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The Anti-Cathode with Modified Shaft (OEM P/N 0020-81482) is a high-purity source electrode used in the arc chamber of Applied Materials (AMAT) ion implanters of the XR80 and 9500 class. In an indirectly-heated cathode (IHC) ion source, the anti-cathode, also referred to as the repeller or reflector, sits at the end of the arc chamber directly opposite the cathode. Its job is electrostatic and thermal: it reflects primary and secondary electrons back into the discharge volume so that the arc plasma remains dense, stable and confined along the axis of the chamber.
The “modified shaft” designation distinguishes this variant by its supporting stem geometry, which carries the reflecting face into position, provides the electrical and thermal path back through the source insulator stack, and locates the electrode precisely relative to the cathode and the extraction aperture. Because the anti-cathode operates inside the most aggressive environment in the entire beamline, surrounded by an arc discharge at high temperature, bombarded by energetic ions and exposed to reactive dopant species such as fluorides, arsenic and phosphorus, both the reflecting face and the shaft are consumable and are routinely replaced during source rebuilds.
As a precision source component, the anti-cathode has a direct influence on arc stability, beam current and the overall lifetime of the ion source. A worn, eroded or misaligned anti-cathode degrades plasma confinement long before it fails outright, so it is treated as a planned-replacement item within fab preventive maintenance schedules.
Within the IHC source, the anti-cathode completes the electron-confinement geometry that allows a stable, high-density arc to be struck and maintained. It performs several interlocking functions:
An anti-cathode survives only because it is built from refractory materials selected for high melting point, low sputter yield and resistance to chemical attack by reactive dopant feedstocks. Material choice and surface condition govern both how long the part lasts and how cleanly the source runs.
Anti-cathodes for this class of source are typically machined from tungsten or molybdenum, materials that withstand the elevated temperatures of an active arc while keeping sputter erosion of the reflecting face to a minimum.
The flatness, finish and position of the reflecting face, and the rigidity of the modified shaft that holds it, determine how predictably electrons are returned to the plasma over the life of the source.
Because the anti-cathode shapes the plasma at one end of the arc chamber, its condition feeds directly into the parameters that fabs care about most, dose accuracy, uniformity and uptime. A degraded anti-cathode produces effects that are felt well beyond the source itself:
The anti-cathode is a consumable, and its decline follows recognisable patterns that experienced source engineers track from one rebuild to the next.
Continuous ion bombardment slowly removes material from the reflecting face. As the face recedes and roughens, electron reflection becomes less efficient and the arc must be driven harder to maintain current, accelerating the rest of the source toward end of life.
Repeated heating and cooling cycles stress the modified shaft. Over many source cycles this can lead to warping, creep or cracking that shifts the reflecting face out of position, disturbing the symmetry of the arc and the registration of the electrode within the source stack.
Reactive dopants, particularly fluorine-bearing species, chemically attack the electrode and drive halogen-cycle transport that grows deposits and whisker-like structures on and around the part. These deposits can create leakage paths, glitching and short circuits that destabilise the arc before any visible mechanical failure.
The anti-cathode is replaced during a scheduled ion source rebuild, alongside the cathode, filament and other arc chamber consumables. The following sequence reflects good practice; always work to the relevant AMAT service documentation and your site’s safety procedures.
Because the anti-cathode is a planned-replacement consumable, holding qualified stock is central to keeping implant tools available. ESCT Fab Support supplies this electrode as a cost-effective, form-fit-function alternative to the OEM part, helping fabs control source-rebuild costs without compromising performance.
It sits opposite the cathode at the end of the arc chamber and reflects electrons back into the discharge. This lengthens the electrons’ path, raises ionisation efficiency and keeps the arc plasma dense and stable, which in turn supports a steady extracted beam current.
No. This is not an original OEM part. It is supplied by ESCT Fab Support as a new, OEM-compatible anti-cathode that cross-references to AMAT P/N 0020-81482 and is verified to the form, fit and function of the original component. It is intended as a direct replacement for the equivalent OEM consumable.
It identifies a specific variant of the anti-cathode in which the supporting stem geometry differs from the baseline part. The shaft carries the reflecting face into position, provides the thermal and electrical path back through the source, and locates the electrode accurately. The part is built to that modified specification so it seats and performs as intended.
Lifetime varies with dopant species, arc power, gas flow and duty cycle. As a consumable exposed to sputtering and chemical attack, it is normally replaced on a planned schedule during source rebuilds rather than run to failure, so fabs hold spare stock to keep change-outs efficient.
Anti-cathodes for this source class are typically machined from refractory metals such as tungsten or molybdenum, chosen for their high melting points, low sputter yield and resistance to the reactive species present in the arc chamber. High-purity stock is used to avoid introducing contaminants into the beam.
This anti-cathode is offered with a lead time of approximately 2.5 weeks. Quote ESCT P/N ES227-0020 or AMAT P/N 0020-81482 when enquiring, and the ESCT team can confirm availability and assist with selecting compatible source-rebuild consumables.
The Anti-Cathode with Modified Shaft (AMAT P/N 0020-81482, ESCT P/N ES227-0020) is a refractory-metal reflecting electrode at the heart of the AMAT ion implanter arc chamber. By returning electrons to the discharge it sustains a dense, stable plasma that underpins beam current, dose accuracy and uniformity. As a consumable subject to sputter erosion, thermal fatigue and chemical attack, it is a planned-replacement item that rewards disciplined spares management. ESCT Fab Support supplies it as a form-fit-function alternative with a dependable lead time, helping fabs keep their implant tools running productively.
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 0020-81482. 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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