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The part designated RING, F-8SO-SI-260-3.4A is a silicon focus ring used in Tokyo Electron (TEL) 300 mm plasma etch process chambers. The “F” prefix marks it as a focus ring, the “SI” segment confirms a high-purity silicon construction, and the trailing dimensional code describes its ring geometry and approximate cross-sectional thickness. It is a consumable component that seats concentrically around the wafer at the periphery of the electrostatic chuck, forming the outer boundary of the plasma processing zone.
In a TEL etch chamber, the focus ring sits directly in the path of energetic ions and reactive species. Its job is to extend the electrical and physical edge of the wafer outward, so that the plasma sheath bends correctly over the wafer edge rather than collapsing inward. Because it is made from the same silicon chemistry as the wafer it surrounds, it presents a chemically matched surface to the plasma and avoids introducing foreign material into the etch environment.
As a directly exposed consumable, the focus ring erodes over time and is one of the components most frequently scheduled for replacement during preventive maintenance. Its condition has an outsized influence on edge die yield, making a reliable supply of dimensionally accurate, high-purity replacements central to keeping a 300 mm etch tool inside its qualified process window.
The focus ring is fundamentally an electrostatic and plasma-shaping element. By occupying the annular gap between the wafer edge and the chamber hardware, it controls how the plasma sheath terminates at the wafer periphery and how RF current returns from the edge region. Its principal functions include the following.
Because the focus ring is consumed by the same energetic environment that etches the wafer, its material grade and dimensional accuracy directly determine how long it holds process and how cleanly it erodes. Two characteristics dominate its in-chamber performance: silicon purity and resistivity, and dimensional and surface tolerances.
The ring is manufactured from high-purity silicon with a controlled resistivity so that it presents a predictable electrical load to the RF field and does not contribute metallic or particulate contamination to the wafer. Tightly specified purity keeps trace-metal release low, while a stable resistivity keeps the edge RF return path consistent from one ring to the next.
Focus ring height, inner and outer diameters, flatness and surface finish all influence how the plasma sheath sits over the wafer edge. A ring that is even slightly out of specification will shift the local sheath geometry and degrade edge uniformity, so close tolerance control is critical to maintaining qualified results.
Few consumables affect edge yield as directly as the focus ring. Because it controls the plasma boundary precisely where the most marginal die are located, its condition translates straight into process results and the number of usable die per wafer.
As a sacrificial silicon part, the focus ring degrades through several predictable mechanisms. Recognising them helps maintenance teams set realistic replacement intervals and diagnose edge process drift.
Continuous ion bombardment slowly etches the silicon, reducing ring height and changing its profile. As the ring thins, the sheath over the wafer edge sits lower, shifting edge etch rate and critical dimension until the part falls outside its qualified window and must be replaced.
Thermal cycling and mechanical handling can crack or chip the brittle silicon, particularly at edges thinned by erosion. Fragments and fracture sites generate particles that land on the wafer and can cause defects or arcing, often forcing an unscheduled chamber-open event.
Over a ring’s life its surface roughens and may accumulate polymer or by-product deposits. This changes local plasma coupling and raises the risk of flaking, contributing to particle excursions and gradual edge-uniformity drift well before the ring reaches its dimensional limit.
Focus rings are typically changed during scheduled preventive maintenance or when edge process metrics drift. Replacement should follow the tool owner’s approved maintenance procedure and contamination-control practices. A representative sequence is as follows.
Because focus rings are high-turnover consumables, fabs benefit from a dependable second source that holds form, fit and function without the cost and lead-time pressure of single-sourcing. ESCT Fab Support supplies ES7099-156 as a TEL-compatible alternative with these advantages.
It surrounds the wafer at the edge of the electrostatic chuck and shapes the plasma sheath so the etch remains uniform out to the wafer edge. It also provides a chemically matched silicon surface and supports a controlled RF return path, protecting the chuck and edge hardware from direct plasma attack.
No. This is a new, second-source part supplied by ESCT and verified to the form, fit and function of TEL OEM P/N 1D10-350647-31. It is not an original OEM component, but it is intended as a fully compatible replacement for it.
It is manufactured from high-purity silicon with a controlled resistivity, matching the chemistry of the wafer it surrounds. This keeps trace-metal and particle contributions low and gives a predictable electrical load and erosion behaviour in the plasma.
Replacement interval depends on the etch chemistry, RF power and run hours, so it varies by process. The ring is changed when erosion has reduced its height enough to shift edge uniformity outside the qualified window, or when inspection reveals cracking, chipping or excessive surface roughening. Many fabs change it on a defined preventive-maintenance schedule.
The usual signs are drift in edge etch rate or critical dimension, rising particle counts, and visible height loss, chips or surface roughening on the ring. When edge metrics move toward their control limits, the focus ring is one of the first consumables to inspect and replace.
The typical lead time is 4-5 weeks. Because focus rings are high-turnover consumables, we recommend aligning orders with your preventive-maintenance schedule and holding appropriate safety stock to avoid unplanned downtime.
The silicon focus ring ES7099-156 (TEL OEM P/N 1D10-350647-31) is a critical edge-confinement consumable for TEL 300 mm plasma etch chambers. By shaping the plasma sheath, supporting the edge RF return path and presenting a chemically matched silicon surface, it governs edge etch uniformity, particle performance and edge die yield. As a sacrificial part it erodes predictably and must be replaced on schedule. ESCT supplies it as a new, second-source, high-purity silicon ring verified to OEM form, fit and function, with a 4-5 week lead time to support planned 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 1D10-350647-31. 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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