Thickness Measurement of Thin Soft Organic Films

This paper compares chromatic white light (CWL) and interference microscope measurements aiming to find a proper non-contact method for a thickness determination of thin soft organic films. Standard samples with vacuum deposited aluminum films of different thicknesses in the range of 50-1000 nm were prepared and measured by both methods. It was found that the CWL technique is proper for a measurement of thin soft organic films with higher than 40-50 nm film thicknesses. As a complementary feature of the method 2D and 3D surface morphology imaging of the films could be recorded and the surface film roughness could be calculated. In a case of optical inhomogeneity the method requires covering with a uniform high reflective coating. The interference microscopy method results in a relatively lower film thickness with a higher standard deviation and a higher standard relative error. It could be connected with the resolution of the interferograms measured.