DC Magnetron Deposition with Pure Boron Target in Reactive Gases Atmospheres

The boron-contained films was produced using the DC magnetron sputtering of a pure boron target in the atmosphere of reactive gases, such are oxygen, nitrogen, and acetylene. The use of a pure boron target in a conventional magnetron sputter is difficult, because under normal conditions boron target has a high electrical resistance. The use of a boron target, thermally insulated from the water cooled magnetic system, made it possible to gradually heat it directly in the discharge of DC magnetron to a temperature of 450–750°C and maintain stable operation of the discharge in an inert argon atmosphere. However, the use of chemically active gases in the magnetron leads to the formation of oxides, nitrides and carbides of boron not only on the deposited substrate, but also on the surface of the boron target, which in turn leads to the transition of the glow magnetron discharge of direct current into a cathode arc and disrupts the stable operation of the magnetron. To prevent arcing, buffer argon was supplied separately to the magnetron discharge gap and reactive gas to the film coating area. In such a magnetron sputtering system, boron coatings were obtained in reactive gas atmospheres. The coating deposition rate in reactive gases was about 10 nm/min with the substrate located at 7 cm from the target. Coatings with a thickness (1–3) μm were obtained. The higher microhardness of the coatings was of about 32 GPa with a Young modulus of up to 250 GPa for boron suboxide films. The properties of the coatings depending on the experimental conditions are discussed.