8.14 Sspd_chapter 6_part 7_device simulation2

SSPD_Chapter 6_Part 7_ Device Simulation2_to be continued

7.4. Structure and Electrical Characterization of NPN Transistor.

The input file contains a sequence of statements. Each statement consists of a keyword that identifies the statement and a set of parameters. The general format is:

<STATEMENT><PARAMETER>=<VALUE>

With a few exceptions the input syntax is not case sensitive. One important exception is that commands described in this manual as being executed by DECKBUILD rather than ATLAS are case sensitive. These include: EXTRACT, SET, GO, and SYSTEM. Also, filenames for input and output under UNIX are case sensitive.

For any<STATEMENT>, ATLAS may have our different types for the<VALUE>parameter. These are: Real, Integer, Character, and Logical.

An example of a statement line is:

DOPING UNIFORM N.TYPE CONCENTRATION=1.0e16 REGION=1 OUTFILE=my.dop

The statement is DOPING. All other items are parameters of the DOPING statement. UNIFORM and N.TYPE are logical parameters. Their presence on the line sets their values to true, otherwise they take their default values (usually false). CONCENTRATION is a Real parameter and takes floating point numbers as input values. REGION is an Integer parameter taking only integer numbers as input. OUTFILE is a Character parameter type taking strings as input.

The statement keyword must come first but after this, the order of parameters within a statement is not important.

You only need to use enough letters of any parameter to distinguish it from any other parameter on the same statement. Thus, CONCENTRATION can be shortened to CONC. REGION, but can’t be shortened to R, since there’s a parameter called RATIO associated with the DOPING statement.

Logical parameters can be explicitly set to false by preceding them with the ^ symbol. Any line beginning with a # is ignored. These lines are used as comments.

ATLAS can read up to 256 characters on one line. But it is best to spread long input statements over several lines to make the input file more readable. The \ character at the end of a line indicates continuation.

7.4.1: The Order of ATLAS Commands

The order in which statements occur in an ATLAS input file is important. There are five groups of statements that must occur in the correct order (see Table 7.2). Failure to do so usually causes an error message to appear, which could lead to incorrect operation or termination of the program. For example, if the material parameters or models are set in the wrong order, then they may not be used in the calculations.

The order of statements within the mesh definition, structural definition, and solution groups is also important. Failure to place these statements in proper order may also cause incorrect operation or termination of the program.

Table 7.2. ATLAS Command Group with Primary Statements in each Group.