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Microstructure changes of ZrN films deposited onto Si substrates by unbalanced magnetron sputtering were investigated over temperatures of 200–1100 °C in vacuum. The microstructure and morphology of the films were investigated by means of X-ray diffraction and field-emission scanning electron microscopy. The residual stress was determined using a laser scanning curvature measurement method. Neither color change nor oxides could be discerned over the whole investigated temperature. Scarce round micro-blisters, due to the increase of residual compressive stress in the films, were found above 400 °C. The texture coefficient, lattice parameter, and average strain of the films varied with annealing temperature. The measured residual stresses reached a minimum, i.e., − 7.0 GPa at 400 °C. Subsequently, the stress relaxed with temperature and became tensile at 1000 °C. Additionally, the Young's Modulus of the films could be obtained from the residual stress and average strain relation. The evaluated value was 380 ± 70 GPa, which is comparable to those reported from the literature; nevertheless, this technique is nondestructive and much simpler.

Silicon nitride (SiN x ) films deposited on flexible polyethersulfone (PES) substrates by plasma-enhanced chemical vapor deposition (PECVD) have been investigated for water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) barrier applications. Details of the NH 3 /SiH 4 flow ratio and chamber pressure effects on the SiN x /PES properties in terms of chemical bonding, transmittance, refractive index, deposition rate, adhesion, roughness, OTR and WVTR were investigated. When the NH 3 /SiH 4 flow ratio increased from 1.43 to 10, evident variations in refractive index and transmittance of the SiN x /PES samples were observed. Moreover, as the chamber pressure increases from 26.7 to 133.4 Pa, the deposition rate, adhesion and roughness increase while no evident variations in WVTR and OTR were observed. Under optimum conditions, the WVTR and OTR of 100-nm-thick SiN x barrier coating on PES at 150 °C decreased to a value of near 0.01 g/m 2 /day and 0.01 cm 3 /m 2 /day, respectively. This indicates that the SiN x barrier on PES has high potential for flexible display applications.

Silicon oxide (SiOx) films deposited on flexible polyethersulfone (PES) substrates by plasma-enhanced chemical vapor deposition (PEVCD) have been investigated for transparent barrier applications. Although the water vapor transmission rate (WVTR) of PES (∼28 g/m2/day; thickness: 200 μm) is higher than that of the polyethylene terephthalate (PET; ∼16 g/m2/day; thickness: 188 μm), the PES substrate can withstand process temperatures of up to 180 °C, providing more flexibility in the design of device processing. Details of the substrate-temperature and film-thickness effects on the SiOx/PES properties in terms of transmittance, refractive index, deposition rate, adhesion, roughness, and WVTR were described. When the substrate temperature increased from 80 to 170 °C, the deposition rate, adhesion, and roughness values were found to increase while the WVTR decreased to a value of near 0.3 g/m2/day at 150 °C. With increasing the oxide thickness from 50 to 500 nm, the surface roughness increased from 2.71 to 5.84 nm. A lower WVTR value can be achieved under a barrier thickness of 200 nm. Further improvement was carried out by depositing a 100-nm-thick SiOx film on both sides of the PES substrate, which resulted in a minimum WVTR of 0.1 g/m2/day. The double-sided coatings on PES could balance the stress and greatly improve the WVTR data.