| 摘要 |
PROBLEM TO BE SOLVED: To make the thickness of a transparent film and the film thickness distribution accurately measurable by frequency and phase-analyzing a spectral distribution waveform of a reflected light from a thin film and calculating an absolute value of the thickness from the relationship between a frequency and a phase component and the thickness. SOLUTION: A white light from a light source 41 is passed through a pinhole 42 and a beam splitter 45, converted into parallel beams via a lens 46, then passed through an iris diaphragm 47, and is incident to a film to be measured on a surface of a wafer 48. A reflected light of the wafer 48 is passed through the diaphragm 47 and the lens 46, altered at its optical path via the splitter 45, and is incident to a diffraction grating 44. The light spectrally separated by the grating 44 is focused on a detector 43, and hence a spectral intensity distribution 37 can be obtained. This reflected light is interfered via the film to be measured and is provided with a spectral intensity distribution corresponding to a structure in the film. This distribution is corrected and frequency analyzed by a processor 49, and hence its thickness is calculated. |
