Lifter assembly with bellows for optical inspection system

Abstract

A lifter assembly for an optical system includes a chuck including a chuck base and a removable top plate. The removable top plate is one of a plurality of interchangeable removable top plates configured to support a substrate. The lifter assembly also includes a movable plate supporting the chuck on an upper surface thereof, the movable plate being vertically adjustable between a lower, retracted position and an upper, extended position. The lifter assembly further includes a bellows structure operatively coupled to the movable plate. The lifter assembly further includes a pneumatic system fluidly coupled to the bellows structure and configured to selectively extend and retract the bellows structure. The pneumatic system extends the bellows structure to vertically adjust the movable plate to the upper, extended position and retracts the bellows structure to vertically adjust the movable plate to the lower, retracted position.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 63 / 430,412, filed December 6, 2022, the disclosure of which is incorporated herein by reference in its entirety.

[0002] FIELD OF THE INVENTION The embodiments described herein relate to optical inspection systems, and more particularly to pneumatic lifter assemblies for such systems. [Background technology]

[0003] Inspection procedures are used at various steps in the semiconductor manufacturing process to detect defects on wafers to promote higher yields in the manufacturing process and thereby achieve higher profits. Inspection has always played an important role in the production of semiconductor devices. However, as semiconductor devices become smaller, inspection becomes even more important to successfully produce acceptable semiconductor devices, as smaller defects can result in device failure.

[0004] Assembly, metrology, and defect inspection processes may require vertical, or up-and-down, movement of a chuck with a substrate resting on it. A lifter assembly supports the chuck and actuates its up-and-down movement. For example, a pneumatic rod is located within the chamber of the lifter assembly and connected to a support member and a movable plate to introduce and remove fluid to move the chuck up and down. Some tools that work in conjunction with the lifter assembly may have limited space to accommodate all of the lifter assembly components in operation. The pneumatic rods described above occupy more space when the lifter assembly is extended from its retracted (i.e., lower) position to its upper position. Furthermore, pneumatic rods may not be able to maintain perpendicularity to the adjacent support member when uneven loads are elevated or applied, resulting in wear on the interior of the bore through which the rod slides. Furthermore, pneumatic rods can only extend to a fixed, non-adjustable stroke length. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2002 / 0104453 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-104667 Summary of the Invention [Problem to be solved by the invention]

[0006] The above issues pose challenges to the substrate inspection process. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, a lifter assembly for an optical system includes a chuck having a chuck base and a removable top plate, the removable top plate being one of a plurality of interchangeable removable top plates configured to support a substrate. The lifter assembly also includes a movable plate supporting the chuck on an upper surface thereof, the movable plate being vertically adjustable between a lower, retracted position and an upper, extended position. The lifter assembly further includes a bellows structure operatively or operatively coupled to the movable plate. The lifter assembly further includes a pneumatic system fluidly coupled to the bellows structure for selectively extending and retracting the bellows structure. The pneumatic system extends the bellows structure to vertically adjust the movable plate to the upper, extended position and retracts the bellows structure to vertically adjust the movable plate to the lower, retracted position.

[0008] According to another aspect of the present disclosure, an optical system includes a substrate chucking subsystem including a chuck having a chuck base and a removable upper plate that supports a substrate. The optical system further includes a movable plate supporting the chuck on an upper surface, the movable plate being vertically adjustable between a lower retracted position and an upper extended position. The optical system further includes a bellows structure operatively coupled to the movable plate, the bellows structure extending to vertically adjust the movable plate to the upper extended position and the bellows structure contracting to vertically adjust the movable plate to the lower retracted position. The optical system further includes an illumination source configured to illuminate one or more portions of the substrate. The optical system further includes a detector configured to collect illumination from the illuminated one or more portions of the substrate.

[0009] According to yet another aspect of the present disclosure, a lifter assembly for vertically moving a substrate includes a vacuum chuck configured to support the substrate and to hold the substrate by vacuum pressure. The lifter assembly further includes a movable plate supporting the vacuum chuck on an upper surface thereof, the movable plate being vertically adjustable between a lower retracted position and an upper extended position. The lifter assembly further includes a welded bellows structure operably coupled to the movable plate, the welded bellows structure adjusting the movable plate to the upper extended position by expanding the welded bellows structure and adjusting the movable plate to the lower retracted position by contracting the welded bellows structure.

[0010] These aspects and other advantages and features will become apparent from the following description taken in conjunction with the drawings. [Brief explanation of the drawings]

[0011] The subject matter that is an embodiment of the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The features and advantages of the disclosed embodiments will be apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0012] [Figure 1]FIG. 1 is a partial cross-sectional elevation view of an optical inspection system lifter assembly supporting a chuck. [Figure 2] FIG. 2 is a perspective view of a lifter assembly. [Figure 3A] 1 shows the lifter assembly in a retracted position with fluid lines connected. [Figure 3B] 1 shows the lifter assembly in an extended position with fluid lines connected. [Figure 4A] 1 shows the lifter assembly in a retracted position. [Figure 4B] 1 shows the lifter assembly in an extended position. [Figure 5] FIG. 10 is a cross-sectional elevation view of a lifter assembly according to another aspect of the present disclosure. [Figure 6A] 1A and 1B illustrate schematic diagrams of systems incorporating embodiments of the lifter assemblies described herein, according to one aspect of the present disclosure. [Figure 6B] 10A-10C schematically illustrate systems incorporating embodiments of the lifter assemblies described herein, according to another aspect of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] The invention shown in the drawings will be described in connection with specific embodiments. With reference to the drawings, it will be understood that the disclosed embodiments are merely exemplary of the invention, and that the invention can be embodied in various and alternative forms. The drawings may not necessarily be to scale, and certain features may be exaggerated, reduced, or simplified to show the details of particular components. Therefore, the specific structural and functional details disclosed herein and illustrated in the drawings should not be construed as limiting, but rather as providing a representative basis for various uses of the invention by those skilled in the art.

[0014] Referring to FIG. 1 , a portion of a substrate chucking system for an optical system is generally indicated at 11. An embodiment of a lifter assembly 10 is disclosed that supports and vertically adjusts a chuck 14. The lifter assembly 10 includes a movable plate 12 that supports the chuck 14. The chuck 14 is configured to support a substrate, such as a semiconductor wafer (not shown). Various contemplated chucks can be used with the lifter assembly 10 disclosed herein. For example, but not limited to, the lifter assembly 10 can be used with the substrate chucking system disclosed in U.S. Patent Application No. 17 / 562,544, which is incorporated herein by reference in its entirety. In the illustrated embodiment, the chuck 14 is a vacuum chuck that holds a substrate in place on an upper surface 13 of the chuck 14 by vacuum pressure delivered through the chuck 14 via one or more vacuum inlets 15 and a vacuum reservoir 17. Furthermore, in the illustrated embodiment, the chuck 14 includes a chuck base 16 and a removable plate 18. The removable plate 18 is secured to the chuck base 16 by one or more fasteners or guides 20. However, it will be understood that it is within the scope of the disclosed embodiments to have a chuck 14 of unitary construction.

[0015] The chuck base 16 is configured to allow different types of removable plates 18 to be secured thereto. The removable plates 18 are suitable for rapid replacement on the chuck base 16. Such a configuration is more time- and cost-effective in the substrate chuck replacement process because a common chuck can accommodate multiple top plates used for a variety of substrates.

[0016] Regardless of the particular type of chuck, overall tool / stage, and optical system, the embodiments of the lifter assembly 10 disclosed herein include a bellows structure 22 that drives the generally vertical movement of the movable plate 12, and thus the chuck 14 and substrate supported on the movable plate 12. In some embodiments, the bellows structure 22 is a welded bellows type. The bellows structure 22 is formed in an accordion configuration, with multiple annular bellows plates having radially curved surfaces connected alternately to the outer and inner diameters. The bellows plates are connected to each other, for example, by TIG welding in air or an Ar gas environment. The bellows structure 22 defines a hollow interior chamber.

[0017] Vertical adjustment of the movable plate 12 changes the distance between the chuck 14 that holds the substrate and the measurement device of the optical system. Here, the term "measurement device" is used broadly to mean a metrology device, an inspection device, or a metrology inspection device. Vertical adjustment of the movable plate 12, chuck 14, and the substrate facilitates various operations by the optical system.

[0018] Referring to Figure 2, the lifter assembly 10 is shown in further detail. As shown, the fixture and guide 20 are radially outward from the vacuum inlet 15 in the illustrated embodiment. This is the opposite of the configuration shown in Figure 1. As such, either configuration is contemplated.

[0019] The movable plate 12 in the illustrated embodiment has a central portion 24 and a plurality of arms 26 extending from the central portion 24. Specifically, the illustrated embodiment has three arms. However, in other embodiments, a different number of arms may be used. The lifter assembly 10 further includes a base flange 28 and a top cap 30. A plurality of guide shafts 32 extend through respective holes in the movable plate 12 and are operatively connected to the base flange 28 and the top cap 30. Each guide shaft 32 may have a threaded end and couple to threaded regions on the base flange 28 and the top cap 30. Alternatively, the guide shafts 32 may be coupled to the base flange 28 and the top cap 30 by nuts or the like. The bellows structure 22 drives the vertical adjustment of the movable plate 12, the chuck 14, and the substrate, while the guide shafts 32 guide and maintain this vertical adjustment. The number of guide shafts 32 may vary depending on the particular application.

[0020] 3A and 3B, with continued reference to FIG. 2, the lifter assembly 10 is fluidly coupled to a pneumatic system 40. A first fluid connection is made between at least one of the plurality of arms 26 via a piping structure 42 of the movable plate 12. This first fluid connection provides the vacuum pressure necessary to hold the substrate to the chuck 14, as described below. A second fluid connection is made between the interior chamber of the bellows structure 22 and a selectively switchable supply from a compressed air source 44 or a vacuum pressure source 46 via a second piping structure 48. With respect to the second fluid connection, a ported solenoid 50 includes an inlet 52 for receiving compressed air from the compressed air source 44, an outlet 54 for delivering compressed air to the interior chamber of the bellows structure 22, and an exhaust 56 for drawing compressed air from the interior chamber of the bellows structure 22 via the vacuum pressure source 46.

[0021] Although the ported solenoid 50 in the illustrated embodiment is a three-way solenoid, other types of piping structures may be utilized for the second fluid connection to selectively route compressed air into or out of the interior chamber of the bellows structure 22. In the illustrated embodiment of the ported solenoid 50, vacuum air pressure is supplied to the bellows structure 22 to contract the bellows structure 22, thereby lowering the movable plate 12 when the ported solenoid 50 is de-energized. Conversely, when the ported solenoid 50 is energized, compressed air enters the bellows structure 22 through a preset pressure regulator 58 to a pressure value sufficient to expand the bellows structure 22, thereby raising the moving mass including the movable plate 12 and the chuck 14 and the substrate supported thereon.

[0022] 4A and 4B, the lifter assembly 10 according to the first embodiment is shown in more detail. The bellows structure 22 is vertically adjustable between a lower, retracted position (FIG. 4A) and an upper, extended position (FIG. 4B), thereby vertically adjusting the movable plate 12, the chuck 14, and the substrate. As described above, a plurality of guide shafts 32 extend through respective holes in the movable plate 12 and are operatively coupled to the base flange 28 and the top cap 30 to guide the movable plate 12 during its vertical movement. A plurality of bushing structures 60 provide stable movement along the guide shafts 32 during the movable plate 12's vertical movement. In particular, the movable plate 12 has a number of bushing structures 60 on its upper surface 62 corresponding to the number of guide shafts 32. Thus, each guide shaft 32 passes through a corresponding bushing structure 60. Each bushing structure 60 has a bushing housing 64 that houses a bushing 68. The bushing structure 60 concentrically surrounds the guide shaft 32 and moves with the movable plate 12 .

[0023] The lower retracted position (FIG. 4A) and upper extended position (FIG. 4B) of the lifter assembly 10 are defined by upper and lower stop structures, respectively, as described below. The disclosed stop structures predefine the limits of vertical movement of the bellows structure 22, the movable plate 12, and the chuck 14 and the substrates held thereon.

[0024] The upper extended position is determined by contact between the upper travel limiter 70 and an upper stop 72 that is operatively coupled to or integrally formed with the movable plate 12. In some embodiments, the upper travel limiter 70 is integrally formed with the top cap 30 and is part of the lower surface 74 of the top cap 30. In other embodiments, the upper travel limiter 70 is a separate component from the top cap 30 and is operatively coupled to the top cap 30, as shown. For example, the upper travel limiter 70 may be threaded directly onto the top cap 30 or may be coupled to the top cap 30 with a mechanical fastener. The upper travel limiter 70 is positioned to contact the upper stop 72 that extends upward from the upper surface 62 of the movable plate 12. As mentioned above, the upper stop 72 may be integrally formed with the movable plate 12. In embodiments in which upper stop 72 is operatively coupled to movable plate 12, upper stop 72 may have a coupling portion 76 that passes through and threads into movable plate 12, or it may extend completely through movable plate 12 and be coupled to an upper flange 78 located below movable plate 12. In any of the embodiments disclosed herein, the contact between upper travel limiter 70 and upper stop 72 determines the upwardly extended position of movable plate 12.

[0025] The lower retracted position is determined by contact between the lower travel limiting mechanism 80 and a lower stop 82 that is operatively coupled to or integrally formed with the movable plate 12. In the illustrated embodiment, the upper flange 78 includes a body portion 84 that is disposed between the top of the bellows structure 22 and the movable plate 12. The upper flange 78 also includes a downwardly protruding portion, which is the lower stop 82 in the illustrated embodiment. The lower stop 82 is positioned to contact an upwardly protruding portion of the base flange 28, which is the lower travel limiting mechanism 80 in the illustrated embodiment. The contact between the lower stop 82 and the lower travel limiting mechanism 80 determines the lower retracted position of the movable plate 12. Note that in other embodiments, the lower travel limiting mechanism 80 may be a component operatively coupled to the base flange 28 rather than being integrally formed with the base flange 28. Similarly, in other embodiments, the lower stop 82 may be operatively coupled to the upper flange 78 or the movable plate 12.

[0026] Referring now to FIG. 5, a slider assembly 90 replaces the multiple guide shafts 32 and bushing structure 60 shown in FIGS. 4A and 4B. The slider assembly 90 includes multiple slide rails 92 that extend through holes defined by the movable plate 12. Each slide rail 92 is operatively coupled to the base flange 28 and top cap 30. Each slide rail 92 may have a threaded end that engages with a threaded region of the base flange 28 and top cap 30. Alternatively, the slide rails 92 may be coupled to the base flange 28 and top cap 30 by a nut or the like. While the bellows structure 22 provides vertical adjustment of the movable plate 12, chuck 14, and substrate, the slide rails 92 guide their vertical movement and maintain vertical adjustment. The number of slide rails 92 can vary depending on the particular application.

[0027] A plurality of mounting plates 94 corresponding to the number of slide rails 92 are coupled to the upper surface 62 of the movable plate 12. Each mounting plate 94 has a slide member 96 disposed between the corresponding mounting plate 94 and slide rail 92. Thus, the slider assembly 90 ensures smooth, guided movement of the movable plate 12 during up and down movement of the movable plate 12.

[0028] 6A and 6B, simplified schematic diagrams of optical systems 200, 210 comprising the lifter assembly 10 and chuck 14 described above are shown. In one embodiment, the optical systems 200, 210 further include at least one light source 202 (e.g., one or more lasers, one or more broadband light sources, etc.) configured to illuminate an area on the surface of the substrate. In another embodiment, the optical systems 200, 210 include one or more detectors 204 or cameras suitable for detecting light reflected, diffracted, or scattered from the area illuminated by the light source 202. In one embodiment, the one or more detectors 204 may include, but are not limited to, a CCD or TDI-CCD detector, or a photomultiplier detector. Additionally, the optical systems 200, 210 may include a set of optical elements (e.g., illumination optics, collection optics, a beam splitter 206, filters, etc.). The set of optical elements is configured to direct (and focus) illumination from the light source 202 onto the surface of the substrate, and further direct illumination from the surface of the substrate onto an imaging portion of the detector 204 of the optical system 200, 210. For example, the set of optical elements of the optical system 200, 210 may include, but is not limited to, a primary imaging lens suitable for imaging the illuminated area of ​​the substrate onto the focusing portion of the detector 204. Additionally, the image detector 204 may be communicatively coupled to an image processing computer that can identify and store image data acquired from the detector 204.

[0029] The optical systems 200 and 210 disclosed herein may be configured as any optical system known in the art, including, but not limited to, inspection systems, metrology systems, and lithography systems. For example, as shown in FIG. 6A, the optical system 200 may be configured as a bright-field (BF) inspection system. Alternatively, as shown in FIG. 6B, the optical system 210 may be configured as a dark-field (DF) inspection system. Note that the optical configurations shown in FIGS. 6A and 6B are provided for illustrative purposes only and should not be construed as limiting. In a general sense, the optical systems 200 and 210 may include any set of imaging or optical elements suitable for imaging the surface of a substrate.

[0030] The lifter assembly 10 of the presently disclosed embodiments is more compact than other lifting devices. Thus, the lifter assembly 10 can be configured to fit into a smaller overall space and be used with different optical systems. Additionally, the frictionless actuation provided by the bellows structure 22 reduces wear on the lifter assembly components because this frictionless movement accommodates the rotational movement and uneven loads of the angled cylindrical rod.

[0031] While the invention has been described in detail above in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to these disclosed embodiments. The invention can be modified to incorporate any number of changes, alterations, substitutions, or equivalent arrangements not described herein, but which are consistent with the spirit and scope of the invention. Moreover, while various embodiments of the invention have been described, aspects of the invention may include only some of the described embodiments. Also, features, elements, components, or advantages of any one embodiment may be used in any other embodiment. Thus, the invention is not limited by the foregoing description.

Claims

1. 1. A lifter assembly for an optical system, comprising: a chuck including a chuck base and a removable top plate, the removable top plate being one of a plurality of interchangeable removable top plates configured to support a substrate; a movable plate supporting the chuck on an upper surface thereof, the movable plate being vertically adjustable between a lower retracted position and an upper extended position; a bellows structure operatively coupled to the movable plate; a pneumatic system fluidly coupled to the bellows structure for selectively extending and contracting the bellows structure, the pneumatic system extending the bellows structure vertically adjusting the movable plate to the upper, extended position and contracting the bellows structure vertically adjusting the movable plate to the lower, retracted position; and A lifter assembly comprising:

2. 2. The lifter assembly of claim 1, the pneumatic system includes a solenoid having an inlet port, an outlet port, and an exhaust port; the inlet port is fluidly coupled to a source of compressed air for selectively supplying compressed air through the outlet port to an interior chamber of the bellows structure to expand the bellows structure; the exhaust port fluidly coupled to a vacuum generating device to draw compressed air from the interior chamber of the bellows structure and deflate the bellows structure; Lifter assembly.

3. 10. The lifter assembly of claim 1, further comprising: An upper cap; A base flange; a plurality of guide shafts extending through holes in the movable plate to guide vertical adjustment of the movable plate, each guide shaft being operatively coupled to the top cap and the base flange; A lifter assembly comprising:

4. 4. The lifter assembly of claim 3, including a stopper projecting upwardly from the upper surface of the movable plate.

5. 5. The lifter assembly of claim 4, further comprising an upper travel limiting mechanism integrally formed with said upper cap; contact between the upper movement limiting mechanism and the stopper functionally determines the upper extension position of the movable plate; Lifter assembly.

6. 5. The lifter assembly of claim 4, further comprising an upper travel limiting mechanism operatively coupled to said upper cap; contact between the upper movement limiting mechanism and the stopper functionally determines the upper extension position of the movable plate; Lifter assembly.

7. 4. The lifter assembly of claim 3, an upper flange having a body portion disposed between an upper surface of the bellows structure and a lower surface of the movable plate; the upper flange further has a downwardly protruding portion, the downwardly protruding portion being positioned to contact the upwardly protruding portion of the base flange to determine the lower retracted position of the movable plate; Lifter assembly.

8. 4. The lifter assembly of claim 3, Further comprising a plurality of bushing housings corresponding to the number of the plurality of guide shafts; Each of the bushing housings is coupled to the movable plate and has a bushing therein, each bushing concentrically surrounding a corresponding one of the plurality of guide shafts. Lifter assembly.

9. 10. The lifter assembly of claim 1, An upper cap; A base flange; a plurality of slide rails extending through holes in the movable plate to guide vertical adjustment of the movable plate, each slide rail being operatively coupled to the top cap and the base flange; a plurality of mounting plates corresponding to the number of slide rails, each of the mounting plates being coupled to the movable plate and having a slide member provided between each mounting plate and a corresponding slide rail; The lifter assembly further comprises:

10. 10. The lifter assembly of claim 1, The bellows structure is a welded bellows structure. Lifter assembly.

11. 10. The lifter assembly of claim 1, the substrate comprises a semiconductor wafer; Lifter assembly.

12. 1. An optical system comprising: a chuck having a chuck base and a removable top plate for supporting a substrate; a movable plate supporting the chuck on an upper surface thereof, the movable plate being vertically adjustable between a lower retracted position and an upper extended position; a bellows structure operatively coupled to the movable plate, the bellows structure expanding to vertically adjust the movable plate to an upper extended position and the bellows structure contracting to vertically adjust the movable plate to a lower retracted position; a substrate chucking subsystem having an illumination source configured to illuminate one or more portions of the substrate; a detector configured to collect illumination from the illuminated one or more portions of the substrate; An optical system comprising:

13. 13. The optical system of claim 12, wherein the optical system is configured as an inspection tool.

14. 13. The optical system of claim 12, wherein the optical system is configured as a metrology tool.

15. 13. The optical system of claim 12, a pneumatic system fluidly connected to the bellows structure for selectively expanding and contracting the bellows structure; Extending the bellows structure vertically adjusts the movable plate to an upper extended position, and contracting the bellows structure vertically adjusts the movable plate to a lower retracted position. Optical system.

16. 16. The optical system of claim 15, the pneumatic system includes a solenoid having an inlet port, an outlet port, and an exhaust port; the inlet port fluidly coupled to a source of compressed air for selectively supplying compressed air through the outlet port and into the interior chamber of the bellows structure to expand the bellows structure; the exhaust port fluidly coupled to a vacuum generating device to draw compressed air from the interior chamber of the bellows structure and deflate the bellows structure; Optical system.

17. 13. The optical system of claim 12, An upper cap; A base flange; a plurality of guide shafts extending through holes in the movable plate to guide vertical adjustment of the movable plate, each guide shaft being operatively coupled to the top cap and the base flange; The optical system further comprises:

18. 13. The optical system of claim 12, An upper cap; A base flange; a plurality of slide rails extending through holes in the movable plate to guide vertical adjustment of the movable plate, each slide rail being operatively coupled to the top cap and the base flange; a plurality of mounting plates corresponding to the number of slide rails, each of the mounting plates being coupled to the movable plate and having a slide member provided between each of the mounting plates and a corresponding one of the slide rails; The optical system further comprises:

19. A lifter assembly for moving a substrate in a vertical direction, a vacuum chuck configured to support the substrate and hold the substrate by vacuum pressure; a movable plate supporting the vacuum chuck on an upper surface thereof, the movable plate being vertically adjustable between a lower retracted position and an upper extended position; a welded bellows structure operatively coupled to the movable plate, the welded bellows structure expanding to adjust the movable plate to the upper extended position and the welded bellows structure contracting to adjust the movable plate to the lower retracted position; A lifter assembly comprising:

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