Double telecentric projection objective lens for focusing and leveling

Abstract

The invention provides a double telecentric projection objective for focusing and leveling, which is applied to the technical field of semiconductor equipment manufacturing, the double telecentric projection objective comprises an object plane, a front lens group, an aperture diaphragm, a rear lens group and an image plane which are sequentially arranged along an optical axis direction, and the front lens group and the rear lens group are symmetrically arranged along the aperture diaphragm. Therefore, the double-telecentric projection objective lens is of a refraction type and symmetrical object space and image space double-telecentric structure. The double-telecentric projection objective lens adopts a refraction type structure, compared with a reflection type structure, the double-telecentric projection objective lens is beneficial to reducing detection, installation and adjustment difficulty and reducing cost, and the double-telecentric projection objective lens adopts a symmetrical double-telecentric structure and has the advantages of being simple in structure, low in cost and good in imaging performance.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor equipment manufacturing, and in particular to a double telecentric projection objective lens for focusing and leveling. Background Art

[0002] The photolithography machine is a product of many current technologies. It projects the integrated circuit pattern on the mask onto the exposed silicon wafer coated with photoresist through a projection lens. In the photolithography machine, the silicon wafer is adjusted to the best focal plane through the focusing and leveling system to improve the accuracy of overlay. With the development of integrated circuits, the resolution of the photolithography machine continues to increase, but the focusing depth of the projection lens continues to decrease. The imaging performance of existing projection lenses is poor.

[0003] Based on this, a new technical solution is needed. Summary of the invention

[0004] In view of this, an embodiment of the present specification provides a dual telecentric projection objective lens for focusing and leveling.

[0005] The embodiments of this specification provide the following technical solutions:

[0006] An embodiment of the present specification provides a double telecentric projection objective lens for focusing and leveling, the double telecentric projection objective lens comprises an object plane, a front lens group, an aperture stop, a rear lens group and an image plane which are sequentially arranged along the optical axis direction, and the front lens group and the rear lens group are symmetrically arranged along the aperture stop, so that the double telecentric projection objective lens adopts a refractive and symmetrical object and image side double telecentric structure.

[0007] Preferably, the plurality of lenses in the front lens group and the plurality of lenses in the rear lens group are symmetrically arranged one by one along the aperture stop;

[0008] The multiple lenses in the front lens group include multiple positive lenses and multiple negative lenses. Correspondingly, the multiple lenses in the rear lens group also include multiple positive lenses and multiple negative lenses.

[0009] Preferably, the front lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens; wherein the first lens is a convex-concave negative lens, the second lens is a biconvex positive lens, the third lens is a convex-concave positive lens, the fourth lens is a biconvex positive lens, the fifth lens is a biconcave negative lens, and the sixth lens is a concave-convex negative lens;

[0010] Correspondingly, the rear lens group includes a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens and a twelfth lens; wherein the seventh lens is a convex-concave negative lens, the eighth lens is a double-concave negative lens, the ninth lens is a double-convex positive lens, the tenth lens is a concave-convex positive lens, the eleventh lens is a double-convex positive lens, and the twelfth lens is a concave-convex negative lens.

[0011] Preferably, at least two of the multiple lenses in the front lens group are made of flint glass material and two are made of crown glass material;

[0012] And / or, at least two of the multiple lenses in the rear lens group are made of flint glass material and two are made of crown glass material.

[0013] Preferably, the first lens and the sixth lens are made of flint glass material, and the second lens and the fourth lens are made of crown glass material;

[0014] And / or, the seventh lens and the twelfth lens are made of flint glass material, and the ninth lens and the eleventh lens are made of crown glass material.

[0015] Preferably, the object-side working distance D1 of the bi-telecentric projection objective lens is ≥100 mm;

[0016] And / or, a distance D5 between the fifth lens and the sixth lens satisfies 15 mm ≤ D5 ≤ 40 mm;

[0017] And / or, a distance D6 between the sixth lens and the aperture stop is ≥30 mm.

[0018] Preferably, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens satisfy the following relationship: 2≤|f1 / f2|≤5.5; 0.8≤|f3 / f6|≤1.9; 1.0≤|f4 / f5|≤2.0;

[0019] Among them, f1 represents the focal length of the first lens; f2 represents the focal length of the second lens; f3 represents the focal length of the third lens L3; f4 represents the focal length of the fourth lens; f5 represents the focal length of the fifth lens; and f6 represents the focal length of the sixth lens.

[0020] Preferably, the working wavelength band of the bi-telecentric projection objective is 600nm-1000nm;

[0021] And / or, the image-side numerical aperture of the bi-telecentric projection objective is 0.03;

[0022] And / or, the object field diameter of the bi-telecentric projection objective lens is greater than 46 mm;

[0023] And / or, the magnification of the bi-telecentric projection objective is -1.0.

[0024] Preferably, the chief ray of each field of view on the object side is incident on the first lens, and the angle between the chief ray and the optical axis is less than 0.1°; the chief ray of each field point on the image side is emitted to form an image on the image plane, and the angle between the chief ray and the optical axis is less than 0.1°.

[0025] Preferably, the bi-telecentric projection objective can be used in a focusing and leveling system in a lithography machine.

[0026] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0027] The double telecentric projection objective lens of the present application adopts a refractive structure, which is beneficial to reduce the difficulty of detection and adjustment and reduce costs compared with a reflective structure. In addition, it adopts a symmetrical double telecentric structure, which has the advantages of simple structure, low cost and good imaging performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 This is the schematic diagram of the focusing and leveling system;

[0030] Figure 2 A schematic diagram of a double telecentric projection objective structure provided in the first embodiment of the present application;

[0031] Figure 3 Field curvature, astigmatism and distortion diagram of a double telecentric projection objective provided in the first embodiment of the present application;

[0032] Figure 4 An MTF curve diagram of a double telecentric projection objective provided in the first embodiment of the present application;

[0033] Figure 5 A point diagram of a double telecentric projection objective provided in the first embodiment of the present application;

[0034] Figure 6 A schematic diagram of a double telecentric projection objective structure provided in the second embodiment of the present application;

[0035] Figure 7 Field curvature, astigmatism and distortion diagram of a double telecentric projection objective provided in the second embodiment of the present application;

[0036] Figure 8 An MTF curve diagram of a double telecentric projection objective provided in the second embodiment of the present application;

[0037] Fig. 9 A point diagram of a double telecentric projection objective provided in the second embodiment of the present application.

[0038] Figure numerals: 00, lithography objective; 10, light source module; 20, projection mark; 30, first bi-telecentric projection objective; 31, first front lens group; 32, first reflector; 33, first rear lens group; 40, silicon wafer; 50, second bi-telecentric projection objective; 51, second front lens group; 52, second reflector; 53, second rear lens group; 60, detection mark; 70, detection module. DETAILED DESCRIPTION

[0039] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0040] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0041] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0042] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0043] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the examples can be practiced without these specific details.

[0044] In view of this, the applicant conducted in-depth research and improvement exploration on the focusing and leveling system and the projection objective lens, and found that: the Chinese patent documents with publication numbers CN105242501A and CN106292197A both disclose that the focusing and leveling system uses a refractive projection objective lens, but only provide the schematic diagram of the projection objective lens, without providing specific design parameters and imaging quality. The Chinese patent document with publication number CN114690571A discloses that the focusing and leveling system uses a reflective projection objective lens, and does not provide specific design parameters. Compared with the refractive system, the reflective objective lens has strict processing and inspection requirements, is difficult to assemble and adjust, and has a higher cost. Almost no patent documents provide specific solutions for projection objective lenses in focusing and leveling systems.

[0045] Based on this, the technical solutions provided by the embodiments of the present application are described below in conjunction with the accompanying drawings.

[0046] The first embodiment of this specification proposes a double telecentric projection objective lens for focusing and leveling: Figure 2 As shown, it can be used in the focusing and leveling system of the lithography machine. The double telecentric projection objective lens includes an object plane, a front lens group, an aperture stop, a rear lens group and an image plane arranged in sequence along the optical axis direction, and the front lens group and the rear lens group are symmetrically arranged along the aperture stop, so that the double telecentric projection objective lens is a refractive and symmetrical object and image side double telecentric structure. Among them, the object plane and the image plane can be symmetrically arranged along the aperture stop. The double telecentric projection objective lens is an object and image side double telecentric structure and both are spherical lenses. Figure 2 Here, G1 represents the front lens group, and G2 represents the rear lens group.

[0047] In one embodiment, the multiple lenses in the front lens group and the multiple lenses in the rear lens group are symmetrically arranged along the aperture stop; the multiple lenses in the front lens group include multiple positive lenses and multiple negative lenses, and correspondingly, the multiple lenses in the rear lens group also include multiple positive lenses and multiple negative lenses.

[0048] For example, the front lens group includes six lenses, and the six lenses include three positive lenses and three negative lenses, the rear lens group includes six lenses, and the six lenses include three positive lenses and three negative lenses, and the front lens group and the rear lens group are symmetrical about the aperture stop. The materials, positions and shapes of the multiple lenses in the front lens group and the multiple lenses in the rear lens group are symmetrically arranged one by one along the aperture stop.

[0049] In one embodiment, the front lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens, and are arranged in sequence; wherein the first lens is a convex-concave negative lens, the second lens is a biconvex positive lens, the third lens is a convex-concave positive lens, the fourth lens is a biconvex positive lens, the fifth lens is a biconcave negative lens, and the sixth lens is a concave-convex negative lens.

[0050] Correspondingly, the rear lens group includes a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens and a twelfth lens, and are arranged in sequence; wherein the seventh lens is a convex-concave negative lens, the eighth lens is a double-concave negative lens, the ninth lens is a double-convex positive lens, the tenth lens is a concave-convex positive lens, the eleventh lens is a double-convex positive lens, and the twelfth lens is a concave-convex negative lens. Figure 2 In the figure, L1 represents the first lens, L2 represents the second lens, L3 represents the third lens, L4 represents the fourth lens, L5 represents the fifth lens, L6 represents the sixth lens, L7 represents the seventh lens, L8 represents the eighth lens, L9 represents the ninth lens, L10 represents the tenth lens, L11 represents the eleventh lens, and L12 represents the twelfth lens.

[0051] In one embodiment, at least two of the multiple lenses in the front lens group are made of flint glass material and two are made of crown glass material; and / or, at least two of the multiple lenses in the rear lens group are made of flint glass material and two are made of crown glass material.

[0052] In one embodiment, the first lens and the sixth lens are made of flint glass, and the second lens and the fourth lens are made of crown glass; and / or the seventh lens and the twelfth lens are made of flint glass, and the ninth lens and the eleventh lens are made of crown glass.

[0053] For example, the front lens group contains at least 2 flint glass materials and 2 crown glass materials, wherein the flint glass material is the convex-concave negative lens corresponding to the first lens and the concave-convex negative lens corresponding to the sixth lens, and the crown glass material is the biconvex positive lens corresponding to the second lens and the biconvex positive lens corresponding to the fourth lens. The rear lens group contains at least 2 flint glass materials and 2 crown glass materials, wherein the flint glass material is the convex-concave negative lens corresponding to the seventh lens and the concave-convex negative lens corresponding to the twelfth lens, and the crown glass material is the biconvex positive lens corresponding to the ninth lens and the biconvex positive lens corresponding to the eleventh lens.

[0054] Optical materials can generally be divided into two categories according to the size of refractive index and Abbe number: flint glass material and crown glass material. Flint glass material: high refractive index material with low Abbe number, that is, the refractive index nd is greater than 1.60 and the Abbe number vd is less than 50; Crown glass material: low refractive index material with high Abbe number, that is, the refractive index nd is less than 1.60 and the Abbe number vd is greater than 55.

[0055] In one embodiment, the object side working distance D1 of the double telecentric projection objective lens is ≥100 mm; and / or, the distance D5 between the fifth lens and the sixth lens satisfies 15 mm≤D5≤40 mm; and / or, the distance D6 between the sixth lens and the aperture stop is ≥30 mm.

[0056] In one embodiment, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens satisfy the following relationships: 2≤|f1 / f2|≤5.5; 0.8≤|f3 / f6|≤1.9; 1.0≤|f4 / f5|≤2.0.

[0057] Among them, f1 represents the focal length of the first lens; f2 represents the focal length of the second lens; f3 represents the focal length of the third lens L3; f4 represents the focal length of the fourth lens; f5 represents the focal length of the fifth lens; and f6 represents the focal length of the sixth lens.

[0058] like Figure 2 As shown, the double telecentric projection objective lens of this embodiment includes 12 optical lenses, one object plane, one aperture stop, and one image plane; the designed double telecentric projection objective lens is sequentially provided with five parts, namely, the object plane, the front lens group, the aperture stop, the rear lens group, and the image plane, along the optical axis direction. This embodiment adopts a symmetrical structure, which can effectively correct aberrations and improve imaging quality.

[0059] In one embodiment, the operating band of the bi-telecentric projection objective is 600nm-1000nm; and / or, the image-side numerical aperture of the bi-telecentric projection objective is 0.03; and / or, the object-side field of view diameter of the bi-telecentric projection objective is greater than 46mm; and / or, the magnification of the bi-telecentric projection objective is -1.0.

[0060] In one embodiment, the chief ray of each field of view on the object side is incident on the first lens, and the angle between the chief ray and the optical axis is less than 0.1°; the chief ray of each field of view point on the image side is emitted and imaged on the image plane, and the angle between the chief ray and the optical axis is less than 0.1°. Specifically, the double telecentric projection objective has a double telecentric structure of the object and image sides, the chief ray of each field of view on the object side is incident on the first lens approximately parallel to the optical axis, and the angle between the chief ray and the optical axis is less than 0.1°, the chief ray of each field of view point on the image side is emitted approximately parallel to the optical axis and imaged on the image plane, and the angle between the chief ray and the optical axis is less than 0.1°.

[0061] The field curvature, astigmatism and distortion of the double telecentric projection objective are as follows: Figure 3 As shown, the field curvature is within 0.025mm, the distortion is less than 0.01%, and the astigmatism is also well corrected. Figure 3 In the figure, ASTIGMATIC FIELD CURVES means field curvature; DISTORTION means distortion; FOCUS (MILLIMETERS) means focus (millimeter).

[0062] The MTF curve of the double telecentric projection objective is as follows: Figure 4As shown, the horizontal axis is the spatial frequency, the vertical axis is the MTF value, and the MTF curve is close to the diffraction limit, which has good imaging quality. Figure 4 In the specification, Modulation refers to MTF (Modulation Transfer Function), which is used to evaluate the imaging quality of the optical system; Spatial Frequency (cycles / mm) refers to spatial frequency (line pairs / mm).

[0063] The point diagram of the double telecentric projection objective is as follows: Figure 5 As shown, the diffuse spots are all within the Airy disk, and the imaging quality is good. Figure 5 In the figure, FIELD POSITION indicates the field position; DEFOCUSING indicates defocusing.

[0064] The specific optical parameters of the double telecentric projection objective in this embodiment are shown in Table 1.

[0065] Table 1 Specific optical parameters of the double telecentric projection objective lens of the first embodiment

[0066]

[0067]

[0068] Among them, Sphere represents a spherical surface.

[0069] In one embodiment, the dual telecentric projection objective can be used in a focusing and leveling system in a lithography machine, such as Figure 1 As shown, a focusing and leveling system is provided, which includes a lithography objective lens 00, a light source module 10, a projection mark 20, a first double telecentric projection objective lens 30, a silicon wafer 40, a second double telecentric projection objective lens 50, a detection mark 60 and a detection module 70; light emitted by the light source module 10 irradiates the projection mark 20, and the projection mark 20 is imaged onto the silicon wafer 40 through the first double telecentric projection objective lens 30, and after being reflected by the surface of the silicon wafer 40, the light with the height information of the silicon wafer 40 is imaged onto the detection mark 60 through the second double telecentric projection objective lens 50, and is received by the detection module 70, and the defocus amount of the silicon wafer 40 is obtained by calculation.

[0070] The first bi-telecentric projection objective lens 30 may include a first front lens group 31, a first reflector 32, and a first rear lens group 33; the second bi-telecentric projection objective lens 50 may include a second front lens group 51, a second reflector 52, and a second rear lens group 53. In addition, the first bi-telecentric projection objective lens 30 and / or the second bi-telecentric projection objective lens 50 may use any of the above-mentioned bi-telecentric projection objective lenses for focusing and leveling.

[0071] The second embodiment of this specification discloses a dual telecentric projection objective lens, which can be used in a focusing and leveling system in a photolithography machine, such as Figure 6 As shown, the object plane, the front lens group G1, the aperture stop, the rear lens group G2 and the image plane are arranged in sequence along the optical axis direction; the front lens group G1 includes six lenses from L1 to L6, and the six lenses include three positive lenses and three negative lenses, the rear lens group includes six lenses from L7 to L12, and the six lenses include three positive lenses and three negative lenses, and the front lens group G1 and the rear lens group G2 are symmetrical about the aperture stop.

[0072] The projection objective lens is a double telecentric structure for the object and image sides and both are spherical lenses. The front lens group G1 includes:

[0073] Convex-concave negative lens L1, biconvex positive lens L2, convex-concave positive lens L3, biconvex positive lens L4, biconcave negative lens L5, and concave-convex negative lens L6. The rear lens group G2 includes: convex-concave negative lens L7, biconcave negative lens L8, biconvex positive lens L9, concave-convex positive lens L10, biconvex positive lens L11, and concave-convex negative lens L12.

[0074] The front lens group G1 contains at least 2 flint glass materials and 2 crown glass materials, wherein the flint glass materials are convex-concave negative lens L1 and concave-convex negative lens L6, and the crown glass materials are biconvex positive lens L2 and biconvex positive lens L4; the rear lens group G2 contains at least 2 flint glass materials and 2 crown glass materials, wherein the flint glass materials are convex-concave negative lens L7 and concave-convex negative lens L12, and the crown glass materials are biconvex positive lens L9 and biconvex positive lens L11.

[0075] The object side working distance L1 of the double telecentric projection objective lens is ≥100 mm; the distance between the fifth lens and the first lens satisfies 15 mm ≤ L5 ≤ 40 mm; the distance between the sixth lens and the aperture stop is L6 ≥30 mm.

[0076] The first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the fifth lens L5 satisfy the following relationships: 2≤|f1 / f2|≤5.5; 0.8≤|f3 / f6|≤1.9; 1.0≤|f4 / f5|≤2.0.

[0077] Among them, f1: the focal length of the first lens L1; f2: the focal length of the second lens L2; ​​f3: the focal length of the third lens L3; f4: the focal length of the fourth lens L4; f5: the focal length of the fifth lens L5; f6: the focal length of the sixth lens L6.

[0078] A double telecentric projection objective lens of the present embodiment comprises 12 optical lenses, an object plane, an aperture stop and an image plane; the designed double telecentric projection objective lens is provided with five parts, namely, an object plane, a front lens group G1, an aperture stop, a rear lens group G2 and an image plane, in sequence from the incident direction of the light beam.

[0079] The working band of the double telecentric projection objective lens of the present embodiment is 600nm-1000nm; the image-side numerical aperture of the double telecentric projection objective lens of the present embodiment is 0.03; the object-side field of view diameter of the double telecentric projection objective lens of the present embodiment is greater than 46mm; the magnification of the double telecentric projection objective lens of the present embodiment is -1.0; the present embodiment adopts a symmetrical structure, which can effectively correct aberrations and improve imaging quality.

[0080] The double telecentric projection objective lens of this embodiment has a double telecentric structure for the object and image sides. The chief light of each field of view on the object side is approximately parallel to the optical axis and is incident on the first lens, and the angle between the chief light and the optical axis is less than 0.1°. The chief light of each field of view point on the image side is approximately parallel to the optical axis and is imaged on the image plane, and the angle between the chief light and the optical axis is less than 0.1°.

[0081] The field curvature, astigmatism and distortion of the double telecentric projection lens of this embodiment are as follows: Figure 7 As shown, the field curvature is within 0.025mm, the distortion is less than 0.01%, and the astigmatism is also well corrected.

[0082] The MTF curve of the double telecentric projection objective lens of this embodiment is as follows: Figure 8 As shown, the horizontal axis is the spatial frequency, the vertical axis is the MTF value, and the MTF curve is close to the diffraction limit, which has good imaging quality.

[0083] The point diagram of the double telecentric projection objective lens of this embodiment is as follows: Fig. 9 As shown, the diffuse spots are all within the Airy disk, and the imaging quality is good.

[0084] The specific optical parameters of the dual telecentric projection objective lens of this embodiment are shown in Table 2.

[0085] Table 2 Specific optical parameters of the bi-telecentric projection objective lens of the second embodiment

[0086]

[0087]

[0088] In the table, L1, L2, L3, L4, L5, L6, L7, L8, L9, L10, L11 and L12 respectively represent: convex-concave negative lens L1, biconvex positive lens L2, convex-concave positive lens L3, biconvex positive lens L4, biconcave negative lens L5, convex-concave negative lens L6, convex-concave negative lens L7, biconcave negative lens L8, biconvex positive lens L9, concave-convex positive lens L10, biconvex positive lens L11 and convex-concave negative lens L12.

[0089] The present application provides a dual-telecentric projection objective lens that can be used in a focusing and leveling system of a lithography machine. The objective lens operates in the 600nm-1000nm band and adopts a symmetrical dual-telecentric structure. It has the advantages of simple structure, low cost and good imaging performance.

[0090] In this specification, the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiments described later, the description is relatively simple, and the relevant parts can be referred to the partial description of the previous embodiments.

[0091] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A dual telecentric projection objective lens for focusing and leveling, characterized in that: The double telecentric projection objective lens comprises an object plane, a front lens group, an aperture stop, a rear lens group and an image plane which are sequentially arranged along the optical axis direction, and the front lens group and the rear lens group are symmetrically arranged along the aperture stop, so that the double telecentric projection objective lens adopts a refractive and symmetrical object and image side double telecentric structure.

2. The double telecentric projection objective lens for focusing and leveling according to claim 1, characterized in that: The plurality of lenses in the front lens group and the plurality of lenses in the rear lens group are symmetrically arranged one by one along the aperture stop; The multiple lenses in the front lens group include multiple positive lenses and multiple negative lenses. Correspondingly, the multiple lenses in the rear lens group also include multiple positive lenses and multiple negative lenses.

3. The double telecentric projection objective lens for focusing and leveling according to claim 2, characterized in that: The front lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens; wherein the first lens is a convex-concave negative lens, the second lens is a biconvex positive lens, the third lens is a convex-concave positive lens, the fourth lens is a biconvex positive lens, the fifth lens is a biconcave negative lens, and the sixth lens is a concave-convex negative lens; Correspondingly, the rear lens group includes a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens and a twelfth lens; wherein the seventh lens is a convex-concave negative lens, the eighth lens is a double-concave negative lens, the ninth lens is a double-convex positive lens, the tenth lens is a concave-convex positive lens, the eleventh lens is a double-convex positive lens, and the twelfth lens is a concave-convex negative lens.

4. The double telecentric projection objective lens for focusing and leveling according to claim 2, characterized in that: The plurality of lenses in the front lens group include at least two lenses made of flint glass and two lenses made of crown glass; And / or, at least two of the multiple lenses in the rear lens group are made of flint glass material and two are made of crown glass material.

5. The double telecentric projection objective lens for focusing and leveling according to claim 3, characterized in that: The first lens and the sixth lens are made of flint glass, and the second lens and the fourth lens are made of crown glass; And / or, the seventh lens and the twelfth lens are made of flint glass material, and the ninth lens and the eleventh lens are made of crown glass material.

6. The double telecentric projection objective lens for focusing and leveling according to claim 3, characterized in that: The object side working distance D1 of the bi-telecentric projection objective lens is ≥ 100 mm; And / or, a distance D5 between the fifth lens and the sixth lens satisfies 15 mm ≤ D5 ≤ 40 mm; And / or, a distance D6 between the sixth lens and the aperture stop is ≥30 mm.

7. The double telecentric projection objective lens for focusing and leveling according to claim 3, characterized in that: The first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens satisfy the following relationship: 2≤|f1 / f2|≤5.5; 0.8≤|f3 / f6|≤1.9; 1.0≤|f4 / f5|≤2.0; Among them, f1 represents the focal length of the first lens; f2 represents the focal length of the second lens; f3 represents the focal length of the third lens L3; f4 represents the focal length of the fourth lens; f5 represents the focal length of the fifth lens; and f6 represents the focal length of the sixth lens.

8. The double telecentric projection objective lens for focusing and leveling according to claim 1, characterized in that: The working band of the bi-telecentric projection objective is 600nm-1000nm; And / or, the image-side numerical aperture of the bi-telecentric projection objective is 0.03; And / or, the object field diameter of the bi-telecentric projection objective lens is greater than 46 mm; And / or, the magnification of the bi-telecentric projection objective is -1.

0.

9. The double telecentric projection objective lens for focusing and leveling according to claim 3, characterized in that: The chief ray of each field of view on the object side is incident on the first lens, and the angle between the chief ray and the optical axis is less than 0.1°; the chief ray of each field point on the image side is emitted to form an image on the image plane, and the angle between the chief ray and the optical axis is less than 0.1°.

10. The double telecentric projection objective lens for focusing and leveling according to any one of claims 1 to 9, characterized in that: The double telecentric projection objective can be used in the focusing and leveling system of a lithography machine.

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