METHOD FOR MEASURING THICKNESS OF THIN FILM

• Main Authors: HONMA SUSUMU, OOTSUKI KUNIO
• Format: Patent
• Language: English
• Published: 01.06.1984
• Subjects: MEASURING; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS; MEASURING LENGTH, THICKNESS OR SIMILAR LINEARDIMENSIONS; PHYSICS; TESTING

PURPOSE:To enable measurement of a film thickness with good accuracy without damaging a sample surface by irradiating diagonally the light of which the wavelength changes continuously onto the surface of a film to be measured, and knowing the wavelengths of the two adjacent bright peaks produced by the interference of the light reflected from the surface of the film and the light reflected from the base thereof. CONSTITUTION:Light is irradiated from a spectroscope 1 at the wavelength changed continuously to 450-1,100nm onto the surface of a sample 2 inclined at 45 deg.. The light reflected from said surface is received in a luminous intensity detector 3, and the relation between each wavelength and the intensity of the reflected light is plotted. If the sample is assumed to be, for example, a selenium layer 5 deposited by evaporation on a conductive substrate 4, the interference condition of the light 11 reflected on the surface of the layer 5 and the light 12 reflected on the boundary between the layer 5 and the substrate 4 and transmitted through the layer 5 is given by the following equation [II]. In the equation II, d is the film thickness of the layer 5, thetai is an angle of refraction, n(lambdai) is the refractive index of the film dependent on the wavelength lambdai of the incident light, and m is 0, 1, 2, 3- integer. Therefore the film thickness (d) is determined by the equation [ I ] if the wavelengths of the adjacent two bright peaks interfering with each other are designated as lambdai, lambdai+1.