Plasma sputtering is a technique used to create thin films of various substances. During the plasma sputtering process, a target material, in the form of a gas, is released into a vacuum chamber and exposed to a high intensity magnetic field. This field ionizes the atoms by giving them a negative electric charge. Once particles are ionized, they land on a substrate material and line up, forming a film thin enough that it measures between a few and a few hundred particles thick. These thin films are used in a number of different industries, including optics, electronics and solar energy technology.
During the plasma sputtering process, a sheet of substrate is placed in a vacuum chamber. This substrate may be composed of any of a number of different materials, including metal, acrylic, glass or plastic. The type of substrate is chosen based on the intended use of the thin film.
Plasma sputtering must be done in a vacuum chamber. The presence of air during the plasma sputtering process would make it impossible to deposit a film of only one type of particle onto a substrate, as air contains many different types of particles, including nitrogen, oxygen and carbon. After the substrate is placed in the chamber, the air is suctioned out continually. Once the air in the chamber is gone, the target material is released into the chamber in the form of a gas.
Only particles that are stable in a gaseous form can be turned into thin film through the use of plasma sputtering. Thin films composed of a single metallic element, such as aluminum, silver, chromium, gold, platinum or an alloy of these are commonly created using this process. Though there are many other types of thin films, the plasma sputtering process is best suited to these types of particles. Once the particles enter the vacuum chamber, they must be ionized before they will settle on a substrate material.
Powerful magnets are used to ionize the target material, turning it into plasma. As particles of the target material approach the magnetic field, they pick up additional electrons, which give them a negative charge. The target material, in the form of plasma, then falls to the substrate. By moving the sheet of substrate around, the machine can catch the plasma particles and make them line up. Thin films can take up to a few days to form, depending on the desired thickness of the film and the type of target material.