A Catadioptric Projection Objective Based on High Numerical Aperture

Abstract

The invention discloses a catadioptric projection objective lens based on a high numerical aperture and aims to realize imaging of a pattern on a mask onto an image plane. The catadioptric projection objective lens comprises a first lens set, a second lens set and a third lens set, wherein the first lens set, the second lens set and the third lens set are coaxially arranged, the first lens set has positive focal power, the second lens set and the third lens set have negative focal power, the first lens set comprises at least one pair of opposite concave reflective surfaces, and at least two negative meniscus lenses are arranged between the opposite concave reflective surfaces. According to the catadioptric projection objective lens, the at least two negative meniscus lenses are arranged between the opposite concave reflective surfaces of the first lens set, field curvature and chromatic aberration generated during primary imaging can be effectively corrected by utilizing the negative focal power generated by the negative meniscus lenses to compensate the positive focal power generated by the concave reflective surfaces, the excellent constraint effect on a light incidence angle of the second lens set is realized, the largest caliber of the lenses is reduced, the aspheric quantity is reduced, and making and processing cost of optical systems and detection difficulty of optical elements are reduced.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a catadioptric projection objective lens based on a high numerical aperture. Background technique [0002] With the continuous improvement of the integration level of integrated circuit devices, the requirements for the resolution of the photolithography exposure system are also getting higher and higher. In order to improve the resolution of the system, two methods are usually used: one is to use a short-wavelength exposure light source, and the other is to increase the numerical aperture of the projection objective lens. [0003] However, when the wavelength of the light source is shortened and the numerical aperture of the projection objective lens is increased, the following problems will also appear: First, as the wavelength of the light source decreases, the requirements for optical materials are also getting higher and higher, and the stress birefringen...

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Problems solved by technology

[0003] However, when the wavelength of the light source is shortened and the numerical aperture of the projection objective lens is increased, the following problems will also appear: First, as the wavelength of the light source decreases, the requirements for optical materials are also getting higher and higher, and the stress birefringence, There are strict requirements on transmittance, light absorption coefficient, and chemical stability, which limit the choice of optical materials, and the Abbe numbers between optical materials are similar, which is not conducive to the correction of chromatic aberration in the optical system; the second is to better To correct image quality such as chromatic aberration and field curvature of the optical system, the aperture of the lens must increase with the increase of the numerical aperture, which not only increases the difficulty of optical manufacturing and inspection, but also greatly increases the cost of use; the third is to use the traditional full Refractive optical systems are difficult to correct for preliminary aberrations

[0004] In view of the above problems, the prior art provides a catadioptric projection objective lens, such as figure 1 As shown, including the first lens group G1', the second lens group G2' and the third lens group G3', the square numerical aperture of the catadioptric projection object image is 1.03, although the first lens group G1' adopts a pair of Concave mirrors M1', M2', but adding a positive lens in the middle did not play a good role in correcting the intermediate image quality, resulting in the maximum aperture of the optical system reaching 294mm, and using 11 aspheric surfaces, the optical manufacturing cost Higher, and when the numerical aperture of the image side is greater than 1.03, the correction effect of the combination of a pair of mirrors and a positive lens of the first lens group G1' on the image quality is greatly reduced, which has a great impact on the resolution of the entire optical system

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