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The Inner Cover Ring 344.8 Si V2 is a silicon consumable that sits within the upper electrode and chamber-lid assembly of Tokyo Electron 300 mm plasma etch chambers, where it shields the structural and metallic surfaces immediately inboard of the gas-distribution and electrode hardware from direct plasma exposure. The “344.8” designation reflects the ring’s nominal diameter class in millimetres, dimensioning it to ring the active process zone above a 300 mm wafer, while the “V2” revision marks a refined geometry or material specification released by the OEM to improve confinement behaviour, particle performance or service life over the original part.
As an inner cover ring fabricated from process-grade silicon, this component performs two intertwined duties at once. It is a sacrificial barrier that takes the brunt of ion bombardment and radical attack so that anodised aluminium, quartz and other lid-side surfaces behind it remain protected; and it is an electrically and chemically matched extension of the silicon surfaces around the discharge, so that the plasma “sees” a consistent material at the chamber boundary. Because it is silicon rather than a dielectric insulator, it participates in the chamber’s chemistry and electrical environment rather than merely masking hardware.
In a process where edge uniformity, defect density and chamber-to-chamber matching directly determine die yield, a cover ring of the correct material grade and dimensional revision is not a cosmetic shield. It is part of the tuned hardware set that defines how the plasma terminates at the chamber wall, and replacing it with a verified equivalent keeps a fleet of TEL etch chambers behaving identically.
Within a TEL 300 mm plasma etch chamber the inner cover ring occupies the annular region around the active discharge, typically associated with the upper electrode, gas-distribution or lid assembly. From that position it shapes the plasma boundary and protects the hardware it surrounds. Its principal functions include the following.
Process-grade silicon is chosen for cover rings because it is chemically compatible with fluorine- and bromine-based etch chemistries and because its erosion produces volatile species rather than non-volatile metallic contaminants. A correctly specified silicon ring erodes slowly and cleanly, contributing little to the particle and metals budget of the chamber. Purity, resistivity and crystalline or polycrystalline form all influence how the surface interacts with the discharge and how it ages, which is why the V2 material and dimensional revision must be matched exactly.
Beyond bulk material, the ring’s diameter, thickness, flatness and surface finish govern how well it seats against its mounting surface and how cleanly the plasma terminates at its edge. Tight tolerances on the 344.8 mm form let the ring concentrically frame the process zone, while a controlled surface finish limits localised field enhancement and particle shedding. Deviation from the V2 specification can shift the plasma boundary and degrade uniformity.
Although it is a passive consumable, the inner cover ring sits directly at the plasma boundary and therefore influences several outcomes that matter to the fab. A worn, mis-specified or contaminated ring can quietly erode yield long before it triggers an obvious fault.
The dominant ageing mechanism is steady erosion of the silicon surface by ion bombardment and chemical attack. Over thousands of RF hours the ring thins, edges round over and the exposed profile changes, gradually shifting the plasma boundary and the edge process response. Once erosion reaches the service limit the ring must be replaced to restore the intended geometry.
As the surface roughens and polymer or by-product films build up, the ring can begin to shed particles or flake redeposited material onto the wafer. Rising on-wafer defect counts or sudden particle excursions are common indicators that the cover ring has aged beyond its useful window and is contributing to yield loss.
Silicon is brittle, so thermal cycling, mishandling during service, or improper seating can produce micro-cracks, chips or fracture. A poorly seated or damaged ring can also create gaps that promote localised arcing, which accelerates erosion at that point and risks damaging adjacent hardware. Any visible crack or chip warrants immediate replacement.
Replacement should follow the TEL maintenance procedure for the specific chamber and always be performed by trained personnel under appropriate cleanroom and safety controls. The following sequence summarises good practice.
Silicon cover rings are recurring consumables, so a dependable supply that matches OEM form, fit and function is central to keeping etch chambers productive and well matched. ESCT Fab Support supplies the ES7099-120 inner cover ring as a verified alternative to the TEL part, with the advantages below.
It is a silicon barrier that surrounds the active plasma zone near the upper electrode and lid. It protects the hardware behind it from ion and radical attack while presenting a process-matched silicon surface that helps keep the plasma boundary stable and the edge etch uniform.
No. ES7099-120 is supplied as a new, 2nd-source, OEM-compatible part verified to the form, fit and function of TEL OEM P/N 2L10-355558-11. It is not an original OEM part and is not sold as one.
The number reflects the ring’s nominal diameter class in millimetres, “Si” confirms it is silicon, and “V2” denotes the OEM revision level. Matching the revision matters because geometry and material refinements affect plasma confinement, particle performance and service life.
Replace it when accumulated RF hours reach the chamber’s service limit, when erosion visibly thins or rounds the profile, or when particle counts and edge uniformity drift outside specification. Any crack, chip or arcing damage calls for immediate replacement.
Used as intended, a correctly specified ES7099-120 supports matching because it reproduces the OEM dimensions and silicon material. As with any consumable change, verify edge uniformity and particle baselines after installation before returning the chamber to full production.
The typical lead time is 4-5 weeks. Because cover rings are recurring consumables, we recommend aligning orders with planned preventive-maintenance cycles and holding suitable safety stock to avoid unplanned chamber downtime.
The Inner Cover Ring 344.8 Si V2 (ESCT P/N ES7099-120, OEM P/N 2L10-355558-11) is a process-grade silicon consumable that frames the plasma zone in TEL 300 mm etch chambers, shielding inboard hardware, presenting a stable silicon boundary and supporting edge uniformity, particle performance and chamber-to-chamber matching. Supplied as a new 2nd-source part verified to OEM form, fit and function with a 4-5 week lead time, it offers fabs a cost-effective, dependable way to keep etch chambers productive and matched between preventive-maintenance cycles.
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 2L10-355558-11. 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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