| 主权项 |
1. A lithography apparatus that forms a pattern on a substrate, the apparatus comprising:
a measurement unit configured to measure an amount of overlay shift between a first mark formed on a first surface of the substrate and a second mark formed on a second surface opposite to the first surface, the measurement unit including: an optical system configured to illuminate the substrate from a side of the first surface with light of a wavelength transmitted by the substrate, and form an image of the first mark with light returning from the first surface and an image of the second mark with light returning from the second surface; a sensor configured to detect each of the image of the first mark and the image of the second mark; and a processor configured to perform processing of deciding a measurement focus position of the optical system at which the sensor can detect both the image of the first mark and the image of the second mark based on first mark detection information obtained in a focus state of the optical system in which the sensor can detect the image of the first mark, and second mark detection information obtained in a focus state of the optical system in which the sensor can detect the image of the second mark, detecting the image of the first mark and the image of the second mark by the sensor in a first focus state of the optical system in which a focus position of the optical system exists at the measurement focus position, and obtaining a position of the first mark on the first surface and a position of the second mark on the second surface based on the image of the first mark and the image of the second mark that have been detected in the first focus state. |
