718-094756-081
ELCTD,CAP,GD RING,ESC,8IN NCH

Electrode cap ground ring for electrostatic chuck (OEM P/N 718-094756-081), 200mm ESC ground return component for LAM etch systems

ESCT P/N ES2022-121 | LAM-compatible electrode cap ground ring for 8-inch (200mm) electrostatic chuck assemblies

The Electrode Cap Ground Ring is a precision annular component that seats around the periphery of an electrostatic chuck (ESC) electrode cap in LAM plasma etch chambers configured for 8-inch (200mm) wafers. Carrying the OEM part number 718-094756-081 and supplied by ESCT Fab Support as ES2022-121, it forms part of the chuck stack that supports, clamps and grounds the wafer during reactive-ion and conductor etch processes. The “NCH” descriptor in the original part name denotes the notch feature machined into the ring to align with the wafer notch and the chuck’s keyed orientation, giving repeatable angular placement on every cycle.

Within the ESC assembly, the ground ring sits at the boundary between the clamped wafer and the surrounding chamber hardware. It defines the electrical edge of the chuck, completing the RF and DC ground return path while shaping the plasma sheath at the wafer perimeter. Because it lives directly in the plasma and in contact with corrosive process chemistries, it is a consumable that wears, erodes and eventually requires planned replacement to keep edge etch behaviour inside specification.

Although the component looks simple, its geometry, surface finish and material grade have a direct influence on edge yield, particle performance and clamping reliability. A worn or contaminated ground ring is a common, and frequently overlooked, root cause of edge-zone non-uniformity and intermittent dechucking faults on mature 200mm LAM platforms.

Functional role of the electrode cap ground ring in LAM etch platforms

The ground ring performs several interdependent jobs simultaneously, spanning electrical, mechanical and plasma-control functions. In a tightly packaged ESC stack, a single ring delivers the following:

• Completes the RF and DC ground return at the wafer edge, anchoring the plasma sheath and stabilising the local potential reference for the etch field.
• Defines the electrical and physical periphery of the electrode cap, masking the chuck edge from direct plasma attack and confining the active etch area to the wafer.
• Shapes the sheath profile across the outer few millimetres of the wafer, governing ion-trajectory angle and therefore edge etch rate and profile.
• Provides the notch-keyed orientation feature that registers wafer-notch position to the chuck, supporting repeatable edge alignment between runs.
• Acts as a sacrificial barrier that protects the higher-value electrode cap and ESC ceramic from erosion, extending the service life of the underlying assembly.
• Contributes to edge thermal and gas-conductance conditions by setting the gap and seating geometry around the wafer perimeter.

Material and process performance

As a plasma-facing consumable, the electrode cap ground ring lives or dies by its material grade and surface condition. Two performance domains dominate its design and selection.

Plasma and chemical resistance

Ground rings of this class are produced in plasma-durable materials selected to match the chamber’s etch chemistry, typically high-purity alumina or quartz for dielectric grounding behaviour, or anodised aluminium and conductive ceramic where a low-resistance return path is required. The grade must withstand fluorine-, chlorine- and bromine-based plasmas at elevated bias without excessive sputter erosion.

• High-purity feedstock minimises mobile-ion and metallic contamination that could transfer to the wafer edge.
• Resistance to halogen attack limits the formation of friable corrosion products that shed as particles.
• Stable bulk resistivity keeps the ground return consistent as the ring ages and surface stoichiometry shifts.

Dimensional and surface integrity

Form, fit and function depend on tight control of inner and outer diameters, ring height, flatness and the notch feature. Seating-face finish governs both electrical contact quality and particle generation, so the surface is machined and treated to a controlled roughness.

• Concentricity to the electrode cap keeps the sheath symmetric and edge etch rotationally uniform.
• A controlled seating finish gives repeatable contact resistance to the grounded chuck body.
• A correctly profiled notch preserves wafer-to-chuck registration and prevents mechanical interference during handling.

Impact on tool performance and yield

Because it occupies the most yield-sensitive region of the wafer, the condition of the ground ring propagates directly into device-level results at the edge. The practical consequences of degradation include:

• Edge-zone etch-rate drift and profile tilt as the ring erodes and the sheath reshapes.
• Rising particle counts and edge defectivity from sputtered or flaking ring material.
• Inconsistent RF grounding that manifests as reflected-power instability or impedance-match drift.
• Wider wafer-to-wafer and chamber-to-chamber variation, undermining matched-tool strategies.
• Edge-exclusion loss, reducing the number of saleable die per 200mm wafer.

Common wear and failure modes

The ground ring degrades through predictable mechanisms that a good PM regime tracks and replaces ahead of failure.

Plasma erosion and recession

Continuous ion bombardment thins the exposed surfaces and recedes sharp edges over time. As the profile rounds, the sheath geometry at the wafer perimeter changes, shifting edge etch behaviour gradually until it crosses the process control limit.

Particle generation and surface cracking

Repeated thermal cycling combined with chemical attack can produce micro-cracks, glazing or flaking of corrosion by-products. These shed onto the wafer edge and into the chamber, driving defectivity excursions that are often misattributed to other hardware before the ring is inspected.

Grounding degradation and seating faults

Oxidation, residue build-up or a warped seating face raises contact resistance in the ground return path. The result can be intermittent RF grounding, dechucking difficulty or match-network instability, which is why seating surfaces should be cleaned and inspected at every ring change.

Installation and replacement guidance

Replacement should follow the relevant LAM maintenance procedure for the specific chamber and chuck revision. The general sequence is as follows:

• Vent the chamber, lock out RF and gas, and allow the ESC stack to reach a safe handling temperature.
• Remove any retaining hardware and lift the worn ground ring clear, noting the notch orientation before extraction.
• Inspect the electrode cap, chuck seating face and ground contact for residue, erosion or damage, and clean per spec using approved solvents and lint-free wipes.
• Handle the new ring with clean, powder-free gloves only; avoid contact with the plasma-facing surfaces and confirm there is no shipping debris.
• Seat the replacement ring with the notch correctly registered to the chuck key, checking it is fully home and flat with no rock or gap.
• Reinstall retaining hardware to the specified torque and verify ground continuity to the chuck body.
• Pump down, leak-check, run a season or burn-in recipe, and confirm edge etch performance and particle counts before returning the tool to production.

Spare parts strategy for LAM ESC consumables

Edge consumables such as the electrode cap ground ring are scheduled-replacement items, so keeping qualified stock on hand protects uptime on ageing 200mm LAM fleets. Sourcing through ESCT Fab Support offers:

• Parts verified to the original form, fit and function of OEM P/N 718-094756-081.
• Cross-reference under ESCT P/N ES2022-121 for straightforward reordering and inventory control.
• A practical 4-week lead time that supports planned PM scheduling and buffer stocking.
• A cost-effective alternative to OEM pricing for legacy 8-inch process tools.
• Support for matched-chamber strategies through consistent dimensional and material quality.

Frequently asked questions

What does this part do in the etch chamber?

It is the ground ring fitted around the electrode cap of a 200mm electrostatic chuck. It completes the RF and DC ground return at the wafer edge, shapes the plasma sheath around the wafer perimeter, and protects the underlying electrode cap and ceramic from plasma erosion.

Is this an original LAM OEM part?

No. It is supplied as a new, OEM-compatible part verified to the form, fit and function of LAM OEM P/N 718-094756-081. It is not an original OEM-branded component, but it is built and inspected to perform as a direct functional equivalent.

Which wafer size and tool family does it suit?

It is configured for 8-inch (200mm) wafers on LAM plasma etch platforms that use an electrostatic chuck with a notched ground ring. Always confirm the chamber and chuck revision against the OEM and ESCT part numbers before fitting.

How often should the ground ring be replaced?

Replacement interval depends on process chemistry, RF power and run hours, so it is governed by your accumulated-RF-hours or wafer-count PM trigger. Many fabs change it on the same cadence as other edge consumables, and inspect it whenever edge uniformity or particle counts begin to drift.

What is the lead time and how do I reorder?

The standard lead time is 4 weeks. Reorder using ESCT P/N ES2022-121, which cross-references to LAM OEM P/N 718-094756-081, so you receive the correct 200mm notched ground ring every time.

What are the signs that a worn ring is affecting yield?

Typical symptoms include creeping edge etch-rate or profile drift, rising edge-zone particle and defect counts, and intermittent RF grounding or dechucking faults. When edge performance degrades and other hardware checks out, the ground ring is a prime suspect.

Summary

The Electrode Cap Ground Ring (OEM P/N 718-094756-081, ESCT P/N ES2022-121) is a plasma-facing edge consumable for 8-inch (200mm) electrostatic chucks on LAM etch tools. It completes the ground return, shapes the edge sheath, registers wafer orientation through its notch, and shields the electrode cap from erosion. Because it sits in the most yield-critical region of the wafer, keeping a verified replacement in stock and changing it on a disciplined PM schedule is one of the most direct ways to protect edge yield, particle performance and clamping reliability on legacy 200mm LAM platforms.

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 718-094756-081. 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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