to the neutral diffusivity of boron when diffusing with interstitials. The pdb hierarchy {Oxide Flow Viscosity} refers to the low stress viscosity of the oxide. The browser provides an excellent way to explore the hierarchy.

The hierarchy is implemented as a file system for permanent storage. Each level of the heirarchy is a directory until the lowest level where files contain the variable names and values. Each level of the hierarchy can have information tagged on it, and these values are stored in the Info file. The Info files also contain aliases for the names of the underlying levels.

Once read, the hierarchy is stored in tcl using the array features of the language. The top level is stored in the Params variable. Each of that array is a material name and the name of an array variable that stores it values.

Parameter Data Base (pdb) Global Variables

pdbPath
This is the home directory of the pdb directory tree. There should be a directory named Params in this file. The parameter tree and support files should be found here. See the installation directions for further instructions on how to set the default path.

The path can also be a list. If it is a list, directories are searched in order of the list. The first definition of a parameter is used. This allows users (or groups of users) to set up override parameters for local work that are different than the default parameters found in distribution directory.

pdbHeaderFile
This variable is the name of a file that contains header comments to be included in all newly created parameter files. This must be a legal file and be present - its existance is tested for and its absence will create error messages.
Params
This is the global parameter array. It has entries for all the array names for the materials. The top level of the hierarchy is here. For example, the tcl command "set Params(Silicon)" will return the name of the array that the silicon parameters are stored in.
Global
This variable contains the top level context information. It is similar to Params, in that it is a tcl array variable. However, this is where the simulator sets its variables. The first level in this hierarchy is not material, but the process step being performed. These parameters can be accessed with the commands that begin with sim, which indicate that they access the simulator data base, rather than the pdb set.

 

Diffuse Context
The diffusion context contains the parameters set by the diffuse command. The diffuse context can be accessed with any of the names diffuse, Diffuse, diff, and diffusion. The context exports the following information:
temp, tempC, tempK
These three variables hold the current temperature. The first two report in degrees C, and the last in degrees Kelvin.
press, pressure
These atmospheric pressure.
time
The current simulation time in seconds.
ambient
This is a switch variable and can contain either dry, wet, none, or nit.
Etch Context, Deposit Context
Nothing is defined for these contexts currently. In the future, the machine commands will be integrated better into pdb, and various variables are possible.
Implant Context
Nothing is defined for this context currently.

Parameter Data Base (pdb) Commands

In all cases, the attached commands use the {pdb Hierarchy} string as a place holder for the argument list that indicates the position of the parameter. These strings should be replaced with the correct hierarchy. Each of the commands with the {pdb Hierarchy} takes an adjustable number of arguments. They do not take a list and an argument.

Management Commands
pdbClear
This empties the currently stored parameters. New parameter accesses will be forced to re-read the files. This command is useful when testing new parameter values in the file structure to make sure they are entered correctly.
pdbNewMaterial NewMat LikeMat
This command allows new materials to be created. This is used extensively internal to the program. A new material can be made "like" an existing one. This allows the new material to inherit the properties of a known, defined material. New parameters that are set for the new material override stored parameters of the "like" material. This allows most of the properties to be similar.
pdbAliases Mat Aliases
Create aliases for Mat. Aliases can be a list of equivalent names allowed for the material. This allows shorthand names to be created when using the pdb command set. THe aliases are swapped automatically during expansion of the pdb hierarchy.
Parameter Access
pdbSetDouble {pdb Hierarchy} Value
Set a double precision variable in the hierarchy to Value. The pdb Hierarchy should start with a material and work down the tree to a leaf with type double. Value must be a term that can be passed to the expr command and evaluate to a double precision number.
pdbSetBoolean {pdb Hierarchy} Value
Set a boolean variable in the hierarchy to Value. The pdb Hierarchy should start with a material and work down the tree to a leaf with type boolean. Value must be a term that can be passed to the expr command and evaluate to a boolean.
pdbSetFile {pdb Hierarchy} Value
Set a file variable in the hierarchy to Value. The pdb Hierarchy should start with a material and work down the tree to a leaf with type file. Value must be a string that corresponds to a file.
pdbSetSwitch {pdb Hierarchy} Value
Set a switch variable in the hierarchy to Value. The pdb Hierarchy should start with a material and work down the tree to a leaf with type switch. Value must be a string that corresponds to one of the options available in the switch. This is a radio button style entry.
pdbSetString {pdb Hierarchy} Value
Set a string variable in the hierarchy to Value. The pdb Hierarchy should start with a material and work down the tree to a leaf with type string. Value must be a string.
pdbIsAvailable {pdb Hierarchy}
This returns a boolean. If the entry in the hierarchy is defined, the function returns true.
pdbGetDouble {pdb Hierarchy}
Return the double precision value corresponding to the given entry in the hierarchy.
pdbDelayDouble {pdb Hierarchy}
Return the double precision expression corresponding to the given entry in the hierarchy. The expression can be evaluated later - particularly useful for alagator scripts.
pdbGetBoolean {pdb Hierarchy}
Return the boolean value corresponding to the given entry in the hierarchy.
pdbGetFile {pdb Hierarchy}
Return the file name corresponding to the given entry in the hierarchy.
pdbGetSwitch {pdb Hierarchy}
Return the switch value corresponding to the given entry in the hierarchy. This is returned as an integer index into the list of values.
pdbGetString {pdb Hierarchy}
Return the string corresponding to the given entry in the hierarchy.
Context Access
simIsAvailable {Context Hierarchy}
This returns a boolean if the passed Context hierarchy exists. Context hierarchies are always two deep - the first is the simulator context and the second is the name of the parameter.
simGetDouble {Context Hierarchy}
This allows retrieval of a double precision number from the simulation context. Context hierarchies are always two deep - the first is the simulator context and the second is the name of the parameter.
simGetBoolean {Context Hierarchy}
This allows retrieval of a boolean from the simulation context. Context hierarchies are always two deep - the first is the simulator context and the second is the name of the parameter.
simGetFile {Context Hierarchy}
This allows retrieval of a file name from the simulation context. Context hierarchies are always two deep - the first is the simulator context and the second is the name of the parameter.
simGetSwitch {Context Hierarchy}
This allows retrieval of a radio button option from the simulation context. Context hierarchies are always two deep - the first is the simulator context and the second is the name of the parameter.
simGetString {Context Hierarchy}
This allows retrieval of a string from the simulation context. Context hierarchies are always two deep - the first is the simulator context and the second is the name of the parameter.

Examples

pdbGetDouble Silicon Boron Interstitial D0
Return the current value of the boron interstitial neutral diffusivity. This will depend on the last simulated temperature.
pdbSetDouble Silicon Boron D0 {[Arrhenius 1.0 3.6]}
Set the value of the boron interstitial neutral diffusivity. The value will depend on the temperature, using an Arrhenius relationship.
pdbSetDouble Oxide Grid perp.add.dist 0.02e-4
Set the desired grid spacing in oxide to 20nm.
pdbGetSwitch Silicon Boron DiffModel
Return the currently set diffusion model.

Bugs and Missing Features

It would be nice if the switch statement was a little easier to use. You can't set it with an integer, and it will return only integers. It needs two modes.

See Also

Individual commands that use parameters, and tcl.

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