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The focus ring is one of the most influential consumable components inside a Tokyo Electron (TEL) 300 mm plasma etch chamber. It is the annular part that surrounds the wafer directly, sitting concentrically on the electrostatic chuck (ESC) periphery so that its inner bore frames the 300 mm wafer edge. In a process where the plasma sheath wants to bend and terminate abruptly at the wafer perimeter, the focus ring extends the wafer surface electrically and physically, presenting a continuation of the process surface so that the sheath remains flat and parallel out to and slightly beyond the outermost dies.
Identified by OEM part number 3D10-250899-11 and supplied by ESCT Fab Support under part number ES7099-167, this ring is a directly exposed chamber consumable. It lives in the harshest part of the reactor, fully immersed in the bulk plasma, bombarded by energetic ions, and subjected to the same fluorocarbon, oxygen and halogen chemistries that etch the wafer itself. Because it is sacrificial by design, its dimensions and surface condition drift over time, and that drift is felt directly in edge-region critical dimension (CD), etch rate and profile angle.
In practical terms, a focus ring is the single cheapest lever an engineer has over edge yield. Replacing it on schedule keeps the last few millimetres of every wafer inside specification, which on a 300 mm substrate can represent dozens of saleable dies per wafer. Allowing it to over-erode quietly erases that yield without any obvious alarm, which is why ring management is a core part of TEL etch fleet maintenance.
The focus ring is not a passive spacer. It is an active part of the RF and plasma topology of the chamber, and its job is to make the wafer edge behave electrically like the wafer centre. Its principal functions include the following.
Focus rings for TEL etch chambers are manufactured from high-purity, plasma-grade materials selected to balance erosion resistance, electrical behaviour and particle cleanliness. The exact material is matched to the process the ring serves, but the performance considerations fall into two clear groups.
Common constructions use high-resistivity silicon, silicon carbide (SiC) or high-purity quartz, each chosen because it resists the aggressive fluorocarbon and halogen chemistries while contributing minimal contamination to the wafer.
Because the ring sets a boundary condition, its as-built geometry must reproduce the OEM design closely; small departures in inner-bore diameter, height or step profile shift the sheath at the wafer edge.
Because the focus ring governs the last few millimetres of every wafer, its condition translates almost directly into edge yield. The consequences of an out-of-spec or worn ring include the following.
As a directly exposed consumable, the focus ring fails predictably through plasma erosion, but several distinct mechanisms drive it out of service.
The dominant wear mode is gradual thinning under ion bombardment, particularly at the inner edge nearest the wafer. As the ring loses height, the sheath at the wafer perimeter drops and edge etch behaviour drifts; once erosion exceeds the recipe-qualified limit the ring must be replaced regardless of its visual appearance.
Thermal cycling and mechanical stress can initiate cracks, while localised erosion can cause flakes to spall from the surface. Both generate particles that land on the wafer edge as killer defects and can, in severe cases, leave debris in the chamber that affects subsequent runs.
A worn, contaminated or poorly seated ring can disturb the local RF return path and trigger micro-arcing at the wafer edge. Arc events pit the ring surface, create particles and can damage the wafer and adjacent hardware, making them an urgent reason to remove a suspect ring from service.
Focus ring replacement is a routine but precision task that should be carried out by trained technicians following the relevant TEL maintenance procedure, in a clean environment with appropriate gloves and handling tools. The following ordered steps describe the typical sequence.
Focus rings are high-turnover consumables, so sourcing them reliably and cost-effectively has a direct effect on cost of ownership and tool availability. ESCT Fab Support helps fabs keep their TEL etch fleets running with the following advantages.
It surrounds the 300 mm wafer on the electrostatic chuck and extends the process surface beyond the wafer edge, keeping the plasma sheath flat and ion trajectories vertical at the perimeter so that edge etch rate, critical dimension and profile match the rest of the wafer.
No. This ring is supplied as a second-source new, OEM-compatible part. It is verified to match the original to form, fit and function under OEM P/N 3D10-250899-11, but it is not an original Tokyo Electron OEM component and is not sold as such.
Focus rings of this type are made from high-purity, plasma-grade materials such as silicon, silicon carbide or quartz, selected for erosion resistance, controlled electrical resistivity and low particle generation. The material is matched to the process the ring serves.
Replacement is normally driven by accumulated RF or process hours, by erosion or height loss reaching the recipe-qualified limit, or by signs of drifting edge yield, rising particle counts or arcing. Most fabs track ring life with a counter and replace on a planned interval before performance degrades.
The typical lead time is 4-5 weeks. Because focus rings are steady, high-turnover consumables, we recommend ordering against a forecast and holding buffer stock so chambers are never held up waiting for a replacement ring.
The ring is built to reproduce the OEM geometry and material characteristics so it behaves as the qualified part does. As with any consumable change, we recommend running your standard conditioning and edge-performance verification after installation before returning the chamber to full production.
The focus ring (OEM P/N 3D10-250899-11, ESCT P/N ES7099-167) is a critical edge-control consumable for Tokyo Electron 300 mm plasma etch chambers. By extending the process surface and shaping the plasma sheath at the wafer perimeter, it protects edge critical dimension, profile and uniformity, and therefore edge yield, across the entire fleet. As a sacrificial part it erodes predictably and must be replaced on schedule to keep the last few millimetres of every wafer in specification. Supplied by ESCT Fab Support as a second-source new part with controlled material quality, clear cross-referencing and a 4-5 week lead time, it offers a cost-effective, dependable way to keep TEL etch tools running at full yield.
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 3D10-250899-11. 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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