A deep ultraviolet wet and dry dual-use projection objective lens and method

Abstract

The present invention provides a deep ultraviolet dry and wet dual-purpose projection objective lens and method, relating to the field of optical technology. The projection objective lens includes a plane mirror, a second lens group, an aperture, a third lens group, a fourth lens group, a fifth lens group, and a sixth lens group. By changing the thickness of the plane mirror, the projection objective lens can switch between dry imaging and wet imaging, making the projection objective lens suitable for different environments and different samples, increasing the NA value of the projection objective lens, improving the resolution of the objective lens, and making its application range more extensive. The projection objective lens can also change the numerical aperture by changing the dry imaging and wet imaging working modes. In the wet working mode, the numerical aperture can be changed by changing different immersion liquids, solving the problem that the numerical aperture and application mode of the existing projection objective lens are fixed and difficult to change.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to a deep ultraviolet wet and dry dual-purpose projection objective lens and a method. Background Art

[0002] Optical projection imaging is crucial in the photolithography process. Photolithography involves transferring the pattern on a mask through an optical projection system, miniaturizing it and transferring it to a coated silicon wafer. This requires a very high resolution from the projection optical system. It is well known that photolithography resolution can be improved by shortening the wavelength, increasing the numerical aperture, and reducing process factors. Firstly, the exposure light source for photolithography uses a shorter wavelength in the ultraviolet range; smaller wavelengths, such as 266nm, 248nm, 193nm, and even shorter wavelengths, result in higher resolution. Secondly, the numerical aperture of the optical system is increased, raising the image-side numerical aperture to 0.8 or above.

[0003] However, a large numerical aperture in a purely refractive system results in a large overall size. In limited space, increasing the numerical aperture increases design and lens manufacturing difficulties, as well as manufacturing costs. Often, once a projection objective is designed, its numerical aperture and application are fixed. Therefore, a projection objective with a variable numerical aperture and variable operating mode is needed. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects in the prior art, thereby providing a deep ultraviolet wet and dry dual-purpose projection objective lens and method.

[0005] A deep ultraviolet wet and dry dual-purpose projection objective lens, the projection objective lens comprising: a first protective mirror, a second lens group, an aperture, a third lens group, a fourth lens group, a fifth lens group and a sixth lens group, which are arranged in sequence along the optical axis from the image plane to the object plane, wherein the first protective mirror is a plane mirror, which is used to protect the objective optical system and is replaceable and has no optical focal length; when the projection objective lens is in a dry projection state, the thickness of the plane mirror is greater than that of the plane mirror when the projection objective lens is in a wet projection state; the second lens group for converging the light beam has a positive optical focal length; the third lens group for converging the light beam has a positive optical focal length; the fourth lens group for diverging the light beam and correcting the defocus of the objective optical system has a negative optical focal length; the fifth lens group for diverging the light beam and correcting the distortion of the objective optical system has a negative optical focal length; and the sixth lens group for converging the light beam has a positive optical focal length.

[0006] Furthermore, when the projection objective lens is in a dry projection state, the thickness of the plane mirror is 35 mm, and when the projection objective lens is in a wet projection state, the thickness of the plane mirror is 32 mm.

[0007] Furthermore, the object plane size of the projection objective lens is 80 mm, the image plane size of the projection objective lens is 20 mm, and the magnification of the projection objective lens is -0.25 times.

[0008] Furthermore, when the projection objective lens is in a dry projection state, the image side numerical aperture is 0.56; when the projection objective lens is in a wet projection state, the image side numerical aperture is 0.8.

[0009] Furthermore, the second lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens arranged in sequence along the optical axis from the image plane to the object plane, the first lens, the second lens, the third lens, the fourth lens and the fifth lens are all meniscus lenses, the sixth lens and the seventh lens are both biconvex lenses, and the meniscus directions of the first lens, the second lens, the third lens, the fourth lens and the fifth lens are all facing the image plane.

[0010] Furthermore, the third lens group includes an eighth lens, a ninth lens, and a tenth lens arranged in sequence along the optical axis from the image plane to the object plane. The eighth lens, the ninth lens, and the tenth lens are all meniscus lenses, and the meniscus directions of the eighth lens, the ninth lens, and the tenth lens are all facing the object plane.

[0011] Furthermore, the fourth lens group includes an eleventh lens, a twelfth lens and a thirteenth lens arranged in sequence along the optical axis from the image plane to the object plane, and the eleventh lens, the twelfth lens and the thirteenth lens are all meniscus lenses.

[0012] Furthermore, the fifth lens group includes a fourteenth lens, a fifteenth lens, and a sixteenth lens arranged in sequence along the optical axis from the image plane to the object plane, the fourteenth lens and the fifteenth lens are both meniscus lenses, and the sixteenth lens is a plano-convex lens.

[0013] Furthermore, the sixth lens group includes a seventeenth lens, an eighteenth lens, a nineteenth lens, a twentieth lens and a twenty-first lens arranged in sequence along the optical axis from the image plane to the object plane, and the seventeenth lens, the eighteenth lens, the nineteenth lens, the twentieth lens and the twenty-first lens are all meniscus lenses.

[0014] The present invention also includes a deep ultraviolet dry and wet projection method, which is implemented based on a deep ultraviolet dry and wet dual-purpose projection objective lens described in any one of the above items. In the dry projection state, the imaging object is first set on the object plane, and then the light source is emitted through the imaging object, the sixth lens group, the fifth lens group, the fourth lens group, the third lens group, the second lens group and the plane mirror in sequence, and finally the imaging object is imaged on the image plane; in the wet projection state, the thickness of the plane mirror is reduced, and the imaging object is first set on the object plane, and then the light source is emitted through the imaging object, the sixth lens group, the fifth lens group, the fourth lens group, the third lens group, the second lens group and the plane mirror in sequence, and finally the imaging object is imaged on the image plane.

[0015] The technical solution of the present invention has the following advantages:

[0016] In the technical solution provided by the present invention, the projection objective lens is switched between dry imaging and wet imaging by changing the thickness of the plane mirror, making the projection objective lens suitable for different environments and different samples, increasing the NA value of the projection objective lens, improving the resolution of the objective lens, and making its application range more extensive. The projection objective lens can also change the numerical aperture by changing the dry imaging and wet imaging working modes. When working in the wet mode, the numerical aperture can be changed by changing different immersion liquids. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention when it is in a dry projection objective state;

[0019] Figure 2 This is a modulation transfer function (MTF) curve diagram when the present invention is in a dry projection objective state;

[0020] Figure 3 The wavefront difference diagrams of different viewing fields when the present invention is in the dry projection objective state;

[0021] Figure 4 This is a diagram of field curvature and distortion when the present invention is in a dry projection objective state;

[0022] Figure 5 This is a schematic diagram of the overall structure of the present invention when it is in a wet projection objective state;

[0023] Figure 6 This is a modulation transfer function (MTF) curve diagram when the present invention is in a wet projection objective state;

[0024] Figure 7 The wavefront difference diagrams of different viewing fields when the present invention is in the wet projection objective state;

[0025] Figure 8 This is a diagram of field curvature and distortion when the present invention is in a wet projection objective state.

[0026] Description of reference numerals:

[0027] 1-image plane; 2-plane mirror; 3-first lens; 4-second lens; 5-third lens; 6-fourth lens; 7-fifth lens; 8-sixth lens; 9-seventh lens; 10-aperture stop; 11-eighth lens; 12-ninth lens; 13-tenth lens; 14-eleventh lens; 15-twelfth lens; 16-thirteenth lens; 17-fourteenth lens; 18-fifteenth lens; 19-sixteenth lens; 20-seventeenth lens; 21-eighteenth lens; 22-nineteenth lens; 23-twentieth lens; 24-twenty-first lens; 25-object plane. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0031] 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.

[0032] like Figure 1The deep ultraviolet wet and dry dual-purpose projection lens shown in the figure includes: a first protective mirror (G1 part in the figure), a second lens group (G2 part in the figure), an aperture 10, a third lens group (G3 part in the figure), a fourth lens group (G4 part in the figure), a fifth lens group (G5 part in the figure) and a sixth lens group (G6 part in the figure) arranged in sequence along the optical axis from the image plane 1 to the object plane 25. The first protective mirror is a plane mirror 2, which is a parallel flat plate protective mirror. The plane mirror 2 is used to protect the internal optical elements of the projection lens and ensure the sealing of the optical system. The replaceable plane mirror 2 used to protect the optical system of the objective lens has no optical focal length. The projection lens is in the dry projection state. The thickness of the plane mirror 2 is greater than the thickness of the plane mirror 2 when the projection objective is in the wet projection state. The second lens group for converging the light beam has positive focal power, the third lens group for converging the light beam has positive focal power, the fourth lens group for diverging the light beam and correcting the defocus of the objective optical system has negative focal power, the fifth lens group for diverging the light beam and correcting the distortion of the objective optical system has negative focal power, and the sixth lens group for converging the light beam has positive focal power. The projection objective adopts a transmissive double telecentric structure. The main light of each field of view on the object side is approximately incident on the parallel optical axis; the main light of each field of view on the image side is approximately emitted on the parallel optical axis and converges on the image plane 1. The conjugate error of the object-image plane is reduced, thereby reducing the installation error of the object plane 25; the angle between the image side and the optical axis is 2.5mrad, and the image distance is greater than 3.2mm; all lenses in the projection objective are spherical, which is convenient for processing and detection, reducing the difficulty of processing and manufacturing. The projection objective can reduce the object plane image by -0.25 times and image it into the image plane. All lenses in the projection objective are made of ARF quartz glass material. The plane mirror 2 can be replaced with parallel flat plate lenses of different thicknesses to correct the optical path difference and aberration caused by immersion when used in dry and wet projection states. The projection objective is suitable for deep ultraviolet light sources with a wavelength of 193.3 68nm, with higher resolution, the spectral width can reach 1pm, the object side working distance of the projection objective is greater than 49mm, the image side working distance is greater than 3.2mm, the thickness of the plane mirror 2 is 35mm when the projection objective is in the dry projection state, and the thickness of the plane mirror 2 is 32mm when the projection objective is in the wet projection state, the object plane size of the projection objective is 80mm, the image plane size of the projection objective is 20mm, the magnification of the projection objective is -0.25 times, the image side numerical aperture is 0.56 when the projection objective is in the dry projection state, and the image side numerical aperture is 0.8 when the projection objective is in the wet projection state, and the image side field of view is φ20mm.

[0033] The above-mentioned deep ultraviolet dual-purpose dry and wet projection objective lens realizes the switching of the projection objective lens between dry imaging and wet imaging by changing the thickness of the plane mirror 2, making the projection objective lens suitable for different environments and different samples, increasing the NA value of the projection objective lens, and improving the resolution of the objective lens, making its application range more extensive. The projection objective lens can also change the numerical aperture by changing the dry imaging and wet imaging working modes. In the wet working mode, the numerical aperture can be changed by changing different immersion liquids.

[0034] like Figure 1 As shown, in this embodiment, the second lens group includes a first lens 3, a second lens 4, a third lens 5, a fourth lens 6, a fifth lens 7, a sixth lens 8 and a seventh lens 9, which are arranged in sequence along the optical axis from the image plane 1 to the object plane 25. The first lens 3, the second lens 4, the third lens 5, the fourth lens 6 and the fifth lens 7 are all meniscus lenses, the sixth lens 8 and the seventh lens 9 are both biconvex lenses, and the meniscus directions of the first lens 3, the second lens 4, the third lens 5, the fourth lens 6 and the fifth lens 7 are all toward the image plane 1; wherein the sixth lens 8 and the seventh lens 9 are used to converge the light beam.

[0035] like Figure 1 As shown, in this embodiment, the third lens group includes an eighth lens 11, a ninth lens 12, and a tenth lens 13 arranged in sequence along the optical axis from the image plane 1 to the object plane 25. The eighth lens 11, the ninth lens 12, and the tenth lens 13 are all meniscus lenses, and the meniscus directions of the eighth lens 11, the ninth lens 12, and the tenth lens 13 are all toward the object plane 25. The third lens group is used to converge the light beam.

[0036] like Figure 1 As shown, in this embodiment, the fourth lens group includes an eleventh lens 14, a twelfth lens 15 and a thirteenth lens 16 arranged in sequence along the optical axis from the image plane 1 to the object plane 25. The eleventh lens 14, the twelfth lens 15 and the thirteenth lens 16 are all meniscus lenses; the meniscus directions of the eleventh lens 14, the twelfth lens 15 and the thirteenth lens 16 are not fixed, and it is only necessary to ensure that the fourth lens group has a negative optical power. The axial defocus is compensated by moving and adjusting the fourth lens group. The fourth lens group is used for light beam divergence, and the defocus of the objective optical system is corrected by moving the fourth lens group.

[0037] like Figure 1 As shown, in this embodiment, the fifth lens group includes a fourteenth lens 17, a fifteenth lens 18 and a sixteenth lens 19 arranged in sequence along the optical axis from the image plane 1 to the object plane 25, the fourteenth lens 17 and the fifteenth lens 18 are both meniscus lenses, and the sixteenth lens 19 is a plano-convex lens; the fifth lens group is used for light beam divergence, mainly for correcting the distortion of the objective optical system.

[0038] like Figure 1As shown, in this embodiment, the sixth lens group includes a seventeenth lens 20, an eighteenth lens 21, a nineteenth lens 22, a twentieth lens 23, and a twenty-first lens 24 arranged in sequence along the optical axis from the image plane 1 to the object plane 25. The seventeenth lens 20, the eighteenth lens 21, the nineteenth lens 22, the twentieth lens 23, and the twenty-first lens 24 are all meniscus lenses. The sixth lens group is mainly used to converge the light beam.

[0039] like Figure 1 As shown, the present invention also includes a deep ultraviolet dry and wet projection method, which is implemented based on a deep ultraviolet dry and wet dual-purpose projection objective lens described in any one of the above items. In the dry projection state, the thickness of the plane mirror 2 is 35 mm. First, the imaging object is set on the object plane 25. Then, the light source is emitted and passes through the imaging object, the sixth lens group, the fifth lens group, the fourth lens group, the third lens group, the second lens group and the plane mirror 2 in sequence. Finally, the imaging object is imaged on the image plane 1. In the wet projection state, the thickness of the plane mirror 2 is reduced to 32 mm. First, the imaging object is set on the object plane 25. Then, the light source is emitted and passes through the imaging object, the sixth lens group, the fifth lens group, the fourth lens group, the third lens group, the second lens group and the plane mirror 2 in sequence. Finally, the imaging object is imaged on the image plane 1.

[0040] Table 1 shows the specific parameters of the projection objective lens in the dry projection state. A positive radius value R indicates that the center of curvature is close to the image side, and a negative radius value R indicates that the center of curvature is close to the object side. The units of the radius, thickness, and aperture are all millimeters.

[0041] Table 1 Specific parameters of the projection objective lens in dry projection state

[0042]

[0043] like Figures 2 to 4 As shown, the projection lens provided by the present invention has good performance in the dry projection lens state, such as Figure 5 The figure shows the structure of the projection objective lens in the wet projection state, which is applicable to the 193.368nm band, with a spectral width of up to 1pm, a magnification of -0.25 times, an image-side numerical aperture of 0.8, and an image-side field of view of φ20mm.

[0044] like Figure 6 、 Figure 7 、 Figure 8As shown in FIG. 2 , the performance of the projection objective lens in the dry projection state is comparable to that in the wet projection state, with good image quality, meeting the design and use requirements. After replacing the plane mirror 2, immersion pure water is added, with a refractive index of 1.4366164. In order to meet the system image quality requirements and working distance requirements, the distance between the plane mirror 2 and the first lens 3 is increased, and the thickness of the plane mirror 2 is reduced. The specific parameters of the plane mirror 2 when the projection objective lens is in the wet projection state are shown in Table 2.

[0045] Table 2 Specific parameters of plane mirror 2 when the projection objective is in wet projection state

[0046]

[0047] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A deep ultraviolet wet and dry dual-purpose projection objective lens, characterized in that: The projection objective lens comprises: a first protective mirror, a second lens group, an aperture (10), a third lens group, a fourth lens group, a fifth lens group and a sixth lens group, which are sequentially arranged along the optical axis from the image plane (1) to the object plane (25); the first protective mirror is a plane mirror (2), which is used to protect the objective lens optical system and is replaceable and has no optical focal length; the thickness of the plane mirror (2) is greater when the projection objective lens is in a dry projection state than when the projection objective lens is in a wet projection state; the second lens group for converging the light beam has a positive focal length; the third lens group for converging the light beam has a positive focal length; the fourth lens group for diverging the light beam and correcting the defocus of the objective lens optical system has a negative focal length; the fifth lens group for diverging the light beam and correcting the distortion of the objective lens optical system has a negative focal length; and the sixth lens group for converging the light beam has a positive focal length. The third lens group comprises an eighth lens (11), a ninth lens (12) and a tenth lens (13) which are arranged in sequence along the optical axis from the image plane (1) to the object plane (25); the eighth lens (11), the ninth lens (12) and the tenth lens (13) are all meniscus lenses; and the meniscus directions of the eighth lens (11), the ninth lens (12) and the tenth lens (13) are all toward the object plane (25).

2. The deep ultraviolet wet and dry dual-purpose projection objective lens according to claim 1, characterized in that: When the projection objective lens is in a dry projection state, the thickness of the plane mirror (2) is 35 mm; when the projection objective lens is in a wet projection state, the thickness of the plane mirror (2) is 32 mm.

3. The deep ultraviolet wet and dry dual-purpose projection objective lens according to claim 1, characterized in that: The object plane size of the projection objective lens is 80 mm, the image plane size of the projection objective lens is 20 mm, and the magnification of the projection objective lens is -0.25 times.

4. The deep ultraviolet wet and dry dual-purpose projection objective lens according to claim 1, characterized in that: When the projection objective lens is in a dry projection state, the image side numerical aperture is 0.56; when the projection objective lens is in a wet projection state, the image side numerical aperture is 0.

8.

5. The deep ultraviolet wet and dry dual-purpose projection objective lens according to claim 1, characterized in that: The second lens group comprises a first lens (3), a second lens (4), a third lens (5), a fourth lens (6), a fifth lens (7), a sixth lens (8) and a seventh lens (9) which are arranged in sequence along the optical axis from the image plane (1) to the object plane (25); the first lens (3), the second lens (4), the third lens (5), the fourth lens (6) and the fifth lens (7) are all meniscus lenses; the sixth lens (8) and the seventh lens (9) are both biconvex lenses; and the meniscus directions of the first lens (3), the second lens (4), the third lens (5), the fourth lens (6) and the fifth lens (7) are all facing the image plane (1).

6. The deep ultraviolet wet and dry dual-purpose projection objective lens according to claim 1, characterized in that: The fourth lens group comprises an eleventh lens (14), a twelfth lens (15) and a thirteenth lens (16) which are arranged in sequence from the image plane (1) to the object plane (25) along the optical axis, and the eleventh lens (14), the twelfth lens (15) and the thirteenth lens (16) are all meniscus lenses.

7. The deep ultraviolet wet and dry dual-purpose projection objective lens according to claim 1, characterized in that: The fifth lens group comprises a fourteenth lens (17), a fifteenth lens (18) and a sixteenth lens (19) which are arranged in sequence from the image plane (1) to the object plane (25) along the optical axis, the fourteenth lens (17) and the fifteenth lens (18) are both meniscus lenses, and the sixteenth lens (19) is a plano-convex lens.

8. The deep ultraviolet wet and dry dual-purpose projection objective lens according to claim 1, characterized in that: The sixth lens group comprises a seventeenth lens (20), an eighteenth lens (21), a nineteenth lens (22), a twentieth lens (23) and a twenty-first lens (24) which are arranged in sequence along the optical axis from the image plane (1) to the object plane (25); the seventeenth lens (20), the eighteenth lens (21), the nineteenth lens (22), the twentieth lens (23) and the twenty-first lens (24) are all meniscus lenses.

9. A deep ultraviolet wet and dry projection method, the method being implemented based on the deep ultraviolet wet and dry dual-purpose projection objective lens according to any one of claims 1 to 8, characterized in that: In a dry projection state, the imaging object is firstly set on the object plane (25), and then the light source is emitted and sequentially passes through the imaging object, the sixth lens group, the fifth lens group, the fourth lens group, the third lens group, the second lens group and the plane mirror (2), and finally the imaging object is imaged on the image plane (1); in a wet projection state, the thickness of the plane mirror (2) is reduced, and firstly the imaging object is set on the object plane (25), and then the light source is emitted and sequentially passes through the imaging object, the sixth lens group, the fifth lens group, the fourth lens group, the third lens group, the second lens group and the plane mirror (2), and finally the imaging object is imaged on the image plane (1).

Images