Line narrowing module, laser device, and electronic device manufacturing method

A line narrowing module configured to line-narrow pulse laser light having a wavelength in an ultraviolet range, the line narrowing module comprising:

• a grating configured to reflect pulse laser light incident thereon;
• and
• an expansion optical system including a plurality of prisms and configured to cause the pulse laser light to be incident on the grating while expanding a beam width of the pulse laser light,
• a first closest prism which is closest to the grating and a second closest prism which is second closest to the grating, in the expansion optical system, having temperature coefficients of refractive indices opposite in sign to each other, and
• an amount of change of an optical path length difference, in the expansion optical system, between a case in which a temperature difference in the second closest prism is 0.2° C. or less and a case in which the temperature difference is 0.5° C. or more and 10° C. or less being half or less of the wavelength of the pulse laser light, as defining a light ray at one end of the pulse laser light in an expansion direction as a first light ray, a light ray at the other end as a second light ray, and a difference between a sum of optical path lengths of the first light ray in the plurality of prisms and a sum of optical path lengths of the second light ray in the plurality of prisms as the optical path length difference.

A laser device comprising:

• a line narrowing module configured to line-narrow pulse laser light having a wavelength in an ultraviolet range;
• an output coupling mirror;
• and
• a laser chamber including a pair of discharge electrodes and arranged on an optical path of an optical resonator configured by the line narrowing module and the output coupling mirror,
• the line narrowing module including:
• a grating configured to reflect pulse laser light incident thereon;
• and
• an expansion optical system including a plurality of prisms and configured to cause the pulse laser light to be incident on the grating while expanding a beam width of the pulse laser light,
• a first closest prism which is closest to the grating and a second closest prism which is second closest to the grating, in the expansion optical system, having temperature coefficients of refractive indices opposite in sign to each other, and
• an amount of change of an optical path length difference, in the expansion optical system, between a case in which a temperature difference in the second closest prism is 0.2° C. or less and a case in which the temperature difference is 0.5° C. or more and 10° C. or less being half or less of the wavelength of the pulse laser light, as defining a light ray at one end of the pulse laser light in an expansion direction as a first light ray, a light ray at the other end as a second light ray, and a difference between a sum of optical path lengths of the first light ray in the first closest prism and the second closest prism and a sum of optical path lengths of the second light ray in the first closest prism and the second closest prism as the optical path length difference.

An electronic device manufacturing method, comprising:

• generating pulse laser light using a laser device;
• outputting the pulse laser light to an exposure apparatus;
• and
• exposing a photosensitive substrate to the pulse laser light in the exposure apparatus to manufacture an electronic device,
• the laser device including:
• a line narrowing module configured to line-narrow pulse laser light having a wavelength in an ultraviolet range;
• an output coupling mirror;
• and
• a laser chamber including a pair of discharge electrodes and arranged on an optical path of an optical resonator configured by the line narrowing module and the output coupling mirror, and
• the line narrowing module including:
• a grating configured to reflect the pulse laser light incident thereon;
• and
• an expansion optical system including a plurality of prisms and configured to cause the pulse laser light to be incident on the grating while expanding a beam width of the pulse laser light,
• a first closest prism which is closest to the grating and a second closest prism which is second closest to the grating, in the expansion optical system, having temperature coefficients of refractive indices opposite in sign to each other, and
• an amount of change of an optical path length difference, in the expansion optical system, between a case in which a temperature difference in the second closest prism is 0.2° C. or less and a case in which the temperature difference is 0.5° C. or more and 10° C. or less being half or less of the wavelength of the pulse laser light, as defining a light ray at one end of the pulse laser light in an expansion direction as a first light ray, a light ray at the other end as a second light ray, and a difference between a sum of optical path lengths of the first light ray in the first closest prism and the second closest prism and a sum of optical path lengths of the second light ray in the first closest prism and the second closest prism as the optical path length difference.