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The Graphite Beam Stop (OEM P/N 0020-83786) is a high-purity machined graphite component used in the low-current (LC) beamline section of Applied Materials ion implanters. Its job is deceptively simple but absolutely critical: it intercepts, terminates and absorbs unwanted portions of the extracted ion beam, stray species, off-axis trajectories and the beam itself during tuning, masking and certain non-implant states, while shielding adjacent surfaces from the energy, sputtered material and secondary particles that result from that interception. In a tool that routinely accelerates dopant ions to tens or hundreds of keV, a beam carrying real power must have somewhere safe to go, and the beam stop is where it goes.
Positioned within the beamline downstream of extraction and mass analysis, this component sits in the high-vacuum, high-energy environment characteristic of source and beamline hardware. The “shielding” designation in its name reflects that it is not merely a passive target but is shaped and oriented to confine sputtered graphite, suppress backscatter and protect surrounding insulators, apertures and metallic structures from beam strike and contamination. The low-current (LC) qualifier indicates it is matched to the lower-current operating regimes of the implanter, where beam geometry, dose precision and clean termination of the beam are paramount.
Because it is a sacrificial, beam-facing graphite element, this beam stop is a maintenance consumable. It erodes predictably under continuous ion bombardment and is replaced on a planned basis to preserve beam integrity, vacuum cleanliness and dose accuracy. Sourcing a dimensionally faithful, high-purity equivalent therefore keeps an implanter inside its process window between scheduled preventive maintenance cycles.
Within the implanter beamline, the graphite beam stop performs several interlocking functions that together protect the tool and safeguard the implant process. Its low atomic number, high thermal tolerance and low sputter yield make graphite the material of choice for absorbing energetic ions without becoming a source of harmful metallic contamination.
The beam stop is machined from high-purity, fine-grain graphite specifically because of how the material responds to energetic ion bombardment. Graphite tolerates extreme localised heating without melting, radiates and conducts heat away from the impact zone, and sputters at a comparatively low rate. Equally important, any material that is sputtered is carbon rather than metal, so it does not introduce yield-killing heavy-metal species into the beamline or onto the wafer. Purity matters: trace metallic impurities in low-grade graphite can be liberated under the beam and redeposited as contamination, which is why a faithful high-purity equivalent is needed.
Beyond the raw material, the beam stop’s machined geometry is what delivers the shielding function. Faces and pockets are shaped to capture the beam at an angle that traps sputtered material and limits backscatter toward sensitive surfaces. Mounting features, edges and clearances must reproduce the OEM profile precisely so the part seats correctly relative to the beam path and the surrounding hardware. A part that is dimensionally faithful preserves the intended beam-to-stop alignment; one that is not can allow beam clipping, hot spots or stray current paths that degrade tuning and shorten component life.
A correctly functioning beam stop is invisible when it works and immediately disruptive when it does not. Its condition feeds directly into beam stability, contamination control and the implanter’s ability to hold dose and uniformity within specification.
The primary wear mechanism is gradual sputter erosion of the beam-facing surface. Continuous ion impact removes graphite over time, deepening the impact pocket and eventually altering the shielding geometry. Once erosion is advanced, the stop can no longer trap sputtered material effectively, and the changing surface can perturb beam termination and local fields.
Repeated heating and cooling cycles as the beam loads and unloads the part can drive thermal-mechanical stress, particularly at edges and around mounting features. Over many cycles this can lead to micro-cracking, edge degradation or flaking, which both shortens the part’s usable life and generates particulate that contaminates the beamline.
Sputtered graphite and trapped process residues build up on and around the stop over service life, and flakes of redeposited material can dislodge as particles. A worn, contaminated or improperly seated stop can also drift out of correct alignment with the beam, allowing clipping, hot spots or stray current that destabilise tuning and accelerate wear of neighbouring hardware.
Replacement should be carried out by qualified service personnel during scheduled preventive maintenance, observing the implanter manufacturer’s procedures, lock-out and high-voltage safety practices, and cleanroom and vacuum-handling discipline. The following sequence outlines a typical approach.
Because the graphite beam stop is a planned consumable, fabs benefit from holding a reliable supply of dimensionally faithful, high-purity replacements rather than relying on extended OEM lead times. ESCT Fab Support specialises in source and beamline hardware for AMAT implanters, supplying parts manufactured and verified to match the original in form, fit and function.
It intercepts and absorbs unwanted or off-axis ion beam current in the low-current beamline section of an AMAT implanter, converting beam energy into heat in the graphite mass while shielding surrounding components from beam strike, sputtered material and backscatter. It gives the beam a safe, defined place to land during tuning, masking and non-implant states.
No. This is supplied as a new, OEM-compatible replacement part. It is manufactured and verified to match the original AMAT component (OEM P/N 0020-83786) in form, fit and function, but it is not an original OEM part and is not sold as one. The AMAT part number is provided for cross-reference and identification only.
Graphite withstands extreme localised heating without melting, has a low sputter yield, and, crucially, sputters carbon rather than heavy metals. This minimises the risk of metallic contamination reaching the wafer, which is why low-Z, high-purity graphite is the standard choice for beam-facing termination surfaces in ion implanters.
It is a consumable that erodes gradually under ion bombardment, so replacement intervals depend on beam current, operating time and the fab’s process recipe. Most fabs replace it on a planned preventive maintenance schedule, guided by inspection of erosion depth, contamination build-up and any signs of cracking or flaking.
Advanced erosion changes the shielding geometry, allowing sputtered material and backscatter to escape, while flaking can shed particles into the beamline. A misaligned or degraded stop can also cause beam clipping, hot spots and stray current, destabilising tuning, threatening dose accuracy and accelerating wear on neighbouring hardware.
Reference both the AMAT OEM number, 0020-83786, and the ESCT part number, ES227-0006, when ordering. If you are unsure whether this is the correct beam stop for your specific beamline configuration, ESCT’s technical team can help confirm the match against your tool before you commit to an order.
The Graphite Beam Stop (OEM P/N 0020-83786, ESCT P/N ES227-0006) is a high-purity, low-Z consumable that terminates and absorbs unwanted ion beam current in the low-current beamline of AMAT ion implanters while shielding surrounding hardware from beam strike, sputtered debris and backscatter. Its purity, thermal stability and machined shielding geometry directly underpin beam stability, contamination control and dose accuracy. As a sacrificial part with predictable erosion, it rewards a disciplined spare-parts strategy, and ESCT Fab Support supplies a dimensionally faithful, high-purity equivalent to keep implanters within their process window between maintenance cycles.
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 Applied Materials part number 0020-83786. It is not an original OEM part and is not sold as one. It is not manufactured by, endorsed by, or affiliated with Applied Materials, and all manufacturer names and part numbers are quoted for identification and compatibility purposes only.
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