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The focus ring is the annular consumable that surrounds the wafer at the outer edge of a Tokyo Electron (TEL) Lab 360-5T plasma etch chamber. Seated concentrically around the wafer on the lower electrode (cathode) assembly, it forms the boundary between the active process area and the chamber periphery. Although it is a passive component with no moving parts, its position directly in the plasma sheath makes it one of the most influential parts in determining whether the outermost few millimetres of every wafer etch to specification.
In a 300 mm process, the silicon wafer ends abruptly at its 150 mm radius, and without an electrically and geometrically matched ring around it the plasma sheath would bend sharply at that edge. That bending tilts ion trajectories, distorts the local etch rate and produces non-vertical feature profiles in the edge exclusion zone. The focus ring extends the effective electrical and physical surface of the wafer outward, so the plasma sheath stays flat and parallel across the wafer edge and ion bombardment remains vertical right out to the last die.
Because it sits squarely in the path of energetic ions and reactive radicals, the focus ring erodes throughout its service life. Its dimensions, material composition and electrical characteristics are therefore specified tightly, and it is replaced on a defined preventive-maintenance cadence. The ESCT Fab Support part ES7099-104 is a second-source equivalent to TEL OEM P/N 2L10-251717-11, manufactured to match the form, fit and function of the original ring used on the Lab 360-5T SA configuration.
The focus ring performs several closely related jobs at the wafer edge, all of which contribute to edge-to-edge process uniformity and to the stability of the plasma over the full wafer area:
Focus rings for 300 mm etch chambers are produced from high-purity materials chosen to match the chemistry of the process and to minimise particle and metallic contamination. Silicon and silicon carbide are common where the ring must behave electrically much like the wafer itself and contribute no foreign species to the etch; quartz and high-purity ceramics are used where a dielectric edge is required. The material is selected so that as the ring erodes it releases only species already present in the process, rather than introducing contaminants that would damage device yield.
A focus ring only does its job if its geometry is held to the original specification. Inner and outer diameter, height, step profile and flatness all influence how the sheath bends at the wafer edge, so each of these is controlled during manufacture. Surface finish matters too: a consistent finish keeps erosion even and reduces the rate at which redeposited material flakes away as particles.
Because the focus ring governs conditions in the edge exclusion zone, its condition is felt directly in the metrics fabs watch most closely. A worn, mis-seated or out-of-spec ring shows up as edge yield loss long before the centre of the wafer is affected:
The dominant wear mode is steady erosion from continuous ion bombardment and chemical attack. As the ring’s upper surface recedes and its height falls, the position of the plasma sheath at the wafer edge changes, gradually shifting edge etch rate and profile out of specification. This is the wear that defines the ring’s RF-hour service interval and the reason it is treated as a scheduled consumable rather than a fix-on-failure item.
Repeated thermal cycling, mechanical handling and any seating that leaves the ring unsupported can initiate cracks. A cracked focus ring is a serious risk because it can shed large particles onto the wafer, disturb the local plasma, and in the worst case fragment inside the chamber, forcing an unscheduled wet clean and parts replacement.
Process by-products build up on and around the ring over time. When that film flakes it becomes a particle source on the wafer edge. A ring that is not seated flat, because of debris under it or an erosion-induced change in fit, tilts the sheath asymmetrically and produces an azimuthal, non-uniform signature in edge results that can be hard to diagnose unless the ring is inspected.
Focus ring replacement is a routine preventive-maintenance task, but it must be carried out cleanly and precisely to preserve chamber matching. The following sequence reflects good practice; always follow your site’s TEL maintenance procedure and safety controls.
Focus rings are consumed continuously, so steady availability matters as much as the part itself. ESCT Fab Support supplies ES7099-104 as a second-source equivalent to TEL OEM P/N 2L10-251717-11, helping fabs hold their edge-uniformity performance while managing cost and supply risk:
It surrounds the wafer at the cathode edge and extends the plasma sheath beyond the physical wafer boundary, keeping ion trajectories vertical and the etch uniform out to the wafer edge. It also shields the electrode hardware beneath it from plasma attack.
No. ES7099-104 is a second-source, new part supplied as an OEM-compatible equivalent to TEL OEM P/N 2L10-251717-11. It is verified to match the form, fit and function of the original ring, but it is not an original TEL OEM component and is not sold as one.
Focus rings are scheduled consumables, typically replaced on an RF-hour or wafer-count basis defined by your process and PM plan. The right interval is the point at which erosion and height loss begin to push edge etch results toward the limits of your specification.
Edge etch rate and profile drift out of specification, critical-dimension uniformity degrades and particle counts can rise. In extreme cases the ring erodes enough to expose the electrode hardware underneath, turning a routine consumable swap into a far more costly repair.
It can if not managed. Because sheath geometry depends on ring height, fabs track ring age per chamber and run qualification wafers after replacement so that chambers in a matched group continue to behave consistently.
The indicative lead time is 4–5 weeks. Because focus rings are consumed continuously, we recommend planning buffer stock against your PM cadence so replacements are always on hand when a ring reaches end of life.
The focus ring (TEL OEM P/N 2L10-251717-11, ESCT P/N ES7099-104) is the edge-confinement consumable that keeps a TEL Lab 360-5T SA plasma etch chamber uniform out to the wafer edge. By extending the plasma sheath beyond the wafer and shielding the electrode hardware below, it protects edge yield, particle performance and chamber matching. As a continuously eroding scheduled consumable, it rewards a disciplined replacement strategy and reliable supply, which is exactly what ESCT Fab Support provides with a verified, cost-effective second-source equivalent.
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 2L10-251717-11. 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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