Tungsten Sputtening Targets for Semiconductor Applications

To develop and produce high quality sputtering targets, Blesswmo carefully evaluates which manufacturing method to use for each material to meet the following product quality goals.

· Sputtering targets made using optimum manufacturing methods!

Bleswmo has developed 2 types of tungsten targets for different manufacturing methods depending on the particular application required by the semiconductor process. One type was developed for products at a purity grade of 5N is an inexpensive and employs the powder sintering method. High-purity CVD tungsten target boasting a purity grade of 7N and using CVD (chemical vapor deposition) on sections requiring higher quality.

· Low-particle targets
Blesswmo has developed sputtering targets that suppress generation of particles that can be the source of problems in the sputtering process.
Gaseous elements are one factor in causing particle emissions especially in aluminum targets and we are working to lower emissions by utilizing a vacuum melting method in the refining and ingot purification processes.

· Attaining high uniformity by adjusting the metal microstructure
Blesswmo uses manufacturing processes that ensure high uniformity and a fine metal microstructure in most of its targets for semiconductor products including high purity cobalt targets and titanium targets.
Utilizing a fine metal microstructure having a high degree of uniformity for example allows uniform the magnetic flux leakage on the target surface of high purity cobalt targets.

· Meticulous quality control system
Integrated process manufacturing at Blesswmo takes product characteristics and contours into account during production. Sophisticated analysis/evaluation system such as the GD-MS (glow discharge mass spectrometer) ensure purity along with a high level of quality.

Tungsten-titanium sputtering targets

The high atomic weight of tungsten, the high level of corrosion resistance of titanium, its good adhesion to many different surfaces, coupled with the solubility of these materials all go to make tungsten-titanium (WTi) the ideal solution for dense layers to prevent foreign atom diffusion.

That is why WTi with 10 % Ti by weight is used as a diffusion barrier and adhesion layer during the metallization process in microchips fabrication. In this field of application, WTi separates the semiconductor and metallization layers, e.g. aluminium and silicon or copper and silicon.

In flexible thin-film solar cells (CIGS), a WTi barrier layer prevents iron atoms in steel substrate from diffusing through the molybdenum back contact and into the CIGS semiconductor.

Why is that important? Without diffusion barriers, copper and silicon would form an intermetallic phase which would significantly degrade the function of the semiconductor in microchips. And it only takes a few parts per million of iron in the semiconductor to significantly reduce the efficiency of CIGS solar cells.