Laser annealing of thin ITO films on flexible organic substrates

Indium–tin oxide (ITO) thin films on polyethylene-terephthalate film substrates are fabricated at room temperature by reactive magnetron sputtering. The minimum of the resistivity of ITO films formed at room temperature is 4.5 $\times$ 10$^{-4}$ $\Omega$ cm. The laser annealing of ITO films from 140 to 600 nm in thickness increases their conductivity from 10 to 24% depending on the energy density to the film and irradiation dose. It is established that the laser annealing of films up to 250 nm in thickness is efficient at an energy density in the range from 12 to 35 mJ/cm$^2$. Films from 390 to 600 nm in thickness should be annealed by laser radiation with an energy density of no lower than 46 mJ/cm$^2$. A model problem taking into account the influence of radiative cooling and heat exchange of the film and the substrate on the variation in the film temperature over time during laser annealing is considered. A one-dimensional thermal conductivity equation for a bilayer medium is used. The maximal stresses in the ITO film under various annealing modes are calculated.