| 摘要 |
PROBLEM TO BE SOLVED: To provide an apparatus which accurately measures the thickness of a thin film having the thickness of about micro meters or less, in measuring the thickness of the opaque thin film. SOLUTION: As a laser stimulation light utilized in a resonance method, beat light prepared by the interference of two laser beams of light having different wavelengths is utilized. The stimulation light in which the intensity varies at an extremely high frequency is prepared, thereby coping with the measurement on the thickness of a thin film of micrometers or less. According to the utilization of the resonance method, the information of repeated echo interval is efficiently utilized. In the device, there is no need for accurately controlling the frequency of a frequency variable continuous laser which is used for varying the beat frequency. COPYRIGHT: (C)2004,JPO
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