Low leakage

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ESD clamps with low leakage

Sofics technology has been applied for many different applications. A number of applications require ESD solutions with (much) lower leakage compared to the conventional ESD clamps.
For instance, in IoT or medical circuits designers want to reduce total power consumption. In wireless applications, lower leakage improves the Q-factor for LNA circuits. Some high-impedance sensor interfaces need (ultra-low) leakage to ensure the bias levels are not affected.
Sofics ESD cells have orders of magnitude lower leakage (nano-Amps instead of micro-amps).
ESD-low-leakage

Examples in different processes

Examples for different process nodes are shown below. This is just a subset of cells proven on silicon and in mass production.

All cells can be ported to other processes. The actual numbers (ESD robustness, leakage, capacitance, area) may vary slightly, also depending on the circuit to be protected, process, voltage level.

Mature CMOS (0.5um to 180nm)

Process Pad ESD robustness Leakage
TSMC 180nm 1.8V rail >5 kV HBM <200 pA
TSMC 180nm 1.8V I/O >5 kV HBM <200 pA
TSMC 180nm 5V rail > 8 kV HBM < 5 nA
TSMC 180nm 5V I/O > 8 kV HBM < 5 nA
TSMC 180nm 7V I/O > 2 kV HBM < 50 nA
TowerSemi 350nm 4.5V rail > 8 kV HBM < 100 pA

Mainstream CMOS (130nm to 65nm)

Process pad ESD robustness Leakage
TSMC 130nm 1.0V I/O > 4 kV HBM < 50 pA
TSMC 130nm 1.0V rail > 3 kV HBM < 50 pA
TSMC 130nm 3.3V I/O > 3 kV HBM < 10 pA
UMC 130nm 1.2V I/O > 2 kV HBM < 10 nA
TSMC 90nm 1.8V rail > 2kV HBM < 0.5 nA
TSMC 65nm 1.0V I/O > 4 kV HBM < 1 nA
TSMC 65nm 1.2V rail > 2 kV HBM < 100 pA
GF 65nm 1.0V I/O > 2 kV HBM < 50 nA
GF 65nm 1.8V I/O > 3 kV HBM < 100 pA

Advanced CMOS (40nm to 22nm)

Process Pad ESD robustness Leakage
TSMC 40nm 0.9V rail > 2 kV HBM < 100 pA
TSMC 28nm 0.85V I/O > 2 kV HBM < 50 pA
TSMC 28nm 3.3V I/O > 200 V HBM < 40 pA

Comparing the foundry ESD solution to the Sofics approach on a 40nm CMOS process

SOI technology

Process Pad ESD robustness Leakage
GF 22FDX 1.2V rail > 2 kV HBM < 30 pA
GF 22FDX 1.2V I/O > 2 kV HBM < 50 pA
GF 22FDX 1.8V rail > 2 kV HBM < 50 pA
GF 22FDX 1.8V I/O > 2 kV HBM < 150 pA
GF 22FDX 3.3V rail > 5 kV HBM < 10 pA
GF 22FDX 3.3V I/O > 2 kV HBM < 500 pA

FinFET & FDSOI technology

BiCMOS technology

Process Pad ESD robustness Parasitic capacitance
TSMC 130nm 1.2V I/O > 4 kV HBM < 100 fF
TSMC 130nm 1.2V I/O OVT > 2 kV HBM < 50 fF
UMC 130nm 1.2V I/O > 2 kV HBM < 150 fF
TSMC 90nm 3.3V I/O > 2kV HBM < 100 fF
TSMC 65nm 1.8V I/O > 4 kV HBM < 100 fF
TSMC 65nm 1.0V I/O > 3 kV HBM < 70 fF
GF 65nm 1.2V I/O > 2 kV HBM < 50 fF
GF 65nm 3.3V I/O > 2 kV HBM < 50 fF

Customer quotes

Further reading

Blog articles where “low leakage ESD clamps” aspects are discussed.

Blog article “ESD protection for Internet-of-Things

Blog article “Medical applications