A new method which uses positively charged argon ions has been developed for use in the semiconductor industry, capable of sputtering copper thin films onto semiconductor substrates and wasting virtually none of the starting materials in the process.
Current techniques in practice result in the copper target being worn unevenly, requiring it to be frequently replaced after only half of the material is used. The dynamic new method however, utilises magnets to narrow the plasma or positively charged argon ions to a horizontal layer in the middle of the vacuum chamber. The application of a voltage to the copper target attracts the ions upward, striking the target and expelling copper atoms, which are then ionised as they pass downward through the plasma to settle as a film on the chip substrate.
As the argon atoms strike the entire surface of the copper target, this new technique ensures that the target is worn evenly and consumed with almost 100% efficiency, according to the Nikkei Business Daily paper.
The process can accommodate 300mm wafers by adjusting the plasma size with the magnets and the company plans to start selling devices based on this technology, in late 2009.
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