3D10-202364-12
CLE INNER

Inner cathode electrode (OEM P/N 3D10-202364-12), silicon lower-electrode cathode for TEL 300 mm plasma etch systems

ESCT P/N ES7099-168, inner CEL silicon cathode component for Tokyo Electron (TEL) etch process chambers

The Inner Cathode (TEL designation “CLE INNER”, part of the lower cathode electrode assembly, or CEL) is a high-purity silicon consumable that forms the inner region of the powered lower electrode in a Tokyo Electron 300 mm plasma etch chamber. It sits directly beneath and concentric with the electrostatic chuck and wafer, occupying the central footprint of the RF-driven cathode stack. In capacitively coupled etch reactors, the cathode is the surface through which RF power is delivered into the plasma, and the inner cathode section is the part that lies most directly under the bulk of the 300 mm wafer.

Because it is fabricated from process-grade silicon rather than a metal, the inner cathode does double duty: it conducts and couples RF energy upward into the discharge while also presenting a silicon surface that participates chemically and electrically in the etch. As a sacrificial silicon member exposed to fluorine and bromine chemistries, energetic ion bombardment and high heat flux, it is a defined consumable that is monitored, qualified and replaced on a wear schedule rather than treated as a permanent structural element.

Its condition has a direct, measurable effect on centre-of-wafer etch rate, plasma symmetry and particle performance. A worn, cracked or contaminated inner cathode is one of the more common root causes of slow drift in process results across a chamber’s service life, which is why fabs hold qualified replacements on the shelf and refresh the part during scheduled preventive maintenance.

Functional role of the inner cathode in TEL etch platforms

Within the lower-electrode (CEL) assembly, the inner cathode performs several overlapping electrical, thermal and process functions that together define how the centre of the wafer is etched:

• Couples RF power from the powered electrode stack into the plasma across the central region of the 300 mm wafer, helping to set the sheath voltage and ion energy at the wafer surface.
• Establishes the inner boundary of the electrode area, working with the outer cathode and surrounding ring set to shape the radial distribution of plasma density and DC bias.
• Provides a silicon surface that is consumed in preference to other chamber parts, acting as a sacrificial member and helping to scavenge reactive fluorine species from the discharge.
• Conducts heat away from the central electrode region into the cooled cathode base, supporting a stable thermal profile under the wafer.
• Maintains a defined, repeatable gap and surface geometry directly below the chuck so that the electric field and gas conductance in the centre stay consistent run-to-run.
• Contributes to the RF return path geometry, influencing how current flows symmetrically back from the plasma through the cathode structure.

Material and process performance

The performance of an inner cathode is governed almost entirely by the quality of the silicon and the precision of its machined and finished surfaces. Both factors must match the OEM specification closely for the part to behave identically in the chamber.

Silicon purity and resistivity

Inner cathodes are made from high-purity silicon with controlled bulk resistivity so that RF coupling and the rate of silicon consumption stay within the window the process was developed around. Trace metallic impurities or out-of-band resistivity can shift centre etch rate, alter selectivity and introduce a metals contamination risk on the wafer.

• High-purity silicon stock to minimise metallic and mobile-ion contamination of the wafer.
• Resistivity held to specification to keep RF coupling and bias behaviour consistent with the qualified process.
• Uniform bulk quality so etch-by-plasma erosion proceeds evenly rather than preferentially at defects.

Surface finish and dimensional accuracy

Flatness, thickness, hole and slot positions, and the surface finish of the inner cathode all feed directly into field uniformity and gas flow in the centre of the chamber. Out-of-tolerance geometry changes the local gap, distorts the field and can seed particles or hot spots.

• Precision-machined flatness and thickness to preserve the cathode-to-wafer gap and field uniformity.
• Controlled surface finish to manage erosion rate and limit particle generation as the silicon is consumed.
• Accurate gas-feed and mounting features so conductance and clamping load match the original part.
• Clean, residue-free finish supplied ready for low-particle installation.

Impact on tool performance and yield

Because the inner cathode sits under the centre of the wafer and carries RF into the plasma there, its condition propagates straight into the parameters fabs watch most closely:

• Centre-to-edge etch rate uniformity, since erosion or warping of the inner cathode skews the radial profile.
• Critical dimension and profile control across the central die, which depend on stable ion energy and bias.
• Particle counts and on-wafer defectivity, which rise sharply once the silicon surface degrades or cracks.
• Chamber-matching, because a worn or mismatched inner cathode pushes one tool away from its peers.
• Mean time between cleans and overall tool availability, as drift forces more frequent re-qualification.
• Scrap and rework cost, where an out-of-spec centre profile can compromise an entire wafer lot.

Common wear and failure modes

As a sacrificial silicon consumable, the inner cathode is expected to wear; the goal of a sound spares strategy is to replace it before that wear degrades results. The dominant degradation mechanisms are:

Plasma erosion and thinning

Continuous ion bombardment and chemical attack slowly consume the silicon, thinning the part and opening up the cathode-to-wafer gap. As thickness drifts, RF coupling and centre etch rate shift, eventually moving the process outside its control limits and triggering replacement.

Cracking and thermal fatigue

Repeated thermal cycling, mechanical clamping stress and the inherent brittleness of silicon can produce micro-cracks that grow into through-cracks or chips. A cracked inner cathode is a serious particle source and can disturb the RF path, so it warrants immediate removal from service.

Surface roughening and deposition

Over time the silicon surface roughens and accumulates polymer or by-product films. This changes local emissivity, erosion behaviour and field uniformity, and once the deposits begin to flake they release particles onto the wafer, marking the end of useful service life.

Installation and replacement guidance

Inner cathode replacement is a precision, contamination-sensitive task performed during scheduled preventive maintenance by trained personnel following the relevant TEL procedures. The general sequence is:

• Vent the chamber and follow full lockout/tagout and RF-safety procedures before opening the lid and exposing the cathode stack.
• Remove the wafer, electrostatic chuck cover and any surrounding rings or hardware needed to access the inner cathode, keeping fasteners organised for refit.
• Carefully lift out the worn inner cathode, noting its orientation and recording erosion or crack observations for trend tracking.
• Clean the mounting interface and inspect mating surfaces, contact areas and any thermal/RF interface materials for damage or residue.
• Handle the new silicon part with clean, powder-free gloves only, seat it in the correct orientation and check it sits flat with even contact and no rocking.
• Reassemble rings and hardware to the specified torque and sequence, then close the chamber, pump down and leak-check.
• Run seasoning/conditioning recipes and re-qualify centre etch rate, uniformity and particle performance before returning the tool to production.

Spare parts strategy for TEL etch chambers

Silicon cathode consumables are replaced predictably, which makes them ideal candidates for buffer stock. Sourcing them through ESCT Fab Support gives engineering and procurement teams a dependable alternative to single-source OEM purchasing:

• Second-source new parts verified to the form, fit and function of OEM P/N 3D10-202364-12, referenced under ESCT P/N ES7099-168.
• High-purity silicon and tight dimensional control so the replacement behaves like the original in the chamber.
• A typical lead time of 4–5 weeks, supporting planned PM cycles and buffer-stock replenishment.
• An independent supply route that reduces dependence on a single channel and helps contain spares cost.
• Knowledgeable support to confirm fit against your specific chamber configuration before you order.

Frequently asked questions

What does the inner cathode actually do in the chamber?

It forms the central region of the powered lower electrode (CEL) directly beneath the wafer, coupling RF power into the plasma there and providing a sacrificial silicon surface. Its condition sets centre etch rate, plasma symmetry and particle performance across the middle of the 300 mm wafer.

Is this an original OEM part?

No. This is a second-source, new part supplied as an OEM-compatible component verified to the form, fit and function of TEL OEM P/N 3D10-202364-12. It is not an original Tokyo Electron OEM part and is offered as an independent alternative.

How often does the inner cathode need replacing?

As a sacrificial silicon consumable, its life depends on chemistry, RF power, duty cycle and your particle and uniformity limits. Most fabs track erosion and on-wafer metrics, then replace the part on a defined PM interval or when process drift indicates wear, rather than at a fixed run count.

What are the warning signs that it is worn out?

Typical indicators are a drift in centre etch rate or uniformity, rising particle counts, visible thinning, surface roughening or deposition, and any sign of cracking or chipping. A cracked silicon cathode should be removed from service immediately because of the particle and process risk.

What is the lead time and how should we stock it?

The typical lead time is 4–5 weeks. Because the part wears on a predictable schedule, most teams hold one or more units as buffer stock and replenish during planned PM windows so a worn cathode never gates tool availability.

Will it match our existing chamber and process?

It is built to the form, fit and function of the referenced OEM part, but TEL etch chambers exist in several configurations. We recommend confirming your tool and chamber details with us against OEM P/N 3D10-202364-12 before ordering so the correct inner cathode variant is supplied.

Summary

The Inner Cathode (OEM P/N 3D10-202364-12, ESCT P/N ES7099-168) is a high-purity silicon consumable forming the central section of the lower CEL electrode in TEL 300 mm plasma etch chambers. It couples RF power into the plasma under the wafer centre, acts as a sacrificial silicon surface, and directly governs centre etch uniformity, profile control and particle performance. Supplied as a second-source new part verified to OEM form, fit and function, with a 4–5 week lead time, it gives fabs a reliable, cost-effective way to keep TEL etch chambers running within specification.

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 3D10-202364-12. 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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