AVS 51st International Symposium
    Thin Films Wednesday Sessions
       Session TF-WeM

Paper TF-WeM8
Multilayered SiN@sub x@/SiO@sub 2@ AR Coatings with Cylindrical Cathode by Unbalanced Compressive Magnetron Sputtering

Wednesday, November 17, 2004, 10:40 am, Room 303C

Session: Optical Thin Films
Presenter: C.-S. Wang, Kanazawa University, Japan
Authors: C.-S. Wang, Kanazawa University, Japan
K. Sasaki, Kanazawa University, Japan
S.-F. Chen, National Taipei University of Technology, Taiwan
T. Hata, Center of Optical Coating Research, Japan
Correspondent: Click to Email
Excellent adhesion and high throughput production of anti-reflection (AR) coatings were examined by high and low refraction index SiN@sub x@/SiO@sub 2@ combined system. In general, the refraction of SiN@sub x@ was strongly dependent on the composition of nitrogen and it is difficult to obtain stoichiometric SiN@sub x@ in state-of-the-art techniques. In order to satisfy the requirements, we employed a cylindrical unbalanced compressive magnetron (UCM) sputtering technique. A pair of permanent magnets was adjacent to a cylindrical rotating target to increase and compress the ionization density in the region near the substrates. And the reactive gases were introduced between the cathode and UCM so as to produce discharge uniformly. We used a plasma-sprayed Si cylindrical target (6 cm in diameter and 50 cm in length) in which a 4.5 kGauss permanent magnet was built-in. Moreover, the same magnets were also sited to the both sides of the target to form convergence plasma stream forward to a glass substrate. The distance of target to substrate was 5 cm. SiN@sub x@ and SiO@sub 2@ films were deposited by alternatively changing N@sub 2@ and O@sub 2@ gases. The deposition rates of the films were as large as 2.01nm/s and 2.23nm/s respectively. The refraction index of SiN@sub x@ films was varied from 1.63 to 1.75 at 500 nm wavelength by varying Ar/N@sub 2@ flow ratio from 1 to 0, while that of SiO@sub 2@ films was 1.45 stably. According to AR simulation using above values, 4 layers system of SiN@sub x@/SiO@sub 2@ satisfies a reflection less than 1% in wide visible range (420~680 nm). Whole process without evacuation was completed within just 4 min. Additionally, according to spectroscopic ellipsometory measurement, the extinction coefficient was small resulted that high density and less defective films were obtained. This technique is useful for large scale and high performance AR coatings.