Illuminating system based on spherical waves and exposure equipment

Abstract

The invention discloses a spherical wave-based illumination system and exposure equipment, which are applied to the technical field of holographic lithography, and the holographic lithography illumination system comprises a first lens group, a second lens group and a third lens group which are sequentially arranged along the direction of an optical axis, the first lens group is used for receiving input laser; the second lens group is used for expanding the received laser; and the third lens group is used for collecting the expanded laser and outputting spherical wave laser to the direction of the holographic mask. According to the invention, under the condition that only three lens groups are matched, the resolution of photoetching imaging through the holographic mask plate is greatly improved, so that the exposure yield is ensured, and compared with the traditional projection photoetching, the number of used lenses can be greatly reduced, and the manufacturing cost is greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of holographic lithography, and in particular to an illumination system and exposure equipment based on spherical waves. Background Art

[0002] Photolithography is an integrated circuit manufacturing technology and a key process in the production and manufacturing of large-scale integrated circuits. It is a technology that uses lasers to image mask patterns onto silicon wafers. Since the 1960s, the structural forms of photolithography machines have gone through the development stages of contact, proximity, scanning projection, distributed projection and step-and-scan projection photolithography machines. The traditional projection photolithography system uses the principle of optical projection imaging to project the pattern on the mask onto the substrate for exposure by using lenses or reflectors. The optical path in this technology is complex, the cost is high, and the volume is large. The optical materials available for deep ultraviolet light in the 193nm band are single, and the production is difficult. Additional projection objectives are required to form a complex optical system. The integrated circuit threads that can be processed by the traditional projection exposure photolithography method are limited by the projection objective. In the field of traditional projection photolithography, the projection photolithography objective with an operating wavelength of 193nm is the core component of the projection photolithography device for producing ultra-fine patterns. At present, the projection photolithography objective has a complex structure, is difficult to manufacture, and is expensive. Most systems with a numerical aperture of 0.7 have high-order aspheric surfaces, long conjugate distances, and large system volumes. For example, patent US20030030916A1 introduces a projection lithography objective lens with a maximum numerical aperture of 0.89, which includes at least 4 groups of lenses, a total of 29 lenses, each group of lenses has either positive or negative focal 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, it is necessary to simplify the number of lenses, and the low-cost, highly integrated new lithography technology will promote the development of lithography and semiconductor fields. Summary of the invention

[0003] In view of this, the present invention provides an illumination system and exposure equipment based on spherical waves, which can overcome the technical problems of a large number of lenses and a complex structure in the prior art photolithography illumination system.

[0004] A first aspect of the present invention provides an illumination system based on spherical waves, which is applied to holographic lithography, and includes a first lens group, a second lens group, and a third lens group, which are arranged in sequence along the optical axis; the first lens group is used to receive input laser light; the second lens group is used to expand the received laser light; the third lens group is used to converge the expanded laser light and output spherical wave laser light 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; the light entrance surface of the first negative lens has a negative curvature radius, and the light exit surface thereof has a positive curvature radius, for receiving input laser light and performing preliminary beam expansion; the light entrance surface of the first meniscus lens has a positive curvature radius, and the light exit surface thereof has a positive curvature radius, for further expanding the laser light that has undergone preliminary beam expansion; wherein the absolute value of the curvature radius of the light exit surface of the first meniscus lens is smaller than the absolute value of the curvature radius of the light entrance surface of the first meniscus lens, and the beam expansion capability of the first meniscus lens is stronger than that of the first negative lens.

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

[0007] Optionally, the spherical wave-based illumination system further comprises a second negative lens disposed between the first lens group and the second lens group along the optical axis; a light-entry surface of the second negative lens has a negative radius of curvature, and a light-exit surface thereof has a positive radius of curvature; wherein an absolute value of the radius of curvature of the light-exit surface of the second negative lens is greater than 600 mm.

[0008] Optionally, the spherical wave-based illumination system further includes a compensation mechanism, which is connected to the second negative lens, and 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 to achieve optical path compensation by adjusting the position of the second negative lens on the optical axis, and a moving range Δl of the second negative lens satisfies the following with reference to a starting position of the second negative lens: -1.5mm≤Δl≤+1.5mm.

[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, which are arranged in sequence along the optical axis; the light entrance surface of the third negative lens has a negative curvature radius, and the light exit surface thereof has a positive curvature radius, and is used to expand the light beam incident through the first lens group; the light entrance surface of the first positive lens has a positive curvature radius, and the light exit surface thereof is a plane, and is used to converge the laser incident through the third negative lens to limit the beam expansion effect of the third negative lens; the light entrance surface of the fourth negative lens is a plane, and the light exit surface thereof has a positive curvature radius, and 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 to maintain the light track of the laser in the propagation path; the light entrance surface of the second positive lens has a positive curvature radius, and the light exit surface thereof has a negative curvature radius, and 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 light-entering surface of the second meniscus lens, the light-entering surface of the third meniscus lens and the light-entering surface of the fourth meniscus lens all have a negative curvature radius; the light-emitting surface of the second meniscus lens, the light-emitting surface of the third meniscus lens and the light-emitting surface of the fourth meniscus lens all have a negative curvature radius; wherein the absolute value of the curvature radius of the light-entering surface of the third meniscus lens is greater than that of the third meniscus lens the absolute value of the radius of curvature of the light emitting surface of the third meniscus lens is smaller than the absolute value of the radius of curvature of the light emitting surface of the fourth meniscus lens; the absolute value of the radius of curvature of the light incident surface of the fourth meniscus lens is larger than the absolute value of the radius of curvature of the light emitting surface of the fourth meniscus lens; the second meniscus lens is used to enhance the beam expanding 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 track of the laser incident through the second meniscus lens.

[0011] Optionally, a distance between two adjacent lenses among 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 satisfies:

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

[0013] Among them, 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; the light incident surface of the third positive lens has a positive curvature radius, and the light exit surface thereof is a plane, and is used to initially 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 in the direction of the holographic mask.

[0015] Optionally, the second meniscus lens group includes a fifth meniscus lens, a sixth meniscus lens and a seventh meniscus lens which are arranged in sequence along the optical axis; the light-entering surface of the fifth meniscus lens, the light-entering surface of the sixth meniscus lens and the light-entering surface of the seventh meniscus lens all have a positive curvature radius; the light-exiting surface of the fifth meniscus lens, the light-exiting surface of the sixth meniscus lens and the light-exiting surface of the seventh meniscus lens all have a positive curvature radius; the absolute value of the radius of curvature of the light-entering surface of the third positive lens, the absolute value of the radius of curvature of the light-entering surface of the fifth meniscus lens, the absolute value of the radius of curvature of the light-entering surface of the sixth meniscus lens and the absolute value of the radius of curvature of the light-entering surface of the seventh meniscus lens decrease in sequence; the absolute value of the radius of curvature of the light-exiting surface of the third positive lens, the absolute value of the radius of curvature of the light-exiting surface of the fifth meniscus lens, the absolute value of the radius of curvature of the light-exiting surface of the sixth meniscus lens and the absolute value of the radius of curvature of the light-exiting surface of the seventh meniscus lens decrease in sequence.

[0016] Optionally, the distance between two adjacent lenses among the third positive lens, the fifth meniscus lens and the sixth meniscus lens satisfies:

[0017] d11>d12, and d11>d13

[0018] Among them, 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 distance between the second positive lens and the third positive lens, the distance between the seventh meniscus lens and the holographic mask, and the distance between the holographic mask 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, and d15 is the distance between the holographic mask and the focal plane.

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

[0023] A second aspect of the present invention provides an exposure device for use in a chip manufacturing process, wherein the exposure device comprises the spherical wave-based illumination system as described in any one of the first aspects.

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

[0025] The spherical wave-based illumination system and exposure equipment of the present invention receive the laser light emitted by the light source through the first lens group, and then expand the received laser light through the second lens group, so that the expansion process can be more stable and progressive expansion can be achieved. The expanded laser light is converged by the third lens group, and the light beam propagates in the direction of the holographic mask in the form of a spherical wave. The light beam is diffracted after passing through the holographic mask to produce an image on the focal plane, that is, an image is formed on the silicon wafer. The convergence of the third lens group can enable the holographic lithography illumination system to obtain a larger numerical aperture. When only three lens groups are used, 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, thereby greatly reducing the manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 Schematic diagram of the light path of the spherical wave-based illumination system according to an embodiment of the present invention;

[0028] Figure 2 is a schematic structural diagram of a spherical wave-based lighting system according to an embodiment of the present invention;

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

[0030] Figure 4 is a schematic diagram of an optical modulation transfer function of a spherical wave-based illumination system according to an embodiment of the present invention;

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

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

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

[0034] Description of reference numerals:

[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 DESCRIPTION

[0036] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "front", "rear", "left", "right", etc. are based on the directions or positional relationships shown in the drawings, and are 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 direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0038] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" 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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] In addition, the technical features involved in the 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] Holographic lithography system is a technology that uses laser to image the pattern on the holographic mask onto a substrate such as a silicon wafer, which can be used in the manufacture of integrated circuits. Compared with projection lithography, holographic lithography has lower requirements on the process of the illumination system. There is no object-image relationship between the mask and the silicon wafer, which can avoid the dependence of conventional projection lithography on the projection objective lens. In the holographic lithography system, the performance of the holographic lithography illumination system is the key to holographic lithography technology, which directly determines the graphic transmission capability of the entire exposure device.

[0041] In the field of holographic lithography, the main work is to improve the calculation of holographic masks. Currently, there is no lighting system designed based on the characteristics of holographic lithography. Instead, the light source is directly used to illuminate the holographic mask for projection, which has poor imaging effect. The use of projection lithography objective lenses causes structural redundancy. Therefore, there is an urgent need for an illumination system with a simple structure that meets the requirements of holographic lithography.

[0042] At present, the illumination system of the holographic lithography system is divided into a spherical wave-based illumination system and a plane wave-based illumination system. The spherical wave-based illumination system requires that the laser output by the light source be propagated to the mask in the form of a spherical wave, and requires a larger numerical aperture of the illumination system to improve the lithography resolution.

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

[0044] Specifically, the function of the first lens group is to receive laser light, so that the laser light entering the lighting system enters smoothly, stabilizes the light beam, and realizes progressive beam expansion. Therefore, the first lens group uses a lens with a larger absolute value of the radius of curvature to stabilize the light beam.

[0045] The second lens group includes multiple lenses, which are mainly formed by one or more combinations of positive lenses, negative lenses or meniscus lenses. The second lens group has a total negative optical focal length, so that the second lens group can further progressively expand the laser output by the light source.

[0046] The third lens group includes multiple lenses, mainly formed by one or more combinations of positive lenses, negative lenses or meniscus lenses. The second lens group has a total negative focal length, so that the second lens group can expand the laser output by the light source. Since the second lens group has a total negative focal length and the third lens group has a total positive focal length, the spherical aberrations generated by the two are opposite, which will produce a partial offset, thereby reducing the total spherical aberration of the lighting system and ensuring that it can be gradually and stably converged.

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

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

[0049] A spherical wave-based illumination system according to an embodiment of the present invention receives laser light emitted by a light source through a first lens group, and then expands the received laser light through a second lens group, so that the expansion process can be smoother and progressive expansion can be achieved. The expanded laser light is converged through a third lens group, and the light beam propagates in the direction of the holographic mask in the form of a spherical wave. The light beam diffracts after passing through the holographic mask, and an image is generated on a focal plane 16, that is, an image is formed on a silicon wafer. The progressive and stable convergence of the third lens group enables the holographic lithography illumination system to obtain a larger numerical aperture, thereby greatly improving the resolution of lithography imaging through the holographic mask when only three lens groups are used, thereby ensuring the exposure yield. Compared with traditional projection lithography, the number of lenses used can be greatly reduced, thereby greatly reducing the manufacturing cost.

[0050] In some optional embodiments, the first lens group includes a first negative lens 1 and a first meniscus lens 2 which are arranged in sequence along the optical axis; the light-entry surface of the first negative lens 1 has a negative curvature radius, and the light-exit surface thereof has a positive curvature radius, for receiving input laser light and performing preliminary beam expansion; the light-entry surface of the first meniscus lens 2 has a positive curvature radius, and the light-exit surface thereof has a positive curvature radius, for further expanding the laser light after preliminary beam expansion; wherein the absolute value of the curvature radius of the light-exit surface of the first meniscus lens 2 is smaller than the absolute value of the curvature radius of the light-entry surface of the first meniscus lens 2, and the beam expansion capability of the first meniscus lens 2 is stronger than that of the first negative lens 1.

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

[0052] The light-entry surface of the first negative lens 1, i.e. the front surface, is a concave surface with a negative curvature radius, which is used to receive the laser beam. After the beam is refracted on this surface, it will undergo preliminary beam expansion. The light-exit surface of the first negative lens 1, i.e. the rear surface, is a concave surface with a positive curvature radius, which is used for refracting and expanding the beam.

[0053] The light-entering surface, i.e., the front surface, of the first meniscus lens 2 is a convex surface with a positive radius of curvature, where the light beam will be converged after being refracted, i.e., the expansion of the light beam will be temporarily suspended. The light-exiting surface of the first meniscus lens 2 is a concave surface with a positive radius of curvature, which is used to further expand the light beam, and the absolute value of the curvature radius at this time is relatively small, i.e., the absolute value of the curvature radius of the light-exiting surface of the first meniscus lens 2 is at least smaller than the absolute value of the curvature radius of the light-entering surface of the first meniscus lens 2.

[0054] Specifically, the range of the curvature radius r11 of the front surface of the first negative lens 1 is: -83.591mm≤r11≤-83.551mm, the range of the curvature radius r12 of the rear surface of the first negative lens 1 is: 31.171mm≤r12≤31.211mm, the range of the curvature radius r21 of the front surface of the first meniscus lens 2 is: 65.16mm≤r21≤65.56mm, the range of the curvature radius r22 of the rear surface of the first meniscus lens 2 is: 8.926mm≤r22≤8.966mm, and the absolute value of the curvature radius of the light-emitting surface of the first meniscus lens 2 is small, so that it has a strong beam expansion ability, and the beam expansion ability of the first meniscus lens 2 is stronger than that of the first negative lens 1, so as to achieve smooth reception and expansion of the light beam. In addition, the first meniscus lens 2 adopts a concave and a convex combination, which will make the curvature radii cancel each other, thereby eliminating the spherical aberration on the axis.

[0055] In some optional implementations, 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 distance d1 between the first negative lens 1 and the first meniscus lens 2 is in the range of 11.925 mm≤d1≤11.965 mm, a stable light beam can be achieved, and the effect of progressive beam expansion can be realized.

[0057] In some optional embodiments, the spherical wave based illumination system further comprises a second negative lens 3 arranged between the first lens group and the second lens group along the optical axis; the light incident surface of the second negative lens 3 has a negative radius of curvature, and the light emitting surface thereof 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 exit surface of the second negative lens 3 is a concave surface with a positive radius of curvature, which can achieve further expansion. Moreover, since the absolute value of its radius of curvature is greater than 600 mm, illustratively, its radius of curvature is 626.593 mm, its expansion capability is relatively weak, and the original expanded light path of the light beam is maintained.

[0059] In some optional embodiments, the spherical wave based illumination system further comprises a compensation mechanism, wherein the compensation mechanism is connected to the second negative lens 3, and the compensation mechanism is connected to the second negative lens 3, and 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 optical path compensation is achieved by adjusting the position of the second negative lens 3 on the optical axis, and the moving range of the second negative lens 3 satisfies the following with reference to the starting position of the second negative lens 3: -1.5mm≤Δl≤+1.5mm, wherein Δl represents the moving range.

[0060] Specifically, the compensation mechanism adopts a mechanical translation micro-motion stage carrying the second lens, or a micro-motor connected to the second lens via an output shaft. The mechanical translation micro-motion stage or micro-motor drives the second negative lens 3 to move along the optical axis to adjust the position of the second negative lens 3 on the optical axis.

[0061] During the photolithography process, the holographic mask 15 will be replaced, and 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 along the front-back direction of the optical axis by the compensation mechanism, so as to compensate for the thickness tolerance of the holographic mask 15. The stroke of the compensation mechanism is ±1.5mm, and the accuracy is 0.1μm, so that the movement range of the second negative lens 3 satisfies the following conditions with reference to the starting position of the second negative lens 3: -1.5mm≤Δl≤+1.5mm. Therefore, the spacing between the second negative lens 3 and the first lens group and the spacing between the second negative lens 3 and the second lens group can be adjusted within this range, so as to achieve compensation for the thickness tolerance of the holographic mask 15.

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

[0063] Specifically, the light-entry surface of the third negative lens 4 is a concave surface with a negative curvature radius and a large absolute value of the curvature radius, and the absolute value of the curvature radius 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 curvature radius and a large curvature radius, and the absolute value of the curvature radius is greater than 300 mm, which is used to continue to expand the expanded beam. By adopting a curvature radius with a large absolute value, the light track of the expanded laser can be maintained.

[0064] The light-entry surface of the first positive lens 5 is a convex surface with a positive curvature radius and a large absolute value of the curvature radius, and the absolute value of the curvature radius is greater than 780 mm, which is used to receive the outgoing light beam 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 trace of the expanded light beam.

[0065] The light-entering surface of the fourth negative lens 6 is a plane, and the curvature radius of the plane is infinite. The light-exiting surface of the fourth negative lens 6 is a concave surface with a positive curvature radius, which is used to further expand the light beam. The expansion effect is first reduced by the first positive lens 5, and then enhanced by the fourth negative lens 6, so that the expansion process can be carried out smoothly, and the light beam is more stable during the expansion process.

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

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

[0068] Furthermore, the first meniscus lens group comprises a second meniscus lens 7, a third meniscus lens 8 and a fourth meniscus lens 9 which are sequentially arranged along the optical axis direction, and the light-entering surface of the second meniscus lens 7, the light-entering surface of the third meniscus lens 8 and the light-entering surface of the fourth meniscus lens 9 all have a negative curvature radius; the light-emitting surface of the second meniscus lens 7, the light-emitting surface of the third meniscus lens 8 and the light-emitting surface of the fourth meniscus lens 9 all have a negative curvature radius; wherein the absolute value of the curvature radius of the light-entering surface of the third meniscus lens 8 is greater than that of the third meniscus lens 8. 8; the absolute value of the radius of curvature of the light emitting surface of the third meniscus lens 8 is smaller than the absolute value of the radius of curvature of the light emitting 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 the light emitting surface of the fourth meniscus lens 9; the second meniscus lens 7 is used to enhance the beam expanding 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 track of the laser incident through the second meniscus lens 7.

[0069] Specifically, the light-entering surface of the second meniscus lens 7 is a concave surface with a negative curvature radius, and the light-exiting 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. In addition, the light-entering surface of the second meniscus lens 7 is a concave surface, and the light-exiting 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 symmetrical structure similar to a Gaussian structure, which can effectively reduce the spherical aberration of the laser passing through the lens.

[0070] 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 the light emitting surface of the third meniscus lens 8, the absolute value of the radius of curvature of the light emitting surface of the third meniscus lens 8 is smaller than the absolute value of the radius of curvature of the light emitting 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 the light emitting surface of the fourth meniscus lens 9. Exemplarily, the radius of curvature of the light incident surface of the second meniscus lens 7 is -230.941 mm, the radius of curvature of the light emitting surface of the second meniscus lens 7 is -906.219 mm, the radius of curvature of the light incident surface of the third meniscus lens 8 is -141.788 mm, and the radius of curvature of the light emitting surface of the third meniscus lens 8 is -117.956 mm, so as to ensure that the light beam further maintains its expanded light trajectory, so that the light beam expansion process remains smooth.

[0071] In some optional embodiments, the distance between two adjacent lenses among 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 satisfies:

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

[0075] When the distance between two adjacent lenses among 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 satisfies d9<d4<d5<d6<d7<d8, the beam expansion effect of the lighting system based on spherical waves is better and the expanded beam is stable.

[0076] In some optional embodiments, the third lens group includes a third positive lens 11 and a second meniscus lens group arranged in sequence along the optical axis; the light incident surface of the third positive lens 11 has a positive curvature radius, and its light exit surface is a plane, which is used to initially 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 in the direction of the holographic mask 15.

[0077] Specifically, the light-emitting surface of the second positive lens 10 is a convex surface, and the light-entering surface of the third positive lens 11 has a positive curvature radius, so it is a convex surface, that is, the second positive lens 10 and the third positive lens 11 form a mutually symmetrical structure similar to a Gaussian 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 convergence effect of the laser, that is, a stronger focusing ability, thereby increasing the numerical aperture of the illumination system and improving the lithography resolution.

[0079] In some optional 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 direction, and the light-incoming surface of the fifth meniscus lens 12, the light-incoming surface of the sixth meniscus lens 13 and the light-incoming surface of the seventh meniscus lens 14 all have a positive curvature radius; 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 all have a positive curvature radius; the curvature radius of the light-incoming surface of the third positive lens 11 is The absolute value of the radius of curvature of the light incident surface of the fifth meniscus lens 12, the absolute value of the radius of curvature of the light incident surface of the sixth meniscus lens 13, and the absolute value of the radius of curvature of the light incident surface of the seventh meniscus lens 14 decreases sequentially; the absolute value of the radius of curvature of the light exit surface of the third positive lens 11, the absolute value of the radius of curvature of the light exit surface of the fifth meniscus lens 12, the absolute value of the radius of curvature of the light exit surface of the sixth meniscus lens 13, and the absolute value of the radius of curvature of the light exit surface of the seventh meniscus lens 14 decreases sequentially.

[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 a positive curvature radius, and thus are convex surfaces. The light emitting surfaces of the fifth meniscus lens 12, the sixth meniscus lens 13 and the seventh meniscus lens 14 all have a positive curvature radius, and thus are concave surfaces. That is, the fifth meniscus lens 12, the sixth meniscus lens 13 and the seventh meniscus lens 14 all adopt one concave and one convex 1, which can reduce the spherical aberration of the system.

[0081] The curvature radius of the light incident surface of the third positive lens 11 is r111, and the curvature radius of the light emitting surface is r112; the curvature radius of the light incident surface of the fifth meniscus lens 12 is r121, and the curvature radius of the light emitting surface is r122; the curvature radius of the light incident surface of the sixth meniscus lens 13 is r131, and the curvature radius of the light emitting surface is r132; the curvature radius of the light incident surface of the seventh meniscus lens 14 is r141, and the curvature radius of the light emitting surface is r142. The respective curvature radii satisfy the following relationship: |r111|>|r121|>|r131|>|r141|, |r112|>|r122|>|r132|>|r142|. The closer to the mask, the stronger the convergence ability of the lens is, ensuring that the light beam can be converged to form an angle of 90° within an extremely short interval, with a good convergence effect, so that the illumination system obtains a larger 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. The spherical wave-based illumination system of the embodiment of the present invention can obtain a numerical aperture of 0.707 through the fifth meniscus lens 12, the sixth meniscus lens 13 and the seventh meniscus lens 14. The numerical aperture formula is:

[0083] NA=n·sinα

[0084] Among them, NA is the numerical aperture of the optical system, α is half of the imaging angle θ of the light beam, and the embodiment of the present invention uses the fifth meniscus lens 12, the sixth meniscus lens 13 and the seventh meniscus lens 14 to make the imaging angle 90°, NA=0.707, and the system has a larger numerical aperture, thereby improving the lithography resolution.

[0085] In some optional implementations, 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] Wherein, 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: 15.965mm≤d11≤16.005mm; the distance d12 between the fifth meniscus lens 12 and the sixth meniscus lens 13 satisfies: 1.605mm≤d12≤1.645mm; the distance d13 between the sixth meniscus lens 13 and the seventh meniscus lens 14 satisfies: 1.676mm≤d13≤1.716mm.

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

[0090] Further, 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 15, and the spacing 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, to facilitate 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: 13.635mm≤d10≤15.635mm; the distance d14 between the seventh meniscus lens 14 and the holographic mask 15 satisfies: 19.000mm≤d14≤21.000mm; the distance d15 between the holographic mask 15 and the focal plane 16 satisfies: 8.000mm≤d15≤10.000mm.

[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 larger because the distance between the last lens and the holographic mask 15 needs to be large enough to leave space for the mechanical structure so that the holographic mask 15 can be replaced.

[0096] In some optional implementations, an aperture is provided between the second lens group and the third lens group. The aperture can avoid stray light interference and constrain the light beam emitted by the second lens group.

[0097] In some optional embodiments, the first lens group includes a first negative lens 1 and a first meniscus lens 2 which are arranged in sequence along the optical axis, 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 which are arranged in sequence along the optical axis, 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 which are arranged in sequence along the optical axis, 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 arranged on the optical axis, the lens materials are all made of ultraviolet fused quartz and the lenses are all spherical mirrors.

[0098] The working principle of the spherical wave-based illumination system of the embodiment of the present invention is as follows: the light beam is incident from the front of the first lens group, and after being refracted by the second lens group, the field of view fills the aperture between the second positive lens 10 and the third positive lens 11, and then is refracted and focused by the third lens group, and after passing through the seventh meniscus lens 14, it is diffracted to the holographic mask 15, thereby generating an image on the focal plane 16. The holographic mask 15 is a holographic mask manufactured by holographic algorithm calculation for spherical waves. The second lens group plays the role of 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 use a combination of positive lenses, negative lenses and meniscus lenses, which can effectively reduce the system spherical aberration, 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 small overall spherical aberration. Therefore, the lens does not need to use aspherical lenses, cemented lenses or other lenses that reduce spherical aberration, but only spherical lenses. Compared with aspherical lenses and cemented lenses, spherical lenses have a simple structure and are easy to process.

[0100] The embodiment of the present invention uses two evaluation methods to evaluate the lighting system based on spherical waves.

[0101] Specifically, 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 evaluated spherical wave-based illumination system are all made of ultraviolet fused quartz, the holographic lithography illumination system works in an environment filled with nitrogen, the refractive index of ultraviolet fused quartz under nitrogen is 1.560737, the light source is a 193nm ArF laser, and the curvature radius, thickness and spacing of each lens of the spherical wave-based illumination system are shown in the following table:

[0102]

[0103]

[0104] In the above table, STO represents the aperture, and its corresponding spacing represents the spacing between the aperture and the third positive lens 11, MASK represents the holographic mask 15, and its 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 focal plane 16, and the spacings corresponding to the remaining surfaces respectively represent the middle thickness of each lens and the spacing between two adjacent lenses in 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, which are arranged in sequence, that is:

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

[0106] The curvature radius of the front surface of the first meniscus lens 2 is 65.36 mm, the curvature radius 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 curvature radius of the front surface of the second negative lens 3 is -22.261 mm, the curvature radius 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 curvature radius of the front surface of the third negative lens 4 is -463.196 mm, the curvature radius 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 curvature radius 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 curvature radius of the front surface of the second positive lens 10 is 1265.636 mm, the curvature radius 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 aperture 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 mirror 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 curvature radius of the front surface of the seventh meniscus lens 14 is 49.57 mm, the curvature radius 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. Optical Modulation Transfer Function (MTF) Evaluation

[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. Figure 4 As shown in the figure, 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 the spherical wave-based illumination system of this example has a system resolution of 3500lp / mm in the full field range when MTF≈40%. The cutoff frequency reaches 7100lp / mm.

[0122] 2. RMS wavefront aberration evaluation

[0123] like Figure 5 , Figure 6 and Figure 7As shown, the root mean square wave aberration is displayed with a wavelength λ equal to 193.368 nm as a unit. The spherical wave-based illumination system of the embodiment of the present invention has a minimum root mean square wave aberration of 0.367 nm with the central light as a reference, that is, at a field of view of 0.00°.

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

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

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

[0127] The spherical wave-based lighting system in the 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, the working wavelength is 193nm, and the numerical aperture is large. Due to the large numerical aperture, the lithography resolution is significantly improved.

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

[0131] 4. The compensation mechanism has a simple structure, and the thickness tolerance of the holographic mask 15 can be compensated and adjusted by a compensation mechanism;

[0132] 5. Through the extremely simple lens assembly, it can realize both the progressive expansion and convergence of the light beam, so that with the cooperation of the aperture, the stable output of the spherical wave can be achieved, and the precise incidence on the mask can be achieved, thereby greatly ensuring the exposure yield.

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

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

[0135] The specific implementation and beneficial effects of the exposure device can be found in the spherical wave-based illumination system of the above-mentioned embodiment, which will not be described in detail here.

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

Claims

1. A spherical wave based illumination system, applied to holographic lithography, characterized in that: It comprises a first lens group, a second lens group and a third lens group which are sequentially arranged along the optical axis direction; The first lens group is used to receive input laser light; The second lens group is used to expand the received laser beam; The third lens group is used to converge the laser beam after beam expansion and output spherical wave laser beam in the direction of the holographic mask (15).

2. The spherical wave based lighting system according to claim 1, characterized in that: The first lens group comprises a first negative lens (1) and a first meniscus lens (2) which are arranged in sequence along the optical axis direction; The light-entry surface of the first negative lens (1) has a negative curvature radius, and the light-exit surface thereof has a positive curvature radius, and is used for receiving input laser light and performing preliminary beam expansion; The light-incoming surface of the first meniscus lens (2) has a positive curvature radius, and the light-outgoing surface thereof has a positive curvature radius, and is used to further expand the laser beam that has undergone preliminary beam expansion; The absolute value of the radius of curvature of the light-emitting surface of the first meniscus lens (2) is smaller than the absolute value of the radius of curvature of the light-incoming surface of the first meniscus lens (2), and the beam expansion capability of the first meniscus lens (2) is stronger than the beam expansion capability of the first negative lens (1).

3. The spherical wave based lighting system 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 spherical wave based lighting system according to claim 1, characterized in that: It also includes a second negative lens (3) disposed between the first lens group and the second lens group along the optical axis; The light-entry surface of the second negative lens (3) has a negative curvature radius, and the light-exit surface thereof has a positive curvature radius; Wherein, the absolute value of the curvature radius of the light-emitting surface of the second negative lens (3) is greater than 600 mm.

5. The spherical wave based lighting system according to claim 4, characterized in that: The optical path compensation device further comprises a compensation mechanism, the compensation mechanism being connected to the second negative lens (3), the compensation mechanism being 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 to achieve optical path compensation by adjusting the position of the second negative lens (3) on the optical axis, wherein the moving range Δl of the second negative lens (3) satisfies the following conditions with reference to the starting position of the second negative lens (3): -1.5 mm ≤ Δl ≤ +1.5 mm.

6. The spherical wave based lighting system according to claim 1, characterized in that: The second lens group comprises 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) which are arranged in sequence along the optical axis direction; The light-entry surface of the third negative lens (4) has a negative curvature radius, and the light-exit surface thereof has a positive curvature radius, and is used for expanding the light beam incident through the first lens group; The light-entry surface of the first positive lens (5) has a positive curvature radius, and the light-exit surface thereof is a plane, and is used to converge the laser light incident through the third negative lens (4) to limit the beam expansion effect of the third negative lens (4); The light-incoming surface of the fourth negative lens (6) is a plane, and the light-outgoing surface thereof has a positive curvature radius, and is used for expanding and enhancing the laser beam incident through the first positive lens (5); The first meniscus lens group is used to enhance the beam expansion effect of the laser incident through the fourth negative lens (6) and maintain the light track of the laser in the propagation path; The light-entry surface of the second positive lens (10) has a positive curvature radius, and the light-exit surface thereof has a negative curvature radius, and is used for converting the laser light incident through the first meniscus lens group into a quasi-collimated light beam.

7. The spherical wave based lighting system according to claim 6, characterized in that: The first meniscus lens group comprises a second meniscus lens (7), a third meniscus lens (8) and a fourth meniscus lens (9) which are arranged in sequence along the optical axis direction; The light-entering surface of the second meniscus lens (7), the light-entering surface of the third meniscus lens (8) and the light-entering surface of the fourth meniscus lens (9) all have a negative radius of curvature; The light-emitting surface of the second meniscus lens (7), the light-emitting surface of the third meniscus lens (8) and the light-emitting surface of the fourth meniscus lens (9) all have a negative radius of curvature; 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 the light emitting surface of the third meniscus lens (8); the absolute value of the radius of curvature of the light emitting surface of the third meniscus lens (8) is less than the absolute value of the radius of curvature of the light emitting 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 the light emitting 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 optical trace of the laser light incident through the second meniscus lens (7).

8. The spherical wave-based lighting system according to claim 7, characterized in that: The distance between two adjacent lenses among 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) satisfies: 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).

9. The spherical wave based lighting system according to claim 8, characterized in that: The third lens group comprises a third positive lens (11) and a second meniscus lens group which are arranged in sequence along the optical axis direction; The light-entry surface of the third positive lens (11) has a positive curvature radius, and the light-exit surface is a plane, and is used to initially converge the laser light incident through the second lens group; The second meniscus lens group is used to further enhance the convergence effect of the laser light incident through the third positive lens (11), and output spherical wave laser light in the direction of the holographic mask (15).

10. The spherical wave based lighting system according to claim 9, characterized in that: The second meniscus lens group comprises a fifth meniscus lens (12), a sixth meniscus lens (13) and a seventh meniscus lens (14) which are sequentially arranged along the optical axis direction; The light-incoming surface of the fifth meniscus lens (12), the light-incoming surface of the sixth meniscus lens (13), and the light-incoming surface of the seventh meniscus lens (14) all have a positive radius of curvature; 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) all have a positive radius of curvature; The absolute value of the radius of curvature of the light incident surface of the third positive lens (11), the absolute value of the radius of curvature of the light incident surface of the fifth meniscus lens (12), the absolute value of the radius of curvature of the light incident surface of the sixth meniscus lens (13), and the absolute value of the radius of curvature of the light incident surface of the seventh meniscus lens (14) decrease in sequence; The absolute value of the radius of curvature of the light-emitting surface of the third positive lens (11), the absolute value of the radius of curvature of the light-emitting surface of the fifth meniscus lens (12), the absolute value of the radius of curvature of the light-emitting surface of the sixth meniscus lens (13), and the absolute value of the radius of curvature of the light-emitting surface of the seventh meniscus lens (14) decrease in sequence.

11. The spherical wave based lighting system according to claim 10, characterized in that: The distance between two adjacent lenses among 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 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).

12. The spherical wave based lighting system according to claim 10, characterized in that: 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 (15), and the spacing between the holographic mask (15) and the focal plane (16) satisfy: d14>d10>d15 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).

13. The spherical wave based lighting system according to claim 1, characterized in that: An aperture is provided between the second lens group and the third lens group.

14. An exposure device, applied to a chip preparation process, characterized in that: The exposure apparatus comprises a spherical wave based illumination system as claimed in any one of claims 1 to 13.

Images