Method for vertical calibration of a lithography system, storage medium and lithography system

Abstract

The application discloses a vertical measurement and calibration method of a photolithography machine system, a storage medium and the photolithography machine system. The method comprises the following steps: focusing and leveling subsystem initialization, moving the workpiece table in the opposite horizontal direction to make the center peak of the center measurement light spot disappear basically, so as to determine two critical positions, and then calculate and accurately position the calibration origin. At the calibration origin, the workpiece table is controlled to execute movement and record the change of the light spot measurement value, and the calibration relationship between the light spot measurement value and the vertical displacement of the workpiece table is established. Starting from the calibration origin, the workpiece table is controlled to move to a plurality of symmetrically distributed measurement points along a preset path, and the light spot measurement values of the points are collected. Based on the measurement values, the measurement change amount of the wafer in two orthogonal directions is calculated, and the calibration relationship is used to convert the measurement change amount into the height change amount of the workpiece table, and then the tilt amount of the workpiece table, the compensation of the driving adjustment motor are solved, so that the high-precision measurement and calibration of the workpiece table are realized.

Description

Technical Field

[0001] This application relates to a vertical calibration method for a lithography machine system, a storage medium, and a lithography machine system, belonging to the field of lithography calibration technology. Background Technology

[0002] As a core semiconductor manufacturing device that precisely transfers mask patterns onto wafers, the imaging accuracy of a lithography machine directly determines the performance of the chip. Within a lithography machine, the Focus-Leveling System (FLS) is crucial for ensuring clear imaging across the entire exposure field. This system measures the positional and orientation deviations between the silicon wafer surface and the optimal focal plane of the projection lens in real time, and drives the stage to perform leveling and focusing compensation.

[0003] However, the measurement accuracy of the focusing and leveling system itself is a prerequisite for its performance. After initial installation, maintenance, or long-term operation, misalignment may occur between the optical measurement zero point and the optimal focal plane of the projection lens. Simultaneously, the calibration relationship between the system's output measurement signal value and the actual vertical physical displacement of the workpiece stage may also drift. Without a high-precision, repeatable, and reliable calibration method to calibrate and correct these system errors, even if the FLS system itself is stable, the inaccuracy of its measurement reference will directly lead to errors in subsequent leveling and focusing operations, resulting in defocusing or tilting of the entire wafer, causing pattern defects, and severely reducing product yield.

[0004] Existing calibration methods or technical solutions typically have the following limitations: 1) Insufficient accuracy in determining the calibration origin: The method for determining the measurement reference origin is relatively crude, often relying on mechanical positioning or rough optical alignment. The accuracy is limited and easily affected by the operator's subjective judgment, resulting in poor repeatability of calibration.

[0005] 2) The calibration process is cumbersome and not closed-loop: The calibration process consists of multiple isolated, manual steps, with low automation and low efficiency. Furthermore, it lacks a closed-loop iterative mechanism of measurement-calculation-compensation-verification, making it impossible to ensure that the calibration results eventually converge to the optimal state.

[0006] 3) Weak anti-interference and error isolation capabilities: When calculating the system tilt, the layout of measurement points and data processing algorithms used fail to effectively isolate or offset common mode errors (such as environmental micro-vibration and measurement noise) and interference introduced by the surface undulations of the workpiece being measured, resulting in impure and unstable system errors in the calibration.

[0007] Therefore, there is an urgent need in this field for a vertical calibration method for lithography machines that can achieve high precision, high repeatability, automation and strong anti-interference capability, so as to accurately establish and maintain the mapping relationship between the measurement values ​​of the focusing and leveling subsystem and the actual position and orientation of the workpiece stage, and provide a solid and reliable measurement benchmark for the lithography process. Summary of the Invention

[0008] In view of this, this application provides a vertical calibration method for a lithography machine system, a storage medium, and a lithography machine system. The embodiments of this application aim to solve the problems of low calibration accuracy, poor repeatability, cumbersome process, and insufficient anti-interference ability in related technologies.

[0009] The first aspect of this application discloses a vertical calibration method for a lithography machine system. The lithography machine system includes a focusing and leveling system, a workpiece stage, and a wafer. The wafer is placed on the chuck of the workpiece stage. The method includes: S101 After the focusing and leveling system is installed, the vertical position of the measuring zero point of the focusing and leveling system is made consistent with the vertical position of the actual optimal focal plane of the projection lens. S102 moves the workpiece stage to the zero position of the center spot along the vertical direction, and records the first measured value of the center spot of the focusing and leveling system and the first motion state of the workpiece stage. S103 controls the workpiece stage to move along the first horizontal direction, so that the central peak of the central light spot basically disappears, records the second motion state of the workpiece stage, controls the workpiece stage to move along the second horizontal direction, so that the central peak of the central light spot basically disappears, records the third motion state of the workpiece stage, the first horizontal direction being opposite to the second horizontal direction; S104 determines the calibration origin position based on the second motion state and the third motion state; S105 determines the calibration relationship between the change in the center spot measurement value of the focusing and leveling subsystem and the change in the motion state of the workpiece stage. S106 Starting from the calibration origin position, control the workpiece stage to move along a preset path to multiple measurement points, and record multiple second measurement values ​​of the center spot of the focusing and leveling system. S107 calculates the measurement change of the wafer in two mutually orthogonal directions based on the plurality of second measurement values; S108 converts the measured change into a change in workpiece stage height based on the calibration relationship; S109 calculates the tilt of the workpiece stage based on the change in workpiece stage height; S110 controls the adjustment motor of the workpiece stage to compensate for the tilt of the workpiece stage, and repeats steps S106 to S110 until the tilt of the workpiece stage is less than the threshold.

[0010] In some embodiments, controlling the workpiece stage to move along a first horizontal direction so that the central peak of the central light spot essentially disappears, and recording the second motion state of the workpiece stage, includes: S1031 controls the workpiece stage to move from the first motion state along the first horizontal direction with a first preset step size until the light intensity hC0 of the central peak is less than a preset value, and records the position of the workpiece stage as the first critical state. S1032 controls the workpiece stage to move from the first critical state along the first horizontal direction with a second preset step size until the central peak completely disappears. The position of the workpiece stage is recorded as the second critical state. The workpiece stage is then controlled to move from the second critical state along the second horizontal direction to an intermediate state. The light intensity hC2 of the central peak in the intermediate state is recorded. The intermediate state is located at the midpoint between the first critical state and the second critical state. The first preset step size is greater than the second preset step size. S1033 Determine whether the light intensity hC2 satisfies the condition: hC2≤(hC0) / m, where m is an integer greater than or equal to 2; If S1034 is satisfied, then the intermediate state is determined as the second motion state; If S1035 is not satisfied, then a step size smaller than the current second preset step size is used, and steps S1032 to S1035 are re-executed with the current intermediate state as the starting point of movement, until a new intermediate state that satisfies the above conditions is found and it is determined as the second motion state.

[0011] In some embodiments, determining the calibration origin position based on the second motion state and the third motion state includes: S1041 Calculate the coordinates of the midpoint of the line connecting the coordinates of the second motion state and the coordinates of the third motion state; S1042 calculates the distance from the midpoint to the theoretical calibration point along the direction perpendicular to the connecting line based on the radius of the wafer, the coordinates of the midpoint, and the coordinates of the third motion state, according to geometric relationships. S1043 controls the workpiece stage to move the distance to the theoretical calibration point; S1044, based on the theoretical calibration point, controls the workpiece stage to perform local scanning in the first horizontal direction and the horizontal direction perpendicular to the first horizontal direction, records the measured values ​​of the center spot at multiple discrete positions on the scanning path and calculates the average value, and determines the coordinates of the calibration origin position based on the average value and the correspondence between the measured value and the coordinates. S1045 controls the workpiece stage to move to the calibration origin position.

[0012] In some embodiments, the preset path is to move from the calibration origin position along a spiral or grid path from the inside to the outside on the surface of the wafer.

[0013] In some embodiments, the plurality of measurement points include at least a plurality of points symmetrically distributed in the horizontal and vertical directions around the location of the calibration origin.

[0014] In some embodiments, calculating the measurement change of the wafer in two mutually orthogonal directions based on the plurality of second measurement values ​​includes calculating the measurement change δHx_wcs in the X direction and the measurement change δHy_wcs in the Y direction, specifically implemented by the following formula:

[0015] Wherein, H(Bxx) represents the second measurement value recorded at the corresponding measurement point Bxx.

[0016] In some embodiments, the plurality of measurement points include eight measurement points, which are set based on a Cartesian coordinate system with the calibration origin as the origin, wherein the first horizontal axis is the X-axis and the second horizontal axis is the Y-axis; The first measurement point (B10) and the fifth measurement point (B20) are located on the X-axis and are symmetrical about the origin. The distance from both to the origin is a first set distance Dx. The third measurement point (B01) and the seventh measurement point (B02) are located on the Y-axis and are symmetrical about the origin. The distance from both to the origin is the second set distance Dy. The second measurement point (B11) and the sixth measurement point (B12) are symmetrical about the X-axis and are located in the first quadrant and the fourth quadrant, respectively. The distance from the second measurement point (B11) to the Y-axis is a first set distance Dx, and the distance to the X-axis is a second set distance Dy. The fourth measurement point (B21) and the eighth measurement point (B22) are symmetrical about the X-axis and are located in the second quadrant and the third quadrant, respectively. The distance from the fourth measurement point (B21) to the Y-axis is a first set distance Dx, and the distance to the X-axis is a second set distance Dy.

[0017] In some embodiments, calculating the workpiece stage tilt includes calculating the tilt in the X direction δRx_wscs and the tilt in the Y direction δRy_wscs.

[0018] A second aspect of this application discloses a computer-readable storage medium comprising a stored program, wherein the program, when running, controls the execution of the vertical calibration method of the lithography system described above in the processor of the device.

[0019] A third aspect of this application discloses a lithography machine system, wherein the computer device includes a processor and a memory; wherein the memory stores a computer program adapted to be loaded by the processor and executed by the processor to perform the vertical calibration method of the lithography machine system described above.

[0020] Compared with the prior art, the embodiments of this application have the following beneficial effects: (1) The embodiments of this application realize high-precision closed-loop calibration at the system level: a rigorous measurement-feedback-correction closed loop is constructed through a complete and automated process from zero-position alignment, precise origin positioning, establishment of calibration relationship to iterative compensation verification. This ensures the initial accuracy and long-term stability of the focusing and leveling system as the eye of the lithography machine, thus guaranteeing the quality of the exposure pattern from the source.

[0021] (2) The embodiments of this application significantly improve the accuracy and repeatability of motion state: by controlling the horizontal movement of the workpiece stage to make the center peak of the light spot basically disappear, a specific optical boundary detection method is used, combined with a coarse-to-fine search strategy and a clear light intensity threshold criterion, to achieve objective, accurate and repeatable positioning of motion state, effectively eliminating the uncertainty caused by human intervention.

[0022] (3) The embodiments of this application have excellent anti-interference and error isolation capabilities: (3-1) The embodiments of this application use an ultra-flat wafer (a wafer with extremely high surface flatness) as a reference: it fundamentally isolates the interference of the deformation of the workpiece (silicon wafer) itself on the calibration process, so that the calibration result purely reflects the performance of the measurement system and the workpiece stage motion mechanism.

[0023] (3-2) The embodiments of this application adopt symmetrical point layout and differential calculation: By symmetrically distributing multiple measurement points around the origin (such as the specific 8-point method, which can take efficiency into account) and the corresponding differential calculation formula, the common mode noise and system zero drift in the measurement process can be effectively offset, thereby extracting the error component that reflects the true tilt of the system with high fidelity.

[0024] (4) The embodiments of this application improve the automation and efficiency of the calibration process: the entire method has clear steps, strong logic, and is easy to achieve fully automated operation through controller programming. In particular, the iterative compensation (S110) automatically brings the system to the optimal state, reducing the dependence on senior operators and improving the usability and maintenance efficiency of the equipment.

[0025] (5) The embodiments of this application have direct output and clear interface: the final output is the physical tilt amount of the workpiece stage in the X and Y directions that can be directly used for drive compensation. The interface with the lithography machine control system is clear, which facilitates the quick and accurate execution of correction actions. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0027] Figure 1 A simplified flowchart of the vertical calibration method for a lithography system provided in this application embodiment.

[0028] Figure 2 A flowchart illustrating the vertical calibration method for a lithography system provided in this application embodiment.

[0029] Figure 3 This is a schematic diagram showing the distribution of N measurement spots in the focusing and leveling system provided in this application embodiment.

[0030] Figure 4 This is a schematic diagram showing the change in light intensity of spot 1 of the focusing and leveling system with position when at the zero position, as provided in an embodiment of this application.

[0031] Figure 5 This is a schematic diagram showing the change in light intensity of spot 1 of the focusing and leveling system as the position changes when the central peak disappears, as provided in the embodiments of this application.

[0032] Figure 6a This is a schematic diagram of the positive and negative X-axis motion of the workpiece stage edge provided in the embodiments of this application.

[0033] Figure 6b This is a schematic diagram of the workpiece stage motion under the coarse-to-fine search strategy provided in the embodiments of this application.

[0034] Figure 7 This is a layout diagram of multiple measurement points symmetrically distributed around the origin, provided for an embodiment of this application.

[0035] Figure 8 This is a layout diagram of eight measurement points symmetrically distributed around the origin, provided for an embodiment of this application. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0037] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0038] Example 1: like Figure 1 and Figure 2 As shown, Figure 1 and Figure 2 A flowchart illustrating a vertical calibration method for a lithography system provided in this application embodiment. This vertical calibration method for a lithography system includes the following steps: Step 0: After the focusing and leveling system is installed, ensure that the vertical position of the measuring zero point of the focusing and leveling system is consistent with the vertical position of the actual optimal focal plane of the projection lens.

[0039] like Figure 3 As shown, the focusing and leveling system measures N light spots. In this embodiment, N=5, and light spot 1 represents the center light spot. The vertical direction is the Z-direction.

[0040] Step 1: Place a wafer on the stage chuck. Move the stage along the Z-axis to the zero position of spot 1. Record the measurement result H11 of spot 1 at this point. Figure 4 As shown. And, record the first motion state A1(X11, Y11, Z11) of the workpiece stage at this time.

[0041] Step Two: Move horizontally (X-direction, X-direction, Y-direction, and Y-direction are not in any particular order) to the position where the center peak of spot number 1 in the focusing and leveling system disappears, such as... Figure 5 As shown. Furthermore, record the second motion state A2(X22, Y11, Z11) of the workpiece stage at this time. (As shown...) Figure 6a and Figure 6b As shown, the specific steps are as follows: S21: The workpiece stage moves from A1 along the positive X direction to the first critical state C0 (XC0, Y11, Z11), that is, the light intensity hC0 corresponding to the center peak of spot No. 1 is less than the threshold T0.

[0042] S22: The workpiece stage moves from C0 along the positive X direction with a small step size δx1 to the second critical state C1 (XC1, Y11, Z11), that is, the central peak of spot No. 1 completely disappears.

[0043] S23: The workpiece stage moves from C1 along the negative X direction to the current intermediate state C2 ((XC0+XC1) / 2, Y11, Z11), and records the light intensity hC2 corresponding to the center peak of spot 1 at this time.

[0044] S24: If hC2≤(hC0) / m, m≥2 and m is a positive integer, then the intermediate state position is A2, A2=C2. If hC2>(hC0) / m, execute S25.

[0045] S25: The workpiece stage moves from C2 to state C1 in the positive X direction with a smaller step size δx2 (where δx2 < δx1), and then moves from C1 to C3 ((XC2 + XC1) / 2, Y11, Z11) in the negative X direction. Record the light intensity hC3 corresponding to the center peak of spot 1 at this time.

[0046] S26: If hC3≤(hC0) / m, m≥2 and m is a positive integer, then the intermediate state position is A2, A2=C3. If hC3>(hC0) / m, execute S27.

[0047] S27: The workpiece stage moves from C3 to state C1 in the positive X direction with a smaller step size δx3 (where δx3 < δx2), and then moves from C1 to C4 ((XC3 + XC1) / 2, Y11, Z11) in the negative X direction. Record the light intensity hC4 corresponding to the center peak of spot 1 at this time.

[0048] S28: If hC4≤(hC0) / m, m≥2 and m is a positive integer, then the intermediate state position is A2, A2=C4. If hC4>(hC0) / m, the loop continues.

[0049] Until the light intensity corresponding to the center peak of spot 1 is ≤ (hC0) / m, the workpiece stage position is A2(X22, Y11, Z11).

[0050] It is worth noting that the parameters m and threshold T0 need to be set by technicians according to the actual situation. In the above loop, the step size is reduced accordingly after each iteration, so that the determined intermediate state position gradually approaches the edge of the wafer.

[0051] Step 3: The workpiece stage moves horizontally again to the position where the center peak of spot 1 in the focusing and leveling system disappears (repeat step 2, but in the opposite direction). Figure 6a As shown. Furthermore, record the motion state of the workpiece stage at this time, A3(X33, Y11, Z11).

[0052] Step 4: Move the workpiece stage to the calibration origin position, such as... Figure 6a As shown, the specific steps are as follows: S41: Determine the midpoint A4(X440, Y11, Z11) between A2 and A3, where X44 = (X22 + X33) / 2.

[0053] S42: Determine the distance between A4 and the theoretical position O_0 (X440, Y440, Z11) of the calibration origin as follows: , Where R is the radius of the wafer.

[0054] S43: The workpiece stage moves a distance d11 along the negative Y direction to position O_0.

[0055] S44: The workpiece stage moves along the X direction from O_1 (X440-g0, Y440, Z11) to O_2 (X440+g0, Y440, Z11) in steps δe. Record the measurement values ​​h(δe11), h(δe12), h(δe13), ... of the focusing and leveling spot 1 at each step. S45: The workpiece stage moves along the Y-axis from O_3(X440, Y440-g0, Z11) to O_4(X440, Y440+g0, Z11) in steps δe. Record the measurement values ​​h(δe21), h(δe22), h(δe23), ... of the focusing and leveling spot 1 at each step. S46: Calculate the average value h(δe_mean) of the focusing and leveling spot 1 measured in S44 and S45.

[0056] S47: The workpiece stage moves to the corresponding position in S46, namely O(X44, Y44, Z11).

[0057] In S47, similar to the method in step two, the workpiece stage moves along the X and Y directions with a fixed step size of δee (δe<δee) using the correspondence between the measured value and the coordinates until it moves to a certain position. At this position, the difference between the measured value of the focusing and leveling spot 1 and h(δe_mean) is less than the set threshold. The coordinates of this position are the coordinates of the calibration origin.

[0058] It is worth noting that g0, δe, and δee are all very small quantities, and g0 > δe > δee; step S46 calculates the average value of the height of the focusing and leveling spot 1.

[0059] Step 5: Determine the relationship between the change in the measurement value of focusing and leveling spot 1 and the change in the motion state of the workpiece stage. The specific steps are as follows: S51: The workpiece stage moves to O1 (X44, Y44, Z11-S11).

[0060] S52: The workpiece stage moves gradually from O1 along the Z direction until it reaches O2 (X44, Y44, Z11+S11), for a total of m steps. Each step is δS11. The change in the measurement value of the focusing and leveling spot No. 1 at each step is as follows:

[0061] S53: Polynomial fitting of the relationship between δH(m,1) and δS11:

[0062] S54: Set the threshold T1 for the fitting coefficient, based on R... 2 T1 determines the order n of S53 and calculates the various parameters. a 0, a 1, a 2, ..., a n 1.

[0063] Step Six: Starting from O, the workpiece stage moves sequentially from the inside to the outside in a counter-clockwise (or clockwise) direction, as follows. Figure 7 As shown. Specific movement routes can be selected according to the specific circumstances.

[0064] In this embodiment, the workpiece stage starts from O and moves sequentially to B10(X55, Y44, Z11), B11(X55, Y55, Z11), B01(X44, Y55, Z11), B21(X66, Y55, Z11), B20(X66, Y44, Z11), B22(X66, Y66, Z11), B02(X44, Y66, Z11), and B12(X55, Y66, Z11), as shown. Figure 8 As shown. And, record the corresponding focusing and leveling spot 1 measurement values ​​H(B10), H(B11), H(B01), H(B21), H(B20), H(B22), H(B02), H(B12).

[0065] Step 7: Calculate the changes in the measured values ​​of the wafer, δHx_wcs and δHy_wcs, respectively: .

[0066] Step 8: Using the parameters from Step 5, calculate the changes in workpiece stage height δHx_wscs and δHy_wscs: .

[0067] Step 9: Calculate the workpiece stage tilt amounts δRx_wscs and δRy_wscs: .

[0068] Step Ten: The workpiece stage adjustment motor compensates for the tilt amounts δRx_wscs and δRy_wscs in Step Nine.

[0069] Repeat Steps Six to Ten until the tilt amounts of the workpiece stage are both less than the thresholds δRx_wscs < T2 and δRy_wscs < T2.

[0070] Embodiment 2: The embodiment of the present application further provides a lithography machine system, including: a memory storing an executable program; a processor for running the program, wherein when the program runs, it executes the methods in various embodiments of the present invention.

[0071] The above-mentioned memory may refer to a device inside a computer for storing data and programs, which may include a memory, a hard disk, etc. Among them, the memory can be used for temporarily storing running programs and data, and the hard disk can be used for long-term storing programs and data. The memory can be used to enable the computer to read and write data, and execute programs; the above-mentioned processor can be responsible for executing instructions in the computer program and performing data processing, and can be responsible for controlling and executing various operations, including arithmetic operations, logical operations, data transmission, etc.

[0072] Embodiment 3: The embodiment of the present application further provides a computer-readable storage medium, which includes a stored executable program, wherein when the executable program runs, it controls the device where the computer-readable storage medium is located to execute the methods in various embodiments of the present invention.

[0073] The above-mentioned computer storage medium may refer to a medium in a computer memory for storing a certain discontinuous physical quantity. The computer storage medium mainly includes semiconductors, magnetic cores, magnetic drums, magnetic tapes, laser discs, etc.; the stored program included in the computer-readable storage medium can be a set of instructions that a computer can recognize and execute, running on an electronic computer, and is an information-based tool to meet people's certain needs.

[0074] Embodiment 4: The embodiment of the present application further provides a computer program product, including a computer program, and when the computer program is executed by a processor, it implements the methods in various embodiments of the present invention.

[0075] The above-mentioned computer program product may refer to a software program that has been written, tested and released, and can run on a computer or other devices. The computer program product can include application programs, operating systems, tool software, etc., and is used to implement specific functions or solve specific problems.

[0076] Embodiment 5: Embodiments of this application also provide a computer program product, including a non-volatile computer-readable storage medium for storing a computer program that, when executed by a processor, implements the methods in various embodiments of the present invention.

[0077] The aforementioned non-volatile computer-readable storage medium can refer to a medium for storing data. Non-volatile computer-readable storage media can retain data without loss when power is off and can be used to store long-term data, such as operating systems, applications, and user files. Non-volatile storage media can include hard disk drives, solid-state drives, optical disks, and flash memory storage devices, etc.

[0078] Example 6: Embodiments of this application also provide a computer program that, when executed by a processor, implements the methods described in the various embodiments of the present invention.

[0079] The aforementioned computer program can refer to a set of instructions used to tell the computer to perform specific tasks or operations. Computer programs can be written by programmers using specific programming languages ​​and can include algorithms, data structures, logic, and control flow. Computer programs can be used for a variety of purposes, including application software, operating systems, etc.

[0080] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0081] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0082] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0083] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0084] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0085] In summary, the vertical calibration method for lithography machines described in this invention successfully addresses the core pain points of existing technologies, such as low calibration accuracy, poor repeatability, and weak anti-interference capabilities, through a set of logically rigorous and interconnected automated steps. It provides a crucial and reliable measurement benchmark for achieving long-term stable ultra-high-precision imaging of lithography machines, and has significant value for improving the yield and process stability of high-end semiconductor manufacturing.

[0086] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A vertical calibration method for a lithography machine system, the lithography machine system comprising a focusing and leveling system, a workpiece stage, and a wafer, wherein the wafer is placed on a chuck of the workpiece stage, characterized in that, The method includes: S101 After the focusing and leveling system is installed, the vertical position of the measuring zero point of the focusing and leveling system is made consistent with the vertical position of the actual optimal focal plane of the projection lens. S102 moves the workpiece stage to the zero position of the center spot along the vertical direction, and records the first measured value of the center spot of the focusing and leveling system and the first motion state of the workpiece stage. S103 controls the workpiece stage to move along the first horizontal direction, so that the central peak of the central light spot basically disappears, records the second motion state of the workpiece stage, controls the workpiece stage to move along the second horizontal direction, so that the central peak of the central light spot basically disappears, records the third motion state of the workpiece stage, the first horizontal direction being opposite to the second horizontal direction; S104 determines the calibration origin position based on the second motion state and the third motion state; S105 determines the calibration relationship between the change in the center spot measurement value of the focusing and leveling subsystem and the change in the motion state of the workpiece stage. S106 Starting from the calibration origin position, control the workpiece stage to move along a preset path to multiple measurement points, and record multiple second measurement values ​​of the center spot of the focusing and leveling system. S107 calculates the measurement change of the wafer in two mutually orthogonal directions based on the plurality of second measurement values; S108 converts the measured change into a change in workpiece stage height based on the calibration relationship; S109 calculates the tilt of the workpiece stage based on the change in workpiece stage height; S110 controls the adjustment motor of the workpiece stage to compensate for the tilt of the workpiece stage, and repeats steps S106 to S110 until the tilt of the workpiece stage is less than the threshold.

2. The vertical calibration method according to claim 1, characterized in that, The control of the workpiece stage to move along a first horizontal direction, causing the central peak of the central light spot to essentially disappear, and the recording of the second motion state of the workpiece stage, includes: S1031 controls the workpiece stage to move from the first motion state along the first horizontal direction with a first preset step size until the light intensity hC0 of the central peak is less than a preset value, and records the position of the workpiece stage as the first critical state. S1032 controls the workpiece stage to move from the first critical state along the first horizontal direction with a second preset step size until the central peak completely disappears. The position of the workpiece stage is recorded as the second critical state. The workpiece stage is then controlled to move from the second critical state along the second horizontal direction to an intermediate state. The light intensity hC2 of the central peak in the intermediate state is recorded. The intermediate state is located at the midpoint between the first critical state and the second critical state. The first preset step size is greater than the second preset step size. S1033 Determine whether the light intensity hC2 satisfies the condition: hC2≤(hC0) / m, where m is an integer greater than or equal to 2; If S1034 is satisfied, then the intermediate state is determined as the second motion state; If S1035 is not satisfied, then a step size smaller than the current second preset step size is used, and steps S1032 to S1035 are re-executed with the current intermediate state as the starting point of movement, until a new intermediate state that satisfies the above conditions is found and it is determined as the second motion state.

3. The vertical calibration method according to claim 1, characterized in that, Determining the calibration origin position based on the second motion state and the third motion state includes: S1041 Calculate the coordinates of the midpoint of the line connecting the coordinates of the second motion state and the coordinates of the third motion state; S1042 calculates the distance from the midpoint to the theoretical calibration point along the direction perpendicular to the connecting line based on the radius of the wafer, the coordinates of the midpoint, and the coordinates of the third motion state, according to geometric relationships. S1043 controls the workpiece stage to move the distance to the theoretical calibration point; S1044, based on the theoretical calibration point, controls the workpiece stage to perform local scanning in the first horizontal direction and the horizontal direction perpendicular to the first horizontal direction, records the measured values ​​of the center spot at multiple discrete positions on the scanning path and calculates the average value, and determines the coordinates of the calibration origin position based on the average value and the correspondence between the measured value and the coordinates. S1045 controls the workpiece stage to move to the calibration origin position.

4. The vertical calibration method according to claim 1, characterized in that, The preset path is to start from the calibration origin and move along a spiral or grid path from the inside to the outside on the surface of the wafer.

5. The vertical calibration method according to claim 4, characterized in that, The plurality of measurement points include at least a plurality of points symmetrically distributed in the horizontal and vertical directions around the location of the calibration origin.

6. The vertical calibration method according to claim 1, characterized in that, Based on the plurality of second measurement values, the measurement change of the wafer in two mutually orthogonal directions is calculated, including the measurement change δHx_wcs in the X direction and the measurement change δHy_wcs in the Y direction, specifically implemented by the following formula: Wherein, H(Bxx) represents the second measurement value recorded at the corresponding measurement point Bxx.

7. The vertical calibration method according to claim 6, characterized in that, The plurality of measurement points includes eight measurement points, which are set based on a plane rectangular coordinate system with the calibration origin as the origin, wherein the first horizontal axis is the X-axis and the second horizontal axis is the Y-axis; The first measurement point (B10) and the fifth measurement point (B20) are located on the X-axis and are symmetrical about the origin. The distance from both to the origin is a first set distance Dx. The third measurement point (B01) and the seventh measurement point (B02) are located on the Y-axis and are symmetrical about the origin. The distance from both to the origin is the second set distance Dy. The second measurement point (B11) and the sixth measurement point (B12) are symmetrical about the X-axis and are located in the first quadrant and the fourth quadrant, respectively. The distance from the second measurement point (B11) to the Y-axis is a first set distance Dx, and the distance to the X-axis is a second set distance Dy. The fourth measurement point (B21) and the eighth measurement point (B22) are symmetrical about the X-axis and are located in the second quadrant and the third quadrant, respectively. The distance from the fourth measurement point (B21) to the Y-axis is a first set distance Dx, and the distance to the X-axis is a second set distance Dy.

8. The vertical calibration method according to claim 1, characterized in that, The calculation of the workpiece stage tilt includes calculating the tilt amount δRx_wscs in the X direction and the tilt amount δRy_wscs in the Y direction.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the vertical calibration method as described in any one of claims 1 to 8.

10. A lithography machine system, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the vertical calibration method as described in any one of claims 1 to 8.

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