Wafer thinning processing control method, control system and processing equipment
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI IND U TECH RES INST
- Filing Date
- 2024-09-29
- Publication Date
- 2026-07-24
Smart Images
Figure CN119057573B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of wafer thinning processing technology, and in particular to a wafer thinning processing control method, control system and processing equipment. Background Technology
[0002] During operation, the spindle with grinding wheels rotates at a certain speed and gradually descends. The grinding wheels on the spindle contact the wafer to remove the silicon on the wafer. The spindle is lifted up when the built-in wafer thickness measuring device detects that the wafer thickness has reached the set value, and the grinding wheels disengage from the wafer, thus stopping the thinning process.
[0003] The aforementioned processing control method determines whether wafer processing is complete by real-time detection of wafer thickness, thereby controlling whether the spindle stops descending. During this process, if the thickness detection device malfunctions (especially contact-type thickness detection devices within the machine, which have a higher probability of failure), and the wafer thickness reading remains unchanged, and if the reported wafer thickness reading does not reach the target value (i.e., the wafer thickness value used to indicate that processing is complete and the spindle should stop descending), the spindle will continue to descend. This could lead to over-grinding of the wafer due to the spindle's erroneous descent. Since wafer processing requires high precision, even a small amount of over-grinding can result in wafer scrap. Therefore, preventing wafer scrap due to thickness detection device malfunction is a pressing issue that needs to be addressed. Summary of the Invention
[0004] One objective of the first aspect of this invention is to provide a wafer thinning process control method that can prevent wafers from being scrapped due to over-grinding caused by malfunctions in the thickness detection device.
[0005] Another objective of this invention is to improve the accuracy of wafer thinning.
[0006] A further objective of this invention is to make the displacement correction factor more accurate.
[0007] A second aspect of the present invention is to provide a wafer thinning control system for performing the above-described wafer thinning control method.
[0008] A third aspect of the present invention is to provide a processing apparatus including the above-described wafer thinning processing control system.
[0009] An embodiment of the present invention provides a wafer thinning process control method, comprising:
[0010] Obtain the initial thickness and real-time thickness of the currently processed wafer;
[0011] Obtain the downward movement of the grinding wheel spindle when the last processing was completed;
[0012] Calculate the change in the downward movement of the grinding wheel spindle and the change in the thickness of the wafer at the end of each processing cycle;
[0013] The real-time downward displacement threshold of the grinding wheel spindle is calculated based on the initial thickness, the real-time thickness, the downward displacement of the grinding wheel spindle when the previous processing was completed, the change values of each downward displacement, and the change values of each thickness.
[0014] The grinding wheel spindle is stopped when the real-time downward movement of the grinding wheel spindle is greater than or equal to the real-time downward movement threshold.
[0015] Furthermore, the real-time downward threshold is calculated according to the following formula:
[0016]
[0017] Where n is the number of processing times, A n h is the real-time downward threshold for the nth processing iteration. n-1 h is the downward displacement of the grinding wheel spindle when the (n-1)th processing is completed. i-1 h is the downward displacement of the grinding wheel spindle when the (i-1)th processing is completed. i-2 Let h0 be the downward movement of the grinding wheel spindle when the (i-2)th processing step is completed, T(i-1) be the wafer thickness when the (i-1)th processing step is completed, T0(i-1) be the initial wafer thickness before the (i-1)th processing step, h0 be the downward movement of the grinding wheel spindle when the grinding wheel spindle contacts the wafer during the first processing step, and T be the downward movement of the grinding wheel spindle. 0n Let t be the initial thickness of the wafer before the nth processing step. n The real-time thickness of the wafer during the nth processing stage.
[0018] Furthermore, when calculating the real-time downward displacement threshold, the displacement correction coefficient is used to correct the formula. The displacement correction coefficient is determined based on the wear prediction error of the grinding wheel spindle and the rate of change of the downward displacement difference of the grinding wheel spindle during each processing.
[0019] Furthermore, the displacement correction factor is determined according to the following formula:
[0020]
[0021] Where, α n As The multiplication factors of the term, β1 and β2 are weighting coefficients, B′ n-1 C represents the predicted wear of the grinding wheel spindle during the (n-1)th processing cycle. n-1 The processing displacement change rate of the grinding wheel spindle during the (n-1)th processing is the amount of downward movement of the grinding wheel spindle from the moment the grinding wheel spindle contacts the wafer during a single processing step until the completion of that processing step.
[0022] Furthermore, the sum of β1 and β2 is 1, and β1 is less than β2.
[0023] Furthermore, when the real-time downward movement of the grinding wheel spindle is less than the real-time downward movement threshold, the grinding wheel spindle is controlled to descend until the wafer reaches the target thickness.
[0024] Furthermore, when the real-time downward movement of the grinding wheel spindle is greater than or equal to the real-time downward movement threshold, an alarm signal is generated and sent to the warning unit.
[0025] Embodiments of the present invention also provide a wafer thinning process control system, including a memory and a processor, wherein the memory stores a control program, and the control program, when executed by the processor, is used to implement the wafer thinning process control method described above.
[0026] Embodiments of the present invention also provide a wafer thinning processing apparatus, comprising:
[0027] Wafer thickness detection unit, used to detect the thickness of wafers;
[0028] A displacement detection unit is used to detect the downward movement of the grinding wheel spindle; and
[0029] The wafer thinning process control system described above is connected to both the wafer thickness detection unit and the displacement detection unit.
[0030] Furthermore, the wafer thinning processing equipment also includes an alarm unit connected to the wafer thinning processing control system, which alarms upon receiving an alarm signal.
[0031] According to a first aspect of the present invention, a real-time downward displacement threshold for the grinding wheel spindle can be calculated based on the initial and real-time thickness of the wafer being processed, the downward displacement of the grinding wheel spindle at the end of the previous processing, the changes in each downward displacement, and the changes in each thickness. This real-time downward displacement threshold is then compared with the real-time downward displacement of the grinding wheel spindle. If the real-time downward displacement exceeds the real-time downward displacement threshold, the grinding wheel spindle is immediately stopped. Therefore, during a single processing cycle, the real-time downward displacement of the grinding wheel spindle is always limited by a threshold, ensuring that even if a wafer thickness detection failure occurs during processing, the grinding wheel spindle will not over-grind, thereby reducing the wafer processing scrap rate.
[0032] According to a second aspect of the present invention, when calculating the real-time downward displacement threshold, the present application considers the predicted wear change rate and the actual displacement change rate of the grinding wheel spindle. The actual displacement change rate can directly reflect the wear change rate of the grinding wheel. These two factors form a displacement correction coefficient, which corrects the reference value of the grinding wheel wear in the current processing in the real-time downward displacement threshold calculation formula, making the reference value more accurate and able to reflect the wear change law and the processing displacement change law. This makes the downward displacement control of the grinding wheel spindle more accurate and is conducive to improving the accuracy of wafer thinning.
[0033] Furthermore, setting the weighting coefficient of the predicted wear change rate to be smaller than the weighting coefficient of the actual displacement change rate can avoid over-reliance on the correction of single prediction errors, strengthen the actual displacement change rate that can directly reflect the wear state, and make the displacement correction coefficient more accurate. Attached Figure Description
[0034] Figure 1 This is a flowchart of a wafer thinning process control method according to an embodiment of the present invention;
[0035] Figure 2 This is a flowchart of a wafer thinning process control method according to another embodiment of the present invention. Detailed Implementation
[0036] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.
[0037] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application's specification are for illustrative purposes only and do not represent the only possible implementation.
[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0039] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0040] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items.
[0041] Figure 1 This is a flowchart of a wafer thinning process control method according to an embodiment of the present invention. Figure 1 As shown, in one embodiment, the wafer thinning process control method includes the following steps:
[0042] Step S100: Obtain the initial thickness and real-time thickness of the currently processed wafer;
[0043] Step S200: Obtain the downward movement of the grinding wheel spindle when the previous processing was completed;
[0044] Step S300: Calculate the change in the downward movement of the grinding wheel spindle and the change in the thickness of the wafer when each processing is completed;
[0045] Step S400: Calculate the real-time downward displacement threshold of the grinding wheel spindle based on the initial thickness, real-time thickness, the downward displacement of the grinding wheel spindle when the previous processing was completed, the change values of each downward displacement, and the change values of each thickness.
[0046] Step S500: When the real-time downward movement of the grinding wheel spindle is greater than or equal to the real-time downward movement threshold, control the grinding wheel spindle to stop.
[0047] In step S100, the wafer thickness can be acquired using a wafer thickness detection unit, such as a non-contact optical thickness gauge, a capacitive thickness gauge, or an ultrasonic thickness gauge, or other commonly used thickness detection devices. In step S200, a grating ruler can be used to measure the downward movement of the grinding wheel spindle.
[0048] In step S400, the initial and real-time thickness of the wafer are closely related to the downward movement control of the grinding wheel spindle. As the real-time thickness decreases, it means the downward movement allowance of the grinding wheel spindle gradually shrinks. The downward movement of the grinding wheel spindle at the end of the previous processing run can serve as the basis for the wear amount of the grinding wheel during the current processing. The changes in each downward movement and each thickness can reflect the wear patterns during historical processing. Therefore, based on these values, the limit for the downward movement of the grinding wheel spindle during the current processing run can be determined, i.e., the real-time downward movement threshold.
[0049] This application calculates the real-time downward movement threshold of the grinding wheel spindle based on the initial and real-time thickness of the wafer being processed, the downward movement of the grinding wheel spindle after the previous processing, the changes in each downward movement, and the changes in each thickness. Then, it compares this real-time downward movement threshold with the real-time downward movement of the grinding wheel spindle. If the real-time downward movement exceeds the threshold, the grinding wheel spindle is immediately stopped. Therefore, during a single processing cycle, the real-time downward movement of the grinding wheel spindle is always limited by a threshold, ensuring that even if a wafer thickness detection failure occurs during processing, the grinding wheel spindle will not over-grind, thereby reducing the wafer processing scrap rate.
[0050] In one embodiment, the real-time downshift threshold is calculated according to the following formula (1):
[0051]
[0052] Where n is the number of processing times, A n h is the real-time shift threshold for the nth processing iteration. n-1 h is the downward movement of the grinding wheel spindle when the (n-1)th machining cycle is completed. i-1 h represents the downward movement of the grinding wheel spindle when the (i-1)th machining cycle is completed. i-2 Let h0 be the downward movement of the grinding wheel spindle after the (i-2)th processing step, T(i-1) be the wafer thickness after the (i-1)th processing step, T0(i-1) be the initial wafer thickness before the (i-1)th processing step, h0 be the downward movement of the grinding wheel spindle when it contacts the wafer during the first processing step, and T be the depth of the wafer. 0n Let t be the initial thickness of the wafer before the nth processing step. n The real-time thickness of the wafer during the nth processing stage.
[0053] This application provides a specific calculation formula for the real-time downshift threshold. This formula is based on the downshift amount of the grinding wheel spindle when the previous processing was completed, plus the average of the difference between the downshift amounts of the grinding wheel spindle when two adjacent processing were completed, which serves as a reference value for the wear of the grinding wheel in the current processing. In addition, a term related to the real-time thickness of the wafer during the current processing is added, so that the real-time downshift threshold can change with the real-time thickness of the wafer. This allows the real-time downshift threshold to adapt to the entire processing process in real time when the grinding wheel spindle moves down, thereby limiting the downshift amount of the grinding wheel spindle and effectively preventing over-grinding of the wafer.
[0054] In a further embodiment, when calculating the real-time downward threshold, the displacement correction coefficient is used to correct the formula. The displacement correction coefficient is determined based on the prediction error of the wear amount of the grinding wheel spindle and the rate of change of the difference in the downward displacement of the grinding wheel spindle during each processing cycle. In one embodiment, the displacement correction coefficient is determined according to the following formulas (2) and (3):
[0055]
[0056] Where β1 and β2 are weighting coefficients, B ′ n-1 C represents the predicted wear of the grinding wheel spindle during the (n-1)th machining operation. n-1 C5 represents the rate of change of the machining displacement of the grinding wheel spindle during the (n-1)th machining operation. The machining displacement is the amount of downward movement of the grinding wheel spindle from the moment it contacts the wafer during a single machining operation until the end of that operation. For example, when n = 6, C5 = (X5 - X4) / X4, where X5 is the amount of downward movement of the grinding wheel spindle from the moment it contacts the wafer during the 5th machining operation until the end of the operation, and X4 is the amount of downward movement of the grinding wheel spindle from the moment it contacts the wafer during the 4th machining operation until the end of the operation.
[0057] In this embodiment, the displacement correction factor α is... n As The multiplication factor of the term, therefore the corrected real-time downshift threshold is determined according to the following formula (4):
[0058]
[0059] In one embodiment, the sum of β1 and β2 is 1, and β1 is less than β2. Optionally, β1 is a value between 0.1 and 0.4, and β2 is a value between 0.5 and 1, for example, β1 is 0.3 and β2 is 0.7, or β1 is 0.2 and β2 is 0.8.
[0060] The above calculation of the real-time downward movement threshold takes into account the predicted wear rate and the actual displacement rate of the grinding wheel spindle. The actual displacement rate directly reflects the wear rate of the grinding wheel. These two factors form a displacement correction coefficient, which corrects the reference value of the grinding wheel wear in the current processing in the real-time downward movement threshold calculation formula, making the reference value more accurate and able to reflect the wear change law and the processing displacement change law. This makes the downward movement control of the grinding wheel spindle more accurate and helps to improve the accuracy of wafer thinning.
[0061] Furthermore, setting the weighting coefficient of the predicted wear change rate to be smaller than the weighting coefficient of the actual displacement change rate can avoid over-reliance on the correction of single prediction errors, strengthen the actual displacement change rate that can directly reflect the wear state, and make the displacement correction coefficient more accurate.
[0062] Figure 2 This is a flowchart of a wafer thinning process control method according to another embodiment of the present invention. Figure 2 As shown, in another embodiment,
[0063] Step S300 includes:
[0064] Step S310: Obtain the downward movement of the abrasive spindle at the completion of each machining operation in the historical machining process;
[0065] Step S320: Obtain the initial thickness of the wafer at the start of each processing step in the historical processing process and the processing thickness of the wafer at the end of the processing step;
[0066] Step S330: Calculate the change in downward movement based on the downward movement of the abrasive spindle at the end of each processing step in the historical processing process; calculate the change in wafer thickness based on the initial thickness of the wafer at the start of each processing step in the historical processing process and the processing thickness of the wafer at the end of processing.
[0067] The process after step S400 also includes:
[0068] Step S450: Determine whether the real-time downward movement of the grinding wheel spindle is less than the real-time downward movement threshold. If yes, proceed to step S600; otherwise, proceed to step S520.
[0069] In step S600, control the grinding wheel spindle to descend until the wafer reaches the target thickness.
[0070] Step S520: Control the grinding wheel spindle to stop, generate an alarm signal, and send the alarm signal to the warning unit so that the warning unit can sound an alarm.
[0071] This application also provides a wafer thinning process control system, including a memory and a processor. The memory stores a control program, which, when executed by the processor, is used to implement the wafer thinning process control method in any of the above embodiments.
[0072] The processor can be a central processing unit (CPU). The processor can also be other general-purpose control modules, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations of the above types of chips.
[0073] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as the movement trajectory adjustment method in this embodiment of the invention. The control module executes various functional applications and data processing, i.e., the movement trajectory adjustment method, by running the non-transitory software programs, instructions, and modules stored in the memory.
[0074] The memory may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created by the control module, etc. Furthermore, the memory may include high-speed random access memory and non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory may optionally include memory remotely located relative to the control module, and these remote memories can be connected to the control module via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.
[0075] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium can also include combinations of the above types of memory.
[0076] This application also provides a wafer thinning processing equipment, including a wafer thickness detection unit, a displacement detection unit, an alarm unit, and the aforementioned wafer thinning processing control system. The wafer thickness detection unit is used to detect the thickness of the wafer. The displacement detection unit is used to detect the downward movement of the grinding wheel spindle. The wafer thinning processing control system is connected to both the wafer thickness detection unit and the displacement detection unit. The alarm unit is connected to the wafer thinning processing control system and alarms upon receiving an alarm signal. The alarm unit can be a display screen, speaker, warning light, or other common warning devices used to alert processing personnel to processing malfunctions.
[0077] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A method for controlling wafer thinning processing, characterized in that, include: Obtain the initial thickness and real-time thickness of the currently processed wafer; Obtain the downward movement of the grinding wheel spindle when the last processing was completed; Calculate the change in the downward movement of the grinding wheel spindle and the change in the thickness of the wafer at the end of each processing cycle; The real-time downward displacement threshold of the grinding wheel spindle is calculated based on the initial thickness, the real-time thickness, the downward displacement of the grinding wheel spindle when the previous processing was completed, the change values of each downward displacement, and the change values of each thickness. When the real-time downward movement of the grinding wheel spindle is greater than or equal to the real-time downward movement threshold, the grinding wheel spindle is controlled to stop. The real-time downshift threshold is calculated according to the following formula: ； Where n is the number of processing steps. The real-time downward shift threshold during the nth processing iteration. It is the downward displacement of the grinding wheel spindle when the (n-1)th processing is completed. The downward movement of the grinding wheel spindle is the amount of downward movement when the (i-1)th processing is completed. This represents the downward movement of the grinding wheel spindle when the (i-2)th processing step is completed. The thickness of the wafer is when the (i-1)th processing step is completed. The initial thickness of the wafer before the (i-1)th processing step. The amount of downward movement of the grinding wheel spindle when it contacts the wafer during the initial processing. Let be the initial thickness of the wafer before the nth processing step. The real-time thickness of the wafer during the nth processing step; When calculating the real-time downward threshold, the displacement correction coefficient is used to correct the formula. The displacement correction coefficient is determined based on the wear prediction error of the grinding wheel spindle and the rate of change of the downward displacement difference of the grinding wheel spindle during each processing.
2. The wafer thinning process control method according to claim 1, characterized in that, The displacement correction factor is determined according to the following formula: ； ； in, As Multiplicative factors of the term, , These are the weighting coefficients. The predicted wear amount of the grinding wheel spindle during the (n-1)th processing cycle is given. The processing displacement change rate of the grinding wheel spindle during the (n-1)th processing is the amount of downward movement of the grinding wheel spindle from the moment the grinding wheel spindle contacts the wafer during a single processing step until the completion of that processing step.
3. The wafer thinning process control method according to claim 2, characterized in that, and The sum is 1 and Less than .
4. The wafer thinning process control method according to any one of claims 1-3, characterized in that, When the real-time downward movement of the grinding wheel spindle is less than the real-time downward movement threshold, the grinding wheel spindle is controlled to descend until the wafer reaches the target thickness.
5. The wafer thinning process control method according to any one of claims 1-3, characterized in that, An alarm signal is generated and sent to the warning unit when the real-time downward movement of the grinding wheel spindle is greater than or equal to the real-time downward movement threshold.
6. A wafer thinning process control system, characterized in that, The device includes a memory and a processor, wherein the memory stores a control program, which, when executed by the processor, is used to implement the wafer thinning process control method according to any one of claims 1-5.
7. A wafer thinning processing equipment, characterized in that, include: Wafer thickness detection unit, used to detect the thickness of wafers; The displacement detection unit is used to detect the downward movement of the grinding wheel spindle; as well as The wafer thinning process control system of claim 6 is connected to both the wafer thickness detection unit and the displacement detection unit.
8. The wafer thinning processing equipment according to claim 7, characterized in that, It also includes an alarm unit, which is connected to the wafer thinning process control system and alarms when an alarm signal is received.