Polishing apparatus and polishing method

A polishing method of polishing a surface to be polished of a material to be polished, which comprises:

• an image pickup step of picking up images of the surface to be polished of the material to be polished;
• a location determination step of determining a location at which a thickness of the surface to be polished is measured from two-dimensional image informations of the surface to be polished which are obtained at the image pickup step;
• and
• a thickness measurement step of measuring, at the location, the thickness of the surface to be polished of the material to be polished,
• wherein, during polishing, the images of the surface to be polished are picked up at different focal points at a time, one two-dimensional image information is selected from the obtained two-dimensional image information of the surface to be polished, the location is determined from the one two-dimensional image information while a thickness of the surface to be polished is measured by a thickness measuring means at the location.

A polishing method comprising:

• a step of polishing a surface to be polished of a material to be polished with a polishing head;
• a step of irradiating a predetermined region of the surface to be polished with a light bundle emitted from a light source;
• a step of receiving an interference light bundle from the predetermined region of the surface to be polished separately at a plurality of wavelengths;
• and
• a step of measuring a thickness of the surface to be polished utilizing spectral reflection intensities which are optical signals received separately at the plurality of wavelengths,
• wherein the step of measuring the thickness comprises:
• a first step of using a plurality of solutions of the thickness value calculated at separate wavelengths from at least three of the optical signals received separately at the plurality of wavelengths, selecting a combination of solutions of the thickness value which have values closest to each other from the plurality of solutions and determining an approximate thickness value of the surface to be polished from the selected combination of solutions of the thickness value;
• and a second step of using a plurality of solutions of the thickness value calculated at separate wavelengths from all the optical signals received separately at all the wavelengths, and determining a detailed thickness value by restricting a selection range by taking the approximate thickness value obtained at the first step as standard, in selecting the combination of solutions of the thickness value which have values closest to each other out of the plurality of solutions.

A polishing method comprising:

• a step of polishing a surface to be polished of a material to be polished with a polishing head;
• a step of irradiating a predetermined region of the surface to be polished of the material to be polished with a light bundle emitted from a light source;
• a step of receiving an interference light bundle from the predetermined region of the surface to be polished separately as a plurality of separate wavelengths;
• and
• a step of measuring a thickness of the surface to be polished from a ratio in reflection amplitude and a phase difference between P polarized light and S polarized light which are calculated from optical signals received at the plurality of wavelengths,
• wherein the step of measuring a thickness comprises:
• a first step of using a plurality of solutions of the thickness value obtained by comparing a first correlation table which represents theoretical relationship among a thickness value, a ratio in reflection amplitude and a phase difference between P polarized light and S polarized light at each separate wavelength with a ratio in reflection amplitude and a phase difference between the P polarized light and the S polarized light calculated from the measured optical signals received at the plurality of separate wavelengths, selecting a combination of solutions of the thickness value which have values closest to each other from the plurality of solutions, and determining an approximate thickness of the surface to be polished from the selected combination of solutions of the thickness value;
• and a second step of determining a detail thickness value by restricting a comparison range by taking the approximate thickness value obtained in the first step as a standard, in obtaining a thickness value by comparing a second correlation table which represents theoretical relationship among a thickness value, a ratio in reflection amplitude and phase difference between the P polarized light and the S polarized light at each separate wavelength at an interval of a thickness value smaller than that of the first correlation table with values of a ratio in reflection amplitude and a phase difference between the P polarized light and the S polarized light which are calculated from the measured optical signals received at the plurality of separate wavelengths.

A polishing apparatus comprising:

• a polishing head;
• a holding means which holds a material to be polished;
• a driving means which rotates the holding means;
• and
• a thickness measuring means which irradiates the material which is revolving with momentary white light to specify a location at which a thickness of the surface of the material is to be measured and, at the same time, measures the thickness at the location.