Particle growth in a sputtering discharge

Submicron to micron size particles are produced in the gas phase of sputtering discharges. These particles can contaminate thin films grown by sputter deposition. On the other hand, particle production in a discharge can be desirable when used for manufacturing fine powders. Here, experimental results are presented demonstrating particle production in an argon discharge, using a variety of target materials. The rate of particle growth varied widely, depending on the target material. Particles grown to 300 nm–5 μm, usually have one of two different shapes. Compact particles with a nearly spherical shape were produced by sputtering graphite, titanium, tungsten, and stainless steel targets, while filamentary-shaped fractal particles formed when sputtering aluminum and copper targets. Particle growth was also observed for a target made of an insulating material.