Defect detection apparatus and defect detection method

Abstract

The invention relates to a defect detection apparatus and a defect detection method. In one aspect, the defect detection device comprises: a carrying table for supporting a wafer to be detected on the carrying table in a manner that the center of the wafer is suspended; the light source is arranged below the carrying table and is used for emitting light rays towards the back surface of the wafer, and the light source can move in the horizontal direction so as to scan the back surface; the detection device is arranged above the carrying table and is used for detecting defects of the wafer; the alignment device comprises an adsorption unit and an alignment unit, the adsorption unit is arranged below the carrying table and used for adsorbing the wafer, the adsorption unit can move in the vertical direction and can rotate to drive the adsorbed wafer to rotate around the central axis of the wafer, and the alignment unit is used for detecting the position of a notch of the wafer; and when the wafer is determined to be at the preset position based on the detection result, the adsorption unit is controlled to stop rotating. Therefore, the wafer position error caused by taking and placing the wafer after alignment can be reduced.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor manufacturing technologies, and in particular, to a defect detection device and a defect detection method. Background Art

[0002] In the production of wafers for manufacturing semiconductor devices, the surface quality of the wafers is crucial. Pinhole defects are a common type of wafer surface defect, usually manifested as tiny holes appearing on the surface of the wafer. Such defects can damage the insulation performance of the wafer, resulting in current leakage or short circuits, thereby affecting the performance and reliability of semiconductor devices.

[0003] For pinhole defects, currently, a transmissive optical detection method is usually adopted for detection. In this detection process, first, the wafer to be detected is taken out of the wafer cassette by a robotic arm and transferred to an alignment mechanism for alignment. For example, usually, the wafer is aligned according to the notch of the wafer so that its notch is in the desired orientation. Then, the wafer after alignment is taken out from the alignment mechanism by the robotic arm and transferred to the stage of the detection mechanism while keeping the orientation unchanged for defect detection. Thus, the coordinate positions of each defect can be accurately determined when detecting pinhole defects. Summary of the Invention

[0004] This part provides an overall summary of the present disclosure, rather than a full disclosure of the entire scope or all features of the present disclosure.

[0005] An object of the present disclosure is to provide a defect detection device capable of reducing the wafer position error caused by the picking and placing of the wafer after alignment.

[0006] To achieve the above object, according to one aspect of the present disclosure, a defect detection device is provided, which includes: A stage for supporting the wafer to be detected in a centrally suspended manner thereon; A light source disposed below the stage for emitting light towards the back surface of the wafer, and the light source can move in the horizontal direction to scan the back surface; A detection device disposed above the stage for detecting defects of the wafer; and An alignment device including an adsorption unit and an alignment unit. The adsorption unit is disposed below the stage for adsorbing the wafer, and the adsorption unit can move in the vertical direction and can rotate to drive the adsorbed wafer to rotate around its central axis. The alignment unit is used to detect the position of the notch of the wafer and control the adsorption unit to stop rotating when it is determined based on the detection result that the wafer is in a predetermined position.

[0007] In some embodiments, the light source and the adsorption unit can be respectively in a first position and a second position in a non-operating state. The first position is located outside the moving path of the adsorption unit in the vertical direction, and the second position is located below the moving path of the light source in the horizontal direction.

[0008] In some embodiments, the adsorption unit can include a vacuum chuck, a transmission shaft, and a motor. One end of the transmission shaft is connected to the bottom of the vacuum chuck, and the transmission shaft can be telescoped and rotated by the drive of the motor.

[0009] In some embodiments, the alignment unit can include a transmitting portion and a sensing portion respectively disposed on opposite sides of the stage. The transmitting portion is used to emit a laser beam towards the sensing portion, and the sensing portion is used to sense the laser beam to determine whether the wafer is in a predetermined position.

[0010] In some embodiments, the alignment unit can be disposed above the stage to capture the notch of the wafer, and determine whether the wafer is in a predetermined position based on the image of the captured notch and a reference image.

[0011] In some embodiments, the alignment unit can determine that the wafer is in a predetermined position when the similarity between the image of the captured notch and the reference image is greater than a threshold value.

[0012] In some embodiments, the detection device can include a scanning unit and a review camera. The scanning unit is used to collect the light passing through the wafer to form a defect coordinate map. The review camera takes pictures of the defects according to the coordinates of the defects in the defect coordinate map for review, and the review camera serves as the alignment unit.

[0013] In some embodiments, the stage can include an annular portion and at least three protruding portions. The protruding portions extend radially inwards from the inner side of the annular portion to support the edge of the wafer from below the wafer.

[0014] In some embodiments, the light source can be a linear light source with a length greater than or equal to the inner diameter of the annular portion.

[0015] According to another aspect of the present disclosure, a defect detection method is further provided, which is performed using the defect detection device according to any one of the above embodiments.

[0016] According to the above embodiments, by providing an adsorption unit below the stage for supporting the wafer to be detected, enabling the adsorption unit to adsorb the back surface of the wafer, move and rotate in the vertical direction, and by providing an alignment unit, enabling the alignment unit to control the adsorption unit to stop the rotated wafer at a predetermined position, the wafer placed on the stage can be aligned. Thereby, the wafer position error caused by picking and placing the wafer after alignment can be reduced, so that the error of the coordinate position of the detected defect can be reduced, and the accuracy of defect detection can be improved. In addition, since there is no need to move the wafer via a robotic arm to place it on the stage, the detection efficiency can also be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Through the following description with reference to the drawings, the features and advantages of the embodiments of the present disclosure will become more readily understood. The drawings are not drawn to scale, and some features may be enlarged or reduced to show details of specific parts. In the drawings: Figure 1 FIG. is a schematic structural view of a defect detection device according to an embodiment of the present disclosure, wherein the defect detection device is in a standby state.

[0018] Figure 2 is Figure 1 a top view of the defect detection device shown in

[0019] Figure 3 is a top view of the defect detection device shown in Figure 2 which holds the wafer to be detected.

[0020] Figure 4 Schematically shows the defect detection device in an alignment state.

[0021] Figure 5 Schematically shows the defect detection device in a detection state.

[0022] Figure 6 FIG. is a schematic structural view of an adsorption unit according to an embodiment of the present disclosure.

[0023] Figure 7 Schematically shows the working principle of an alignment unit according to an embodiment of the present disclosure.

[0024] In the drawings, the same or corresponding technical features, parts or components are denoted by the same or corresponding reference numerals. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The present disclosure will be described in detail below with reference to the drawings and by means of exemplary embodiments. It should be noted that the following detailed description of the present disclosure is for illustrative purposes only and is in no way a limitation of the present disclosure.

[0026] It should be noted that, for the sake of clarity, not all features of a specific embodiment are described and illustrated in the specification and the drawings. Moreover, to avoid obscuring the technical solutions of the present disclosure with unnecessary details, only the device structures and parts closely related to the technical solutions of the present disclosure are described and illustrated in the specification and the drawings, while other details that are not closely related to the technical content of the present disclosure and are known to those skilled in the art are omitted.

[0027] As mentioned before, during the detection process of pinhole defects, the wafer must first be moved to the alignment mechanism for alignment, and then moved to the detection mechanism for detection. That is to say, the wafer after alignment will also be grasped by the robotic arm and moved again.

[0028] The inventors noticed that the re-picking and placing of the wafer by the robotic arm after alignment may cause the orientation of the notch of the wafer to change, such that when the wafer is placed on the stage of the detection mechanism, the orientation of its notch is different from the orientation of the notch of the wafer after alignment. This will cause a large error in the coordinate position of the detected defect, thus having an adverse impact on the accuracy of defect detection.

[0029] In response to this, according to an embodiment of the present disclosure, a defect detection device is provided. Next, with reference to Figures 1 to 7 , the defect detection device 1 will be described in detail.

[0030] First, with reference to Figures 1 to 5 , the defect detection device 1 includes a stage 10, a light source 20, a detection device 30, and an alignment device 40.

[0031] The stage 10 is used to support the wafer W to be detected in a central suspended manner thereon. When the wafer W is supported on the stage 10, the front side of the wafer W faces upward and the back side faces downward. By suspending the center of the wafer W, it is possible to allow the light emitted by the light source 20 to irradiate the back side of the wafer W for detecting surface defects of the wafer. In the present disclosure, the front side of the wafer W refers to the side of the wafer W used to form circuit patterns in the manufacturing of semiconductor devices, and the back side of the wafer W is the side opposite to the front side.

[0032] The light source 20 is disposed below the stage 10 for emitting light S1 (as shown by the solid line with an arrow in Figure 4 ) toward the back side of the wafer W, and the light source 20 can move in the horizontal direction H1 to scan the back side.

[0033] The light source 20 can be, for example, an infrared light source to emit infrared light towards the back surface of the wafer W. The light ray S1 can pass through the wafer W from the back surface of the wafer W and be transmitted out from the front surface of the wafer W. When the light ray S1 passes through the wafer W, if there are defects on the front surface of the wafer W, the transmitted light ray S2 (as shown by the dotted line with an arrow in Figure 4 ), which is transmitted out from the front surface of the wafer W, will change compared to the light ray S1 emitted by the light source 20. Based on this, the detection of defects can be carried out.

[0034] The detection device 30 is arranged above the stage 10 for detecting defects of the wafer W.

[0035] The detection device 30 can be, for example, a high-resolution camera, a CCD sensor, an infrared sensor, etc. The detection device 30 can collect the transmitted light ray S2 transmitted out from the front surface of the wafer W, and can detect the defects on the front surface of the wafer W by analyzing the change of the transmitted light ray S2 compared to the light ray S1 emitted by the light source 20 (for example, the attenuation of light intensity, scattering, or the change of refraction angle, etc.).

[0036] The alignment device 40 includes an adsorption unit 401 and an alignment unit 402. The adsorption unit 401 is arranged below the stage 10 for adsorbing the wafer W, and the adsorption unit 401 can move in the vertical direction H2 and can rotate to drive the adsorbed wafer W to rotate around its central axis L ( Figure 4 shown as rotating counterclockwise in the figure, however, it can also rotate clockwise). The alignment unit 402 is used to detect the position of the notch V of the wafer W (see Figure 3 ), and controls the adsorption unit 401 to stop rotating when it is determined based on the detection result that the wafer W is in a predetermined position.

[0037] In this case, the adsorption unit 401 can contact the back surface of the wafer W supported on the stage 10 by moving upward in the vertical direction H2, and separate from the back surface of the wafer W by moving downward in the vertical direction H2. For example, when moving upward, the adsorption unit 401 can move to lift the wafer W from below the wafer W so that the wafer W is slightly separated from the stage 10. Moreover, the adsorption unit 401 can adsorb the back surface of the wafer W and drive the adsorbed wafer W to rotate around the central axis L of the wafer W by rotating, so that the wafer W moves to a predetermined position. The alignment unit 402 can detect the position of the notch V of the wafer W, and judge whether the wafer W is in a predetermined position based on the position of the notch V. Moreover, the alignment unit 402 can control the adsorption unit 401 to stop rotating when it is determined that the wafer W has rotated to a predetermined position, so that the wafer W adsorbed on the adsorption unit 401 stops at a predetermined position.

[0038] In this way, after alignment, the wafer W only needs to be slightly moved downward in the vertical direction H2 so as to be positioned on the stage 10, rather than being picked up and moved by the robotic arm and then placed on the stage 10. Thus, the wafer position error caused by the pick-and-place of the wafer W after alignment can be reduced, thereby reducing the error of the coordinate position of the detected defect, and further improving the accuracy of defect detection. In addition, since there is no need to move the wafer W by the robotic arm to place the wafer W in position on the stage 10, the detection efficiency can also be improved.

[0039] In some embodiments, such as Figure 1 and Figure 4 and Figure 5 as shown in, the light source 20 and the adsorption unit 401 can be respectively in the first position P1 and the second position P2 in the non-working state. The first position P1 is located outside the moving path of the adsorption unit 401 in the vertical direction H2, and the second position P2 is located below the moving path of the light source 20 in the horizontal direction H1.

[0040] In this way, during the alignment process, when the adsorption unit 401 moves upward in the vertical direction H2 to adsorb the back surface of the wafer W, since the light source 20 is not working and is in the first position P1 outside the moving path of the adsorption unit 401, the adsorption unit 401 will not interfere with the light source 20. During the detection process, when the light source 20 moves in the horizontal direction H1 to scan the back surface of the wafer W, since the adsorption unit 401 is not working and is below the moving path of the light source 20, the light source 20 will not interfere with the adsorption unit 401.

[0041] Thus, interference between the light source 20 and the adsorption unit 401 during the alignment process and the detection process can be avoided, thereby improving the working stability of the defect detection device 1.

[0042] In some embodiments, such as Figure 2 and Figure 3 as shown in, the stage 10 may include an annular portion 101 and at least three protruding portions 102. The protruding portions 102 extend radially inward from the inside of the annular portion 101 for supporting the edge of the wafer W from below the wafer W.

[0043] It should be noted that, for clarity, Figure 2 and Figure 3 the detection device 30 and the alignment unit 402 are omitted in.

[0044] By providing at least three protrusions 102, the wafer W can be stably supported on the stage 10. Moreover, since the entire edge of the wafer W is not supported, light rays S1 emitted by the light source 20 are allowed to irradiate the edge for defect detection. In addition, the annular portion 101 can restrict the movement range of the wafer W and prevent the wafer W from being damaged due to accidental detachment from the adsorption unit 401 during rotation.

[0045] It is conceivable that these protrusions 102 can be evenly arranged in the circumferential direction of the annular portion 101 and can be of relatively small size, so as to occupy as small an area as possible on the edge of the wafer W while ensuring the ability to support the wafer W, thereby reducing the impact on the detection of surface defects of the wafer.

[0046] In some embodiments, as Figure 2 and Figure 3 shown, the light source 20 can be a linear light source whose length is greater than or equal to the inner diameter of the annular portion 101 of the stage 10.

[0047] In this way, the light source 20 can scan the entire back surface of the wafer W by moving horizontally only once, avoiding the incomplete defect detection caused by missing some areas of the back surface scan, thereby improving the detection accuracy.

[0048] In some embodiments, referring to Figure 6 , the adsorption unit 401 can include a vacuum chuck 4011, a transmission shaft 4012, and a motor 4013. One end of the transmission shaft 4012 is connected to the bottom of the vacuum chuck 4011, and the transmission shaft 4012 can be driven by the motor 4013 to expand, contract, and rotate.

[0049] The vacuum chuck 4011 can adsorb the back surface of the wafer W. The transmission shaft 4012 can move in the vertical direction H2 by expansion and contraction, thereby driving the connected vacuum chuck 4011 to move in the vertical direction H2. Moreover, the transmission shaft 4012 can drive the vacuum chuck 4011 to rotate by rotation.

[0050] Exemplarily, in Figure 6 , the transmission shaft 4012 can include a driving screw 4012a and a driven rod 4012b. By rotating the driving screw 4012a, the driven rod 4012b can be driven to move in the vertical direction H2 to drive the vacuum chuck 4011 connected to the driven rod 4012b to move in the vertical direction H2. In addition, the driven rod 4012b can also be rotated by the drive of the motor 4013 to drive the vacuum chuck 4011 to rotate.

[0051] In some embodiments, referring to Figure 7, the alignment unit 402 may include a transmitting portion 4021 and a sensing portion 4022 respectively disposed on opposite sides of the stage 10. The transmitting portion 4021 is configured to emit a laser S3 toward the sensing portion 4022, and the sensing portion 4022 is configured to sense the laser S3 to determine whether the wafer W is in a predetermined position.

[0052] Specifically, the transmitting portion 4021 and the sensing portion 4022 are arranged to face each other in the vertical direction so that the laser S3 emitted by the transmitting portion 4021 in the vertical direction can be sensed by the sensing portion 4022, and the transmitting portion 4021 is positioned such that the emitted laser S3 passes through the notch V of the wafer W in the predetermined position.

[0053] In this way, during the alignment process, only when the wafer W rotates to the predetermined position, the laser S3 emitted by the transmitting portion 4021 is allowed to pass through the wafer W via the notch V and be sensed by the sensing portion 4022. At other positions, the laser S3 will be blocked by the edge of the wafer W, so that it cannot be sensed by the sensing portion 4022. Thus, it can be accurately detected whether the wafer W has reached the predetermined position.

[0054] In some embodiments, as Figure 4 shown, the alignment unit 402 may be disposed above the stage 10 to capture the notch V of the wafer W and determine whether the wafer W is in a predetermined position based on the image of the captured notch V and a reference image.

[0055] The reference image may be an image of the notch V of the wafer W when it is in the predetermined position. The reference image may be pre - saved in the form of a picture, for example. By capturing the image of the notch V of the rotating wafer W and comparing it with the reference image, it can be accurately determined whether the wafer W is in the predetermined position.

[0056] It can be conceived that the alignment unit 402 may determine that the wafer W is in the predetermined position when the similarity between the image of the captured notch V and the reference image is greater than a threshold value.

[0057] For example, the threshold value can be set to 0.9. In this way, when the similarity between the image of the captured notch V and the reference image is greater than 90%, it can be determined that the wafer W is in the predetermined position. Thus, the accuracy of the determination can be improved.

[0058] In some embodiments, the detection device 30 may include a scanning unit and a review camera. The scanning unit is configured to collect the transmitted light S2 passing through the wafer W to form a defect coordinate map, and the review camera takes pictures of the defects according to the coordinates of the defects in the defect coordinate map for review, and the review camera serves as the alignment unit 402.

[0059] The review camera can capture the morphological images of these defects according to the coordinates of these defects in the defect coordinate map, and classify these defects by means of manual inspection or image analysis on the morphological images to confirm whether the defects belong to pinhole defects, thereby improving the detection accuracy. In this embodiment, the review camera can be used as the alignment unit 402. That is to say, the review camera can be used to capture the notch V of the wafer W, and judge whether the wafer W is in the predetermined position according to the image of the captured notch V and the reference image.

[0060] In this way, there is no need to set up an additional imaging device, which not only saves costs, but also avoids the problem that the imaging device may interfere with the detection device 30 when an additional imaging device is set up.

[0061] According to another aspect of the present disclosure, a defect detection method is also provided. This defect detection method is performed using the defect detection device 1 of any of the above embodiments.

[0062] Next, in conjunction with Figures 1 to 5 the defect detection device 1 shown in, this defect detection method will be briefly described.

[0063] In the preparation state (as shown in Figure 1 ), the light source 20 is in the first position P1, and the adsorption unit 401 of the alignment device 40 is in the second position P2. The wafer W to be detected is taken out of the wafer cassette via the robotic arm and transferred onto the stage 10.

[0064] During the alignment process (as shown in Figure 4 ), the adsorption unit 401 moves upward in the vertical direction H2 to contact the back surface of the wafer W and slightly lift the wafer W from the stage 10. Then, the adsorption unit 401 adsorbs the back surface of the wafer W and rotates to drive the wafer W to rotate around its central axis L. At the same time, the alignment unit 402 detects the position of the notch V of the wafer W, and when the notch V reaches the predetermined position, controls the adsorption unit 401 to stop rotating, so that the wafer W adsorbed on the adsorption unit 401 stops at the predetermined position. Subsequently, the adsorption unit 401 releases the adsorption of the wafer W and moves downward in the vertical direction H2 to make the wafer W reposition on the stage 10, and the adsorption unit 401 then continues to move to the second position P2.

[0065] During the detection process (as shown in Figure 5As shown, the light source 20 emits light rays S1 towards the back surface of the wafer W and moves in the horizontal direction H1 to scan the back surface of the wafer W. At the same time, the detection device 30 collects the transmitted light rays S2 transmitted from the front surface of the wafer W and detects the defects on the front surface of the wafer W by analyzing the changes in the transmitted light rays S2 compared to the light rays S1. After the detection is completed, the light source 20 moves back along the horizontal direction H1 to return to the first position P1. Thus, the entire defect detection process is completed.

[0066] In the present disclosure, although the present disclosure has been described with reference to exemplary embodiments, it should be understood that the present disclosure is not limited to the specific embodiments described and illustrated in detail herein. Without departing from the scope defined by the claims of the present disclosure, those skilled in the art can make various changes to the exemplary embodiments.

[0067] The features mentioned and / or illustrated in the above description of the exemplary embodiments of the present disclosure can be combined in the same or similar manner into one or more other embodiments, combined with the features in other embodiments or replace the corresponding features in other embodiments. The technical solutions obtained by such combination or replacement should also be regarded as being included within the protection scope of the present disclosure.

Claims

1. A defect detection device, characterized in that, Comprising: A stage for supporting a wafer to be detected in a centrally suspended manner thereon; A light source disposed below the stage for emitting light toward the back surface of the wafer, and the light source being movable in a horizontal direction to scan the back surface; A detection device disposed above the stage for detecting defects of the wafer; And An alignment device including an adsorption unit and an alignment unit. The adsorption unit is disposed below the stage for adsorbing the wafer, and the adsorption unit is movable in a vertical direction and can rotate to drive the adsorbed wafer to rotate about its central axis. The alignment unit is used to detect the position of the notch of the wafer and control the adsorption unit to stop rotating when it is determined that the wafer is in a predetermined position based on the detection result.

2. The defect detection device according to claim 1, wherein The light source and the adsorption unit are respectively in a first position and a second position in a non-operating state. The first position is located outside the moving path of the adsorption unit in the vertical direction, and the second position is located below the moving path of the light source in the horizontal direction.

3. The defect detection device according to claim 1 or 2, characterized in that, The adsorption unit includes a vacuum chuck, a transmission shaft, and a motor. One end of the transmission shaft is connected to the bottom of the vacuum chuck, and the transmission shaft can be driven by the motor to expand, contract, and rotate.

4. The defect detection device according to claim 1 or 2, characterized in that, The alignment unit includes a transmitting portion and a sensing portion respectively disposed on opposite sides of the stage. The transmitting portion is used to emit laser light toward the sensing portion, and the sensing portion is used to sense the laser light to determine whether the wafer is in the predetermined position.

5. The defect detection device according to claim 1 or 2, characterized in that, The alignment unit is disposed above the stage for photographing the notch of the wafer and determining whether the wafer is in the predetermined position based on the image of the photographed notch and a reference image.

6. The defect detection device according to claim 5, characterized in that, The alignment unit determines that the wafer is in the predetermined position when the similarity between the image of the photographed notch and the reference image is greater than a threshold.

7. The defect detection device according to claim 5, characterized in that, The detection device includes a scanning unit and a review camera. The scanning unit is used to collect the light passing through the wafer to form a defect coordinate map. The review camera photographs the defects according to the coordinates of the defects in the defect coordinate map for review, and the review camera serves as the alignment unit.

8. The defect detection device according to claim 1 or 2, characterized in that, The stage includes an annular portion and at least three protruding portions. The protruding portions extend radially inward from the inside of the annular portion for supporting the edge of the wafer from below the wafer.

9. The defect detection device according to claim 8, wherein The light source is a linear light source having a length greater than or equal to the inner diameter of the annular portion.

10. A defect detection method, characterized in that, Performed using the defect detection device according to any one of claims 1 to 9.

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