THICKNESS MEASUREMENTS OF THIN FILMS WITH INTERFEROMETER BASED ON NOMARSKI METHOD

Abstract : The report describes an optical microscope with an interference attachment based on the design proposed by Nomarski, which was used by the authors for the measurement of vacuum deposited thin films. The range of thickness covered was 500 to 20,000 Angstrom units. The interferometer makes use of a doubled image produced in an arrangement whereby polarized light is passed and returned through a birefringent prism and then an analyzer to form interference fringes. This system was chosen because it requires no physical contact between the specimen and any optical component. In order to utilize the instrument to its fullest capability as a quantitative tool, properly designed steps in the films to be measured are necessary. The preparation of the samples, the measuring procedure, and the accuracy obtained with the described method are discussed and evaluated. In the Appendix a translation of the original French article by Nomarski on his design is included. (Author)