Optical measurement apparatus, measuring method using the same, and method for fabricating semiconductor device using the same

An optical measurement apparatus comprising:

• a light source which generates light;
• an optical system including an objective lens which converts light generated by the light source and received from a measurement target into parallel light and outputs the parallel light to output a pupil image of the measurement target;
• a polarization generator which generates a polarized light from the parallel light;
• a self-interference generator which generates a plurality of beams divided from the pupil image, using the polarized light;
• a detector which detects a self-interference image generated by the plurality of beams interfering with each other;
• and
• an image analysis unit configured to extract phase data from the self-interference image and adjust a distance between the measurement target and the optical system on the basis of the phase data.

An optical measurement apparatus comprising:

• a light source which generates light including a broadband light;
• a beam splitter which makes the light incident on a measurement target, and emits any one of light reflected from the measurement target, light transmitted from the measurement target, and light refracted from the measurement target;
• an objective lens which condenses the light from the measurement target and generates a pupil image of the measurement target from the light from the measurement target, wherein the objective lens is between the measurement target and the pupil image;
• a wavelength selector which receives the light from the objective lens and which outputs at least one monochromatic light from the light received from the objective lens, wherein the light received from the object lens is parallel light;
• a polarization generator which polarizes the monochromatic light in a first direction to generate a polarized light;
• a self-interference generator which includes a beam displacer that generates a plurality of beams divided from the pupil image by the use of the polarized light, and an analyzer that polarizes the plurality of beams in a second direction;
• a detector which detects a self-interference image generated by the plurality of beams interfering with each other;
• and
• an image analysis unit configured to extract a phase difference from the self-interference image, and adjust a distance between the measurement target and the objective lens on the basis of the phase difference,
• wherein the wavelength selector, polarization generator, and self-interference generator are all optically between the objective lens and the detector.