Wafer laser slotting light spot automatic detection method and system

Abstract

The invention discloses a wafer laser slotting light spot automatic detection method and system, and relates to the technical field of wafer processing. The automatic detection method comprises the following steps: respectively fixing a wafer and a light spot detection sheet on a main workbench and an auxiliary detection table; according to a preset detection opportunity, the auxiliary detection table is moved to the position below the laser camera; shooting and positioning the light spot detection sheet; dotting along the X axis at a set interval, and meanwhile, controlling the height of the Z axis to be continuously adjusted to form a light spot dot matrix; shooting a light spot dot matrix image, analyzing the size and shape of the light spot, and screening the light spot meeting the preset size and shape; according to the X-axis position of the light spot meeting the condition, the corresponding Z-axis height is obtained to calculate the laser focal length, and compensation is carried out based on the calculated focal length; s7, after compensation, the main workbench and the auxiliary detection table are reset, and grooving continues; and repeating the steps until the grooving of the wafer is completed. According to the invention, light spot automatic detection and focal length compensation can be realized, the calibration is fast, and the consistency is good.

Description

Technical Field

[0001] The present invention relates to the field of wafer processing technology, and in particular to a method and system for automatically detecting a laser slotting spot on a wafer. Background Art

[0002] In the semiconductor device manufacturing process, chips are distributed in a grid pattern on the wafer. The wafer laser grooving process uses laser high-temperature vaporization along specific cutting lines to remove the circuit layer on the surface of the cutting line, thereby preventing cracking and pulling of the circuit layer in subsequent processes.

[0003] When laser grooving a wafer, the chip is fixed to the worktable, the cut line is positioned (aligned), and the laser is then directed onto the chip's cut line surface, vaporizing the circuit layer on the cut line, completing the grooving. The laser's focal length can fluctuate due to factors such as fluctuations in the optical path lenses and the platen height. Excessive fluctuations can cause the laser to become out of focus, resulting in insufficient energy density at the processing point, making it unable to fully vaporize the surface circuit layer. The laser can even radiate energy to surrounding areas, causing severe thermal effects. Therefore, regular laser focal length calibration is necessary after a period of operation.

[0004] In the existing technology, it is usually necessary to first clear the sheet in the slotting equipment, then place the sample for inspection on the workbench, and then, through specific parameter settings, continuously change the Z axis during the laser process to obtain a spot array. Then, manually judge the spot state and determine the Z axis position corresponding to the focus to achieve focal length calibration. This technology has two drawbacks. First, since there is only one worktable, after the wafer is placed, the spot inspection sheet cannot be placed, so the sheet in the equipment needs to be cleared first, which seriously affects the equipment utilization rate. Second, all operations need to be performed manually, which requires certain operating skills and self-awareness of the personnel, and cannot prevent mistakes. In addition, the calibration results vary due to the subjective judgment of different personnel, and the consistency is poor. Summary of the Invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a method and system for automatic detection of wafer laser slotting light spots, which can realize automatic detection of light spots and focal length compensation, and has fast calibration and good consistency.

[0006] The present invention provides the following technical solutions:

[0007] The present invention provides a method for automatically detecting a laser slotted spot on a wafer, which comprises the following steps:

[0008] S1. Fix the wafer and the spot detection piece on the main working table and the auxiliary detection table respectively;

[0009] S2. According to the preset detection timing, the auxiliary detection platform is moved to the bottom of the laser camera through the driving device;

[0010] S3, photographing and positioning the light spot detection piece through a laser camera;

[0011] S4, the driving device makes the laser dot along the X axis at a set interval, while controlling the Z axis height to continuously adjust to form a light spot array;

[0012] S5. Capture the light spot array image through a laser camera, analyze the size and shape of the light spots, and select the light spots that meet the preset size and shape;

[0013] S6. Obtain the corresponding Z-axis height according to the X-axis position of the light spot that meets the conditions to calculate the laser focal length, and perform compensation based on the calculated focal length;

[0014] S7. After compensation, the main working table and the auxiliary inspection table are reset through the driving device to continue grooving;

[0015] S8. Repeat steps S2 to S7 until the wafer grooving is completed.

[0016] Preferably, the preset detection timing includes at least one of before the start of slotting, at intervals of a specified number of rows, at intervals of a specified number of meters, and at intervals of a specified time.

[0017] Furthermore, the auxiliary inspection platform is fixed to one side of the main workbench and moves synchronously with the main workbench.

[0018] Preferably, in step S5, the preset shape is selected from at least one of a circle or a polygon.

[0019] Preferably, the preset shape is a circle, and the preset size is a preset diameter of the circular light spot.

[0020] Preferably, the preset shape is a rectangle, and the preset size is a preset length and width of the rectangular light spot.

[0021] Preferably, in step S5, the preset size is the minimum size of the light spot, that is, the size of the smallest light spot in the light spot array.

[0022] Preferably, the focal length compensation is performed by modifying the Z-axis height to a calculated value.

[0023] Furthermore, in the step S6, a verification step is also included after compensation is performed: the light spot is regenerated after compensation to confirm that the size and shape of the light spot meet the preset conditions. If the verification fails, an alarm is triggered and the grooving process is suspended, and steps S2 to S6 are repeated until the verification passes.

[0024] On the other hand, the present invention further provides a wafer laser slotting spot automatic detection system, which uses the above-mentioned wafer laser slotting spot automatic detection method to perform spot detection, and includes:

[0025] Main workbench, used to hold and move wafers;

[0026] Auxiliary detection table, fixed on one side of the main workbench, used to fix the spot detection piece;

[0027] A laser, used to emit laser light and form a light spot array;

[0028] A laser camera is provided on the laser and is used to capture the light spot image;

[0029] A driving assembly for driving the movement of the laser and / or the main working table;

[0030] The controller is electrically connected to the laser, laser camera and driving component, and is configured to execute the steps of the above method and output a focal length compensation instruction to the laser or driving component.

[0031] Furthermore, the main working table and the auxiliary inspection table are provided with a vacuum adsorption system to fix the wafer and the light spot inspection piece by vacuum adsorption.

[0032] The present invention has the following technical effects:

[0033] The detection method of the present invention is simple and reliable. When spot detection is required, there is no need to manually return the material and place a spot detection sheet. The auxiliary detection table can be directly translated to the bottom of the light outlet of the laser through the driving component, and then the focal length detection and calibration are automatically performed. After the calibration is completed, the main workbench and the auxiliary detection table are reset, and the grooving is continued. The detection method has a high degree of automation and can greatly improve the detection efficiency and the quality of wafer laser grooving. In addition, by arranging the auxiliary detection table on one side of the main workbench, there is no need to stop the machine or manually change materials, which can significantly improve the equipment utilization and consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 This is a laser dotting diagram provided in Example 1 of the present invention.

[0036] Figure 2 This is the light spot array pattern provided in Example 1 of the present invention.

[0037] Figure 3 This is a schematic structural diagram of the main workbench and auxiliary inspection platform provided in Example 1 of the present invention.

[0038] Figure 4 This is the light spot array pattern provided in Example 2 of the present invention.

[0039] Figure 5 This is the light spot array pattern provided in Example 3 of the present invention.

[0040] Explanation of the symbols in the figure: 1-laser; 2-light spot detection plate; 3-light spot; 4-wafer; 5-main workbench; 6-auxiliary detection table. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0042] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0043] In order to more fully understand the technical content of the present invention, the technical solution of the present invention is further introduced and illustrated in conjunction with specific embodiments below.

[0044] Example 1

[0045] A method for automatically detecting a laser slotted spot on a wafer comprises the following steps:

[0046] S1. Fix the wafer and the spot detection piece on the main working table and the auxiliary detection table respectively;

[0047] S2. The preset detection time is "detection every 1 hour". When the detection time is triggered, the auxiliary detection platform is moved horizontally to the bottom of the laser camera through the driving device;

[0048] S3, photographing and positioning the light spot detection piece through a laser camera;

[0049] S4, such as Figure 1 As shown, the laser 1 is driven by a driving device to mark the spots on the spot detection sheet 2 at a pitch of 25 μm along the X axis, and the Z axis height is controlled to be continuously adjusted at a pitch of 10 μm to form a spot array as shown in FIG. Figure 2 As shown;

[0050] S5. Capture the spot array image with a laser camera, analyze the size and shape of the spot 3, and select the spot 3 that meets the preset size and shape. In this embodiment, the preset shape is a circle, and the preset size is a diameter of 9 μm.

[0051] S6. Obtain the corresponding Z-axis height according to the X-axis position of the light spot 3 that meets the conditions, so as to calculate the laser focal length, and adjust the Z-axis height based on the calculated focal length;

[0052] S7. After compensation, the main working table and the auxiliary inspection table are reset through the driving device to continue grooving;

[0053] S8. Repeat steps S2 to S7 until the wafer grooving is completed.

[0054] This embodiment also provides a wafer laser slotting spot automatic detection system, which includes:

[0055] Main workbench 5, used for fixing and moving wafers;

[0056] The auxiliary detection table 6 is fixed on one side of the main workbench and is used to fix the light spot detection piece 2. Figure 3 As shown;

[0057] Laser 1, used for emitting laser light and forming a light spot array;

[0058] A laser camera, provided on the laser 1, for capturing a light spot image;

[0059] A drive assembly, including an X-axis drive, a Y-axis drive, and a Z-axis drive, for driving the movement of the laser 1 and the main workbench 5;

[0060] The controller is electrically connected to the laser 1, the laser camera and the driving component, and is configured to execute the steps of the above-mentioned detection method and output a focal length compensation instruction to the driving component.

[0061] Example 2

[0062] A method for automatically detecting a laser slotted spot on a wafer comprises the following steps:

[0063] S1. Fix the wafer and the spot detection piece on the main working table and the auxiliary detection table respectively;

[0064] S2. The detection timing is preset to "detect once every 10 rows". When the detection timing is triggered, the auxiliary detection platform is moved horizontally to the bottom of the laser camera through the driving device;

[0065] S3, photographing and positioning the light spot detection piece through a laser camera;

[0066] S4, through the driving device, the laser is used to mark the spot detection piece 2 along the X axis at a pitch of 20 μm to form a spot 3, and at the same time the Z axis height is controlled to be continuously adjusted at a pitch of 5 μm to form a spot array as shown in FIG. Figure 4 As shown;

[0067] S5. Capture an image of the light spot array using a laser camera, analyze the size and shape of the light spots, and select light spots that meet a preset size and shape. In this embodiment, the preset shape is a rectangle with a preset size of 30 μm in length and 8 μm in width.

[0068] S6. Obtain the corresponding Z-axis height according to the X-axis position of the light spot that meets the conditions to calculate the laser focal length, and adjust the Z-axis height based on the calculated focal length;

[0069] S7. After compensation, the main working table and the auxiliary inspection table are reset through the driving device to continue grooving;

[0070] S8. Repeat steps S2 to S7 until the wafer grooving is completed.

[0071] Example 3

[0072] A method for automatically detecting a laser slotted spot on a wafer comprises the following steps:

[0073] S1. Fix the wafer and the spot detection piece on the main working table and the auxiliary detection table respectively;

[0074] S2. The detection timing is preset to "detect once every 1m". When the detection timing is triggered, the auxiliary detection platform is moved horizontally to the bottom of the laser camera through the driving device;

[0075] S3, photographing and positioning the light spot detection piece through a laser camera;

[0076] S4, through the driving device, the laser is made to dot the spot detection piece 2 along the X axis at a pitch of 30 μm to form a spot 3, and at the same time the Z axis height is controlled to be continuously adjusted at a pitch of 15 μm to form a spot array as shown in FIG. Figure 5 As shown;

[0077] S5. Capture an image of the light spot array using a laser camera, analyze the size and shape of the light spots, and select light spots that meet a preset size and shape. In this embodiment, the preset shape is a square, and the preset size is a side length of 10 μm.

[0078] S6. Obtain the corresponding Z-axis height according to the X-axis position of the light spot that meets the conditions to calculate the laser focal length, and adjust the Z-axis height based on the calculated focal length;

[0079] S7, after compensation, regenerate the light spot and confirm that the size and shape of the light spot meet the preset conditions. If the verification fails, an alarm is triggered and the slotting process is suspended. Steps S2 to S7 are repeated until the verification passes.

[0080] S8. After passing the verification, the main working table and the auxiliary inspection table are reset through the driving device to continue grooving;

[0081] S9. Repeat steps S2 to S7 until the wafer slotting is completed.

[0082] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A method for automatically detecting laser slotting spots on wafers, characterized in that: The following steps are involved: S1. Fix the wafer and the spot detection piece on the main working table and the auxiliary detection table respectively; S2. According to the preset detection timing, the auxiliary detection platform is moved to the bottom of the laser camera through the driving device; S3, photographing and positioning the light spot detection piece through a laser camera; S4, the laser is driven by a driving device to mark dots along the X axis at a set interval, while the Z axis height is controlled to be continuously adjusted to form a light spot array; S5. Capture the light spot array image through a laser camera, analyze the size and shape of the light spots, and select the light spots that meet the preset size and shape; S6. Obtain the corresponding Z-axis height according to the X-axis position of the light spot that meets the conditions to calculate the laser focal length, and perform compensation based on the calculated focal length; S7. After compensation, the main working table and the auxiliary inspection table are reset through the driving device to continue grooving; S8. Repeat steps S2 to S7 until the wafer grooving is completed.

2. The method for automatically detecting a laser slotted spot on a wafer according to claim 1, wherein: The preset detection timing includes at least one of before the start of slotting, at intervals of a specified number of rows, at intervals of a specified number of meters, and at intervals of a specified time.

3. The automatic detection method for wafer laser slotting spots according to claim 1, wherein: The auxiliary detection table is fixed on one side of the main workbench and moves synchronously with the main workbench.

4. The method for automatically detecting a laser slotted spot on a wafer according to claim 1, wherein: In step S5, the preset shape is selected from at least one of a circle and a polygon.

5. The automatic detection method for wafer laser slotting spots according to claim 4, wherein: The preset shape is a circle, and the preset size is a preset diameter of the circular light spot.

6. The method for automatically detecting a laser slotted spot on a wafer according to claim 4, wherein: The preset shape is a rectangle, and the preset size is the preset length and width of the rectangular light spot.

7. The method for automatically detecting wafer laser slotting spots according to claim 1, wherein: In the step S5, the preset size is the size of the smallest spot in the spot array.

8. The method for automatically detecting wafer laser slotting spots according to claim 1, wherein: The focal length compensation method is to modify the Z-axis height to the calculated value.

9. The automatic detection method for wafer laser slotting spots according to claim 1, wherein: In the step S6, after the compensation is performed, a verification step is also included: the light spot is regenerated after the compensation to confirm that the size and shape of the light spot meet the preset conditions. If the verification fails, an alarm is triggered and the grooving process is suspended, and steps S2 to S6 are repeated until the verification passes.

10. A wafer laser slotting spot automatic detection system, which uses the wafer laser slotting spot automatic detection method according to any one of claims 1 to 9 to perform spot detection, characterized in that: It includes: Main workbench, used to hold and move wafers; Auxiliary detection table, fixed on one side of the main workbench, used to fix the spot detection piece; A laser, used to emit laser light and form a light spot array; A laser camera is provided on the laser and is used to capture the light spot image; A driving assembly for driving the movement of the laser and / or the main working table; The controller is electrically connected to the laser, laser camera and driving assembly.

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