Method and apparatus for measuring the thickness of a thin film using the spectral reflection factor of the film

A device, usable with an object having a layer, for measuring the thickness of the layer of the object, said method comprising the steps of:

• irradiating the object with light of a plurality of wavelengths;
• measuring the spectral reflectance associated with the object irradiated with the light, the spectral reflectance oscillating with a change in the wavelength of the light;
• correcting the amplitude and the center of the oscillation of the spectral reflectance measured, in accordance with a property of the layer of the object;
• and
• determining the thickness of the layer in accordance with the corrected spectral reflectance.

A device, usable with an object having a layer, for measuring the thickness of the object, said method comprising the steps of:

• irradiating the object with light of a plurality of wavelengths;
• detecting the light of a plurality of wavelengths from the irradiated object;
• calculating, first, the approximate thickness of the layer on the basis of the detection of the light from the object;
• and
• calculating, second, the thickness of the layer on the basis of the approximate thickness determined by the first calculation step;
• wherein said second calculation step is repeated while using the thickness calculated in said second calculation step itself as an approximate thickness for calculating a new thickness of the layer, until the difference between the result of the last calculation performed by repeating said second calculation step and the result of the penultimate calculation is not greater than a predetermined value.

A method, usable with an object having a layer, for measuring the thickness of the layer of the object, said method comprising the steps of:

• irradiating a first portion of the object with light of a plurality of wavelengths;
• detecting the light of a plurality of wavelengths from the first portion of the object being irradiated;
• irradiating a second portion of the object with light of a plurality of wavelengths;
• detecting the light of a plurality of wavelengths from the second portion of the object being irradiated;
• and
• determining the thickness of the layer with respect to the first portion thereof on the basis of the detection of the light from the first portion, during a time period in which the second portion of the object is irradiated.

A method, usable with an object having a layer, for measuring the thickness of the layer of the object, said method comprising the steps of:

• irradiating the object with light of a plurality of wavelengths;
• detecting the intensity of each wavelength of the light from the object being irradiated;
• selecting at least one of the detected intensities that satisfies one of first and second predetermined conditions, wherein said first predetermined condition is that the light intensity at its extremum is larger than a first reference value and wherein said second predetermined condition is that of the light intensity at its extremum is smaller than a second reference value;
• and
• determining the thickness of the layer on the basis of said at least one selected intensity and the wavelength corresponding to said selected intensity.