Measurement Of Multilayer Film'S Interface Roughness By White-Light Interference

In order to determine the quality of the materials with the required performances and reliability, a new method based on the principle, of white-light interference, which is a combination of spectrum analysis and optical fiber techniques, is proposed to measure the interface roughness of multilayer film. Its measurement range is from 0.2 micron to less than 20 micron. The relative thickness of the sample point and the reference mirror, which is less than the coherent length, is tested by analyzing the interference pattern of a Michelson interferometer. When the position of reference mirror is fixed, the relative thickness value of different measuring points on the film's interface is achieved by scanning the film's interface. According to the relative thickness data, the film's interface roughness is obtained. The experimental results show that the testing error of this method is within 2 rim. This method has the advantages over the other measuring method, such as nondestructive, higher accuracy and simple structure.