Method for inspection, inspection device, and wafer processing system

Abstract

To provide a method for inspection that can adopt more suitable image processing conditions and photographing conditions.SOLUTION: The method for inspection includes: a photographing step for photographing a plurality of wafers W arranged in an x direction by a camera 3; and an inspection step for determining whether the states of the plurality of wafers W are appropriate or inappropriate by performing image processing on images of the plurality of wafers W, When the result of determining the states of the plurality of wafers W in the inspection step shows that the status are inappropriate, the inspection step is repeatedly performed up to M times on the same image under image processing conditions different from those used previously. When the determination result of the M-th inspection shows that the status are inappropriate, the photographing step under photographing conditions different from those used previously and the inspection step up to M times are repeatedly performed up to N times. M and N are integers of at least 2.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to an inspection method, an inspection apparatus, and a wafer processing system. [Background technology]

[0002] Various inspection methods for multiple wafers have been proposed. One example of a conventional inspection method is disclosed in Patent Document 1. The inspection method disclosed in this document inspects multiple wafers by photographing multiple wafers held in a carrier with a camera and performing image processing on the photographed images. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2005-520350 Summary of the Invention [Problem to be solved by the invention]

[0004] In the inspection of a plurality of wafers by image processing, there is a concern that the inspection may become difficult due to a number of factors, such as when the image processing conditions for the image processing are inappropriate or when the photographing conditions are inappropriate.

[0005] The present invention has been devised in light of the above circumstances, and an object of the present invention is to provide an inspection method, an inspection apparatus, and a wafer processing system that are capable of employing more appropriate image processing conditions and photographing conditions. [Means for solving the problem]

[0006] An inspection method provided by a first aspect of the present invention includes a photographing step of photographing, with a camera, a plurality of wafers lined up in a first direction intersecting a vertical direction, and an inspection step of inspecting whether the states of the plurality of wafers are appropriate or inappropriate by image processing the images of the plurality of wafers, wherein if the judgment result of the states of the plurality of wafers in the inspection step is inappropriate, the inspection step is repeated up to M times using the same images under image processing conditions different from the previous time, and if the judgment result the Mth time is inappropriate, the photographing step under photographing conditions different from the previous time and the inspection step up to M times are repeated up to N times (where M and N are integers of 2 or greater).

[0007] In a preferred embodiment of the present invention, in the photographing process, a carrier capable of holding the plurality of wafers and the plurality of wafers are photographed by the camera from above in the vertical direction, the carrier has an opening that penetrates in the vertical direction, and in the inspection process, inspection is performed on images of the plurality of wafers in an inspection area set inside the opening when viewed in the vertical direction.

[0008] In a preferred embodiment of the present invention, the inspection area is divided in the vertical direction and in a second direction intersecting the first direction.

[0009] In a preferred embodiment of the present invention, the method further includes a push-up step in which, prior to the photographing step, a push-up part that has risen through the opening holds the plurality of wafers at a position vertically higher than the position at which the wafers are held by the carrier, and in the photographing step, the plurality of wafers held by the push-up part are photographed, and in the inspection step, the inspection area is set at a position that does not overlap with the push-up part.

[0010] A second aspect of the present invention provides an inspection apparatus that includes a camera that photographs a plurality of wafers lined up in a first direction intersecting the vertical direction from above in the vertical direction, and inspects the plurality of wafers using images from the camera, and that performs an imaging step of photographing the plurality of wafers lined up in the first direction with the camera, and an inspection step of inspecting whether the states of the plurality of wafers are appropriate or inappropriate by image processing the images of the plurality of wafers, and if a determination result of the states of the plurality of wafers in the inspection step is inappropriate, the inspection step is repeated up to M times using the same images under image processing conditions different from the previous time, and if the determination result the Mth time is inappropriate, the imaging step under imaging conditions different from the previous time and the inspection step up to M times are repeated up to N times (where M and N are integers greater than or equal to 2).

[0011] In a preferred embodiment of the present invention, in the photographing process, a carrier capable of holding the plurality of wafers and the plurality of wafers are photographed by the camera from above in the vertical direction, the carrier has an opening that penetrates in the vertical direction, and in the inspection process, inspection is performed on images of the plurality of wafers in an inspection area set inside the opening when viewed in the vertical direction.

[0012] In a preferred embodiment of the present invention, the inspection area is divided in the vertical direction and in a second direction intersecting the first direction.

[0013] In a preferred embodiment of the present invention, the method further includes a push-up step in which, prior to the photographing step, a push-up part that has risen through the opening holds the plurality of wafers at a position vertically higher than the position at which the wafers are held by the carrier, and in the photographing step, the plurality of wafers held by the push-up part are photographed, and in the inspection step, the inspection area is set at a position that does not overlap with the push-up part.

[0014] A wafer processing system provided by a third aspect of the present invention includes the inspection apparatus provided by the second aspect of the present invention and a processing apparatus that performs processing on the plurality of wafers. [Effects of the Invention]

[0015] According to the present invention, more appropriate image processing conditions and shooting conditions can be adopted.

[0016] Other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic plan view showing an inspection apparatus and a wafer processing system according to a first embodiment of the present invention. [Figure 2] 1 is a partial perspective view showing an inspection apparatus and a wafer processing system according to a first embodiment of the present invention. [Figure 3] 1 is a partial front view showing an inspection apparatus and a wafer processing system according to a first embodiment of the present invention. [Figure 4] 1 is a partial plan view showing an inspection apparatus and a wafer processing system according to a first embodiment of the present invention. [Figure 5] FIG. 5 is a partial cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is a partial cross-sectional view taken along line VI-VI in FIG. [Figure 7] 1 is a flowchart illustrating an example of an inspection method according to the present invention. [Figure 8] 5(a) to 5(d) are partially enlarged cross-sectional views showing the push-up process of the present invention. [Figure 9] FIG. 2 is a partial plan view showing an example of an inspection area in an example of an inspection method of the present invention. [Figure 10] 1(a) is an example of an image captured in an example of the inspection method of the present invention, and FIG. 1(b) is an example of the image processing result. [Figure 11]10(a) is another example of an image captured in an example of the inspection method of the present invention, and (b) and (c) are other examples of the image processing results. [Figure 12] 10(a) is yet another example of an image captured in an example of the inspection method of the present invention, and (b) and (c) are yet another example of the image processing results. [Figure 13] 10 is a flowchart showing another example of the inspection method of the present invention. [Figure 14] FIG. 10 is a partial plan view showing another example of an inspection area in the inspection method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] Preferred embodiments of the present invention will now be described in detail with reference to the drawings.

[0019] The terms "first," "second," "third," etc. in the present invention are used merely for identification purposes and are not intended to assign any order to their objects.

[0020] 1 to 6 show an inspection apparatus and a wafer processing system according to a first embodiment of the present invention. As shown in FIG. 1, the wafer processing system α1 of this embodiment includes an inspection apparatus A1, a wafer transfer apparatus B1, and multiple wafer processing apparatuses C1. In this embodiment, the inspection apparatus A1 and the wafer transfer apparatus B1 are configured as a single apparatus. However, the inspection apparatus A1 may be configured as an apparatus separate from the wafer transfer apparatus B1. In the illustrated example, the inspection apparatus A1, the wafer transfer apparatus B1, and the multiple wafer processing apparatuses C1 are each configured as individual apparatus units. By appropriately changing the number and arrangement of the inspection apparatus A1 (wafer transfer apparatus B1) and the multiple wafer processing apparatuses C1, wafer processing systems of different specifications or scales can be efficiently constructed. The wafer processing system α1 is a system that processes multiple wafers W loaded, for example, through a loading / unloading port sb provided in the wafer transfer apparatus B1, and then unloads the processed wafers W. The wafer processing system α1 may also include a transfer device (not shown) for transferring multiple wafers W between the loading / unloading port sb, the inspection device A1, the wafer transfer device B1, and the multiple wafer processing devices C1. The dashed dotted lines in FIG. 1 indicate the movement paths of the multiple wafers transferred by the transfer device.

[0021] In these figures, the z direction corresponds to the vertical direction of the present invention, the x direction corresponds to the first direction of the present invention, and the y direction corresponds to the second direction of the present invention.

[0022] The multiple wafer processing devices C1 are devices that perform the main wafer processing steps in the wafer processing system α1. The types of wafer processing performed in the wafer processing device C1 and the specific configuration of the wafer processing device C1 are not limited in any way. Examples of wafer processing performed in the wafer processing device C1 include RCA cleaning, lift-off, and etching. For example, processing using various chemicals such as SC-1 (ammonia-hydrogen peroxide solution), SC-2 (hydrochloric acid-hydrogen peroxide solution), SPM (sulfuric acid-hydrogen peroxide solution), HF (hydrofluoric acid), BHF (buffered hydrofluoric acid), NMP (N-methyl-2-pyrrolidone), and IPA (isopropyl alcohol (2-propanol)), rinsing (pure water), and drying are performed. Furthermore, the wafer processing system α1 is not limited to a configuration including multiple wafer processing devices C1, and may be configured to include only one wafer processing device C1.

[0023] In the illustrated example, the wafer processing apparatus C1 has a processing tank ca and a cleaning tank cb. The processing tank ca is a tank for storing a processing liquid for performing a predetermined wafer processing. For example, a plurality of wafers W held by a carrier 9 (described later) are inserted into the processing tank ca and immersed in the processing liquid, thereby performing the predetermined wafer processing.

[0024] The cleaning tank cb is a tank for storing, for example, a cleaning liquid for cleaning a plurality of wafers that have been processed in the processing tank ca. For example, the plurality of wafers W that have been processed are inserted into the cleaning tank cb while being held by a carrier 9, and are immersed in the cleaning liquid, thereby cleaning the plurality of wafers W.

[0025] In the wafer processing system α1, a plurality of wafers W are carried in through a carry-in / out port sb while being held by a carrier 9. The carrier 9 holding the plurality of wafers W is placed in a wafer transfer device B1.

[0026] 2 to 6 show the inspection apparatus A1 and wafer transfer apparatus B1. The inspection apparatus A1 may include a camera 3 and a push-up unit 4, and may further include an illumination unit 5 and a control unit 8. The wafer transfer apparatus B1 may include a wafer holding mechanism 2 and a push-up unit 4, and may further include a control unit 8. In order to properly realize the functions of the inspection apparatus A1 and the wafer transfer apparatus B1, the inspection apparatus A1 and the wafer transfer apparatus B1 share a common stand 1. Note that the inspection apparatus A1 and the wafer transfer apparatus B1 are not limited to being configured as a single apparatus; for example, the inspection apparatus A1 and the wafer transfer apparatus B1 may be configured as separate, independent apparatuses. The wafer processing system α1 may also be configured to include the inspection apparatus A1 but not the wafer transfer apparatus B1.

[0027] The pedestal 1 is a structure that supports at least one or all of the wafer holding mechanism 2, camera 3, push-up unit 4, and lighting unit 5. The specific configuration of the pedestal 1 is not limited in any way. In the illustrated example, the pedestal 1 has a main plate portion 11 and a back plate portion 12.

[0028] The main plate 11 is a portion including members along the xy plane, and supports the carrier 9. The back plate 12 is a portion that stands along the yz plane, and supports, for example, the push-up unit 4. The stand 1 may also include portions that support the wafer holding mechanism 2, the camera 3, the lighting unit 5, etc.

[0029] In the illustrated example, the gantry 1 has two main plate portions 11. The two main plate portions 11 are arranged side by side in the y direction. As shown in FIGS. 2 to 5, in the illustrated example, the main plate portion 11 has an opening 111. The opening 111 penetrates the main plate portion 11 in the z direction and is provided to allow the push-up portion 4 to pass through in the z direction. In addition, a plurality of positioning blocks 112 may be attached to the main plate portion 11. The plurality of positioning blocks 112 are used to position the carrier 9 in the x direction and the y direction when the carrier 9 is placed on the main plate portion 11. By having two main plate portions 11, two carriers 9 can be placed on the gantry 1 at the same time.

[0030] The wafer holding mechanism 2 is a mechanism for picking up multiple wafers W from a carrier 9 placed on the main plate portion 11 of the pedestal 1 and transferring them to another carrier 9. As shown in FIGS. 2 and 3, the wafer holding mechanism 2 has, for example, a pair of holding portions 21 and a reciprocating portion 22.

[0031] The pair of holding parts 21 approach the plurality of wafers W held by the carrier 9 from both sides in the y direction and hold the plurality of wafers W. When the plurality of wafers W are held by the pair of holding parts 21, the carrier 9 is released from holding the plurality of wafers W and can exist in an empty state. In this embodiment, the pair of holding parts 21 can hold the plurality of wafers W pushed up in the z direction by the push-up part 4.

[0032] The reciprocating unit 22 supports the pair of holding units 21 and reciprocates in the y direction. The reciprocating unit 22 is configured, for example, by a motor (not shown) as a drive source for realizing the reciprocating motion, and rails extending in the y direction. In the illustrated example, the reciprocating unit 22 is provided with an opening 221. The opening 221 is provided to ensure a field of view for the camera 3 to capture images of multiple wafers W. Note that the wafer holding mechanism 2 may be configured to retreat in the y direction from the field of view of the camera 3 when capturing images with the camera 3. In this case, the reciprocating unit 22 does not necessarily have to be provided with the opening 221.

[0033] The camera 3 is used to capture images used in inspecting multiple wafers W. The camera 3 captures images of the multiple wafers W held in the carrier 9 from above in the z direction. The specific configuration of the camera 3 is not limited in any way, and it may be a so-called area camera or a line camera. If the camera 3 is an area camera, it can capture images of the multiple wafers W held in the carrier 9 in a single capture. If the camera 3 is a line camera, the capture area extends elongatedly in the y direction, for example, and it can capture images of the multiple wafers W by capturing images multiple times while scanning in the x direction. If the camera 3 is a line camera, it has the advantage of suppressing distortion in the image.

[0034] The illumination unit 5 optically assists the camera 3 in capturing images of the multiple wafers W to obtain clearer images. The illumination unit 5 has, for example, multiple light-emitting units (not shown). The light-emitting units may be, for example, LEDs. The illumination conditions of the illumination unit 5 are not limited in any way. The illumination direction, brightness, and color tone of the illumination for the multiple wafers W may be set as appropriate. In the example shown in FIGS. 3 and 9, the illumination unit 5 has a rectangular ring shape surrounding the camera 3 when viewed in the z direction, and is configured to illuminate the multiple wafers W from above in the z direction and from both sides in the x and y directions, i.e., from all four sides.

[0035] The push-up unit 4 is for pushing up the plurality of wafers W held by the carrier 9 placed on the main plate unit 11 upward in the z direction. The specific configuration of the push-up unit 4 is not limited in any way. In this embodiment, as shown in FIGS. 2 to 6, the push-up unit 4 has a support body 40, a central unit 41, a pair of side units 42, and a lifting mechanism 45. In this embodiment, two push-up units 4 are provided corresponding to the two main plate units 11. The two push-up units 4 may have the same configuration or different configurations. In the following description, a case where the two push-up units 4 have the same configuration will be described as an example.

[0036] The support body 40 supports the central portion 41 and the pair of side portions 42 from below in the z direction. The support body 40 is made of, for example, metal or resin.

[0037] The central portion 41 has a shape that extends elongately in the x direction and holds a plurality of wafers W near their centers in the y direction. The central portion 41 has a plurality of grooves 411. The plurality of grooves 411 are aligned at equal pitches in the x direction and each groove is shaped to be able to hold one wafer W. The specific shape of the grooves 411 is not limited in any way. In the illustrated example, the grooves 411 have a shape in which the width in the x direction decreases as they are positioned lower in the z direction, and are, for example, triangular groove shapes.

[0038] The pair of side portions 42 each have a shape that extends elongately in the x direction and are arranged on both sides of the central portion 41 in the y direction. The pair of side portions 42 hold the multiple wafers W in the vicinity of directly below both side portions sandwiching the center in the y direction. The side portions 42 have multiple grooves 421. The multiple grooves 421 are aligned at equal pitches in the x direction and each has a shape that allows for holding one wafer W. The multiple grooves 411 in the central portion 41 and the multiple grooves 421 in the pair of side portions 42 have the same pitch and correspond to each other in position in the x direction. When viewed in the x direction, the grooves 421 are inclined with respect to the y direction and the z direction.

[0039] As shown in FIGS. 4 and 5 , in this embodiment, a reflection-suppressing material 6 is provided at an appropriate location on the push-up portion 4. The reflection-suppressing material 6 is a material that has a lower reflectance for light of a wavelength that contributes to imaging of the target object when photographing multiple wafers W with the camera 3, such as natural light or light from the illumination unit 5, compared to the reflectance of the material of the push-up portion 4. The reflection-suppressing material 6 is typically black or dark gray, but is not limited thereto. An example of a material that can be used to form the reflection-suppressing material 6 is the FineShut Series Extreme / 0.37mm (registered trademark) manufactured by Koyo Orient Japan Co., Ltd. In addition to the configuration in which the reflection-suppressing material 6 is provided on the push-up portion 4, the entire or part of the push-up portion 4 may be formed from a material that is black or dark gray, etc.

[0040] In the illustrated example, the reflection-suppressing material 6 includes a first portion 61 and a second portion 62. The first portion 61 is a part of each of the support body 40, the central portion 41, and the side portion 42, and is provided in a portion located between the plurality of grooves 411 in the central portion 41 and the plurality of grooves 421 in one of the side portions 42 when viewed in the z direction. The side portion 42 is provided on an upright surface of the side portion 42 that is located outward in the y direction from the plurality of grooves 421.

[0041] The lifting mechanism 45 is a mechanism for raising and lowering the support 40 in the z direction. By raising and lowering the support 40, the central portion 41 and the pair of side portions 42 are raised and lowered integrally in the z direction. The specific configuration of the lifting mechanism 45 is not limited in any way, and for example, a linear actuator supported by the back plate portion 12, a guide member for raising and lowering the support 40 along the z direction, or the like may be appropriately adopted. In this embodiment, the lifting mechanism 45 is configured to be able to move and stop the support 40 (the central portion 41 and the pair of side portions 42) at any position including at least two positions.

[0042] The support body 40, the central portion 41, and the pair of side portions 42 are located inside the opening 111 of the main plate portion 11 when viewed in the z direction. This allows the support body 40, the central portion 41, and the pair of side portions 42 to move up and down through the opening 111.

[0043] The control unit 8 controls the operation of each unit of the inspection device A1 and the wafer transfer device B1. The control unit 8 includes, for example, a CPU, a memory unit, a communication unit, an interface unit, etc. as appropriate. The specific configuration of the control unit 8 is not limited in any way. In the example shown in FIG. 3, the control unit 8 includes a main control unit 81 and a camera control unit 82. However, the control unit 8 may be configured with only one control unit that combines the functions of the main control unit 81 and the camera control unit 82, for example. The control unit 8 may also have a communication means for communicating data with, for example, a higher-level control system or a production management PC in a factory where the wafer processing system α1 is installed.

[0044] The main control unit 81 controls, for example, the operations of the wafer holding mechanism 2 and the push-up unit 4. It also sends command signals to the camera control unit and receives information signals from the camera control unit 82. The camera control unit 82 controls the shooting operation of the camera 3, etc. The camera control unit 82 may be configured to be located together with the main control unit 81 at a location separate from the camera 3, or may be configured to be located together with the camera 3 at a location separate from the main control unit 81, or may be configured to be built into the camera 3.

[0045] In the wafer processing system α1 (inspection device A1), multiple wafers W are handled while held on a carrier 9 during most of the processing or steps. The specific configuration of the carrier 9 is not limited as long as it is capable of holding multiple wafers W so that one side of adjacent wafers W faces each other. The material of the carrier 9 is not limited. For example, in the case of a carrier 9 used to transport multiple wafers W from outside the wafer processing system α1 through the loading / unloading port sb to the wafer transfer device B1, the carrier 9 may be made of resin, metal, or the like. On the other hand, the carrier 9 used to transport multiple wafers W in the silicon connecting the wafer transfer device B1 and the multiple wafer processing devices C1 is preferably made of a material that is not altered by the processing liquid used in wafer processing, such as resin, and preferably fluororesin.

[0046] As shown in FIGS. 3 to 6 , the carrier 9 of this embodiment has a case body 91, an opening 92, and two sets of rib rows 93. The case body 91 is open upward in the z direction and has a shape and size that allows it to receive multiple wafers W inserted from above in the z direction. The opening 92 is provided in a lower portion of the case body 91 in the z direction and penetrates the case body 91 in the z direction. As shown in FIG. 4 , the opening 92 has a shape and size that allows it to accommodate the support 40 and a pair of side portions 42 of the push-up unit 4 when the carrier 9 is placed on the main plate 11. The two sets of rib rows 93 are located on both sides of the opening 92 in the y direction. Each of the two sets of rib rows 93 has a plurality of ribs 931. The ribs 931 are arranged at equal pitches in the x direction. The arrangement pitches of the ribs 931 in the two sets of rib rows 93 are equal to each other. The arrangement pitch of the plurality of ribs 931 in the two sets of rib rows 93 may be the same as or an integral multiple of the arrangement pitch of the plurality of grooves 411 and the plurality of grooves 421 in the push-up portion 4 .

[0047] The wafer W is obtained by cutting a single crystal ingot of a semiconductor material such as Si or SiC to a predetermined thickness and can be used, for example, as a material for various semiconductor chips. The wafer W may have an overall circular shape and have an orientation marker portion w1. The orientation marker portion w1 is provided, for example, to indicate the crystal orientation of the wafer W. Examples of the orientation marker portion w1 include a flat portion of the peripheral edge of the wafer W (an orientation flat) and a V-groove-shaped portion (a notch) provided on the peripheral edge of the wafer W. The wafer W shown in FIG. 5 employs an orientation flat as the orientation marker portion w1. In this embodiment, the standard orientation of the multiple wafers W held by the carrier 9 is such that the orientation marker portion w1 faces upward in the z direction and is aligned along the y direction.

[0048] Next, an example of an inspection method using the inspection device A1 will be described below.

[0049] FIG. 7 is a flowchart showing an example of an inspection method using the inspection device A1. The figure shows the number of times n to capture images and the number of times m to process images. First, when the inspection starts, the number of times n to capture images is set to 0 (step S0). Next, the push-up process is performed (step S1). Before the push-up process, the support 40 and the pair of side sections 42 of the push-up unit 4 are located at the first position H1 shown in FIG. 5. At the first position H1, the central section 41 and the pair of side sections 42 are located below and spaced apart from the plurality of wafers W in the z direction. During the push-up process, with the carrier 9 holding the plurality of wafers W mounted on the main plate 11, the lifting mechanism 45 of the push-up unit 4 drives the central section 41 and the pair of side sections 42 from the first position H1 through the openings 111 and 92 to the second position H2. At the second position H2, the push-up unit 4 holds the plurality of wafers W at a position higher than the position where the carrier 9 holds the wafers W in the z direction.

[0050] FIG. 8 is a partially enlarged cross-sectional view showing in more detail the relationship between the multiple wafers W and the push-up unit 4 during the push-up process. In FIG. 8(a), the push-up unit 4 is at the first position H1. The multiple wafers W are held by the carrier 9. The multiple wafers W are individually accommodated between the multiple ribs 931 of the two sets of rib rows 93. The distance between adjacent ribs 931 is greater than the thickness of the wafers W. Therefore, each of the multiple wafers W may be biased to one side or the other in the x direction between the adjacent ribs 931, or may be tilted relative to the y direction or z direction. As a result, the pitches P1, P2, and P3 of the multiple wafers W in FIG. 8(a) tend to be different from one another.

[0051] Next, as shown in Fig. 1(b), the lifting mechanism 45 is driven to raise the central portion 41 and the pair of side portions 42 upward in the z direction, and the plurality of grooves 411 and the plurality of grooves 421 approach the plurality of wafers W. The grooves 411 and 421 have a shape that opens upward in the z direction, and therefore can accommodate the plurality of wafers W arranged at different pitches P1, P2, and P3.

[0052] When the central portion 41 and the pair of side portions 42 are further raised, the grooves 411 and the grooves 421 individually come into contact with the wafers W, as shown in FIG. 1(c). When the central portion 41 and the pair of side portions 42 are further raised, the central portion 41 and the side portions 42 reach the second position H2, as shown in FIG. 1(d). At this time, the wafers W are mainly held by the central portion 41 and the pair of side portions 42, and are hardly or not held at all by the carrier 9. At least in the process from the state shown in FIG. 1(c) to the state shown in FIG. 1(d), the pitches P1, P2, and P3 of the wafers W are more uniform than the pitches P1, P2, and P3 shown in FIG. 1(a).

[0053] Next, the photographing process (step S2) of FIG. 7 is performed. In the photographing process, the camera control unit 82 photographs multiple wafers W using the camera 3 in response to a command from the main control unit 81 of the control unit 8. As described above, multiple types of carriers 9 can be used in the inspection apparatus A1 (wafer processing system α1). For example, as shown in FIG. 3, when carriers 9 of different sizes are mixed, the orientation markers w1 of multiple wafers W can differ from one another by height z1. For this reason, it is preferable that the aperture of the camera 3 be set to an aperture setting that can fully include height z1 in the depth of field. In this embodiment, the depth of field is set to a value that can clearly photograph the entire carrier 9 from its top to its bottom edge so that it can be inspected. As a result, for example, if a wafer W is unintentionally broken, it can be recognized by image processing that the broken pieces remain somewhere on the carrier 9.

[0054] Furthermore, in the photographing process, the number of times of image processing m is set to 0, and the number of times of photographing n is incremented by 1. In other words, when the first photographing process is performed, the number of times of photographing n is set to 1. Note that the notation "n=n+1" in FIG. 7 means that 1 is added to the number of times of photographing n, and is used in a different sense from the mathematical equal sign.

[0055] If the camera 3 is an area camera, it is possible to acquire images of multiple wafers W by taking a single photograph. If the camera 3 is a line camera, it is possible to acquire images of multiple wafers W by taking multiple photographs. For example, multiple wafers W shown in FIG. 10(a) are photographed and their images are obtained.

[0056] Next, the inspection process (step S3) shown in FIG. 7 is performed. In the inspection process, the images of the plurality of wafers W obtained in the photographing process are image-processed to inspect whether the state of the plurality of wafers W is appropriate or inappropriate. Also, in the inspection process, 1 is added to the number of times m of image processing. That is, when the first image processing is performed, the number of times image processing is set to 1. Note that the description "m=m+1" in FIG. 7 means adding 1 to the number of times n of photographing, and is used in a different sense from the mathematical equal sign.

[0057] The inspection process includes, for example, image processing and determination processing. In the image processing, image processing based on various techniques is performed on images of multiple wafers W. The image processing techniques are not limited to these, and examples include shading correction, saturation adjustment, binarization, noise removal, edge extraction, and Sobel processing. These image processing techniques are performed under the corresponding image processing conditions. As a result of this image processing, the images of multiple wafers W shown in FIG. 10(a) are stored as processed images. In particular, in the image processing, so-called preprocessing is performed to remove noise caused by uneven brightness, background reflections, and pattern shadows on patterned wafers W. This is effective in improving the accuracy of inspection of SiC wafers, which are easily transparent to light, and wafers on which patterns are formed.

[0058] In the determination process, it is determined whether the states of the plurality of wafers W are appropriate or inappropriate based on processed images of the plurality of wafers W obtained by image processing. The determination method in the determination process is not limited in any way. In this embodiment, the determination is performed on the images in the inspection area Ar shown in FIG. 9 among the processed images of the plurality of wafers W.

[0059] Unlike the photographing step (step S3), FIG. 9 is a partial plan view viewed from the camera 3 of a carrier 9 that does not yet hold multiple wafers W and is placed on the main plate 11. The inspection area Ar is set inside the opening 92. That is, even if a portion of the carrier 9 is captured in an image of multiple wafers W, that image is not included in the inspection area Ar inside the opening 92. In the illustrated example, the inspection area Ar is divided into a first area ar1 and a second area ar2. The first area ar1 and the second area ar2 are divided in the y direction. The first area ar1 and the second area ar2 are set at positions that do not overlap with the central portion 41 and the side portion 42 of the push-up portion 4. The first area ar1 and the second area ar2 each overlap with the first portion 61 of the reflection suppressing material 6 shown in FIG. 4.

[0060] The image processing in the image processing may be performed on the entire image of the camera 3, or may be performed on only the portion of the image that is included in the inspection area Ar. Alternatively, after performing some image processing on the entire image, other image processing may be performed on only the portion of the image that is included in the inspection area Ar.

[0061] In this example, the determination process is performed on the portions of the processed image data shown in FIG. 10(b) that are included in the first region ar1 and the second region ar2. For example, an image of one wafer W is extracted as two portions: image data Iw1 included in the first region ar1 and image data Iw2 included in the second region ar2. The x- and y-coordinates of the center position O1 of the image data Iw1 are calculated, and the x- and y-coordinates of the center position O2 of the image data Iw2 are calculated. Using the center positions O1 and O2, it can be determined whether the wafer W is in the correct posture and position.

[0062] 10, there are a total of 50 wafers W. This number is the number when the carrier 9 is properly loaded with wafers W. By sequentially calculating the center position O1 of the image data Iw1 and the center position O2 of the image data Iw2, it is possible to determine whether 50 wafers W are present. Furthermore, if the difference in the x-coordinates between the center position O1 and the center position O2 that are thought to correspond to a certain wafer W falls within a predetermined tolerance range, it can be determined that the wafer W is present in the correct orientation without being unduly tilted in the y direction.

[0063] If the presence, position, tilt, etc. of the predetermined number of wafers W satisfy the predetermined criteria, the inspection result is determined to be appropriate (step S4: Yes). In this case, the inspection method is terminated (step S7) without further performing the imaging process (step S2) and the inspection process (step S3). Note that the control unit 8 may reflect lot information about the plurality of wafers W transmitted from a higher-level control system or a production management PC in the factory where the wafer processing system α1 is installed in the judgment criteria. The lot information may include, for example, the number of wafers W, specific details of wafer processing, etc. Also, identification information such as a two-dimensional code may be attached to the carrier 9 transported to the loading / unloading port sb, and the control unit 8 may acquire this identification information and compare it with the lot information.

[0064] On the other hand, in the example shown in FIG. 11, compared to when a plurality of wafers W are fully loaded, the wafer W that should be the second wafer W from one end in the x direction is missing (FIG. 11(a)). In this case, the number of image data Iw1 and image data Iw2 obtained through image processing is less than a predetermined number (for example, 50 pieces each). Therefore, the number of wafers W is insufficient, and the inspection result is determined to be inappropriate (step S4: No). In this case, it is determined whether the number of image processing times m is equal to the maximum number of image processing times M (step S5). The maximum number of image processing times M is an integer equal to or greater than 2. For example, if the maximum number of image processing times M is set to 3, the number of image processing times m is 1, and therefore the number of image processing times m and the maximum number of image processing times M are different (step S5: No). In this case, the inspection process (step S3) is executed again.

[0065] When the second inspection process is performed, the number of image processing times m is incremented by 1 and set to 2. Furthermore, in the (m+1)th inspection process, inspection is performed using the same image as the mth image. The same image means an image derived from the same image captured at a certain timing by the camera 3, and includes images of different sizes being targeted, or images processed under different image processing conditions.

[0066] In the second image processing, image processing is performed under different image processing conditions than in the first image processing. Furthermore, as shown in FIG. 11(c), a newly set inspection area Ar consisting of a first area ar1' and a second area ar2' may be used as the target of judgment. The first area ar1' and the second area ar2' may be set to an area limited to the area that is assumed to have been the basis for the previous judgment that the image was inappropriate.

[0067] For example, even if multiple wafers W are photographed in the appropriate state shown in Fig. 10, the first image processing and determination process may result in an erroneous determination that the wafers are in the state shown in Fig. 11. In the second inspection step, the image processing conditions are changed, so the first region ar1' and the second region ar2' may be subjected to the determination process and determined to be appropriate. In this case (Step S4: Yes), the inspection method ends (Step S7).

[0068] 11, the second inspection process performs image processing and judgment processing on the first region ar1' and the second region ar2', and the inspection result indicates that the state of the wafers W is still inappropriate (step S4: No). Since the number of image processing times m (= 2) is different from the maximum number of image processing times M (= 3) (step S5: No), the inspection process is repeated again (step S3).

[0069] In the third inspection process, image processing is performed under image processing conditions that are further different from the image processing conditions in the first and second inspection processes. If the inspection result of the third inspection process is appropriate (step S4: Yes), the inspection method ends (step S7). On the other hand, if the inspection result of the third inspection process is inappropriate (step S4: No), the number of image processing times m (= 3) is equal to the maximum number of image processing times M (= 3) (step S5: Yes). In this case, the number of photographing times n is compared with the maximum number of photographing times N (step S6). The maximum number of photographing times N is an integer greater than or equal to 2. For example, if the maximum number of photographing times N is set to 3, the number of photographing times n is 1, so the number of photographing times n and the maximum number of photographing times N are different (step S6: No). In this case, the photographing process (step S2) is performed again.

[0070] In the second photographing process, the plurality of wafers W are photographed by the camera 3 under photographing conditions different from those in the first photographing process. The photographing conditions are not limited in any way, and examples thereof include the illumination conditions of the illumination unit 5, the aperture of the camera 3, the shutter speed, etc.

[0071] When a plurality of images of the wafer W are obtained under different photographing conditions (step S2), an inspection process is performed on the images in accordance with steps S3 to S5. That is, the inspection process is repeatedly performed up to the maximum number of image processing times M on the images of the wafer W photographed under different photographing conditions.

[0072] If the inspection results are appropriate in the process of repeating the inspection process up to the maximum number of image processing times M for the image obtained by the second photographing process (step S4; Yes), the inspection method ends. On the other hand, if the inspection results are all inappropriate as a result of repeating the inspection process up to the maximum number of image processing times M (step S5: Yes), the number of photographing times n (= 2) is different from the maximum number of photographing times N (= 3) (step S6: No), so the photographing process is repeated again (step S2).

[0073] In the third photographing step, the camera 3 photographs the plurality of wafers W under photographing conditions different from those in the first and second photographing steps. When images of the plurality of wafers W under different photographing conditions are obtained (step S2), the inspection step is repeatedly performed on the images in accordance with steps S3 to S5 up to the maximum number of image processing times M. If the inspection results are appropriate in the process of repeating the inspection step up to the maximum number of image processing times M for the images obtained in the third photographing step (step S4: Yes), the inspection method ends. On the other hand, if the inspection results are all inappropriate as a result of repeating the inspection step up to the maximum number of image processing times M (step S5: Yes), the number of photographs n (= 3) is equal to the maximum number of photographs N (= 3) (step S6: Yes), and therefore the inspection method ends. In this case, the conclusion of the inspection method is that the state of the plurality of wafers W is inappropriate.

[0074] FIG. 12 shows another example in which the state of multiple wafers W is inappropriate. As shown in FIG. 12(a), the second wafer W from one end of the multiple wafers W in the x direction is accommodated in a rib 931 of one rib row 93 that does not correspond to a rib 931 of the other rib row 93, and is tilted with respect to the y direction. In this case, the difference in the x coordinates between the center position O1 of the image data Iw1 and the center position O2 of the image data Iw2 in FIG. 12(b) may exceed a predetermined tolerance. Therefore, in the inspection method of FIG. 7, even if the inspection process is repeated the maximum number of image processing times M for any image obtained by the photographing process (step S2), the inspection result will be inappropriate (step S4: No). Also, even if the photographing process is repeated the maximum number of photographing times N, the inspection result will still be inappropriate.

[0075] Furthermore, an example of an inappropriate state of multiple wafers W is when one of the image data Iw1 and Iw2 cannot be extracted due to a missing portion of one of the wafers W. Alternatively, an example is when two wafers W are erroneously inserted between adjacent ribs 931, resulting in the difference in the x-coordinate of the center position O1 of the image data Iw1 in the x-direction being too small below a predetermined tolerance. Furthermore, the area of ​​the image data Iw1 may be used to inspect whether a wafer W is missing, whether two wafers W are erroneously inserted between adjacent ribs 931, etc.

[0076] Next, the operation of the inspection method, inspection device, and wafer processing system of this embodiment will be described.

[0077] 7, in the inspection method of this embodiment, the photographing process under different photographing conditions is repeated up to a maximum of N photographing times, and the inspection process under different image processing conditions is repeated up to a maximum of M image processing times for the images obtained in each photographing process. This makes it possible to adopt more appropriate image processing conditions and photographing conditions, and prevents the inspection results from being inappropriate even when multiple wafers W are in an appropriate state due to insufficient settings of the photographing conditions or image processing conditions.

[0078] 9 to 12, the inspection area Ar is set inside the opening 92. This makes it possible to prevent the image of the carrier 9 from becoming noise or the like and adversely affecting the inspection results in the image processing and determination processing in the inspection process.

[0079] By dividing the inspection area Ar into a first area ar1 and a second area ar2 in the y direction, it is possible to extract and inspect portions of a wafer W that are separated in the y direction. If these areas include an orientation marker w1, such as an orientation flat, a clearer image can be obtained. Alternatively, defects such as chipping or tilt of the wafer W can be properly detected by inspecting the first area ar1 and the second area ar2. Furthermore, by appropriately setting the first area ar1 and the second area ar2, it is also possible to inspect areas that do not include an orientation flat, for example, as the first area ar1 and the second area ar2.

[0080] The first region ar1 and the second region ar2 are set at positions that do not overlap with the central portion 41 and the pair of side portions 42 of the push-up portion 4. This makes it possible to prevent the plurality of grooves 411 and the plurality of grooves 421 from becoming noise in the inspection process of the plurality of wafers W.

[0081] According to this embodiment, as shown in Fig. 5, the camera 3 captures an image of the multiple wafers W held by the push-up unit 4 at the second position H2. This results in the multiple wafers W being captured in a state where they are separated upward in the z direction from the carrier 9. This prevents the image of the carrier 9 from being clearly visible in the image of the multiple wafers W. This reduces the influence of the carrier 9 on the inspection of the multiple wafers W.

[0082] As shown in FIG. 8 , the pitches P1, P2, and P3 of the multiple wafers W held by the push-up unit 4 at the second position H2 are more uniform than the pitches P1, P2, and P3 of the multiple wafers W held by the carrier 9. This improves the accuracy of inspection using images of the multiple wafers W, preventing inspection results from differing from the actual state of the multiple wafers W. In particular, in recent years, a method has begun to be adopted in which the pitch of the multiple wafers W in the carrier 9 is set to, for example, about half of the conventional pitch, thereby holding twice the number of multiple wafers W in one carrier 9, thereby more efficiently processing multiple wafers W. There is also a trend toward using thinner wafers W. In light of this industry trend, this embodiment enables more preferable inspection of wafers W.

[0083] 13 and 14 show modified examples or other embodiments of the present invention. In these figures, elements that are the same as or similar to those in the above-described embodiment are given the same reference numerals. Furthermore, the configurations of the various parts in each modified example and each embodiment can be appropriately combined with each other as long as no technical contradiction occurs.

[0084] 13 shows another example of the inspection method of the present invention. This example does not include the push-up step (step S1) in the above-described inspection method. That is, in this example, multiple wafers W are held on a carrier 9 and photographed by a camera 3, and the inspection step is performed using the image. For example, this configuration can be used in cases where the image of the carrier 9 does not cause significant noise in the image of the multiple wafers W even when the multiple wafers W are held on the carrier 9, or in cases where the pitch between the multiple wafers W is relatively uniform when the multiple wafers W are held on the carrier 9.

[0085] 14 shows another example of the inspection area Ar. In this example, the inspection area Ar is set inside the opening 92, but is set as a single area and is not divided in the y direction. Furthermore, the inspection area Ar can include the central portion 41 and a pair of side portions 42 of the push-up portion 4.

[0086] Even in this example, it is possible to prevent the carrier 9 from appearing in the image of the multiple wafers W, and to prevent the carrier 9 from adversely affecting the inspection of the multiple wafers W. As can be seen from this example, the inspection area Ar can be set in various ways.

[0087] The inspection method according to the present invention is not limited to the above-described embodiment, and the specific configuration of the inspection method according to the present invention can be freely modified in various ways. [Explanation of symbols]

[0088] A1: Inspection equipment α1: Wafer processing system 1: Stand 2: Wafer holding mechanism 3: Camera 4: Push-up part 5: Lighting section 6:Reflection suppressing material 8: Control section 9: Career 11: Main plate part 12: Back plate part 21: Holding part 22: Reciprocating part 40:Support 41: Central part 42: Lateral part 45: Lifting mechanism 61: Part 1 62: Part 2 81: Main control unit 82: Camera control unit 91: Case body 92: Opening 93: Rib row 111: Opening 112: Positioning block 221: Opening 411,421: Groove 931: Rib Ar: inspection area B1: Wafer transfer device C1: Wafer processing equipment H1 :1st position H2: 2nd position Iw1, Iw2: Image data M: Maximum number of image processing times N: Maximum number of shots O1,O2: Center position P1, P2, P3: Pitch W: Wafer ar1,ar1': 1st area ar2,ar2': 2nd area ca: Treatment tank cb: cleaning tank m: Number of image processing times n: Number of shots sa: exterior wall sb: Loading / unloading exit w1: Orientation indicator z1: height

Claims

1. an imaging step of imaging a plurality of wafers arranged in a first direction intersecting with a vertical direction with a camera; an inspection step of inspecting whether the state of the plurality of wafers is appropriate or inappropriate by image processing of the images of the plurality of wafers, If the determination result of the state of the plurality of wafers in the inspection process is inappropriate, the inspection process is repeated up to M times using the same image as the target under image processing conditions different from the previous time; When the Mth determination result is inappropriate, the photographing step is repeated up to N times under photographing conditions different from those used previously and the inspection step is repeated up to M times. (where M and N are integers of 2 or greater.)

2. In the photographing step, a carrier capable of holding the plurality of wafers and the plurality of wafers are photographed by the camera from above in the vertical direction; the carrier has an opening passing through in the vertical direction, 2. The inspection method according to claim 1, wherein the inspection step inspects images of the plurality of wafers in an inspection area set inside the opening when viewed in the vertical direction.

3. The inspection method according to claim 2 , wherein the inspection area is divided in a second direction intersecting the vertical direction and the first direction.

4. a push-up step of holding the plurality of wafers at a position vertically above a position at which the wafers are held by the carrier by a push-up unit that has risen through the opening before the photographing step, In the photographing step, photographs of the plurality of wafers held by the push-up unit are taken, The inspection method according to claim 3 , wherein in the inspection step, the inspection area is set at a position that does not overlap with the push-up portion.

5. An inspection apparatus including a camera that photographs a plurality of wafers arranged in a first direction intersecting a vertical direction from above the vertical direction, and inspects the plurality of wafers using an image captured by the camera, an imaging step of imaging the plurality of wafers arranged in the first direction with the camera; an inspection step of inspecting whether the state of the plurality of wafers is appropriate or inappropriate by image processing of the images of the plurality of wafers; If the determination result of the state of the plurality of wafers in the inspection process is inappropriate, the inspection process is repeated up to M times using the same image as the target under image processing conditions different from the previous time; If the Mth determination result is inappropriate, the inspection device repeats the photographing step under photographing conditions different from those used previously and the inspection step up to M times, up to N times. (where M and N are integers of 2 or greater.)

6. In the photographing step, a carrier capable of holding the plurality of wafers and the plurality of wafers are photographed by the camera from above in the vertical direction; the carrier has an opening passing through in the vertical direction, 6. The inspection device according to claim 5, wherein the inspection step inspects images of the plurality of wafers in an inspection area set inside the opening when viewed in the vertical direction.

7. The inspection device according to claim 6 , wherein the inspection area is divided in the vertical direction and in a second direction intersecting the first direction.

8. a push-up step of holding the plurality of wafers at a position vertically above a position at which the wafers are held by the carrier by a push-up unit that has risen through the opening before the photographing step, In the photographing step, photographs of the plurality of wafers held by the push-up unit are taken, The inspection device according to claim 7 , wherein in the inspection step, the inspection area is set at a position that does not overlap with the push-up portion.

9. An inspection device according to any one of claims 5 to 8; a processing device that processes the plurality of wafers.

Images