Optical element support structure, unit mirror group, exposure optical system and photolithography machine

Abstract

The invention discloses an optical element supporting structure, which is used for supporting an optical element (22) of a unit lens group (21), including a mirror seat (24), and the mirror seat (24) is a circularly symmetrical mechanical component. The inner ring of the mirror base (24) protrudes a support rod (246) toward the center of the mirror base, and the support rod (246) is flexible in the optical axis direction and the radial direction of the mirror base, and the end of the support rod (246) is provided with a supporting surface (247), the supporting surface (247) matches the lower surface of the optical element (22) to fix the optical element (22) on the mirror holder (24); the supporting rod (246) The inboard side is connected with a moving table (245), and the moving table (245) is connected with the outer ring of the mirror holder (24) by a guiding mechanism (243), and the described guiding mechanism (243) is used for the movement of the moving platform (245). motion oriented.

Description

technical field [0001] The invention belongs to the technical field of high-precision optical lens manufacturing and assembly, and in particular relates to a support structure for an optical element capable of compensating surface shape, a unit lens group, an exposure optical system and a photolithography machine. Background technique [0002] The design, processing, manufacture and adjustment of high-end lithography projection objective lens is a very precise and complex system engineering. With the extension of Moore's Law, the semiconductor industry has higher and higher requirements for the minimum line width resolution of processor chips. In order to achieve high-quality imaging performance and higher resolution, the RMS value of the surface shape accuracy of optical components is required to reach 1nm ~2nm level. As the NA value of the projection objective optical system of the lithography machine gradually increases, the clear aperture of the optical components in th...

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Problems solved by technology

Patent US6392825B1 discloses a mirror frame structure with multiple elastic support units, which can offset the influence of external stress and deformation through the elasticity of the support units; since the elastic support units are processed by thin plate materials, it is difficult to achieve micron-level processing accuracy, and the elastic support The unit and the mirror frame are connected by welding or screw fastening, and the welding stress and screw preload will also reduce the final precision of the elastic support unit

Patent US6229675B1 proposes a structural form that decouples the deformation of the inner and outer frames. This structure has poor processability and is a passive compensation method. Although it can eliminate the influence of external stress on the surface shape accuracy of optical elements, it cannot compensate for dynamics. Surface error

Patent US7031082B2 discloses a mirror frame structure capable of deforming optical elements, and also equipped with a deformation monitoring unit. However, the deformation adjustment part of this structure is assembled from multiple parts, which is complex in structure and difficult to assemble and adjust. Shape tuning with nanoscale precision

Patent US7193794B2 discloses a mirror frame structure that actively compensates the surface shape error of the optical element, which can compensate the influence of astigmatism and trilobes on the imaging performance of the system without changing the spatial position of the optical element; however, this method is axially The driver or transmission structure is arranged in the direction of the optical axis, which takes up a lot of space, and it is difficult to adjust the force of the optical element at each support point, and it cannot be used for surface shape compensation of more optical elements in the same objective lens

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