Sentaurus Process
6. Working With Advanced Calibration

6.1 Overview
6.2 Activating Advanced Calibration
6.3 Describing the Advanced Calibration File
6.4 Performing Additional Calibration

Objectives

• To demonstrate how to work with Advanced Calibration.

6.1 Overview

Advanced Calibration is a selection of models and parameters, which are recommended by Synopsys to be used for accurate process simulation. It is used as a starting point of process calibration for all silicon-based technologies. In Sentaurus Process, this selection of models and parameters is contained in a text file, which can be opened with any standard text editor. For additional calibration, it is recommended to put all project-specific parameter changes into a separate file, which is sourced after loading the Advanced Calibration defaults.

The files for the Advanced Calibration of Sentaurus Process are located at:

$STROOT/tcad/$STRELEASE/lib/sprocess/TclLib/AdvCal

The file associated with this training material is AdvCal_2017.09.fps.

If you need to fine-tune the parameters of Advanced Calibration, make a local file including additional calibration and source it after initialization of the default Advanced Calibration.

Refer to the Advanced Calibration for Process Simulation User Guide.

6.2 Activating Advanced Calibration

To activate Advanced Calibration of the current release, insert the following command at the beginning of the command file of Sentaurus Process:

AdvancedCalibration

You can specify the release of Advanced Calibration explicitly, for example:

AdvancedCalibration 2017.09

Earlier releases of Advanced Calibration are activated, for example:

AdvancedCalibration 2016.12

Then, you can build the Sentaurus Process process flow with basic processing commands, without specifying parameters and models.

6.3 Describing the Advanced Calibration File

The Advanced Calibration file begins with a set of basic model switches, such as:

pdbSet        Si Dopant     DiffModel    ChargedPair
pdbSet        Si Dopant     ChargeModel  DopantDefect
pdbSet        Si Defect     ChargeModel  Defect

pdbSet        Ge Dopant     DiffModel    ChargedPair

pdbSet        Si Boron      ActiveModel  Transient
pdbSet        Si Indium     ActiveModel  Transient
pdbSet        Si Arsenic    ActiveModel  Transient
pdbSet        Si Phosphorus ActiveModel  Transient
pdbSet        Si Antimony   ActiveModel  Transient
pdbSet        Si Germanium  ActiveModel  None
pdbSet        Si Carbon     ActiveModel  NeutralCluster

pdbSet        Ge Boron      ActiveModel  Transient
pdbSet        Ge Arsenic    ActiveModel  Transient

<other model settings>

The second part of the Advanced Calibration file contains the parameters for the diffusion and reaction equations, which are set at the beginning of the process simulation and remain valid for all process steps, such as:

pdbSet            Si Int Cstar {[Arr 3.12e23 2.932]}
pdbSetDouble      Si Int Di    {[Arr 51.0     1.77]}

pdbSetDoubleArray Si Int D     { -1 {[pdbGetDouble Si Int Di]}
                                  0 {[pdbGetDouble Si Int Di]}
                                  1 {[pdbGetDouble Si Int Di]}
                                  2 {[pdbGetDouble Si Int Di]} }

pdbSetDoubleArray Si Int ChargeStates { -1 {[Arr 6.0   0.52]}
                                         0       1.0
                                         1 {[Arr 1.68  0.0655]}
                                         2 {[Arr 0.001 0.0655]} }

<other parameter settings>

Process condition–dependent changes, such as the initial conditions after ion implantation, are facilitated by Sentaurus Process callback procedures. Section 5. Working With Custom Calibration Files provides a simple application of these callback procedures.

The model used to calculate point defects can be selected with the defect.model argument. Its options are plus.one (default), effective.plus.n, frenkel.pair, and user.defined.

The value can be set directly in the implant command:

implant Boron energy=50 dose=2e13 defect.model=user.defined

or globally, for any implantation step, in the PDB Browser:

pdbSet ImplantData defect.model user.defined

When user.defined is selected, Sentaurus Process assumes that the point defects are updated by the UserPointDefectModel procedure, which is defined in section 3.5 of AdvCal_2017.09.fps.

UserPointDefectModel calls other procedures such as impPostProcess_AdvCal, which is introduced for all data-field postprocessing. In particular, the scaling factors for point defects and damage are set, such as:

fproc impPostProcess_AdvCal { Species Name Energy Dose Model IFac VFac CDose\
 {Suffix ""} } {

        if { [expr $IFac >= 0.0] } {
            set ifactor $IFac
        } else {
            if { [info procs ifactor_${mat}_${Species}] != "" } {
                set ifactor [ifactor_${mat}_${Species} $Energy $Dose]
            } elseif { [info procs ifactor_$Species ] != "" } {
	        set ifactor [ifactor_$Species $Energy $Dose] 
            } else {
	        set ifactor 1.0
            }
        }

The ifactor, vfactor, dfactor, aminit, and acinit can be defined per species in procedures, such as:

fproc ifactor_Arsenic { Energy Dose } {
return [expr 1.0 +\
 8.0*$Dose/($Dose+1.0e14)*$Energy*$Energy/($Energy*$Energy+4.0)]
}

The command fproc defines a Tcl procedure in the same way as the proc command. The advantage of using fproc is that the procedure is saved and restored in TDR files, which guarantees exact restarting.

6.4 Performing Additional Calibration

For the process simulation of any new technology or technology node, you should use Advanced Calibration as the starting point. In many cases, it will give accurate results without requiring additional fine-tuning.

However, as previously mentioned, if additional fine-tuning is needed for customized calibration, you should create a local user calibration file user_calibration.fps, including only the model and parameter changes compared to the default Advanced Calibration. This file should be sourced after the initialization of Advanced Calibration:

AdvancedCalibration 2017.09
source user_calibration.fps