Patent ID: 8554356

Claim:
A processing end point detection method for detecting a processing end point based on a characteristic value with respect to a surface of a workpiece, the characteristic value being calculated using a spectral waveform of reflected light obtained by applying light to the surface of the workpiece, said method comprising: producing a reference spectral waveform indicating a relationship between reflection intensities and wavelengths at a processing end point of a surface of a reference workpiece; based on the reference spectral waveform, selecting wavelengths of a local maximum value and a local minimum value of the reflection intensities at the processing end point of the reference workpiece prior to processing a workpiece; calculating a characteristic value with respect to the surface of the reference workpiece from the reflection intensities at the selected wavelengths; setting a distinctive point of time variation of the characteristic value at the processing end point of the reference workpiece as a processing end point of a workpiece; processing a surface of the workpiece that corresponds to the surface of the reference workpiece while monitoring a characteristic value of the surface of the workpiece; and detecting the processing end point of the workpiece by detecting the distinctive point of time variation during the processing of the workpiece.