Method for detecting foreign objects in processing tank

Abstract

This disclosure provides a method for detecting foreign objects in a processing tank, comprising the following steps: capturing an identification pattern disposed on the bottom of the processing tank or disposed on the optical lens using an optical lens to obtain a first image; placing a wafer in the processing tank; removing the wafer from the processing tank; capturing an image of the processing tank after the wafer has been removed using the optical lens to obtain a second image; and identifying the second image and the first image. If the second image is the same as the first image, the identification is considered successful and a first signal is output; if the second image is different from the first image, the identification is considered unsuccessful and a second signal is output.

Description

[Technical Field]

[0001] The present invention relates to a method for detecting foreign objects in a processing tank of a semiconductor process, and more particularly to a method for detecting foreign objects in a processing tank. [Previous Technology]

[0002] In semiconductor manufacturing, it is crucial to continuously monitor the state of the processing tank. This not only ensures product quality but also allows for immediate intervention in case of problems, minimizing potential losses. Generally, the monitoring device / system is mounted on a robotic arm because the wafer moves with the arm and can avoid the influence of highly corrosive liquids in the tank. However, this can affect the accuracy of detection. For example, when identifying the presence of foreign objects in the processing tank, optical lenses are typically used to detect the ratio of bright to dark areas to determine the presence of foreign objects. However, this method can lead to misjudgments due to factors such as the liquid in the tank, the reflection of foreign objects, and the angle of the foreign objects. [Summary of the Invention]

[0003] The present invention provides a method for detecting foreign objects in a processing tank, which uses an identification pattern on the bottom of the processing tank or on an optical lens to avoid misjudgment caused by interference from liquid in the processing tank, reflection of foreign objects, angle of foreign objects, etc.

[0004] One embodiment of the present invention provides a method for detecting foreign objects in a processing tank, comprising: taking a picture of an identification pattern disposed on the bottom of the processing tank or disposed on the optical lens to obtain a first image; placing a wafer in the processing tank; removing the wafer from the processing tank; taking a picture of the processing tank after the wafer has been removed from the processing tank using the optical lens to obtain a second image; and identifying the second image and the first image. If the second image is the same as the first image, the identification is considered successful and a first signal is output; if the second image is different from the first image, the identification is considered unsuccessful and a second signal is output.

[0005] In some embodiments, the first signal enables the process equipment to maintain the process and continue placing the next wafer in the processing tank, while the second signal enables the process equipment to issue a warning or stop the process.

[0006] In some embodiments, the pattern being identified includes a grid pattern.

[0007] In some embodiments, the foreign object includes a wafer fragment.

[0008] In some embodiments, the method for detecting foreign objects in the processing tank further includes: illuminating the processing tank by turning on a light source disposed around the processing tank before taking a picture of the processing tank after the wafer has been removed from the processing tank by an optical lens.

[0009] In some embodiments, the method for detecting foreign objects in the processing tank further includes: after being identified as qualified and outputting a first signal, the first signal can turn off the light source.

[0010] In some embodiments, the light source is positioned below the processing tank.

[0011] In some embodiments, the wafer is removed from the processing tank by a robotic arm, and the light source is disposed on the robotic arm.

[0012] In some embodiments, the optical lens is mounted on a robotic arm.

[0013] In some embodiments, the processing tank is filled with water that can completely immerse the wafer.

[0014] Based on the above, in the above method for detecting foreign objects in a processing tank, the identification pattern on the bottom of the processing tank or on the optical lens is used to avoid misjudgment caused by interference such as the liquid in the processing tank, the reflection of the foreign object, or the angle of the foreign object in identifying whether there is a foreign object in the processing tank.

Implementation Method

[0016] The invention is described more fully with reference to the drawings of this embodiment. However, the invention may be embodied in various different forms and should not be limited to the embodiments described herein. The thickness of layers and regions in the drawings is enlarged for clarity. The same or similar reference numerals denote the same or similar elements, which will not be repeated in the following paragraphs.

[0017] It should be understood that when an element is referred to as being "on" or "connected" to another element, it may be directly on or connected to the other element, or there may be an intermediate element. If an element is referred to as being "directly on" or "directly connected" to another element, there is no intermediate element. As used herein, "connection" may refer to a physical and / or electrical connection, and "electrical connection" or "coupling" may mean that there are other elements between two elements. "Electrical connection" as used herein may include physical connections (e.g., wired connections) and physical disconnections (e.g., wireless connections).

[0018] As used herein, “about,” “approximately,” or “substantially” includes the value mentioned and the average value within an acceptable range of deviations that can be determined by one of ordinary skill in the art, taking into account the measurement under discussion and the specific number of errors associated with the measurement (i.e., limitations of the measurement system). For example, “about” may mean within one or more standard deviations of the value, or within ±30%, ±20%, ±10%, ±5%. Furthermore, as used herein, “about,” “approximately,” or “substantially” may be chosen based on optical, etched, or other properties, and a single standard deviation may not be applied to all properties.

[0019] The terminology used herein is for illustrative purposes only and is not intended to limit the scope of this disclosure. In this context, the singular form includes the plural form unless the context otherwise requires.

[0020] Figures 1A and 1B are top and cross-sectional schematic diagrams of a method for detecting foreign objects in a processing tank according to an embodiment of the present invention. Figure 1C is a flowchart of a method for detecting foreign objects in a processing tank according to an embodiment of the present invention. Figure 2A is a top and cross-sectional schematic diagram of a method for detecting foreign objects in a processing tank according to another embodiment of the present invention. Figure 2B is a flowchart of a method for detecting foreign objects in a processing tank according to another embodiment of the present invention. Figure 3 is a cross-sectional schematic diagram of a method for detecting foreign objects in a processing tank according to yet another embodiment of the present invention. Figure 4 is a cross-sectional schematic diagram of a method for detecting foreign objects in a processing tank according to yet another embodiment of the present invention.

[0021] Referring to Figures 1A, 1B and 1C, a method for detecting foreign objects in a processing tank may include the following steps.

[0022] First, step S1 (i.e., recording the bottom pattern) as shown in FIG1C is performed. The identification pattern 110 disposed at the bottom of the processing tank 100 is photographed by the optical lens 10 to obtain a first image. In some embodiments, the identification pattern 110 may include a grid pattern.

[0023] Next, step S2 (i.e., wafer entering the water tank) as shown in FIG1C is performed. The wafer (not shown) is placed in the processing tank 100. In some embodiments, the processing tank 100 is filled with water that can completely immerse the wafer. In this embodiment, the processing tank 100 may be a water tank.

[0024] Then, step S3 (i.e., picking up the wafer with an arm at a specific position) as shown in FIG1C is performed. The wafer is removed from the processing tank 100 and placed at a specific position.

[0025] Then, step S4 (i.e., taking and transmitting a photograph) as shown in FIG1C is performed. The processing tank 100 after the wafer is taken out of the processing tank 100 is photographed through the optical lens 10 to obtain a second image.

[0026] Next, step S5 (i.e., identification) as shown in FIG1C is performed. The second image and the first image are identified. If the second image is the same as the first image, the identification is qualified (pass as shown in FIG1C) and a first signal is output. If the second image is different from the first image, the identification is failed (fail as shown in FIG1C) and a second signal is output. The identification pattern 110 can clearly identify the foreign object 1000 and avoid misjudgment caused by interference such as liquid in the processing tank 100, reflection of the foreign object, and angle of the foreign object. For example, even if a sheet-like foreign object 1000 (e.g., a wafer fragment) falls into the processing tank 100 in an oblique position, the present invention will not cause misjudgment due to the reflection of the foreign object 1000. This is because the above identification is based on the difference between the first image and the second image (e.g., the second image is the same as the first image in region R1, while the second image is different from the first image in region R2) rather than based on the ratio of bright and dark areas in the processing tank 100. In other words, the present invention effectively avoids interference such as the liquid in the processing tank 100, the reflection of the foreign object 1000, and the angle of the foreign object 1000 by setting the identification pattern 110 at the bottom of the processing tank 100.

[0027] In some embodiments, the first signal enables the process equipment to maintain the process and continue placing the next wafer into the processing tank 100, while the second signal enables the process equipment to issue a warning or stop the process (e.g., step S6). This allows for immediate intervention when a situation occurs (e.g., wafer fragments remain in the processing tank 100), reducing associated losses. For example, a subsequent wafer placed in the processing tank 100 may collide with a wafer fragment remaining in the processing tank 100, causing secondary damage. In some embodiments, the foreign object 1000 may include a wafer fragment.

[0028] Referring to Figures 2A and 2B, the method for detecting foreign objects in a processing tank may further include illuminating the processing tank 100 with a light source 12 disposed around it before photographing the processing tank 100 after the wafer has been removed from it using the optical lens 10 (e.g., step S31 shown in Figure 2B). This increases the clarity of the second image acquired in the subsequent step S4, thereby improving the accuracy of identifying the first and second images in step S5. Furthermore, as mentioned above, since the reflection of the foreign object 1000 does not interfere with the identification, the placement of the light source 12 can significantly improve the accuracy of identification. In some embodiments, the light source 12 may be disposed below or above the processing tank 100. In some embodiments, the wafer is removed from the processing tank 100 by a robotic arm (the arm mentioned in step S3 of Figure 2B), and the light source 12 may be disposed on the robotic arm. In some embodiments, the optical lens 10 may also be disposed on the robotic arm. In this embodiment, the specific position where the wafer is removed from the processing tank 100 and moved is the position where the second image is captured.

[0029] In some embodiments, after being identified as qualified (pass as shown in FIG2B) and the first signal is output, the first signal can turn off the light source 12 (e.g., step S32 as shown in FIG2B) and cause the process equipment to maintain the process program and continue to place the next wafer in the processing tank 100.

[0030] Referring to Figures 3 and 4, the identification pattern 210 can be set on the optical lens 20. In this way, during step S1 (i.e., recording the bottom pattern) as shown in Figure 1C, the identification pattern 210 set on the optical lens 20 can also be photographed by the optical lens 20 to obtain a first image.

[0031] In summary, in the method for detecting foreign objects in a processing tank in the above embodiments, the identification pattern on the bottom of the processing tank or on the optical lens is used to avoid misjudgment caused by interference such as the liquid in the processing tank, the reflection of the foreign object, or the angle of the foreign object in identifying whether there is a foreign object in the processing tank. [Simplified Explanation of the Diagram]

[0015] Figures 1A and 1B are top and cross-sectional schematic diagrams of a method for detecting foreign objects in a processing tank according to an embodiment of the present invention. Figure 1C is a flowchart of a method for detecting foreign objects in a processing tank according to an embodiment of the present invention. Figure 2A is a top and cross-sectional schematic diagram of a method for detecting foreign objects in a processing tank according to another embodiment of the present invention. Figure 2B is a flowchart of a method for detecting foreign objects in a processing tank according to another embodiment of the present invention. Figure 3 is a cross-sectional schematic diagram of a method for detecting foreign objects in a processing tank according to yet another embodiment of the present invention. Figure 4 is a cross-sectional schematic diagram of a method for detecting foreign objects in a processing tank according to yet another embodiment of the present invention.

Claims

1. A method for detecting foreign objects in a processing tank, comprising: A first image with a first bottom pattern is obtained by photographing an identification pattern disposed on the bottom of the processing tank or disposed on the optical lens using an optical lens, wherein the first bottom pattern includes an image of the bottom of the processing tank and an image of the identification pattern; after obtaining the first image, a wafer is placed in the processing tank; the wafer is removed from the processing tank; and the processing tank after the wafer is removed from the processing tank is photographed using the optical lens to obtain a second image with a second bottom pattern, wherein the second bottom pattern includes the image of the bottom of the processing tank and the image of the identification pattern, wherein: if the second image is the same as the first image, a first signal is obtained; and if the second image contains a foreign object pattern overlapping the identification pattern, making the second image different from the first image, a second signal is obtained.

2. The method for detecting foreign objects in a processing tank as described in claim 1, wherein the first signal enables the process equipment to maintain the process program and continue placing the next wafer in the processing tank, and the second signal enables the process equipment to issue a warning or stop the process program.

3. The method for detecting foreign objects in a processing tank as described in claim 1, wherein the identification pattern includes a grid pattern.

4. The method for detecting foreign matter in a processing tank as described in claim 1, wherein the foreign matter includes a wafer fragment.

5. The method for detecting foreign objects in a processing tank as described in claim 1, further comprising: Before photographing the processing tank after the wafer has been removed from the processing tank through the optical lens, a light source disposed around the processing tank is turned on to illuminate the processing tank.

6. The method for detecting foreign objects in a processing tank as described in claim 5, further comprising: After being identified as qualified and the first signal is output, the first signal can turn off the light source.

7. The method for detecting foreign objects in a processing tank as described in claim 5, wherein the light source is disposed below the processing tank.

8. The method for detecting foreign objects in a processing tank as described in claim 5, wherein the wafer is removed from the processing tank by a robotic arm, and the light source is disposed on the robotic arm.

9. The method for detecting foreign objects in a processing tank as described in claim 8, wherein the optical lens is disposed on the robotic arm.

10. The method for detecting foreign matter in a processing tank as described in claim 1, wherein the processing tank is filled with water capable of completely immersing the wafer therein.

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