Apparatus for measuring film thickness formed on object, apparatus and method of measuring spectral reflectance of object, and apparatus and method of inspecting foreign material on object
View Patent ↗A film thickness measurement apparatus ( 1 ) comprises an ellipsometer ( 3 ) for acquiring a polarization state of a film on a substrate ( 9 ) and a light interference unit ( 4 ) for acquiring spectral intensity of the film on the substrate ( 9 ). In an optical system ( 45 ) of the light interference unit ( 4 ), a light shielding pattern ( 453 a ) is disposed in an aperture stop part ( 453 ), and an illumination light from a light source ( 41 ) is emitted to the substrate ( 9 ) through the optical system ( 45 ). A reflected light from the substrate ( 9 ) is guided to a light shielding pattern imaging part ( 43 ), where an image of the light shielding pattern ( 453 a ) is acquired. When the ellipsometer ( 3 ) performs a film thickness measurement, a tilt angle of the substrate ( 9 ) is obtained on the basis of the image of the light shielding pattern ( 453 a ) and a light receiving unit ( 32 ) acquires a polarization state of the reflected light. An calculation part ( 51 ) obtains a thickness of a film with high precision from the polarization state of the reflected light by using the obtained tilt angle.
1. A film thickness measurement apparatus fox measuring a thickness of a film formed on an object, comprising:
a first light source for emitting a polarized light to an object;
a light receiving part for receiving a reflected light of said polarized light from said abject to acquire a polarization state of said reflected light;
an calculation part for obtaining a thickness of a film on said object on the basis of said polarization state;
a second light source for emitting an illumination light;
an optical system for guiding said illumination light to said object and guiding a reflected light of said illumination light from said object to a predetermined position;
a light shielding pattern disposed at a position almost optically conjugate to an aperture stop position on an optical path from said second light source to said object; and
an imaging part for acquiring an image of said light shielding pattern formed on said predetermined position,
wherein said calculation part obtains a tilt angle of said object on the basis of an output from said imaging part and obtains a thickness of said film from said polarization state, by using said tilt angle.
2. The film thickness measurement apparatus according to claim 1 , further comprising:
a filter disposed at a position almost optically conjugate to a field stop position on an optical path from said second light source to said object,
wherein said filter cuts off a light of at least specific wavelength at a portion out of a portion corresponding to a microscopic region on said object.
3. The film thickness measurement apparatus according to claim 1 , wherein
said calculation part obtains said tilt angle on the basis of a vector between a predetermined reference position and a barycentric position of an image of said light shielding pattern in an image indicated by said output from said imaging part.