TW202215591A - Wafer chuck inspection system - Google Patents

Abstract

The invention discloses a wafer chuck inspection system used for inspecting a wafer chuck. The wafer chuck is defined with a supporting surface, and the supporting surface comprises a first inspection area and a second inspection area. The wafer chuck inspection system comprises a first camera module and a second camera module. The first camera module is disposed on a first side of the wafer chuck for photographing the second inspection area. The second camera module is arranged on a second side of the wafer chuck for photographing the first inspection area. The wafer chuck is defined with a center line, the first side and the second side are located on both sides of the center line, and the first inspection area and the second inspection area are located on both sides of the center line.

Description

Wafer chuck inspection system

The present invention relates to a wafer chuck detection system, in particular to a wafer chuck detection system using a plurality of camera modules.

Wafer chucks are used to carry wafers for various processes, and are often used in various semiconductor machines. Since the semiconductor manufacturing process requires a high degree of precision, if there is foreign matter, contamination or damage on the surface of the wafer chuck, it is likely to affect the yield of the subsequent process. Therefore, the industry needs to check the condition of the wafer chuck frequently. Compared with manually inspecting the wafer chuck, it is better to use a camera to photograph the surface of the wafer chuck, and to judge the condition of the wafer chuck through image analysis. However, since the functions of the existing semiconductor machines are very clear, such as for etching, epitaxy, etc., there is often no extra space to set up the camera, so it is difficult to have the function of inspecting the wafer chuck at the same time. To remove the wafer chuck from the semiconductor tool for inspection means interrupting the process and reducing production efficiency, which is not practical.

Following the above, in order to completely photograph the surface of the wafer chuck, those with ordinary knowledge in the art can understand that the camera is usually arranged above the wafer chuck. However, the vertical space inside the semiconductor machine is very compact and narrow, especially other functional modules are often set directly above the wafer chuck, so it is not easy to free up space for the camera. In addition, if the camera is to obliquely shoot the surface of the wafer chuck from the side, it will be impossible to see the whole surface of the wafer chuck due to the focal length and depth of field. Accordingly, the industry needs a new wafer chuck inspection system, which not only can be integrated in the limited space of the semiconductor machine, but also can use a camera to inspect the wafer chuck.

The present invention provides a wafer chuck detection system, which can be installed in a semiconductor machine table, and can use a camera to detect the wafer chuck from a horizontal direction.

The present invention provides a wafer chuck detection system for detecting the wafer chuck. The wafer chuck is defined with a bearing surface, and the bearing surface includes a first detection area and a second detection area. The wafer chuck inspection system includes a first camera module and a second camera module. The first photographing module is arranged on the first side of the wafer chuck, and is used for photographing the second detection area. The second photographing module is disposed on the second side of the wafer chuck, and is used for photographing the first detection area. The wafer chuck defines a center line, the first side and the second side are respectively located on two sides of the center line, and the first detection area and the second detection area are respectively located on both sides of the center line.

In some embodiments, the first camera module can include a first lens, the first lens has a first shortest focusing distance, the second camera module can include a second lens, the second lens has a second shortest focusing distance, the first The shortest focus distance may be the same as the second shortest focus distance. Here, the first shortest focusing distance is not greater than the distance from the first lens to the center line. In addition, the distance from the first lens to the center line is the same as the distance from the second lens to the center line. In addition, the first lens and the second lens may be located on a reference surface, the reference surface is parallel to the bearing surface, and the distance between the reference surface and the bearing surface is smaller than the first threshold value.

In some embodiments, the bearing surface may further include a third detection area and a fourth detection area, the third detection area and the fourth detection area are between the first detection area and the second detection area, and the first detection area and the third detection area are The detection area is on the same side of the center line, and the second detection area and the fourth detection area are on the same side of the center line. Here, the first photographing module can be used to photograph the second detection area and the fourth detection area, and the second photographing module can be used to photograph the first detection area and the third detection area. In addition, the first photographing module may include a first lens and a third lens, the second photographing module may include a second lens and a fourth lens, the first lens is used for photographing the second detection area, and the second lens is used for photographing the first lens a detection area, the third lens is used for photographing the fourth detection area, and the fourth lens is used for photographing the third detection area. In addition, the first lens has a first shortest focusing distance, the third lens has a third shortest focusing distance, and the third shortest focusing distance may be smaller than the first shortest focusing distance. Alternatively, the pixels of the first lens may be larger than the pixels of the third lens. On the other hand, the first camera module may include a first light source, the second camera module may include a second light source, and the first light source and the second light source are used to illuminate the bearing surface.

To sum up, the wafer chuck inspection system provided by the present invention has two camera modules, which are respectively arranged on both sides of the wafer chuck, which not only does not occupy the vertical space above the wafer chuck, but also avoids the focal length of a single lens. Not enough to cover the entire wafer chuck problem.

The features, objects and functions of the present invention will be further disclosed below. However, the following descriptions are only examples of the present invention, and should not be used to limit the scope of the present invention, that is, any equivalent changes and modifications made according to the scope of the patent application of the present invention will still be the essence of the present invention, Without departing from the spirit and scope of the present invention, it should be regarded as a further embodiment of the present invention.

Please refer to FIG. 1 and FIG. 2 together. FIG. 1 is a schematic top view of a wafer chuck inspection system according to an embodiment of the present invention, and FIG. 2 is a schematic side view of a wafer chuck inspection system according to an embodiment of the present invention. . As shown in the figure, the wafer chuck inspection system 1 is used to inspect the wafer chuck 2 , the wafer chuck inspection system 1 includes a first camera module 10 and a second camera module 12 , and the wafer chuck 2 defines a bearing surface 20 , the carrying surface 20 can be used to carry the wafer. Here, for example, the wafer chuck 2 may be disposed in one semiconductor machine, and the present embodiment does not limit the type of the semiconductor machine. In addition, this embodiment does not limit the size of the wafer that the wafer chuck 2 is used to carry, nor does it limit the size of the bearing surface 20 of the wafer chuck 2 . In practice, a center line 22 may be defined on the bearing surface 20 , and the center line 22 may divide the bearing surface 20 into a first detection area 200 and a second detection area 202 . Taking the example of FIG. 1 , the first detection area 200 may be the bearing surface 20 on the left side of the center line 22 , and the second detection area 202 may be the bearing surface 20 on the right side of the center line 22 . For convenience of description, in this embodiment, the left side of the center line 22 is defined as the first side of the wafer chuck 2 , and the right side of the center line 22 is defined as the second side of the wafer chuck 2 . That is, the first detection area 200 and the first side are on the same side of the centerline 22 , and the second detection area 202 and the second side are on the same side of the centerline 22 . The components of the wafer chuck inspection system 1 will be described below.

The first camera module 10 is disposed on the first side of the wafer chuck 2. The first camera module 10 may have a first lens 100 and a first light source 102. The first lens 100 is used for photographing the second detection area 202, and the first The light source 102 can be used to illuminate the carrier surface 20 . As can be seen from the figure, although the first lens 100 is located on the first side of the wafer chuck 2 , it is not used to photograph the first detection area 200 that is relatively close, but to photograph the second detection area 202 that is farther away. In one example, the first lens 100 has a first shortest focusing distance, and the first shortest focusing distance may be the distance from the first lens 100 to the center line 22 , that is, the distance D1 shown in FIG. 2 . Of course, the first shortest focusing distance of the first lens 100 may also be smaller than the distance D1, that is, at least the entire second detection area 202 should be covered. Those with ordinary knowledge in the art can understand that a lens has a corresponding shortest focusing distance. If the object to be photographed is closer to the shortest focusing distance, the lens may not be able to focus, and the photographed object will be blurred. Accordingly, in order to ensure that the first lens 100 can clearly photograph the bearing surface 20 , in this embodiment, the first lens 100 is only used to photograph the second detection area 202 that is far away, and the second detection area 202 is closest to the first lens 100 The edge should also be farther than the first shortest focusing distance of the first lens 100 . In addition, the depth of field of the first lens 100 should at least extend to the second side of the wafer chuck 2 , that is to say, the first lens 100 has at least a depth of field of distance D4 .

The second camera module 12 is disposed on the second side of the wafer chuck 2 . The second camera module 12 can also have a second lens 120 and a second light source 122 . The second lens 120 is used for photographing the first detection area 200 , and The second light source 122 can also be used to illuminate the support surface 20 . In one example, the second lens 120 also has a second shortest focusing distance, and the second shortest focusing distance may be the distance from the second lens 120 to the center line 22 , that is, the distance D2 shown in FIG. 2 . Of course, the second shortest focusing distance of the second lens 120 may also be smaller than the distance D2, that is, at least the entire first detection area 200 should be covered. Similarly, in order to ensure that the second lens 120 can clearly photograph the bearing surface 20 , in this embodiment, the second lens 120 is set only to photograph the first detection area 200 that is far away, and the first detection area 200 is closest to the second lens 120 The edge should also be farther than the second shortest focusing distance of the second lens 120 . In addition, the depth of field of the second lens 120 should at least extend to the first side of the wafer chuck 2 , that is to say, the second lens 120 has at least a depth of field of distance D3. In practice, the specifications of the first lens 100 may be the same as the specifications of the second lens 120 , for example, the first shortest focusing distance may be the same as the second shortest focusing distance. In addition, the first camera module 10 and the second camera module 12 can be arranged in symmetrical positions, that is, the distance from the first lens 100 to the center line 22 is the same as the distance from the second lens 120 to the center line 22 .

In addition, the first lens 100 and the second lens 120 are located on the same reference surface ref, the reference surface ref is parallel to the bearing surface 20, and the distance H between the reference surface ref and the bearing surface 20 is smaller than the first threshold value. In practice, the distance H is related to the semiconductor machine. If there is ample vertical space inside the semiconductor machine, the distance H can be larger. Conversely, if the vertical space inside the semiconductor machine is insufficient, the distance H will be smaller. In one example, the first threshold value may be 170 mm, and preferably, the distance H may be between 50 mm and 200 mm. It can be seen from the above that, different from the detection method in which a single lens is used to shoot the wafer chuck, in this embodiment, one bearing surface 20 is allocated to two lenses for shooting. , more consistent resolution. On the other hand, since each lens in this embodiment only needs to shoot part of the bearing surface 20 , the problem that the depth of field of a single lens is not enough to cover the entire bearing surface 20 is solved, and the partially blurred bearing surface 20 can also be avoided. In addition, since the lens of the wafer chuck inspection system 1 of the present embodiment is disposed on the side of the wafer chuck 2, the wafer chuck inspection system 1 can complete inspection when the vertical space of the semiconductor machine is limited.

In an example, the first lens 100 and the first light source 102 in the first camera module 10 are not necessarily on the same reference surface ref, as long as the first light source 102 can illuminate the bearing surface 20 of the wafer chuck 2, this embodiment The light source type of the first light source 102 is not limited. Similarly, the second lens 120 and the second light source 122 in the second photographing module 12 are not necessarily on the same reference surface ref, and this embodiment does not limit the light source type of the second light source 122 . In addition, the first light source 102 and the second light source 122 may each have a group (multiple) of lighting units, which can project uniformly diffused light. In addition, each lighting unit may be independently driven, and the user can selectively turn on or off different numbers of lighting units in the first light source 102 and the second light source 122 according to the size of the bearing surface 20 or the characteristics of the bearing surface 20 . Taking the example shown in FIG. 1 , for example, the first light source 102 may include, but is not limited to, four lighting units, and the plurality of lighting units may be scattered around the first lens 100 . On the other hand, in order to make the light irradiating the bearing surface 20 more uniform, the first light source 102 and the second light source 122 should be arranged at symmetrical positions of the wafer chuck 2 and illuminate the bearing surface 20 at the same angle. In practice, the first light source 102 and the second light source 122 may each be responsible for illuminating a part of the bearing surface 20. For example, the first light source 102 may be responsible for illuminating the first detection area 200 that is closer, and the second light source 122 may be responsible for illuminating the closer inspection area 200. The second detection area 202 is not limited in this embodiment.

It is worth mentioning that traditionally, when a single light source is used to illuminate the bearing surface, it is easy to have abnormal bright or dark bands on the image of the bearing surface, because the special cutting fine lines on the bearing surface cause stray light. In contrast, since the present embodiment illuminates different areas of the bearing surface 20 in sections, and the light sources (more than two) are more dispersed, the influence of stray light can be effectively reduced. In this way, the present embodiment can avoid abnormal bright bands or dark bands in the image, that is, the signal-to-noise ratio of foreign objects or defects in the image of the bearing surface 20 is improved. In practice, when the wafer chuck inspection system 1 detects foreign objects or defects in the image of the carrier surface 20, the first light source 102 and the second light source 122 will set a plurality of brightnesses, so that the first lens 100 and the second lens 120 can be respectively Images of the first detection area 200 and the second detection area 202 under different brightness are captured. Next, the processing unit (not shown) in the wafer chuck inspection system 1 will then analyze whether the images of the first inspection area 200 and the second inspection area 202 have abnormal features larger than a certain area. After obtaining the position of the abnormal feature, the processing unit can draw a distribution map of foreign objects or defects on the bearing surface 20 .

In addition, with the advancement of semiconductor technology, the size of the wafer chuck 2 may become larger and larger. The depth of field of the first lens 100 may not extend to the second side of the wafer chuck 2 , and the depth of field of the second lens 120 may not extend to the first side of the wafer chuck 2 . Alternatively, the images captured by the first lens 100 and the second lens 120 may have a problem of insufficient resolution. At this time, the photographing module of this embodiment can be improved, so that the photographing module is provided with more than one lens corresponding to different areas on the photographing bearing surface 20 to solve the above problem. Please refer to FIGS. 1 , 3 and 4 together. FIG. 3 is a schematic top view of a wafer chuck inspection system according to another embodiment of the present invention, and FIG. 4 is a schematic diagram of a wafer chuck inspection system according to another embodiment of the present invention. Schematic side view of the system. 3 and the embodiment shown in FIG. 1 are similar in that the wafer chuck inspection system 3 also includes a first camera module 30 and a second camera module 32 , and the wafer chuck 2 defines a bearing surface 20 for carrying Side 20 may be used to carry wafers. The difference between the embodiments in FIG. 3 and FIG. 1 is that in addition to a center line 22 defined on the carrying surface 20 , an auxiliary line 24 a may be defined between the center line 22 and the first side of the wafer chuck 2 . An auxiliary line 24b may also be defined between the line 22 and the second side of the wafer chuck 2 . Thereby, the bearing surface 20 can be divided into the first detection area 200 , the second detection area 202 , the third detection area 204 and the fourth detection area 206 by the center line 22 , the auxiliary line 24 a and the auxiliary line 24 b .

As shown in the figure, the left side of the auxiliary line 24a is the first detection area 200, the area between the auxiliary line 24a and the center line 22 is the third detection area 204, and the area between the center line 22 and the auxiliary line 24b is the fourth detection area 206. The right side of the line 24b is the second detection area 202 . In other words, the third detection area 204 and the fourth detection area 206 are between the first detection area 200 and the second detection area 202 , on the bearing surface 20 , from left to right are the first detection area 200 and the third detection area 200 , respectively. A detection area 204 , a fourth detection area 206 and a second detection area 202 .

In addition, the first camera module 30 of the wafer chuck inspection system 3 has a first lens 300, a third lens 302 and a first light source 304. The first lens 300 is used to photograph the second detection area 202 with the farthest The lens 302 is used to photograph the fourth detection area 206 with a relatively short distance, and the first light source 304 is used to illuminate the bearing surface 20 . As mentioned above, due to the large size of the wafer chuck 2 in this embodiment, the first lens 300 may not be enough to photograph half of the bearing surface 20 , so the first lens 300 is only used to photograph the distant second detection area 202 , and the second detection area 202 is closest to the edge of the first lens 300 , and should also be farther than the first shortest focusing distance of the first lens 300 . In other words, the first shortest focusing distance of the first lens 300 may be the distance D1 plus the distance D5. Likewise, the third shortest focusing distance of the third lens 302 may be the distance D1. In addition, as described in the previous embodiment, the first lens 300 has a depth of field at least a distance D6, and the third lens 302 has a depth of field at least a distance D5.

The second camera module 32 of the wafer chuck inspection system 3 has a second lens 320, a fourth lens 322 and a second light source 324. The second lens 320 is used to photograph the first inspection area 200 with the farthest distance, and the fourth lens 322 The second light source 324 is used to illuminate the bearing surface 20 for photographing the third detection area 204 with a relatively short distance. Similar to the first photography module 30 , the second lens 320 is only used to photograph the first detection area 200 that is far away, and the first detection area 200 is closest to the edge of the second lens 320 and should be farther than the second lens 320 The second shortest focusing distance. In other words, the second shortest focusing distance of the second lens 320 may be the distance D2 plus the distance D4. Likewise, the fourth shortest focusing distance of the fourth lens 322 may be the distance D2. In addition, the second lens 320 has a depth of field at least a distance D3, and the fourth lens 322 has a depth of field at least a distance D4. In practice, the specifications of the first lens 300 may be the same as the specifications of the second lens 320 , for example, the first shortest focusing distance may be the same as the second shortest focusing distance. Moreover, the specifications of the third lens 302 may be the same as the specifications of the fourth lens 322 , for example, the third shortest focusing distance may be the same as the fourth shortest focusing distance. In addition, the first photographing module 30 and the second photographing module 32 may be arranged at symmetrical positions, and the first lens 300 and the second lens 320 may be arranged on the same reference surface ref.

In one example, the specifications of the first lens 300 are different from the specifications of the third lens 302 . Assuming that the pixels corresponding to the first lens 300 and the third lens 302 are the same, the focal lengths of the first lens 300 and the third lens 302 may be different. For example, the first lens 300 may be a telephoto lens for photographing the distant first detection area 200 , and the third lens 302 may be a short-focus lens for photographing the relatively close third detection area 204 . In addition, assuming that the focal lengths of the first lens 300 and the third lens 302 are the same, the first lens 300 should correspond to a larger area of photosensitive elements, or the first lens 300 should have more pixels than the third lens 302 . Those with ordinary knowledge in the art can freely choose the focal lengths and pixels corresponding to the first lens 300 and the third lens 302, as long as the images captured by the first lens 300 and the third lens 302 should have similar resolutions and magnifications, All should belong to the category of the first lens 300 and the third lens 302 in this embodiment. In practice, the images captured by the first lens 300 and the third lens 302 have similar resolutions and magnifications, which can avoid discontinuous edges when the processing units in the wafer chuck inspection system 3 combine images.

It is worth mentioning that the horizontal heights of the third lens 302 and the fourth lens 322 should be the same and symmetrical, but are not limited to be set on the same reference surface ref. For convenience of description, in this embodiment, the first lens 300 , the second lens 320 , the third lens 302 , and the fourth lens 322 have the same horizontal height and are all set on the reference plane ref as an example. Similar to the previous embodiment, the distance H between the reference surface ref and the bearing surface 20 may be smaller than the first threshold value, and the distance H may be between 50 mm and 200 mm, which is not limited in this embodiment. As described in the previous embodiment, in this embodiment, one bearing surface 20 is allocated to four lenses for shooting. Since the area of the area each lens is responsible for shooting is further reduced, compared with the example in FIG. 1 , the one shown in FIG. 3 Examples should have higher, more consistent resolution. In addition, since each lens in this embodiment also only needs to shoot part of the bearing surface 20 , the problem that the depth of field of a single lens is insufficient to cover the entire bearing surface 20 can also be avoided, and the partially blurred bearing surface 20 can also be avoided. In addition, since the lens of the wafer chuck inspection system 3 of this embodiment is also arranged on the side of the wafer chuck 2, the wafer chuck inspection system 3 can also complete the inspection when the vertical space of the semiconductor machine is limited.

In one example, although the first light source 304 and the second light source 324 may each be responsible for illuminating a part of the bearing surface 20, the illumination areas of the first light source 304 and the second light source 324 may be different from those of the first lens 300 and the second lens. 320 , the shooting areas corresponding to the third lens 302 and the fourth lens 322 . Taking the first light source 304 as an example, a part of the lighting units in the first light source 304 may be responsible for illuminating the first detection area 200 that is relatively close, and another part of the lighting units in the first light source 304 may be responsible for illuminating the third detection area 204 that is farther away . Alternatively, each lighting unit of the first light source 304 may also cover and illuminate the first detection area 200 and the third detection area 204 at the same time, which is not limited in this embodiment.

To sum up, the wafer chuck inspection system provided by the present invention has two camera modules, which are respectively arranged on both sides of the wafer chuck, which not only does not occupy the vertical space above the wafer chuck, but also avoids the focal length of a single lens. Not enough to cover the entire wafer chuck problem.

1: Wafer chuck inspection system 10: The first photography module 100: First Shot 102: The first light source 12: The second photography module 120: Second shot 122: Second light source 2: Wafer chuck 20: Bearing surface 200: The first detection area 202: Second detection area 204: The third detection area 206: Fourth detection area 22: Centerline 24a: Auxiliary line 24b: Auxiliary line 3: Wafer chuck inspection system 30: The first photography module 300: First Shot 302: Third Shot 304: The first light source 32: Second photography module 320: Second Shot 322: Fourth Shot 324: Second Light Source D1~D6: Distance H: distance ref: reference surface

FIG. 1 is a schematic top view of a wafer chuck inspection system according to an embodiment of the present invention.

FIG. 2 is a schematic side view of a wafer chuck inspection system according to an embodiment of the present invention.

FIG. 3 is a schematic top view of a wafer chuck inspection system according to another embodiment of the present invention.

FIG. 4 is a schematic side view of a wafer chuck inspection system according to another embodiment of the present invention.

none

1: Wafer chuck inspection system

10: The first photography module

100: First Shot

102: The first light source

12: The second photography module

120: Second shot

122: Second light source

2: Wafer chuck

20: Bearing surface

200: The first detection area

202: Second detection area

22: Centerline

Claims (11)

A wafer chuck detection system is used for detecting a wafer chuck, the wafer chuck defines a bearing surface, the bearing surface includes a first detection area and a second detection area, and the wafer chuck detection system includes: a first photographing module disposed on a first side of the wafer chuck for photographing the second detection area; and a second photographing module, disposed on a second side of the wafer chuck, for photographing the first detection area; The wafer chuck defines a centerline, the first side and the second side are respectively located on two sides of the centerline, and the first detection area and the second detection area are located on both sides of the centerline respectively. The wafer chuck inspection system of claim 1, wherein the first camera module includes a first lens, the first lens has a first shortest focusing distance, the second camera module includes a second lens, The second lens has a second shortest focusing distance, and the first shortest focusing distance is the same as the second shortest focusing distance. The wafer chuck inspection system according to claim 2, wherein the first shortest focusing distance is not greater than the distance from the first lens to the center line. The wafer chuck inspection system according to claim 2, wherein the distance from the first lens to the center line is the same as the distance from the second lens to the center line. The wafer chuck inspection system of claim 2, wherein the first lens and the second lens are located on a reference plane, the reference plane is parallel to the bearing surface, and the distance between the reference plane and the bearing surface is smaller than a first a threshold value. The wafer chuck inspection system of claim 1, wherein the bearing surface further includes a third inspection area and a fourth inspection area, and the third inspection area and the fourth inspection area are in the first inspection area and the fourth inspection area. Between the second detection areas, the first detection area and the third detection area are on the same side of the center line, and the second detection area and the fourth detection area are on the same side of the center line. The wafer chuck inspection system according to claim 6, wherein the first camera module is used for photographing the second inspection area and the fourth inspection area, and the second camera module is used for photographing the first inspection area and the third detection area. The wafer chuck inspection system of claim 7, wherein the first camera module includes a first lens and a third lens, the second camera module includes a second lens and a fourth lens, and the first camera A lens is used to photograph the second detection area, the second lens is used to photograph the first detection area, the third lens is used to photograph the fourth detection area, and the fourth lens is used to photograph the third detection area. The wafer chuck inspection system of claim 8, wherein the first lens has a first shortest focusing distance, the third lens has a third shortest focusing distance, and the third shortest focusing distance is smaller than the first shortest focusing distance Focus distance. The wafer chuck inspection system of claim 8, wherein the pixels of the first lens are larger than the pixels of the third lens. The wafer chuck inspection system of claim 1, wherein the first camera module includes a first light source, the second camera module includes a second light source, and the first light source and the second light source are used to illuminate Light up the bearing surface.

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