Properties of Si_3N_4-Layers Deposited by Medium Frequency Twin Magnetron Sputtering

摘要

Magnetron sputtering is the most important deposition method for optical thin film systems on large scale substrates. The main drawbacks accompanying DC reactive sputtering can be solved using an AC powered twin magnetron arrangement, leading to a stable deposition process. This paper reports on the properties of Si_3N_4-layers deposited by TwinMag?, a twin magnetron system which is already in use for industrial coating processes. An inherent property of the TwinMag coating process is the bombardment of the growing film with a high flux of high energetic, positively charged ions, leading to a denser structure and a smoother surface of the film than in the case of DC sputtering. The influence of the sputtering pressure on the internal stress, the density, the hardness and the index of refraction of the film is shown.