5.4 Saturation Region

Step 7: Refine DIBL parameters.

Extracted Parameters Device and Experimental Data Extraction Methodology
ETA0 ETA0 , DSUB DSUB , CDSCD CDSCD Short and long devices Id I_d vs. Vg V_g @ Vd∼Vdd V_d \sim V_{dd} Observe subthreshold region of all devices in the same plot. Optimze ETA0 ETA0 , DSUB DSUB , CDSCD CDSCD .

Note: We do not need very accurate fitting because velocity saturation, smoothing function and output conductance parameters are not determined yet.

Step 8: Extract velocity saturation parameters for long and medium gate lengths.

Extracted Parameters Device and Experimental Data Extraction Methodology
VSAT0 VSAT_0 , VSAT10 VSAT1_0 , PTWG0 PTWG_0 , KSATIV0 KSATIV_0 , MEXP0 MEXP_0 Long and medium devices Id I_d vs. Vg V_g @ Vd∼Vdd V_d \sim V_{dd} Observe strong inversion region Id,sat I_{d,sat} , Gm,sat G_{m,sat} , Id−Vd I_d-V_d .

Note: Long channel alone is not enough to accurately extract velocity saturation parameters.

Step 9: Extract velocity saturation parameters for short and medium gate lengths.

Extracted Parameters Device and Experimental Data Extraction Methodology
AVSAT AVSAT , AVSAT1 AVSAT1 , APTWG APTWG , BVSAT BVSAT , BVSAT1 BVSAT1 , BPTWG BPTWG Short and medium devices Id I_d vs. Vg V_g @ Vd∼Vdd V_d \sim V_{dd} 1. Observe strong inversion region of Id,sat I_{d,sat} and Gm,sat G_{m,sat} . Find VSAT1[Li]=Xi VSAT1[L_i] = X_i , VSAT[Li]=Yi VSAT[L_i] = Y_i , PTWG[Li]=Zi PTWG[L_i] = Z_i to fit data. 2. Extract AVSAT1 AVSAT1 , BVSAT1 BVSAT1 from (Li L_i , Xi X_i ); AVSAT AVSAT , BVSAT BVSAT from (Li L_i , Yi Y_i ); APTWG APTWG , BPTWG BPTWG from (Li L_i , Zi Z_i ).

Step 10: Refine geometry scaling parameters for velocity saturation, over the range from short to long channel devices.

Extracted Parameters Device and Experimental Data Extraction Methodology
AVSAT AVSAT , AVSAT1 AVSAT1 , APTWG APTWG Medium and short devices Id I_d vs. Vg V_g @ Vd∼Vdd V_d \sim V_{dd} Observe strong inversion region of all devices in the same plot. Optimize AVSAT AVSAT , AVSAT1 AVSAT1 , APTWG APTWG .

Step 11: Refine Group 2 scaling parameters.

Further refine the geometry scaling parameters by repeating Step 10 and 7. If not getting good fitting, tune BVSAT BVSAT , BVSAT1 BVSAT1 , BPTWG BPTWG . If still not good, tune other parameters in Group 2 as appropriate. Iteration ends in Step 10 and then proceeds to Step 13. A sample fitting result up till this step is shown in Fig. 18.

Figure 18

Figure 18: Id I_d vs Vg V_g and Gm G_m vs Vg V_g @ Vd∼Vdd V_d \sim V_{dd}

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