Permeation barrier coatings by inductively coupled plasma CVD on polycarbonate substrates for flexible electronic applications

Abstract Silicon oxide (SiO x )/silicon nitride (SiN x ) stacks and parylene thin films were deposited on flexible polycarbonate (PC) substrates using inductively coupled plasma chemical vapor deposition (ICPCVD) and a parylene reactor for permeation barrier applications. The effects of gas flow ratios on SiN x and SiO x film properties in terms of refractive index, internal stress, and water vapor transmission rate (WVTR) were investigated. It was found that the optical property and impermeability of SiN x and SiO x barrier films could be tailored by varying the gas flow ratio. The details of Ar plasma treatment effects on PC substrates in terms of contact angle, roughness, and WVTR were studied. The WVTR value of the optimum barrier structure (parylene + 3 pairs of SiO x /SiN x ) could reduce to 4.74 × 10 −5  g/m 2 /day after bending for 1000 times under a resistivity test (25 °C and 90% relative humidity). This result indicated that permeation barrier films prepared by ICPCVD could be a promising candidate for flexible electronic applications.