Method for measuring thickness and optical properties of multi-layer film

A method for measuring a thickness and optical properties of a multi-layer film, comprising:

• step 1:
• depositing films on a substrate to form a multi-layer film in sequence, wherein the films of the multi-layer film are classified into a diamond-like film and a diamond film;
• step 2:
• measuring an ellipsometric spectrum of the multi-layer film;
• step 3:
• judging whether each film layer of the multi-layer film is the diamond film or the diamond-like film;
• when the film layer of the multi-layer film is the diamond film, step 41 is executed;
• when the film layer of the multi-layer film is the diamond-like film, steps 42, 5, and 6 are executed;
• step 41:
• obtaining optical constants and a thickness of the film layer of the multi-layer film by calculating using Cauchy model in a full spectral region;
• step 42:
• selecting a spectral region defining a transparent section of the film layer of the multi-layer film, and obtaining optical constants and a thickness of the film layer of the multi-layer film by calculating using Cauchy model in the spectral region;
• step 5:
• adding an oscillator model for dielectric constants to an absorption spectrum region of the diamond-like film, and adjusting an amplitude and a width of the oscillator model according to the ellipsometric spectrum;
• and
• step 6:
• evaluating a difference between an experimental value and a fitted value by using an evaluation function mean squared error (MSE) to determine a structure of the multi-layer film and optical constants and a thickness of each film layer of the multi-layer film,
• wherein the optical constants comprise refractive index n and extinction coefficient k.