TL;DR
Particle excursions are usually a polymer flaking event after missed chamber conditioning, a worn focus ring, or an o-ring shedding particles. Condition the chamber and inspect the focus ring.
What you might see
- particle count on monitor wafers above spec
- particle excursion alarm on in-situ particle monitor
- defect map showing particles at wafer edge
- particle count increasing after plasma clean
Likely causes
Polymer buildup on chamber walls flaking after a thermal or plasma excursion
Worn or cracked focus ring shedding silicon or quartz particles
O-ring degradation from plasma exposure creating elastomer particles
Wafer transfer misalignment causing wafer edge contact with the chamber
Required tools
- Particle monitor wafers
- In-situ particle counter (if available)
- Focus ring replacement
- O-ring kit matched to chamber specifications
- Cleanroom gloves and face shield
Safety first
- Etch chamber walls and focus rings are contaminated with process by-products including potentially toxic fluorine, chlorine, and metal compounds. Wear appropriate chemical PPE when opening the chamber.
- Purge the chamber with dry nitrogen and confirm gas-safe conditions before breaking the chamber.
Procedure
- 1
Run a particle monitor wafer and confirm the count and map before taking any action.
- 2
Run the standard in-situ dry clean plasma clean recipe to remove polymer deposits from the chamber walls.[1]
- 3
Run a condition wafer sequence after the dry clean to re-deposit a controlled polymer layer before running product wafers.[1]
- 4
Inspect the focus ring for cracks, erosion, or chipping. Replace the focus ring if any damage is visible.
- 5
Inspect all chamber o-rings accessible without a full chamber break for swelling, cracking, or discoloration. Replace any degraded o-ring.
- 6
Verify the wafer transfer robot end-effector position. Run the robot calibration routine if the transfer offset is out of spec.
- 7
Run two consecutive particle monitor wafers after conditioning. Accept the chamber only when both wafers are below the particle spec.
Sources
Lam Research Lam Kiyo / Vector / Versys Plasma Etch System general technical documentation, Lam Research
Lam Research plasma etch system general chamber particle management and conditioning procedures (general)
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