Dissolved oxygen above 100 ppt strongly affects transistors in 2 nm GAA devices. 100 ppt is extremely difficult to achieve.
At the 2 nm node, dissolved oxygen (DO) transitions from a corrosion variable to a functional device contaminant. At atomic-scale dimensions, oxygen directly modifies material interfaces, alters electrical behavior, and drives parametric variability.
Oxygen behaves like an unintended dopant.
Why dissolved oxygen suddenly matters.
At legacy nodes (28 nm and 7 nm), a few parts per billion (ppb) of O₂ primarily influenced reliability and yield through:
- Copper corrosion
- Particle generation
- Minor post-clean oxide regrowth
These effects were manageable with standard UPW degassing in 28 nm and 7 nm nodes.
At 2 nm, structures approach only a few dozen atoms thick. Now the same oxygen levels alter transistor operation itself.
Device-level failure mechanisms at 2 nm:
1) Gate dielectric regrowth
Uncontrolled oxide forms during post-etch rinsing.
- Native SiO₂ grows in seconds
- Even ~0.05 nm oxide growth shifts threshold semiconductor voltages
2) High-k / metal gate degradation
Interfacial chemistry becomes unstable.
- HfO₂ (Hafnium Oxide) interface modification
- Oxidation of TiN, W, and Ru work-function metals
3) Selective deposition failure
Surface termination destroys selectivity.
- Area-selective ALD becomes blanket deposition
- Oxygen-terminated surfaces block reactions
4) Pattern collapse chemistry
Surface energy changes during drying.
- Hydroxylation increases capillary forces
- Critical features deform
5) Contact resistance variability
Metals oxidize almost instantly.
- Co/Ru contacts form insulating layers within seconds
- Increased Rc variation and performance loss
Dissolved oxygen specifications by technology node:
| Technology Node | Typical DO at Point-of-Use | Dominant Impact |
| 28 nm | < 20 ppb | Corrosion |
| 7 nm | < 5 ppb | Oxide regrowth |
| 2 nm | < 100 ppt | Electrical parametric failure |
Leading fabs now target 20–50 ppt O₂ for critical cleans (gate, contact, MOL).
Measuring dissolved oxygen:
Today’s DO measurements are working to catch up with today’s DO requirements. Click here for a 2025 Hach Analytical analysis.
Where control is required inside the fab:
Not all UPW in a fab needs the same purity.
2 nm facilities now operate multi-tier oxygen control architecture.
| Distribution Level | Typical Requirement |
| Main UPW Loop | 0.5 – 1 ppb |
| Critical Sub-Loop | < 200 ppt |
| Tool Point-of-Use | 20 – 100 ppt |
The final tool environment — not the UPW loop — determines transistor variability.
How fabs achieve sub-100 ppt oxygen:
Traditional membrane degassing alone cannot reach 2 nm requirements.
SnowPure is an authorized Liqui-Cel stocking distributor. We sell contactors with X40 and X50 membranes.
Modern systems combine multiple removal mechanisms:
- Membrane degassing with vacuum and high purity nitrogen sweep
- Palladium catalytic hydrogen reduction (O₂ + H₂ → H₂O)
- High-purity polymer piping (metal-free wetted surfaces)
- Headspace-free storage tanks
- High-velocity recirculation (> 1.5 m/s)
- Localized point-of-use deaeration modules
This is no longer water treatment — it is environmental process control.
Key takeaway:
At 2 nm: Dissolved oxygen is no longer a reliability contaminant. It is a device contaminant. TSMC is a leader in 2 nm manufacturing.
UPW systems must therefore be designed with the same philosophy as gas purity and dopant control — because at Angstrom-scale dimensions, chemistry defines circuitry.
Contact SnowPure for more information on low-boron EDI and Dissolved Oxygen control with Liqui-Cel.