US 5,686,993 A · Method of and apparatus for measuring film thickness

Abstract

A film thickness measuring apparatus measures the thickness of a thin film which is formed on a substrate with an excellent reproducibility regardless of inclination of a surface of a sample. Since an illumination system (20) includes a glass rod (GL) which corrects wavelength dependencies of luminance distributions of light sources (HL, DL), even when an eclipse in reflected light due to inclination of a sample (SP) decreases the energy of the reflected light, a spectral distribution of the reflected light entering a spectroscopic unit (40) is maintained with almost no change. A control unit (50) performs data conversion of multiplying an actual spectral reflectance by a ratio of an average of the actual spectral reflectance which is determined based on an output from the spectroscopic unit (40) to an average of a calibrated spectral reflectance and thereafter calculates a deviation between the two spectral reflectances. As a result, the film thickness is accurately measured while preventing an influence of inclination of the sample (SP).

Claims10

Dependent claims

A film thickness measuring apparatus, comprising

an illumination system having a light source for illuminating a sample in which a thin film is formed on a substrate,
an imaging system for converging reflected light which is reflected by said sample,
a spectroscopic system for obtaining spectral signals of said reflected light through said imaging system,
calculation means for calculating actual spectral reflectances of said thin film from said spectral signals, and for determining the film thickness of said thin film by means of comparison of said actual spectral reflectances with calibrated spectral reflectances, said calibrated reflectances being theoretically calculated from optical data of said thin film, and
secondary light source forming means for correcting wavelength dependence of luminance distribution on said light source, wherein
said calculation means determines the film thickness of said thin film after converting at least one of said actual spectral reflectances and said calibrated spectral reflectances in such a manner that an average value of said actual spectral reflectances is equal to an average value of said calibrated spectral reflectances.

3 more elements

Dependencies are inferred from the claim text.

Method of and apparatus for measuring film thickness

Life of this patent

Method of and apparatus for measuring film thickness

Life of this patent

Abstract

Claims10