3D10-250322-11
FOCUS RING(8.5T)

Focus ring 8.5T (OEM P/N 3D10-250322-11), plasma-confining edge consumable for NEST-sourced TEL 300 mm etch systems

2nd-Source new focus ring, 8.5 mm nominal thickness class, for Tokyo Electron (TEL) 300 mm plasma etch chambers

The Focus Ring 8.5T (OEM P/N 3D10-250322-11) is a consumable plasma-confinement ring that sits at the outer perimeter of the electrostatic chuck in a Tokyo Electron (TEL) 300 mm plasma etch process chamber. The “8.5T” designation in the part name refers to the nominal thickness class of the ring, approximately 8.5 mm in the relevant dimension, which is one of the most safety-critical attributes of any focus ring, because that height directly sets where the plasma sheath bends as it crosses the boundary between the silicon wafer and the surrounding hardware.

In a 300 mm etch chamber the focus ring encircles the wafer, bridging the gap between the wafer edge and the grounded or RF-coupled chamber furniture. Its job is to extend the effective electrical and physical surface of the wafer outward, so that the last few millimetres of usable silicon see the same sheath shape, ion energy and ion trajectory as the wafer interior. Without a correctly dimensioned ring in this position, edge dies would etch at a different rate and at a tilted angle, and the outer annulus of the wafer would be lost to the process.

Because the focus ring is directly in the plasma and is bombarded by energetic ions for the whole of its service life, it is a scheduled-replacement consumable. It erodes predictably, its thickness falls over time, and once it thins beyond a control limit the edge process drifts out of specification. Keeping a qualified replacement on the shelf is therefore central to sustaining edge yield and chamber availability.

Functional role of the focus ring in NEST and TEL etch platforms

The focus ring is small in cost relative to the tool, but it exerts an outsized influence on the electrostatics at the wafer edge. In a TEL 300 mm etcher it performs several linked functions simultaneously:

• Extends the plasma sheath beyond the physical wafer edge so that edge dies receive near-centre ion flux and energy, preserving etch-rate uniformity across the full 300 mm diameter.
• Controls the sheath bending angle at the wafer periphery, keeping etched feature profiles vertical at the edge rather than tilted inward or outward.
• Confines the plasma over the wafer surface and limits stray ion attack on the electrostatic chuck and adjacent chamber hardware.
• Provides a sacrificial surface that takes ion bombardment in place of more costly and harder-to-replace components such as the chuck dielectric.
• Participates in the RF return and impedance environment at the wafer edge, influencing local self-bias and coupling.
• Sets a defined, repeatable edge geometry so that process recipes transfer reliably from chamber to chamber and from one ring change to the next.

Material and process performance

Erosion resistance and plasma compatibility

Focus rings for 300 mm etch chambers are produced from process-compatible consumable materials, commonly high-purity silicon, silicon carbide or quartz depending on the chemistry and the chamber position, selected to erode in a clean, predictable manner without shedding metallic contamination into the process. The chosen material must tolerate aggressive fluorocarbon, oxygen and halogen-bearing plasmas while keeping etch by-products volatile so they pump away rather than redepositing on the wafer.

• High purity to avoid introducing mobile-ion or metallic contamination at the wafer edge.
• Stable, slow erosion so that thickness loss is gradual and the edge process drifts in a controllable, predictable way.
• Resistance to thermal shock from RF-driven heating and rapid recipe transitions.

Dimensional and electrical consistency

The 8.5 mm thickness class and the inner and outer diameters that locate the ring around the wafer must be held to tight tolerance, because the sheath responds to fractions of a millimetre. The bulk resistivity and dielectric behaviour of the material must also be matched to the original, since the ring is part of the RF return path and changing its electrical character would shift edge self-bias even if the dimensions were perfect.

• Thickness, flatness and diameter held to the OEM envelope so the starting sheath shape matches the qualified recipe.
• Surface finish controlled to manage erosion rate and minimise particle generation.
• Electrical properties matched to the original so edge self-bias and RF coupling are reproduced.

Impact on tool performance and yield

Because it governs the electrostatics of the outermost wafer annulus, the condition of the focus ring is one of the strongest single levers on edge yield and chamber-to-chamber matching. As it thins, its influence on the process shows up quickly in line-monitor data:

• Edge etch-rate roll-off or roll-up that pushes the outer dies outside the within-wafer uniformity budget.
• Tilted or bowed feature profiles at the wafer edge as the sheath bends over a worn ring surface.
• Loss of usable die in the outer annulus and a shrinking edge-exclusion margin.
• Particle excursions if the ring erodes unevenly, cracks or begins to flake.
• Chamber-matching drift, where two tools running the same recipe diverge because their rings are at different points in their wear life.
• Reduced uptime when an out-of-spec ring forces an unplanned wet-clean and re-qualification.

Common wear and failure modes

Progressive erosion and thinning

The dominant failure mode is normal, expected erosion. Continuous ion bombardment sputters material from the ring, lowering its height and rounding its profile. This is gradual and predictable, which is exactly why focus rings are tracked by RF-hours or wafer count and swapped at a defined wear limit before edge performance falls out of specification.

Cracking and thermal-mechanical fracture

Repeated heating and cooling, combined with mechanical clamping and handling stress, can crack a ring, particularly a silicon or quartz one near end of life when it is thinned and weakened. A cracked ring is an immediate particle and arcing risk and warrants prompt removal rather than continued running.

Particle shedding and surface roughening

As erosion advances, the ring surface roughens and can begin to shed particles or flakes onto the wafer edge, driving defect counts up. Localised redeposition or polymer build-up on the ring can also flake away later, so a ring that looks intact may still be a contamination source once heavily cycled.

Installation and replacement guidance

Focus rings are replaced during scheduled preventive maintenance and must be handled and seated with care, as the ring sets the edge process the moment the chamber returns to production. The following sequence reflects normal good practice; always defer to the site-specific PM procedure for the tool.

• Shut down the chamber, vent to atmosphere and confirm RF and gas isolation according to the tool lockout procedure.
• Remove the worn ring and inspect the electrostatic chuck, the seating surface and adjacent edge hardware for erosion, residue or damage.
• Unpack the new ring with clean, powder-free gloves and inspect it for chips, cracks or transit damage before fitting.
• Clean the seating surface so the new ring beds flat, with no particles trapped underneath that would tilt it or break electrical contact.
• Seat the ring concentrically with the wafer pocket, confirming it is fully home and that the orientation matches the original.
• Close up, pump down, leak-check and run any seasoning or conditioning step required before processing product.
• Reset the ring-life counter and re-qualify edge uniformity and profile on a monitor wafer before releasing the chamber to production.

Spare parts strategy for NEST and TEL etch consumables

Focus rings are high-turnover consumables, so the right sourcing strategy is one that protects uptime without tying up capital in single-source inventory. ESCT Fab Support supplies this ring as a second-source new part with the following advantages:

• Second-source new supply that verifies form, fit and function against OEM P/N 3D10-250322-11 without OEM single-source pricing.
• Dimensional and material control on the critical 8.5 mm thickness class and ring diameters so the starting edge process is reproduced.
• Support for kanban and consignment models that suit a scheduled-replacement consumable.
• A planned lead time of 4-5 weeks, allowing safety stock to be set against PM intervals and ring-life data.
• A single point of contact for the wider family of TEL 300 mm edge consumables, including focus rings, edge rings and silicon electrode parts.

Frequently asked questions

What does the “8.5T” in the part name mean?

It denotes the nominal thickness class of the ring, approximately 8.5 mm in the controlling dimension. Thickness is critical for a focus ring because it sets the starting height of the sheath boundary at the wafer edge, so a ring should always be matched to the thickness class the chamber was qualified with.

Is this an original OEM part?

No. This focus ring is supplied as a second-source new part that is verified to match OEM P/N 3D10-250322-11 for form, fit and function. It is a new, OEM-compatible component and is not an original OEM part.

How often does a focus ring need replacing?

Replacement is driven by erosion, so it is tracked by RF-hours or wafer count rather than a fixed calendar interval. The ring is swapped at a defined wear or thickness limit before edge uniformity and profile drift outside specification; the exact interval depends on the chemistry, power and duty cycle of your process.

What happens if a worn ring is left in service too long?

As the ring thins, the sheath at the wafer edge bends differently, causing edge etch-rate drift, tilted feature profiles, loss of usable edge die and eventually particle excursions or arcing if it cracks. Running past the wear limit erodes yield and risks an unplanned chamber clean.

Does the ring affect chamber matching?

Yes. Two chambers running an identical recipe can diverge if their focus rings are at different points in their wear life, because the edge electrostatics shift as the ring thins. Consistent ring dimensions and synchronised replacement scheduling are important parts of a chamber-matching strategy.

What is the lead time for this part?

The planned lead time is 4-5 weeks. For a high-turnover consumable like a focus ring we recommend aligning safety stock with your PM cadence and ring-life data so a replacement is always available ahead of the next scheduled change.

Summary

The Focus Ring 8.5T (OEM P/N 3D10-250322-11) is a plasma-confinement consumable that surrounds the wafer in a TEL 300 mm etch chamber and governs the electrostatics of the wafer edge. Its 8.5 mm thickness class sets the starting sheath geometry, tying dimensional and material fidelity to edge uniformity, feature profile and chamber matching. As a sacrificial part it erodes predictably and is replaced on a wear-driven schedule. Supplied by ESCT Fab Support as a second-source new ring verified to OEM form, fit and function, with a 4-5 week lead time, it offers a cost-effective, supply-secure alternative for sustaining edge yield and tool availability.

Disclaimer: This part is supplied by ESCT Fab Support as a new, OEM-compatible second-source component, verified to the form, fit and function of Nest part number 3D10-250322-11. It is not an original OEM part and is not sold as one. It is not manufactured by, endorsed by, or affiliated with Nest, and all manufacturer names and part numbers are quoted for identification and compatibility purposes only.

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