Apparatus and method of measuring uniformity based on pupil image and method of manufacturing mask by using the method
An apparatus and method of measuring pattern uniformity, and a method of manufacturing a mask by using the measurement method are provided. The measurement apparatus includes a light source configured to generate and output light, a stage configured to support a measurement target, an optical system configured to transfer the light, output from the light source, to the measurement target supported on the stage, and a first detector configured to detect light reflected and diffracted by the measurement target, or diffracted by passing through the measurement target, wherein the first detector is configured to detect a pupil image of a pupil plane and to measure pattern uniformity of an array area of the measurement target on the basis of intensity of at least one of zero-order light and 1 st -order light of the pupil image.
1. A method of measuring pattern uniformity on the basis of a pupil image, the method comprising:
generating and outputting light by using a light source;
transferring, by using an optical system, the light from the light source to a measurement target disposed on a stage, wherein the measurement target comprises an array area of repeating patterns;
detecting, by using a first detector, light reflected and diffracted by the measurement target or light diffracted by passing through the measurement target; and
measuring pattern uniformity of the repeating patterns of the array area of the measurement target on the basis of the light detected by the first detector, wherein
the detecting of the light comprises detecting a pupil image of a pupil plane by using the first detector, and
the measuring of the pattern uniformity of the repeating patterns comprises measuring the pattern uniformity of the repeating patterns on the basis of detecting the intensity of at least one of zero-order light and 1st-order light of the pupil image.
2. The method of claim 1 , wherein:
the measurement target comprises a mask,
the first detector detects a pupil image of light diffracted by passing through the mask, and a size of one shot of the first detector is about 40 μm*40 μm,
the method further comprises, before the measuring of the pattern uniformity,
selecting the pupil image,
the selecting of the pupil image comprises, based on that a diffraction angle of diffracted light in the array area differs from a diffraction angle of diffracted light in an area other than the array area, determining whether the pupil image includes only the array area or at least a portion of the area other than the array area, and selecting the pupil image including only the array area, and
the measuring of the pattern uniformity comprises using the selected pupil image including only the array area in measuring the pattern uniformity.
3. The method of claim 2 , wherein:
the first detector comprises a charge coupled device (CCD) or a photo multiplier tube (PMT),
the detecting of the light comprises sensing the intensity of the zero-order light, the intensity of the 1 st -order light, or the intensities of the zero-order light and the 1 st -order light by using the first detector, and
the measuring of the pattern uniformity comprises calculating intensity as a gray scale and measuring the pattern uniformity of the array area on the basis of the gray scale.
4. The method of claim 1 , wherein:
the transferring of the light to the measurement target comprises splitting the light into first light and second light by using a beam splitter, irradiating the first light onto the measurement target, and irradiating the second light onto a second detector,
the detecting of the light comprises detecting, by using the second detector, a pupil image of the second light to sense fluctuation of the second light in real time, and
the measuring of the pattern uniformity comprises compensating a pupil image of the first light or compensating the pattern uniformity, based on information about the fluctuation of the second light.
5. The method of claim 1 , wherein:
a size of one shot of the first detector varies for each measurement target, based on a pattern of the array area,
the detecting of the light comprises detecting, by using the first detector, a pupil image corresponding to an entire surface of the measurement target through full scanning, or detecting, by using the first detector, a pupil image corresponding to each of set positions of the measurement target through sampling.
6. The method of claim 1 , further comprising,
before the transferring of the light to the measurement target, constructing a focus map corresponding to an entire surface of the measurement target,
wherein the detecting of the light comprises automatically performing focusing on the basis of the focus map, or the measuring of the pattern uniformity comprises reflecting the focus map in a measurement result of the pattern uniformity.
7. A method of manufacturing a mask, the method comprising:
preparing a mask having an array area of repeating patterns;
generating and outputting light by using a light source;
transferring, by using an optical system, the light from the light source to the mask disposed on a stage;
detecting, by using a first detector, light reflected and diffracted by the mask or light diffracted by passing through the mask; and
measuring pattern uniformity of the repeating patterns of the array area on the basis of the light detected by the first detector;
wherein the detecting of the light comprises detecting a pupil image of a pupil plane by using the first detector, and
wherein the measuring of the pattern uniformity of the repeating patterns is performed on the basis of detecting the intensity of at least one of zero-order light and 1 st -order light of the pupil image.
8. The method of claim 7 , wherein:
the first detector is configured to detect a pupil image corresponding to light diffracted by passing through the mask, and a size of one shot of the first detector is about 40 μm*40 μm,
the method further comprises, before the measuring of the pattern uniformity,
selecting the pupil image,
the selecting of the pupil image comprises, based on that a diffraction angle of diffracted light in the array area differs from a diffraction angle of diffracted light in an area other than the array area, determining whether the pupil image includes only the array area or the pupil image includes at least a portion of the area other than the array area and selecting the pupil image including only the array area, and
the measuring of the pattern uniformity comprises using the selected pupil image including only the array area.
9. The method of claim 7 , wherein:
the transferring of the light to the mask comprises splitting the light into first light and second light by using a beam splitter, irradiating the first light onto the mask, and irradiating the second light onto a second detector,
the method further comprises detecting, by using the second detector, a pupil image corresponding to the second light to sense fluctuation of the second light in real time, and
the measuring of the pattern uniformity comprises compensating a pupil image corresponding to the first light or compensating the pattern uniformity, based on information about the fluctuation of the second light.
10. The method of claim 7 , wherein:
a size of one shot of the first detector varies for each mask, based on a pattern of the array area,
the method comprises, before the transferring of the light to the mask,
constructing a focus map corresponding to an entire surface of the mask,
the detecting of the light comprises automatically performing focusing on the basis of the focus map, or the measuring of the pattern uniformity comprises reflecting the focus map in a measurement result of the pattern uniformity, and
the detecting of the light comprises detecting, by using the first detector, a pupil image corresponding to an entire surface of the mask through full scanning of the entire surface, or detecting, by using the first detector, a pupil image corresponding to each of set positions of the mask through sampling.
11. The method of claim 7 , further comprising, when the pattern uniformity is abnormal, analyzing a cause thereof, changing a process condition for a process of forming the array area, and preparing the mask.