A reflective lithography lens

Abstract

The present invention relates to a reflective lithography lens, comprising a first lens and a first reflector, arranged sequentially along a first optical axis; a second reflector, arranged sequentially along a second optical axis; an aperture, arranged concentrically with the second reflector; a second lens group; and a sixth lens. By constraining the distance between the object plane and the first lens and the distance between the aperture and the image plane, various optical aberrations are effectively balanced, enabling the lithography lens to achieve a larger field of view while also exhibiting excellent imaging performance, thereby resolving the problem of a limited field of view in existing lithography lenses. Furthermore, the lithography lens of the present invention utilizes a reflective structure, causing light to pass through the second lens group twice, in both forward and reverse directions. This reduces the number of lens elements while ensuring the beam transmission distance, thereby effectively reducing the size of the lithography lens and lowering its cost and assembly difficulty.

Description

Technical Field

[0001] The present invention relates to the technical field of photolithography, and in particular to a reflective photolithography lens. Background Art

[0002] Optical exposure equipment, also known as photolithography machines, utilize the principle of optical projection imaging to transfer integrated circuit patterns from a mask onto a coated silicon wafer in a distributed, repetitive, or scanning manner, thereby fabricating semiconductor devices. The photolithography lens is a crucial imaging component in photolithography machines and is one of the primary factors influencing the line width and area of ​​the photolithography.

[0003] As the scope of photolithography applications continues to expand, the requirements for photolithography products are becoming increasingly stringent, and the lithography area is also increasing. However, the current lens-type photolithography lens has a small field of view, making it impossible to directly process large-area photolithography patterns. Multiple small-area photolithography passes are required, followed by moving and splicing to form a large-area photolithography pattern. This splicing process introduces stitching errors, which can seriously affect the accuracy of the photolithography pattern. Furthermore, current transmissive photolithography lenses generally have more than ten lenses, resulting in large size and high cost. Summary of the Invention

[0004] The present invention aims to provide a reflective lithography lens that has excellent imaging performance while achieving a large field of view.

[0005] To achieve the above objectives, the present invention provides a reflective lithography lens for use in the ultraviolet band, characterized in that it includes a first lens and a first reflector sequentially arranged along a first optical axis, a second reflector sequentially arranged along a second optical axis, an aperture concentrically arranged with the second reflector, a second lens group, and a sixth lens, wherein the first optical axis and the second optical axis are perpendicular to each other;

[0006] The first lens is disposed close to the object plane; the first reflector is located on a side of the first lens away from the object plane and is disposed between the second lens group and the sixth lens, the first reflector forms an angle of 45° with the first optical axis, and the second reflector is perpendicular to the second optical axis;

[0007] The light beam emitted from the object plane passes through the first lens, is reflected by the first reflector to the forward direction, passes through the second lens group, is reflected by the second reflector to the reverse direction, passes through the second lens group, and then passes through the sixth lens to converge onto the imaging surface; the photolithography lens satisfies the following relationship:

[0008] 0.02 <D1 / f<0.021

[0009] 0.15 <D2 / f<0.16

[0010] Where f is the total optical power of the lithography lens, D1 is the distance from the object plane to the first lens, and D2 is the distance from the aperture stop to the image plane.

[0011] As a further improvement of the present invention, the first lens has a positive optical power and satisfies the relationship: 0.41 < f1 / f < 0.43, where f1 is the focal length of the first lens; the sixth lens has a positive optical power and satisfies the relationship: 0.41 < f6 / f < 0.43, where f6 is the focal length of the sixth lens.

[0012] As a further improvement of the present invention, the first lens is a meniscus lens with its concave surface facing the object plane, and the sixth lens is a meniscus lens with its concave surface facing the image plane.

[0013] As a further improvement of the present invention, the first lens and the sixth lens are each half of the same integral spherical lens.

[0014] As a further improvement of the present invention, the second lens group includes a second lens, a third lens, a fourth lens, and a fifth lens arranged in sequence. The second lens is disposed on a side close to the first reflector, the fifth lens is disposed on a side close to the second reflector, the second lens, the third lens, and the fourth lens each have a positive optical power, and the fifth lens has a negative optical power.

[0015] The second lens group satisfies the relationships:

[0016] 0.1 < f2 / f < 0.12

[0017] 0.06 < f3 / f < 0.08

[0018] 0.08 < f4 / f < 0.1

[0019] -0.03 < f5 / f < -0.02

[0020] Where f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, and f5 is the focal length of the fifth lens.

[0021] As a further improvement of the present invention, the second lens is a biconvex lens, the third lens, the fourth lens, and the fifth lens are each meniscus lenses with their concave surfaces facing the aperture stop, and the distance between the side of the fifth lens close to the aperture stop and the aperture stop is greater than 120 mm.

[0022] As a further improvement of the present invention, the refractive index of the first lens ranges from 1.5 to 1.6, and the dispersion coefficient of the first lens ranges from 60 to 65. The ranges of the refractive index and the dispersion coefficient of the second lens, the third lens, the fourth lens and the sixth lens are the same as those of the first lens; the refractive index of the fifth lens ranges from 1.6 to 1.7, and the dispersion coefficient of the fifth lens ranges from 35 to 40.

[0023] As a further improvement of the present invention, the side of the first lens close to the object surface is set as the object surface side, and the side away from the object surface is set as the image surface side. The range of the curvature radius R1 of the object surface side of the first lens is 1176.96 mm < R1 < 1179.96 mm, and the range of the curvature radius R11 of the image surface side of the first lens is 783.45 mm < R11 < 786.45 mm;

[0024] As a further improvement of the present invention, the sides of the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens close to the aperture stop are set as the image surface side, and the sides away from the aperture stop are set as the object surface side, where:

[0025] The range of the curvature radius R2 of the object surface side of the second lens is 1129.95 mm < R2 < 1132.95 mm, and the range of the curvature radius R21 of the image surface side of the second lens is 1,277.54 mm < R21 < 1,280.54 mm;

[0026] The range of the curvature radius R3 of the object surface side of the third lens is 296.41 mm < R3 < 299.41 mm, and the range of the curvature radius R^31 of the image surface side of the third lens is 1,267.99 mm < R31 < 1,270.99 mm;

[0027] The range of the curvature radius R^4 of the object surface side of the fourth lens is 286.49 mm < R4 < 289.49 mm, and the range of the curvature radius R^41 of the image surface side of the fourth lens is 672.46 mm < R41 < 675.46 mm;

[0028] The range of the curvature radius R^5 of the object surface side of the fifth lens is 1,621.06 mm < R5 < 1,624.06 mm, and the range of the curvature radius R^51 of the image surface side of the fifth lens is 154.14 mm < R51 < 157.14 mm;

[0029] The value range of the radius of curvature R6 on the object side of the sixth lens is 1176.96 mm < R6 < 1179.96 mm, and the value range of the radius of curvature R61 on the image side of the sixth lens is 783.45 mm < R61 < 786.45 mm.

[0030] The first lens, the second lens, the third lens, the fourth lens and the sixth lens are all made of crown glass material, and the fifth lens is made of flint glass material.

[0031] As a further improvement of the present invention, the lithography lens is an equal magnification imaging lens, and the ultraviolet wavelength range applied by the lithography lens is 400 nm ≤ λ ≤ 410 nm.

[0032] Compared with the prior art, in the reflective lithography lens of the present invention, the light beam emitted from the object surface enters the first lens, and after passing through the first lens, it is reflected by the first mirror and enters the second lens group. The light beam after passing through the second lens group forward is reflected back to the second lens group by the second mirror, and the light beam after passing through the second lens group backward enters the sixth lens and is converged by the sixth lens to form an image surface. By restricting the distance from the object surface to the first lens and the distance from the aperture stop to the image surface, various optical aberrations can be better balanced, enabling the lithography lens to have excellent imaging performance while achieving a larger field of view, thus solving the problem of the small field of view of the existing lithography lens. In addition, the lithography lens of the present invention adopts a reflective structure, enabling the light beam to pass through the second lens group forward and backward twice, reducing the number of lenses by half while ensuring the light beam transmission distance, thereby effectively reducing the volume of the lithography lens, lowering the cost of the lithography lens, and reducing the assembly difficulty of the lithography lens. Description of the Drawings

[0033] Figure 1 is a schematic structural diagram of the lithography lens in a specific embodiment of the present application;

[0034] Figure 2 is a modulation transfer function diagram of the lithography lens in a specific embodiment of the present application;

[0035] Figure 3 is a spot diagram of the lithography lens in a specific embodiment of the present application;

[0036] Figure 4 is a distortion diagram of the lithography lens in a specific embodiment of the present application.

[0037] Reference Signs:

[0038] 1, first lens; 2, first mirror; 3, second mirror; 4, aperture stop; 5, second lens group; 51, second lens; 52, third lens; 53, fourth lens; 54, fifth lens; 6, sixth lens. Detailed Embodiments

[0039] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described below with reference to specific embodiments shown in the accompanying drawings.

[0040] A reflective lithography lens, used in the ultraviolet band, comprises a first lens 1 and a first reflector 2, arranged in sequence along a first optical axis; a second reflector 3, arranged in sequence along a second optical axis; an aperture 4, arranged concentrically with the second reflector 3; a second lens group 5; and a sixth lens 6. In the lithography lens, the direction of the main beam in the object plane field of view is the direction of the first optical axis, and the direction of the main beam in the image plane field of view is the direction of the second optical axis. The first optical axis direction is represented by y, and the second optical axis direction is represented by x. The first optical axis direction y and the second optical axis direction x are perpendicular to each other.

[0041] The first lens 1 is arranged close to the object plane; the first reflector 2 is located on the side of the first lens 1 away from the object plane, and is arranged between the second lens group 5 and the sixth lens 6. The first reflector 2 is at 45 degrees to the direction of the first optical axis, and the first reflector 2 is arranged between the second lens group 5 and the sixth lens 6. The second reflector 3 is perpendicular to the direction of the second optical axis, that is, the second reflector 3 is extended along the direction of the first optical axis.

[0042] The light beam emitted from the object plane passes through the first lens 1, is reflected by the first reflector 2, passes through the second lens group 5 in the forward direction, is reflected by the second reflector 3, passes through the second lens group 5 in the reverse direction, and then passes through the sixth lens 6 to converge onto the imaging surface.

[0043] The photolithography lens satisfies the following relationship:

[0044] 0.02 <D1 / f<0.021

[0045] 0.15 <D2 / f<0.16

[0046] Where f is the total focal length of the lithography lens, D1 is the distance from the object plane to the first lens, and D2 is the distance from the aperture to the image plane.

[0047] In the reflective lithography lens of the present invention, the light beam emitted from the object plane enters the first lens 1. After passing through the first lens 1, the propagation direction of the light beam is changed by the first mirror 2, so that the light beam enters the second lens group 5 in the forward direction. Then, it is reflected back to the second lens group 5 by the second mirror 3, and the light beam passes through the second lens group 5 in the reverse direction and then enters the sixth lens 6. The sixth lens 6 converges to form an image plane. By restricting the distance from the object plane to the first lens and the distance from the aperture to the image plane, various optical aberrations can be better balanced. When the lithography lens realizes a larger field of view, it has excellent imaging performance, thus solving the problem of the small field of view of the existing lithography lens. In addition, the lithography lens of the present invention adopts a reflective structure, which makes the light beam pass through the second lens group 5 twice in the forward and reverse directions. While ensuring the light beam transmission distance, the number of lenses is reduced by half, thereby effectively reducing the volume of the lithography lens, and reducing the cost and assembly difficulty of the lithography lens.

[0048] It can be understood that the forward and reverse directions referred to in the present invention mean that the directions of the light beam passing through the second lens group 5 twice are opposite. The specific settings of the forward and reverse directions and the settings of the lenses in the second lens group 5 can be adjusted according to the actual situation.

[0049] Specifically, the lithography lens is an equal-magnification imaging lens. The wavelength range value applied by the lithography lens is 400nm ≤ λ ≤ 410nm, and the maximum field of view of the object plane can reach 200mm × 100mm.

[0050] The first lens 1 has a positive optical power. The side of the first lens 1 close to the object plane is concave, and the side far from the object plane is convex. The first lens satisfies the relationship: 0.41 < f1 / f < 0.43, where f1 is the focal length of the first lens. The sixth lens 6 has a positive optical power. The side of the sixth lens 6 close to the image plane is concave, and the side far from the image plane is convex. The sixth lens 6 satisfies the relationship: 0.41 < f6 / f < 0.43, where f6 is the focal length of the sixth lens. By restricting the focal lengths of the first lens 1 and the sixth lens 6, the lithography lens can obtain excellent imaging quality.

[0051] In one embodiment, the first lens 1 is a meniscus lens with the concave surface facing the object plane, and the sixth lens 6 is a meniscus lens with the concave surface facing the image plane. In another embodiment, the first lens 1 and the sixth lens 6 are each half of the same complete spherical lens, as shown in Figure 1 the structural schematic diagram of the lithography lens. The first lens 1 and the sixth lens 6 are both half-spherical lenses. The first lens 1 and the sixth lens 6 can be spliced into a complete spherical lens, thereby reducing the volume of the first lens 1 and the sixth lens 6, being more conducive to the miniaturization of the lithography lens, and at the same time saving the cost of the lithography lens.

[0052] Both the first reflector 2 and the second reflector 3 are plane reflectors. The 45° angle between the first reflector 2 and the first optical axis can be understood as the minimum angle between the reflecting surface of the first reflector 2 and the first optical axis. In one embodiment, as Figure 1 shown in the schematic structural diagram of the lithography lens, the direction of the first optical axis is the vertical direction, and the direction of the second optical axis is the horizontal direction. Then, the first reflector 2 forms a 45° angle with the direction of the first optical axis. The light beam transmitted along the first optical axis is changed to be transmitted along the second optical axis through the first reflector 2, so that a relatively long distance is generated between the object plane and the image plane, leaving sufficient mechanical space. It can be understood that the first reflector 2 of the lithography lens in the present invention is not limited to Figure 1 the placement method in. In other embodiments, the first reflector 2 can be Figure 1 mirror - set with the first reflector 2 in, and the symmetry axis is the direction of the first optical axis.

[0053] The aperture stop 4 refers to an entity that restricts the light beam in an optical system. The aperture stop 4 can be the edge of a lens, a frame, or a specially - set perforated screen. In a specific embodiment, the aperture stop 4 is arranged on the second reflector 3, and the center of the aperture stop 4 coincides with the center of the second reflector 3.

[0054] The second lens group 5 includes a second lens 51, a third lens 52, a fourth lens 53, and a fifth lens 54 arranged in sequence. The second lens 51 is arranged on the side close to the first reflector 2, and the fifth lens 54 is arranged on the side close to the second reflector 3. The second lens 51, the third lens 52, and the fourth lens 53 all have positive optical powers, and the fifth lens 54 has negative optical power. The second lens 51 satisfies the relation: 0.1 < f2 / f < 0.12, the third lens 52 satisfies the relation: 0.06 < f3 / f < 0.08, the fourth lens 53 satisfies the relation: 0.08 < f4 / f < 0.1, and the fifth lens 54 satisfies the relation: - 0.03 < f5 / f < - 0.02, where f2 is the focal length of the second lens; f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, and f5 is the focal length of the fifth lens. When the focal lengths of each lens in the second lens group 5 of the lithography lens satisfy the above relations, the lithography lens can obtain excellent imaging quality.

[0055] In one embodiment, the second lens 51 is a biconvex lens, and the third lens 52, the fourth lens 53, and the fifth lens 54 are all meniscus lenses with their concave surfaces facing the aperture 4. Preferably, the distance between the side of the fifth lens close to the aperture and the aperture is greater than 120 mm. The forward passage through the second lens group 5 specifically means that the light beam passes through the second lens 51, the third lens 52, the fourth lens 53, and the fifth lens 54 in sequence; the reverse passage through the second lens group 5 specifically means that the light beam passes through the fifth lens 54, the fourth lens 53, the third lens 52, and the second lens 51 in sequence. The second lens group 5 adopts a combination of a biconvex lens and a meniscus lens. By configuring appropriate optical powers for each lens, after the light beam passes through the second lens group 5 twice in both forward and reverse directions, the desired transmission direction and transmission distance can be obtained, saving nearly half of the number of lenses, effectively reducing the volume of the lithography lens, and lowering the cost of the lithography lens.

[0056] The transmission path of the light beam is as Figure 1 shown by the straight line in the figure. The light beam emitted from the object surface exits along the first optical axis direction through the first lens 1, first changes the direction of the light beam through the first mirror 2, and then the light beam passes through the second lens 51, the third lens 52, the fourth lens 53, and the fifth lens 54 in sequence. The transmission direction of the light beam is adjusted by the second lens 51, the third lens 52, the fourth lens 53, and the fifth lens 54 in sequence, so that the light beam converges to the second mirror 3 and is reflected back to the second lens group 5 by the second mirror 3. At this time, the light beam passes through the fifth lens 54, the fourth lens 53, the third lens 52, and the second lens 51 in sequence, and the transmission direction of the light beam is adjusted by the fifth lens 54, the fourth lens 53, the third lens 52, and the second lens 51 in sequence, so that the light beam enters the sixth lens 6 and converges to the image surface by the sixth lens 6.

[0057] In the present invention, the value range of the focal length f1 of the first lens 1 is 4150 mm < f1 < 4200 mm, the value range of the focal length f2 of the second lens 51 is 1100 mm < f2 < 1150 mm, the value range of the focal length f3 of the third lens 52 is 700 mm < f3 < 750 mm, the value range of the focal length f4 of the fourth lens 53 is 850 mm < f4 < 900 mm, the value range of the focal length f5 of the fifth lens 54 is -300 mm < f5 < -250 mm, and the value range of the focal length f6 of the sixth lens 6 is 4150 mm < f6 < 4200 mm.

[0058] The value range of the refractive index of the first lens 1 is 1.5 - 1.6, and the value range of the dispersion coefficient of the first lens 1 is �0 - 65. The value ranges of the refractive index and the dispersion coefficient of the second lens 51, the third lens 52, the fourth lens 53, and the sixth lens 6 are the same as those of the first lens 1; the value range of the refractive index of the fifth lens 54 is 1.6 - 1.7, and the value range of the dispersion coefficient of the fifth lens 54 is 35 - 40.

[0059] Set the side of the first lens 1 close to the object surface as the object surface side, and the side of the first lens 1 away from the object surface as the image surface side. The value range of the curvature radius R1 of the object surface side of the first lens 1 is 1176.96 mm < R < 1179.96 mm, and the value range of the curvature radius R11 of the image surface side of the first lens 1 is 783.45 mm < R < 786.45 mm;

[0060] Set the sides of the second lens 51, the third lens 52, the fourth lens 53, the fifth lens 54 and the sixth lens 6 close to the aperture 4 as the image surface side, and the sides of the second lens 51, the third lens 52, the fourth lens 53, the fifth lens 54 and the sixth lens 6 away from the aperture 4 as the object surface side, where:

[0061] The value range of the curvature radius R2 of the object surface side of the second lens 51 is 1129.95 mm < R < 1132.95 mm, and the value range of the curvature radius R21 of the image surface side of the second lens 51 is 1277.54 mm < R < 1280.54 mm;

[0062] The value range of the curvature radius R3 of the object surface side of the third lens 52 is 296.41 mm < R < 299.41 mm, and the value range of the curvature radius R31 of the image surface side of the third lens 52 is 1267.99 mm < R < 1270.99 mm;

[0063] The value range of the curvature radius R4 of the object surface side of the fourth lens 53 is 286.49 mm < R < 289.49 mm, and the value range of the curvature radius R41 of the image surface side of the fourth lens 53 is 672.46 mm < R < 675.46 mm;

[0064] The value range of the curvature radius R5 of the object surface side of the fifth lens 54 is 1621.06 mm < R < 1624.06 mm, and the value range of the curvature radius R51 of the image surface side of the fifth lens 54 is 154.14 mm < R < 157.14 mm;

[0065] The value range of the curvature radius R6 of the object surface side of the sixth lens 6 is 1176.96 mm < R < 1179.96 mm, and the value range of the curvature radius R61 of the image surface side of the sixth lens 6 is 783.45 mm < R < 786.45 mm.

[0066] It can be understood that the radius range on the image side or object side of each lens is the value range of the absolute value of the actual radius. For example, the radius range on the object side of the first lens 1 is 1176.96 mm < |R| < 1179.96 mm, and the radius range on the image side of the first lens 1 is 783.45 mm < |R| < 786.45 mm. The radius ranges of other lenses are also the value ranges of the absolute values of their radii, which will not be elaborated here. In a specific embodiment, the radius values on both the object side and the image side of the first lens 1 are negative. The radius value of the convex surface of the object side or the image side of the second lens 51, the third lens 52, the fourth lens 53, the fifth lens 54, and the sixth lens 6 facing the direction close to the aperture is positive, and the radius value of the convex surface of the object side or the image side facing the direction close to the image plane is negative.

[0067] The reflective lithography lens will be described below through a specific embodiment.

[0068] The lithography lens of this embodiment includes a first lens 1 and a first mirror 2 arranged along the first optical axis direction, a second mirror 3 arranged along the second optical axis direction, an aperture 4 arranged on the second mirror 3 and coinciding with the center of the second mirror 3, a second lens 51, a third lens 52, a fourth lens 53, a fifth lens 54, and a sixth lens 6. Among them, the second lens 51, the third lens 52, the fourth lens 53, and the fifth lens 54 form a second lens group 5. The first lens 1 is a meniscus lens with the concave surface facing the object plane. The second lens 51 is a biconvex lens. The third lens 52, the fourth lens 53, and the fifth lens 54 are all meniscus lenses with the concave surfaces facing the aperture 4. The sixth lens 6 is a meniscus lens with the concave surface facing the image plane. The first lens 1, the second lens 51, the third lens 52, the fourth lens 53, and the sixth lens 6 all have positive optical powers, and the fifth lens 54 has a negative optical power. The first lens 1 and the sixth lens 6 are each half of the same complete spherical lens.

[0069] The lithography lens satisfies the relationships: 0.02 < D1 / f < 0.021 and 0.15 < D2 / f < 0.16, where f is the total optical power of the lithography lens, D1 is the distance from the object plane to the first lens 1, D2 is the distance from the aperture 4 to the image plane, and the distance between the side of the fifth lens 54 close to the aperture 4 and the aperture 4 is greater than 120 mm.

[0070] The wavelength range value applied by the lithography lens is 400 nm ≤ λ ≤ 410 nm.

[0071] The specific parameters of each lens are as follows in the table:

[0072]

[0073] In the table, R represents the radius of curvature of each optical element, TH represents the center thickness of each optical element, Nd represents the refractive index of each optical element, and Vd represents the Abbe constant of each optical element. The first, second, third, fourth, and sixth lenses in the table are all made of crown glass (H-K9LGT_CDGM), while the fifth lens is made of flint glass (F4GTI_CDGM). Using different glass materials within the lithography lens ensures that each lens meets the required optical imaging quality.

[0074] After configuring according to the above table, perform optical testing and obtain Figure 2-Figure 4 The test results.

[0075] Figure 2 The modulation transfer function (MTF) diagram of the lithography lens is shown in Figure 2. Figure 2 It can be seen that the MTF value of the lithography lens at each frequency is close to the diffraction limit, and the lithography lens can achieve good imaging quality.

[0076] Figure 3 is the spot diagram of the photolithography lens, from Figure 3 It can be seen that the root mean square radius of the lithography lens in each field of view is within the radius of the Airy disk, and the various aberrations of the lithography lens are well balanced.

[0077] Figure 4 is the distortion diagram of the lithography lens, from Figure 4 It can be seen that the distortion correction of the lithography lens is 1*10 -5 Within the mm range, the distortion value of the lithography lens is small and the imaging quality is high.

[0078] The effective field of view of the photolithography lens object plane can reach 218mm*108mm, with a numerical aperture of 0.046. The photolithography lens has equal magnification imaging and inverted imaging.

[0079] The lithography lens of the present invention has a wide field of view, enabling direct large-area lithography pattern processing and avoiding the problem of stitching errors affecting pattern accuracy. Furthermore, by combining positive and negative lenses and configuring appropriate optical parameters, the lithography lens can achieve high imaging quality. Furthermore, the lithography lens of the present invention utilizes a reflective structure, allowing the light beam to pass through the second lens group twice, in both forward and reverse directions. This reduces the number of lenses while ensuring the beam transmission distance, thereby effectively reducing the size and cost of the lithography lens.

[0080] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A reflective lithography lens for use in the ultraviolet band, characterized in that: The lens comprises a first lens and a first reflector sequentially arranged along a first optical axis, a second reflector sequentially arranged along a second optical axis, an aperture concentrically arranged with the second reflector, a second lens group, and a sixth lens, wherein the first optical axis direction is perpendicular to the second optical axis direction; The first lens is disposed close to the object plane; the first reflector is located on a side of the first lens away from the object plane and is disposed between the second lens group and the sixth lens, the first reflector forms an angle of 45° with the first optical axis, and the second reflector is perpendicular to the second optical axis; The light beam emitted from the object plane passes through the first lens, is reflected by the first reflector to the forward direction, passes through the second lens group, is reflected by the second reflector to the reverse direction, passes through the second lens group, and then passes through the sixth lens to converge onto the image plane; The photolithography lens satisfies the following relationship: 0.02 <D1 / f<0.021 0.15 <D2 / f<0.16 Wherein, f is the total focal length of the lithography lens, D1 is the distance from the object plane to the first lens, and D2 is the distance from the aperture to the image plane; The first lens has positive optical power and is a meniscus lens with its concave surface facing the object plane; the sixth lens has positive optical power and is a meniscus lens with its concave surface facing the image plane; The second lens group includes a second lens, a third lens, a fourth lens, and a fifth lens arranged in sequence, the second lens is arranged on a side close to the first reflector, the fifth lens is arranged on a side close to the second reflector, the second lens, the third lens, and the fourth lens all have positive optical power, and the fifth lens has negative optical power; The second lens is a biconvex lens, the third lens, the fourth lens, and the fifth lens are all meniscus lenses with a concave surface facing the aperture, and the distance between the side of the fifth lens close to the aperture and the aperture is greater than 120 mm; The first reflector and the second reflector are both plane reflectors.

2. The reflective lithography lens according to claim 1, wherein: The first lens satisfies the relationship: 0.41 < f1 / f < 0.43, where f1 is the focal length of the first lens; The sixth lens satisfies the relationship: 0.41 < f6 / f < 0.43, where f6 is the focal length of the sixth lens.

3. The reflective lithography lens according to claim 1, wherein: The first lens and the sixth lens are halves of a same complete spherical lens.

4. The reflective lithography lens according to claim 1 or 2, characterized in that: Place The second lens group satisfies the relationship: 0.1 < f2 / f < 0.12 0.06 < f3 / f < 0.08 0.08 < f4 / f < 0.1 -0.03 < f5 / f < -0.02 Among them, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, and f5 is the focal length of the fifth lens.

5. The reflective lithography lens according to claim 1, wherein: The refractive index of the first lens is in the range of 1.5-1.6, and the chromatic aberration coefficient of the first lens is in the range of 60-65. The refractive index and chromatic aberration coefficient of the second lens, the third lens, the fourth lens, and the sixth lens are in the same range as those of the first lens. The refractive index of the fifth lens is in the range of 1.6-1.7, and the chromatic aberration coefficient of the fifth lens is in the range of 35-40.

6. The reflective lithography lens according to claim 1, wherein: The side of the first lens closest to the object plane is defined as the object plane side, and the side away from the object plane is defined as the image plane side. The range of the curvature radius R1 of the object plane side of the first lens is 1176.96 mm < R1 < 1179.96 mm, and the range of the curvature radius R11 of the image plane side of the first lens is 783.45 mm < R11 < 786.45 mm. The sides of the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens close to the aperture are set as the image side, and the sides away from the aperture are set as the object side, wherein: The curvature radius R2 of the object side of the second lens is in the range of 1129.95 mm < R2 <1132.95 mm, and the curvature radius R21 of the image side of the second lens is in the range of 1277.54 mm < R21 <1280.54 mm. The object side curvature radius R3 of the third lens element has a value range of 296.41 mm < R3 < 299.41 mm, and the image side curvature radius R31 of the third lens element has a value range of 1267.99 mm < R31 < 1270.99 mm. The object-side curvature radius R4 of the fourth lens element has a value range of 286.49 mm < R4 < 289.49 mm, and the image-side curvature radius R41 of the fourth lens element has a value range of 672.46 mm < R41 < 675.46 mm. The object-side curvature radius R5 of the fifth lens element has a value range of 1621.06 mm < R5 < 1624.06 mm, and the image-side curvature radius R51 of the fifth lens element has a value range of 154.14 mm < R51 < 157.14 mm. The value range of the curvature radius R6 on the object side of the sixth lens is 1176.96 mm < R6 < 1179.96 mm, and the value range of the curvature radius R61 on the image side of the sixth lens is 783.45 mm < R61 < 786.45 mm.

7. The reflective lithography lens according to claim 1, wherein: The first lens, the second lens, the third lens, the fourth lens, and the sixth lens are all made of crown glass, and the fifth lens is made of flint glass.

8. The reflective lithography lens according to claim 1, wherein: The photolithography lens is an equal-magnification imaging lens, and the ultraviolet wavelength range used by the photolithography lens is 400nm ≤ λ ≤ 410nm.

Images