Because intervening gas can affect the deposition of sputtered atoms onto the substrate, especially at high pressure, coatings made with conventional DC sputtering may contain voids that make the coating irregular or even spongy. When the operating plasma is the same species as the target, however and especially when the atoms that reach the substrate are ionized voids are not formed. A high proportion of ions also helps deposition reach into the narrowest crevices of the negatively charged substrate.
Beyond the semiconductor industry Anders sees a wide range of applications for the efficient new process, some of which may sound exotic. Because a sustained, self-sputtering plasma can operate in pure vacuum, the new method could also be used for coating materials in space, or even for ion thrusters whose fuel consists of a low-cost, noncombustible metal target, making it unnecessary to carry bottled gases or liquids into space.
Another far-out application may lie in coating the accelerating cavities of the next generation of superconducting particle accelerators with niobium, a metal notoriously difficult to work with. Since every metal behaves differently in a magnetron sputter gun, sustained self-sputtering of niobium is promising but still a challenge.
For now, Andersson and Anders's demonstration of a 250-ampere current of copper ions to a substrate far higher than any ever achieved in a magnetron system stands as an achievement with the potential to revolutionize some of the semiconductor industry's most important manufacturing processes.
|Contact: Paul Preuss|
DOE/Lawrence Berkeley National Laboratory