Projection lithography objective lens and lithography machine

Abstract

The present invention provides a projection lithography objective lens and a lithography machine. Specifically, the first negative lens and the first positive lens in the first lens group of the projection lithography objective lens form a close-contact double-separated lens group to achieve field curvature / astigmatism correction. The third positive lens, the second negative lens, and the fourth positive lens in the fifth lens group form a close-contact three-separated lens group to achieve chromatic aberration correction. The second lens group, the third lens group, the fourth lens group, and the fifth lens group each include at least one aspherical surface. Because aspherical surfaces increase the degree of freedom of optimization compared to spherical surfaces, one aspherical surface can, in principle, replace the effect of 2-3 spherical lenses. Therefore, in terms of adjusting aberrations, the lens size can be greatly compressed, the number of lenses can be reduced, and the complexity of the structure can be reduced. At the same time, the field of view can be increased and the transmittance can be improved. Therefore, the present invention can improve the imaging quality while increasing the field of view, so as to achieve simultaneous improvement in lithography accuracy and output, and also reduce the number of lenses and reduce costs.

Description

Technical Field

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

[0002] Optical exposure devices, also known as photolithography machines, utilize the principle of optical projection imaging to transfer integrated circuit (IC) patterns from a mask onto a coated silicon wafer in a distributed, repetitive, or scanning manner, thereby fabricating semiconductor devices. However, with increasing market demand and the increasing integration density of integrated circuit devices, the requirements for photolithography precision and throughput are also increasing. Therefore, improving the resolution of photolithography lenses while maintaining high throughput has become a technical challenge in this field.

[0003] It is well known that improving the resolution of lithography can be achieved by shortening the wavelength, increasing the numerical aperture (NA), reducing the process factor, etc. High yield can be achieved by using a large projection objective lens exposure field. However, it is difficult to achieve a large field of view with a large numerical aperture in a projection optical system. Because optical systems can be classified into high numerical aperture small field of view and low numerical aperture large field of view optical systems, if high numerical aperture and large field of view are to be achieved at the same time, the design difficulty will increase exponentially. In addition, in the pure refractive optical system of projection exposure, various requirements similar to the calibration of aberrations will increase with the increase of numerical aperture or field of view. And the weight and size of the projection optical system tend to increase with the increase of the numerical aperture and field of view of these systems, and the cost of the projection objective will also increase.

[0004] Therefore, it is necessary to design a new projection lithography objective lens and lithography machine to achieve both high-resolution and large-field-of-view exposure. Summary of the Invention

[0005] The object of the present invention is to provide a projection lithography objective lens and a lithography machine to solve the problem of how to achieve high resolution and high yield at the same time.

[0006] In order to solve the above technical problems, the present invention provides a projection lithography objective lens, comprising: a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group and a sixth lens group arranged in sequence along an optical path;

[0007] The first lens group includes a first negative lens and a first positive lens arranged in sequence along the optical path, and the side of the first negative lens close to the object plane is aspherical;

[0008] The fifth lens group includes a second positive lens, an aperture stop, a third positive lens, a second negative lens and a fourth positive lens arranged in sequence along the optical path;

[0009] The lenses in the third lens group are all positive lenses; the lenses in the second lens group, the fourth lens group and the sixth lens group are all negative lenses;

[0010] Wherein, each of the second lens group, the third lens group, the fourth lens group and the fifth lens group includes at least one aspherical lens.

[0011] Optionally, in the projection lithography objective lens, the optical power values of the first lens group and the fifth lens group are both positive numbers.

[0012] Optionally, in the projection lithography objective lens, the fifth lens group includes at least one biconcave negative lens, and the biconcave negative lens has at least one aspherical surface.

[0013] Optionally, in the projection lithography objective lens, the first negative lens is a meniscus negative lens, and the first positive lens is a biconvex positive lens.

[0014] Optionally, in the projection lithography objective lens, the first negative lens is a biconcave negative lens, and the first positive lens is a plano-convex positive lens.

[0015] Optionally, in the projection lithography objective lens, the second positive lens, the third positive lens and the fourth positive lens are all biconvex positive lenses, and the second negative lens is a biconcave negative lens.

[0016] Optionally, in the projection lithography objective lens, the second positive lens and the third positive lens are symmetrically distributed about the aperture stop.

[0017] Optionally, in the projection lithography objective lens, the material of the lens in the projection lithography objective lens includes ultraviolet high-transmittance optical glass with a refractive index greater than 1.61 at the working wavelength, and ultraviolet high-transmittance optical glass with a refractive index less than 1.51 at the working wavelength.

[0018] Optionally, in the projection lithography objective lens, the projection lithography objective lens further includes an object plane plate and an image plane plate; wherein, one side of the object plane plate is close to the object plane, and the other opposite side is close to the first lens group; one side of the image plane plate is close to the image plane, and the other opposite side is close to the sixth lens group.

[0019] Optionally, in the projection lithography objective lens, the optical focal lengths of the object plane plate and the image plane plate are zero.

[0020] Based on the same inventive concept, the present invention also provides a lithography machine, which includes the projection lithography objective lens.

[0021] In summary, the present invention provides a projection lithography objective lens and a lithography machine, comprising: a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group, and a sixth lens group, sequentially arranged along an optical path; wherein the first lens group includes a first negative lens and a first positive lens, sequentially arranged along the optical path, and the side of the first negative lens closest to the object plane is aspherical. The first negative lens and the first positive lens form a close-contact double-separated lens group, capable of correcting field curvature and astigmatism over a large field of view.

[0022] The fifth lens group includes a second positive lens, an aperture stop, a third positive lens, a second negative lens, and a fourth positive lens, which are arranged in sequence along the optical path. The third positive lens, the second negative lens, and the fourth positive lens are combined to form a close-contact three-separation lens group, and are arranged close to the aperture stop, which can achieve chromatic aberration correction in a large field of view, thereby further improving the imaging quality in a large field of view.

[0023] The lenses in the third lens group are all positive lenses; the lenses in the second, fourth, and sixth lens groups are all negative lenses, enabling aberration correction over a large field of view. Furthermore, each of the second, third, fourth, and fifth lens groups includes at least one lens with an aspherical surface. Because aspherical surfaces offer increased degrees of freedom for optimization compared to spherical surfaces, a single aspherical lens can, in principle, replace the aberration correction effect of two to three spherical lenses. Therefore, when adjusting aberrations, a single aspherical lens can replace multiple spherical lenses, significantly reducing lens size, the number of lenses, and structural complexity, while also increasing the field of view and improving transmittance. Therefore, the present invention improves image quality while increasing the field of view, thereby simultaneously improving lithography accuracy and throughput, while also reducing the number of lenses and lowering costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the structure of a projection lithography objective lens in embodiment 1 of the present invention;

[0025] Figure 2 is a modulation transfer function curve diagram in the first embodiment of the present invention;

[0026] Figure 3 This is the image wave aberration distribution diagram at the central reference wavelength of 365.3 nm in Example 1 of the present invention;

[0027] Figure 4 is a distorted image surface distribution diagram in the first embodiment of the present invention;

[0028] Figure 5 is a color difference curve diagram in Example 1 of the present invention;

[0029] Figure 6is an aberration curve diagram in Example 1 of the present invention;

[0030] Figure 7 Schematic diagram of the structure of a projection lithography objective lens in embodiment 2 of the present invention;

[0031] Figure 8 is a modulation transfer function curve diagram in the second embodiment of the present invention;

[0032] Figure 9 This is the image wave aberration distribution diagram at the central reference wavelength of 365.3 nm in Example 2 of the present invention;

[0033] Figure 10 is a distorted image plane distribution diagram in the second embodiment of the present invention;

[0034] Figure 11 is a color difference curve diagram in Example 2 of the present invention;

[0035] Figure 12 This is an aberration curve diagram in Example 2 of the present invention. DETAILED DESCRIPTION

[0036] In order to make the objects, advantages and features of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis required to be shown in each drawing is different, and sometimes different scales are used. It should also be understood that, unless otherwise specified or indicated, the terms "first", "second", "third" and the like in the specification are only used to distinguish between the various components, elements, steps, etc. in the specification, and are not used to represent the logical relationship or sequential relationship between the various components, elements, steps, etc.

[0037] <Example 1>

[0038] In order to solve the above technical problems, this embodiment provides a projection lithography objective lens, see Figure 1 The projection lithography objective lens includes: a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, a fifth lens group G5 and a sixth lens group G6, which are arranged in sequence along the optical path.

[0039] The first lens group G1 includes a first negative lens 2 and a first positive lens 3, which are arranged in sequence along the optical path. The side of the first negative lens 2 closest to the object plane is aspherical. Along the optical propagation direction, the first negative lens 2 is arranged at the position closest to the object plane in the first lens group G1, and the first positive lens 3 is arranged immediately adjacent to the first negative lens 2, so that the first negative lens 2 and the first positive lens 3 cooperate with each other to form a close-contact double-separation lens group. Furthermore, the optical powers of the first negative lens 2 and the first positive lens 3 do not compensate for each other, but retain a certain residual combined optical power. In terms of material selection, the difference in the Abbe constant (dispersion) of the optical materials of the first negative lens 2 and the first positive lens 3 is as large as possible. Preferably, the material of the first negative lens 2 is crown glass, and the material of the first positive lens 3 is flint glass. Thus, the close-contact double-separation lens group can correct field curvature / astigmatism of the field of view to improve imaging quality.

[0040] Furthermore, the first negative lens 2 is a meniscus negative lens, the first positive lens 3 is a biconvex positive lens, and the side of the meniscus negative lens facing the object plane is aspherical, so as to improve the correction effect and reduce the number of lenses used. Optionally, the first lens group G1 also includes a biconvex positive lens 4 and a biconvex positive lens 5 to ensure that the overall focal power value of the first lens group G1 is positive. Among them, the focal power is equal to the difference between the convergence of the image-side light beam and the convergence of the object-side light beam, which characterizes the ability of the optical system to deflect light. When the focal power value is positive, the refraction of the light is convergent. The focal power value of the first lens group G1 is positive so that the entire light beam is transmitted to the second lens group G2.

[0041] All lenses in the second lens group G2 are negative lenses and include at least one aspherical surface. Optionally, the second lens group G2 includes a meniscus negative lens 6, a biconcave negative lens 7, and a biconcave negative lens 8. Therefore, the focal power of the second lens group G2 is negative, and the light is diffusively transmitted to the third lens group G3. The second lens group G2 utilizes at least one aspherical surface. Because aspherical surfaces offer increased degrees of freedom for optimization compared to spherical surfaces, a single aspherical surface can, in principle, replace the aberration correction effect of two to three spherical lenses. Therefore, when adjusting aberrations, a single aspherical lens can replace multiple spherical lenses, significantly reducing lens size, the number of lenses, and the complexity of the structure. This can also increase the field of view and improve transmittance.

[0042] All lenses in the third lens group G3 are positive lenses and include at least one aspherical surface. Therefore, the optical power of the third lens group G3 is positive. Optionally, the third lens group G3 includes a meniscus positive lens 9, a biconvex positive lens 10, a convex-plano positive lens 11, and a meniscus positive lens 12. Similarly, the use of aspherical surfaces can correct aberrations and reduce lens usage.

[0043] All lenses in the fourth lens group G4 are negative lenses and include at least one aspherical surface. Therefore, the optical power of the fourth lens group G4 is negative. Optionally, the fourth lens group G4 includes a biconcave negative lens 13 and a biconcave negative lens 14. The inclusion of at least one aspherical surface in the fourth lens group G4 further increases the field of view, corrects aberrations, and reduces the use of lens elements, thereby increasing production throughput by utilizing the large field of view. Furthermore, through correction, the transmittance of the objective lens is improved.

[0044] The fifth lens group G5 comprises, in that order, a second positive lens 16, an aperture stop a, a third positive lens 17, a second negative lens 18, and a fourth positive lens 19. The second positive lens 16 and the third positive lens 17 are symmetrically arranged about the aperture stop a, and the third positive lens 17, the second negative lens 18, and the fourth positive lens 19 are arranged consecutively on one side of the aperture stop a, forming a close-contact three-separated lens group.

[0045] Since the light source of the lithography projection objective lens involved in this embodiment is a mercury lamp, the spectral range used is I-line, which has a certain spectral bandwidth. Therefore, chromatic aberration correction must be performed when designing the projection objective lens. In this regard, the optical focal lengths of the positive and negative lenses in the close-contact three-separation lens group used to achieve chromatic aberration correction do not compensate each other, and a certain residual combined optical focal length is retained. And the difference in the Abbe constants (dispersion) of the two optical materials of the positive and negative lenses is as large as possible. Therefore, flint glass with a high refractive index is preferably used as the material for making the second negative lens 18, and crown glass with a high dispersion is preferably used as the material for making the third positive lens 17 and the fourth positive lens 19, so as to use the close-contact three-separation lens group to correct severe chromatic aberration in a large field of view, so as to ensure transmittance and improve imaging quality.

[0046] Furthermore, the fifth lens group G5 has a positive optical power and includes at least one biconcave negative lens having at least one aspheric surface. Preferably, the second positive lens 16, the third positive lens 17, and the fourth positive lens 19 are all biconvex positive lenses, and the second negative lens 18 is a biconcave negative lens. Furthermore, the fifth lens group G5 also includes a meniscus positive lens 15, a biconvex positive lens 20, a meniscus positive lens 21, a meniscus positive lens 22, and a convex-plano positive lens 23.

[0047] All lenses in the sixth lens group G6 are negative lenses, that is, the optical power value of the sixth lens group G6 is negative. Optionally, the sixth lens group G6 includes a concave flat negative lens 24 to correct aberrations in a large field of view.

[0048] To protect the lenses, the projection lithography objective also includes an object plate 1 and an image plate 25. One side of the object plate 1 is adjacent to the object plane, and the other side is adjacent to the first lens group G1. One side of the image plate 25 is adjacent to the image plane, and the other side is adjacent to the sixth lens group G6. The optical power of the object plate 1 and the image plate 25 is zero.

[0049] Furthermore, the lenses in projection lithography objectives are made of two materials: high-UV-transmittance optical glass with a refractive index greater than 1.61 at the operating wavelength (center reference wavelength) of 365.3nm, such as flint glass; and high-UV-transmittance optical glass with a refractive index less than 1.51 at the operating wavelength (center reference wavelength) of 365.3nm, such as crown glass. High-UV-transmittance optical glass undergoes specific changes under laser irradiation. First, it causes a change in transmittance (solarization), which is primarily manifested in structural changes (densification), geometric changes, thickness reduction, and physical changes (densification), resulting in increased density. Second, it causes a change in optical path difference (primarily due to density changes leading to refractive index changes). This change is affected by the size of the illuminated area, the dose, and the amount of impurities (OH-content), resulting in an increase in the refractive index in the compacted areas and a decrease in the rarefaction areas. Therefore, under UV laser irradiation, the material's refractive index and transmittance vary with the irradiation dose, causing changes in the objective image quality and impacting the life of the lithography tool.

[0050] Therefore, the ultraviolet high-transmittance optical glass selected in this embodiment is used to ensure that the projection lithography objective lens has the characteristic of stable imaging over time. That is, the transmittance of the projection lithography objective lens can be reduced in attenuation rate over time during operation, especially when used for high-productivity wafer exposure. At the same time, this embodiment uses six aspheric lenses, each of which is located on the front surface of the biconcave negative lens 2, the rear surface of the meniscus negative lens 6, the front surface of the biconcave negative lens 8, the front surface of the meniscus positive lens 9, the rear surface of the biconcave negative lens 13, and the rear surface of the biconcave negative lens 18. Among them, all aspheric surfaces are concave surfaces with good processing performance, and the aspheric surface deviation reaches the processing level of the optical industry of less than 1mm. This not only corrects aberrations and improves transmittance, but also reduces the total number of lenses in the entire system, making the entire projection exposure objective lens structure simpler. At the same time, it also effectively controls the incident height of the light beam on each lens and the lens size.

[0051] In order to verify the technical effect of this embodiment, the applicant Figure 1 The projection lithography objective lens shown in the figure is simulated and tested. Among them, the total length of the lithography projection objective lens is 1200mm, the maximum lens semi-aperture is 135.9mm, the object side working distance of the projection objective lens is 32mm, and the image side working distance is 8mm. The i-line ultraviolet spectrum range is selected, the maximum spectrum half-height full width is 2.5nm, the system magnification β is 1 / 4, the numerical aperture of the image side is 0.65, the image side half-field height is 21mm, and the achievable rectangular exposure field size is: 26mm x 33mm. Among them, Figure 1The projection lithography objective shown here implements a dual-telecentric structure. The chief rays of each object-side field of view are incident on the front surface of the first parallel plate approximately parallel to the optical axis. The chief rays of each image-side field of view are emitted approximately parallel to the optical axis and converge on the image plane. The angles with the optical axis are 5.7 mrad on the object side and 1.9 mrad on the image side. Specific experimental parameters are shown in the table below:

[0052] Table 1 Experimental parameters of Example 1

[0053]

[0054]

[0055] Table 2 Refractive index of materials in Example 1

[0056] Material Refractive index relative to nitrogen @365.30nm N2 1 'AIR_N2' 0.999995 'NISF_SN' 1.474501 'SFSL5YUN' 1.504114 'NS5742UN' 1.612672 'NS5859UN' 1.615572 'PBL6YUN' 1.559607

[0057] Table 3 Aspheric coefficients of Example 1

[0058]

[0059]

[0060] In Table 1, a positive radius value indicates that the center of curvature is to the right of the surface, while a negative radius value indicates that the center of curvature is to the left of the surface. A radius of curvature value of 1.00E+18 represents a flat surface. The thickness of an optical element or the spacing between two optical elements is the on-axis distance to the next surface. All dimensions are in millimeters. Table 2 shows the relative refractive index data of the optical materials used in this embodiment relative to nitrogen (N2) at a wavelength of 365.3 nm.

[0061] Table 3 shows the aspheric coefficients corresponding to the surface numbers in Table 1. Furthermore, the calculation formula for the aspheric coefficients in the projection lithography objective lens provided in this embodiment is:

[0062]

[0063] in, x represents the coordinate value in the X direction, y represents the coordinate value in the Y direction, and z represents the axial sagittal height in the Z direction. The X, Y, and Z directions conform to the Cartesian coordinate system. k represents the cone coefficient of the best-fit cone, c represents the curvature (curv) of the best-fit sphere, and A, B, C, D, E, F, G, H, and J all represent aspheric coefficients. Furthermore, in this embodiment, G = 0, H = 0, and J = 0.

[0064] According to the test results: Figure 2 is the Modulation Transfer Function (MTF) curve, from Figure 2It can be seen that the multi-color modulation transfer function is very close to the diffraction limit, which shows that the visual quality produced by the lithography projection objective lens provided by this embodiment is very good. Figure 3 Figure 3 is the distribution diagram of the image wave aberration (WFE) at the central reference wavelength of 365.3nm. It can be seen from the figure that the aberration is eliminated and the imaging in the field of view is good. Figure 4 This is the distorted image distribution diagram. The image distortion is eliminated in the figure, and the imaging is good within the field of view. Figure 5 is the color difference curve, Figure 6 The aberration curve shows that the correction effects of chromatic aberration and aberration are very good. Therefore, the wavefront aberration, distortion correction effect, chromatic aberration correction effect and aberration correction effect produced by the lithography projection objective lens provided in this embodiment are all very good.

[0065] Therefore, the projection lithography objective provided in this embodiment utilizes the characteristics of the aspheric surface to increase the field of view, and utilizes the close-contact double-separation lens group formed by the combination of the first negative lens 2 and the first positive lens 3 to correct the field curvature / astigmatism in the large field of view. At the same time, the third positive lens 17, the second negative lens 18 and the fourth positive lens 19 are combined to form a close-contact three-separation lens group to correct chromatic aberration in the large field of view, so as to further improve the imaging quality of the large field of view, improve the resolution and imaging quality, so as to simultaneously achieve the purpose of improving lithography accuracy and output, and also reduce the number of lenses and reduce costs.

[0066] Based on the same inventive concept, this embodiment further provides a lithography machine, which includes a projection lithography objective lens.

[0067] <Example 2>

[0068] On the basis of the same inventive concept, in order to further reduce the number of lenses used and lower the cost, this embodiment provides a projection lithography objective lens, see Figure 7 The projection lithography objective lens includes: a first lens group G1', a second lens group G2', a third lens group G3', a fourth lens group G4', a fifth lens group G5' and a sixth lens group G6' which are sequentially arranged along the optical path.

[0069] Among them, the first lens group G1' has positive optical focal length, including: a biconcave negative lens 2' and a plano-convex positive lens 3', a biconvex positive lens 4' and a biconvex positive lens 5', wherein the first negative lens is a biconcave negative lens 2', and the first positive lens is a plano-convex positive lens 3', which are used to form a close-contact double-separated lens group for field curvature / astigmatism correction. The second lens group G2' has a negative combined optical focal length, consisting of three lenses, namely, a meniscus negative lens 6', a biconcave negative lens 7' and a biconcave negative lens 8'. The third lens group G3' has a positive combined optical focal length, consisting of three lenses, namely, a meniscus positive lens 9', a biconvex positive lens 10', and a convex-plano positive lens 11'. The fourth lens group G4' has a negative combined optical focal length, consisting of two lenses, namely, a biconcave negative lens 12' and a biconcave negative lens 13'. The fifth lens group G5' has a positive combined optical power and consists of seven lenses and an aperture stop a'. The seven lenses are a biconvex positive lens 14' and a biconvex positive lens 15', a biconcave negative lens 16', a biconvex positive lens 17', a convex-plano positive lens 18', a meniscus positive lens 19', and a convex-plano positive lens 20'. The second positive lens is a biconvex positive lens 14', the third positive lens is a biconvex positive lens 15', the second negative lens is a biconcave negative lens 16', and the fourth positive lens is a biconvex positive lens 17'. The biconvex positive lens 14' and the biconvex positive lens 15' are symmetrically arranged about the aperture stop a'. The biconvex positive lens 15', the biconcave negative lens 16', and the biconvex positive lens 17' form a close-contact three-separation lens group for correcting chromatic aberration of the field of view. The sixth lens group G6' has a negative combined optical power and consists of a concave-plano negative lens 21'.

[0070] Similarly, the projection lithography objective lens provided in this embodiment also includes an object plate 1' and an image plate 22'. One side of the object plate 1' is adjacent to the object plane, and the opposite side is adjacent to the first lens group G1'. One side of the image plate 22' is adjacent to the image plane, and the opposite side is adjacent to the sixth lens group G6'. The optical power of the object plate 1' and the image plate 22' is zero. Compared to the first embodiment, this embodiment saves three lenses.

[0071] Furthermore, the projection lithography objective provided in this embodiment includes 9 aspheric surfaces, namely: the front surface of the double concave negative lens 2', the rear surface of the meniscus negative lens 6', the front surface of the double concave negative lens 8', the front surface of the meniscus positive lens 9', the rear surface of the double concave negative lens 12', the rear surface of the double concave negative lens 13', the rear surface of the double concave negative lens 16', the rear surface of the meniscus positive lens 19', and the front surface of the concave flat negative lens 21'. Among them, all the aspheric surfaces are concave surfaces with good processing performance, and the aspheric surface deviation reaches the processing level of the optical industry <1mm. This not only corrects the aberration and improves the transmittance, but also reduces the total number of lenses in the entire system, making the entire projection exposure objective structure simpler. At the same time, it also effectively controls the incident height of the light beam on each lens and the size of the lens.

[0072] For details not provided in this embodiment, please refer to the description in the first embodiment.

[0073] In order to verify the imaging effect of the projection lithography objective lens provided in this embodiment, the applicant Figure 7 The projection lithography objective lens shown in the figure was simulated and tested. The total length of the projection lithography objective lens is 1250mm, the maximum lens semi-aperture is 142.9mm, the object side working distance is 32mm, and the image side working distance is 8mm. It is suitable for the i-line ultraviolet spectrum range, the maximum spectrum half-height full width is 2.5nm, the system magnification β is 1 / 4, the numerical aperture of the image side is 0.65, the image side half-field height is 21mm, and the achievable rectangular exposure field size is: 26mmx33mm. In addition, this embodiment realizes a double telecentric structure, and the main light of each field of view on the object side is approximately parallel to the optical axis and incident on the front surface of the first parallel flat plate; the main light of each field of view on the image side is approximately parallel to the optical axis and emerges, converging on the image plane. The angles with the optical axis are: 5mrad on the object side and 2.5mrad on the image side.

[0074] Specific experimental parameters are shown in the table below:

[0075] Table 4 Experimental parameters of Example 2

[0076]

[0077]

[0078] Table 5 Refractive index of materials in Example 2

[0079] Material Refractive index relative to nitrogen @365.30nm N2 1 'AIR_N2' 0.999995 'NISF_SN' 1.474501 'SFSL5YUN' 1.504114 'NS5742UN' 1.612672 'NS5859UN' 1.615572 'PBL6YUN' 1.559607

[0080] Table 6 Aspheric coefficients of Example 2

[0081]

[0082]

[0083] Among them, the positive radius value in Table 4 indicates that the center of curvature is on the right side of the surface, and the negative radius value indicates that the center of curvature is on the left side of the surface. The curvature radius value of 1.00E+18 represents a plane. The thickness of an optical element or the spacing between two optical elements is the axial distance to the next surface. All dimensions are in millimeters. Table 5 shows the relative refractive index data of the optical materials used in this embodiment with respect to nitrogen (N2) at a wavelength of 365.3nm. Table 6 shows the aspheric coefficients corresponding to the surface numbers in Table 4. Please refer to Example 1 for the specific calculation formula, where G=0, H=0, and J=0.

[0084] According to the test results: Figure 8is the Modulation Transfer Function (MTF) curve, from Figure 8 It can be seen that the multi-color modulation transfer function is very close to the diffraction limit, which shows that the visual quality produced by the lithography projection objective lens provided by this embodiment is very good. Figure 9 is the image wavefront aberration (WFE) distribution diagram at the central reference wavelength of 365.3nm, Figure 10 is the distorted image distribution diagram, Figure 11 is the color difference curve, Figure 12 is the aberration curve. It can be seen that the lithography projection objective lens provided in this embodiment produces excellent wavefront aberration, distortion correction, chromatic aberration correction, and aberration correction effects. Therefore, based on the first embodiment, this embodiment not only achieves a large field of view and high resolution, but also reduces the use of lenses.

[0085] In summary, Examples 1 and 2 provide a projection lithography objective lens and a lithography machine. The projection lithography objective lens comprises: a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group, and a sixth lens group, sequentially arranged along an optical path. The first lens group comprises a first negative lens and a first positive lens, and the side of the first negative lens closest to the object plane is aspherical. The first negative lens and the first positive lens form a close-contact double-separated lens group, which can correct field curvature and astigmatism over a wide field of view. The fifth lens group comprises a second positive lens, an aperture stop, a third positive lens, a second negative lens, and a fourth positive lens, sequentially arranged along the optical path. The third positive lens, the second negative lens, and the fourth positive lens form a close-contact three-separated lens group, which is positioned close to the aperture stop and can correct chromatic aberration over a wide field of view, further improving imaging quality over a wide field of view. The lenses in the third lens group are all positive lenses; the lenses in the second, fourth, and sixth lens groups are all negative lenses, which can correct aberration over a wide field of view. Each of the second, third, fourth, and fifth lens groups includes at least one aspherical surface. Because aspherical surfaces offer increased degrees of freedom in optimization compared to spherical surfaces, a single aspherical surface can, in principle, replace the aberration correction effect of two or three spherical lenses. Therefore, when adjusting aberrations, a single aspherical lens can replace multiple spherical lenses, significantly reducing lens size, the number of lenses, and structural complexity. This also increases the field of view and transmittance. Therefore, this embodiment improves image quality while increasing the field of view, thereby simultaneously enhancing lithography accuracy and throughput, while also reducing the number of lenses and lowering costs.

[0086] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other. In addition, the different parts between the various embodiments can also be used in combination with each other, and the present invention is not limited to this.

[0087] Furthermore, it should be recognized that although the present invention has been disclosed above with reference to preferred embodiments, the above embodiments are not intended to limit the present invention. Any person skilled in the art can utilize the above disclosed technical content to make many possible changes and modifications to the technical solution of the present invention, or modify it into equivalent embodiments with equivalent variations, without departing from the scope of the technical solution of the present invention. Therefore, any simple modifications, equivalent variations, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A projection lithography objective lens, characterized in that: include: a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group, and a sixth lens group arranged in sequence along the optical path; The first lens group includes a first negative lens and a first positive lens arranged in sequence along the optical path, and the side of the first negative lens close to the object plane is aspherical; The fifth lens group includes a second positive lens, an aperture stop, a third positive lens, a second negative lens and a fourth positive lens arranged in sequence along the optical path; The lenses in the third lens group are all positive lenses; The lenses in the second lens group, the fourth lens group and the sixth lens group are all negative lenses; Wherein, each of the second lens group, the third lens group, the fourth lens group and the fifth lens group includes at least one aspherical lens.

2. The projection lithography objective lens according to claim 1, wherein: The optical power values of the first lens group and the fifth lens group are both positive numbers.

3. The projection lithography objective lens according to claim 1, wherein: The fifth lens group includes at least one biconcave negative lens, and the biconcave negative lens has at least one aspherical surface.

4. The projection lithography objective lens according to claim 1, wherein: The first negative lens is a meniscus negative lens, and the first positive lens is a biconvex positive lens.

5. The projection lithography objective lens according to claim 1, wherein: The first negative lens is a biconcave negative lens, and the first positive lens is a plano-convex positive lens.

6. The projection lithography objective lens according to claim 1, wherein: The second positive lens, the third positive lens and the fourth positive lens are all biconvex positive lenses, and the second negative lens is a biconcave negative lens.

7. The projection lithography objective lens according to claim 1, wherein: The second positive lens and the third positive lens are symmetrically distributed with respect to the aperture stop.

8. The projection lithography objective lens according to claim 1, wherein: The material of the lens in the projection lithography objective lens includes ultraviolet high-transmittance optical glass with a refractive index greater than 1.61 at the working wavelength, and ultraviolet high-transmittance optical glass with a refractive index less than 1.51 at the working wavelength.

9. The projection lithography objective lens according to claim 1, wherein: The projection lithography objective lens further includes an object plane plate and an image plane plate; wherein one side of the object plane plate is close to the object plane, and the other side thereof is close to the first lens group; one side of the image plane plate is close to the image plane, and the other side thereof is close to the sixth lens group.

10. The projection lithography objective lens according to claim 9, characterized in that: The optical power of the object plane plate and the image plane plate is zero.

11. A photolithography machine, characterized in that: The lithography machine includes the projection lithography objective lens according to any one of claims 1 to 10.

Images