Fully-spherical deep ultraviolet lithography objective

Abstract

The invention relates to a fully-spherical deep ultraviolet lithography objective and belongs to the technical field of high-resolution projection lithography objectives. The invention provides the deep ultraviolet lithography objective with lighting system operation wavelength of 193nm and numerical aperture of 0.75; the objective has a compact structure, large field view and high imaging quality, and reduces processing difficulty because all lenses are in a spherical shape; the objective comprises front and back lens groups, totally 29 fully-spherical lenses; the lens is made from fused quartz and calcium fluoride, wherein the calcium fluoride is used for correcting chromatic aberration; both sides of the system are telecentric and have extremely high telecentricity; and the radius and thickness of each lens element and the space between lens elements are optimized so as to better compensate aberration and obtain good structural parameters, so that the distortion of the image quality is less than 1nm and wave aberration is less than 3nm. The fully-spherical deep ultraviolet lithography objective can be applied to a deep ultraviolet projection lithography device with lighting source wavelength of 193nm.

Description

technical field [0001] The invention relates to a deep ultraviolet spherical lithography objective lens, which belongs to the technical field of high-resolution projection lithography objective lens. Background technique [0002] Photolithography is an integrated circuit manufacturing technology that uses optical methods to transfer the circuit pattern on the mask plate to the silicon wafer. Almost all integrated circuits are manufactured using optical lithography. Initially, semiconductor devices were manufactured using contact lithography technology in which masks were attached to silicon wafers. In 1957, contact lithography technology realized the manufacture of DRAM (Dynamic Random Access Memory) with a feature size of 20 μm. After that, the semiconductor industry introduced proximity lithography technology with a certain gap between the mask and the silicon wafer, and DRAMs with feature sizes of 10 μm and 6 μm were manufactured in 1971 and 1974, respectively. In 1977,...

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Problems solved by technology

[0004] In order to solve the problem of low resolution of the existing projection lithography objective lens and the difficulty of processing, the present invention proposes a deep ultraviolet lithography objective lens with an illumination system whose working wavelength is 193nm and whose numerical aperture reaches 0.75. The objective lens has a compact structure, Large field of view, excellent imaging quality, all lens surfaces are spherical, which reduces the difficulty of processing

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