Plasma-assisted atomic layer deposition of Al2O3 moisture permeation barriers on polymers

Thin Al2O3 films of different thicknesses (10-40 nm) were deposited by plasma-assisted atomic layer deposition on substrates of poly(2,6-ethylenenaphthalate) (PEN), and the water vapor transmission rate (WVTR) values were measured by means of the calcium test. The permeation barrier properties improved with decreasing substrate temperature and a good WVTR of 5x10(-3) g m(-2) day(-1) (WVTRPEN=0.5 g m(-2) day(-1)) was measured for a 20 nm thick Al2O3 film deposited at room temperature using short purging times. Such ultrathin, low-temperature deposited, high-quality moisture permeation barriers are an essential requirement for the implementation of polymeric substrates in flexible electronic and display applications.