Illumination System and Exposure Device Based on Spherical Waves

Abstract

The present invention discloses an illumination system and an exposure device based on spherical waves, which are applied to the field of holographic lithography technology. The holographic lithography illumination system includes: a first lens group, a second lens group, and a third lens group sequentially arranged along the optical axis direction; the first lens group is used to receive the input laser; the second lens group is used to expand the received laser; the third lens group is used to converge the expanded laser and output spherical wave laser in the direction of the holographic mask. The present invention can greatly improve the resolution of lithography imaging through the holographic mask only by using the cooperation of three lens groups, thereby ensuring the exposure yield. Compared with traditional projection lithography, the number of lenses used can be greatly reduced, and the manufacturing cost can be significantly reduced.

Description

Technical Field

[0001] The present invention relates to the field of holographic lithography technology, and particularly relates to an illumination system and an exposure device based on a spherical wave. Background Art

[0002] Lithography is an integrated circuit manufacturing technology, which is a key process in the production and manufacturing of large-scale integrated circuits, and is a technology that uses a laser to image a mask pattern onto a silicon wafer. Since the 1960s, the structural forms of lithography machines have gone through development stages such as contact type, proximity type, scanning projection type, distributed projection type, and step-and-scan projection lithography machines. The traditional projection lithography system uses the principle of optical projection imaging, and projects the pattern on the mask onto the substrate through the use of lenses or mirrors for exposure. The optical path in this technology is complex, the cost is high, the volume is large, the available optical materials for deep ultraviolet light in the 193nm band are single, the manufacturing difficulty is great, and an additional projection objective lens is required to form a complex optical system. The integrated circuit threads that can be processed by the traditional projection exposure lithography method are limited by the projection objective lens. In the field of traditional projection lithography, the projection lithography objective lens with a working wavelength in the 193nm band is the core component of a projection lithography device for making ultra-fine patterns. At present, the structure of the projection lithography objective lens is complex, the manufacturing is difficult, and the price is expensive. Most systems with a numerical aperture of 0.7 have high-order aspherical surfaces, a long conjugate distance, and a large system volume. For example, patent US20030030916A1 introduces a projection lithography objective lens with a maximum numerical aperture of 0.89, which includes at least 4 lens groups and is composed of 29 lenses in total. Each lens group has a positive or negative optical power, and multiple lens groups are required to expand and focus the light beam multiple times. The number of lenses required is large and the structure is complex. Therefore, a new lithography technology that simplifies the number of lenses, has low cost, and is highly integrated will promote the development of the lithography and semiconductor fields. Summary of the Invention

[0003] In view of this, the present invention provides an illumination system and an exposure device based on a spherical wave, which can overcome the technical problems of the existing lithography illumination system having a large number of lenses and a complex structure.

[0004] The first aspect of the present invention provides an illumination system based on a spherical wave, which is applied to holographic lithography, and includes a first lens group, a second lens group, and a third lens group sequentially arranged along the optical axis direction; the first lens group is used to receive the input laser; the second lens group is used to expand the received laser; the third lens group is used to converge the expanded laser and output spherical wave laser in the direction of the holographic mask.

[0005] Optionally, the first lens group includes a first negative lens and a first meniscus lens arranged in sequence along the optical axis direction; the incident surface of the first negative lens has a negative curvature radius, and its exit surface has a positive curvature radius, which is used to receive the input laser and perform preliminary beam expansion; the incident surface of the first meniscus lens has a positive curvature radius, and its exit surface has a positive curvature radius, which is used to further expand the laser beam that has undergone preliminary beam expansion; wherein, the absolute value of the curvature radius of the exit surface of the first meniscus lens is less than the absolute value of the curvature radius of the incident surface of the first meniscus lens, and the beam expansion ability of the first meniscus lens is stronger than that of the first negative lens.

[0006] Optionally, the distance d1 between the first negative lens and the first meniscus lens satisfies: 11.925 mm ≤ d1 ≤ 11.965 mm.

[0007] Optionally, the illumination system based on spherical waves further includes a second negative lens arranged along the optical axis between the first lens group and the second lens group; the incident surface of the second negative lens has a negative curvature radius, and its exit surface has a positive curvature radius; wherein, the absolute value of the curvature radius of the exit surface of the second negative lens is greater than 600 mm.

[0008] Optionally, the illumination system based on spherical waves further includes a compensation mechanism, the compensation mechanism is connected to the second negative lens, the compensation mechanism is used to drive the second negative lens to move along the optical axis between the first lens group and the second lens group, and the optical path compensation is realized by adjusting the position of the second negative lens on the optical axis. The moving range Δl of the second negative lens satisfies with reference to the starting position of the second negative lens: -1.5 mm ≤ Δl ≤ +1.5 mm.

[0009] Optionally, the second lens group includes a third negative lens, a first positive lens, a fourth negative lens, a first meniscus lens group, and a second positive lens arranged in sequence along the optical axis direction; the incident surface of the third negative lens has a negative curvature radius, and its exit surface has a positive curvature radius, which is used to expand the light beam incident through the first lens group; the incident surface of the first positive lens has a positive curvature radius, and its exit surface is a plane, which is used to converge the laser incident through the third negative lens to limit the beam expansion effect of the third negative lens; the incident surface of the fourth negative lens is a plane, and its exit surface has a positive curvature radius, which is used to enhance the beam expansion of the laser incident through the first positive lens; the first meniscus lens group is used to enhance the beam expansion effect of the laser incident through the fourth negative lens and maintain the light trace of the laser in the propagation path; the incident surface of the second positive lens has a positive curvature radius, and its exit surface has a negative curvature radius, which is used to convert the laser incident through the first meniscus lens group into a quasi-collimated beam.

[0010] Optionally, the first meniscus lens group includes a second meniscus lens, a third meniscus lens, and a fourth meniscus lens arranged in sequence along the optical axis direction; the incident surfaces of the second meniscus lens, the third meniscus lens, and the fourth meniscus lens all have negative curvature radii; the exit surfaces of the second meniscus lens, the third meniscus lens, and the fourth meniscus lens all have negative curvature radii; wherein, the absolute value of the curvature radius of the incident surface of the third meniscus lens is greater than the absolute value of the curvature radius of the exit surface of the third meniscus lens; the absolute value of the curvature radius of the exit surface of the third meniscus lens is less than the absolute value of the curvature radius of the exit surface of the fourth meniscus lens; the absolute value of the curvature radius of the incident surface of the fourth meniscus lens is greater than the absolute value of the curvature radius of the exit surface of the fourth meniscus lens; the second meniscus lens is used to enhance the beam expansion effect of the laser incident through the fourth negative lens; the third meniscus lens and the fourth meniscus lens are used to maintain the light path of the laser incident through the second meniscus lens.

[0011] Optionally, the distances between adjacent two of the third negative lens, the first positive lens, the fourth negative lens, the second meniscus lens, the third meniscus lens, the fourth meniscus lens, and the second positive lens satisfy:

[0012] d9 < d4 < d5 < d6 < d7 < d8

[0013] Wherein, d4 is the distance between the third negative lens and the first positive lens, d5 is the distance between the first positive lens and the fourth negative lens, d6 is the distance between the fourth negative lens and the second meniscus lens, d7 is the distance between the second meniscus lens and the third meniscus lens, d8 is the distance between the third meniscus lens and the fourth meniscus lens, and d9 is the distance between the fourth meniscus lens and the second positive lens.

[0014] Optionally, the third lens group includes a third positive lens and a second meniscus lens group arranged in sequence along the optical axis direction; the incident surface of the third positive lens has a positive curvature radius, and its exit surface is a plane, which is used to preliminarily converge the laser incident through the second lens group; the second meniscus lens group is used to further enhance the converging effect of the laser incident through the third positive lens and output spherical wave laser towards the holographic mask template direction.

[0015] Optionally, the second meniscus lens group includes a fifth meniscus lens, a sixth meniscus lens, and a seventh meniscus lens arranged in sequence along the optical axis direction; the incident surfaces of the fifth meniscus lens, the sixth meniscus lens, and the seventh meniscus lens all have positive curvature radii; the exit surfaces of the fifth meniscus lens, the sixth meniscus lens, and the seventh meniscus lens all have positive curvature radii; the absolute value of the curvature radius of the incident surface of the third positive lens, the absolute value of the curvature radius of the incident surface of the fifth meniscus lens, the absolute value of the curvature radius of the incident surface of the sixth meniscus lens, and the absolute value of the curvature radius of the incident surface of the seventh meniscus lens decrease in sequence; the absolute value of the curvature radius of the exit surface of the third positive lens, the absolute value of the curvature radius of the exit surface of the fifth meniscus lens, the absolute value of the curvature radius of the exit surface of the sixth meniscus lens, and the absolute value of the curvature radius of the exit surface of the seventh meniscus lens decrease in sequence.

[0016] Optionally, the distances between adjacent two of the third positive lens, the fifth meniscus lens, and the sixth meniscus lens satisfy:

[0017] d11 > d12, and d11 > d13

[0018] Wherein, d11 is the distance between the third positive lens and the fifth meniscus lens, d12 is the distance between the fifth meniscus lens and the sixth meniscus lens, and d13 is the distance between the sixth meniscus lens and the seventh meniscus lens.

[0019] Optionally, the distances between the second positive lens and the third positive lens, between the seventh meniscus lens and the holographic mask plate, and between the holographic mask plate and the focal plane satisfy:

[0020] d14 > d10 > d15

[0021] Wherein, d10 is the distance between the second positive lens and the third positive lens, d14 is the distance between the seventh meniscus lens and the holographic mask plate, and d15 is the distance between the holographic mask plate and the focal plane.

[0022] Optionally, a diaphragm is provided between the second lens group and the third lens group.

[0023] In a second aspect of the present invention, an exposure device is provided, which is applied to a chip preparation process, and the exposure device includes the spherical wave-based illumination system according to any one of the first aspect.

[0024] The spherical wave-based illumination system and the exposure device of the present invention at least have the following beneficial effects:

[0025] The illumination system and exposure device based on spherical waves of the present invention receive the laser emitted by the light source through the first lens group, and then expand the received laser through the second lens group, which can make the beam expansion process more stable and achieve progressive beam expansion. The expanded laser is converged through the third lens group, and the light beam propagates in the form of spherical waves towards the direction of the holographic mask. After passing through the holographic mask, the light beam diffracts and forms an image on the focal plane, that is, an image is formed on the silicon wafer. The convergence through the third lens group enables the holographic lithography illumination system to obtain a larger numerical aperture. In the case of only using three lens groups in cooperation, the resolution of lithography imaging through the holographic mask is greatly improved, thereby ensuring the exposure yield. Compared with traditional projection lithography, the number of lenses used can be greatly reduced, and the manufacturing cost can be significantly reduced. Description of the Drawings

[0026] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 Schematic optical path diagram of the illumination system based on spherical waves according to an embodiment of the present invention;

[0028] Figure 2 Schematic structural diagram of the illumination system based on spherical waves according to an embodiment of the present invention;

[0029] Figure 3 Schematic optical path diagram of the outgoing light of the illumination system based on spherical waves according to an embodiment of the present invention;

[0030] Figure 4 Schematic diagram of the optical modulation transfer function of the illumination system based on spherical waves according to an embodiment of the present invention;

[0031] Figure 5 Schematic diagram of the root mean square wave aberration of the illumination system based on spherical waves according to an embodiment of the present invention at a 0.00° field of view;

[0032] Figure 6 Schematic diagram of the root mean square wave aberration of the illumination system based on spherical waves according to an embodiment of the present invention at a 0.05° field of view;

[0033] Figure 7 Schematic diagram of the root mean square wave aberration of the illumination system based on spherical waves according to an embodiment of the present invention at a 0.1° field of view.

[0034] Explanation of the reference numerals in the drawings:

[0035] 1 - First negative lens; 2 - First meniscus lens; 3 - Second negative lens; 4 - Third negative lens; 5 - First positive lens; 6 - Fourth negative lens; 7 - Second meniscus lens; 8 - Third meniscus lens; 9 - Fourth meniscus lens; 10 - Second positive lens; 11 - Third positive lens; 12 - Fifth meniscus lens; 13 - Sixth meniscus lens; 14 - Seventh meniscus lens; 15 - Holographic mask; 16 - Focal plane. Detailed implementation manners

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "front", "rear", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0038] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "arranged", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0039] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] A holographic lithography system is a technology that uses a laser to image the pattern on a holographic mask onto a substrate such as a silicon wafer, and can be used for the manufacture of integrated circuits. Compared with projection lithography, holographic lithography has lower process requirements for the illumination system. There is no object-image relationship between the mask and the silicon wafer, which can avoid the dependence on the projection objective lens in conventional projection lithography. In a holographic lithography system, the performance of the holographic lithography illumination system is the key in holographic lithography technology, which directly determines the pattern transfer ability of the entire exposure device.

[0041] In the field of holographic lithography, the main work focuses on how to improve the calculation of holographic masks. Currently, there is no illumination system designed based on the characteristics of holographic lithography. Instead, a light source is directly used to irradiate the holographic mask for projection, resulting in poor imaging effects. Moreover, using a projection lithography objective lens leads to structural redundancy. Therefore, there is an urgent need for an illumination system with a simple structure that meets the requirements of holographic lithography technology.

[0042] Currently, the illumination systems of holographic lithography systems are divided into an illumination system based on spherical waves and an illumination system based on plane waves. The illumination system based on spherical waves requires the laser output by the light source to propagate to the mask in the form of spherical waves, and the illumination system requires a relatively large numerical aperture to improve the lithography resolution.

[0043] Based on this, an embodiment of the present invention proposes an illumination system based on spherical waves, which is applied to holographic lithography. Please refer to Figure 1 、 Figure 2 and Figure 3 . The illumination system based on spherical waves includes a first lens group, a second lens group, and a third lens group arranged in sequence along the optical axis direction; the first lens group is used to receive the input laser; the second lens group is used to expand the received laser; the third lens group is used to converge the expanded laser and output spherical wave laser in the direction of the holographic mask 15.

[0044] Specifically, the function of the first lens group is to receive the laser, enabling the laser entering the illumination system to enter smoothly, stabilizing the light beam, and achieving progressive beam expansion. Therefore, the first lens group uses lenses with a relatively large absolute value of the radius of curvature to play a role in stabilizing the light beam.

[0045] The second lens group includes multiple lenses, mainly formed by one or a combination of positive lenses, negative lenses, or meniscus lenses. The second lens group has a total negative optical power, so that the second lens group can further expand the laser output by the light source in a progressive manner.

[0046] The third lens group includes multiple lenses, mainly formed by one or a combination of positive lenses, negative lenses, or meniscus lenses. The second lens group has a total negative optical power, and the third lens group has a total positive optical power. The spherical aberrations generated by the two are opposite and will partially cancel each other, thereby reducing the total spherical aberration of the illumination system and ensuring progressive and stable convergence.

[0047] The lenses used in the first lens group, the second lens group, and the third lens group can be made of ultraviolet fused quartz or calcium fluoride, so as to have good transmittance for ultraviolet light in the 193nm band.

[0048] The centers of all the lenses used in the first lens group, the second lens group, and the third lens group are all on the optical axis, and their relative positions are fixed by setting mechanical components on the lens frames.

[0049] An illumination system based on spherical waves according to an embodiment of the present invention receives the laser emitted by a light source through a first lens group, and then expands the received laser through a second lens group, which can make the beam expansion process more stable and achieve gradual beam expansion. The expanded laser is converged through a third lens group, and the light beam propagates in the form of spherical waves towards the direction of the holographic mask. After passing through the holographic mask, the light beam diffracts and forms an image on the focal plane 16, that is, an image is formed on the silicon wafer. The progressive and stable convergence through the third lens group enables the holographic lithography illumination system to obtain a large numerical aperture. Therefore, when only three lens groups are used in cooperation, the resolution of lithography imaging through the holographic mask can be greatly improved, thereby ensuring the exposure yield. Compared with traditional projection lithography, the number of lenses used can be greatly reduced, and the manufacturing cost can be significantly reduced.

[0050] In some alternative embodiments, the first lens group includes a first negative lens 1 and a first meniscus lens 2 arranged in sequence along the optical axis direction; the incident surface of the first negative lens 1 has a negative curvature radius, and its exit surface has a positive curvature radius, which is used to receive the input laser and perform preliminary beam expansion; the incident surface of the first meniscus lens 2 has a positive curvature radius, and its exit surface has a positive curvature radius, which is used to further expand the laser beam that has undergone preliminary beam expansion; wherein, the absolute value of the curvature radius of the exit surface of the first meniscus lens 2 is less than the absolute value of the curvature radius of the incident surface of the first meniscus lens 2, and the beam expansion ability of the first meniscus lens 2 is stronger than that of the first negative lens 1.

[0051] It should be understood that in the embodiments of the present invention, the incident surface is the surface close to the light source, that is, the front surface, and the exit surface is the surface close to the holographic mask 15, that is, the rear surface.

[0052] The incident surface of the first negative lens 1, that is, the front surface, is a concave surface with a negative curvature radius, which is used to receive the light beam of the laser. After the light beam refracts on this surface, it will undergo preliminary beam expansion. The exit surface of the first negative lens 1, that is, the rear surface, is a concave surface with a positive curvature radius, which is used for the refraction and beam expansion of the light beam.

[0053] The incident surface of the first meniscus lens 2, that is, the front surface, is a convex surface with a positive curvature radius. The light beam will have a converging effect after refracting here, that is, the beam expansion of the light beam will be postponed. The exit surface of the first meniscus lens 2 is a concave surface with a positive curvature radius, which is used to further expand the light beam. At this time, the absolute value of the curvature radius is smaller, that is, the absolute value of the curvature radius of the exit surface of the first meniscus lens 2 is at least less than the absolute value of the curvature radius of the incident surface of the first meniscus lens 2.

[0054] Specifically, the value range of the radius of curvature r11 of the front surface of the first negative lens 1 is: -83.591 mm ≤ r11 ≤ -83.551 mm, the value range of the radius of curvature r12 of the rear surface of the first negative lens 1 is: 31.171 mm ≤ r12 ≤ 31.211 mm, the value range of the radius of curvature r21 of the front surface of the first meniscus lens 2 is: 65.16 mm ≤ r21 ≤ 65.56 mm, the value range of the radius of curvature r22 of the rear surface of the first meniscus lens 2 is: 8.926 mm ≤ r22 ≤ 8.966 mm. The absolute value of the radius of curvature of the light-emitting surface of the first meniscus lens 2 is relatively small, making it have a strong beam expansion ability. The beam expansion ability of the first meniscus lens 2 is stronger than that of the first negative lens 1, realizing the stable reception and expansion of the light beam. And the combination of one concave and one convex of the first meniscus lens 2 will cancel out the radii of curvature with each other, thereby eliminating the axial spherical aberration.

[0055] In some alternative embodiments, the distance d1 between the first negative lens 1 and the first meniscus lens 2 satisfies: 11.925 mm ≤ d1 ≤ 11.965 mm. Exemplarily, the distance d1 between the first negative lens 1 and the first meniscus lens 2 is 11.945 mm.

[0056] When the value range of the distance d1 between the first negative lens 1 and the first meniscus lens 2 is 11.925 mm ≤ d1 ≤ 11.965 mm, a stable light beam can be achieved, realizing the effect of gradual beam expansion.

[0057] In some alternative embodiments, the illumination system based on a spherical wave further includes a second negative lens 3 disposed along the optical axis between the first lens group and the second lens group; the light-incident surface of the second negative lens 3 has a negative radius of curvature, and its light-emitting surface has a positive radius of curvature; wherein, the absolute value of the radius of curvature of the light-emitting surface of the second negative lens 3 is greater than 600 mm.

[0058] Specifically, the light-incident surface of the second negative lens 3 is a concave surface with a negative radius of curvature, which can expand the light beam. The light-emitting surface of the second negative lens 3 is a concave surface with a positive radius of curvature, realizing further beam expansion. Moreover, since the absolute value of its radius of curvature is greater than 600 mm, exemplarily, its radius of curvature is 626.593 mm, and its beam expansion ability is weak, maintaining the original beam expansion light trace.

[0059] In some alternative embodiments, the illumination system based on spherical waves further includes a compensation mechanism. The compensation mechanism is connected to the second negative lens 3. The compensation mechanism is used to drive the second negative lens 3 to move along the optical axis between the first lens group and the second lens group. Optical path compensation is achieved by adjusting the position of the second negative lens 3 on the optical axis. The movement range of the second negative lens 3 with reference to its starting position satisfies: -1.5 mm ≤ Δl ≤ +1.5 mm, where Δl represents the movement range.

[0060] Specifically, the compensation mechanism employs a mechanical translation micromotion stage for carrying the second lens, or a micromotor connected to the second lens through an output shaft. The second negative lens 3 is driven to move along the optical axis by the mechanical translation micromotion stage or the micromotor to adjust the position of the second negative lens 3 on the optical axis.

[0061] During the lithography process, the holographic mask 15 is replaced. The thickness of each holographic mask may be different. Therefore, a compensation mechanism is added here to adjust the position of the second negative lens 3 on the optical axis, that is, the second lens is driven to move back and forth along the optical axis by the compensation mechanism, so as to compensate for the tolerance caused by the thickness of the holographic mask 15. The stroke of the compensation mechanism is ±1.5 mm, and the precision is 0.1 μm, so that the movement range of the second negative lens 3 with reference to its starting position satisfies: -1.5 mm ≤ Δl ≤ +1.5 mm. Therefore, the distance between the second negative lens 3 and the first lens group and the distance between the second negative lens 3 and the second lens group can be adjusted within this range, thereby realizing the compensation for the thickness tolerance of the holographic mask 15.

[0062] In some alternative embodiments, the second lens group includes a third negative lens 4, a first positive lens 5, a fourth negative lens 6, a first meniscus lens group, and a second positive lens 10 arranged in sequence along the optical axis direction; the incident surface of the third negative lens 4 has a negative curvature radius, and its exit surface has a positive curvature radius, which is used to expand the beam incident from the first lens group; the incident surface of the first positive lens 5 has a positive curvature radius, and its exit surface is a plane, which is used to converge the laser incident from the third negative lens 4 to limit the beam expansion effect of the third negative lens 4; the incident surface of the fourth negative lens 6 is a plane, and its exit surface has a positive curvature radius, which is used to expand and enhance the laser incident from the first positive lens 5; the first meniscus lens group is used to enhance the beam expansion effect of the laser incident from the fourth negative lens 6 and maintain the light path of the laser in the propagation path; the incident surface of the second positive lens 10 has a positive curvature radius, and its exit surface has a negative curvature radius, which is used to convert the laser incident from the first meniscus lens group into a quasi-collimated beam.

[0063] Specifically, the light incident surface of the third negative lens 4 is a concave surface with a negative radius of curvature and a relatively large absolute value of the radius of curvature, and the absolute value of the radius of curvature is greater than 450 mm, which is used to receive the light beam emitted from the rear surface of the second negative lens 3 and further expand the beam; the light exit surface of the third negative lens 4 is a concave surface with a positive radius of curvature and a relatively large radius of curvature, and the absolute value of the radius of curvature is greater than 300 mm, which is used to continuously expand the expanded light beam. By using a relatively large absolute value of the radius of curvature, the light path of the expanded laser can be maintained.

[0064] The light incident surface of the first positive lens 5 is a convex surface with a positive radius of curvature and a relatively large absolute value of the radius of curvature, and the absolute value of the radius of curvature is greater than 780 mm, which is used to receive the light beam emitted from the rear surface of the third negative lens 4 and converge the expanded light beam to limit the degree of beam expansion. The light exit surface of the first positive lens 5 is a plane, which is used to receive the light beam incident on the front surface of the first positive lens 5 and maintain the light path of the expanded light beam.

[0065] The light incident surface of the fourth negative lens 6 is a plane with an infinite radius of curvature. The light exit surface of the fourth negative lens 6 is a concave surface with a positive radius of curvature, which is used to further expand the light beam. By first reducing the beam expansion effect with the first positive lens 5 and then enhancing the beam expansion effect with the fourth negative lens 6, the beam expansion process can be carried out smoothly, making the light beam more stable during the beam expansion process.

[0066] The first meniscus lens group is used for beam expansion. By utilizing the characteristics of one concave and one convex surface of the front and rear surfaces of the lenses in the meniscus lens group, spherical aberration can be reduced.

[0067] The first positive lens 5 is used to convert the laser beam emitted from the first meniscus lens 2 into a quasi-collimated beam, that is, to make the laser as collimated as possible, which is beneficial for the third lens group to receive and converge the light beam.

[0068] Further, the first meniscus lens group includes a second meniscus lens 7, a third meniscus lens 8, and a fourth meniscus lens 9 arranged in sequence along the optical axis direction. The incident light surfaces of the second meniscus lens 7, the third meniscus lens 8, and the fourth meniscus lens 9 all have negative curvature radii; the emergent light surfaces of the second meniscus lens 7, the third meniscus lens 8, and the fourth meniscus lens 9 all have negative curvature radii; wherein, the absolute value of the curvature radius of the incident light surface of the third meniscus lens 8 is greater than the absolute value of the curvature radius of the emergent light surface of the third meniscus lens 8; the absolute value of the curvature radius of the emergent light surface of the third meniscus lens 8 is less than the absolute value of the curvature radius of the emergent light surface of the fourth meniscus lens 9; the absolute value of the curvature radius of the incident light surface of the fourth meniscus lens 9 is greater than the absolute value of the curvature radius of the emergent light surface of the fourth meniscus lens 9; the second meniscus lens 7 is used to enhance the beam expansion effect of the laser incident through the fourth negative lens 6; the third meniscus lens 8 and the fourth meniscus lens 9 are used to maintain the light path of the laser incident through the second meniscus lens 7.

[0069] Specifically, the incident light surface of the second meniscus lens 7 is a concave surface with a negative curvature radius, and the emergent light surface is a concave surface with a negative curvature radius, which can enhance the beam expansion effect of the laser emitted from the fourth negative lens 6. Moreover, the incident light surface of the second meniscus lens 7 is a concave surface, and the emergent light surface of the fourth negative lens 6 is a concave surface, so that the second meniscus lens 7 and the fourth negative lens 6 form a symmetric structure similar to the Gaussian structure, which can effectively reduce the spherical aberration of the laser passing through the lens.

[0070] The absolute value of the curvature radius of the incident light surface of the third meniscus lens 8 is greater than the absolute value of the curvature radius of the emergent light surface of the third meniscus lens 8, the absolute value of the curvature radius of the emergent light surface of the third meniscus lens 8 is less than the absolute value of the curvature radius of the emergent light surface of the fourth meniscus lens 9, and the absolute value of the curvature radius of the incident light surface of the fourth meniscus lens 9 is greater than the absolute value of the curvature radius of the emergent light surface of the fourth meniscus lens 9. Exemplarily, the curvature radius of the incident light surface of the second meniscus lens 7 is -230.941 mm, the curvature radius of the emergent light surface of the second meniscus lens 7 is -906.219 mm, the curvature radius of the incident light surface of the third meniscus lens 8 is -141.788 mm, and the curvature radius of the emergent light surface of the third meniscus lens 8 is -117.956 mm, so as to ensure that the light beam further maintains its expanded light path and make the light beam expansion process stable.

[0071] In some alternative embodiments, the distances between adjacent two of the third negative lens 4, the first positive lens 5, the fourth negative lens 6, the second meniscus lens 7, the third meniscus lens 8, the fourth meniscus lens 9, and the second positive lens 10 satisfy:

[0072] d9 < d4 < d5 < d6 < d7 < d8

[0073] Among them, d4 is the distance between the third negative lens 4 and the first positive lens 5, d5 is the distance between the first positive lens 5 and the fourth negative lens 6, d6 is the distance between the fourth negative lens 6 and the second meniscus lens 7, d7 is the distance between the second meniscus lens 7 and the third meniscus lens 8, d8 is the distance between the third meniscus lens 8 and the fourth meniscus lens 9, and d9 is the distance between the fourth meniscus lens 9 and the second positive lens 10.

[0074] Specifically, the value range of the distance d4 between the third negative lens 4 and the first positive lens 5 is: 13.638 mm ≤ d4 ≤ 13.678 mm; the value range of the distance d5 between the first positive lens 5 and the fourth negative lens 6 is: 14.945 mm ≤ d5 ≤ 14.985 mm; the value range of the distance d6 between the fourth negative lens 6 and the second meniscus lens 7 is: 15.93 mm ≤ d6 ≤ 15.97 mm; the value range of the distance d7 between the second meniscus lens 7 and the third meniscus lens 8 is: 15.943 mm ≤ d7 ≤ 15.983 mm; the value range of the distance d8 between the third meniscus lens 8 and the fourth meniscus lens 9 is: 16.992 mm ≤ d8 ≤ 17.032 mm; the value range of the distance d9 between the fourth meniscus lens 9 and the second positive lens 10 is: 12.071 mm ≤ d9 ≤ 12.111 mm.

[0075] When the distances between adjacent two of the third negative lens 4, the first positive lens 5, the fourth negative lens 6, the second meniscus lens 7, the third meniscus lens 8, the fourth meniscus lens 9, and the second positive lens 10 satisfy d9 < d4 < d5 < d6 < d7 < d8, the beam expansion effect of the illumination system based on spherical waves is better, and the expanded beam is stable.

[0076] In some alternative embodiments, the third lens group includes a third positive lens 11 and a second meniscus lens group arranged in sequence along the optical axis direction; the light incident surface of the third positive lens 11 has a positive curvature radius, and its light exiting surface is a plane, which is used for initially converging the laser incident through the second lens group; the second meniscus lens group is used to further enhance the converging effect of the laser incident through the third positive lens 11 and output spherical wave laser in the direction of the holographic mask 15.

[0077] Specifically, the light-emitting surface of the second positive lens 10 is convex, and the light-incident surface of the third positive lens 11 has a positive radius of curvature, so it is convex. That is, the second positive lens 10 and the third positive lens 11 form a mutually symmetric structure similar to the Gauss structure, which can effectively eliminate spherical aberration. The light-emitting surface of the third positive lens 11 is a plane, which can maintain the light trace of the light beam.

[0078] The second meniscus lens group can further enhance the converging effect of the laser, that is, a strong beam convergence ability, thereby improving the numerical aperture of the illumination system and the lithography resolution.

[0079] In some alternative embodiments, the second meniscus lens group includes a fifth meniscus lens 12, a sixth meniscus lens 13, and a seventh meniscus lens 14 arranged in sequence along the optical axis. The light-incident surfaces of the fifth meniscus lens 12, the sixth meniscus lens 13, and the seventh meniscus lens 14 all have positive radii of curvature; the light-emitting surfaces of the fifth meniscus lens 12, the sixth meniscus lens 13, and the seventh meniscus lens 14 all have positive radii of curvature; the absolute values of the radii of curvature of the light-incident surface of the third positive lens 11, the light-incident surface of the fifth meniscus lens 12, the light-incident surface of the sixth meniscus lens 13, and the light-incident surface of the seventh meniscus lens 14 decrease in sequence; the absolute values of the radii of curvature of the light-emitting surface of the third positive lens 11, the light-emitting surface of the fifth meniscus lens 12, the light-emitting surface of the sixth meniscus lens 13, and the light-emitting surface of the seventh meniscus lens 14 decrease in sequence.

[0080] Specifically, the light-incident surfaces of the fifth meniscus lens 12, the sixth meniscus lens 13, and the seventh meniscus lens 14 all have positive radii of curvature, so they are all convex. The light-emitting surfaces of the fifth meniscus lens 12, the sixth meniscus lens 13, and the seventh meniscus lens 14 all have positive radii of curvature, so they are all concave. That is, the fifth meniscus lens 12, the sixth meniscus lens 13, and the seventh meniscus lens 14 all adopt a one-concave-one-convex structure, which can reduce the spherical aberration of the system.

[0081] Let the radius of curvature of the light incident surface of the third positive lens 11 be r111, the radius of curvature of the light exiting surface be r112, the radius of curvature of the light incident surface of the fifth meniscus lens 12 be r121, the radius of curvature of the light exiting surface be r122, the radius of curvature of the light incident surface of the sixth meniscus lens 13 be r131, the radius of curvature of the light exiting surface be r132, the radius of curvature of the light incident surface of the seventh meniscus lens 14 be r141, and the radius of curvature of the light exiting surface be r142. The following relationships are satisfied among the respective radii of curvature: |r111| > |r121| > |r131| > |r141|, |r112| > |r122| > |r132| > |r142|. The converging ability of the lenses closer to the reticle lens increases successively, ensuring that the light beam can converge and form an image at a very short distance to form a 90° angle, with good converging effect, so that the illumination system can obtain a relatively large numerical aperture NA.

[0082] NA is the numerical aperture of the optical system. The numerical aperture is a dimensionless number used to measure the angular range of light that the system can collect. In the illumination system based on spherical waves according to the embodiments of the present invention, a numerical aperture of 0.707 can be obtained through the fifth meniscus lens 12, the sixth meniscus lens 13, and the seventh meniscus lens 14. According to the formula for the numerical aperture:

[0083] NA = n·sinα

[0084] where NA is the numerical aperture of the optical system, and α is half of the imaging angle θ of the light beam. In the embodiments of the present invention, through the fifth meniscus lens 12, the sixth meniscus lens 13, and the seventh meniscus lens 14, the imaging angle is 90°, NA = 0.707, and the system has a relatively large numerical aperture, thereby improving the lithography resolution.

[0085] In some alternative embodiments, the distance between two adjacent lenses among the third positive lens 11, the fifth meniscus lens 12, and the sixth meniscus lens 13 satisfies:

[0086] d11 > d12, and d11 > d13

[0087] where d11 is the distance between the third positive lens 11 and the fifth meniscus lens 12, d12 is the distance between the fifth meniscus lens 12 and the sixth meniscus lens 13, and d13 is the distance between the sixth meniscus lens 13 and the seventh meniscus lens 14.

[0088] Specifically, the distance d11 between the third positive lens 11 and the fifth meniscus lens 12 satisfies: 15.965 mm ≤ d11 ≤ 16.005 mm; the distance d12 between the fifth meniscus lens 12 and the sixth meniscus lens 13 satisfies: 1.605 mm ≤ d12 ≤ 1.645 mm; the distance d13 between the sixth meniscus lens 13 and the seventh meniscus lens 14 satisfies: 1.676 mm ≤ d13 ≤ 1.716 mm.

[0089] When the distances between adjacent two of the third positive lens 11, the fifth meniscus lens 12 and the sixth meniscus lens 13 satisfy: d11 > d12 and d11 > d13, the converging effect can be enhanced to ensure that the system has a large numerical aperture.

[0090] Furthermore, the distance between the second positive lens 10 and the third positive lens 11, the distance between the seventh meniscus lens 14 and the holographic mask 15, and the distance between the holographic mask 15 and the focal plane 16 satisfy:

[0091] d14 > d10 > d15

[0092] wherein, d10 is the distance between the second positive lens 10 and the third positive lens 11, d14 is the distance between the seventh meniscus lens 14 and the holographic mask 15, and d15 is the distance between the holographic mask 15 and the focal plane 16.

[0093] Specifically, for the convenience of subsequent mechanical tooling, the distance d14 between the holographic mask 15 and the seventh meniscus lens 14 is greater than the distance d10 between the second positive lens 10 and the third positive lens 11, which is greater than the distance d15 between the holographic mask 15 and the focal plane 16.

[0094] Specifically, the distance d10 between the second positive lens 10 and the third positive lens 11 satisfies: 13.635 mm ≤ d10 ≤ 15.635 mm; the distance d14 between the seventh meniscus lens 14 and the holographic mask 15 satisfies: 19.000 mm ≤ d14 ≤ 21.000 mm; the distance d15 between the holographic mask 15 and the focal plane 16 satisfies: 8.000 mm ≤ d15 ≤ 10.000 mm.

[0095] For example, the distance d14 between the seventh meniscus lens 14 and the holographic mask 15 is 20 mm, the distance d15 between the holographic mask 15 and the focal plane 16 is 9 mm, and the distance d10 between the second positive lens 10 and the third positive lens 11 is 14.625 mm. When d14 > d10 > d15, the distance between the seventh meniscus lens 14 and the holographic mask 15 is relatively large because here, i.e., the distance between the last lens and the holographic mask 15 needs to be large enough to leave space for the mechanical structure to replace the holographic mask 15.

[0096] In some alternative embodiments, a diaphragm is provided between the second lens group and the third lens group. By providing the diaphragm, stray light interference can be avoided, and the light beam emitted from the second lens group can be constrained.

[0097] In some alternative embodiments, the first lens group includes a first negative lens 1 and a first meniscus lens 2 arranged in sequence along the optical axis direction. A second negative lens 3 is provided between the first lens group and the second lens group. The second lens group includes a third negative lens 4, a first positive lens 5, a fourth negative lens 6, a second meniscus lens 7, a third meniscus lens 8, a fourth meniscus lens 9, and a second positive lens 10 arranged in sequence along the optical axis direction. The third lens group includes a third positive lens 11, a fifth meniscus lens 12, a sixth meniscus lens 13, and a seventh meniscus lens 14 arranged in sequence along the optical axis direction. The centers of the first negative lens 1, the first meniscus lens 2, the second negative lens 3, the third negative lens 4, the first positive lens 5, the fourth negative lens 6, the second meniscus lens 7, the third meniscus lens 8, the fourth meniscus lens 9, the second positive lens 10, the third positive lens 11, the fifth meniscus lens 12, the sixth meniscus lens 13, and the seventh meniscus lens 14 are all disposed on the optical axis. The lens material is all made of ultraviolet fused silica and the lenses are all spherical mirrors.

[0098] The working principle of the illumination system based on spherical waves according to the embodiments of the present invention is as follows: The light beam is incident in front of the first lens group, and after being refracted by the second lens group, the field of view fills the diaphragm between the second positive lens 10 and the third positive lens 11, and then is refracted and focused by the third lens group. After passing through the seventh meniscus lens 14, it diffracts at the holographic mask 15, thereby generating an image on the focal plane 16. The holographic mask 15 is a holographic mask manufactured by calculating through the holographic algorithm for spherical waves. The second lens group plays a role in beam expansion, and the third lens group is for focusing. In the entire lens group, since the positive lens provides positive spherical aberration and the negative lens provides negative spherical aberration, the second lens group and the third lens group comprehensively use positive lenses, negative lenses, and meniscus lenses, which can effectively reduce the spherical aberration of the system, and the sixth meniscus lens 13 and the seventh meniscus lens 14 can focus the light beam and obtain a large numerical aperture.

[0099] Specifically, the selected combination of the first negative lens 1, the first meniscus lens 2, the second negative lens 3, the third negative lens 4, the first positive lens 5, the fourth negative lens 6, the second meniscus lens 7, the third meniscus lens 8, the fourth meniscus lens 9, the second positive lens 10, the third positive lens 11, the fifth meniscus lens 12, the sixth meniscus lens 13, and the seventh meniscus lens 14 has a relatively small overall spherical aberration. Therefore, aspherical lenses and cemented lenses for reducing spherical aberration are not required for the lens, and only spherical lenses are needed. Compared with aspherical lenses and cemented lenses, spherical lenses have a simple structure and are convenient to process.

[0100] In the embodiment of the present invention, two evaluation methods are adopted to evaluate the illumination system based on spherical waves.

[0101] Specifically, for the first negative lens 1, the first meniscus lens 2, the second negative lens 3, the third negative lens 4, the first positive lens 5, the fourth negative lens 6, the second meniscus lens 7, the third meniscus lens 8, the fourth meniscus lens 9, the second positive lens 10, the third positive lens 11, the fifth meniscus lens 12, the sixth meniscus lens 13, and the seventh meniscus lens 14 of the illumination system based on spherical waves to be evaluated, all are made of ultraviolet fused silica. The holographic lithography illumination system operates in an environment filled with nitrogen. The refractive index of ultraviolet fused silica under nitrogen is 1.560737. The light source is a 193nm ArF laser. The radius of curvature, thickness, and spacing of each lens of the illumination system based on spherical waves are shown in the following table:

[0102]

[0103]

[0104] In the above table, STO represents the aperture stop, and the corresponding spacing represents the spacing between the aperture stop and the third positive lens 11. MASK represents the holographic mask 15, and the corresponding spacing represents the thickness of the holographic mask 15. The spacing corresponding to the 31st surface represents the spacing between the rear surface of the holographic mask 15 and the distance focal plane 16. The spacings corresponding to the remaining surfaces respectively represent the middle thickness of each lens and the spacing between two adjacent lenses among the first negative lens 1, the first meniscus lens 2, the second negative lens 3, the third negative lens 4, the first positive lens 5, the fourth negative lens 6, the second meniscus lens 7, the third meniscus lens 8, the fourth meniscus lens 9, the second positive lens 10, the third positive lens 11, the fifth meniscus lens 12, the sixth meniscus lens 13, and the seventh meniscus lens 14 arranged in sequence, that is:

[0105] The radius of curvature of the front surface of the first negative lens 1 is -83.573mm, the radius of curvature of the rear surface of the first negative lens 1 is 31.199mm, the thickness of the first negative lens 1 is 13.549mm, and the spacing between the first negative lens 1 and the first meniscus lens 2 is 11.945mm;

[0106] The radius of curvature of the front surface of the first meniscus lens 2 is 65.36 mm, the radius of curvature of the rear surface of the first meniscus lens 2 is 8.946 mm, the thickness of the first meniscus lens 2 is 13.021 mm, and the distance between the first meniscus lens 2 and the second negative lens 3 is 11.669 mm;

[0107] The radius of curvature of the front surface of the second negative lens 3 is -22.261 mm, the radius of curvature of the rear surface of the second negative lens 3 is 626.593 mm, the thickness of the second negative lens 3 is 21.056 mm, and the distance between the second negative lens 3 and the third negative lens 4 is 18.629 mm;

[0108] The radius of curvature of the front surface of the third negative lens 4 is -463.196 mm, the radius of curvature of the rear surface of the third negative lens 4 is 311.436 mm, the thickness of the third negative lens 4 is 19.991 mm, and the distance between the third negative lens 4 and the first positive lens 5 is 13.658 mm;

[0109] The radius of curvature of the front surface of the first positive lens 5 is 800 mm, the rear surface of the first positive lens 5 is a plane, the thickness of the first positive lens 5 is 11 mm, and the distance between the first positive lens 5 and the fourth negative lens 6 is 14.965 mm;

[0110] The front surface of the fourth negative lens 6 is a plane, the radius of curvature of the rear surface of the fourth negative lens 6 is 108.189 mm, the thickness of the fourth negative lens 6 is 14.051 mm, and the distance between the fourth negative lens 6 and the second meniscus lens 7 is 15.95 mm;

[0111] The radius of curvature of the front surface of the second meniscus lens 7 is -230.941 mm, the radius of curvature of the rear surface of the second meniscus lens 7 is -906.219 mm, the thickness of the second meniscus lens 7 is 17.917 mm, and the distance between the second meniscus lens 7 and the third meniscus lens 8 is 15.963 mm;

[0112] The radius of curvature of the front surface of the third meniscus lens 8 is -141.788 mm, the radius of curvature of the rear surface of the third meniscus lens 8 is -117.956 mm, the thickness of the third meniscus lens 8 is 25.025 mm, and the distance between the third meniscus lens 8 and the fourth meniscus lens 9 is 17.012 mm;

[0113] The radius of curvature of the front surface of the fourth meniscus lens 9 is -260.929 mm, the radius of curvature of the rear surface of the fourth meniscus lens 9 is -195.966 mm, the thickness of the fourth meniscus lens 9 is 23.025 mm, and the distance between the fourth meniscus lens 9 and the second positive lens 10 is 12.091 mm;

[0114] The radius of curvature of the front surface of the second positive lens 10 is 1265.636 mm, the radius of curvature of the rear surface of the second positive lens 10 is -195.965 mm, the thickness of the second positive lens 10 is 21.269 mm, and the distance between the second positive lens 10 and the diaphragm is 7 mm;

[0115] The radius of curvature of the front surface of the third positive lens 11 is 201.953 mm, the rear surface of the third positive lens 11 is a plane, the thickness of the third positive lens 11 is 22.026 mm, and the distance between the third positive lens 11 and the fifth meniscus lens is 15.985 mm;

[0116] The radius of curvature of the front surface of the fifth meniscus lens 12 is 117.696 mm, the radius of curvature of the rear surface of the fifth meniscus lens 12 is 232.096 mm, the thickness of the fifth meniscus lens 12 is 25.004, and the distance between the fifth meniscus lens 12 and the sixth meniscus lens 13 is 1.625 mm;

[0117] The radius of curvature of the front surface of the sixth meniscus lens 13 is 66.01 mm, the radius of curvature of the rear surface of the sixth meniscus lens 13 is 109.017 mm, the thickness of the sixth meniscus lens 13 is 25.104 mm, and the distance between the sixth meniscus lens 13 and the seventh meniscus lens 14 is 1.696 mm;

[0118] The radius of curvature of the front surface of the seventh meniscus lens 14 is 49.57 mm, the radius of curvature of the rear surface of the seventh meniscus lens 14 is 50.567 mm, the thickness of the seventh meniscus lens 14 is 25.036 mm, and the distance between the seventh meniscus lens 14 and the holographic mask 15 is 20 mm.

[0119] The two evaluation methods and their evaluation results are as follows:

[0120] 1. Evaluation of optical modulation transfer function (MTF)

[0121] The optical modulation transfer function is a direct evaluation of the resolution of an optical system. In the embodiment of the present invention, the MTF of the illumination system based on spherical waves has basically reached the diffraction limit. As Figure 4 shown, the optical modulation transfer function (OTF is the optical transfer function, and the modulus of the optical transfer function OTF is the MTF) obtained by the optical software Zemax shows that for the illumination system based on spherical waves in this example, when the MTF ≈ 40% in the full field of view, the system resolution reaches 3500 lp / mm. The cut-off frequency reaches 7100 lp / mm.

[0122] 2. Evaluation of root mean square wave aberration

[0123] As Figure 5 、 Figure 6 and Figure 7As shown, the root mean square wave aberration is shown in units of a wavelength λ equal to 193.368 nm. For the spherical wave-based illumination system according to an embodiment of the present invention, with the central ray as a reference, the minimum value of the root mean square wave aberration in the 0.00° field of view is 0.367 nm.

[0124] The minimum value of the root mean square wave aberration in the 0.05° field of view is 0.58 nm.

[0125] The minimum value of the root mean square wave aberration in the 0.1° field of view is 0.986 nm.

[0126] As can be seen from the above, in the three set fields of view, the values of the root mean square wave aberration of the spherical wave-based illumination system according to the embodiment of the present invention are relatively low, having a relatively good effect. The reduction of the wave aberration can improve the lithography resolution.

[0127] The spherical wave-based illumination system according to an embodiment of the present invention has the following advantages:

[0128] 1. It is composed of only 14 lenses, with a simple and compact structure, which simplifies the manufacturing process and reduces the manufacturing cost.

[0129] 2. The numerical aperture NA of the holographic lithography illumination system is 0.707, and the working wavelength is 193 nm. With a large numerical aperture, the lithography resolution is significantly improved due to the large numerical aperture.

[0130] 3. The imaging quality is excellent, and the root mean square wave aberration with reference to the central ray is less than 0.4 nm.

[0131] 4. The compensation mechanism has a simple structure, and the compensation adjustment for the thickness tolerance of the holographic mask 15 can be achieved through one compensation mechanism;

[0132] 5. It is composed of an extremely simple lens assembly, which can not only achieve the progressive beam expansion of the light beam, but also achieve the progressive beam convergence of the light beam. Thus, with the cooperation of the aperture stop, the stable output of the spherical wave can be achieved, and the precise incidence on the mask can be realized, thereby greatly ensuring the exposure yield.

[0133] In summary, compared with the traditional lithography technology, the spherical wave-based illumination system according to the embodiment of the present invention improves the integration degree of the system and reduces the cost of the lithography process.

[0134] An embodiment of the present invention further provides an exposure device, which is applied to the chip preparation process. The silicon wafer is subjected to an exposure process through this exposure device, and this exposure device includes the spherical wave-based illumination system in the above embodiment.

[0135] For the specific implementation manner and beneficial effects of this exposure device, reference can be made to the spherical wave-based illumination system in the above embodiment, and details will not be described herein again.

[0136] Although the embodiments of the present invention have been described above in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A spherical wave-based illumination system, applied to holographic lithography, characterized in that It includes a first lens group, a second lens group, and a third lens group arranged in sequence along the optical axis direction; The first lens group is used to receive the input laser; The second lens group is used to expand the received laser; The third lens group is used to converge the expanded laser and output spherical wave laser in the direction of the holographic mask plate (15); A second negative lens (3) arranged along the optical axis between the first lens group and the second lens group; The light incident surface of the second negative lens (3) has a negative curvature radius, and its light output surface has a positive curvature radius; wherein, the absolute value of the curvature radius of the light output surface of the second negative lens (3) is greater than 600 mm; A compensation mechanism, the compensation mechanism is connected to the second negative lens (3), the compensation mechanism is used to drive the second negative lens (3) to move along the optical axis between the first lens group and the second lens group, and realize optical path compensation by adjusting the position of the second negative lens (3) on the optical axis. The moving range Δl of the second negative lens (3) satisfies with reference to the starting position of the second negative lens (3): -1.5 mm ≤ Δl ≤ +1.5 mm.

2. The illumination system based on spherical waves according to claim 1, characterized in that The first lens group includes a first negative lens (1) and a first meniscus lens (2) arranged in sequence along the optical axis direction; The light incident surface of the first negative lens (1) has a negative curvature radius, and its light output surface has a positive curvature radius, which is used to receive the input laser and perform preliminary beam expansion; The light incident surface of the first meniscus lens (2) has a positive curvature radius, and its light output surface has a positive curvature radius, which is used to further expand the laser beam that has undergone preliminary beam expansion; Wherein, the absolute value of the curvature radius of the light output surface of the first meniscus lens (2) is less than the absolute value of the curvature radius of the light incident surface of the first meniscus lens (2), and the beam expansion ability of the first meniscus lens (2) is stronger than that of the first negative lens (1).

3. The illumination system based on spherical waves according to claim 2, characterized in that, The distance d1 between the first negative lens (1) and the first meniscus lens (2) satisfies: 11.925 mm ≤ d1 ≤ 11.965 mm.

4. The illumination system based on spherical waves according to claim 1, wherein The second lens group includes a third negative lens (4), a first positive lens (5), a fourth negative lens (6), a first meniscus lens group, and a second positive lens (10) arranged in sequence along the optical axis direction; The light incident surface of the third negative lens (4) has a negative curvature radius, and its light output surface has a positive curvature radius, which is used to expand the light beam incident by the first lens group; The light incident surface of the first positive lens (5) has a positive curvature radius, and its light output surface is a plane, which is used to converge the laser incident by the third negative lens (4) to limit the beam expansion effect of the third negative lens (4); The light incident surface of the fourth negative lens (6) is a plane, and its light output surface has a positive curvature radius, which is used to enhance the beam expansion of the laser incident by the first positive lens (5); The first meniscus lens group is used to enhance the beam expansion effect of the laser incident by the fourth negative lens (6) and maintain the light path of the laser in the propagation path; The light incident surface of the second positive lens (10) has a positive radius of curvature, and its light exit surface has a negative radius of curvature, which is used to convert the laser incident through the first meniscus lens group into a quasi-collimated beam.

5. The illumination system based on spherical waves according to claim 4, characterized in that, The first meniscus lens group includes a second meniscus lens (7), a third meniscus lens (8), and a fourth meniscus lens (9) sequentially arranged along the optical axis direction; The light incident surfaces of the second meniscus lens (7), the third meniscus lens (8), and the fourth meniscus lens (9) all have negative radii of curvature; The light exit surfaces of the second meniscus lens (7), the third meniscus lens (8), and the fourth meniscus lens (9) all have negative radii of curvature; Among them, the absolute value of the radius of curvature of the light incident surface of the third meniscus lens (8) is greater than the absolute value of the radius of curvature of its light exit surface; the absolute value of the radius of curvature of the light exit surface of the third meniscus lens (8) is less than the absolute value of the radius of curvature of the light exit surface of the fourth meniscus lens (9); the absolute value of the radius of curvature of the light incident surface of the fourth meniscus lens (9) is greater than the absolute value of the radius of curvature of its light exit surface; The second meniscus lens (7) is used to enhance the beam expansion effect of the laser incident through the fourth negative lens (6); The third meniscus lens (8) and the fourth meniscus lens (9) are used to maintain the light path of the laser incident through the second meniscus lens (7).

6. The illumination system based on spherical waves according to claim 5, characterized in that, The distances between adjacent two of the third negative lens (4), the first positive lens (5), the fourth negative lens (6), the second meniscus lens (7), the third meniscus lens (8), the fourth meniscus lens (9), and the second positive lens (10) satisfy: d9 < d4 < d5 < d6 < d7 < d8 Wherein, d4 is the distance between the third negative lens (4) and the first positive lens (5), d5 is the distance between the first positive lens (5) and the fourth negative lens (6), d6 is the distance between the fourth negative lens (6) and the second meniscus lens (7), d7 is the distance between the second meniscus lens (7) and the third meniscus lens (8), d8 is the distance between the third meniscus lens (8) and the fourth meniscus lens (9), and d9 is the distance between the fourth meniscus lens (9) and the second positive lens (10).

7. The illumination system based on spherical waves according to claim 6, characterized in that, The third lens group includes a third positive lens (11) and a second meniscus lens group sequentially arranged along the optical axis direction; The light incident surface of the third positive lens (11) has a positive radius of curvature, and its light exit surface is a plane, which is used to preliminarily converge the laser incident through the second lens group; The second meniscus lens group is used to further enhance the converging effect of the laser incident through the third positive lens (11) and output spherical wave laser towards the holographic mask plate (15).

8. The illumination system based on spherical waves according to claim 7, wherein, The second meniscus lens group includes a fifth meniscus lens (12), a sixth meniscus lens (13), and a seventh meniscus lens (14) sequentially arranged along the optical axis direction; The light incident surfaces of the fifth meniscus lens (12), the sixth meniscus lens (13), and the seventh meniscus lens (14) all have positive curvature radii; The light exiting surfaces of the fifth meniscus lens (12), the sixth meniscus lens (13), and the seventh meniscus lens (14) all have positive curvature radii; The absolute values of the curvature radii of the light incident surfaces of the third positive lens (11), the fifth meniscus lens (12), the sixth meniscus lens (13), and the seventh meniscus lens (14) decrease in sequence; The absolute values of the curvature radii of the light exiting surfaces of the third positive lens (11), the fifth meniscus lens (12), the sixth meniscus lens (13), and the seventh meniscus lens (14) decrease in sequence.

9. The illumination system based on spherical waves according to claim 8, characterized in that The spacing between adjacent two of the third positive lens (11), the fifth meniscus lens (12), and the sixth meniscus lens (13) satisfies: d11 > d12, and d11 > d13 wherein, d11 is the spacing between the third positive lens (11) and the fifth meniscus lens (12), d12 is the spacing between the fifth meniscus lens (12) and the sixth meniscus lens (13), and d13 is the spacing between the sixth meniscus lens (13) and the seventh meniscus lens (14).

10. The illumination system based on spherical waves according to claim 9, wherein, The spacing between the second positive lens (10) and the third positive lens (11), the spacing between the seventh meniscus lens (14) and the holographic mask plate (15), and the spacing between the holographic mask plate (15) and the focal plane (16) satisfy: d14 > d10 > d15 wherein, d10 is the spacing between the second positive lens (10) and the third positive lens (11), d14 is the spacing between the seventh meniscus lens (14) and the holographic mask plate (15), and d15 is the spacing between the holographic mask plate (15) and the focal plane (16).

11. The illumination system based on spherical waves according to claim 1, characterized in that, A diaphragm is provided between the second lens group and the third lens group.

12. An exposure device, applied to a chip manufacturing process, characterized in that The exposure apparatus includes a spherical-wave-based illumination system according to any one of claims 1 to 11.

Images