Hiroyasu Kojima

Large scale and low resistance ITO films formed at high deposition rates

Preparation of low resistance indium tin oxide (ITO) films on large scale glass substrates has been studied for architectural applications. Coating was carried out by an inline-type plasma-enhanced deposition system with multiple low voltage electron beam (EB) sources based on arc discharge. When Ar was used as the arc discharge gas, low resistance (1 ≈ 2 Ω sq−1) ITO films were obtained on a large scale (1.8 m × 3.2 m) float glass substrate at high deposition rate (6000 A min−1) and low substrate temperature (<200°C). The minimum specific resistivity of the film was 1.7 × 10−4 Ω cm. In order to increase the deposition rate further, He was used as the arc discharge gas instead of Ar. An extremely high deposition rate of 12 500 A min−1 with sufficient visible transmission and low resistivity was achieved and a minimum sheet resistance of 0.9 Ω sq−1 was obtained. An architectural monolithic electromagnetic interference (EMI) shielding window was realized with the above technology. The glass with a sheet resistance of 5 Ω sq−1 showed an EMI shielding performance of -30 dB at 1 GHz.