DOping profile type location region misc profile specification
The DOPING line places impurities in selected regions of the device. The impurity profiles can be specified by analytic functions, the output of one-dimensional process simulators, one-dimensional tables of depth vs. concentration or from preprocessed (via the BIPAD interface program) output from two-dimensional process simulators.
Gaussian = logical (default is false) LInear = logical (default is false) Uniform = logical (default is false) SUprem3 = logical (default is false) NEW.suprem3 = logical (default is false) Table.1d = logical (default is false) 2d.profile = logical (default is false) BISon = logical (default is false) RELoad = logical (default is false)
GAUSSIAN, LINEAR and UNIFORM are used to analytically describe profile shapes. SUPREM3 is used to get profile information from the original version of the SUPREM-III process modeling program. NEW.SUPREM3 reads data files produced by the more recent release of SUPREM-III, which supports the "export" output file format. TABLE.1D allows for input of tables of concentration versus depth where each line contains a single depth (in um) followed by its associated concentration (in /cm**3). Positive (negative) numbers are used for N (P) doping concentrations, respectively. The device structure and the doping profile must begin at the same co-ordinate, and must have the same orientation. 2D.PROFILE specifies that a general two-dimensional doping profile is to be loaded using the standard BIPAD (or PADRE) file format. BISON also indicates a two-dimensional doping profile is to be loaded but using the special "bison" file format created by BIPAD from BICEPS (version 5.X and predecessors) only. RELOAD specifies the input file will be reloaded from a previously created PADRE doping output file.
location-1D
PARAMETER Uniform Gaussian/Suprem/Table
(x-dir) (y-dir)
----------------- --------- --------- ---------
X.Left = real -infinity SP -infinity
X.Right = real +infinity X.LEFT +infinity
Y.Top = real -infinity -infinity Y.BOT
Y.Bottom = real +infinity +infinity SP
Z.Front = real -infinity -infinity -infinity
Z.Back = real +infinity +infinity +infinity
The box given by the X, Y and Z bounds locates the profile within a device, and defines a volume where the profile is constant (mask edges). Outside this volume, it falls off along the principal axis according to the profile type, and along the lateral axis according to the lateral specifications. The default bounds of the box are chosen depending on the type and principal direction of the profile. In the Gaussian/Suprem case, the bounds default to a plane normal to the principal axis and located at the peak/start of the profile, respectively. This is denoted by the entry SP in the above table.
location-2D
X.Origin = real (default is 0.0) Y.Origin = real (default is 0.0) Z.Front = real (default is min(z) in device) Z.Back = real (default is max(z) in device)
X.ORIGIN and Y.ORIGIN indicate the (x,y) location within the device where the (0,0) point in the 2D doping profile will be located. The doping concentration at points outside the domain of the 2D profile will be determined by the value at the closest x/y edge. Z.FRONT and Z.BACK define the minimum and maximum coordinates in the z-dimension in which the 2D profile is to be placed.
region
REGion = vector
REGION is an optional parameter specifying the region number(s) where doping is to be added. If no region is specified, the entire semiconductor portion of the device is used. In a non-heterostructure mesh (e.g., see the HETERO option on the MESH line), each node may only have one doping value even if it lies on a material interface; in these cases, the determination is made by the hierarchy of nodal material types (semiconductor always outweighs insulator). In heterostructure meshes, a boundary node can have more than one doping concentration, but if the mesh is restored from a file, the RELOAD option is necessary to retain the multiple definition.
misc
INItialize = logical (default is false) COmpensate = logical (default is false) OUTFile = filename ASCII.Out = logical (default is true) NEgate = logical (default is false) ABove = real BElow = real ALl = logical (default is false) Maxdop = real
INITIALIZE reinitializes (zeros) the doping in the device. COMPENSATE specifies that the doping should be added to the net concentration as usual, but subtracted from the total concentration. This option is useful in removing extra doping in a region without raising the total impurity level which would decrease carrier mobility. The OUTFILE option allows the user to save a copy of all the DOPING lines in a file; the file type is specified by the ASCII.OUT parameter. The first DOPING line should have the OUTFILE parameter, so that the doping information on it and all subsequent DOPING lines are saved in that file. The file can be reread after regrid to calculate the doping on the new grid. The NEGATE parameter negates a specified type of doping (N.TYPE, P.TYPE or ALL). The parameters ABOVE and BELOW are options for NEGATE which specify the doping concentration levels above and below which the negate operation will be applied. If specified, MAXDOP defines a maximum absolute limit for the doping concentrations added by this DOPING line; this parameter may be useful for simulating different activation conditions.
profile specification
The manner in which a profile is specified is dependent on the profile type:
specification
COncentration = real N.type/DONor = logical (default is false) P.type/ACceptor = logical (default is false)
CONCENTRATION is the value of the uniform doping level (in atoms/cm**3) and should be positive. The polarity is given by the logical parameters N.TYPE (or DONOR) and P.TYPE (or ACCEPTOR). Doping is introduced in the intersection of the box (see location-1d above) and the selected region(s) (see region above). The default box for a uniform profile is set up to include the entire device area in the specified region(s).
profile
COncentration = real DOSe = real CHaracteristic = real Junction = real SLice.lat = real Z.Slice = real
These parameters define the doping outside of the constant box defined by the location-1d parameters above. CONCENTRATION is the peak concentration, DOSE the total dose, JUNCTION is the location of the junction, and CHARACTERISTIC is either the principal characteristic length for a gaussian profile or the point where the linear profile itself goes to zero. The profile can be specified in three different ways: (1) setting CONCENTRATION and JUNCTION; (2) setting DOSE and CHARACTERISTIC; or (3) setting CONCENTRATION and CHARACTERISTIC. When JUNCTION is used, PADRE by default computes a characteristic length by examining the doping at a point half way between the ends of the constant box and at the given depth; a different lateral position can be used for this computation using SLICE.LATERAL (lateral x or y coordinate) and Z.SLICE (z coordinate).
dopant type is one of:
N.type/DONor = logical (default is false) P.type/ACceptor = logical (default is false)
These parameters define the polarity of the profile.
2D/3D spread
PEak = real (default is 0) DIRection = character (default is "y") Erfc.Lateral = logical RAtio.Lateral = real (default is 0.8) Lat.char = real Z.Char = real (default is LAT.CHAR)
These parameters specify the location of the 1D profile and how it extends in other dimensions. PEAK is the position of the profile peak; the default is placed at the bounds of the constant box (i.e., Y.BOTTOM). DIRECTION is the axis ("x" or "y") along which the profile is directed. By default, the profile in the other ("lateral") dimensions take the same form - e.g., gaussian or linear - as that along the primary axis; ERFC.LATERAL can be used to obtain an error function instead. RATIO.LATERAL gives the ratio of the characteristic length in the lateral dimensions to that defined above. Alternatively, a specific value for this length can be specified using LATERAL.CHAR. Z.CHAR defines a principle characteristic length to be applied in the z-dimension.
If profile type=SUPREM3, NEW.SUPREM3 or ASCII.IN, the following make up the profile specification:
input file
Infile = filename ASCII.IN = logical (default is true)
INFILE gives the name of the input file from which the one-dimensional impurity profile is to be taken, and ASCII.IN specifies whether or not this file is in ascii format.
dopant type is one of:
BOron = logical (default is false) PHosphorus = logical (default is false) ARsenic = logical (default is false) ANtimony = logical (default is false) N.type/DONor = logical (default is false) P.type/ACceptor = logical (default is false)
These parameters indicate the use of a particular dopant species/type. For SUPREM-III files, only the those impurities listed are extracted from the input file, where N.TYPE (or DONOR) and P.TYPE (or ACCEPTOR) refer to all n- and p- type species respectively. For 1d doping tables, the parameters simply define the concentration given in the file (e.g., N-TYPE/DONOR adds the values to the net concentrations and P-TYPE/ACCEPTOR subtracts).
2D/3D spread
DIRection = character (default is "y") STArt = real (default is 0) RAtio.lateral = real (default is 0.8) Z.Char = real
These parameters specify where to locate the one-dimensional profile in the device and how to extend it to the second dimension. DIRECTION is the axis ("x" or "y") along which the profile is directed. START is the depth in the specified direction where the profile should start, and should normally be at the surface. The lateral profile is assumed to have the same form as the principal profile, but shrunk/expanded by the factor RATIO.LATERAL. The defaults for the location box are set up as a line, parallel to the surface, and located at START. Z.CHAR defines a principle characteristic length to be applied in the z-dimension.
If profile type=2D.PROFILE or BISON, the following make up the profile specification:
3d spread
Z.Char = real (default is machine epsilon) Z.2char = real (default is Z.CHAR) Z.Yoff = real Z.Gamma = real (default is 1.0) STRech2d = vector
Z.CHAR defines a principle characteristic length to be applied in the z-dimension. Z.2CHAR is an optional second characteristic length to be used. Z.YOFF defines the y-depth where the breakpoint between characteristic lengths occurs. A tanh smoothing is used between the characteristic length sections, controlled by Z.GAMMA as follows:
such that for larger Z.GAMMA, the grading between Z.CHAR (sigma1) and Z.2CHAR (sigma2) is smoother. STRECH2D = x0, delta-x provides a optional mechanism to expand the profile in the lateral (x) direction, starting at the point x = x0 by an amount delta-x (both in mm).
input file
INFile = filename ASCII.IN = logical (default is true) DIFference = logical (default is false)
INFILE gives the name of the input file from which the one-dimensional impurity profile is to be taken, and ASCII.IN specifies whether or not this file is in ascii format. DIFFERENCE specifies that the 2D profile to be included has been obtained by differencing two other profiles; this parameter is used with process simulator file formats which are written in terms of total and net concentration (instead of acceptor and donor) since these cases permit NA, ND < 0.
A one-dimensional diode with substrate doping 1.0e16/cm**3 and Gaussian profile.
DOP UNIF CONC=1E16 P.TYPE DOP GAUSS CONC=1E20 JUNC=0.85 N.TYPE PEAK=0
An n-channel MOSFET with Gaussian source and drain. Because the default X.RIGHT is +infinity, for the source we must limit the constant part to X.RIGHT=4, and conversely for the drain. Thus the profile has a constant part along the surface, falls off as an error function towards the gate, and as a gaussian in the direction of the bulk. In both cases, the vertical junction is at 1.3 mm.
DOP UNIF CONC=1E16 P.TYPE DOP GAUSS CONC=9E19 N.TYPE + X.RIGHT=4 JUNC=1.3 R.LAT=0.6 ERFC.LAT DOP GAUSS CONC=9E19 N.TYPE + X.LEFT=12 JUNC=1.3 R.LAT=0.6 ERFC.LAT
Read a SUPREM-III bipolar profile and add it to a uniform substrate concentration. Add doping only to those points lying in regions 1 and 2.
COM *** SUBSTRATE *** DOP REGION=1,2 UNIF CONC=1E16 N.TYPE COM *** BASE *** DOP REGION=1,2 SUPREM BORON R.LAT=0.7 INF=sup3.out1 + START=0 COM *** EMITTER *** DOP REGION=1,2 SUPREM PHOS R.LAT=0.8 INF=sup3.out1 + X.LEFT=12.0 X.RIGHT=13.0 START=0
Read a general 2d doping profile and out its origin at (1,0) in the device grid; this profile (A) is loaded as is throughout the entire z-dimension. The second DOPING line loads a second profile (B-A) which is the difference between profile B and A; as a result, for z >= 5um, the device will have profile B. The difference between A and B falls off for z < 5um according to a y-dependent characteristic length; for y << 1um, sigma = 0.25um, whereas for y >> 1um, sigma = 0.5um. Near y = 1um, sigma is determined by the tanh function with a blending coefficient of 0.7.
DOP X.ORIG=1 Y.ORIG=0 2D.PROF INF=sup4.outA DOP X.ORIG=1 Y.ORIG=0 2D.PROF DIFF INF=sup4.outB-A + Z.FRONT=5 Z.CH=0.25 Z.2CH=0.5 Z.YOFF=1 Z.GAM=0.7
Negate the all the n-type doping in the box 0 <= x <= 2.5um and 0 <= y <= 5um.
DOP NEGATE N.TYPE X.L=0 X.R=2.5 Y.TOP=0 Y.BOT=5