Catadioptric photoetching projection system and exposure device

Abstract

According to the refraction and reflection type photoetching projection system and the exposure device provided by the invention, through cooperation of the non-concentric reflector assembly and the symmetric lens group, the system can realize comprehensive correction of third-order astigmatism, coma aberration, spherical aberration and chromatic aberration under the condition of a large numerical aperture, so that the wave aberration is kept within a diffraction limit, and the refraction and reflection type photoetching projection effect is improved. Therefore, the high-resolution imaging capability is maintained while the large exposure field is realized.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing, and more specifically to a catadioptric lithography projection system and exposure apparatus.

[0002] Background Technology In the field of photolithography projection technology, the resolution of the optical system is the core indicator determining the precision of the photolithography process, which follows the classic resolution formula in the field of photolithography: CD = In this system, CD is the smallest resolvable feature size of the optical system, λ is the system exposure wavelength, k represents the process factor which is determined by the level of photolithography process, and usually k takes a value of 0.6-0.8. NA represents the numerical aperture of the optical system, which is a key parameter reflecting the system's light-gathering capability.

[0003] Numerical aperture is usually calculated using NA = nsinθ, where n represents the refractive index of the medium in front of the objective lens and θ is the divergence angle of the optical system. As can be seen from the above formula, to achieve high resolution of the optical system, given a fixed exposure wavelength λ and process factor k, the numerical aperture NA of the system must be increased. Under air medium conditions, the core way to increase the numerical aperture is to increase the divergence angle θ of the optical system. To achieve high resolution, θ must be at least greater than 8.2°, i.e., numerical aperture NA > 0.142.

[0004] With the rapid development of the semiconductor industry and the continuous increase in wafer size, lithography equipment with a large exposure field of view can effectively improve wafer processing efficiency and occupy a significant advantage in the market. Therefore, the combination of large exposure field of view and high resolution has become an important design direction for lithography projection optical systems.

[0005] In the prior art, Japanese Patent JP7357488 discloses an optical lens with a large exposure field of view designed using an Offner optical structure for constructing an arc scanning projection exposure device, but its numerical aperture is only 0.105, making it difficult to achieve high-precision feature size photolithography imaging.

[0006] Therefore, how to overcome the shortcomings of the existing technology is the subject of this invention. Summary of the Invention

[0007] The purpose of this invention is to provide a catadioptric lithography projection system and exposure apparatus to solve the above-mentioned problems.

[0008] To achieve the above objectives, a first aspect of this application provides a catadioptric lithography projection system, including a first lens group, a mirror assembly, and a second lens group. The first lens group is located near the object plane, and the second lens group is located near the image plane. The mirror assembly is situated between the first and second lens groups. The mirror assembly includes a concave mirror and a convex mirror, the centers of curvature of which are not at the same point, but the straight line in which they lie constitutes the system optical axis. The first and second lens groups are symmetrical about the system optical axis.

[0009] Both the concave and convex reflectors are spherical reflectors with their reflecting surfaces facing each other. The system aperture is located on the convex reflector, and the radius of curvature of the concave reflector is R. 凹 The radius of curvature of the convex mirror is R. 凸 The two satisfy the following formula:

[0010]

[0011] ,

[0012] Where h is the maximum field of view height of the system; β is the edge ray angle of the system, β∈[8.2°, 10.5°]; c is the concentricity factor, and c∈[-0.0445, -0.0376].

[0013] The mirror assembly produces positive third-order astigmatism, while the first lens group and the second lens group produce negative third-order astigmatism of the same order of magnitude.

[0014] Light rays are incident on the object plane, pass through the first lens group, and then are reflected in sequence by the concave mirror for the first time, the convex mirror for the second time, and the concave mirror for the third time before passing through the second lens group to form an image on the image plane.

[0015] In the above scheme, the lens group is symmetrical along the optical axis and the aperture is located at the center of the structure, forming a double telecentric optical system. Therefore, there are no asymmetric aberrations such as coma or distortion in the system. The astigmatism of the system is effectively corrected by canceling the third-order astigmatism of the mirror assembly and the lens group. The non-concentric mirror structure not only ensures the numerical aperture improvement requirement, but also reduces the difficulty of aberration correction, ensuring that the system has high-resolution imaging capabilities.

[0016] In a further technical solution, both the first lens group and the second lens group adopt a typical positive-negative-positive three-element aberration correction structure, which has the optical characteristics of a long back focal length and low convergence. The first lens group sequentially includes a first meniscus lens, a second meniscus lens, and a third meniscus lens; the second lens group sequentially includes a fourth meniscus lens, a fifth meniscus lens, and a sixth meniscus lens; the fourth, fifth, and sixth meniscus lenses are symmetrical about the system optical axis with respect to the third, second, and first meniscus lenses, respectively.

[0017] The absolute optical power of each lens in the first and second lens groups is ≤0.001mm. -1 The first and sixth meniscus lenses have positive optical power, the second and fifth meniscus lenses have negative optical power, and the third and fourth meniscus lenses have positive optical power.

[0018] In the above scheme, by setting multiple lenses with low optical power, the system's aberration correction flexibility is increased, allowing aberrations to be dispersed and distributed across multiple lenses for correction. Since the optical power of each lens is very small, the refraction angle of light on each optical surface is gradual, and no single surface introduces drastic angular abrupt changes, thus effectively suppressing the generation of fundamental aberrations such as spherical aberration, coma, and astigmatism. Simultaneously, the low optical power design disperses chromatic aberration across multiple refractive surfaces, preventing a single lens from bearing excessive chromatic aberration. Combined with low-dispersion materials, this significantly suppresses overall chromatic aberration, enabling the system to maintain near-diffraction-limited high imaging quality even under large numerical aperture and large field of view conditions.

[0019] In a further design, the absolute value of the optical power of the first and sixth meniscus lenses ranges from 0.000032 mm. -1 ~ 0.000055 mm -1 The absolute values ​​of the optical power of the second and fifth meniscus lenses range from 0.00065 mm. -1 ~0.00068 mm -1 The absolute values ​​of the optical power of the third and fourth meniscus lenses range from 0.00055 mm. -1 ~0.00062 mm -1 The absolute optical power of the first and sixth meniscus lenses is extremely small, almost zero, while the absolute optical power of the second and fifth meniscus lenses is slightly greater than that of the third and fourth meniscus lenses. Therefore, the overall third-order astigmatism of the first and second lens groups remains negative, thus canceling out the positive third-order astigmatism of the mirror group. Furthermore, the second meniscus lens, with its negative optical power, can redistribute the ray height, significantly improving the degrees of freedom for correcting coma and astigmatism without increasing the system's numerical aperture, thereby expanding the system's usable field of view.

[0020] In a further technical solution, each lens in the first lens group and the second lens group adopts an Abbe number ν. _d Made of low dispersion material with a dispersion of ≥60.

[0021] In the above scheme, by using low-dispersion optical materials, chromatic aberration caused by the difference in refractive index of light of different wavelengths can be effectively suppressed, avoiding the resolution reduction caused by the imaging shift of light of different bands; at the same time, by combining a three-element low-power meniscus structure, the chromatic aberration of the system is evenly distributed to each optical surface of the three lenses, rather than concentrated in a single lens, minimizing the impact of chromatic aberration on imaging quality and ensuring that the system can still maintain high resolution under large numerical aperture and large field of view conditions.

[0022] In a further technical solution, the refractive index of the first and sixth meniscus lenses is 1.496~1.504; the refractive index of the second and fifth meniscus lenses is 1.526~1.536; and the refractive index of the third and fourth meniscus lenses is 1.467~1.475.

[0023] In the above scheme, by combining a reasonable gradient of different refractive indices with a low-light power design and low dispersion characteristics, light can be smoothly deflected on the surface of each lens, avoiding a surge in aberrations caused by abrupt changes in the refractive index of a single lens.

[0024] A further technical solution also includes a first plane mirror and a second plane mirror, which are respectively disposed between the first lens group and the mirror group, and between the second lens group and the mirror group, to change the direction of light propagation so that the light can adapt to the reflection path of the mirror assembly.

[0025] In the above scheme, by setting a first plane mirror and a second plane mirror, the light can be adapted to the reflection path of the mirror assembly, shortening the overall volume of the system, folding the optical system, separating the object plane and the image plane, and avoiding the two from overlapping and causing interference between the mask and the wafer spatial position.

[0026] Further technical solutions also include a first parallel plate and a second parallel plate, which are respectively placed between the object plane and the first lens group and between the image plane and the second lens group, for dust prevention and protection of the optical system.

[0027] According to a second aspect of this application, an exposure apparatus is provided, including a mask and a substrate, and further including a catadioptric lithography projection system as described in the first aspect, wherein a pattern of the mask is projected onto the substrate via the catadioptric lithography projection system.

[0028] The catadioptric photolithography projection system and exposure apparatus provided in this application have the following technical advantages:

[0029] This system employs a catadioptric structure combining a symmetrical lens group and a non-concentric double-spherical mirror assembly. The positive third-order astigmatism generated by the mirror assembly cancels out the negative third-order astigmatism generated by the lens group, thus resolving the astigmatism problem caused by the increased numerical aperture and exposure field of view. Furthermore, multiple low-power, low-dispersion lenses are used to correct chromatic aberration and spherical aberration. Without using complex aspherical surfaces or increasing the number of reflections, this system achieves high numerical aperture and wide field-of-view multi-band exposure imaging, significantly improving the resolution of lithographic imaging. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the catadioptric projection system provided in an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the exposure field of the catadioptric lithography projection system provided in an embodiment of the present invention;

[0032] Figure 3 The defocused MTF curve of the catadioptric lithography projection system provided in Embodiment 1 of the present invention;

[0033] Figure 4 This is a field curvature curve diagram of the catadioptric lithography projection system provided in Embodiment 1 of the present invention;

[0034] Figure 5 This is a distortion curve diagram of the catadioptric projection system provided in Embodiment 1 of the present invention;

[0035] Figure 6 This is a wavefront aberration diagram of the catadioptric projection system provided in Embodiment 1 of the present invention.

[0036] Figure 7 The defocused MTF curve of the catadioptric lithography projection system provided in Embodiment 2 of the present invention;

[0037] Figure 8 This is a field curvature diagram of the catadioptric lithography projection system provided in Embodiment 2 of the present invention;

[0038] Figure 9 This is a distortion curve diagram of the catadioptric lithography projection system provided in Embodiment 2 of the present invention;

[0039] Figure 10 This is a wavefront aberration diagram of the catadioptric projection system provided in Embodiment 2 of the present invention. Detailed Implementation

[0040] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0041] The terms "first," "second," etc., used in this article do not specifically refer to order or sequence, nor are they intended to limit this case; they are merely used to distinguish components or operations described using the same technical terms.

[0042] The terms "connection" or "positioning" as used in this article can refer to two or more components or devices making direct physical contact with each other, or making indirect physical contact with each other, or to two or more components or devices operating or moving with each other.

[0043] The terms “include,” “including,” and “have” used in this article are all open-ended, meaning they include but are not limited to.

[0044] The terms “front,” “back,” “up,” “down,” “left,” and “right” used in this article are directional terms. In this case, they are only used to describe the positional relationship between the structures and are not intended to limit the specific direction of the protection scheme or its actual implementation.

[0045] See Figure 1 This embodiment provides a catadioptric lithography projection system, which consists of the following components along the light propagation direction from the object plane S1 to the image plane S2: a first parallel plate T1, a first lens group (including a first meniscus lens L1, a second meniscus lens L2 and a third meniscus lens L3), a first planar mirror P1, a mirror assembly (including a concave mirror M1 and a convex mirror M2), a second planar mirror P2, a second lens group (including a fourth meniscus lens L4, a fifth meniscus lens L5 and a sixth meniscus lens L6), and a second parallel plate T2.

[0046] The concave mirror M1 and the convex mirror M2 are positioned opposite each other, and their centers of curvature do not coincide, but the straight line they lie on is the optical axis of the system. The concave mirror M1 and the convex mirror M2 form a non-concentric structure, and the system aperture is located on the convex mirror.

[0047] The first parallel plate T1, the first meniscus lens L1, the second meniscus lens L2, and the third meniscus lens L3 are positioned on the left side of the optical axis; the fourth meniscus lens L4, the fifth meniscus lens L5, the sixth meniscus lens L6, and the second parallel plate T2 are positioned on the right side of the optical axis. The first plane mirror P1 and the second plane mirror P2 are positioned at a 45° angle to the optical axis on opposite sides. The first parallel plate T1 and the second parallel plate T2, the first meniscus lens L1 and the sixth meniscus lens L6, the second meniscus lens L2 and the fifth meniscus lens L5, the third meniscus lens L3 and the fourth meniscus lens L4, and the first plane mirror P1 and the second plane mirror P2 all have the same radius of curvature and center thickness, and the system has a centrally symmetrical structure along the optical axis.

[0048] After receiving illumination, a beam of light is emitted from any point A on the mask surface S1, with its principal ray perpendicular to the optical axis. The principal ray emitted from point A passes through the first parallel plate T1, the first meniscus lens L1, the second meniscus lens L2, and the third meniscus lens L3, and is reflected by the first plane mirror P1. At this time, the principal ray is incident on the left half of the concave mirror M1 in a direction parallel to the optical axis. M1 has positive optical power and the system aperture is set on the convex mirror, so the principal ray converges and is reflected to the intersection of the convex mirror M2 and the optical axis (i.e., the center of the system aperture). Since the convex mirror has negative optical power, the principal ray diverges and is reflected to the right half of M1. Subsequently, the principal ray still exits in a direction parallel to the optical axis to the second mirror P2. After being reflected and redirected by P2, the light passes through the fourth meniscus lens L4, the fifth meniscus lens L5, the sixth meniscus lens L6, and the second parallel plate T2, converging onto the wafer image surface S2, forming point A' with a magnification of -1.

[0049] Since the meniscus lens in the second lens group has the same radius of curvature and central thickness as the first lens group, the two lens groups are symmetrical about the optical axis. Both the concave and convex mirrors are positioned perpendicular to the optical axis with their reflecting surfaces facing each other. The system aperture is located on the convex mirror, and light emitted from the object is reflected twice on the same concave mirror. This constitutes a telecentric optical system, thus eliminating asymmetric aberrations such as coma and distortion.

[0050] Taking the first lens group as an example, it adopts a positive-negative-positive three-element aberration correction structure, which has the optical characteristics of a long back focal length and low convergence. The first meniscus lens has positive optical power, and its optical power is extremely small, almost zero, with the absolute value of the optical power ranging from 0.000032mm. -1 ~ 0.000055 mm -1 The second meniscus lens has negative optical power; its optical power is very small, with an absolute value ranging from 0.00065 mm. -1 ~0.00068 mm -1The third meniscus lens has positive optical power, with an absolute value slightly smaller than that of the second meniscus lens, ranging from 0.00055 mm. -1 ~0.00062 mm -1 The second lens group is symmetrical to the first lens group. Both meniscus lenses use low-dispersion optical materials, forming a low-chromatic-aberration optical system. The chromatic aberration is distributed across multiple weak-light focal planes, increasing the system's aberration correction flexibility. This allows aberrations to be dispersed and distributed across multiple lenses for correction, and minimizes chromatic aberration problems to the greatest extent possible.

[0051] The exposure bands of this system are the i-line band, h-line band, and g-line band. Therefore, the glass material of the lenses in the system must be i-line glass or synthetic quartz that is resistant to ultraviolet radiation. Considering material stability and size limitations, in this embodiment, the first meniscus lens uses i-line glass with an Abbe number of 70.36 and a refractive index of 1.504 in the i-line; the second meniscus lens uses i-line glass with an Abbe number of 64.24 and a refractive index of 1.536 in the i-line; and the third meniscus lens uses synthetic quartz glass with an Abbe number of 67.8 and a refractive index of 1.475 in the i-line.

[0052] The first meniscus lens is used to initially deflect the incident light rays. Because its dispersion coefficient and optical power are both relatively small, the aberration changes it introduces are relatively gradual, primarily compensating for the aberrations introduced by the negative optical power of the second meniscus lens. The second meniscus lens, by redistributing the ray height, significantly improves the degrees of freedom for correcting coma and astigmatism without increasing the system's numerical aperture, thereby expanding the system's usable field of view. The third meniscus lens, made of low-refractive-index synthetic quartz glass, is used to correct spherical aberration caused by high ray positions under large numerical aperture conditions.

[0053] In addition, both the first and second lens groups introduce negative third-order astigmatism, while the combination of the concave and convex mirrors introduces positive third-order astigmatism. When the above optical elements are combined to form an optical system, the third-order astigmatism can cancel each other out and be corrected.

[0054] Both the concave and convex mirrors are spherical mirrors, with their reflecting surfaces positioned opposite each other. The concave mirror has positive optical power, and the convex mirror has negative optical power. The radii of curvature of the concave and convex mirrors satisfy the following relationship:

[0055]

[0056] ,

[0057] Where h is the maximum field of view height of the system, which is a fixed value preset according to the system requirements. In this embodiment, the maximum field of view height h is 135mm; β is the edge ray angle of the system, which refers to the maximum angle of light allowed by the optical system to meet numerical aperture matching and aberration correction. This angle is greater than or equal to the divergence angle of the optical system. By controlling the value of β, a large numerical aperture design can be achieved; c is the concentricity factor, which is used to describe the degree to which the mirror assembly deviates from the ideal concentric structure. When c≠0, it is considered non-concentric.

[0058] When c=0, the formula degenerates into the classical relation for an ideal concentric double-mirror structure:

[0059]

[0060] Classical concentric structures, limited by symmetry, struggle to correct off-axis aberrations at large numerical apertures, typically operating only at apertures of F / 4 or smaller. Non-concentric structures, on the other hand, can effectively balance higher-order aberrations at large numerical apertures.

[0061] Therefore, this application proposes a non-concentric mirror structure. By controlling the range of the concentricity factor c and the edge ray angle β, the radii of curvature of the concave and convex mirrors are designed. Through the cooperation of the non-concentric mirror assembly and the symmetrical lens group, the system can comprehensively correct astigmatism, coma, spherical aberration, and chromatic aberration under a large numerical aperture, while keeping wavefront aberration within the diffraction limit, achieving a balance between a large field of view and high resolution. To achieve a large field of view and high resolution, the divergence angle θ must be at least greater than 8.2°, i.e., the numerical aperture NA > 0.142, and correspondingly, the edge ray angle β must also be greater than 8.2°.

[0062] To maintain non-concentricity without generating excessive aberrations, the edge ray angle β of the system is set to [8.2°, 10.5°]. If β is too small, it will lead to mismatch of numerical aperture and overlapping of rays; if the value is too large, it will make aberration correction difficult and increase the system size, causing manufacturing difficulties. Since there is a lens group in the system, β is set to 10.2° in this embodiment to leave sufficient margin for lens optimization.

[0063] The concentricity factor c∈[-0.0445,-0.0376] allows the mirror assembly to be in a moderately non-concentric state within this range. This provides sufficient degrees of freedom for aberration adjustment to achieve aberration cancellation with the lens group, while avoiding the introduction of difficult-to-correct higher-order aberrations due to excessive deviation from the concentric structure. This ensures that the system still has excellent imaging quality under conditions of large field of view and large numerical aperture.

[0064] Substituting the values ​​of the system's maximum field of view height h = 135 mm, the edge ray angle β = 10.2°, and the concentricity factor c into the formula:

[0065]

[0066] Calculated , By inputting the calculation results into the simulation software, optimizing the curvature radius of each lens element and reflective element, as well as the distance between each optical element, the optimal solution can be obtained, enabling the system to meet the requirements of large field of view and high resolution lithography.

[0067] Example 1:

[0068] In this embodiment, It is 370mm. The value is 760mm, and the values ​​for each face are shown in the table below:

[0069] Face number radius of curvature thickness Object Infinity 20.00 1 Infinity 2.00 2 Infinity 34.18 3 585.00 35.88 4 609.50 87.27 5 -244.94 34.36 6 -367.00 1.00 7 -526.50 39.43 8 -322.00 527.66 9 -760.00 -372.30 STOP -370.00 372.30 11 -760.00 -527.66 12 -322.00 -39.43 13 -526.50 -1.00 14 -367.00 -34.36 15 -244.94 -87.27 16 609.50 -35.88 17 585.00 -34.18 18 Infinity -2.00 19 Infinity -20.00 Image Infinity

[0070] Among them, surfaces 1, 2, 18, and 19 correspond to the first and second parallel plates. Surfaces 3 and 4 correspond to the first meniscus lens, surfaces 5 and 6 correspond to the second meniscus lens, and surfaces 7 and 8 correspond to the third meniscus lens. Surfaces 9 and 11 correspond to the concave mirror, and STOP corresponds to the convex mirror. Surfaces 12 and 13 correspond to the fourth meniscus lens, surfaces 14 and 15 correspond to the fifth meniscus lens, and surfaces 16 and 17 correspond to the sixth meniscus lens.

[0071] Upon verification, the optical power of the first and sixth meniscus lenses is 0.000034, which is approximately 0.000032mm. -1 ~ 0.000055mm -1 The value range is [missing information]. The optical power of the second and fifth crescent lenses is 0.000679, which falls within the range of 0.00065 mm. -1 ~0.00068 mm -1 Within the range of values, the optical power of the third and fourth meniscus lenses is 0.000603, which is within the range of 0.00055 mm. -1 ~0.00062 mm -1 The range of values.

[0072] In this invention, the first and second parallel plates are placed on the object side and image side, respectively, mainly for dust prevention and to prevent chemical substances generated during exposure from contaminating the optical system. The material can be synthetic quartz. The first and second plane mirrors are used to fold the optical system, separating the object plane and the image plane to prevent them from overlapping and causing interference between the mask and the wafer's spatial position.

[0073] Figure 2 This is a schematic diagram of the effective exposure field of view of the photolithography projection system provided in this embodiment. Figure 2As shown in the figure, the white area represents the system's effective exposure field of view, which is an arc-shaped region with an arc width of approximately 10 mm, a field of view range of approximately -65.5°C to 65.5°C, and an arc length of approximately 131 mm. The uniform grayscale within the white area indicates a uniform distribution of light energy throughout the entire effective exposure field of view. This arc-shaped field of view design significantly improves wafer processing efficiency while ensuring consistent exposure dose across the entire field of view, meeting the lithography requirements of large-size wafers.

[0074] Figure 3 This is the modulation transfer function (MTF) curve of the photolithography projection system provided in this embodiment. The horizontal axis represents spatial frequency (unit: cycles / mm), indicating the fineness of the imaging detail; the vertical axis represents the MTF value, representing the system's ability to transfer contrast at that frequency, with values ​​closer to 1 indicating better image quality. Figure 3 As shown, the MTF curves in the meridional and sagittal directions of each field of view closely match the diffraction-limited curves. Even at high spatial frequencies (such as above 333 cycles / mm), the MTF values ​​of each field of view remain at a high level, indicating that the system has excellent resolution of fine features and meets the requirements of high-resolution lithography.

[0075] Figure 4 The field curves of the photolithography projection system provided in this embodiment are used to evaluate the image plane curvature of the system within the effective exposure field of view. In the left-hand graph, the horizontal axis represents the field curvature value (unit: μm), and the vertical axis represents the field position (unit: mm). The graph includes field curvature curves in both the tangential and sagittal directions. Within the effective exposure field of view, both curves are close to the vertical axis. The difference between the tangential and sagittal curves represents the average astigmatism of the system, indicating that the average astigmatism of the system is <4 μm.

[0076] Figure 5 The horizontal axis represents the distortion value (in %), and the vertical axis represents the field of view position (in mm). Because this system adopts a centrally symmetric structure, the distortion curves of each field of view coincide with the vertical axis, and the distortion value is close to 0.000%, with no obvious pincushion or barrel distortion, thus ensuring the geometric accuracy of the imaging.

[0077] Figure 6This is an RMS wavefront aberration curve of the photolithography projection system of the present invention, used to evaluate the wavefront error of the system within the effective exposure field of view. The horizontal axis represents the image field height of the optical system in the positive Y-axis direction (unit: mm), and the vertical axis represents the RMS wavefront aberration (unit: λ, where λ is the operating wavelength). The figure includes the measured wavefront aberration curves and diffraction-limited reference lines for each field of view. According to the Marechal criterion, when the wavefront error of the optical system does not exceed 1 / 14λ, the system can be considered diffraction-limited. As shown in the figure, the horizontal line represents the ideal wavefront aberration RMS < 0.07λ. The effective exposure field of view of the present invention is 125-135 mm, below the horizontal line, indicating that the design of the present invention is within the diffraction limit.

[0078] Example 2

[0079] In this embodiment, the radius of curvature of the convex reflector is taken as the maximum value, that is... =372, the optimized system result is as follows:

[0080] Face number radius of curvature thickness Object Infinity 20.00 1 Infinity 2.00 2 Infinity 32.2781 3 617.13 36.81 4 648.59 91.37 5 -244.96 32.46 6 -366.81 1.00 7 -522.78 37.45 8 -317.83 526.26 9 -760.00 -372.30 STOP -372 372.30 11 -760.00 -526.26 12 -317.83- -37.45 13 -522.78 -1.00 14 -366.81 -32.46 15 -244.96 -91.37 16 648.59 -36.81 17 617.13 -32.2781 18 Infinity -2.00 19 Infinity -20.00 Image Infinity

[0081] Upon verification, the optical power of the first and sixth meniscus lenses is 0.000039, which is approximately 0.000032mm. -1 ~ 0.000055mm -1 The value range is [missing information]. The optical power of the second and fifth crescent lenses is 0.000678, which falls within the range of 0.00065 mm. -1 ~0.00068 mm -1 Within the range of values, the optical power of the third and fourth meniscus lenses is 0.000617, which is within the range of 0.00055 mm. -1 ~0.00062 mm -1 The range of values.

[0082] Figure 7 This is the defocus MTF curve of the catadioptric lithography projection system provided in this embodiment. Figure 8 This is a field curvature diagram of the catadioptric lithography projection system provided in this embodiment. Figure 9 This is a distortion curve diagram of the catadioptric lithography projection system provided in this embodiment. Figure 10 This is a wavefront aberration diagram of the catadioptric lithography projection system provided in this embodiment. It can be seen that the optimized system in this embodiment has essentially the same imaging quality as the system in Embodiment 1.

[0083] Combining Embodiments 1 and 2, the system provided in this application can achieve arc-shaped lithography projection with a magnification of -1x (10mm arc width, 131mm arc length), adapting to multi-band exposure requirements of i-line, h-line, and g-line. Through a large numerical aperture design, the lithography resolution is significantly improved. Simultaneously, the system maintains excellent imaging quality across the entire field of view, effectively solving the problems of insufficient resolution and difficulty in aberration correction in traditional large-field-of-view lithography systems. It can meet the dual requirements of high resolution and a large exposure field of view for advanced semiconductor lithography processes.

[0084] It should be noted that the above embodiments are mainly described using a single-piece concave mirror as an example, but the scope of protection of this invention is not limited thereto. Under the premise of satisfying -1x magnification projection, optical path symmetry, and aberration correction, a structure in which the concave mirror is divided into two independent reflecting surfaces along the optical path and supported separately also falls within the scope of protection of this invention.

[0085] This application also provides an exposure apparatus, including a photomask, a substrate, and the aforementioned catadioptric lithography projection system. The circuit pattern on the photomask is clearly imaged onto the substrate surface by the catadioptric lithography projection system at a magnification of -1x, achieving high-precision, wide-field-of-view lithography exposure.

[0086] In summary, this application increases the degree of freedom in aberration adjustment by combining a non-concentric mirror assembly with a symmetrical lens group composed of multiple lenses. It can achieve comprehensive correction of third-order astigmatism, coma, spherical aberration and chromatic aberration under large numerical aperture conditions, keeping wave aberration within the diffraction limit, thereby maintaining high-resolution imaging capability while achieving a large exposure field of view.

[0087] This application uses the curvature radius relationship to precisely constrain the mirror assembly, ensuring the self-consistency of the optical path of the optical system and avoiding high-order aberration problems caused by excessive non-concentricity. Compared with existing large field-of-view lithography systems, this system achieves a large exposure field of view while having a simpler overall structure and stronger engineering feasibility, and can simultaneously meet the lithography application requirements of large numerical aperture, large exposure field of view and high resolution.

[0088] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A catadioptric photolithography projection system, characterized in that, The system includes a first lens group, a mirror assembly, and a second lens group. The first lens group is closer to the object plane, and the second lens group is closer to the image plane. The mirror assembly is located between the first lens group and the second lens group. The mirror assembly includes a concave mirror and a convex mirror. The centers of curvature of the two mirrors are not on the same line, but the straight line they lie on forms the optical axis of the system. The first lens group and the second lens group are symmetrical about the optical axis of the system. Both the concave and convex reflectors are spherical reflectors, and their reflecting surfaces are arranged opposite each other. The convex reflector integrates a system aperture, and the radius of curvature of the concave reflector is R. 凹 The radius of curvature of the convex mirror is R. 凸 The two satisfy the following formula: ， ， Where h is the maximum field of view height of the system; β is the edge ray angle of the system, β∈[8.2°,10.5°]; c is the concentricity factor, and c∈[-0.0445,-0.0376]; The mirror assembly produces positive third-order astigmatism, while the first lens group and the second lens group produce negative third-order astigmatism of the same order of magnitude. Light rays are incident on the object plane, pass through the first lens group, and then are reflected in sequence by the concave mirror for the first time, the convex mirror for the second time, and the concave mirror for the third time before passing through the second lens group to form an image on the image plane.

2. The catadioptric photolithography projection system according to claim 1, characterized in that: Both the first lens group and the second lens group adopt a positive, negative, and positive three-element aberration correction structure. The first lens group includes a first meniscus lens, a second meniscus lens, and a third meniscus lens in sequence. The second lens group includes a fourth meniscus lens, a fifth meniscus lens, and a sixth meniscus lens in sequence. The fourth meniscus lens, the fifth meniscus lens, and the sixth meniscus lens are symmetrical about the optical axis of the system with respect to the third meniscus lens, the second meniscus lens, and the first meniscus lens, respectively.

3. The catadioptric photolithography projection system according to claim 2, characterized in that: The first and sixth meniscus lenses have positive optical power, the second and fifth meniscus lenses have negative optical power, and the third and fourth meniscus lenses have positive optical power. The absolute value of the optical power of each lens in the first and second lens groups is ≤0.001mm. -1 .

4. The catadioptric photolithography projection system according to claim 3, characterized in that: The absolute value of the optical power of the first and sixth crescent lenses ranges from 0.000032 mm. -1 ~ 0.000055 mm -1 The absolute values ​​of the optical power of the second and fifth meniscus lenses range from 0.00065 mm. -1 ~0.00068 mm -1 The absolute values ​​of the optical power of the third and fourth meniscus lenses range from 0.00055 mm. -1 ~0.00062 mm -1 .

5. The catadioptric photolithography projection system according to claim 2, characterized in that: Each lens in the first and second lens groups uses an Abbe number ν. d Made of low dispersion material with a dispersion of ≥60.

6. The catadioptric photolithography projection system according to claim 2, characterized in that: The refractive indices of the first and sixth meniscus lenses are 1.496 to 1.504; the refractive indices of the second and fifth meniscus lenses are 1.526 to 1.536; and the refractive indices of the third and fourth meniscus lenses are 1.467 to 1.

475.

7. The catadioptric photolithography projection system according to claim 1, characterized in that: The system aperture is coaxially arranged with the convex reflector.

8. The catadioptric photolithography projection system according to claim 1, characterized in that: It also includes a first plane mirror and a second plane mirror, which are respectively disposed between the first lens group and the mirror group, and between the second lens group and the mirror group, to change the direction of light propagation so that the light can adapt to the reflection path of the mirror assembly.

9. The catadioptric photolithography projection system according to claim 1, characterized in that: It also includes a first parallel plate and a second parallel plate, which are placed between the object plane and the first lens group and between the image plane and the second lens group, respectively, for dust prevention and protection of the optical system.

10. An exposure apparatus comprising a mask and a substrate, further comprising a catadioptric lithography projection system as described in claims 1 to 9, wherein a pattern of the mask is projected onto the substrate via the catadioptric lithography projection system.

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