| 摘要 |
Methods are provided for performing axial alignment of the optical system in a charged-particle-beam (e.g., electron-beam) microlithographic exposure apparatus employing an illumination beam and a scattering-type reticle. The microlithographic exposure apparatus projects and forms an image of a patterned beam that has passed through a reticle onto a substrate (e.g., semiconductor wafer). The reticle can be a scattering-stencil mask in which feature-defining cutouts are formed in a membrane that transmits an illumination beam while scattering the beam. A contrast aperture is disposed at the beam-convergence plane of the projection lens, i.e., at the Fourier plane of the reticle surface. Axial alignment is performed using an adjustment reticle having a "white subfield" (in a scattering-stencil reticle, a cutout area covering the entire subfield) and a "black subfield" (in a scattering-stencil reticle, a subfield consisting entirely of a reticle membrane lacking any cutouts).
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