Specific Process Knowledge/Thin film deposition/Deposition of Tantalum

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Tantalum (Ta)

Tantalum (Ta) is a refractory metal prized for its extreme melting point, corrosion resistance, and biocompatibility, serving an array of semiconductor, optical, and engineering roles. Thin films are produced mainly by magnetron sputtering or e‑beam evaporation; process conditions determine whether low‑resistivity α‑Ta (stable body‑centered‑cubic) or high‑resistivity β‑Ta (metastable tetragonal) is obtained. In semiconductor fabrication, Ta acts as an adhesion liner and Cu diffusion barrier in interconnects, a robust gate or contact metal, and a hard mask, with α‑Ta preferred when minimal resistive loss is essential. Crucially, α‑Ta becomes superconducting below ≈4.5 K, making it valuable for superconducting nanowire detectors, qubit circuitry, and low‑loss microwave resonators. In contrast, the intrinsically stressed β-Ta phase is leveraged for thin-film precision resistors, microheaters, and radiation-hard sensors. Both phases benefit from Ta’s chemical inertness and x‑ray opacity, supporting x‑ray/EUV optics, MEMS springs, biomedical implants, and durable corrosion‑resistant coatings, underscoring Ta’s versatility when a stable, tunable metallic film is required.

Tantalum deposition

Tantalum can be deposited by e-beam evaporation and sputter deposition. In the chart below you can compare the different deposition equipment.

Sputtering of Tantalum in Sputter-System Metal-Nitride(PC3)

• Sputtering of Ta in Sputter-System Metal-Nitride(PC3). (Recommended approach)

Sputtering of Tantalum in Sputter-System (Lesker)

• Sputtering of Ta in Sputter-System (Lesker).

E-beam evaporation of Tantalum

Tantalum can be deposited by e-beam evaporation in our two Temescal tools.

• E-beam evaporation of Ta in Temescal

	E-beam evaporation (Temescal and E-beam evaporator (10-pockets))	Sputter (Lesker)	Sputter deposition (Sputter-system Metal-Oxide (PC1) and Sputter-system Metal-Nitride (PC3))
General description	E-beam deposition of Ta (line-of-sight deposition)	Sputter deposition of Ta (not line-of-sight)	Sputter deposition of Ta (not line-of-sight)
Pre-clean	Ar ion source (E-beam evaporator Temescal only)	none	RF Ar clean
Layer thickness	10Å to 0.2 µm*	10Å to 6000Å	10Å to 6000Å
Deposition rate	0.5Å/s to 1Å/s	~0.3Å/s	at least in the range 1 Å/s to 4 Å/s
Batch size	Up to 4x6" wafers Up to 3x8" wafers (ask for holder) Many smaller pieces	Pieces or 1x4" wafer or 1x6" wafer	Pieces or 10x4" wafer or 10x6" wafer
Allowed materials	Silicon Silicon oxide Silicon (oxy)nitride Photoresist PMMA Mylar Metals See also the cross-contamination sheet	Silicon Silicon oxide Silicon nitride Silicon (oxy)nitride Photoresist PMMA Mylar SU-8 Metals Carbon	Silicon Silicon oxide Silicon nitride Silicon (oxy)nitride Photoresist PMMA Mylar SU-8 Metals Carbon
Comment	Tantalum deposition heats the chamber* Heating to 250 °C available in the 10-pocket e-beam evaporator.	2-inch Ta target.	3-inch Ta target. Heating available to 600 °C.

* The max thickness is limited to 200 nm as Ta deposition heats the chamber. If you wish to deposit more than that, it has to be done in several steps. The temperature on the back of a Si wafer rose to above 160 °C during deposition of 40 nm Ta even when using a cooling plate. If you wish to e-beam deposit Ta, please contact the Thin film group.