839-021113-002
SI INNER ELECTRODE

Silicon inner electrode (OEM P/N 839-021113-002), inner silicon cathode for LAM 300 mm plasma etch systems

ESCT P/N ES2099-023, high-purity silicon inner electrode (cathode) for capacitively coupled plasma etch chambers

The Silicon Inner Electrode is a high-purity silicon cathode component used in LAM capacitively coupled plasma (CCP) etch chambers configured for 300 mm wafer processing. Positioned at the inner region of the powered or grounded electrode assembly, this part forms part of the silicon surface that directly faces the plasma sheath above the wafer. As a sacrificial silicon member, it is engineered both to carry RF current and to participate in the surface chemistry of the discharge, contributing fluorine and silicon-bearing species that help stabilise etch rate and selectivity across the wafer.

In a typical etch chamber the electrode stack is segmented into inner and outer (or edge) zones so that plasma density, voltage and consumption can be tuned independently from the centre of the wafer outward. The inner electrode covers the central footprint of the substrate, where the bulk of the device area is patterned. Because it sits directly in the path of ion bombardment and reactive fluorine and oxygen radicals, it erodes over time and must be treated as a scheduled consumable rather than a permanent structural part.

The material grade, flatness, surface finish and electrical resistivity of the inner electrode all influence centre-of-wafer etch behaviour. A correctly specified silicon inner electrode keeps the plasma uniform over the central die, maintains a clean RF return path and minimises the particle and metallic contamination that can degrade yield. ESCT supplies ES2099-023 as a form-, fit- and function-verified replacement for the LAM OEM electrode, allowing fabs to maintain process continuity without committing to single-source OEM lead times.

Functional role of the silicon inner electrode in LAM plasma etch platforms

The inner electrode is simultaneously an electrical, chemical and thermal interface between the chamber hardware and the plasma. Its silicon construction is deliberate: silicon participates in the discharge chemistry in a way metal electrodes cannot, and it does so without introducing metallic contamination onto the wafer. Its principal functions include:

• Presenting a conductive silicon surface to the plasma over the central wafer region, completing the capacitive RF circuit between the generator and the discharge.
• Acting as a controlled silicon source, releasing silicon and consuming free fluorine in fluorocarbon chemistries to help regulate the fluorine-to-carbon ratio that governs etch selectivity.
• Shaping the electric field and plasma sheath above the centre of the wafer to balance ion energy and ion flux against the edge zone.
• Providing a defined, low-contamination return path for RF current so that impedance remains stable as the chamber cycles.
• Maintaining a consistent, mountable interface to the electrode backing structure so that thermal contact and clamping force are repeatable across replacements.
• Sacrificially absorbing ion bombardment so that the more costly permanent electrode and chamber hardware behind it are protected from erosion.

Material and process performance

Silicon purity and contamination control

The inner electrode is manufactured from high-purity silicon with tightly controlled bulk and trace-metal content. Because the silicon surface is continuously sputtered and etched during processing, any metallic impurity in the bulk material can be liberated directly into the plasma and transported onto the wafer, where it threatens gate integrity and junction performance. Purity is therefore not a cosmetic specification but a yield-critical one.

• Low trace-metal silicon minimises the risk of mobile-ion and heavy-metal contamination of the device wafer.
• Controlled bulk resistivity keeps RF coupling and field distribution consistent with the original electrode design.
• Uniform grain structure or single-crystal grade supports an even, predictable erosion profile rather than localised pitting.
• Clean machining and packaging reduce surface particles that would otherwise add to first-wafer defect counts.

Surface finish, flatness and dimensional fidelity

Etch uniformity at the wafer centre is sensitive to the geometry of the electrode that faces it. Flatness and parallelism set the local electrode-to-wafer gap, while surface finish governs initial particle behaviour and the consistency of the erosion front. ES2099-023 is produced to match the OEM dimensional envelope so that gap, seating and electrical contact reproduce the original tool baseline.

• Tight flatness and parallelism preserve a uniform sheath and ion energy across the central die area.
• Consistent thickness maintains the designed inter-electrode capacitance and RF return characteristics.
• Controlled surface finish supports stable particle performance from the first wafer after a seasoning recipe.
• Matched mounting features give repeatable thermal contact to the backing electrode and cooling path.

Impact on tool performance and yield

As the inner electrode wears or degrades, its effects propagate directly into the most heavily patterned region of the wafer. Because the central die area usually carries the largest share of saleable product, drift here has an outsized effect on line yield. The practical consequences of a worn, contaminated or out-of-specification inner electrode include:

• Centre-to-edge etch rate and critical-dimension drift as the silicon source area and gap change with erosion.
• Loss of selectivity or profile control as the fluorine-consuming behaviour of the silicon surface shifts.
• Rising particle counts and added defect adders as the eroded surface roughens or flakes.
• Metallic contamination signatures if a low-purity or counterfeit electrode is fitted.
• RF impedance instability, reflected power and matching faults that can trip the generator or destabilise the plasma.
• Increased frequency of qualification failures, scrap and unplanned chamber downtime.

Common wear and failure modes

Erosion and thinning

The dominant failure mode is gradual erosion. Continuous ion bombardment and chemical etching of the silicon surface thin the electrode and enlarge the electrode-to-wafer gap over time. As thickness approaches its wear limit, etch rate at wafer centre drifts and uniformity degrades, signalling that the electrode has reached the end of its useful life and must be replaced before it falls out of process specification.

Cracking and thermal fracture

Silicon is brittle and intolerant of mechanical or thermal shock. Uneven clamping, debris trapped under the electrode, mishandling during installation, or steep thermal gradients during rapid power cycling can initiate cracks. A fractured electrode disturbs the RF path, becomes a major particle source and, in severe cases, can cause arcing that damages neighbouring chamber hardware.

Surface roughening, deposition and arcing

Polymer deposition, localised hot spots and non-uniform erosion can roughen the silicon face and create high-field points. These promote micro-arcing, which leaves pits and burn marks, raises particle generation and accelerates further degradation. Poor electrical or thermal contact at the mounting interface aggravates this by concentrating current and heat, shortening electrode life and destabilising the process.

Installation and replacement guidance

Inner electrode replacement is a wet-bench-clean, particle-sensitive procedure that should follow the tool owner’s approved maintenance procedure and be carried out only by trained personnel. The following sequence outlines good practice:

• Isolate the chamber: shut off RF and gas supplies, vent to atmosphere following lockout/tagout, and allow the chamber to cool to a safe temperature.
• Open the chamber under cleanroom discipline and remove the worn electrode, noting its orientation and the condition of adjacent rings and the backing electrode.
• Inspect and clean the mounting surface and contact features, removing polymer residue and debris that would impair seating, thermal contact or the RF path.
• Unpack ES2099-023 with clean, powder-free gloves, handling only by permitted areas; inspect for chips or cracks and confirm dimensional match before fitting.
• Seat the new electrode in the correct orientation and tighten any fasteners or clamps evenly to the specified torque to avoid point loading and stress fracture.
• Reassemble the chamber, pump down, leak-check and confirm RF matching and reflected power are within limits before processing wafers.
• Run the prescribed seasoning or conditioning recipe, then verify etch rate, uniformity and particle counts against the qualification baseline before returning the tool to production.

Spare parts strategy for LAM etch consumables

Silicon inner electrodes are recurring consumables, so securing a dependable supply is central to keeping etch tools productive and cost-effective. ESCT supports fabs with a sourcing strategy built around availability, verified quality and predictable lead times:

• Second-source, new parts verified to the OEM form, fit and function, reducing dependence on a single supply channel.
• Competitive pricing on a high-turn consumable, improving cost-per-wafer without compromising process integrity.
• A typical lead time of 4-5 weeks, supporting planned preventive maintenance scheduling and buffer-stock policies.
• High-purity silicon to protect against metallic and particle contamination of device wafers.
• Dimensional and electrical matching to preserve etch uniformity, RF behaviour and tool qualification baselines.
• Technical support to confirm applicability and assist with consumable-management planning across multiple chambers.

Frequently asked questions

What does the silicon inner electrode actually do in the chamber?

It is the silicon cathode surface that faces the plasma over the centre of the wafer. It carries RF current, helps shape the plasma sheath and acts as a controlled silicon source that consumes free fluorine, stabilising etch rate, selectivity and uniformity across the central die area.

Is this an original LAM OEM part?

No. ES2099-023 is supplied as a new, second-source part that is OEM-compatible and verified to the form, fit and function of LAM P/N 839-021113-002. It is not an original OEM part and is not sold as one, but it is engineered to perform as a direct equivalent in the applicable chambers.

Why is silicon used instead of a metal electrode?

Silicon participates in the etch chemistry by consuming fluorine and releasing silicon species, which helps control selectivity, and it does so without introducing the metallic contamination that a metal electrode would shed onto the wafer. This makes high-purity silicon the appropriate choice for the plasma-facing cathode surface.

How do I know when the inner electrode needs replacing?

The usual indicators are drift in centre-of-wafer etch rate and uniformity, rising particle counts, visible erosion or thinning approaching the wear limit, and RF matching instability. Many fabs replace the electrode on a wafer-count or RF-hours schedule derived from monitoring data rather than waiting for an out-of-specification event.

Will fitting this part disturb my process qualification?

Because the part is matched dimensionally and electrically to the OEM electrode, it is designed to drop into the existing baseline. As with any consumable change, a seasoning recipe followed by verification of etch rate, uniformity and particle performance against your qualification standard is recommended before returning to production.

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

The typical lead time is 4-5 weeks. As a recurring consumable, it is best managed with a buffer stock sized to your replacement interval and number of chambers, so that planned maintenance is never held up waiting on supply. ESCT can advise on appropriate stocking levels.

Summary

The Silicon Inner Electrode (LAM P/N 839-021113-002, ESCT P/N ES2099-023) is a high-purity silicon cathode consumable that governs plasma behaviour, RF coupling and etch chemistry over the centre of the wafer in LAM 300 mm plasma etch chambers. Its purity, flatness and dimensional fidelity directly influence centre-of-wafer uniformity, selectivity, particle performance and yield, and it wears predictably through erosion, with cracking and arcing as secondary failure modes. Supplied as a new, second-source, OEM-compatible part with a 4-5 week lead time, ES2099-023 gives fabs a verified, cost-effective alternative for keeping etch tools qualified and in production.

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 Lam Research part number 839-021113-002. It is not an original OEM part and is not sold as one. It is not manufactured by, endorsed by, or affiliated with Lam Research, and all manufacturer names and part numbers are quoted for identification and compatibility purposes only.

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