| 摘要 |
PROBLEM TO BE SOLVED: To provide an etching amount calculating method which can stably and accurately calculate the amount of etching even if a disturbance is added. SOLUTION: In the etching of a wafer W which forms a trench 132 using a mask film 131, laser beam L1 is irradiated on the wafer W. Superposed interference wave is calculated by receiving the superposed interference light resulting from superposition of mask film interference light and trench interference light. A waveform of a window which defines the present timing T as the endpoint is extracted. Max entropy method is used for the waveform of the window, and the trench interference light is detected from frequency distribution obtained by performing frequency analysis. While shifting the endpoint of the window by onlyΔt, the calculation of the superposed interference wave, the extraction of the waveform of the window, the frequency analysis of the wave form of the window, and the detection of the trench interference period are repeated, and the detected trench interference periods are integrated and averaged at each repetition. The etching amount of the trench 132 is calculated based on the integrated and averaged trench interference periods. COPYRIGHT: (C)2009,JPO&INPIT
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