Tantalum for Semiconductors

Over the years, H.C. Starck has continued its efforts to improve the crystallographic homogeneity within a sputter target by inventing a process that essentially eliminates texture gradients in wrought and mill products (100% dense, low interstitial). H.C. Starck’s expert technology engineers work with customers to design processes that will produce plates with desired texture and grain size beyond the standard offerings.

Tantalum has high melting points, much higher than semiconductor process applications or device operating temperatures, making the properties desired electrical conductivity, strength, corrosion resistance, and stiffness – all stable over normal operating temperature ranges.


semiconductor target


Tantalum as a Diffusion Barrier
Copper and tantalum are almost insoluble in each other where tantalum readily sticks to silicon and silicon dioxide. To create good adhesion, tantalum and tantalum nitride are deposited prior to the copper seed layer creating good electrical contact and eliminating contamination of the copper conduction line during subsequent heat treatment. Tantalum’s high natural strength with its low thermal expansion coefficient and its ability to stick to both copper and silicon make it the perfect choice for a diffusion barrier to prevent copper and silicon from interacting.


Electron Beam (EB) Melting Forms Tantalum Ingots

H.C. Starck’s thermo-mechanical processing to convert electron beam (EB) melted ingots into sputter target blanks or pre-forms with consistent microstructure and crystallographic orientation is very important to the sputter deposition process. We control the whole process from EB melting through production of sputtering target materials in-house ensuring repeatability and performance. H.C. Starck facilities are capable of making all sputter target shapes and sizes for the different OEM designs including the anticipated sizes for 450mm assemblies.

Tantalum for Integrated Circuits

Tantalum’s unique properties and high quality performance make it the best choice material for integrated circuits:

  • Diffusion Barrier to prevent interaction of copper seed layer and silicon
  • On chip resistor (oxynitrides) – very stable resistivity with temperature
  • On chip capacitor – very stable capacitance with temperature due to tantalum oxide’s high dielectric constant

High Purity Tantalum

H.C. Starck’s tantalum produces consistently high quality tantalum products with controlled purities meeting exacting “ship-to-control” requirements: 

  • H.C. Starck supplies up to 4N5 purity discs in thicknesses up to 1” (inch) for 300mm Tantalum
  • We offer pre-forms for all variants in design for 300mm tantalum hollow cathode
  • Flat panel display (FPD) targets are produced with up to 4N5 tantalum seamless plates without joints
  • Higher purity ingots are provided, though purity beyond 5N can dramatically impact processing costs.


Elements

3N5 Purity
99.95% Ta

4N Purity
99.99% Ta

4N5 Purity
99.995% Ta


Max. ppm

Max. ppm

Max. ppm

Al

5

1

0.5

Ca

5

1

0.5

Cl

3

1

1

Co

1

0.5

0.5

Cr

5

1

0.5

Cu

5

1

0.5

Fe

5

1

0.5

K

1

0.4

0.1

Li

1

0.5

0.05

Mg

5

1

0.5

Mn

5

1

0.5

Mo

40

10

10

Na

1

0.4

0.4

Nb

300

100

50

Ni

5

1

0.5

Pb

1

1

1

Si

5

1

0.5

Sn

5

1

0.5

Ti

5

1

0.5

V

5

1

0.5

W

150

80

50

Zn

5

1

0.5

Zr

5

1

0.5

Max Total
Detectable Metallics

500

100

50


INTERSTITIALS

C

40

30

20

O

80

80

80

H

10

5

5

N

40

30

20

S

1

1

1


Nominal Thickness**
Thickness Tolerance
Length, Width, and Diameter Tolerances
Flatness Tolerances*

Round to Round
"R2R"
Square to Round
"S2R"
Sheared Edge
(Rectangular Plates Only)
Water Jet Edge
Machined Edge
Level Rolled

0.1250”
- 0.2999”
+ .050” / -0
+ .020” / -0
+0.1875“
/ -0
+0.030”
/-0
+0.020"
/-0
0.015"
per foot
0.3000”
- 0.4739”
+ .050” / -0
+ .025” / -0
+0.25"
/-0
+0.040”
/-0
+0.030"
/-0
0.020"
per foot
0.4740”
- 0.650”
+ .050” / -0
+ .030” / -0
NA
+0.060”
/-0
+0.030"
/-0
0.025"
per foot








H.C. Starck is certified in ISO9001 and ISO14001 quality and environmental systems.

Tantalum Plate and Disc

H.C. Starck offers tantalum (Ta) plate and near-net shapes for the manufacture of physical vapor deposition (PVD) sputtering targets.

  • Sizes Available:
    • Diameter: 3" to 18"
    •  Thickness: .2" to 1.5" and greater
    • Typical rectangles: 6" to 30" or larger
  • Target blank sizes range from small research cathodes to large 100 pound planar targets
  • Exacting standards of purity and dimensional tolerances
  • Density: 0.6 lb/in3 or 16.6 g/cm3

  • Tolerances
    •  Thickness: Rolled and leveled plates have a normal thickness tolerance of ±5% which can
 be tightened to ±.010" depending on dimensions required
    •  Flatness: .005"-.010" TIR depending on size and thickness

    • Grain Size: ASTM 4 or finer for targets made from plate under .4" thick 


Conflict-Free Material with Unique Characteristics

H.C. Starck’s tantalum supply chain has been declared, consecutively for the last several years, conflict-free by a third-party auditor assigned by the Electronics Industry Citizenship Coalition (EICC) and Global e-Sustainability Initiative (GeSI) as part of the Conflict-Free Smelter (CFS) Validation Program.

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