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The focus ring described by the OEM designation 2L10-251855-11 is a circumferential consumable that sits in the periphery of the lower electrode assembly inside a Tokyo Electron (TEL) 300 mm plasma etch chamber. The “344.5” in the part name refers to its nominal outer diameter in millimetres, a dimension chosen so that the ring frames a 300 mm wafer with a controlled annular gap, surrounding the wafer edge with a sacrificial surface that carries the plasma sheath outward beyond the silicon. In service it is one of the most influential pieces of hardware in the entire etch kit, because it dictates what the plasma “sees” at the wafer edge.
Because it is positioned directly in the path of energetic ions and reactive radicals, the focus ring is a wear part by design. The “REWORK” prefix in the raw part name reflects how these rings are managed in the field: they are precision-machined components whose critical surfaces erode over thousands of RF hours, and they are routinely replaced or reworked to restore the original profile. ESCT supplies ES7099-111 as a 2nd-source, newly manufactured ring built to match the form, fit and function of the TEL original, giving fabs a cost-controlled, lead-time-friendly alternative to single-sourcing this high-turnover consumable.
Understanding why a single ring matters so much starts with the physics of the wafer edge. Without a focus ring, the plasma sheath would bend sharply where the conductive silicon wafer ends, distorting ion trajectories and causing the outermost dies to etch at the wrong rate and the wrong angle. The 344.5 mm ring extends the effective electrical and topographical surface past the wafer, so that the sheath stays flat and the edge dies behave like the centre.
In a TEL 300 mm etch chamber the focus ring works alongside the electrostatic chuck, the cover/insulator rings and the upper electrode to shape the plasma at the wafer perimeter. Its responsibilities are both electrical and geometric:
Focus rings of this class are produced from process-matched materials, most commonly high-purity silicon, but also silicon carbide or quartz depending on the chemistry and the OEM recipe, chosen so that any sputtered material is compatible with the process and does not introduce metallic or particulate contamination. Material grade matters because it sets both the erosion rate and the contamination signature of the ring over its life.
The 344.5 mm outer diameter, the inner step that registers against the wafer edge, the seat flatness and the surface finish are all toleranced features. Small departures in any of them shift the sheath and degrade edge uniformity, which is why a reworked or replacement ring must reproduce the OEM geometry faithfully rather than approximately.
Because the focus ring controls the etch environment exactly where edge dies live, its condition maps almost directly onto edge yield. As the ring erodes, the sheath above the wafer edge drops and tilts, and the consequences appear in the data well before any visible damage:
The dominant failure mode is gradual erosion of the upper surface by ion bombardment. As the ring thins, the step height relative to the wafer changes, the sheath recedes and edge uniformity degrades. This is an expected end-of-life mechanism and is the primary reason the ring is treated as a scheduled-replacement consumable.
Brittle ring materials are vulnerable to thermal-shock cracking and to mechanical chipping during handling, transfer or seating. A cracked ring can shed large particles onto the wafer edge and may compromise the electrical and thermal contact with the chuck periphery, so any chip or crack found during inspection warrants immediate replacement.
Process by-products and polymer can accumulate on and around the ring, flaking off as defects or creating conditions for localised arcing. Arcing damage roughens the surface, accelerates erosion and can leave burn marks that disturb the local field, all of which feed back into edge non-uniformity.
Focus ring replacement is a routine preventive-maintenance task on TEL etch tools, but it must follow the OEM procedure for the specific chamber. The following sequence is a general outline and does not replace the documented work instruction for your platform:
Focus rings are high-frequency consumables, so the way a fab sources them has a direct effect on cost per wafer and chamber availability. ESCT supplies ES7099-111 as part of a broader TEL etch consumable programme designed around predictable supply and verified quality:
It is the nominal outer diameter of the ring in millimetres. At 344.5 mm the ring frames a 300 mm wafer with a controlled annular gap, positioning its sacrificial surface just beyond the wafer edge so the plasma sheath stays flat across the outermost dies.
No. ES7099-111 is a 2nd-source, newly manufactured, OEM-compatible focus ring. It is built and verified to match the form, fit and function of the TEL original 2L10-251855-11, but it is not an original OEM part and is not supplied as one.
The term reflects how these precision rings are managed as wear parts, their critical surfaces are restored or replaced on a maintenance cycle. ESCT supplies this item as a new, ready-to-install ring that fulfils that replacement role.
The usual indicators are drifting edge etch rate and CD uniformity, tilted edge profiles, rising edge particle or defect counts, and an accumulated RF-hour count approaching the limit your process of record defines. Visible erosion, cracking or arcing damage at inspection are immediate replacement triggers.
The typical lead time is 4-5 weeks. Because focus rings are consumed regularly, we recommend aligning orders with your preventive-maintenance plan and holding appropriate buffer stock to protect chamber uptime.
Because it is manufactured to the OEM geometry and a process-matched material grade, it is intended to drop into the existing recipe and chamber-matching framework. As with any consumable change, install a fresh ring during scheduled maintenance and confirm edge performance with a monitor wafer before returning the chamber to production.
The 344.5 mm focus ring (OEM P/N 2L10-251855-11, ESCT P/N ES7099-111) is a critical edge-confinement consumable for TEL 300 mm plasma etch chambers. By extending the plasma sheath beyond the wafer and defining the annular gap at the wafer edge, it governs edge etch uniformity, profile control and particle performance on the outermost dies, the region where yield is most easily lost. As a sacrificial part it erodes, cracks or accumulates deposition over its RF life and must be replaced on a maintenance schedule. ESCT supplies it as a 2nd-source, newly manufactured, OEM-compatible ring with a 4-5 week lead time, giving fabs a cost-effective and dependable way to keep their TEL etch chambers on 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 2L10-251855-11. 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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