Creating a Paper Spice Model Card from nMOS TCAD simulations

mos2ex22.in : Creating a Paper Spice Model Card from nMOS TCAD simulations

Requires: Victory Process / Victory Mesh / Victory Device / UTMOST-IV
Minimum Versions: Victory Process 7.30.4.R / Victory Mesh 1.4.6.R, Victory Device 1.14.1.R / UTMOST-IV 2.8.3.R

This example shows how to generate a paper Spice model card, from a device that has not yet been created, but has only been simulated in TCAD. Once the deckbuild input file has been created, the entire flow can be run, without operator intervention, in the deckbuild environment.

The example flow creates a 3D 65nm nMOS transistor using Victory Process, then simulates unsaturated and saturated threshold voltage curves and an IdVd curve set, using Victory Device. These curves are then used as input to the Spice Model extraction and optimization tool, called UTMOST-IV.

The UTMOST-IV section begins with the go utmost4 line, and the entire script from the script begin line to the script end line is passed to the UTMOST-IV simulator. The run script line then informs UTMOST-IV to run the passed script. Deckbuild will not continue on to the next lines, until the script is completed by UTMOST-IV.

The first few lines begining with var declares variables that will be modified later. This variable declaration is not strictly necessary, but is good practice and is strongly advised.

The next two blocks of the input file load and format the unsaturated and saturated threshold voltage log files generated from the TCAD simulations.

The third block of the input file creates a "for" loop to load in the four IdVd TACD log file curves. The variable "i" is used to index the log file number included at the end of each of the separate TCAD log file base names. Once all these TCAD data quantity names and data formats have been defined, the whole data set is saved using the saveDataSets parameter, which creates the mos2ex22.uds file, which will be used as the curve reference data in the Spice model card optimization routine.

Currently in UTMOST-IV, there is still one project file that needs to be created in the UTMOST-IV interactive GUI, before UTMOST-IV input files can be run in the deckbuild run time environment. This is the mos2ex22.prj file, which has already been created for you, so there is no need to open the UTMOST-IV GUI to run this example. It is envisioned that in a future version of UTMOST-IV, it will be possible to also create this project file within the deckbuild script, allowing complete optimization input files to be created within the deckbuild environment.

The optimization process involves loading a default Spice Model, setting some base device characteristics in the Spice model card, such as gate oxide thickness, length and width etc., that match the TCAD device, defining the device test Spice netlist for running I-V curves, loading the reference TCAD I-V curves for optimization, and then running the optimization routine to modify the Spice model card parameters, such that the generated Spice model then fits the characteristics of the TCAD simulations.

Once the model optimization and extraction is complete, the new Spice model generated curves are compared with the TCAD generated curves, so that the accuracy of the optimization can be visualized. In the generated plots, the filenames containing the letters "ut" are those generated by UTMOST which created the new Spice model card device parameters. The other curves are generated from TCAD simulations.

To load and run this example, select the Load button in DeckBuild > Examples. This will copy the input file and any support files to your current working directory. Select the Run button in DeckBuild to execute the example.