Eiichi Ando

Moisture resistance of the low-emissivity coatings with a layer structure of Al-doped ZnO/Ag/Al-doped ZnO

Abstract The moisture durability of sputtered low-emissivity (low-e) coatings with a single silver layer structure of ZnO/Ag/ZnO/glass and Al-doped ZnO/Ag/Al-doped ZnO/glass was investigated. Zinc oxide and aluminum-doped zinc oxide (AZO) films were reactively deposited from pure Zn, 99Zn1Al, 97Zn3Al, 95Zn5Al, 90Zn10Al (at.%) targets. The aluminum content in the AZO films was measured by secondary ion mass spectroscopy (SIMS). The deposition rate and internal stress of the AZO films were measured. After a moisture durability test at 50°C in 95% relative humidity for 12 days, the coatings were analyzed using optical microscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was observed that the Al addition reduced the internal stress of the oxide films, and the AZO/Ag/AZO coatings had a better moisture resistance. However, the Al addition led to a decreased deposition rate of the oxide films, and the addition of excess Al resulted in a different moisture degradation with a hazy appearance that might be due to an undesirable hydrate formation in the low-e coating.

Solar control coating on glass

Abstract One of the various solar control glasses, a silver-based multilayer film formed by sputtering is becoming increasingly important because of its excellent and versatile performance. Recently major progress has been made in the sputtering process by several manufacturers, which has enabled both a stable and high rate of deposition. Efforts to improve the durability of sputter coating have been maintained seeking a flexible production process and expanded applications.

Optical and mechanical properties of Cr and CrNx films by dc magnetron sputtering

The optical, electrical and mechanical properties of chromium and chromium nitride films were investigated. Films of around 50 nm in thickness were deposited on glass substrates by dc sputtering of a Cr target with different levels of introduced argon and nitrogen flows. The real part of the refractive index of the film at 632.8 nm decreased from 3.6 at 0% N2 to 2.9 at 100% N2, while the imaginary part increased from 4.1 at 0% N2 to 4.4 at 20% N2 and then monotonically decreased to 2.3 at 100% N2. The electrical resistivity of the film increased at around 60% N2 and achieved a maximum of about 1 × 10−2 Ω cm at 80% N2, where the film had a Cr:N atomic ratio of 1.4:1.0 according to Auger electron spectroscopy (AES). In a Taber abrasion test, the area of the film peeled from the substrate was largest for the CrNx film at 60% N2, whereas in a sand eraser abrasion test, the area was largest for the Cr film. The inconsistent results between the two abrasion tests are discussed from a viewpoint of the effects of friction, adhesion strength and internal stress.

Materialistic Difference in Macroscopic Friction Coefficients of Sputtered Metal Oxide Thin Films Deposited on Glass

The origin of the difference in macroscopic friction coefficients of various metal oxide thin films sputtered on glass substrates was investigated from viewpoints of surface roughness and adhesion. Surface roughness and adhesive force were evaluated by atomic force microscopy (AFM). Thin films of the ZrO2–SiO2 system showed a minimum friction coefficient at 50 mol% SiO2–ZrO2. This could be explained by an increase in the number of smooth areas on the film surface. ZnO, Al2O3, SnO2, TiO2 and Ta2O5 thin films showed friction coefficients which varied from material to material. Oxide films with weaker metal-oxygen (M-O) bond were found to become highly frictive. This could be understood by the difference in the number of bonds formed between the film surface and the opponent material.

A comparative study of an unbalanced magnetron with dielectric substrate with a conventional magnetron through the use of hybrid modelling

The influence of the differing magnetic field arrangements in both an unbalanced magnetron (UBM) and balanced magnetron (BM), both of which employ a dielectric substrate, on plasma characteristics has been numerically investigated under identical pressures and voltages. The UBM exhibits some interesting intrinsic characteristics with regard to the bulk plasma and the incident flux on the dielectric substrate. A property unique to the UBM is the appearance of negative plasma potential owing to the slightly excess amount of electrons when a magnetic field is arranged parallel to the axis of the bulk plasma in a cylindrical reactor and an electric field is arranged transversely to this axis. The dielectric substrate is negatively deep-biased, as compared with that in the BM, and is exposed to positive ion impact with a higher energy and flux, which will be controlled by changing the magnitude and direction of the external magnetic field.

Zirconium silicon oxide films for durable solar control coatings

Abstract Zirconium silicon oxide films were deposited by dc reactive magnetron sputtering of ZrSi alloy targets. The character and durability of these films were investigated. Thin film X-ray diffraction analysis showed that the film structure changed from crystalline to amorphous with an abrupt decrease of internal stress for an SiO 2 content of more than 20 mol%. Reduction of friction due to the amorphous structure was related to an improved mechanical durability. Films with an SiO 2 content of 30–90 mol% were favorable as a durable protection layer. Taber abrasion of a double-layer system (amorphous ZrSi oxide/TiN x /glass) indicated that not only the reduction of friction but also the oxide thickness was a key factor for the improved mechanical resistance.

Measurement of the adhesion strength of metal oxide and metal nitride thin films sputtered onto glass by the direct pull-off method

We have measured the adhesion strengths of metal oxide and metal nitride thin films reactively sputtered onto glass substrates using a specially devised direct pull-off test. For double-layer coatings such as metal nitride (CrNx, TiNx)/metal oxide (Al2O3, SnO2, Ta2O5, TiO2, ZnO, ZrO2)/glass, separation usually took place at the nitride/oxide interface. The adhesion strength at the interface was found to depend on the strength of chemical bonding in the films concerned: for the same nitride top layer, the adhesion strength increased as the strength of the metal-oxygen (M-O) bond in the oxide underlayer decreased. X-ray photoelectron spectroscopy (XPS) measurements showed that a mixed layer was created at the nitride/oxide interface and that the adhesion strength at the interface increased with increasing thickness of the mixed layer. For single-layer coatings such as metal nitride (CrNx, TaNx, TiNx, ZrNx)/glass, the adhesion strength of the film to the glass substrate was found to increase with increasing ...

Sputtered tin silicon oxide films for durable solar control coatings

The optical, mechanical, and chemical properties of solar control coatings with a transparent tin silicon oxide (TSO) film were investigated. The TSO films were formed by reactive dc sputtering from alloy targets with the compositions of 90Sn-10Si, 80Sn-20Si, and 50Sn-50Si (at.%). Hereafter, the 50TSO film denotes the oxide film prepared from the 50Sn-50Si target. Triple layer (50TSO/TiN x /50TSO/glass) and double layer (50TSO/TiN x /glass) systems were studied as the solar control coating. These coatings were compared to those with the SnO 2 /TiN x /SnO 2 /glass and TiN x /glass systems. The coatings were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Auger electron spectroscopy (AES). The refractive index at 632.8 nm was measured. The 50TSO triple layer system was superior to the SnO 2 triple layer system in a sand eraser abrasion resistance and chemical durability. A thin 50TSO cover layer over a TiN x layer was effective for improving a powder abrasion resistance. Stable long term deposition of the 50TSO film was realized using a pulsed sputtering technique. The mechanical resistance improvement in the 50TSO triple layer system was discussed.