Bo-Huei LIAO, Cheng-Chung LEE^*, Cheng-Chung JAING¹, and Ming-Chung LIU

Thin Film Technology Center/Department of Optics and Photonics, National Central University, Chungli, Taiwan 320
¹Department of Electronic Engineering, Optoelectronics Technology Research Center, Minghsin University of Science and Technology, Hsinchu 304, Taiwan

(Received July 14, 2008; Accepted April 14, 2009)

In this study, AlF₃ thin films were deposited by pulse magnetron sputtering of Al targets with different ratios of CF₄/O₂ gas and at different sputtering powers. The optical and mechanical properties of the AlF₃ thin films were analyzed. The transmittance spectra showed no obvious negative inhomogeneous refractive indices. Denser films with a low optical absorption were obtained when high sputtering powers were used (larger than 30 W). The lowest extinction coefficient (7.3× 10^-4 at 193 nm) of the films can be reached with 12 sccm O₂ flow rate and at 160 W sputtering power. All of the residual stresses were compressive and their trends were consistent with the refractive indices. The lowest compressive stress (0.068 GPa) was obtained when the AlF₃ films were prepared at 160 W sputtering power.

Key words: aluminium fluoride, pulse magnetron sputtering, optical property, transmittance spectrum, sputtering power

^*E-mail address: cclee@dop.ncu.edu.tw