KR20150002026U - Flat substrate inspection system - Google Patents

Abstract

The inspection system of the present invention includes a table configured to receive a flat substrate and carry it through the scan area in the scan direction. A scan bridge is mounted on the scan area, and the scan bridge includes two or more parallel rails extending between the scan areas in the direction of the rail across the scan direction. The first plurality of mounts are tightened to the rails at their respective positions spaced apart by a selected distance along each rail and the position and spacing are adjustable by sliding the mount along the rails. A second plurality of optical inspection modules are each secured to the mount at their respective positions to capture an image of their respective areas of the flat substrate within the scan area.

Description

[0001] FLAT SUBSTRATE INSPECTION SYSTEM [0002]

This invention relates generally to automated optical inspection, and more particularly to inspection of flat large substrates.

Various systems for automated optical inspection (AOI) of patterned flat substrates, such as flat panel displays, are known in the art. One example of such a system is Orbotech Ltd., Yavne, Israel. Supervision AOI System.

Systems of this type are also described in the patent literature. For example, U.S. Patent No. 7,386,161 describes a simultaneous low resolution / high resolution parallel scanning system and method for use in a scanning process of an inspection system for a planar object, such as a large plate used in a panel display. Low-resolution defect detection effectively overlaps and parallelizes high-resolution defect review and classification stages that automatically recognize and analyze defects. The system is particularly useful for detecting pattern defects on a large glass plate deposited with an integrated circuit to form an LCD flat panel display.

As another example, U.S. Patent Application Publication No. 2010/0309308 describes an apparatus for inspection comprising an imaging assembly including a plurality of cameras, wherein the plurality of cameras are mounted at different locations in the imaging assembly, To capture an image of each of them. The motion assembly is configured to move at least one of the imaging assembly and the sample so that the imaging assembly can scan the sample. An image processor is connected to receive and process the image captured by the camera to locate the defect in the sample with a more precise positional accuracy than the position tolerance of the imaging assembly.

Embodiments of the present invention provide an inspection system that scans a flat substrate in parallel using a plurality of optical inspection modules.

Accordingly, an inspection system according to an embodiment of the present invention is provided, wherein the inspection system comprises a table configured to receive a flat substrate and to carry it through a scan area in a scan direction. A scan bridge is mounted on the scan area, and the scan bridge includes two or more parallel rails extending between the scan areas in the direction of the rail across the scan direction. The first plurality of mounts are tightened to the rails at their respective positions spaced apart by a selected distance along each rail and the position and spacing are adjustable by sliding the mount along the rails. A second plurality of optical inspection modules are each secured to the mount at their respective positions to capture an image of their respective areas of the flat substrate within the scan area.

In the disclosed embodiment, the two or more parallel rails include at least first and second rails, and the position of each of the mounts on the first rail is transverse to the position of the respective one of the mounts on the second rail They are staggered. Wherein the two or more parallel rails include a third rail and the position of each of the mounts on the third rail is transversely staggered with respect to a position of the respective one of the mounts on the first and second rails. Additionally or alternatively, the scan bridge may include a first staggered structure in which the mounts on the first and second rails are spaced apart by a first spacing, and a second staggered structure on which the mounts on the first and second rails are spaced at a second spacing And may have a second staggered structure spaced apart.

In some embodiments, the scan bridge includes a mounting pin, each mounting pin having one of the mounts secured to a corresponding one of the optical inspection modules to secure one of the optical inspection modules to one of the mounts at the predefined location . The system may comprise an adjustment jig, which is adapted to engage a corresponding pair of mounting pins of the mount on one of the rails, and at a selected spacing when the mount is tightened to one of the rails And a pair of sockets configured to retain the mating mounting pins.

Typically, the scan bridge includes a motion assembly, wherein the motion assembly is configured to adjust at least one of a lateral position and a height of the scan bridge relative to the flat substrate.

In a disclosed embodiment, the system includes at least one video bridge mounted on the table in a parallel arrangement to the scan bridge, the video bridge being adapted to capture an image outside the scan area of selected areas of the flat substrate And one or more cameras movable in the lateral direction. The at least one video bridge may include two video bridges mounted on a table on opposite sides of the respective ones of the scan bridges.

Additionally or alternatively, the system includes a plurality of backlight illumination sources, wherein the plurality of backlight illumination sources are mounted under the surface of the table to be self-aligned with the optical inspection module, As shown in FIG.

The present invention will be more readily understood from the following detailed description of an embodiment which is presented in conjunction with the drawings.

1 is a schematic perspective view of an inspection system according to an embodiment of the present invention;
FIG. 2 is a schematic perspective view of a scan bridge used in an inspection system according to an embodiment of the present invention; FIG.
FIG. 3 is a schematic side view of an optical inspection module according to an embodiment of the present invention; FIG.
Figure 4 is a schematic detail view of an optical inspection module mounted on a scan bridge, according to one embodiment of the present invention;
5 is a schematic perspective view of a jig for adjusting the position of an optical inspection module in a scan bridge, according to an embodiment of the present invention;
Figures 6A-6C are schematic top views of scan bridges showing different development structures of optical inspection modules within a scan bridge, according to one embodiment of the present invention;
Figure 7 is a schematic top view of an inspection system, in accordance with another embodiment of the present invention;
Figure 8 is a schematic cross-sectional view illustrating the details of the inspection system, in accordance with one embodiment of the present invention;

The aforementioned U.S. Patent Application Publication No. 2010/0309308 describes an imaging assembly in which a plurality of cameras are arranged at respective positions along at least first and second rows in a direction transverse to the scan direction, The positions of the respective ones of the cameras are transversely staggered with respect to the positions of the cameras in the second row. This arrangement is useful for reaching high sampling densities during inspection of the substrate.

Embodiments of the present invention described herein provide an adjustable array of optical inspection modules to an inspection system that allows the scan density to vary according to application requirements. In the disclosed embodiment, the inspection system includes a table for receiving and transporting a flat substrate in a predetermined direction (referred to as the scanning direction) and a scan bridge mounted over a predetermined area of the substrate on the table. The scan bridge includes two or more parallel rails extending between the scan areas in a direction transverse to the scan direction. A plurality of mounts are tightened to the rails at their respective positions, spaced apart by a selected distance along each rail. The optical inspection module is fixed to the mount to capture an image of the respective area of the substrate within the scan area. The position and spacing of the mount, and thus of the optical inspection module, and of the area they are imaging, is adjustable by sliding the mount along the rail.

Typically (but not necessarily), the positions of the mounts on the different rails are transversely staggered relative to each other. The scanning bridge supports a series of different staggered structures, of which the distance between the mount and the optical inspection module can vary by a factor of two or more. The lateral position and height of the scan bridge relative to the flat substrate may also be variable. In this way, different levels of resolution and scan rate / time can be supported.

1 is a schematic perspective view of an inspection system 20, according to one embodiment of the present invention. System 20 is particularly well suited for automated inspection of large, flat substrates, such as flat panel displays, and can be used in a variety of different lighting modes including darkfield, brightfield, color illumination, and backlighting, either alone or in combination, Can be used to observe and detect defects in a pattern formed on a substrate at a resolution. Different lighting systems may be controlled individually to enable any desired combination of illumination modes.

A substrate 22 to be inspected is placed on the table 24, and the table carries the substrate through the scan area under the scan bridge 32. The table 24 includes a chassis 26 that supports a set of parallel hollow bars 28 that produce an air cushion and allow the substrate 22 to float on such air cushion with minimal friction and vibration . For this purpose, the bar 28 is typically pressurized with air and emits air through an opening below the substrate 22 (not shown). One or more grippers 30 hold the substrate 22 and advance the substrate 22 along the table in the scan direction, i.e., from the lower left to the upper right. Although the gripper 30 is shown in the figures as being located on the side of the table 28, other types of grippers or conveyors may be used to hold and move the substrate 22. Alternatively or additionally, the scan bridge 32 may be carried on the substrate 22.

The scan bridge (32) includes a plurality of optical inspection modules (34) arranged in groups among the scan bridges in a direction transverse to the scan direction. The optical inspection module and its arrangement in the scan bridge will be described in detail with reference to the following drawings. The scan bridge 32 may also include a motion assembly 35 that adjusts the height of the scan bridge relative to the substrate 22. In this way, the magnitude of the field of view (FOV) of the optical inspection module 34 can be changed (typically in conjunction with adjustment of its optical power and focus). Alternatively or additionally, the height of the optical inspection module 34 may be individually adjustable. The motion assembly 35 can be configured to adjust the lateral position of the optical inspection module 34 on the scan bridge 32. In addition,

The system 20 may further include a video bridge 36 mounted on the table 24 in an arrangement parallel to the scan bridge 32. The video bridge 36 includes one or more cameras (not shown) that are movable in a lateral direction to capture an image of a selected area of the substrate 22. The video camera of the video bridge 36 may be controlled to capture a high resolution image of the area of the substrate 22, for example, where a suspected defect is identified by the optical inspection module 34 in the scan bridge 32 And may include a high resolution video microscope. Optionally, the system 20 may include two or more parallel-to-serial converters arranged in groups along the scan direction so as to have one video bridge on either side of the scan bridge 32, Video bridge.

One or more computerized controllers 38 may be coupled to other components of the system 20 to control their operation and process the data they output. The controller 38 typically controls the operation of the table 24 including the gripper 30, the scan bridge 32 and the video bridge 36. The controller 38 also receives output data from the optical inspection module 340 and from the camera in the video bridge 36 and can process the data to detect defects and features on the substrate 22, Provide commands to appropriate system elements and generate audit reports and alarms.

2 is a schematic perspective view illustrating the details of the scan bridge 32, in accordance with one embodiment of the present invention. The scan bridge 32 includes a frame 40 and two or more parallel rails 42 extend between the frames in a direction transverse to the scanning direction of the system 20. [ The mounts 44 for the optical inspection module 34 are fastened to the rails 42 at their respective positions spaced along the rails. The position of the mount 44 and the spacing therebetween are adjustable by sliding the mount along the rails. The optical inspection module 34 is fixed to a respective mount 44 and thus captures images of different areas of the substrate within the scan area.

Typically, the mounts 44 are first placed and tightened in desired locations, and the optical inspection module 4 is then tightened to their respective mounts. Figure 2 illustrates the scan bridge 32 at the stage where the optical inspection module 34 is in turn fastened to the mount after the mount 44 is in place. In the illustrated structure, the optical inspection module 34 is tightly spaced together along two of the rails 42, and the third rail is empty. Using a wide range of different deployment techniques, modules can be deployed on one, two, or all three rails at different intervals. Some of these techniques are shown in Figures 6A-6C and are described below with reference to them.

3 is a schematic side view of optical inspection module 34, in accordance with one embodiment of the present invention. The illumination assembly 50 generates light and directs it to the substrate 22. Typically, the illumination assembly comprises at least one light source, such as a halogen lamp, a light emitting diode (LED), or a laser. As noted above, the illumination assembly 50 can typically be configured for bright field or dark field illumination, using spectrally-selected light, in a narrow wavelength band or in a light wavelength band, with pulsed or continuous operation . (As used in the description and claims, the term "light" refers to any kind of optical radiation, including any or all of the infrared, visible, and ultraviolet radiation). Alternatively or additionally, (Not shown) may be disposed beneath the surface of the table 24 to provide backlighting of the substrate 22. The objective optical system 52 collects light from the substrate and focuses the light on the image sensor 45, and the image sensor outputs image data to the controller 38. The image sensor 54 may comprise a CCD or CMOS matrix array of sensor elements, or alternatively may comprise a linear array or time delay integration (TDI) sensor. The components of the optical inspection module 34 are preferably housed in a protective case 56 shown here in cross-section.

The optical inspection module 34 may be similar in some aspects of structure and function as compared to the inspection camera described in the aforementioned U.S. Patent Application Publication No. 2010/0309308, To the design and operation of the microprocessor 34, with only minor modifications to the required portion.

The optical inspection module 34 includes a mounting bracket 58 for fastening the optical inspection module to the mount 44. The mounting pin 60 is engaged with the socket in the mount 44 and the corresponding socket in the bracket 58 to move the optical inspection module 34 to the mount 44 in the precise compartment position Can be fixed.

Figure 4 is a schematic detail showing the mounting of the optical inspection module 34 on the scan bridge 32, in accordance with one embodiment of the present invention. The mount 44 slides along the rails 42 to the desired position and is tightened in place by tightening the screws 62 in this position. The mount 44 is fitted with the pin 60 for placement of the bracket 58, as previously described. Thus, the optical inspection module 34 is disposed on the mount 44 by fitting the bracket 58 over the pin 60. [ The optical inspection module is then clamped in place by inserting the screws 66 through the bracket 58 into the threaded socket 64 in the mount 44.

In an alternative embodiment (not shown in the drawings), the optical inspection module is first fastened to its respective mount, and then the mount is positioned and tightened in place on the rail.

5 is a schematic perspective view of a jig 70 for positional adjustment of the optical inspection module 34 in the scan bridge 32, in accordance with one embodiment of the present invention. The jig 70 includes a pair of holders 72 which allow a respective width of the socket 74 to engage with a mounting pin 60 of a corresponding pair of mounts 44 on one of the rails 42 Accept. The holder 72 is connected to a spacing bar 76 by a respective clip 78 which can be loosened to adjust the distance between the holders, And is tightened to fix the holder. Such a distance may be smaller or larger than that shown in Fig. 5, depending on the selected interval between the optical inspection modules 34. Fig.

During deployment of the mount 44, the socket 74 is fitted over the mounting pin 60 in a pair of adjacent mounts 44 on the rail 42, Hold the mounting pins at selected intervals when tightened. This process is repeated over the length of each rail to which the optical inspection module is to be mounted.

Figures 6A-6C are schematic top views of scan bridges 32 showing the deployment structure of different ones of the optical inspection modules 34 in the scan bridge, according to one embodiment of the present invention. As the substrate 22 is carried under the scan bridge 32, the image captured by each optical inspection module covers the respective swath of the substrate along the scan direction. The height of the optical elements of the optical inspection module 34 and the height of the scan bridge 32 are adjusted relative to the module spacing so that they are captured (typically captured by an optical inspection module mounted on a different rail 42) Adjacent traces are slightly overlapped at the edges. In this way, the traces can cover the entire area of the substrate 22 in a single pass through the scan area.

In FIGS. 6A and 6B, the optical inspection module 34 is arranged in groups along two of the rails 42, and the mounts 44 on each rail are positioned in a transverse staggered manner relative to the mounts on the other rails. (Formally speaking, the phrase "staggered" used in the detailed description of the design and claims is intended to mean that the position of each of the modules 34 in the transverse direction along one of the rails is between the positions of their respective modules on the other rail Quot;). However, the modules 34 in the structure of FIG. 6A are spaced about twice the distance of the module of FIG. 6B. Depending on the application requirements, by means of appropriate adjustment of the module positions, various intermediate intervals and narrower and wider intervals are also possible.

In some embodiments, the arrangement of the optical modules 34 may be such that the entire width of the inspected substrate 22 is covered (with or without overlap between viewing ranges of the optical modules) so that one substrate can be fully inspected in one pass . In another embodiment, the arrangement of the optical modules 34 is such that only a portion (e.g., the right side) of the width of the inspected substrate 22 is covered (with or without overlap between the viewing ranges of the optical modules) So that more passes than are required for scanning. This latter kind of embodiment may be required when the number of available optical modules 340 is not sufficient to cover the entire width of the test substrate to be inspected.

In another embodiment, a "zebra-scan" structure is used and the spacing between the optical modules 34 is such that individual stripes are scanned along the substrate 22 and stripe- . In this embodiment, a plurality of interlaced scans are performed to cover the entire width of the inspected substrate.

In FIG. 6C, the optical inspection module 34 also forms a group along the third rail 42. In this case, the position of each of the mounts on the third rail is transversely staggered with respect to the position of each of the mounts on the remaining two rails. In this manner, the misalignment of the optical inspection module 34 adjusts the scan bridge 32 and the module 34 such that the optical inspection module captures high-resolution, narrow and closely spaced image traces. Due to the physical width of the optical inspection module itself, this close spacing can not be realized if the optical inspection modules 34 are arranged in a single row without staggering.

In the illustrated embodiment, mount 44 and optical inspection module 34 are grouped over the entire width of scan bridge 32, but in an alternative embodiment (not shown in the drawings) It may be installed only over a portion of the width of the scan bridge for use in inspecting a narrow area of a wide substrate or a narrow substrate. Other arrangements of the optical inspection module 34 on the rail 42 will be apparent to those skilled in the art and are considered to be within the scope of the present invention.

7 is a schematic top view of an inspection system 80, in accordance with another embodiment of the present invention. The system 80 of the present embodiment includes video bridges 82 and 84 mounted on the table 24 on opposite sides of the scan bridge 32 in a parallel arrangement relative to the scan bridge. Each video bridge 82,84 includes one or more cameras 86 that are movable in a lateral direction to capture an image of a selected area of the substrate 22. [ The camera 86 is capable of capturing a high resolution image of the area of the substrate 22 where suspected defects are identified by the optical inspection module 34 in the scan bridge 32. For example, Scope. ≪ / RTI > In another form, the system 80 is similar in design and operational aspects to the system 20 described above.

8 is a schematic cross-sectional view showing the details of the inspection system 20 or 80, according to one embodiment of the present invention. In this embodiment, a backlight illumination source 90 is mounted below the surface of the table 24 that supports the substrate 22. Each illumination source 90 is aligned with a corresponding optical inspection module 34 and a region of the substrate 22 (not shown in this figure) is illuminated through a gap between the bars 28 of the table 24, do. The illumination source 90 may be tilted to provide a bright field or dark field backlight of the substrate. The number and location of the illumination sources 90 between the gaps between the bars 28 may be similarly shifted to accommodate the shift of the structure of the modules 34 in the scan bridge 32, as previously described.

Accordingly, the embodiments described above are cited by way of example and the present invention is not limited to the specifically described and illustrated hereinbefore. Rather, the scope of the present invention includes combinations and subcombinations of the various features described above, and variations and modifications which will appear to those skilled in the art after reading the foregoing description and which are not disclosed in the known art.

Claims (10)

A table configured to receive a flat substrate and carry it through a scan area in a scanning direction;
And a scan bridge mounted on the scan area,
The scan bridge includes:
Two or more parallel rails extending between the scan regions in a rail direction across the scan direction,
A first plurality of mounts fastened to the rails at respective positions spaced apart by a selected distance along each rail, the position and spacing being adjustable by sliding the mount along the rails;
And a second plurality of optical inspection modules each secured to the mount at respective locations to capture an image of their respective areas of the flat substrate within the scan area
Inspection system. The method according to claim 1,
Wherein the two or more parallel rails include at least a first and a second rails and wherein the position of each of the mounts on the first rail is transversely offset relative to a position of the respective one of the mounts on the second rail
Inspection system. 3. The method of claim 2,
Wherein the two or more parallel rails comprise a third rail and the position of each of the mounts on the third rail is transversely offset relative to the position of the respective one of the mounts on the first and second rails
Inspection system. 3. The method of claim 2,
Wherein the scan bridge comprises a first staggered structure in which the mounts on the first and second rails are spaced apart by a first spacing and a second staggered structure on which the mounts on the first and second rails are spaced apart by a second spacing that is twice the first spacing, Having a staggered structure
Inspection system. The method according to claim 1,
The scan bridge includes a mounting pin and each mounting pin engages one of the mounts with a corresponding one of the optical inspection modules to secure one of the optical inspection modules to one of the mounts in the predefined position
Inspection system. 6. The method of claim 5,
Comprising an adjustment jig,
The adjustment jig has a pair of sockets configured to engage corresponding pairs of mounting pins of the mount on one of the rails and to hold the mounting pins engaged at selected intervals when the mount is tightened to one of the rails Have
Inspection system. The method according to claim 1,
The scan bridge including a motion assembly configured to adjust at least one of a lateral position and a height of the scan bridge relative to the flat substrate,
Inspection system. The method according to claim 1,
And at least one video bridge mounted on the table in a parallel arrangement to the scan bridge,
Wherein the video bridge includes one or more cameras that are laterally movable to capture an image outside the scan area of selected areas of the flat substrate
Inspection system. 9. The method of claim 8,
Wherein the at least one video bridge comprises two video bridges mounted on a table on opposite sides of the respective one of the scan bridges,
Inspection system. The method according to claim 1,
A plurality of backlight illumination sources,
Wherein the plurality of backlight illumination sources
Mounted under the surface of the table so as to be self-aligned with the optical inspection module,
And backlighting the substrate through the gap in the table
Inspection system.

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