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The Silicon Cathode Outer Electrode Ring (CEL, OUTER, GAP30) is a circular consumable component that sits at the periphery of the powered electrode assembly in Tokyo Electron (TEL) 300 mm plasma etch process chambers. Designated by TEL part number 3D10-251042-11 and supplied by ESCT Fab Support under part number ES7099-096, it forms the outer annulus of the cathode (CEL) stack that surrounds the wafer-bearing region of the lower electrode. As an exposed electrode part, it is fully immersed in the plasma during processing and plays an active role in defining how RF power, ion flux and reactive species are distributed across the wafer edge.
In a 300 mm etch chamber, the lower electrode is a layered assembly. A focus ring or edge ring rests at the immediate wafer perimeter, and beneath and outboard of it sit further silicon and ceramic components that complete the electrical and geometric boundary of the plasma. The cathode outer ring occupies this outboard position, bridging the active electrode area to the grounded chamber liner. The “GAP30” designation refers to the engineered gap geometry of this specific build variant, which sets the spacing between the outer electrode and adjacent surfaces and therefore the local electric field at the chamber edge.
Because it lies directly in the plasma and at the transition between powered and grounded surfaces, the part is both an electrical element and a sacrificial consumable. It is consumed gradually by ion bombardment and chemical attack, and its condition has a measurable effect on edge etch uniformity, plasma confinement and particle performance. Maintaining it as a tracked spare therefore keeps a fleet of TEL etch chambers matched and productive.
The cathode outer electrode ring performs several overlapping electrical, plasma and mechanical functions at the chamber edge. It is not a passive spacer; its silicon construction and precise geometry make it part of the active electrode system.
Cathode electrode rings of this type are manufactured from high-purity silicon selected to match the chemical behaviour of the wafer surface and to minimise metallic contamination. The grade, resistivity and surface finish are specified so the ring etches predictably and contributes the intended amount of silicon to the gas-phase chemistry. Trace-metal cleanliness is critical, because any contamination liberated at the chamber edge can migrate to the wafer and degrade device yield.
The GAP30 build variant carries specific edge-gap and flatness tolerances that determine how the plasma behaves at the chamber periphery. Concentricity, parallelism and the controlling gap dimension must be held tightly so the electric field at the wafer edge is reproducible from chamber to chamber. Even small deviations alter the sheath profile and shift edge etch rate, which is why this part is manufactured to verified OEM form, fit and function rather than as an approximate substitute.
Because the cathode outer ring governs field and chemistry at the wafer edge, its condition propagates directly into process results. A worn, eroded or incorrectly specified ring shows up first as edge-region drift and rising particle counts long before the chamber faults outright.
The dominant wear mechanism is gradual erosion of the silicon surface by ion bombardment and chemical etching. Over many RF hours the ring thins and the GAP30 dimension opens up, shifting the edge field and degrading uniformity. Erosion is expected and is the basis for treating the ring as a scheduled consumable with a defined replacement interval.
Silicon is brittle, so thermal cycling, mechanical stress during handling and localised hot spots can produce cracks or chips. Fractured edges create particle sources and disrupt the electrical continuity of the electrode boundary. Handle it carefully and seat it correctly to avoid introducing damage during installation.
In polymerising chemistries, deposits accumulate on the ring surface and in the edge gap. Build-up changes local impedance and surface chemistry, and flaking deposits become particle defects. When erosion and contamination combine, the ring can no longer hold its qualified process window and must be replaced.
Replacement should follow TEL maintenance procedures for the specific chamber and be carried out by trained personnel under appropriate cleanroom and ESD controls. The following sequence summarises good practice.
Cathode outer rings are recurring consumables, so holding qualified spares on the shelf is central to maximising chamber availability. ESCT Fab Support supplies ES7099-096 as a cost-effective second-source alternative to the OEM part, helping fabs control spend and avoid unplanned downtime.
It forms the outer annulus of the powered electrode (CEL) assembly, extending the electrode area beyond the wafer and setting the engineered edge gap. In doing so it shapes the electric field, confines the plasma and contributes silicon to the etch chemistry at the wafer edge, all of which affect edge uniformity and particle performance.
No. ES7099-096 is supplied as a new, second-source part that is OEM-compatible and verified to the form, fit and function of TEL 3D10-251042-11. It is not an original Tokyo Electron part and is not sold as one; it is an alternative that meets the same functional specification.
GAP30 identifies a specific build variant defined by its engineered edge-gap geometry. That gap dimension controls the spacing between the outer electrode and adjacent surfaces, which in turn sets the local impedance and field shaping at the chamber edge. Always match the variant to your chamber configuration.
It is manufactured from high-purity silicon with controlled resistivity and surface finish, selected for plasma compatibility, predictable erosion and low trace-metal contamination so that it protects wafer-edge yield throughout its service life.
Replacement is usually driven by RF hours or wafer count, supported by process monitoring. Rising edge-region drift, increasing particle counts, visible thinning or cracking, and difficulty holding the qualified process window all indicate the ring has reached the end of its useful life.
The indicative lead time is 4-5 weeks. Order from ESCT Fab Support by quoting ESCT P/N ES7099-096 or the TEL reference 3D10-251042-11, and our team can confirm suitability for your chamber before you commit.
The Silicon Cathode Outer Electrode Ring, GAP30 (TEL 3D10-251042-11, ESCT ES7099-096) is a high-purity silicon consumable that occupies the outboard position of the powered electrode in TEL 300 mm plasma etch chambers. It shapes the wafer-edge electric field, sets the engineered GAP30 spacing, confines the plasma and supports the RF return path, while acting as a sacrificial surface that protects costlier hardware. As a wear part, its condition directly affects edge uniformity, particle performance and chamber matching, making a reliable, well-specified spare an important part of any TEL etch maintenance strategy. ESCT supplies this ring as a new, OEM-compatible second source with a clear cross-reference and a 4-5 week lead time.
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 3D10-251042-11. 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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