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The TEL Focus Ring (OEM P/N 3D10-250576-21, ESCT P/N ES7099-070) is a plasma-facing consumable that sits in the outermost annular position of the lower electrode assembly in Tokyo Electron 300 mm plasma etch chambers. It encircles the wafer and extends the electrically active surface beyond the wafer edge, presenting a continuous, predictable boundary to the plasma sheath so that the discharge does not “see” an abrupt material and potential discontinuity right where the device-critical edge dice sit.
In a wafer-edge environment governed by sheath shape, RF return current and ion trajectory, the focus ring is the component that decides whether the last few millimetres of the wafer etch like the centre or drift out of specification. Its designation, here abbreviated in the catalogue as “8/MIN/CL”, ties it to a specific chamber and clamp configuration within the TEL platform, and its profile, diameter and material grade are matched to a defined recipe window rather than being a generic ring.
Because it is consumed by the same energetic ions and reactive radicals that do the etching, the focus ring is a scheduled-replacement item. As it erodes, the sheath geometry it supports changes, and edge yield follows. Understanding what this ring does, and replacing it before it drifts out of its useful band, is central to keeping a TEL etch chamber producing wafers within edge specification.
The focus ring is not a passive spacer. It is an electrically and geometrically engineered surface that conditions the plasma sheath at the wafer perimeter and forms part of the RF current path through the chuck. In a TEL 300 mm etch chamber it performs several interlocking functions:
Focus rings of this class are produced from high-purity plasma-grade materials, commonly silicon, quartz or silicon carbide depending on chamber and recipe, selected for erosion resistance, low particle generation and chemical compatibility with the etch chemistry. The grade and surface finish are matched to the TEL process window so that the ring erodes predictably rather than catastrophically.
The plasma-facing surface must withstand sustained ion bombardment and reactive-radical attack while contributing as few particles and as little metallic or organic contamination as possible. Purity and a controlled microstructure determine both how slowly the ring recedes and how cleanly it does so.
A focus ring only does its job if its inner diameter, step height, flatness and concentricity match the design intent. Small deviations in the gap between ring and wafer, or in ring height relative to the wafer plane, translate directly into sheath distortion and edge non-uniformity.
The focus ring exerts an outsized influence on the wafer edge, the region where modern devices are densest and yield is most fragile. A ring that is correct and fresh supports tight edge uniformity; a worn or wrong ring quietly costs die at the perimeter long before it triggers a hard alarm.
As a sacrificial plasma-facing consumable, this focus ring fails progressively rather than suddenly. Recognising the dominant wear mechanisms lets process engineers set sensible replacement intervals and avoid the slow yield bleed that a tired ring causes.
Continuous ion bombardment thins the ring over time. As its height drops below the wafer plane, the sheath bends inward at the edge, tilting ions and shifting edge critical dimension and etch rate, the classic end-of-life signature that defines the ring’s usable lifetime.
Localised attack, thermal cycling and redeposition roughen the surface and can seed micro-cracks. These features shed particles onto the wafer, raising defectivity, and in severe cases can propagate into chips or fractures that contaminate the chamber.
A ring that is not seated flat, or that is installed with fingerprint or particulate contamination, distorts the local electrical and thermal boundary and can arc or generate defects. Chipped edges from rough handling shorten life and compromise the sheath geometry from the first wafer.
Replacement is a routine preventive-maintenance task, but because the ring sets the edge boundary condition it must be handled and seated with care. Always follow the applicable TEL maintenance procedure and site safety practices; the sequence below is a general guide.
Focus rings are scheduled consumables, so availability and consistency matter as much as the part itself. ESCT Fab Support stocks and sources TEL-compatible etch consumables to keep PM cycles on schedule without tying up capital in oversized inventory.
It surrounds the wafer on the lower electrode and extends the plasma sheath past the wafer edge, keeping ion trajectories vertical at the perimeter. This preserves edge etch-rate and critical-dimension uniformity and protects the chuck periphery from direct ion bombardment.
No. It is supplied as a 2nd Source NEW, OEM-compatible focus ring verified to the form, fit and function of TEL OEM P/N 3D10-250576-21. It is not an original OEM part and is not sold as one.
End of life shows up as edge erosion and height loss that shift edge critical dimension, etch rate and profile, often alongside rising particle counts. Most fabs replace the ring on a fixed PM interval tied to RF hours or wafer count, then qualify with a monitor wafer.
Rings of this class use high-purity plasma-grade materials such as silicon, quartz or silicon carbide, chosen for erosion resistance and low particle generation. The specific grade is matched to the chamber and etch chemistry so the ring erodes predictably.
Yes. A worn or wrong-profile ring bends the sheath at the wafer edge, tilting ions and degrading edge uniformity, and can shed particles. The effect concentrates in the high-density edge dice, so yield can fall well before any tool alarm.
Typical lead time is 4–5 weeks. Quote ESCT P/N ES7099-070 (or OEM P/N 3D10-250576-21) when ordering so the correct ring is matched to your TEL chamber, and plan safety stock around your PM cadence.
The TEL Focus Ring (OEM P/N 3D10-250576-21, ESCT P/N ES7099-070) is a high-purity plasma-facing consumable that defines the sheath boundary at the wafer edge in Tokyo Electron 300 mm etch chambers. By extending the plasma past the wafer perimeter, it governs edge uniformity, profile control and particle performance, the factors that determine edge-die yield. As a sacrificial part it erodes predictably and is replaced on a planned PM interval. Supplied as a 2nd Source NEW, OEM-compatible ring with a typical 4–5 week lead time, it offers a cost-effective, schedule-friendly route to keeping TEL etch chambers within edge specification.
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 3D10-250576-21. 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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