266
Strain-Engineered MOSFETs
where V th0 is the nominal value of threshold voltage, i is the ith value of the
process parameter, a i
n is the process coefficient of the ith process parameter
for the SPICE model parameter and for order n of the polynomial, and P is the
normalised process parameter. Such a normalisation process (P) enables the
encryption of proprietary information like the absolute values of the process
parameters. In our work, we consider the BSIM4 SPICE model parameters as
quadratic functions of process parameters. This model is easily scalable to
higher orders of polynomial (n) for higher accuracy of extraction. The SPICE
model parameter, such as threshold voltage (V th ), involves extraction of nominal SPICE parameters (V th0 ), followed by extraction of process coefficients a i
n
L = 1e–06, W = 1e–06, T = 27
2.0e–04
1.8e–04
1.6e–04
1.4e–04
1.2e–04
1.0e–04
8.2e–05
6.1e–05
4.1e–05
2.0e–05
3.6e–10
0.0 0.1 0.2 0.3 0.4 0.5
VG
VD
ID
0.05
1.00
0.6 0.7 0.8 0.9 1.0
VS = 0.0, VB = 0.0
Current
Max Error: 100
RMS Error: 20.3
Applied
Max Error: 100
RMS Error: 20.3
FIGURE 9.15
Current-voltage characteristics for n-MOSFETs with 45 nm gate length.
TABLE 9.1
Process Parameters under Study and the Corresponding
Allowed Variation
Parameter
Parameter Name % Variation
Gate length
L g
±30%
Gate oxide
G ox
±20%
Halo implant dose
Halo_Dose
±25%
Extension implant dose
Ext_Dose
±10%
Peak temperature for RTA
RTA
±10%