Exposure apparatus and device manufacturing method

An exposure apparatus comprising:

• an original stage configured to hold an original;
• a substrate stage configured to hold a substrate;
• an illumination optical system configured to illuminate the original with light from a light source;
• a projection optical system configured to project light from the original illuminated by the illumination optical system to the substrate to perform an exposure of the substrate to light;
• a first reflecting member configured to reflect light at a first position on an optical path of the exposure;
• a second reflecting member configured to reflect light at a second position on the optical path, wherein an optical element exists between the first and second positions;
• a detector configured to detect first reflected light from the first reflecting member and second reflected light from the second reflecting member, each produced by illumination with light from the light source;
• and
• a processor configured to obtain intensities of the first reflected light and the second reflected light based on an output from the detector, and to calculate a transmittance of the optical element based on the obtained intensities.

A method of manufacturing a device, the method comprising:

• exposing a substrate to light using an exposure apparatus;
• developing the exposed substrate;
• and
• processing the developed substrate to manufacture the device,
• wherein the exposure apparatus includes
• an original stage configured to hold an original;
• a substrate stage configured to hold a substrate;
• an illumination optical system configured to illuminate the original with light from a light source;
• a projection optical system configured to project light from the original illuminated by the illumination optical system to the substrate to expose the substrate to light;
• a detector configured to detect first reflected light from a first reflecting member disposed on the original stage and second reflected light from a second reflecting member disposed on the substrate stage produced by illumination with light from the light source, wherein either the first or second reflected light travels forward via the projection optical system and backward via the projection optical system, and is detected by the detector;
• and
• a processor configured to obtain intensities of the first reflected light and the second reflected light based on an output from the detector, and to calculate transmittance of the projection optical system based on the obtained intensities.

A method of manufacturing a device, the method comprising:

• exposing a substrate to light using an exposure apparatus;
• developing the exposed substrate;
• and
• processing the developed substrate to manufacture the device,
• wherein the exposure apparatus includes:
• an original stage configured to hold an original;
• a substrate stage configured to hold a substrate;
• an illumination optical system configured to illuminate the original with light from a light source;
• a projection optical system configured to project light from the original illuminated by the illumination optical system to the substrate to perform an exposure of the substrate to light;
• a first reflecting member configured to reflect light at a first position on an optical path of the exposure;
• a second reflecting member configured to reflect light at a second position on the optical path, wherein an optical element exists between the first and second positions;
• a detector configured to detect first reflected light from the first reflecting member and second reflected light from the second reflecting member, each produced by illumination with light from the light source;
• and
• a processor configured to obtain intensities of the first reflected light and the second reflected light based on an output from the detector, and to calculate a transmittance of the optical element based on the obtained intensities.