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The TEL focus ring described here (OEM P/N 2010-251839-11) is a precision-profiled annular consumable that encircles the production wafer inside a Tokyo Electron 300 mm plasma etch chamber. Its raw catalogue designation, “RING, FOCUS SH T3.4-TAPER304”, encodes the geometry: a focus ring of the shadow-style (“SH”) family, machined to a nominal 3.4 mm controlled thickness with a tapered upper profile that extends the plasma sheath outward over the wafer bezel. In service it is the single component that most directly determines whether the outermost few millimetres of every 300 mm wafer etch to the same critical dimensions as the die at the centre.
Mounted concentrically on the lower electrode assembly, immediately surrounding the electrostatic chuck, the focus ring fills the gap between the wafer edge and the chamber’s grounded confinement hardware. Because it sits flush with the wafer surface, the ring becomes an electrical and geometric continuation of the wafer itself, shaping the RF sheath that accelerates ions toward the substrate. The tapered T3.4 profile is engineered so that, when new, the sheath remains vertical right out to the wafer perimeter, preserving anisotropic, perpendicular ion trajectories across the entire usable area.
As a directly plasma-exposed part, the focus ring is a scheduled consumable rather than a permanent assembly. It erodes predictably under continuous ion bombardment, and the rate and uniformity of that erosion govern how many wafers can be processed before edge yield begins to drift. Maintaining a verified supply of dimensionally accurate replacement rings is therefore central to keeping a TEL etch fleet within its critical-dimension and particle specifications.
Within a Tokyo Electron 300 mm etch chamber, the focus ring performs several interrelated jobs simultaneously, all of them tied to controlling plasma behaviour at the most sensitive location on the wafer, its edge.
A focus ring lives in one of the most hostile micro-environments in the fab, continuous exposure to energetic ions, reactive fluorine or chlorine chemistries, elevated surface temperatures and steep electric-field gradients. Both the bulk material and the precision of its machined profile determine how it performs and how long it lasts.
Focus rings for plasma etch are produced from process-matched consumable materials (high-purity silicon, quartz or fine-grain ceramics) selected to erode cleanly without shedding metallic contaminants or generating defect-forming particles. The grade is chosen so its sputter rate and byproduct chemistry suit the specific etch recipe.
The 3.4 mm thickness and tapered upper geometry are not cosmetic, they define the height and slope of the plasma sheath relative to the wafer plane. Tolerances on inner diameter, step height, flatness and taper angle must match the OEM specification, because even small deviations shift the sheath and degrade edge critical-dimension control.
Because the focus ring governs the edge sheath, its condition propagates directly into device yield, especially across the outer ring of die where a worn ring first shows its effect.
A focus ring rarely fails suddenly; instead it wears progressively until edge performance drifts outside specification. Recognising the dominant degradation mechanisms helps engineers set replacement intervals before yield is affected.
Continuous ion bombardment slowly sputters material from the ring’s upper and inner surfaces. As thickness recedes below the nominal 3.4 mm and the taper rounds off, the sheath collapses inward over the wafer edge, tilting ion trajectories and shifting edge critical dimensions, the primary end-of-life signal.
Repeated RF heating and cooling, combined with mechanical clamping stresses, can initiate micro-cracks in brittle ring materials. A cracked ring may shed particles, create localised plasma non-uniformity and, in severe cases, fracture during handling or wafer transfer.
Polymer byproduct buildup and surface roughening alter the ring’s electrical and thermal behaviour and become a reservoir for defect-causing flakes. Roughened or contaminated surfaces also disturb local sheath uniformity, degrading edge etch results before any thickness limit is reached.
Focus ring replacement is a routine preventive-maintenance activity, but because the ring defines edge sheath geometry, cleanliness and correct seating are critical. The following sequence reflects general good practice; always follow the applicable TEL maintenance procedure and your fab’s safety and qualification protocols.
Focus rings are high-turnover consumables, so a disciplined sourcing strategy protects both uptime and yield. ESCT Fab Support supplies this ring as a verified, form-fit-function alternative to the OEM part, giving maintenance teams a dependable second source.
It surrounds the wafer on the lower electrode and extends the plasma sheath beyond the wafer edge. Its tapered T3.4 profile keeps ion trajectories vertical at the perimeter, so edge die etch to the same critical dimensions and profiles as die at the wafer centre.
No. This ring is supplied as a new, second-source, OEM-compatible part. It is verified to match the original to form, fit and function and is cross-referenced to OEM P/N 2010-251839-11, but it is not an original Tokyo Electron branded component.
Replacement is usually scheduled by wafer count or RF hours, then confirmed by inspection. The clearest signals are measurable thickness loss below nominal, a rounded or eroded taper, rising edge defect counts, or a drift in edge critical-dimension and profile uniformity.
Focus rings for plasma etch are made from high-purity, process-matched consumable materials such as silicon, quartz or fine-grain ceramics. The grade is selected to erode cleanly, resist thermal shock and avoid introducing particles or contamination at the wafer edge.
A correctly seated new ring restores the qualified sheath geometry and typically improves edge uniformity that had drifted with wear. As with any consumable change, run qualification wafers and verify edge CD and particle performance before returning the chamber to production.
The current lead time is 4–5 weeks. Because focus rings are consumables with regular replacement intervals, we recommend planning buffer stock around this lead time so preventive maintenance is never delayed waiting on parts.
The TEL tapered T3.4 focus ring (OEM P/N 2010-251839-11, ESCT P/N ES7099-077) is a precision edge-confinement consumable for Tokyo Electron 300 mm plasma etch chambers. By extending and shaping the plasma sheath beyond the wafer edge, it preserves critical-dimension uniformity, profile control and particle performance across the most yield-sensitive region of every wafer. As a wear part, it requires routine replacement with a dimensionally accurate, clean and correctly seated ring. ESCT Fab Support supplies this component as a new, second-source alternative, verified to form, fit and function, with a 4–5 week lead time to support planned maintenance.
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 Tokyo Electron part number 2010-251839-11. It is not an original OEM part and is not sold as one. It is not manufactured by, endorsed by, or affiliated with Tokyo Electron, and all manufacturer names and part numbers are quoted for identification and compatibility purposes only.
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