A sputtering target is the solid slab of material that physically erodes during sputter deposition, while a sputtering cathode is the full electrode assembly (target, backing plate, magnet pack, dark-space shield, cooling body) wired to the negative terminal of the power supply [S1][S3][S5].
In magnetron and RF systems, the target is bolted, indium-bonded or elastomer-bonded to a backing plate and forms the exposed face of the cathode; the two terms are used interchangeably in datasheets when a planar disc or rectangle is both [S1][S5][S6].
Defining each term at the component level
A sputtering target is a solid source of pure metal, alloy or compound (oxides, nitrides, silicides) sized from a few cm² for R&D to rectangular plates over 1 m long for flat-panel lines, with purity, density, grain size and outgassing rate called out per ASTM F-1 committee guidance [S1][S4]. A sputtering cathode is the engineered assembly: target plus backing plate, dark-space shield (anode ring), hold-down ring, magnet array in the case of magnetron cathodes, and a water-cooled body that carries away the 1-30 W/cm² power density typical of planar magnetrons [S3][S8].
Patent literature treats the assembly explicitly as a "magnetron cathode assembly for use in a cathode sputtering apparatus," confirming that the cathode is the whole hardware stack, not just the consumable face [S8].
Why the confusion exists in datasheets
Materials suppliers such as Admat, Testbourne and VEM list items as "sputtering targets" because they sell the consumable slab; equipment suppliers such as Angstrom Engineering and the Lesker Company list "sputter cathodes" because they sell the engineered holder, magnet pack and dark-space shield [S2][S3][S4][S5]. The same physical disc therefore appears as a "target" on a price list and as the "cathode face" on a chamber drawing, which is why RSM's note that "the sputtering target is the cathode target" reflects real purchasing language rather than a definition [S6].
The risk is a part-number mismatch: a 4N-purity 2-inch Mo disc is a target SKU, but the same disc specified with backing plate, indium bond and dark-space shield becomes a cathode SKU, and the two are not interchangeable on a PO [S1][S3].
Target specification versus cathode specification
Target specifications per ASTM F-1 working drafts include dimensions and flatness, purity and impurity limits, grain size, second-phase inclusions, density, outgassing rate and residual stress, plus backing-plate material, bond method and ultrasonic bond inspection for voids [S1]. Cathode-level specifications add magnetic field profile (typically 200-500 mT at the target race track for planar magnetrons), dark-space shield geometry, water-flow rate (often 2-4 L/min per kW) and anode placement above the target [S3][S8].
In short, anything that describes what is being eroded belongs on the target datasheet; anything that describes how the disc is held, cooled and confined belongs on the cathode datasheet [S1][S3].
Configurations where the two diverge further
Facing-target sputtering uses two rectangular cathodes aimed at each other with the substrate in between, so the "target" and the "cathode" are spatially separated; Angstrom's HCS variant collapses this to a single cylindrical cathode, and the cylindrical body itself is the cathode while the sputtered face is the target [S2]. In rotatable magnetrons the target is a drawn tube (often 3-4 m long for architectural glass) that rotates past a stationary magnetron cathode, so target consumption and cathode cooling are decoupled, and the two terms cannot be used as synonyms [S2].
Reactive sputtering with a metallic target (Ta sputtered in Ar+O₂ to form Ta₂O₅) reinforces the same point: the target composition drifts as an oxide layer forms on its surface, while the cathode assembly, including any pulsed-DC or RF bias electronics, stays unchanged [S1][S5]. A practical illustration of how hardware and material roles stay separate even when words blur them together is given in this comparison of deposition method options.
Selection rules that hinge on knowing the difference
Choose a target on material properties: melting point, stoichiometry for oxides, sputter yield, and cost per square metre of usable area (Ta at 2996 °C melts, but sputters cleanly because it stays solid; refractory melting point is unrelated to whether the disc can be DC-sputtered) [S5]. Choose a cathode on geometry, balance, and process mode: DC for metals, pulsed-DC for dielectrics with moderate resistivity, RF (13.56 MHz) for fully insulating targets, and rotatable cathodes for high-utilisation web coating where target material costs dominate [S3][S4][S5].
For thin-film photovoltaics, semiconductor barrier layers (TiN, TaN) and ITO transparent conductors, the binding constraint is target purity and density, not cathode design; for flexible-optical and large-area architectural glass, the binding constraint is target utilisation (planar ≈ 25-30 %, rotatable up to ≈ 80 %), so the cathode architecture dictates the consumable budget [S2][S4]. A broader side-by-side of process signals versus hardware trade-offs, including the magnetic-flow control side of the system, is laid out in the process-control reference family of pages.
Common failure modes tied to the wrong part
If a target is under-specified, the failure shows up in the film: pinholes from inclusions, arcing from porosity, and stoichiometry drift in reactive mode where the discharge voltage dropped from 530 V (metallic mode) to 390 V (oxide mode) at a 1 mTorr Ar+O₂ total pressure in the documented YSZ case [S1]. If a cathode is under-specified, the failure shows up in the hardware: target cracking from insufficient cooling, dark-space shield burn-through from poor anode placement, and nodule formation from non-uniform magnet profiles [S3].
Specifying a "cathode" when only the consumable is required inflates lead time and price; specifying a "target" when the full assembly is required leaves the magnet pack and cooling channels out of the scope of supply, which is the most common RFQ error seen in 200 mm and 300 mm tool retrofits [S3][S4].
Track two signals before the next purchase decision: the OEM datasheet line that distinguishes "target" from "cathode" (or that calls the disc a "cathode target"), and the bond method listed (indium, elastomeric, silver-filled paste), because the bond defines whether the SKU ships as a consumable or as a ready-to-install electrode [S1][S3].
Spec-level background on the components involved: pressure transmitter.
For related coverage, see Film vs Digital Radiography: Per-Exposure Cost and Chemistry Stack.