Illumination correction apparatus
An illumination correction apparatus for correcting a radiation beam incident on a reticle from an exposure apparatus includes a plurality of fingers each having a surface facing an incident direction of the radiation beam, the plurality of fingers being arranged in a first direction to be adjacent to a path of the radiation beam, and configured to adjust an amount of the incident radiation beam by moving in a second direction, intersecting the first direction, a controller connected to the plurality of fingers and configured to control movement of the plurality of fingers such that an intensity of the radiation beam has uniformity in the first direction, at least one optical sensor on the surface of at least one finger of the plurality of fingers, and a measurement unit configured to measure, based on an output of the at least one optical sensor, the intensity of the radiation beam.
1. An illumination correction apparatus configured to correct a radiation beam incident on a reticle from an exposure apparatus, the illumination correction apparatus comprising:
a plurality of fingers each having a surface facing an incident direction of the radiation beam, the plurality of fingers being arranged in a first direction to be adjacent to a path of the radiation beam, and configured to adjust an amount of the incident radiation beam by moving in a second direction intersecting the first direction;
a controller connected to the plurality of fingers, and configured to control movement of the plurality of fingers such that an intensity of the radiation beam has uniformity in the first direction;
a plurality of optical sensors comprising a first optical sensor and a second optical sensor on the surface of a finger of the plurality of fingers; and
a measurement unit configured to:
measure the intensity of the radiation beam based on an output of the plurality of optical sensors, and
calibrate the intensity of the radiation beam based on a comparison between an output of the first optical sensor and an output of the second optical sensor.
2. The illumination correction apparatus of claim 1 , wherein:
each of the plurality of fingers further comprises a distal edge adjacent to the path of the radiation beam, and
the plurality of optical sensors are on a surface of the finger and are spaced apart from the distal edge by a first distance in the second direction.
3. The illumination correction apparatus of claim 2 , wherein:
the controller is configured to control the plurality of fingers to move an exposure distance in an exposure mode, and to control the plurality of fingers to move a measurement distance, greater than the exposure distance in a measurement mode, and
the first distance is greater than the exposure distance and is less than the measurement distance.
4. The illumination correction apparatus of claim 1 , wherein:
each of the plurality of fingers further comprises a distal edge adjacent to the path of the radiation beam, and
the first optical sensor is on the surface of the finger spaced apart from the distal edge by a first distance in the second direction, and the second optical sensor is on the surface of the finger spaced apart from the distal edge by a second distance greater than the first distance in the second direction.
5. The illumination correction apparatus of claim 4 , wherein:
the controller is configured to control the plurality of fingers such that the first optical sensor is exposed to the radiation beam and the second optical sensor is not exposed to the radiation beam in a measurement mode, and to control the plurality of fingers such that the first optical sensor and the second optical sensor are exposed to the radiation beam in a calibration mode.
6. The illumination correction apparatus of claim 1 , wherein the illumination correction apparatus further comprises:
a support configured to surround the plurality of fingers in the first direction, the support having a surface facing the incident direction of the radiation beam; and
at least one energy sensor on the surface of the support.
7. The illumination correction apparatus of claim 1 , wherein the plurality of optical sensors comprises a photodiode configured to perform photoelectric conversion on a radiation beam of 10 nm to 30 nm.
8. The illumination correction apparatus of claim 1 , wherein the illumination correction apparatus further comprises a plurality of optical filters attached to a surface of the plurality of optical sensors.
9. The illumination correction apparatus of claim 8 , wherein the plurality of optical filters are configured to selectively transmit an extreme ultraviolet (EUV) beam.
10. The illumination correction apparatus of claim 1 , wherein the illumination correction apparatus further comprises Peltier devices on a surface of the plurality of optical sensors oriented toward the at least one finger.
11. The illumination correction apparatus of claim 1 , wherein the measurement unit is configured to output, based on the output of the plurality of optical sensors, an intensity profile representing the intensity of the radiation beam depending on a position of the radiation beam in the first direction.
12. The illumination correction apparatus of claim 11 , wherein the controller is configured to control, based on the intensity profile output by the measurement unit, the movement of the plurality of fingers such that the intensity of the radiation beam has uniformity in the first direction.
13. The illumination correction apparatus of claim 1 , wherein the measurement unit comprises:
a signal amplifier configured to generate a current signal or a voltage signal by amplifying a signal photoelectrically converted from the plurality of optical sensors; and
a detector configured to determine, based on the current signal or the voltage signal, the intensity of the radiation beam.
14. The illumination correction apparatus of claim 1 , wherein a respective one of the plurality of optical sensors is on a surface of each of the plurality of fingers.
15. The illumination correction apparatus of claim 1 , wherein a respective one of the plurality of optical sensors is on a surface of some of the plurality of fingers.
16. The illumination correction apparatus of claim 1 , wherein each of the plurality of optical sensors has a length of 1 μm or more and 1 cm or less in the first direction.
17. An illumination correction apparatus configured to correct a radiation beam incident on a reticle from an exposure apparatus, the illumination correction apparatus comprising:
a plurality of fingers configured to adjust an intensity of the radiation beam incident on the reticle with movement of the plurality of fingers in a predetermined direction;
an energy sensor adjacent to the plurality of fingers; and
a plurality of optical sensors on a surface of at least one finger, among the plurality of fingers,
wherein the illumination correction apparatus is configured to determine a relation between the intensity at opposite ends of the radiation beam and the intensity of a main portion of the radiation beam, and measure the intensity at the opposite ends of the radiation beam using the energy sensor, and estimate, based on the relation, the intensity of the main portion of the radiation beam, and
the intensity of the radiation beam on the reticle level is used to monitor energy transmission efficiency of a projection system of the exposure apparatus.
18. The illumination correction apparatus of claim 17 , wherein the illumination correction apparatus is configured to control the plurality of fingers such that the plurality of optical sensors are not exposed to the radiation beam incident on the reticle in an exposure mode, and to control the plurality of fingers such that the plurality of optical sensors are exposed to the radiation beam in a measurement mode.
19. The illumination correction apparatus of claim 18 , wherein the illumination correction apparatus is configured to:
in the measurement mode, measure an intensity at opposite ends of the radiation beam using the energy sensor, measure an intensity in a main portion of the radiation beam using the plurality of optical sensors, and determine a proportional constant between the intensity at the opposite ends of the radiation beam and the intensity of the main portion of the radiation beam; and
in the exposure mode, measure the intensity at the opposite ends of the radiation beam using the energy sensor, and estimate, based on the proportional constant, the intensity of the main portion of the radiation beam.
20. An illumination correction apparatus configured to correct a radiation beam incident on a reticle from an exposure apparatus, the illumination correction apparatus comprising:
a plurality of fingers configured to adjust an amount of the radiation beam incident on the reticle with movement of the plurality of fingers in a predetermined direction;
an energy sensor adjacent to the plurality of fingers; and
a plurality of optical sensors comprising a first optical sensor and a second optical sensor on a surface of a finger, among the plurality of fingers,
wherein the illumination correction apparatus is configured to measure a reticle-level intensity profile representing a position-dependent intensity of the radiation beam incident on the reticle using the energy sensor and the plurality of optical sensors, and to calibrate the intensity of the radiation beam based on a comparison between an output of the first optical sensor and an output of the second optical sensor, and
wherein the reticle-level intensity profile is used to monitor whether there is an abnormality in aberration or alignment of a projection system.