Study on the ion-beam etching process to remove the oxide layer in the cold-rolled steel production process

Abstract

Cold-rolled steel (CRS) has been used worldwide in several industrial fields such as automobiles, electric/electronic appliances, etc. Recently, steel companies requested a higher performance coating layer, such as Zn-Mg or Al-Mg, due to its corrosion resistance. If a coating process is to be applied removal of the oxide layer from the CRS surface is necessary to improve adhesion, which is the main problem with using a coating. If the oxide layer is to be removed in a mass production process, the etching rate needs to be over 10 nm/sec (as a Si standard) because the production-line speed is 100–200 m/min. Therefore, our research developed a high-current, large-area ion-beam source to apply a high-rate etching process to the CRS before the coating process. To develop the high-rate etching source, we considered the high-density plasma generation, a high-current, large-area extraction system, and the lifetime of the ion source. The current density of the ion beam and the ion beam’s distribution over a wide range were measured by using a single-directional, electric-type Faraday cup. The high-rate ion-beam etching process depends on the ion beam’s current density and the distance from the target to the source (T.S.). We carried out a high-rate etching process of over 10 nm/sec at a T.S. distance of 300 mm.