Polishing method, polishing monitoring method and polishing monitoring apparatus for workpiece

A polishing method for polishing a polishing-target layer of a workpiece, comprising:

• rotating a polishing table supporting a polishing pad;
• polishing the polishing-target layer by pressing the workpiece against the polishing pad;
• irradiating the workpiece with light;
• receiving reflected light from the workpiece;
• measuring an intensity of the reflected light at each of wavelengths;
• generating a spectral waveform showing a relationship between the intensity and wavelength of the reflected light;
• removing a noise from the spectral waveform by a filter;
• performing a Fourier transform process on the spectral waveform, from which the noise is removed, to generate a frequency spectrum;
• determining a thickness of the polishing-target layer based on a peak of the frequency spectrum;
• and
• complementing, by extrapolation, a thickness of the polishing-target layer corresponding to a peak of the frequency spectrum disappeared as a result of the removal of the noise, the extrapolation using a plurality of values of the thickness of the polishing-target layer obtained during polishing of the workpiece.

A polishing monitoring method for a workpiece, comprising:

• irradiating the workpiece with light during polishing of the workpiece;
• generating a spectrum of reflected light from the workpiece;
• calculating an amount of change in the spectrum per predetermined time;
• correcting the amount of change in the spectrum when the amount of change in the spectrum satisfies a predetermined exclusion condition;
• and
• calculating a cumulative amount of change in the spectrum by adding up an amount of change in the spectrum that does not satisfy the exclusion condition and the corrected amount of change in the spectrum along a polishing time.

A polishing monitoring apparatus for a workpiece, comprising:

• an optical sensor head configured to irradiate the workpiece with light and receive reflected light from the workpiece during polishing of the workpiece;
• a spectrometer configured to measure an intensity of the reflected light at each of wavelengths;
• and
• a data processor having a memory storing a program and an arithmetic device for performing arithmetic operations according to instructions included in the program, the data processor being configured to:
• generate a spectrum of the reflected light from an intensity measurement data of the reflected light;
• calculate an amount of change in the spectrum per predetermined time;
• correct the amount of change in the spectrum when the amount of change in the spectrum satisfies a predetermined exclusion condition;
• and
• calculate a cumulative amount of change in the spectrum by adding up an amount of change of the spectrum that does not satisfy the exclusion condition and the corrected amount of change in the spectrum along a polishing time.