Colorless, transparent, c-oriented aluminum nitride films grown at low temperature by a modified sputter gun

Abstract

Colorless, transparent, pure c‐oriented AlN films have been deposited on glass substrates, with and without Cr‐Au films, utilizing a modified sputter gun. The design of the gun and of the sputtering system helps to keep the growing surface free from charged particle bombardment and excessive heat by radiation. Attention will be focused mainly on the effect of total sputtering pressure on the quality of the AlN films. A very strong magnetic field makes it possible to sputter at pressures as low as 0.133 Pa (1 μTorr). This high vacuum sputtering improves c‐orientation, surface smoothness, film color, transparency, deposition rate, and thermal expansion coefficient matching. The deposition rate of the sputter gun is as high as 2.4 μm/h at input power of 300 W.