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The Silicon Focus Ring (Toshiba OEM P/N 0200-35623) is a high-purity, single-crystal or polysilicon annular consumable that surrounds the 300 mm wafer on the electrostatic chuck inside a plasma etch process chamber. It sits flush against the outer edge of the wafer, bridging the discontinuity between the silicon substrate and the surrounding chamber hardware so that the plasma sheath and electric field “see” a continuous silicon surface extending beyond the wafer perimeter. In doing so it extends the active process region outward, allowing the dies at the extreme edge of the wafer to be etched under conditions close to those experienced at the wafer centre.
Within a Toshiba-supplied plasma etch chamber, the focus ring is one of the most exposed and shortest-lived components in the consumable set. Because it is fabricated from silicon, the same material as the wafer, it participates directly in the etch chemistry and erodes over time, which is precisely why it is treated as a scheduled-replacement part rather than a permanent fixture. Its dimensional condition has a direct, measurable influence on edge etch rate, sidewall profile and critical-dimension uniformity across the outermost 10–20 mm of the wafer.
As device geometries have shrunk and edge-die yield has become economically critical on 300 mm wafers, the focus ring has moved from being a simple shielding component to a carefully engineered process-control element. Maintaining a fresh, dimensionally correct ring such as the 0200-35623 is therefore a routine part of keeping a plasma etch tool inside its process window.
The focus ring performs several interlocking functions, combining plasma shaping, electrical continuity and physical protection in a single annular part that frames the wafer on the lower electrode.
Because the focus ring is consumed by the same chemistry it helps to control, its material grade and surface condition determine both how long it lasts and how cleanly it erodes. High-purity silicon is selected specifically so that its erosion products are chemically compatible with the wafer process rather than a source of contamination.
The 0200-35623 is manufactured from high-purity silicon to keep metallic and particulate contamination to an absolute minimum during plasma exposure.
In service the ring is continuously bombarded by energetic ions and exposed to reactive fluorine- or chlorine-based species, which gradually thin and recess its upper surface.
Few consumables have as direct a relationship to edge-die yield as the focus ring. As it erodes, the step height and the local field geometry change, and the etch result at the wafer edge drifts away from the centre, often the first warning sign that a ring is due for replacement.
As a sacrificial silicon part, the focus ring fails predictably through erosion but can also fail abruptly through mechanical or thermal damage. Recognising the dominant modes helps engineers set the right replacement interval.
The primary wear mode is gradual thinning of the upper surface under ion bombardment. As the ring recesses, the step height relative to the wafer increases, the sheath geometry shifts and edge etch results drift until the ring reaches its end-of-life thickness.
Silicon is brittle, so thermal cycling, mishandling during a chamber wet-clean, or a slightly out-of-position seating can initiate cracks or edge chips. These not only alter the field locally but also shed particles that contaminate wafers and the chamber.
Polymer or by-product films can accumulate on the ring surface, and trapped particles or residue beneath the ring can break electrical contact or tilt the seating. Both conditions disturb the edge field and degrade particle performance well before the silicon itself is fully consumed.
Focus-ring replacement is a routine preventive-maintenance task, but because the part is brittle and its seating is critical to edge performance, it should be carried out carefully and in line with Toshiba’s published maintenance procedure for the specific chamber.
Because the focus ring is consumed on a predictable cycle, it is a natural candidate for planned stocking. ESCT Fab Support helps fabs keep these high-turnover edge consumables on the shelf so a worn ring never becomes the reason a chamber sits idle.
It surrounds the wafer on the lower electrode and extends the silicon surface beyond the wafer edge, shaping the plasma sheath so that edge dies are etched under conditions similar to the wafer centre. It is sacrificial, eroding over time while protecting the chuck and maintaining edge etch uniformity.
No. This is a second-source, new part supplied as an OEM-compatible equivalent to Toshiba P/N 0200-35623. It is not an original OEM-branded component, but it is manufactured and verified to match the original in form, fit and function.
Replacement intervals depend on your process chemistry, power and wafer throughput, so they are best defined in RF hours or wafer count specific to your recipe. The ring is a scheduled consumable; once edge critical-dimension uniformity or profile control begins to drift, the ring has usually reached its usable limit.
Silicon matches the wafer material, so it presents the same surface chemistry and electrical behaviour to the plasma at the wafer edge, and its erosion products are compatible with the process. Some chambers use ceramic or quartz rings in adjacent positions, but a silicon focus ring is chosen where edge process matching and low contamination are the priority.
An over-eroded ring shifts the edge field and degrades edge-die yield, while a cracked or chipped ring becomes a particle source that can contaminate wafers and the chamber. Running past the recommended end-of-life therefore risks both yield loss and additional cleaning downtime.
The standard lead time is 4–5 weeks. Because the focus ring is a regularly replaced consumable, we recommend holding buffer stock or setting up a consignment arrangement so that scheduled maintenance is never delayed waiting on a ring.
The Silicon Focus Ring (Toshiba OEM P/N 0200-35623) is a high-purity, sacrificial edge consumable that frames the 300 mm wafer in a plasma etch chamber, shaping the plasma sheath and protecting the chuck while maintaining edge etch uniformity and profile control. Because it erodes predictably and has a direct influence on edge-die yield, it is a planned-replacement part best kept in buffer stock. ESCT Fab Support offers this ring as a second-source, new, OEM-compatible part with a 4–5 week lead time, helping fabs keep their Toshiba etch chambers inside their process window without single-source supply risk.
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 Toshiba part number 0200-35623. It is not an original OEM part and is not sold as one. It is not manufactured by, endorsed by, or affiliated with Toshiba, and all manufacturer names and part numbers are quoted for identification and compatibility purposes only.
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