Carbon nitride films of uniform thickness by inverse PLD

In the present contribution we report on a target–substrate arrangement to considerably improve the homogeneity of films produced in the static-substrate inverse pulsed laser deposition (IPLD) configuration. Carbon nitride films were grown in a modified IPLD geometry, by holding a silicon substrate in the target plane and jointly rotating it with the target at 5.5 rpm. The graphite target was ablated by KrF excimer laser pulses in nitrogen atmosphere of 5 Pa pressure. The laser fluence was kept at a constant value (∼7 J/cm2) in each experiment. Typically a 1 cm × 1 cm large silicon substrate was fixed to the target within the ablated track of approx. 10 mm radius. The thickness distribution of the films was measured by profilometry on masked steps. The maximum relative deviation of the film thickness was ±6% and typically around ±2.5%. The homogeneity of the refractive index and the extinction coefficient was found to be ±0.55% and ±3.58%, respectively. An additional benefit of this co-rotating IPLD geometry is its appealing simplicity, i.e. that the target and substrate are rotated by the same motor.