A follow-up temperature rise compensation method for a wafer continuous processing system

Abstract

The present application relates to a kind of wafer continuous processing system's servo temperature rise compensation method, it includes the following steps, the surface of the wafer is scanned by range finder, the surface topography data of the wafer is obtained, and initial height compensation model is generated based on the surface topography data;Actual distance of the wafer surface in the range finding section to processing piece is collected to calculate the theoretical distance under the condition that the plane area coordinate does not occur thermal deformation;Actual average distance d_real and theoretical average distance d_ideal are differentially processed, and the thermal deformation difference value d_diff caused by temperature rise is obtained;Thermal deformation difference value d_diff is used as dynamic compensation parameter, and additional distance of the processing piece is moved in height direction d_diff is superimposed in height compensation model in real time, drives.The present application can realize high-precision dynamic closed-loop compensation of linear motion module thermal drift, avoid the structure design of space interference, error minimization of coaxial linkage, to significantly improve the focusing consistency and precision of laser processing.

Description

Technical Field

[0001] This invention relates to the technical field of semiconductor processing, and in particular to a method for compensating for temperature rise in a continuous wafer processing system. Background Technology

[0002] In the field of semiconductor or optical material manufacturing, laser processing is widely used for wafer modification or cutting to prepare modified layers. Given the inherent mechanical tolerances of the motion platform and the microscopic irregularities on the wafer surface, conventional techniques often employ a pre-scanning method to maintain a constant depth of laser focus within the wafer. This involves acquiring surface topography data of the wafer before formal processing using a ranging device and generating a static topography compensation table. During subsequent processing, the system dynamically adjusts the objective lens height in the Z-axis based on this compensation table.

[0003] Currently, during long-term continuous processing, the linear actuators (such as motion axes) of wafer continuous processing systems inevitably experience dynamic thermal deformation due to internal friction and increased ambient temperature. This nonlinear thermal deformation is superimposed on the system's mechanical structure, causing the actual optical focus to drift. Since the initial surface morphology data obtained before processing is static, it cannot detect and compensate for the dynamic height changes caused by thermal effects, ultimately leading to a deviation of the laser focus depth from the preset value, severely affecting the yield and dicing quality of wafer processing. Summary of the Invention

[0004] The problem this invention aims to solve is to provide a follow-up temperature rise compensation method for a wafer continuous processing system, addressing the aforementioned shortcomings in the prior art. This method overcomes the technical defects of the prior art, which relies on static ranging data and cannot cope with the thermal deformation of the linear actuator during processing. It can achieve high-precision dynamic closed-loop compensation for thermal drift of the linear motion module, structural design to avoid spatial interference, and minimization of coaxial linkage error, thereby significantly improving the focusing consistency and accuracy of laser processing.

[0005] The above-mentioned objective of this invention is achieved through the following technical solutions: A method for compensating for temperature rise in a wafer continuous processing system includes the following steps: S1: Prepare a wafer to be processed, scan the surface of the wafer using a rangefinder to obtain surface topography data of the wafer, and generate an initial height compensation model based on the surface topography data. S2: Processing is performed according to a preset path. When the workpiece moves to a preset distance measuring segment, the distance measuring device is triggered synchronously to collect the actual distance from the wafer surface to the workpiece within the distance measuring segment, which is recorded as the actual average distance d_real. S3: Based on the surface topography data obtained in S1, extract the coordinates of the planar region corresponding to the distance measurement segment in S2, and calculate the theoretical distance in the planar region coordinates under the condition that no thermal deformation has occurred, denoted as the theoretical average distance d_ideal; S4: Subtract the actual average distance d_real obtained in S2 from the theoretical average distance d_ideal obtained in S3 to obtain the thermal deformation difference value d_diff caused by temperature rise; S5: The thermal deformation difference value d_diff obtained in S4 is used as a dynamic compensation parameter and superimposed on the height compensation model of S1 in real time. This drives the workpiece to move an additional distance of d_diff along the height direction to offset the thermal deformation during the processing, thus forming a closed-loop focus height control.

[0006] Furthermore, the method further includes, S0: configuring a linear driver, a workpiece, and a ranging device in a group in a wafer continuous processing system, wherein the workpiece and the ranging device are disposed at the moving end of the linear driver.

[0007] Furthermore, the wafer is a silicon carbide wafer, the workpiece is a laser focusing objective lens, and the linear actuator is a motion platform.

[0008] Furthermore, the ranging device includes a transmitting unit and a receiving unit, which are respectively arranged on both sides of the processed part. The transmitting unit emits a ranging laser at a preset angle to the wafer surface. The receiving unit is equipped with an optical lens and a photoelectric sensor to receive the laser reflected from the wafer surface and calculate the height distance based on the displacement of the reflected light spot.

[0009] Furthermore, in S1, the surface morphology data is the height distribution data of the entire surface of the wafer, and the initial height compensation model is a pre-compensation table based on the static morphology.

[0010] Furthermore, in S2, the preset ranging segment consists of multiple ranging regions set at fixed intervals along the processing path, each ranging region having the same length, and the spacing between adjacent ranging segments being 0.5~2.0mm.

[0011] Furthermore, in S4, the thermal deformation difference value d_diff is used to characterize the amount of dynamic height drift caused by temperature rise during continuous machining of the linear actuator.

[0012] Furthermore, in S5, the additional distance the workpiece moves along the height direction is equal to the absolute value of d_diff but in the opposite direction, so that the laser focal depth formed by the workpiece inside the wafer is approximately at the same height.

[0013] Furthermore, in S5, after compensation, the processing depth deviation of the laser focus inside the wafer does not exceed 1 μm.

[0014] Furthermore, the method continuously and in a closed loop executes S2~S5 during the processing to compensate for the thermal deformation of the linear actuator in real time during the processing.

[0015] In summary, the beneficial technical effects of the present invention are as follows: 1. This invention collects the actual average distance from the wafer surface to the workpiece in real time during the processing, and calculates the difference between this and the theoretical average distance of the same area obtained before processing. The difference is then used as a dynamic compensation parameter and superimposed on the initial height compensation model in real time, driving the workpiece to move in the opposite direction of the height by the corresponding distance. This breaks through the limitations of the traditional static compensation strategy and can accurately offset the thermal drift of the drive mechanism during long-term continuous processing, controlling the focus depth deviation within 1μm and achieving high-precision dynamic closed-loop compensation. 2. Preferably, the transmitting and receiving units of the ranging device are located on opposite sides of the workpiece. The ranging is achieved based on the oblique reflection principle and the offset of the light spot position. This allows for high-precision measurement of the morphology of the processing area without interfering with the main processing optical path. At the same time, the ranging device and the workpiece are coaxially mounted on the same drive mechanism, which keeps the measurement coordinate system and the processing coordinate system physically rigidly bound together. This eliminates the mechanical synchronization error caused by independent drive, enabling real-time ranging in confined spaces. Furthermore, the thermal deformation difference can be directly equivalent to the workpiece compensation displacement, achieving efficient error control. 3. The method of the present invention first generates a static morphology compensation table by full-surface scanning before processing, and then sets ranging segments at fixed intervals along a preset path and triggers ranging synchronously during processing. The thermal deformation deviation of each ranging segment is calculated in real time and the objective lens height is adjusted through closed-loop feedback. This method can continuously and dynamically track and compensate for thermal drift throughout the entire processing process, which can significantly improve process stability, greatly improve the yield of ingot processing and cutting quality, and achieve good comprehensive application results. Attached Figure Description

[0016] Figure 1 This is a partial structural schematic diagram of the wafer continuous processing system of Embodiment 1 of the present invention.

[0017] Figure 2 This is a surface morphology data diagram of the wafer to be processed in Embodiment 1 of the present invention.

[0018] Figure 3 This is a schematic diagram of the processing path S2 in Embodiment 1 of the present invention.

[0019] Figure 4This is a graph showing the thermal deformation difference calculation data of S4 in Embodiment 1 of the present invention; wherein, the left column represents the distance (mm) between the current processing line and the bottom surface of the wafer; the left column represents the average distance measured (μm).

[0020] Figure 5 This is a comparison chart of the actual average distance and the theoretical average distance after enabling the follow-up temperature rise compensation in Embodiment 2 of the present invention.

[0021] Figure 6 This is a comparison chart of the actual average distance and the theoretical average distance after enabling the follow-up temperature rise compensation in Embodiment 3 of the present invention.

[0022] Figure 7 This is a comparison chart of the actual average distance and the theoretical average distance after the follow-up temperature rise compensation is turned off in Comparative Example 1 of this invention.

[0023] Figure 8 This is a comparison chart of the actual average distance and the theoretical average distance after the follow-up temperature rise compensation is turned off in Comparative Example 2 of this invention. Detailed Implementation

[0024] To make the technical means, creative features, objectives and effects of this invention clearer and easier to understand, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0025] Example 1: A method for compensating for temperature rise in a wafer continuous processing system disclosed in this invention includes the following steps: S0: Reference Figure 1 In a continuous wafer fabrication system, linear actuators, workpieces, and ranging devices are grouped together, with the workpieces and ranging devices located at the moving end of the linear actuators. The wafer is a silicon carbide wafer, the workpiece is a laser focusing objective lens, and the linear actuator is a motion platform. The ranging device includes a transmitting unit and a receiving unit, which are respectively arranged on both sides of the workpiece. The transmitting unit emits a ranging laser at a preset angle toward the wafer surface, and the receiving unit is equipped with an optical lens and a photoelectric sensor to receive the laser reflected from the wafer surface and calculate the height distance based on the displacement of the reflected light spot.

[0026] S1: Reference Figure 2 Prepare a wafer to be processed, scan the surface of the wafer with a rangefinder to obtain the height distribution data of the entire surface of the wafer, obtain the surface morphology data of the wafer, and generate a pre-compensation table based on static morphology based on the surface morphology data to obtain the initial height compensation model. S2: Reference Figure 3The process is carried out according to a preset path. Multiple measuring areas are set at fixed intervals along the processing path to form a measuring segment. Each measuring area has the same length, and the distance between adjacent measuring segments is 1.0 mm. When the workpiece moves to the preset measuring segment, the measuring device is triggered synchronously to collect the actual distance from the wafer surface to the workpiece within the measuring segment, which is recorded as the actual average distance d_real. S3: Based on the surface topography data obtained in S1, extract the coordinates of the planar region corresponding to the distance measurement segment in S2, and calculate the theoretical distance in the planar region coordinates under the condition that no thermal deformation has occurred, denoted as the theoretical average distance d_ideal; S4: Subtract the actual average distance d_real obtained from S2 from the theoretical average distance d_ideal obtained from S3 to obtain the thermal deformation difference value d_diff caused by temperature rise. The thermal deformation difference value d_diff is used to characterize the dynamic height drift of the linear actuator due to temperature rise during continuous processing. S5: Reference Figure 4 The thermal deformation difference value d_diff obtained from S4 is used as a dynamic compensation parameter and is superimposed on the height compensation model of S1 in real time. This drives the workpiece to move an additional distance of d_diff along the height direction. The additional distance of the workpiece along the height direction is equal to the absolute value of d_diff but in the opposite direction, so that the laser focus depth formed by the workpiece inside the wafer is approximately at the same height, thereby offsetting the thermal deformation during the processing and forming a closed-loop focus height control. After compensation, the processing depth deviation of the laser focus inside the wafer does not exceed 1μm. S6: Execute S2~S5 continuously and in a closed loop during the processing to compensate for the thermal deformation of the linear actuator in real time.

[0027] Example 2: This invention discloses a follow-up temperature rise compensation method for a wafer continuous processing system. The difference from Example 1 is that the wafer being processed is an 8-inch silicon carbide wafer with a total surface thickness variation (TTV) of approximately 30 μm. Follow-up temperature rise compensation processing was performed according to the method described in Example 1. During processing, the actual average distance d_real of each ranging segment was continuously collected and compared with the corresponding theoretical average distance d_ideal. The results are as follows... Figure 5 As shown, after enabling temperature rise compensation, the maximum deviation between the actual average distance and the theoretical average distance is less than 1 μm, indicating that the compensation method of the present invention can effectively counteract the thermal deformation caused by temperature rise and control the focal depth deviation within an extremely low range.

[0028] Example 3: This invention discloses a follow-up temperature rise compensation method for a continuous wafer fabrication system. The difference from Example 1 is that the wafer being processed is an 8-inch silicon carbide wafer with a total surface thickness variation (TTV) of approximately 13 μm. Follow-up temperature rise compensation processing was performed according to the method described in Example 1, and the results are as follows... Figure 6 As shown, after enabling temperature rise compensation, the maximum deviation between the actual average distance and the theoretical average distance is also less than 1 μm, further verifying the adaptability and compensation accuracy of this method for wafers with different surface morphologies.

[0029] Comparative Example 1: This invention discloses a follow-up temperature rise compensation method for a wafer continuous processing system. The difference from Example 2 is that, in step S6: S2-S5 are not executed during processing; that is, the actual distance during processing is not collected, the thermal deformation difference is not calculated, and follow-up temperature rise compensation is not performed. Processing is performed solely based on the static height compensation model generated in step S1. The processing results are as follows... Figure 7 As shown: when temperature rise compensation is turned off, the maximum deviation between the actual average distance and the theoretical average distance is about 10μm, the focal depth drifts significantly, and the processing consistency is poor.

[0030] Comparative Example 2: This is a follow-up temperature rise compensation method for a wafer continuous processing system disclosed in this invention. The difference from Example 3 is that, in step S6, steps S2-S5 are not executed during processing; that is, follow-up temperature rise compensation is not performed, and processing is carried out solely based on the static height compensation model. The processing results are as follows... Figure 8 As shown, when temperature rise compensation is turned off, the maximum deviation between the actual average distance and the theoretical average distance is also about 10μm, which further indicates that static compensation cannot cope with the dynamic height drift caused by the thermal deformation of the drive mechanism during continuous processing.

[0031] The above results show that, using the servo temperature rise compensation method provided by this invention (Examples 2 and 3), regardless of whether the wafer surface TTV is 30 μm or 13 μm, the focal depth deviation during processing can be controlled within 1 μm; while in Comparative Examples 1 and 2 without compensation, the focal depth deviation reaches approximately 10 μm. Therefore, this invention, by acquiring the actual distance in real time during processing and subtracting it from the theoretical distance, accurately extracts the thermal deformation difference value and feeds it back to the height compensation model in a closed loop, effectively offsetting the thermal drift of the drive mechanism and significantly improving the focal consistency and processing accuracy of laser processing.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for compensating for temperature rise in a wafer continuous processing system, characterized in that: Includes the following steps, S1: Prepare a wafer to be processed, scan the surface of the wafer using a rangefinder to obtain surface topography data of the wafer, and generate an initial height compensation model based on the surface topography data. S2: Processing is performed according to a preset path. When the workpiece moves to a preset distance measuring segment, the distance measuring device is triggered synchronously to collect the actual distance from the wafer surface to the workpiece within the distance measuring segment, which is recorded as the actual average distance d_real. S3: Based on the surface topography data obtained in S1, extract the coordinates of the planar region corresponding to the distance measurement segment in S2, and calculate the theoretical distance in the planar region coordinates under the condition that no thermal deformation has occurred, denoted as the theoretical average distance d_ideal; S4: Subtract the actual average distance d_real obtained in S2 from the theoretical average distance d_ideal obtained in S3 to obtain the thermal deformation difference value d_diff caused by temperature rise; S5: The thermal deformation difference value d_diff obtained in S4 is used as a dynamic compensation parameter and superimposed on the height compensation model of S1 in real time to drive the workpiece to move an additional distance of d_diff along the height direction to offset the thermal deformation during the processing and form a closed-loop focus height control. In S2, the preset ranging segment consists of multiple ranging areas set at fixed intervals along the processing path; In S5, the workpiece is a laser focusing objective lens.

2. The method for compensating for temperature rise in a wafer continuous processing system according to claim 1, characterized in that: The method further includes, S0: configuring a linear driver, a workpiece, and a ranging device in a group in a wafer continuous processing system, wherein the workpiece and the ranging device are disposed at the moving end of the linear driver.

3. The method for compensating for temperature rise in a wafer continuous processing system according to claim 2, characterized in that: The wafer is a silicon carbide wafer, and the linear actuator is a motion platform.

4. The method for compensating for temperature rise in a wafer continuous processing system according to claim 2, characterized in that: The ranging device includes a transmitting unit and a receiving unit, which are respectively arranged on both sides of the processed part. The transmitting unit emits a ranging laser at a preset angle to the wafer surface. The receiving unit is equipped with an optical lens and a photoelectric sensor to receive the laser reflected from the wafer surface and calculate the height distance based on the displacement of the reflected light spot.

5. The method for compensating for temperature rise in a wafer continuous processing system according to claim 1, characterized in that: In S1, the surface morphology data is the height distribution data of the entire surface of the wafer, and the initial height compensation model is a pre-compensation table based on the static morphology.

6. The method for compensating for temperature rise in a wafer continuous processing system according to claim 1, characterized in that: In S2, each ranging region has the same length, and the distance between adjacent ranging segments is 0.5~2.0mm.

7. The method for compensating for temperature rise in a wafer continuous processing system according to claim 1, characterized in that: In S4, the thermal deformation difference value d_diff is used to characterize the amount of dynamic height drift caused by temperature rise during continuous machining of the linear actuator.

8. The method for compensating for temperature rise in a wafer continuous processing system according to claim 1, characterized in that: In S5, the additional distance the workpiece moves along the height direction is equal to the absolute value of d_diff but in the opposite direction, so that the laser focal depth formed by the workpiece inside the wafer is approximately at the same height.

9. The method for compensating for temperature rise in a wafer continuous processing system according to claim 8, characterized in that: In S5, after compensation, the processing depth deviation of the laser focus inside the wafer does not exceed 1 μm.

10. The method for compensating for temperature rise in a wafer continuous processing system according to claim 1, characterized in that: The method continuously and in a closed loop executes S2~S5 during the processing to compensate for the thermal deformation of the linear actuator in real time.

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