Mid frequency sputtering — a novel tool for large area coating

Since DC magnetron sputtering was introduced for the manufacturing of optical thin film systems on large area glass substrates, coating processes have suffered from poor long-term stability and low deposition rates. After long years of intensive development work, today AC (mid frequency) powered twin magnetron arrangements are capable of overcoming these drawbacks. This paper reports on the latest results of large scale deposition of materials like SiO 2 , Si 3 N 4 , TiO 2 and SnO 2 using such TwinMag systems. SiO 2 and TiO 2 , the most prominent candidates for antireflective coatings, can be deposited at rates exceeding 5 nm/s in a stable continuous process for more than 300 h. Bombardment of the growing film by a high flux of energetic ions results in dense structures, excellent optical properties and high resistance against environmental attack.