Table 1.
Structural parameters used in simulation *As per ITRS dimensions (Wikipedia 14nm process, 2020).
| Simulation work | ||
|---|---|---|
| Device’s performance parameters | (n-FinFET) | (p-FinFET) |
| Gate length, Lg (nm) | 14 | 14 |
| Transistor fin pitch (nm) | 42 | 42 |
| Transistor fin width, WFin (nm) | 8 | 8 |
| Transistor fin height, HFin (nm) | 24 | 24 |
| Workfunction, WF (eV) | 4.6 | 4.6 |
| Gate dielectric permittivity, k | 40 | 40 |
| Physical oxide thickness (nm) | 1.1 | 1.1 |
| Supply voltage, Vd (volts) | 0.75 | 0.75 |
Table 2.
Important TCAD device parameters for an inverter design.
| Process parameters | Value |
|---|---|
| Design rule unit lambda (µm) | 0.007 |
| Thickness of substrate region (µm) | 0.03 |
| Height of fin (µm) | 0.024 |
| Thickness of gate oxide (µm) | 0.0011 |
| S/D doping concentration (donor) for nMOS (cm-3) | 3E20 |
| S/D doping concentration (acceptor) for pMOS (cm−3) | 3E20 |
| Supply voltage, Vd (V) | 0.8 V |
| Thickness of buried oxide (µm) | 0.02 |
| Thickness of poly-silicon gate (µm) | 0.002 |
| Thickness of ILD dielectric (µm) | 0.008 |
| Thickness of ILD Metal 1(µm) | 0.008 |
| Lateral characteristic length of S/D doping of nMOS (µm) | 0.004 |
| Vertical characteristic length of S/D doping of nMOS (µm) | 0.003 |
| Doping concentration in p-type substrate (cm−3) | 1E16 |
| Doping concentration in body (cm−3) | 1E17 |
Figure 1:
Bird eye view of SOI n-FinFET: (A) 3D structure of SOI n-FinFET, (B) Side view of device having composite high-k gate dielectric, (C) Layout of n-FINFET device.
Figure 2:
Id-Vg characteristics of FINFET with reference (de Andrade et al., 2011) and simulation.
Figure 3:
Variation of electrostatic surface potential along the channel length for k = 40, high-k gate dielectric constant.
Figure 4:
Flowchart of the simulation procedure involved in visual TCAD.
Table 3.
Impacts of gate dielectric SiO2 and LaZrO2 on the performance of n-FinFET device.
| Simulated n-FinFET | ||
|---|---|---|
| Parameters (Vd = 0.75 V, Vg = 0.75 V) | Gate dielectric (LaZrO2) k = 40 | Gate dielectric (SiO2) k = 3.9 |
| ION (A) | 4.95 × 10−5 | 1.78 × 10−5 |
| IOFF(A) | 3.61 × 10−14 | 5.02E × 10−13 |
| ION/IOFF | 1.37 × 109 | 3.50 × 107 |
| Vt (V) | 0.253 | 0.207 |
| SS(mV/dec) | 60.3 | 67.02 |
| DIBL(mV/V) | 10.1 | 43 |
| gm (S) (at Vg = 50 mV) | 2.42 × 10−4 | 2.69 × 10−5 |
| VEA (V) (at Vg = 50 mV) | 10.7 | 0.88 |
| TGF (V−1) (at Vg = 50 mV) | 24.55 | 23.2266 |
| gd (S) (at Vg = 50 mV) | 1.8 × 10−15 | 1.95 × 10−12 |
| AV (dB) (at Vg = 50 mV) | 183 | 139.7 |
Figure 5:
Transfer characteristics of n-FinFET in log and linear scale for Lg = 14 nm, Vg = 0 to 0.75 V and Vd = 0.75 V.
Table 4.
Performance analysis of FinFET devices.
| n-FinFET | p-FinFET | |||
|---|---|---|---|---|
| Metrics | Lin (Vd = 50 mV) | Sat (Vd = 0.75 V) | Lin (Vd = 50 mV) | Sat (Vd = 0.75 V) |
| ION (A) | 1.37 × 10−5 | 4.95 × 10−5 | 1.81 × 10−5 | 4.54 × 10−5 |
| IOFF(A) | 2.64 × 10−14 | 3.61 × 10−14 | 2.69 × 10−14 | 3.98 × 10−14 |
| ION/IOFF | 0.51 × 109 | 1.37 × 109 | 0.67 × 109 | 1.14 × 109 |
| SS (mV/dec) | 59.9 | 60.3 | 59.9 | 60.9 |
| Vt (V) | 0.261 | 0.253 | 0.262 | 0.253 |
| gm (S) | 5.88 × 10−5 | 2.42 × 10−4 | 4.71 × 10−5 | 2.33 × 10−4 |
| TGF (V−1) | 24.68 | 24.55 | 24.65 | 24.37 |
| DIBL (mV/V) | 10.1 | 12.3 | ||
Figure 6:
Simulated transfer characteristic of n-FinFET and p-FinFET devices.
Figure 7:
Output characteristics of n-FinFET and p-FinFET devices for same dimensions: Lg = 14 nm, HFIN = 24 nm, WFIN = 8 nm, Tox = 1.1 nm, WF (N) = 4.6 eV, and k = 40.
Figure 8:
Schematic layout of optimized FinFET-based inverter circuit with dimensions (HFin = 24 nm, Tox = 1.1 nm, k = 40 and WF = 4.6 eV).
Figure 9:
Butterfly curve for proposed FinFET-based inverter (n-FinFET and p-FinFET of equal size) at 0.8 and 0.4 V supply voltage.
Table 5.
Impact on noise margin due to temperature and voltage variation for simulated inverter circuit
| Temperature (kelvin) | Voltage (volts) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gate dielectric permittivity value(k) | 273 K | 300 K | 398 K | 0.4 V | 0.8 V | 1.2 V | ||||||
| NMH (V) | NML (V) | NMH (V) | NML (V) | NMH (V) | NML (V) | NMH (V) | NML (V) | NMH (V) | NML (V) | NMH (V) | NML (V) | |
| 40(LaZrO2) | 0.4 | 0.377 | 0.375 | 0.375 | 0.35 | 0.35 | 0.195 | 0.12 | 0.375 | 0.375 | 0.55 | 0.55 |