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AssigneeNikon Corporation
InventorTakehisa Yahiro
Estimating the term…
Methods and devices are provided for performing adjustments of illumination uniformity obtained from a charged-particle illumination-optical system as used, e.g., in a charged-particle-beam (CPB) microlithography apparatus. The adjustments are based on measurements of illumination-beam current density. The device includes an aperture plate (desirably a silicon membrane), defining a tiny measurement aperture (desirably about 1 μm diameter), mounted on the reticle stage at the reticle plane. The illumination beam is scanned over the aperture. Charged particles of the beam passing through the aperture are directed to a beam-current detector on or at the substrate stage. The membrane desirably has a thickness of about 1 to 3 μm. The measurement aperture allows the distribution of current density of the illumination beam to be measured highly accurately. The thinness of the membrane allows the membrane to scatter incident CPB radiation rather than absorbing the radiation, thereby preventing thermal deformation of the membrane.
In a charged-particle-beam (CPB) microlithography apparatus in which an illumination beam, generated by a CPB source including a CPB-emission surface, passes through an illumination-optical system and illuminates a region of a patterned reticle situated on a reticle stage to produce an imaging beam directed by a projection-optical system to a substrate situated on a substrate stage, a device for measuring an illumination uniformity of the illumination beam as incident on the reticle, the device comprising:
Dependencies are inferred from the claim text.