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The Silicon Focus Ring is a precision-machined annular consumable that surrounds the wafer at the outer edge of the electrostatic chuck inside a Tokyo Electron (TEL) 300 mm plasma etch chamber. Manufactured from high-purity silicon, it sits concentrically around the wafer perimeter so that the boundary of the plasma sheath extends beyond the silicon edge of the wafer rather than collapsing across it. In doing so, the focus ring effectively makes the chamber treat the wafer as though it were larger than its physical 300 mm diameter, pushing the natural sheath roll-off and field distortion outward into a sacrificial part instead of onto the last few millimetres of saleable die.
Because it is exposed continuously to energetic ions and reactive fluorine- or chlorine-bearing chemistries, the focus ring is one of the fastest-eroding components in the chamber and a primary determinant of edge-die yield. Its silicon construction is deliberate: a silicon ring etches at a rate comparable to the silicon wafer it surrounds and consumes the same reactive species, so it behaves as a chemically matched extension of the wafer rather than as a foreign material that would perturb the local etch rate or contribute metallic or carbonaceous contamination.
The ESCT Fab Support part ES7099-022 is offered as a second-source replacement for TEL OEM P/N 1810-329523-11, manufactured to match the form, fit, and function of the original silicon focus ring so that engineers can maintain process performance while controlling the cost and lead time of a high-turnover consumable.
Within a TEL capacitively coupled or reactive-ion etch chamber, the focus ring performs several interdependent jobs that together govern how uniformly the outermost annulus of the wafer is processed. Its principal functions are as follows.
The choice of high-purity silicon is central to how this focus ring performs. Trace metallic impurities in the ring would be liberated under ion bombardment and could deposit onto the wafer edge, so the material is held to semiconductor-grade purity. Its etch rate is matched to monocrystalline or polysilicon wafer behaviour so the ring erodes predictably and does not starve or enrich the local fluorine or chlorine population.
Beyond chemistry, the geometry of the ring is what sets the edge electric field. The inner diameter, step height relative to the wafer plane, flatness and concentricity must all be tightly controlled, because even small deviations shift the sheath shape and tilt the ion angle at the outermost dies. A consistent surface finish also reduces preferential erosion sites that would otherwise shorten ring life and shed particles.
Because the focus ring controls the etch environment exactly where the highest-density die packing meets the steepest process gradients, its condition has an outsized effect on overall wafer yield and tool availability. A worn or out-of-spec ring shows up directly in edge metrology and in scrap counts.
The dominant wear mode is gradual erosion of the upper surface and inner edge under sustained ion bombardment. As the ring thins, its step height relative to the wafer falls, the sheath geometry shifts, and edge etch results drift out of specification. This is an expected end-of-life mechanism rather than a defect, and it is the reason focus rings are scheduled consumables tracked by RF hours or wafer count.
Silicon is hard but brittle, so thermal cycling, mechanical handling during pick-and-place, or clamping stress can initiate cracks or edge chips. A fractured ring not only alters the field locally but can release large particles onto the wafer, causing immediate and severe defect excursions. Rings should be inspected for hairline cracks at every preventive-maintenance window.
Polymer or by-product films can accumulate on the ring, and uneven erosion can roughen the silicon surface over time. Both conditions seed particle generation and can subtly change the local etch chemistry. Flaking of redeposited material is a frequent contributor to edge defects and is a strong indicator that the ring has reached the end of its useful service.
Replacing a silicon focus ring is a routine preventive-maintenance task, but because the part is brittle and contamination-sensitive it must be handled with care and seated precisely. The following sequence reflects good practice; always defer to the applicable TEL maintenance procedure for the specific chamber.
Focus rings are consumed continuously and must be replaced on a predictable schedule, which makes supply continuity as important as the part itself. Sourcing ES7099-022 through ESCT Fab Support gives fabs a dependable, cost-controlled alternative to single-source OEM procurement.
It surrounds the wafer at the chamber edge and extends the plasma sheath outward beyond the wafer perimeter. This keeps ion trajectories vertical and the etch profile uniform at the outermost dies, effectively making the plasma treat the 300 mm wafer as if it were slightly larger so that field distortion lands on the sacrificial ring instead of on saleable product.
No. ES7099-022 is supplied as a new, second-source replacement that is OEM-compatible with TEL P/N 1810-329523-11. It is manufactured to match the original part’s form, fit, and function, but it is not an original Tokyo Electron OEM component and is not sold as one.
Silicon is chosen because it etches at a rate similar to the silicon wafer and consumes the same reactive species, so it behaves as a chemically matched extension of the wafer edge. This avoids local etch-rate loading and minimises the introduction of foreign material that could contaminate edge die or alter the process.
The clearest indicators are drift in edge critical dimension or etch depth, declining centre-to-edge uniformity, rising particle counts, and the ring reaching its scheduled RF-hour or wafer-count limit. Visible erosion, height loss, surface roughening or any cracking and chipping seen during preventive maintenance are also grounds for immediate replacement.
Because it is built to the same dimensional tolerances, silicon purity and step geometry as the original, it is intended to drop in without changing the process. As with any consumable change, fabs should run their normal qualification, season and metrology checks on a test wafer before returning the chamber to production.
The typical lead time is 4-5 weeks. Because focus rings are a continuously consumed part with a predictable replacement cadence, most fabs hold buffer stock sized to their chamber count and maintenance interval, and place replenishment orders against forecast rather than waiting for stock-out.
The Silicon Focus Ring, ESCT P/N ES7099-022, is a high-purity silicon consumable that surrounds the wafer in a TEL 300 mm plasma etch chamber and shapes the plasma sheath to keep edge etching vertical and uniform. By extending the active plasma beyond the wafer edge and presenting a chemically matched, sacrificial surface, it protects edge-die yield, stabilises the discharge and absorbs the most aggressive ion bombardment in the chamber. As a continuously eroding part subject to height loss, cracking and surface roughening, it is a scheduled consumable whose timely replacement governs uniformity, particle control and tool availability. Sourced as a second-source equivalent to TEL P/N 1810-329523-11, it offers a cost-effective, dependable supply for routine preventive maintenance.
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 Tokyo Electron part number 1810-329523-11. It is not an original OEM part and is not sold as one. It is not manufactured by, endorsed by, or affiliated with Tokyo Electron, and all manufacturer names and part numbers are quoted for identification and compatibility purposes only.
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