Automatic focusing focus position offset lens barrel assembly coaxial with deep ultraviolet objective lens
By designing the automatic focus position biasing barrel assembly of the deep ultraviolet objective lens coaxial, the problem of shallow focus depth is solved, dynamic adjustment of the automatic focus focus is achieved, and the accuracy and effect of defect detection are improved.
Patent Information
- Application Number
- CN202422790054.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-15
- Publication Date
- 2025-08-22
- Estimated Expiration
- 2034-11-15
AI Technical Summary
The traditional focus system has shallow depth of focus under deep ultraviolet light, and cannot dynamically adjust the focal length, affecting the accuracy and effect of defect detection.
A coaxial autofocus focal position biasing barrel assembly of deep ultraviolet objective lens is designed. Through the combination of the barrel unit and the moving unit, the free movement of the focus within a certain range is achieved, satisfying the overlap between the autofocus focal height and the optimal detection height.
Dynamic adjustment of automatic focus focus under deep ultraviolet light is achieved, improving the accuracy and effect of defect detection.
Smart Images
Figure CN223259949U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of optical design, and specifically relates to the field of automatic focusing of a pattern wafer defect detection system, in particular to a coaxial automatic focusing focus position offset lens barrel assembly of a deep ultraviolet objective lens. Background Art
[0002] With the continuous advancement of semiconductor manufacturing technology, process dimensions are becoming increasingly refined, and correspondingly, defect sizes are also becoming smaller. Defects include particles, pattern defects, and scratches on the wafer surface. To ensure chip production quality and improve yield, efficient wafer inspection is required to identify defects even at the nanometer level. The illumination sources used in advanced process inspection equipment have reached DUV (deep ultraviolet) wavelengths, and the NA (numerical aperture) values of the objective lenses are also increasing. This results in a shallow depth of focus for DUV objective lenses.
[0003] To ensure the wafer is within the focal depth of the objective lens, the autofocus system in patterned wafer defect inspection systems must be coaxial with the DUV objective lens. Traditional focusing systems use infrared beams to minimize the impact on the illumination system. The wavelength difference between the two can cause the focusing system and the illumination system to lose focus, affecting defect detection accuracy. Furthermore, different patterns on the wafer are located at different heights, and traditional focusing systems have a fixed focal length, making it impossible to recognize all patterns on the wafer, affecting defect detection effectiveness.
[0004] Therefore, it is urgent to develop a new deep ultraviolet objective lens coaxial automatic focusing focus position offset lens barrel assembly to solve the technical problem of how to dynamically adjust the focal length during defect detection.
[0005] It should be noted that the above information disclosed in this background technology section is only used to understand the background technology of the present application concept, and therefore, the above description is not considered to constitute information of the prior art. Utility Model Content
[0006] The embodiments of the present disclosure at least provide a deep ultraviolet objective lens coaxial automatic focusing focus position offset lens barrel assembly.
[0007] In the first aspect, an embodiment of the present disclosure provides a deep ultraviolet objective lens coaxial automatic focusing focus position offset barrel assembly, which includes: a barrel unit and a moving unit; wherein the barrel unit is movably connected to the moving unit, and the barrel unit is located on the optical path; the moving unit is suitable for driving the barrel unit to move horizontally along the optical path direction to adjust the focal length of the optical path focused on the wafer through the barrel unit.
[0008] In an optional embodiment, the lens barrel unit includes: a laminated lens, a first lens and a second lens; the laminated lens, the first lens and the second lens are arranged in parallel in sequence and are respectively movably connected to the moving unit; the moving unit is suitable for driving the laminated lens, the first lens and the second lens to move synchronously.
[0009] In an optional embodiment, the curvature radius of the front side of the laminated lens is 47 mm to 49 mm; the curvature radius of the laminated surface of the laminated lens is -31 mm to -29 mm; and the curvature radius of the back side of the laminated lens is 49 mm to 51 mm.
[0010] In an optional embodiment, the curvature radius of the second front side of the first lens is -27 mm to -25 mm; the curvature radius of the second back side of the first lens is 22 mm to 24 mm.
[0011] In an optional embodiment, the radius of curvature of the front side three of the second lens is infinite; the radius of curvature of the back side three of the second lens is -34 mm to -32 mm.
[0012] In an optional embodiment, the movable unit includes: a controller, a driving member and a screw; the driving member is electrically connected to the controller, the screw is movably connected to the driving member, the barrel unit is movably connected to the screw, and the screw is arranged parallel to the optical path; the controller is suitable for sending a control signal to the driving member so that the driving member drives the screw to rotate, thereby driving the barrel unit to move horizontally along the direction of the optical path.
[0013] In an optional embodiment, a converging lens group is provided on one side of the lens barrel unit, and an objective lens is provided on the other side of the lens barrel unit; the converging lens group and the objective lens are both located on the optical path.
[0014] In an optional embodiment, a reflector and a beam splitter prism are sequentially arranged between the converging lens group and the lens barrel unit; the reflector and the beam splitter prism are both located on the optical path.
[0015] In an optional embodiment, a dichroic mirror is provided between the lens barrel unit and the objective lens; and the dichroic mirror is located on the optical path.
[0016] In an optional embodiment, a focusing light source is provided on one side of the converging mirror group, and an illumination light source is provided on one side of the dichroic mirror; the focusing light source is suitable for emitting a focusing light beam toward, and the illumination light source is suitable for emitting an illumination light beam toward the dichroic mirror.
[0017] The beneficial effect of the present invention is that the present invention movably installs the lens barrel unit on the movable unit, and the movable unit can drive the lens barrel unit to move, so as to realize the free movement of the automatic focusing focus within a certain range, meet the requirement that the automatic focusing focus height coincides with the optimal detection height, and thus achieve the best defect detection effect.
[0018] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or understood by practicing the present invention. The objectives and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.
[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0021] Figure 1 Schematic diagram of the focal length difference between the focusing light source and the illumination light source after passing through the objective lens in a traditional focusing system;
[0022] Figure 2 Schematic diagram of detecting the height difference between the focusing light source and the illumination light source on the wafer after passing through the objective lens in a traditional focusing system;
[0023] Figure 3 A structural diagram of a coaxial auto-focusing focus position offset lens barrel assembly for a deep ultraviolet objective lens provided in an embodiment of the present disclosure;
[0024] Figure 4 A block diagram of the principle of a deep ultraviolet objective lens coaxial automatic focusing focus position offset lens barrel assembly provided in an embodiment of the present disclosure;
[0025] Figure 5 An overall diagram of a deep ultraviolet objective lens coaxial automatic focusing focus position offset lens barrel assembly provided in an embodiment of the present disclosure.
[0026] In the picture:
[0027] 1. Lens barrel unit; 11. Glued lens; 111. Front side 1; 112. Glued side; 113. Back side 1; 12. First lens; 121. Front side 2; 122. Back side 2; 13. Second lens; 131. Front side 3; 132. Back side 3;
[0028] 2. Moving unit; 21. Driving member; 22. Screw;
[0029] 3. Optical path; 3a. Focused light source passes through the back focal length of the objective lens; 3b. Illumination light source passes through the back focal length of the objective lens; 3c. Height detection on the wafer after the focused light source passes through the objective lens; 3d. Height detection on the wafer after the illumination light source passes through the objective lens;
[0030] 4. Converging mirror group;
[0031] 5. Objective lens;
[0032] 6. Reflector;
[0033] 7. Beam splitter prism;
[0034] 8. Dichroic mirror;
[0035] 9a, focusing light source; 9b, illumination light source;
[0036] 10. Wafer. DETAILED DESCRIPTION
[0037] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.
[0038] In this document, when it is mentioned that a first component is located on a second component, this may mean that the first component may be directly formed on the second component, or that a third component may be interposed between the first component and the second component. In addition, in the drawings, the thickness of components may be exaggerated or reduced in order to effectively describe technical content.
[0039] The terms used herein are only used to describe specific exemplary configurations and are not intended to be limiting. As used herein, the singular articles "a", "an" and "the" may also be intended to include plural forms, unless otherwise clearly indicated herein. The terms "comprise", "include" and "have" are inclusive and therefore specify the presence of features, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components and / or combinations thereof. The method steps, processes and operations described herein should not be interpreted as necessarily requiring them to be performed in the particular order discussed or shown, unless specifically identified as an execution order. Additional or alternative steps may be adopted.
[0040] As used herein, the phrases "in one embodiment," "according to one embodiment," "in some embodiments," and the like generally refer to the fact that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present disclosure. Thus, a particular feature, structure, or characteristic may be included in more than one embodiment of the present disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms "example," "exemplary," and the like are used to "serve as an example, instance, or illustration." Any implementation, aspect, or design described herein as "example" or "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations, aspects, or designs. Instead, the use of the terms "example," "exemplary," and the like is intended to present concepts in a concrete manner.
[0041] After research, it was found that the wavelength of the illumination light source 9b is in the ultraviolet band, and the wavelength of the focusing light source 9a is in the infrared band. The chromatic aberration caused by the two wavelengths on the objective lens 5 is inevitable. Please refer to Figure 1 There is a difference between the focal length 3a of the focused light source through the objective lens and the focal length 3b of the illumination light source through the objective lens. Figure 2 There is a difference between the height 3c detected on the wafer after the focused light source passes through the objective lens and the height 3d detected on the wafer after the illumination light source passes through the objective lens, that is, different patterns on the wafer 10 will have different heights. In order to achieve the best defect detection effect, it is necessary to be able to dynamically adjust the focal length of the focusing system.
[0042] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition or explanation in subsequent drawings.
[0043] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.
[0044] like Figures 3 to 5As shown, at least one embodiment provides a coaxial automatic focusing focus position offset barrel assembly for a deep ultraviolet objective lens 5, comprising: a barrel unit 1 and a moving unit 2; wherein the barrel unit 1 is movably connected to the moving unit 2, and the barrel unit 1 is located on the optical path 3; the moving unit 2 is suitable for driving the barrel unit 1 to move horizontally along the optical path 3 to adjust the focal length of the optical path 3 focused on the wafer 10 through the barrel unit 1.
[0045] In at least one embodiment, by movably mounting the lens barrel unit 1 on the movable unit 2, the movable unit 2 can drive the lens barrel unit 1 to move, thereby enabling the automatic focus focus to move freely within a certain range, thereby satisfying the requirement that the automatic focus focus height coincides with the optimal detection height, thereby achieving the best defect detection effect.
[0046] In at least one embodiment, see Figure 3 The lens barrel unit 1 includes: a laminated lens 11, a first lens 12 and a second lens 13; the laminated lens 11, the first lens 12 and the second lens 13 are arranged in parallel in sequence and are movably connected to the moving unit 2 respectively; the moving unit 2 is suitable for driving the laminated lens 11, the first lens 12 and the second lens 13 to move synchronously.
[0047] Specifically, the glued lens 11, the first lens 12, and the second lens 13 move back and forth under the control of the moving unit 2, and the movement amount is ±5mm relative to the initial position, and the focal length can be changed by about 0.6um for every 1mm of synchronization, so the corresponding focal length adjustment range is ±3um.
[0048] Specifically, the cemented lens 11 functions to converge light beams and reduce chromatic aberration.
[0049] Specifically, the first lens 12 cooperates with the second lens 13 to adjust the divergence angle of the light beam.
[0050] In at least one embodiment, the radius of curvature of the front surface 111 of the laminated lens 11 is 47 mm to 49 mm, and the edge thickness of the front surface 111 is 9 mm to 11 mm; the radius of curvature of the bonding surface 112 of the laminated lens 11 is -31 mm to -29 mm, and the edge thickness of the bonding surface 112 is 14 mm to 16 mm; the radius of curvature of the back surface 113 of the laminated lens 11 is 49 mm to 51 mm, and the edge thickness of the back surface 113 is 109 mm to 111 mm.
[0051] Specifically, the thickness of the front surface 111 is 9mm to 11mm, and the front surface 111 is made of H-ZLAF68B optical material; the thickness of the bonding surface 112 is 14mm to 16mm, and the bonding surface 112 is made of H-ZF71 optical material; the thickness of the back surface 113 is 109mm to 111mm, and the back surface 113 is made of air optical material.
[0052] Specifically, the curvature radius of the front surface 111 is 48.52 mm, and the thickness of the front surface 111 is 10.34 mm; the curvature radius of the gluing surface 112 is -30 mm, and the thickness of the gluing surface 112 is 15.82 mm; the curvature radius of the back surface 113 is 50.82 mm, and the thickness of the back surface 113 is 110 mm.
[0053] In at least one embodiment, the radius of curvature of the front side 121 of the first lens 12 is -27mm to -25mm, and the edge thickness of the front side 121 is 14mm to 16mm; the radius of curvature of the back side 122 of the first lens 12 is 22mm to 24mm, and the edge thickness of the back side 122 is 16mm to 18mm.
[0054] Specifically, the thickness of the second front surface 121 is 14 mm to 16 mm, and the second front surface 121 is made of H-QF6A optical material; the thickness of the second back surface 122 is 16 mm to 18 mm, and the second back surface 122 is made of air optical material.
[0055] Specifically, the curvature radius of the second front surface 121 is -26.18 mm, and the thickness of the second front surface 121 is 15.5 mm; the curvature radius of the second back surface 122 is 23.3 mm, and the thickness of the second back surface 122 is 17.5 mm.
[0056] In at least one embodiment, the radius of curvature of the front three 131 on the second lens 13 is infinite, and the edge thickness of the front three 131 is 13mm to 15mm; the radius of curvature of the back three 132 on the second lens 13 is -34mm to -32mm, and the edge thickness of the back three 132 is 799mm to 801mm.
[0057] Specifically, the thickness of the front three 131 is 13mm to 15mm, and the front three 131 is made of H-LAK8A optical material; the thickness of the back three 132 is 799mm to 801mm, and the back two 122 is made of air optical material.
[0058] Specifically, the thickness of the front side three 131 is 14 mm; the curvature radius of the back side three 132 is -33 mm, and the thickness of the back side three 132 is 800 mm.
[0059] In at least one embodiment, see Figure 4 The moving unit 2 includes: a controller, a driving member 21 and a screw rod 22; the driving member 21 is electrically connected to the controller, the screw rod 22 is movably connected to the driving member 21, the barrel unit 1 is movably connected to the screw rod 22, and the screw rod is arranged parallel to the optical path 3; the controller is suitable for sending a control signal to the driving member 21, so that the driving member 21 drives the screw rod 22 to rotate, thereby driving the barrel unit 1 to move horizontally along the direction of the optical path 3.
[0060] Specifically, the controller may be a 51 single chip microcomputer, and the driving member 21 may be a stepping motor. The stepping motor drives the lead screw 22 to rotate, thereby stepping the lens barrel unit 1 .
[0061] Specifically, the electrically controlled lens barrel unit 1 can adjust the focus position of the optical path 3 and perform real-time adjustments based on the results of wafer 10 inspection.
[0062] In at least one embodiment, see Figure 5 A converging lens group 4 is provided on one side of the lens barrel unit 1 , and an objective lens 5 is provided on the other side of the lens barrel unit 1 ; the converging lens group 4 and the objective lens 5 are both located on the optical path 3 .
[0063] In at least one embodiment, see Figure 5 A reflecting mirror 6 and a beam splitting prism 7 are sequentially arranged between the converging lens group 4 and the lens barrel unit 1 ; the reflecting mirror 6 and the beam splitting prism 7 are both located on the optical path 3 .
[0064] In at least one embodiment, see Figure 5 A dichroic mirror 8 is provided between the lens barrel unit 1 and the objective lens 5 ; the dichroic mirror 8 is located on the optical path 3 .
[0065] In at least one embodiment, see Figure 5 A focusing light source 9a is provided on one side of the converging mirror group 4, and an illumination light source 9b is provided on one side of the dichroic mirror 8; the focusing light source 9a is suitable for emitting a focusing light beam toward, and the illumination light source 9b is suitable for emitting an illumination light beam toward the dichroic mirror 8.
[0066] Specifically, the lens barrel unit 1 is installed in the front optical path 3. The illumination light source 9b can determine the optimal detection height based on the type of wafer 10 and the detection effect. The lens barrel unit 1 is moved to the origin position, the corresponding automatic focus height is determined, and the lens barrel unit 1 is moved according to the optimal detection height of the illumination light source 9b until the automatic focus height coincides with the optimal detection height.
[0067] To sum up, the utility model movably installs the barrel unit on the mobile unit, and the mobile unit can drive the barrel unit to move, so as to realize the free movement of the automatic focusing focus within a certain range, meet the requirement that the automatic focusing focus height coincides with the optimal detection height, and thus achieve the best defect detection effect.
[0068] In the description of the embodiments of the present invention, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections 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.
[0069] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, terms such as "first", "second" and other numerical terms do not imply an order or sequence when used herein unless expressly indicated above. Therefore, without departing from the teachings of the example embodiments, the first element, component, region, layer or section discussed above may be referred to as a second element, component, region, layer or section.
[0070] Spatially relative terms, such as "inside," "outside," "below," "beneath," "down," "above," "on," etc., may be used herein to describe the relationship of one element or feature to another element or feature as illustrated in the figures. In addition to the orientations depicted in the figures, spatially relative terms may be intended to encompass different orientations of the device in use or operation. For example, if the device in the figures is flipped, an element described as being "below" or "below" other elements or features will be oriented to be "above" the other elements or features. Thus, the example term "below" may encompass both above and below orientations. The device may be oriented otherwise (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein are interpreted accordingly.
[0071] In the above discussion, unless otherwise indicated, the terms "about," "approximately," "substantially," etc., when used to describe a numerical value, mean a variation of + / - 10% of the value.
[0072] Based on the above-mentioned ideal embodiment of the present invention, and in accordance with the above description, relevant personnel can make various changes and modifications without departing from the technical scope of the present invention. The technical scope of the present invention is not limited to the content of the specification, but must be determined according to the scope of the claims.
Claims
1. A deep ultraviolet objective lens coaxial autofocus focus position offset lens barrel assembly, characterized in that: include: A lens barrel unit (1) and a moving unit (2); in The lens barrel unit (1) is movably connected to the moving unit (2), and the lens barrel unit (1) is located on the optical path (3); The moving unit (2) is suitable for driving the lens barrel unit (1) to move horizontally along the direction of the light path (3) to adjust the focal length of the light path (3) focused on the wafer (10) through the lens barrel unit (1).
2. The deep ultraviolet objective lens coaxial autofocus focus position offset lens barrel assembly according to claim 1, characterized in that: The lens barrel unit (1) comprises: a glued lens (11), a first lens (12) and a second lens (13); The glued lens (11), the first lens (12), and the second lens (13) are sequentially arranged in parallel and are movably connected to the moving unit (2) respectively; The moving unit (2) is suitable for driving the glued lens (11), the first lens (12), and the second lens (13) to move synchronously.
3. The deep ultraviolet objective lens coaxial autofocus focus position offset lens barrel assembly according to claim 2, characterized in that: The curvature radius of the front side (111) of the laminated lens (11) is 47 mm to 49 mm; The curvature radius of the bonding surface (112) on the bonding lens (11) is -31 mm to -29 mm; The curvature radius of the back surface (113) of the laminated lens (11) is 49 mm to 51 mm.
4. The deep ultraviolet objective lens coaxial autofocus focus position offset lens barrel assembly according to claim 2, characterized in that: The curvature radius of the second front side (121) of the first lens (12) is -27 mm to -25 mm; The curvature radius of the second back surface (122) of the first lens (12) is 22 mm to 24 mm.
5. The deep ultraviolet objective lens coaxial autofocus focus position offset lens barrel assembly according to claim 2, characterized in that: The radius of curvature of the third front face (131) of the second lens (13) is infinite; The curvature radius of the back surface three (132) of the second lens (13) is -34mm to -32mm.
6. The deep ultraviolet objective lens coaxial autofocus focus position offset lens barrel assembly according to claim 1, characterized in that: The mobile unit (2) comprises: a controller, a driving member (21) and a screw rod (22); The driving member (21) is electrically connected to the controller, the screw rod (22) is movably connected to the driving member (21), the lens barrel unit (1) is movably connected to the screw rod (22), and the screw rod is arranged parallel to the optical path (3); The controller is suitable for sending a control signal to the driving member (21), so that the driving member (21) drives the screw rod (22) to rotate, thereby driving the lens barrel unit (1) to move horizontally along the direction of the optical path (3).
7. The deep ultraviolet objective lens coaxial autofocus focus position offset lens barrel assembly according to claim 1, characterized in that: A converging lens group (4) is provided on one side of the lens barrel unit (1), and an objective lens (5) is provided on the other side of the lens barrel unit (1); The converging lens group (4) and the objective lens (5) are both located on the optical path (3).
8. The deep ultraviolet objective lens coaxial auto-focus focus position offset lens barrel assembly according to claim 7, characterized in that: A reflecting mirror (6) and a beam splitting prism (7) are sequentially arranged between the converging lens group (4) and the lens barrel unit (1); The reflector (6) and the beam splitter prism (7) are both located on the optical path (3).
9. The deep ultraviolet objective lens coaxial auto-focus focus position offset lens barrel assembly according to claim 7, characterized in that: A dichroic mirror (8) is provided between the lens barrel unit (1) and the objective lens (5); The dichroic mirrors (8) are all located on the optical path (3).
10. The deep ultraviolet objective lens coaxial auto-focus focus position offset lens barrel assembly according to claim 9, characterized in that: A focusing light source (9a) is provided on one side of the converging mirror group (4), and an illumination light source (9b) is provided on one side of the dichroic mirror (8); The focusing light source (9a) is suitable for emitting a focusing light beam toward the dichroic mirror (8), and the illumination light source (9b) is suitable for emitting an illumination light beam toward the dichroic mirror (8).