6 Local Parameter Extraction for CV-IV

This procedure shows how to extract parameters for I-V and C-V fittings for device with a particular channel length. The procedure can be followed for both long and short channel devices for local fitting. In the future we plan to expand this section to include the global parameter extraction for the C-V part, as done for the I-V part in the previous section.

The complete CV-IV fitting procedure consists of 7 steps. The procedure starts with fitting $C_{gg}-V_{gs}$ data at low $V_{ds}$ (50mV) to extract $PHIG$ , $NSUB$ , $EOT$ and quantum mechanical effects related parameters. These parameters are used to fit I-V data at low $V_{ds}$ (50mV) to extract subthreshold I-V and mobility related parameters. The extracted parameters are utilized to fit the I-V data at high $V_{ds}$ (1V), to extract parameters related to $V_{th}$ shift due to DIBL, $V_{ds}$ dependence of subthreshold slope, and velocity saturation. In the next step, $I_{ds}-V_{ds}$ data at various $V_{gs}$ are fitted to extract parameters related to DIBL, output conductance and CLM.

Since the saturation parameters are already extracted in Step 3, we can use $C_{gg}-V_{gs}$ data at high $V_{ds}$ (1V) to extract parameters related to CLM for the C-V part. All 7 steps are summarized in the following table with description of the data used, bias conditions and list of extracted parameters with which part of data they affect.

Figure 21: Fitting results from a self-consistent IV-CV extraction.

CV-IV procedure applicable for devices with any channel length

Step	Data Used	Bias	Parameters Extracted (Quantities Influenced)
0	-	-	Initialize process and model control parameters such as $DEVTYPE$ , $HFIN$ , $TFIN$ , $FPITCH$ , $NFIN$ , $NF$ , $ASEO$ , $ADEO$ , $L$ , $XL$ , $LINT$ , $DLC$ , $GEOMOD$ etc.
1	$C_{gg}-V_{gs}$	$V_{ds}$ = 50 mV	$PHIG$ ( $V_{fb} = V_{th}$ ), $NSUB$ (steepens C-V slope), $EOT$ , $QMTCENCV$ (capacitance value at high $V_{gs}$ ), $QM0$ , $ETAQM$ , $ALPHAQM$ (lowers slope steepness), $CFS$ , $CFD$ (parasitic capacitance parameters as needed)
2	$I_{ds}-V_{gs}$ , $g_m$	$V_{ds}$ = 50 mV	$CDSC$ (subthreshold slope), $CS$ (subthreshold $I_{ds}$ ), $U0$ (low field mobility), $MUE$ (mobility at moderate $V_{gs}$ ), $THETMU$ (mobility at high $V_{gs}$ ), $ETAMOB$ (sharpness of $g_m$ curve)
3	$I_{ds}-V_{gs}$ , $g_m$	$V_{ds}$ = 1 V	$CDSCD$ ( $V_{ds}$ dependence of subthreshold slope), $ETA0$ , $DSUB$ ( $V_{th}$ shift due to DIBL at high $V_{ds}$ ), $VSAT$ , $KSATIV$ ( $I_{ds}$ , $g_m$ at moderate $V_{gs}$ ), $VSAT1$ (saturation current at high $V_{gs}$ ), $PTWG$ ( $g_m$ at high $V_{gs}$ )
4	$I_{ds}-V_{ds}$ , $g_{ds}$	Various $V_{gs}$ (0-1 V)	$PCLMG$ , $PCLM$ ( $I_{ds}$ , $g_{ds}$ at high $V_{ds}$ ), $MEXP$ , $VSAT1$ (optimize by looping between Step 3 and 4)
5	$C_{gg}-V_{gs}$	$V_{ds}$ = 1 V	$PCLMCV$ ( $C_{gg}$ value at high $V_{gs}$ ), $PCLMGCV$ ( $C_{gg}$ curvature at high $V_{gs}$ )
6	$C_{sg}-V_{gs}$	$V_{ds}$ = 50 mV	Step 1 ensures good fit of $C_{sg}$ at low $V_{ds}$
7	$C_{sg}-V_{gs}$	$V_{ds}$ = 50 mV	Under investigation.

6 Local Parameter Extraction for CV-IV

6 Local Parameter Extraction for CV-IV

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