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The LAM 8″ flatted focus ring (OEM P/N 716-330504-081) is an annular consumable that seats around the perimeter of the electrostatic chuck (ESC) in a LAM Research plasma etch process module. Sized for 200 mm (8″) wafer handling, it surrounds the wafer edge and forms part of the radio-frequency (RF) return and ground path implied by its “GD R” designation. The flatted profile on its outer diameter provides a keyed reference feature so the ring drops into a single, repeatable rotational orientation against the chuck and surrounding hardware.
In a capacitively coupled etch chamber, the focus ring sits in one of the most aggressive locations in the entire tool: directly at the boundary between the biased wafer and the grounded chamber walls. Its job is to extend the plasma sheath outward beyond the silicon, so that the electric field lines bending near the wafer edge are corrected and the ion trajectories arriving at the outermost dies stay as vertical as they are across the wafer centre. Without a correctly conditioned ring, edge-of-wafer etch results drift away from the rest of the population.
Because it is consumed sacrificially by ion bombardment and reactive chemistry, the focus ring is a scheduled-replacement item rather than a permanent fixture. Maintaining a qualified supply of rings such as ES2022-122 directly governs how tightly a fab can hold edge-die yield and how predictably it can plan preventive maintenance (PM) windows.
The focus ring is far more than a mechanical spacer around the wafer. It actively shapes the plasma at the wafer edge while simultaneously protecting the chuck hardware and helping define the RF environment. In a LAM etch module the ring performs several interlocking functions:
A focus ring lives or dies on its material behaviour under continuous ion bombardment and reactive plasma chemistry. The ring must hold dimensional stability, resist erosion and minimise the particles and metallic contamination it introduces to the wafer edge.
Focus rings for plasma etch are typically produced from high-purity silicon, silicon carbide or quartz depending on the process chemistry; the surface erodes gradually as ions sputter material away. The grade and purity of the consumable determine how slowly the ring thins and how cleanly it does so. A ring that erodes evenly preserves sheath geometry for a longer service interval, while one that pits or spalls shifts the edge field and shortens usable life. The keyed flatted profile must remain dimensionally true so the seating reference does not shift as the upper surface recedes.
Because the ring sits within millimetres of product silicon, any metallic impurity or particle it sheds lands squarely on edge dies. High material purity minimises trace-metal contamination, while a controlled surface finish minimises particle generation as the ring is sputtered. Consistent material specification from lot to lot therefore has to hold: an out-of-spec ring can pass a visual check yet still degrade defectivity numbers at the wafer edge.
Because the focus ring directly governs the etch environment at the wafer edge, its condition propagates straight through to measurable device and tool metrics:
The primary, expected failure mode is steady erosion: ion bombardment sputters the upper surface away over thousands of RF-hours until the ring thins past its usable window. As the surface recedes, the sheath geometry at the wafer edge changes and edge-die etch results drift, signalling that the consumable has reached end of life and must be replaced.
Thermal cycling between plasma-on and plasma-off states, combined with handling during PM, can crack or chip a ceramic or silicon ring, particularly around the keyed flat. Cracks compromise the seating reference and the electrical path, and liberated fragments become large-particle defect sources. Any visible crack or chip is cause for immediate replacement.
If the flatted feature is not aligned to its keyed reference, the ring sits proud or off-centre, distorting the sheath and degrading the ground return. Polymer build-up and redeposited films on the ring surface can likewise alter the local electrical and thermal boundary, mimicking erosion symptoms even before the ring is physically worn out.
Focus ring replacement is a routine PM activity, but it must be carried out with clean-handling discipline to avoid trading a worn ring for a contaminated one. The following sequence reflects general good practice for a LAM ESC focus ring:
Focus rings are scheduled consumables, which means their availability, not just their unit cost, drives fab economics. A short-supply ring can force a chamber to run on an over-eroded part, sacrificing edge yield, or sit idle waiting for stock. Sourcing through ESCT Fab Support gives engineering and procurement teams several advantages:
It surrounds the 200 mm wafer at the edge of the electrostatic chuck and extends the plasma sheath outward past the silicon, correcting the field distortion that would otherwise tilt ion trajectories at the wafer perimeter. This keeps edge-die etch profiles consistent with the rest of the wafer while also forming part of the ground-return path.
No. ES2022-122 is supplied as a new, OEM-compatible focus ring that cross-references to LAM OEM P/N 716-330504-081. It is verified to match the original part in form, fit and function, but it is not an original LAM-branded component.
The flatted feature is a machined flat on the ring’s outer diameter that acts as a keyed orientation reference. It means the ring can only seat in one correct rotational position against the chuck, giving repeatable concentricity and a consistent ground-return contact each time the part is installed.
The usual indicators are drifting edge-die critical dimensions or profile angles, rising edge-zone defectivity, and visible thinning, pitting or cracking at PM inspection. Most fabs replace focus rings on a fixed RF-hour or wafer-count schedule derived from these trends rather than waiting for an out-of-spec excursion.
The standard lead time is six weeks. Because the focus ring is a scheduled consumable, we recommend factoring this into your buffer-stock and PM-planning cycle so that a qualified ring is always on the shelf ahead of the next service window.
Indirectly, yes. The ring partly shields the chuck periphery from ion bombardment, so an over-eroded or cracked ring exposes the more costly ESC assembly to direct attack and contamination. Replacing the ring on schedule protects the chuck and preserves the chamber’s electrical and thermal baseline.
The LAM 8″ flatted focus ring with ground return (OEM P/N 716-330504-081, ESCT P/N ES2022-122) is a sacrificial edge-confinement consumable for 200 mm LAM plasma etch chambers. Seated around the electrostatic chuck, it shapes the plasma sheath at the wafer edge, corrects ion-trajectory bending, contributes to the RF ground-return path and shields the chuck from erosion. Its keyed flatted feature gives single-orientation, repeatable installation. As an erosion-driven consumable, its condition feeds directly into edge-die yield, defectivity and PM cadence, making a reliably supplied, correctly specified replacement central to stable etch performance.
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 716-330504-081. 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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