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The TEL focus ring identified by the variant code T4G50L-G2TMF and OEM part number 3D10-250807-21 is a chamber consumable that sits in the immediate annular zone surrounding a 300 mm wafer inside a Tokyo Electron plasma etch process chamber. It is one of the most influential single components governing how a process behaves at the extreme edge of the wafer, the very region where uniformity, yield and device-to-device repeatability are hardest to control. As a focus ring, its job is to extend and shape the plasma sheath beyond the wafer perimeter so that ions arrive at the outermost dies with the same trajectory, flux and angular distribution they experience across the wafer centre.
Physically, the part is a precision-machined ring that rests on or around the electrostatic chuck (ESC) assembly, concentric with the wafer and flush with or slightly proud of the wafer surface. Because it occupies the boundary between the energised cathode region and the grounded chamber surroundings, it is continuously exposed to ion bombardment, reactive radicals and thermal cycling. It is, by design, a sacrificial item, it is intended to erode in a controlled manner so that the silicon wafer and the more expensive chuck hardware beneath it do not.
Understanding this component matters because focus ring condition drives edge etch performance directly. As the ring wears, the sheath geometry at the wafer edge changes, edge tilt and critical-dimension uniformity drift, and ultimately edge dies are lost. Maintaining a focus ring within its serviceable envelope is therefore central to keeping a TEL etch chamber producing within specification.
In a Tokyo Electron 300 mm capacitively coupled etch chamber, the focus ring performs several interlinked electrical, plasma and thermal functions simultaneously. It is not merely a mechanical spacer; it is an active participant in shaping the discharge at the wafer edge.
Focus rings for TEL etch chambers are produced from plasma-grade materials chosen for their erosion behaviour, electrical character and particle performance under sustained ion bombardment. The exact material selected for a given recipe, typically high-purity silicon, silicon carbide, or quartz depending on chemistry and process window, determines how the ring ages and how it interacts with the discharge.
The ring is engineered to erode predictably and uniformly so that sheath geometry change is gradual and can be compensated. Material purity, grain structure and surface finish govern the erosion rate, the rate at which the ring’s exposed height recedes, and the tendency to form micro-roughness that sheds particles.
The ring’s resistivity and dielectric behaviour set how RF energy couples through it to the edge plasma, while its thermal conductivity and contact area influence the wafer-edge temperature profile. A correctly specified ring keeps the edge electrical and thermal environment matched to the chamber’s qualified recipe.
Because the focus ring sets the boundary condition for the entire wafer-edge process, its state propagates directly into measurable device and tool metrics. A worn, cracked or out-of-tolerance ring is a common root cause behind edge-zone excursions that are otherwise difficult to diagnose.
The dominant and expected failure mode is gradual sputter erosion. As accumulated RF hours mount, the exposed ring surface recedes, the sheath above the wafer edge drops and edge etch performance drifts out of specification. Once the ring falls below its serviceable height it must be replaced regardless of visual appearance.
Repeated thermal cycling, mishandling during preventive maintenance, or local hot spots can initiate cracks in brittle ceramic or silicon material. A cracked ring is a catastrophic failure, it sheds particles immediately, disturbs the local sheath and can liberate fragments onto the chuck or wafer.
Non-uniform etching, polymer deposition and redeposition can roughen the ring surface or build flaking films. These surfaces shed particulate that lands on the wafer as defects, so a ring that still meets height limits may still need replacement on particle grounds.
Focus ring replacement is a routine but precision-sensitive preventive maintenance task. Because the ring defines the edge process baseline, cleanliness, correct seating and post-installation qualification all matter. The sequence below outlines good practice; always follow the equipment owner’s approved PM procedure and safety controls.
Focus rings are high-turnover consumables, so holding qualified, ready-to-fit stock is fundamental to keeping etch chambers available. ESCT Fab Support supplies this ring, ES7099-058, as a second-source new part verified to the form, fit and function of TEL OEM P/N 3D10-250807-21, giving engineering teams a dependable alternative to single-source OEM supply.
It shapes and extends the plasma sheath beyond the 300 mm wafer edge so that ions strike the outermost dies at the correct angle and flux. This keeps edge etch profiles vertical and edge critical dimensions uniform, while also shielding the electrostatic chuck from ion bombardment.
No. This is a second-source new part, not an original OEM component. It is manufactured and supplied as a new item verified to match the form, fit and function of TEL OEM P/N 3D10-250807-21, offering an alternative to the original supply channel for the same chamber application.
Replacement is typically driven by accumulated RF hours, by the ring’s exposed height falling below the serviceable limit, by drift in edge uniformity and critical-dimension data, or by rising particle counts. Any visible crack means immediate replacement.
As the ring erodes, the sheath above the wafer edge drops and ion trajectories at the perimeter tilt. The outermost dies are the first to fall out of specification, so edge yield loss is usually the earliest and clearest symptom of a ring nearing end of life.
The current lead time is approximately 4-5 weeks. Because focus rings are consumed continuously, we recommend forecasting usage and holding buffer stock so PM events are never delayed waiting on supply.
As with any focus ring change, the chamber should be seasoned and requalified after installation using your standard edge uniformity, profile and particle checks. This confirms the new ring reproduces the qualified edge process before the tool returns to production.
The TEL focus ring T4G50L-G2TMF (OEM P/N 3D10-250807-21), supplied by ESCT as ES7099-058, is a critical edge-confinement consumable for Tokyo Electron 300 mm plasma etch chambers. Seated concentric with the wafer on the electrostatic chuck, it shapes the plasma sheath at the wafer edge, controls ion incidence angle, manages RF coupling and edge temperature, and protects the chuck from erosion. Because its condition translates directly into edge uniformity, critical-dimension control, particle performance and edge die yield, disciplined monitoring and timely replacement deliver it. Sourcing it as a verified second-source new part with a predictable 4-5 week lead time helps fabs keep etch chambers qualified and available while managing the cost of a high-consumption consumable.
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 3D10-250807-21. 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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