Niobium targets are primarily employed in the reactive sputter deposition of niobium pentoxide (Nb2O5). Niobium oxide thin films are used as antireflective coatings for applications ranging from architectural glass to lenses, wave guides and filters. The optical coatings are comprised of alternating layers of niobium pentoxide (having a refractive index of about 2.17, similar to that of tantalum pentoxide) and a low refractive index material such as quartz (RI ~1.46).
Since impurities in the sputtering target can affect the optical properties of the Nb2O5 film, Firmetal offers a special high purity, target grade niobium for this market.
Chemical Purity of Sputtering and Commercial Grades
Impurities (ppm)
Sputtering Grade Niobium
Commercial Grade Niobium
Fe
<20
<100
Ni
<25
<50
Cr
<5
<10
Cu
<5
<10
Zr
<50
<200
P
<30
<30
Si
<30
<50
Ta
<400
<3000
W
<50
<500
Mo
<50
<300
Na
<3
<10
Li
<5
<10
K
<3
<10
U
<0.1
<10
Th
<0.1
<10
Others
<10
<10
C
<40
<100
O
<150
<200
N
<100
<100
H
<15
<15
Target grade niobium is available in planar forms (discs and rectangles) to the dimensional tolerances given in the table below:
Dimensional Tolerances of Target-Grade Niobium Products
