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The focus ring carrying OEM part number D103-24221A is a precision annular consumable used in Tokyo Electron (TEL) 300 mm plasma etch process chambers. It is the sacrificial ring that surrounds the production wafer at the outer edge of the electrostatic chuck, sitting flush against the wafer perimeter so that the plasma sheath behaves as though it extends past the silicon. In doing so it converts a hard physical boundary, the edge of a 300 mm wafer, into a smooth electrical and chemical transition, which is precisely where etch processes are most difficult to control.
In a TEL etch chamber the focus ring forms part of the cathode stack at wafer level, concentric with the chuck and the surrounding insulator and cover ring assembly. It is directly exposed to ion bombardment, reactive radicals and elevated wafer-edge temperatures, which means it is a managed-wear item rather than a fixed structural component. As the ring erodes it changes the geometry that shapes the plasma at the wafer edge, so its condition has a measurable and continuous effect on edge die yield.
Because it works at the boundary between the wafer and the chamber hardware, the focus ring matters out of all proportion to its size. A worn or incorrectly seated ring can quietly cost a fab its outermost rings of die long before any obvious fault is flagged, which is why fabs treat this part as a scheduled-replacement consumable with a controlled supply chain behind it.
The focus ring performs several intertwined jobs at the same time. It is simultaneously a plasma-shaping element, a thermal extension of the wafer edge and a sacrificial barrier that protects more expensive hardware beneath it. Its principal functions in a TEL 300 mm chamber include the following.
Focus rings for TEL 300 mm etch chambers are made from high-purity, plasma-resistant materials selected to match the process chemistry and to erode in a predictable, particle-clean way. The exact grade is application dependent and should follow the recipe and tool configuration the ring is qualified for.
Depending on the etch application, focus rings in this position are commonly manufactured from high-purity silicon, silicon carbide or process-matched fine ceramics such as quartz or alumina. The material is chosen for chemical inertness to the reactive species in use, controlled electrical behaviour and the right erosion characteristics under ion bombardment.
Etch-edge performance is acutely sensitive to geometry, so the ring is held to tight tolerances on inner and outer diameter, height, flatness and the step that interfaces with the wafer. Surface finish and edge condition are equally important, because both feed directly into plasma uniformity and particle behaviour.
Because the focus ring governs the electrical and chemical environment at the wafer edge, its condition propagates directly into device results. A ring that is fresh, correctly specified and properly seated keeps the outer die inside specification; a worn or wrong ring narrows the usable area of every wafer that passes through the chamber. The practical consequences include the following.
The focus ring is designed to wear, so the goal is to manage that wear and retire the ring before it degrades the process. The dominant degradation paths are described below.
Continuous ion bombardment and chemical etching gradually thin the ring and round its critical edges. As height is lost the plasma sheath sinks at the wafer perimeter, bending ion trajectories inward and degrading edge profile control. This is the normal, predictable end-of-life mechanism that drives scheduled replacement.
Thermal cycling, mechanical mishandling during installation, or localised arcing can crack or chip the ring. Damage of this kind distorts the local field, creates particle sources and can accelerate erosion at the affected point, sometimes ending a ring’s service life well before its erosion budget is used up.
As the surface erodes it can begin to shed micro-particles or develop a roughened, redeposited layer. Beyond a certain point this drives wafer-edge defectivity and contamination excursions, which often become the practical trigger for replacement even where measured height still looks acceptable.
Focus ring replacement is a routine but exacting preventive-maintenance task. Cleanliness, correct seating and proper requalification all matter, because the ring directly sets the edge process. The following sequence reflects good general practice; always defer to the tool owner’s qualified TEL procedure and current safety requirements.
Focus rings are recurring spend, so the supply chain behind them deserves the same scrutiny as the part itself. ESCT Fab Support supplies this focus ring (OEM P/N D103-24221A) as a quality-controlled alternative that lets fabs hold availability and contain cost without compromising the edge process. The advantages of sourcing through ESCT include the following.
It surrounds the wafer at the edge of the electrostatic chuck and shapes the plasma sheath so that ion trajectories stay vertical out to the wafer rim. This protects edge feature profiles and critical dimensions, while also acting as a thermal buffer and a sacrificial shield for the chuck beneath it.
No. This focus ring is supplied as a second-source new part that is OEM-compatible and verified to the form, fit and function of OEM P/N D103-24221A. It is not an original OEM part and is not sold as one; it is a quality-controlled alternative intended as a direct functional replacement.
Replacement interval depends on the etch chemistry, RF power, run hours and how tightly edge yield is controlled, so it is set by each fab’s own data rather than a fixed figure. Rings are typically retired on a preventive-maintenance schedule tied to measured height loss, edge uniformity drift or rising particle counts.
Focus rings in this position are made from high-purity, plasma-resistant materials such as silicon, silicon carbide or process-matched fine ceramics, chosen to suit the chemistry and electrical role. The correct grade follows the qualified tool configuration, and ESCT can confirm the appropriate material against your application.
The usual indicators are a gradual shift in edge etch rate or critical dimension, degraded edge profile uniformity, and an increase in wafer-edge particle adders. Many fabs track ring height directly or use chamber qualification results, retiring the ring once any of these crosses its control limit.
The standard lead time is 4-5 weeks. Because focus rings are recurring consumables, we recommend aligning orders with planned preventive-maintenance cycles and holding appropriate buffer stock so that chamber availability is never gated by ring supply.
The focus ring (OEM P/N D103-24221A) is a yield-critical edge consumable for Tokyo Electron 300 mm plasma etch chambers. It shapes the plasma sheath, conditions the wafer-edge temperature and RF termination, and shields the chuck below it, all while wearing predictably under ion bombardment. Keeping a correctly specified, well-seated ring in service protects edge die yield and process repeatability, and ESCT Fab Support supplies this ring as a cost-effective, specification-controlled second-source alternative with a 4-5 week lead time to keep your TEL etch chambers running to plan.
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 the original equipment manufacturer part number D103-24221A. It is not an original OEM part and is not sold as one. It is not manufactured by, endorsed by, or affiliated with the original equipment manufacturer, and all manufacturer names and part numbers are quoted for identification and compatibility purposes only.
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