Deep ultraviolet dry and wet dual-purpose projection objective lens and method

Abstract

The invention provides a deep ultraviolet dry and wet dual-purpose projection objective and method, and relates to the technical field of optics, and the projection objective comprises a plane mirror, a second lens group, a diaphragm, 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, switching between dry imaging and wet imaging of the projection objective lens is realized, so that the projection objective lens is suitable for different environments and different samples, the NA value of the projection objective lens is increased, the resolution of the objective lens is improved, and the application range of the projection objective lens is wider; in addition, the projection objective can change the numerical aperture by changing the working modes of dry imaging and wet imaging, and in the wet working mode, the numerical aperture can be changed by changing different immersion liquids, so that the problem that the numerical aperture and the application mode of the existing projection objective are fixed and difficult to change is solved.

Description

Technical Field

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

[0002] Optical projection imaging is of utmost importance in the lithography process. Lithography is to transfer the pattern on the mask plate to the coated silicon wafer after being reduced by the optical projection system, and it is required that the projection optical system has a very high resolution. As is well known, the resolution of lithography can be achieved by shortening the wavelength, increasing the numerical aperture, reducing the process factor, etc. On the one hand, the exposure light source for lithography uses the ultraviolet band with a shorter wavelength. The smaller the wavelength, the higher the resolution, such as 266 nm, 248 nm, 193 nm, etc. or even shorter wavelengths. On the other hand, increasing the numerical aperture of the optical system, increasing the image space numerical aperture to 0.8 or above.

[0003] However, in a pure refractive system with a large numerical aperture, the overall size is very large. In the case of limited space, the increase in the numerical aperture increases the design difficulty, increases the manufacturing difficulty of the lens, and also increases the manufacturing cost. Usually, after a projection objective lens is designed, its numerical aperture is already fixed, and its application method is also fixed. Therefore, a projection objective lens with a variable numerical aperture and a variable working 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, so as to provide a deep ultraviolet dry-wet dual-use projection objective lens and method.

[0005] A deep ultraviolet dry-wet dual-use projection objective lens, the projection objective lens includes: a first protective mirror, a second lens group, a diaphragm, a third lens group, a fourth lens group, a fifth lens group, and a sixth lens group arranged in sequence from the image plane to the object plane along the optical axis direction. The first protective mirror is a plane mirror, which is used to protect the objective optical system and the replaceable plane mirror has no optical power. When the projection objective lens is in the dry projection state, the thickness of the plane mirror is greater than the thickness of the plane mirror when the projection objective lens is in the wet projection state. The second lens group for converging the light beam has positive optical power, the third lens group for converging the light beam has positive optical power, the fourth lens group for diverging the light beam and correcting the defocus of the objective optical system has negative optical power, the fifth lens group for diverging the light beam and correcting the distortion of the objective optical system has negative optical power, and the sixth lens group for converging the light beam has positive optical power.

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

[0007] Further, 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] Further, when the projection objective lens is in the dry projection state, the image-side numerical aperture is 0.56, and when the projection objective lens is in the wet projection state, the image-side numerical aperture is 0.8.

[0009] Further, 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 from the image plane to the object plane along the optical axis direction. 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 all face the image plane.

[0010] Further, the third lens group includes an eighth lens, a ninth lens, and a tenth lens arranged in sequence from the image plane to the object plane along the optical axis direction. 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 all face the object plane.

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

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

[0013] Further, 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 from the image plane to the object plane along the optical axis direction. 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 further includes a deep ultraviolet dry-wet projection method, which is implemented based on a deep ultraviolet dry-wet dual-purpose projection objective lens described in any one of the above. In the dry projection state, first, an imaging object is set on the object plane, and then the light source emits light that 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, and finally the imaging object is imaged on the image plane; in the wet projection state, the thickness of the plane mirror is reduced, first, an imaging object is set on the object plane, and then the light source emits light that 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, and finally the imaging object is imaged on the image plane.

[0015] The technical solution of the present invention has the following advantages: In the technical solution provided by the present invention, by changing the thickness of the plane mirror, the switching between dry imaging and wet imaging of the projection objective is realized, so that the projection objective is applicable to different environments and different samples, the NA value of the projection objective is increased, the resolution of the objective is improved, and its application range is wider. The projection objective can also change the numerical aperture by changing the working modes of dry imaging and wet imaging. When in the wet working mode, the numerical aperture can be changed by changing different immersion liquids. Description of the Drawings

[0016] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a schematic diagram of the overall structure when the present invention is in the state of a dry projection objective; Figure 2 It is a modulation transfer function MTF curve diagram when the present invention is in the state of a dry projection objective; Figure 3 It is a wavefront aberration diagram of different fields of view when the present invention is in the state of a dry projection objective; Figure 4 It is a field curvature and distortion diagram when the present invention is in the state of a dry projection objective; Figure 5 It is a schematic diagram of the overall structure when the present invention is in the state of a wet projection objective; Figure 6 It is a modulation transfer function MTF curve diagram when the present invention is in the state of a wet projection objective; Figure 7 It is a wavefront aberration diagram of different fields of view when the present invention is in the state of a wet projection objective; Figure 8 It is a field curvature and distortion diagram when the present invention is in the state of a wet projection objective.

[0018] Explanation of the reference numerals: 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 implementation manners

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0021] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0022] 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.

[0023] Such as Figure 1A deep ultraviolet dry-wet dual-use projection objective lens as shown includes: a first protective lens (part G1 in the figure), a second lens group (part G2 in the figure), a diaphragm 10, a third lens group (part G3 in the figure), a fourth lens group (part G4 in the figure), a fifth lens group (part G5 in the figure), and a sixth lens group (part G6 in the figure) sequentially arranged along the optical axis direction from the image plane 1 to the object plane 25. The first protective lens is a plane mirror 2, and the plane mirror 2 is a parallel plate protective mirror. The plane mirror 2 is used to protect the internal optical elements of the projection objective lens, ensure the sealing of the optical system, and the plane mirror 2 that is used to protect the objective lens optical system and can be replaced has no optical power. When the projection objective 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 lens is in the wet projection state. The second lens group for converging the light beam has a positive optical power, the third lens group for converging the light beam has a positive optical power, the fourth lens group for beam divergence and correcting the defocus of the objective lens optical system has a negative optical power, the fifth lens group for beam divergence and correcting the distortion of the objective lens optical system has a negative optical power, and the sixth lens group for converging the light beam has a positive optical power. The projection objective lens adopts a transmissive double telecentric structure, and the chief rays of each field of view in the object space are approximately incident parallel to the optical axis; the chief rays of each field of view in the image space are approximately emitted parallel to the optical axis and converge at the image plane 1; the conjugate error between the object and image planes is reduced, thereby reducing the installation error of the object plane 25; the angle between the image space and the optical axis is 2.5 mrad, and the image distance is greater than 3.2 mm; all the lenses in the projection objective lens are spherical, which is convenient for processing and detection, reducing the manufacturing difficulty. The projection objective lens can reduce the image of the object plane by -0.25 times and image it into the image plane. All the lenses in the projection objective lens are made of ARF quartz glass material. The plane mirror 2 can be replaced with parallel plate lenses of different thicknesses to correct the optical path difference and aberration brought by the immersion liquid when used in the dry projection state and the wet projection state. And the projection objective lens is applicable to a deep ultraviolet band light source with a wavelength of 193.368 nm, has a higher resolution, and the spectral width can reach 1 pm. The working distance in the object space of the projection objective lens is greater than 49 mm, and the working distance in the image space is greater than 3.2 mm. When the projection objective lens is in the dry projection state, the thickness of the plane mirror 2 is 35 mm. When the projection objective lens is in the wet projection state, the thickness of the plane mirror 2 is 32 mm. The size of the object plane of the projection objective lens is 80 mm, the size of the image plane of the projection objective lens is 20 mm, the magnification of the projection objective lens is -0.25 times. When the projection objective lens is in the dry projection state, the numerical aperture in the image space is 0.56. When the projection objective lens is in the wet projection state, the numerical aperture in the image space is 0.8, and the field of view in the image space is φ20 mm.

[0024] The above-mentioned deep ultraviolet dry-wet dual-purpose projection objective lens can switch between dry imaging and wet imaging of the projection objective lens by changing the thickness of the plane mirror 2, making the projection objective lens applicable to 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 working modes of dry imaging and wet imaging. When in the wet working mode, the numerical aperture can be changed by changing different immersion liquids.

[0025] As Figure 1 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 arranged in sequence along the optical axis direction 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, and the sixth lens 8 and the seventh lens 9 are both biconvex lenses. 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 all face the image plane 1; among them, the sixth lens 8 and the seventh lens 9 are used to converge the light beam.

[0026] As Figure 1 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 direction 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 all face the object plane 25; the third lens group is used to converge the light beam.

[0027] As Figure 1 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 direction 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, as long as the fourth lens group has a negative optical power. Axial defocus is compensated by moving and adjusting the fourth lens group. The fourth lens group is used for beam divergence, and the defocus of the objective optical system is corrected by moving the fourth lens group.

[0028] As Figure 1 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 direction 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 beam divergence and is mainly used to correct the distortion of the objective optical system.

[0029] As Figure 1As shown in the figure, 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 that are sequentially arranged along the optical axis direction 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 for converging light beams.

[0030] As Figure 1 shown, the present invention further includes a deep ultraviolet dry-wet projection method, which is realized based on a deep ultraviolet dry-wet dual-purpose projection objective lens described in any one of the above. In the dry projection state, the thickness of the plane mirror 2 is 35 mm. First, an imaging object is set on the object plane 25. Secondly, the light source emits light that 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. 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, and the thickness of the plane mirror 2 is 32 mm. First, an imaging object is set on the object plane 25. Secondly, the light source emits light that 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. Finally, the imaging object is imaged on the image plane 1; Table 1 gives 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; Table 1 Specific Parameters of the Projection Objective Lens in the Dry Projection State

[0031] As Figures 2 to 4 shown, the projection objective lens provided by the present invention has good performance in the dry projection objective lens state. As Figure 5 shown, the figure is a structural diagram of the projection objective lens in the wet projection state. It is applicable to the 193.368 nm band, the spectral width can reach 1 pm, the magnification is -0.25 times, the image-side numerical aperture is 0.8, and the image-side field of view is φ20 mm; As Figure 6 , Figure 7 , Figure 8 shown, the performance of the projection objective lens in the dry projection state and the wet projection state is comparable, the image quality is good, and it meets the design and use requirements. After replacing the plane mirror 2 and adding immersion pure water with a refractive index of 1.4366164, in order to meet the system image quality requirements and the 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; Table 2 Specific Parameters of the Plane Mirror 2 when the Projection Objective Lens is in the Wet Projection State

[0032] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or alterations can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or alterations derived therefrom still fall within the protection scope of the present invention.

Claims

1. A deep ultraviolet wet and dry dual-purpose projection 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 arranged in sequence from an image plane (1) to an object plane (25) along an optical axis direction; 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; when the projection objective lens is in a dry projection state, the thickness of the plane mirror (2) is greater than the thickness of the plane mirror (2) when the projection objective lens is in a wet projection state; the second lens group for converging a light beam has a positive optical focal length; the third lens group for converging a light beam has a positive optical focal length; the fourth lens group for diverging a light beam and correcting defocus of the objective lens optical system has a negative optical focal length; the fifth lens group for diverging a light beam and correcting distortion of the objective lens optical system has a negative optical focal length; and the sixth lens group for converging a light beam has a positive optical focal length.

2. A 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, and when the projection objective lens is in a wet projection state, the thickness of the plane mirror (2) is 32 mm.

3. A 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, and 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 from the image plane (1) to the object plane (25) along the optical axis. 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 all 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 third lens group comprises an eighth lens (11), a ninth lens (12) and a tenth lens (13) which are arranged in sequence from the image plane (1) to the object plane (25) along the optical axis direction; 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 facing the object plane (25).

7. 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.

8. 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 direction; the fourteenth lens (17) and the fifteenth lens (18) are both meniscus lenses, and the sixteenth lens (19) is a plano-convex lens.

9. 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 from an image plane (1) to an object plane (25) along an optical axis, wherein 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.

10. A deep ultraviolet wet and dry projection method, which is implemented based on a deep ultraviolet wet and dry dual-purpose projection objective lens according to any one of claims 1 to 9, characterized in that: In a dry projection state, the imaging object is firstly arranged 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 arranged 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