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The cathode electrode, abbreviated CEL in Tokyo Electron (TEL) parts nomenclature, is one of the most consequential components in a 300 mm plasma etch process chamber. It is the lower, powered electrode that sits directly beneath the wafer-handling stack and forms the active half of the capacitively coupled RF circuit. Where the upper electrode and chamber walls define one boundary of the discharge, the cathode defines the other, and it is across this gap that the plasma sheath develops and ion energy is set. Identified here under TEL OEM part number 3D10-250871-11 and supplied by ESCT Fab Support as ES7099-159, this cathode is engineered to restore original RF coupling, thermal contact and mechanical registration in TEL 300 mm etch platforms.
In a TEL etcher, the cathode is not a passive plate. It carries RF power up into the process region, provides the conductive return path that completes the discharge circuit, and serves as the structural and thermal foundation on which the electrostatic chuck, focus ring and edge consumables are stacked. Because it is positioned at the very bottom of the plasma volume and is biased to draw ions toward the wafer, the cathode experiences sustained ion bombardment, thermal cycling and exposure to aggressive fluorocarbon and oxygen-based etch chemistries. Its condition therefore has a direct, measurable bearing on etch rate, sheath uniformity and the stability of the process from wafer to wafer.
When a cathode degrades, the symptoms rarely stay confined to a single parameter. Edge-to-centre etch non-uniformity, drifting bias voltage, intermittent RF arcing and rising particle counts can all trace back to a worn, eroded or poorly seated cathode. Replacing it on a planned schedule, rather than after a yield excursion, is one of the more cost-effective decisions a fab can make in protecting both throughput and device performance.
The CEL cathode performs several tightly coupled roles simultaneously, spanning electrical, thermal and mechanical domains. Each must be maintained within specification for the chamber to deliver repeatable results across a production campaign.
Because the cathode surface is continuously bombarded by energetic ions, its material composition and surface finish are critical. TEL cathode electrodes are built to withstand prolonged exposure to fluorocarbon, oxygen and inert-gas plasmas while keeping sputter erosion and surface roughening to a minimum. A stable, low-erosion surface preserves the intended RF coupling and keeps the cathode from becoming a source of metallic or particulate contamination as it ages.
The cathode must hold tight flatness and dimensional tolerances across repeated thermal cycles. Any warping, distortion or loss of flatness degrades the thermal contact between the cathode, chuck and wafer, which in turn shifts wafer temperature and etch rate. Stable material behaviour under thermal load is therefore as important as raw erosion resistance.
As the powered electrode and structural base of the wafer stack, the cathode sits at the intersection of nearly every etch performance metric. Its condition propagates directly into the results seen on production wafers, which is why fabs treat it as a controlled, scheduled-replacement item rather than a run-to-failure component.
The most common degradation mechanism is gradual erosion of the cathode surface under ion bombardment. As the surface roughens and recedes, RF coupling drifts, the sheath becomes less predictable and etch rate begins to wander. Eroded material can also redeposit elsewhere in the chamber or break loose as particles, raising defect counts before the cathode reaches the end of its mechanical life.
Over many cycles, the RF contact interfaces and grounding surfaces can oxidise, accumulate deposits or loosen. The resulting rise in contact impedance promotes localised arcing, which damages both the cathode and adjacent hardware, injects particles into the chamber and can trip the match network. Arc events are often the first clear warning that the cathode and its contact surfaces need attention.
Repeated thermal cycling can induce slow distortion or loss of flatness in the cathode. This degrades thermal contact with the chuck and wafer, creating temperature non-uniformity that shows up as edge-to-centre etch variation. Poor flatness also compromises the seating of the focus ring and edge consumables, compounding uniformity problems across the stack.
Cathode replacement is a precision task that should be carried out by trained personnel following the TEL maintenance procedure for the specific tool. The steps below outline the typical sequence; always defer to the official documentation and your fab’s qualification protocol.
Cathodes are scheduled-replacement items, so holding qualified spares is central to keeping a TEL etch fleet productive. ESCT Fab Support helps fabs manage cathode supply without over-committing to single-source OEM channels.
It is the lower, powered RF electrode beneath the wafer. It delivers RF power into the process region, sets the self-bias that controls ion energy, completes the discharge return path, and acts as the thermal and structural base for the chuck and edge consumables.
No. ES7099-159 is supplied as a second-source new, TEL-compatible cathode. It is a brand-new part manufactured to match the original specification and is verified to original form, fit and function, but it is not an original OEM-branded component.
Common indicators include drifting etch rate or self-bias, worsening edge-to-centre uniformity, rising particle or defect counts, and RF arcing events. Most fabs replace the cathode on a planned interval driven by RF hours or wafer count rather than waiting for these symptoms.
Because it is built to match the original cathode dimensions, materials and RF characteristics, it is intended to drop into the existing process window. As with any consumable replacement, you should run your standard RF, temperature and process-qualification checks before returning the tool to production.
Typical lead time is 4-5 weeks. We recommend aligning orders with your preventive-maintenance schedule and holding a qualified spare on the shelf to avoid downtime if a cathode fails earlier than expected.
Yes. Our technical team can confirm fit against TEL OEM P/N 3D10-250871-11 and your chamber configuration, and assist with broader spares planning across your TEL 300 mm etch fleet.
The CEL cathode electrode (TEL OEM P/N 3D10-250871-11, ESCT P/N ES7099-159) is the powered lower electrode at the heart of a Tokyo Electron 300 mm plasma etch chamber. It delivers RF power, sets ion energy through self-bias, completes the discharge return path and provides the thermal and structural foundation for the wafer stack. As an erosion-exposed consumable, its condition drives etch rate stability, critical-dimension control, edge uniformity and particle performance. Supplied as a second-source new, TEL-compatible part verified to form, fit and function, ES7099-159 gives fabs a reliable, well-supported alternative for keeping TEL etch tools qualified and productive.
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 3D10-250871-11. 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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