839-031686-001
COIL, EIGHT TURN

Eight-turn RF coil (OEM P/N 839-031686-001), inductively coupled plasma source coil for LAM etch systems

ESCT P/N ES2022-123 · LAM-compatible eight-turn induction coil, OEM repaired

The Eight-Turn RF Coil (OEM P/N 839-031686-001) is the inductive antenna element that sits at the heart of an inductively coupled plasma (ICP) source on LAM process equipment. As its name indicates, the component is a single conductor wound through eight discrete turns, forming a planar or helical spiral that is mounted above the dielectric window of the plasma chamber. When RF power is applied to the coil, the alternating current produces a time-varying magnetic field that passes through the dielectric and induces an azimuthal electric field inside the chamber, sustaining a dense, low-pressure plasma without any electrode in direct contact with the process gases.

In a transformer-coupled or inductively coupled source, the eight-turn coil effectively forms the primary winding, while the plasma itself behaves as a single-turn secondary. The turn count is not arbitrary: eight turns sets the inductance, the voltage distribution along the conductor, and the coupling efficiency between the RF generator and the plasma load. This makes the coil one of the defining elements of the source’s electrical signature, and any deviation in its geometry, conductivity or cooling directly changes how power is delivered to the wafer environment.

Because the coil operates under high RF currents, elevated temperatures and continuous thermal cycling, it is a wear-relevant part rather than a permanent fixture. A degraded or damaged coil undermines plasma stability, match tuning and process repeatability, which is why a verified, fit-for-function replacement such as ES2022-123 is an important line item in any LAM fab spares strategy.

Functional role of the eight-turn coil in LAM plasma source platforms

The coil is the energy-transfer interface between the RF subsystem and the process plasma. It does not touch the wafer or the process gas directly, but everything that happens in the chamber depends on how cleanly and consistently it couples power across the dielectric window. Its principal functions include:

• Converting RF current from the generator and matching network into a magnetic field that inductively sustains the plasma.
• Establishing the inductance and impedance that the automatic matching network must tune against to achieve minimal reflected power.
• Shaping the radial distribution of power deposition, which influences ion and radical uniformity across the wafer.
• Carrying coolant through its hollow conductor (where applicable) to remove resistive and plasma-radiated heat during continuous operation.
• Maintaining a fixed, repeatable geometry above the dielectric window so that coupling remains stable wafer-to-wafer and chamber-to-chamber.
• Providing a defined RF current return path that keeps the source’s electrical behaviour predictable and serviceable.

Electrical and signal performance

RF conduction and coupling efficiency

At RF frequencies the current flows predominantly in the outer skin of the conductor, so the coil is normally manufactured from high-conductivity copper, often plated or surface-treated to preserve a clean, low-loss surface. The eight-turn winding establishes a defined inductance and self-resonance, and the quality of every joint, plating layer and bend determines how much of the delivered power reaches the plasma rather than being dissipated as heat in the coil itself.

• High-conductivity copper conductor sized to handle substantial circulating RF current with low resistive loss.
• Eight-turn geometry that fixes the inductance and the voltage gradient along the winding.
• Clean, low-resistance terminations to preserve match-network tuning range and stability.
• Surface finish chosen to limit skin-effect losses and resist oxidation over service life.

Thermal management and stability

Sustained RF operation heats the coil through both resistive (I²R) losses and radiant load from the plasma. Many designs route deionised cooling water through the hollow conductor to hold the winding at a stable temperature. Effective cooling keeps the conductor resistivity and dimensions stable, which in turn keeps the inductance and coupling constant from the first wafer of a lot to the last.

• Internal coolant passage (where fitted) to extract resistive and radiated heat.
• Dimensional stability under thermal cycling to keep coupling geometry fixed.
• Leak-tight fluid fittings that protect against coolant ingress near energised RF surfaces.
• Consistent temperature operation to minimise drift in inductance and matched power.

Impact on tool performance and yield

Because the coil governs how RF energy enters the plasma, its condition propagates directly into process results. A coil that has drifted out of specification, developed a poor joint or partially lost cooling will undermine the very parameters that define a healthy etch or deposition process:

• Loss of plasma stability, manifesting as flicker, dropout or difficulty striking the plasma.
• High or fluctuating reflected power as the matching network struggles to tune a shifting load.
• Etch- or deposition-rate drift and non-uniformity across the wafer surface.
• Increased wafer-to-wafer and chamber-to-chamber variation, eroding process repeatability.
• Unplanned downtime and scrapped wafers when a coil fails mid-lot.
• Accelerated wear of associated RF components when power is delivered inefficiently.

Common failure modes

Resistive heating and hot-spot damage

A high-resistance joint, localised plating loss or restricted coolant flow concentrates heat at a single point on the winding. The resulting hot spot raises local resistivity, discolours and degrades the conductor surface, and can ultimately deform the turn, shifting the coil’s inductance away from the value the matching network expects.

Corrosion, erosion and surface degradation

Over many process hours the coil surface can oxidise or pit, particularly where plating has worn through. Because RF current travels in the conductor skin, even thin surface degradation raises losses, lowers coupling efficiency and forces more delivered power to achieve the same plasma density.

Coolant leaks and cracking

Repeated thermal cycling fatigues the conductor and its fluid connections. Cracks at bends or fittings can leak coolant near energised RF surfaces, causing arcing, intermittent operation and potential damage to the dielectric window and surrounding hardware if not caught early.

Installation and replacement guidance

Replacing the eight-turn coil should be carried out by qualified service technicians following LAM’s documented procedures for the specific tool. The outline below summarises the typical sequence; always defer to the OEM service manual and your site safety protocols:

• Place the tool in a safe service state, lock out and tag out RF power, and confirm zero energy at the coil terminals before any contact.
• Isolate, drain and depressurise the coolant circuit feeding the coil, capturing any residual fluid.
• Remove access covers and the RF shield, then disconnect the coil’s RF terminations and coolant fittings, noting their orientation.
• Lift out the worn coil without contacting or scratching the dielectric window, and inspect the window and mounting surfaces for residue or damage.
• Fit ES2022-123, with correct turn alignment, standoff height and seating so the coupling geometry matches the original specification.
• Reconnect RF terminations to specified torque and remake coolant fittings, then leak-check the cooling circuit before restoring power.
• Restore RF power, verify a clean match with low reflected power, and qualify the chamber with the relevant process and uniformity checks before returning to production.

Spare parts strategy for LAM plasma source hardware

RF source coils are exactly the kind of high-impact, wear-relevant component that benefits from a planned spares programme rather than reactive sourcing. Holding a verified eight-turn coil on the shelf shortens recovery time when a source goes out of specification, and ESCT Fab Support helps fabs manage that risk:

• Cross-reference clarity between OEM P/N 839-031686-001 and ESCT P/N ES2022-123 for confident ordering.
• Parts verified to the original form, fit and function so the coil drops into the existing source without redesign.
• A typical lead time of around 5 weeks, allowing maintenance and inventory teams to plan replacements ahead of need.
• A cost-effective alternative to original OEM pricing for a critical RF consumable.
• Support in building a balanced spares pool around the plasma source to minimise mean time to recovery.

Frequently asked questions

What does the eight-turn coil actually do?

It is the inductive antenna of an inductively coupled plasma source. RF current flowing through its eight turns generates a magnetic field that passes through the dielectric window and induces the electric field that sustains the plasma inside the chamber, without any electrode contacting the process gas.

Is this an original LAM OEM part?

No. ES2022-123 is supplied as an OEM-repaired, reconditioned coil that is verified to the form, fit and function of OEM P/N 839-031686-001. It is offered as a compatible service part and is not an original OEM component, nor is ESCT Fab Support affiliated with or endorsed by the OEM.

Why does the number of turns matter?

The eight-turn count fixes the coil’s inductance, its voltage distribution and how efficiently it couples power into the plasma. Using a coil with the correct turn geometry lets the matching network tune as designed and that power deposition and uniformity match the original source behaviour.

How do I know when the coil needs replacing?

Typical indicators include rising or unstable reflected power, difficulty striking or holding the plasma, visible discolouration or hot-spot damage on the winding, coolant leaks, and drift in etch or deposition rate and uniformity that cannot be corrected by routine tuning.

Does the coil require cooling?

Designs of this type commonly route coolant through the hollow conductor to remove resistive and plasma-radiated heat. Where a cooling circuit is present, it must be properly connected and leak-checked on installation to maintain stable inductance and protect the surrounding RF hardware.

What is the lead time for ES2022-123?

The typical lead time is approximately 5 weeks. Planning replacement coils into your spares inventory ahead of this window helps avoid extended source downtime when a coil reaches the end of its service life.

Summary

The Eight-Turn RF Coil (OEM P/N 839-031686-001, ESCT P/N ES2022-123) is the inductive source coil that couples RF power into the plasma of a LAM ICP etch or deposition chamber. Its eight-turn copper winding defines the source inductance, coupling efficiency and power uniformity, making it central to plasma stability, match tuning and yield. Subject to resistive heating, surface degradation and coolant-related fatigue, it is a wear-relevant component best managed through a planned spares strategy. ESCT Fab Support supplies an OEM-repaired coil verified to original form, fit and function, with clear cross-referencing and a typical 5-week lead time, as a cost-effective alternative for keeping LAM plasma sources in qualified production.

Disclaimer: This part is supplied by ESCT Fab Support as a reconditioned, OEM-compatible component, verified to the form, fit and function of Lam Research part number 839-031686-001. 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.