3D10-250317-21
CEL, OUTER, SH-OX,RP470-0.2

Outer silicon cathode electrode ring (OEM P/N 3D10-250317-21), outer CEL edge electrode for TEL 300 mm plasma etch systems

ESCT P/N ES7099-020, outer cathode (CEL) ring for TEL plasma etch process chambers

The Outer Silicon Cathode Electrode Ring identified by Tokyo Electron part number 3D10-250317-21, and stocked by ESCT Fab Support as ES7099-020, is an outer-position cathode electrode (CEL) consumable used in TEL 300 mm plasma etch process chambers. The naming descriptor “CEL, OUTER, SH-OX” reflects its role as the outer cathode element that surrounds the inner electrode assembly directly beneath the wafer edge, with a surface-conditioned (oxide-treated) silicon working face. In the broader family of TEL cathode and electrode hardware, this component is the annular member that completes the powered electrode area at the periphery of the chuck, where the radial electric field transitions from the wafer zone out toward the grounded chamber wall.

Positioned concentrically around the wafer-bearing electrostatic chuck, the outer CEL ring sits in the same plasma-exposed plane as the focus and edge rings and is continuously bombarded by reactive ions during etch. Because it is part of the cathode (the RF-driven electrode), it does far more than simply shield the chuck periphery: it carries RF current, helps define the sheath geometry at the wafer edge, and presents a consumable silicon surface that participates in the etch chemistry rather than merely tolerating it. Its condition therefore has a direct and measurable effect on edge etch behaviour.

As a silicon consumable in an aggressive fluorine- and oxygen-bearing plasma environment, this ring is a scheduled-replacement item. Maintaining a supply of qualified outer cathode rings such as ES7099-020 allows fabs to preserve edge-to-edge process repeatability and to keep preventive maintenance windows short and predictable.

Functional role of the outer cathode ring in TEL plasma etch platforms

Within a TEL 300 mm etch chamber, the outer CEL ring works as the peripheral extension of the powered electrode, bridging the electrically active wafer region and the surrounding chamber furniture. Its key functions include the following.

• Extending the cathode electrode area radially outward so that the RF-driven surface continues smoothly beyond the wafer edge rather than terminating abruptly at the chuck.
• Shaping the plasma sheath at the wafer periphery so that ion trajectories remain near-vertical across the outermost dies, supporting uniform etch profiles to the wafer edge.
• Providing a defined RF return and current-distribution path around the chuck, helping to balance the radial impedance presented to the plasma.
• Offering a sacrificial, oxide-conditioned silicon surface that reacts predictably with the process chemistry, stabilising loading effects near the wafer edge.
• Protecting the underlying chuck periphery, clamp hardware and dielectric surfaces from direct ion bombardment and erosion.
• Maintaining the concentric mechanical reference that keeps adjacent focus and edge rings correctly seated relative to the wafer.

Material and process performance

Silicon purity and surface conditioning

As a cathode electrode element, the ring is manufactured from high-purity silicon with tightly controlled resistivity, because both its etch behaviour and its electrical contribution depend on consistent bulk material properties. The “SH-OX” surface designation points to a conditioned or oxide-bearing working face that influences initial seasoning behaviour and particle performance.

• High-purity silicon construction with controlled resistivity to keep RF coupling repeatable across the part’s service life.
• Surface-conditioned working face that minimises first-wafer effects after a fresh ring is installed and seasoned.
• Low residual metallic contamination, protecting sensitive device layers from cross-contamination at the wafer edge.
• Controlled flatness and dimensional tolerance so the silicon face sits in the intended plane relative to the wafer surface.

Plasma and chemical resistance

In service the ring faces continuous exposure to fluorine-, oxygen- and other halogen-bearing plasmas at elevated power densities. Its silicon body erodes in a predictable, controlled fashion, which is precisely why it is treated as a consumable and replaced on a defined schedule.

• Predictable, near-uniform erosion rate that supports a quantifiable replacement interval based on RF hours or wafer count.
• Resistance to thermal cycling between idle and high-power process states without micro-cracking at the working surface.
• Stable etch-by-product chemistry, helping to keep the chamber’s radical and ion balance consistent over time.
• Low particle generation when surfaces remain within their dimensional and roughness limits.

Impact on tool performance and yield

Because the outer cathode ring lies in the electrically and chemically active edge zone, its condition propagates directly into device results. A worn, eroded or out-of-tolerance ring shifts the edge sheath and chemistry, with consequences that show up first at the outermost dies.

• Edge etch rate drift and tilted or bowed profiles on the outer wafer ring, reducing usable die count.
• Degraded within-wafer uniformity as the radial sheath and impedance balance shift with erosion.
• Rising particle and defect counts from a roughened or pitted silicon surface, driving yield loss.
• RF instability or reflected-power excursions if the cathode area changes faster than the matching network can compensate.
• Increased chamber matching, requalification and unplanned downtime if replacement is deferred too long.

Common wear and failure modes

Erosion and thinning

The dominant wear mode is gradual erosion of the silicon working surface under ion bombardment. As the ring thins, the local sheath height and field geometry change, and the etch behaviour at the wafer edge drifts away from the qualified recipe window until the part reaches its replacement limit.

Surface pitting and particle shedding

Localised pitting, micro-roughening and flaking of redeposited material can develop on the silicon face over many cycles. These defects shed particles onto the wafer and into the chamber, raising defect density and forcing more frequent wet cleans or early ring replacement.

Cracking and seating faults

Thermal stress, mishandling during PM, or debris under the ring can lead to chips, cracks or an uneven seat. A ring that is cracked or not fully seated disturbs RF return paths and concentricity, producing asymmetric edge results and, in severe cases, arcing.

Installation and replacement guidance

Replacement should follow the TEL chamber’s documented preventive-maintenance procedure and cleanroom contamination controls. The outline below summarises good practice; always defer to the tool’s official PM documentation and safety interlocks.

• Vent the chamber per procedure, confirm RF and gas isolation, and allow surfaces to reach a safe handling temperature.
• Remove adjacent edge and focus rings as required to access the outer cathode ring, recording their order and orientation.
• Lift out the worn outer CEL ring and inspect the seating surface, cathode periphery and contact areas for residue, debris or damage.
• Clean the seat and mating surfaces with approved methods so the new ring beds flat with good electrical contact.
• Handle the new ES7099-020 ring with clean gloves or appropriate tooling, verify orientation, and seat it concentrically without forcing.
• Reinstall the surrounding rings, close the chamber, pump down and leak-check, then run the required seasoning and qualification recipes before production.
• Log the installation date, RF hours and any matching adjustments to anchor the next preventive-maintenance interval.

Spare parts strategy for TEL plasma etch cathode consumables

Outer cathode rings are recurring consumables, so a disciplined sourcing strategy protects both yield and uptime. ESCT Fab Support helps fabs keep these critical edge components on the shelf and qualified.

• New, second-source parts verified to the form, fit and function of TEL OEM P/N 3D10-250317-21.
• Single ESCT reference (ES7099-020) to simplify reordering and stores management.
• A typical lead time of 4-5 weeks, supporting planned replenishment ahead of scheduled PM windows.
• A cost-effective alternative to single-vendor supply, reducing exposure to OEM allocation and price volatility.
• Consistent material specification to help preserve repeatable edge etch performance across replacements.

Frequently asked questions

What does the outer cathode (CEL) ring actually do in the chamber?

It extends the powered electrode area around the wafer edge, shapes the plasma sheath at the periphery, carries part of the RF return current and presents a consumable silicon surface that participates in the etch chemistry. Together these roles keep edge etch profiles and uniformity within their qualified window.

Is this an original TEL OEM part?

No. ES7099-020 is supplied as a new, second-source part that is OEM-compatible with TEL part number 3D10-250317-21. It is verified to the form, fit and function of the original component but is not an original OEM part, and TEL trademarks and part numbers are quoted solely for cross-reference.

How often does the ring need replacing?

Replacement intervals depend on process chemistry, RF power and wafer throughput, so they are best set from each fab’s own RF-hour or wafer-count data. The ring is a scheduled consumable and is replaced once erosion or surface condition begins to push edge results toward the recipe limits.

What are the first signs that the ring is worn?

Typical early indicators include edge etch-rate drift, tilted profiles on the outer dies, rising particle or defect counts, and small increases in reflected RF power or matching position. Visual inspection during PM may reveal thinning, pitting or surface roughening of the silicon face.

Does a fresh ring require seasoning before production?

Yes. After installation the chamber should be pumped down, leak-checked and run through the recommended seasoning and qualification recipes so the new silicon surface stabilises and the matching network settles before product wafers are processed.

What is the lead time and how should I order?

The typical lead time is 4-5 weeks, so it is best ordered ahead of planned maintenance. Quote ESCT P/N ES7099-020, or the OEM reference 3D10-250317-21, and confirm your chamber configuration with the ESCT team to confirm the correct fit.

Summary

The Outer Silicon Cathode Electrode Ring (ESCT P/N ES7099-020, OEM P/N 3D10-250317-21) is a high-purity silicon consumable that completes the powered electrode at the wafer edge in TEL 300 mm plasma etch chambers. By extending the cathode area, shaping the edge sheath, carrying RF return current and providing a conditioned sacrificial surface, it directly governs edge etch uniformity, particle performance and yield. Treating it as a scheduled-replacement item, and keeping qualified stock on hand through ESCT Fab Support, helps fabs hold tight edge process control while keeping maintenance predictable and cost-effective.

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 3D10-250317-21. 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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