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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).

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.

ProcessPadESD robustnessLeakage
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 180nm5V I/O> 8 kV HBM< 5 nA
TSMC 180nm7V I/O> 2 kV HBM< 50 nA
TowerSemi 350nm4.5V I/O> 8 kV HBM< 100 nA
ProcessPadESD robustnessLeakage
TSMC 130nm 1.0V I/O> 4 kV HBM< 50 pA
TSMC 130nm1.0V rail> 3 kV HBM< 50 pA
TSMC 130nm3.3V I/O> 3 kV HBM< 10 pA
UMC 130nm1.2V I/O> 2 kV HBM< 10 nA
TSMC 90nm1.8V rail> 2 kV HBM< 0.5 nA
TSMC 65nm1.0V I/O> 4 kV HBM< 1 nA
TSMC 65nm1.2V rail> 2 kV HBM< 100 pA
GF 65nm1.0V I/O> 2 kV HBM< 50 nA
GF 65nm1.8V I/O> 3 kV HBM< 100 pA
ProcessPadESD robustnessLeakage
TSMC 40nm 0.9V rail> 2 kV HBM< 100 pA
TSMC 28nm0.85V I/O> 2 kV HBM< 50 pA
TSMC 28nm3.3V I/O> 200 V HBM< 40 pA

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

Foundry provided, standard GPIO library

  • leakage: 100 nA
  • Typical improvement: high Vt devices

Comparable Sofics ESD clamp

  • Leakage: 25 pA
  • 400x lower leakage
ProcessPadESD robustnessLeakage
GF 22FDX1.2V rail > 2 kV HBM< 30 pA
GF 22FDX1.2V I/O > 2 kV HBM< 50 pA
GF 22FDX1.8V rail > 2 kV HBM< 50 pA
GF 22FDX1.8V I/O > 2 kV HBM< 150 pA
GF 22FDX3.3V rail > 5 kV HBM< 10 pA
GF 22FDX3.3V I/O> 2 kV HBM< 500 pA

Blog articles where “low leakage ESD clamps” aspects are discussed.
Blog article “ESD protection for Internet-of-Things
Blog article “Medical applications