Crystal cutting positioning system and method based on three-laser orthogonal distance measurement and tangent solution

Abstract

The invention discloses a crystal cutting positioning system and method based on three-laser orthogonal distance measurement and tangent calculation, and belongs to the field of precision machining of semiconductor crystal materials. The main structure of the system is as follows: three orthogonally arranged laser range finders are arranged on an objective table facing a crystal; a posture adjusting device is arranged below the objective table and used for adjusting the yaw angle and the pitch angle of the crystal. And the data processing module is used for receiving distance signals of the three laser range finders and calculating a yaw angle and a pitch angle of the crystal according to a tangent function relationship. According to the method, laser ranging micron-order resolution and fixed baseline geometric constraint are utilized, and the deviation of the yaw angle and the pitch angle is accurately quantified in combination with tangent function solution, so that coupling deviation decoupling is realized. And non-contact laser measurement is adopted, so that hard and brittle crystal damage is avoided. Laser sensing, high-speed processing and precise executing mechanisms are integrated, full-automatic rapid calibration is achieved, and the cutting preparation efficiency is improved. A real-time closed-loop control mechanism actively maintains the position and posture of the crystal before machining and / or during machining, dynamic interference is overcome, and the cutting quality stability is ensured.

Description

Technical Field

[0001] This invention relates to the field of precision machining of semiconductor crystal materials, and more particularly to a positioning system and method for precisely adjusting and determining the spatial pose (including pitch angle and horizontal yaw angle relative to the direction of travel of the cutting line) of a crystal on a cutting stage during crystal cutting processes (wire cutting, laser cutting, etc.). This invention is particularly applicable to wide-bandgap semiconductor crystal materials such as gallium oxide (Ga2O3), which have high hardness, high value, and extremely stringent requirements for crystal orientation accuracy during cutting. It aims to ensure that the cut surface of the crystal is strictly parallel to the large surface area of ​​the crystal through a non-contact, high-precision method, thereby improving material utilization and cutting quality. Background Technology

[0002] In the cutting process of semiconductor crystals such as gallium oxide, precise control of the crystal's spatial orientation on the stage is crucial to ensure that the cut crystal surface is the target crystal plane. The crystal's vertical plane (i.e., the vertical plane to which the cut surface is attached) must be strictly perpendicular to the stage's reference plane. Simultaneously, the crystal must be positioned in the horizontal plane so that the cut surface is parallel to the plane of travel of the cutting line (such as a diamond wire) (ensuring the cut surface is parallel to the large facet of the crystal). However, existing technologies mainly suffer from the following problems and shortcomings: Relying on human experience: Common methods such as visual observation combined with a simple level or mechanical clamps for rough alignment have low accuracy (usually only ±2° or lower), are easily affected by subjective factors, and cannot meet the accuracy requirements of high-value crystal materials.

[0003] Lack of coupling bias quantification: The pose bias of the crystal on the stage usually involves the coupling of pitch angle (affecting the verticality of the elevation) and horizontal yaw angle (affecting the parallelism between the cut surface and the large surface). Existing simple methods are difficult to quantify and decouple these two biases simultaneously and accurately.

[0004] Non-contact methods lack precision / contact methods carry risks: Some optical projection or 2D imaging technologies suffer from drawbacks such as cumbersome calibration, susceptibility to ambient light interference, and limited accuracy. Although contact probes offer relatively high precision, they still carry the risk of scratching or causing microcracks in hard and brittle crystals such as gallium oxide.

[0005] Unable to close the loop in real time: Traditional methods often use offline or static calibration. However, during the cutting process, factors such as vibration and thermal deformation can cause the calibrated pose to drift. The lack of real-time monitoring and dynamic compensation functions affects the final cutting quality.

[0006] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this invention is to provide a crystal cutting and positioning system and method based on three-laser orthogonal ranging and tangent function calculation, which aims to solve the problems of existing methods such as reliance on human experience, lack of coupling deviation quantification, insufficient non-contact accuracy / contact risk, and inability to close the loop in real time.

[0008] The technical solution of the present invention is as follows: A first aspect of the present invention provides a crystal cutting and positioning system based on three-laser orthogonal ranging and tangent calculation, wherein the system comprises: The crystal is placed on the stage. Facing the crystal, three orthogonally arranged laser rangefinders are mounted on the reference frame of the stage; The stage is equipped with an attitude adjustment device for adjusting the yaw and pitch angles of the crystal. The data processing module is used to receive distance signals from three laser rangefinders and calculate the yaw and pitch angles of the crystal based on the tangent function relationship. The comparison and generation module is used to compare the calculated yaw angle and pitch angle with the preset tolerance thresholds respectively; if the deviation of either angle exceeds the tolerance threshold, a control command is generated and sent to the attitude adjustment device; when the deviations of both angles are less than or equal to the tolerance threshold, a control command is generated and sent to the start cutting module.

[0009] Optionally, the attitude adjustment device is a piezoelectric ceramic micro-displacement platform or a tilting stage driven by a precision motor.

[0010] Optionally, two laser rangefinders are arranged horizontally with their measuring axes perpendicular to the plane of the cutting line movement, used to measure the distance values ​​d1 and d2 from the same crystal facet to the laser rangefinder at different horizontal heights; a third laser rangefinder is arranged perpendicularly to one of the two horizontally arranged laser rangefinders, used to measure the distance d3 from the target point to the laser rangefinder.

[0011] Optionally, the data processing module calculates the yaw angle φ=arctan(Δd / x) and the pitch angle θ=arctan((d1-d3) / h) using the tangent function relationship, where Δd is the difference between d1 and d2, x is the installation baseline distance between the two horizontal laser rangefinders, and h is the vertical baseline distance between the two vertical laser rangefinders.

[0012] A second aspect of the present invention provides a crystal cutting and positioning method based on three-laser orthogonal ranging and tangent calculation, wherein the system described in the present invention includes the following steps: Step 1: System initialization, calibrating the initial positional relationship of the laser rangefinder; Step 2: After placing the crystal to be cut, three laser rangefinders acquire distance signals in real time; Step 3: The data processing module receives distance signals from three laser rangefinders and calculates the yaw and pitch angles of the current crystal in real time based on the tangent function relationship. Step 4: Compare the calculated yaw angle and pitch angle with the preset tolerance thresholds respectively; if the deviation of either angle exceeds the tolerance range, generate a control command and send it to the attitude adjustment device, which adjusts the attitude of the crystal on the stage according to the yaw angle and pitch angle. Step 5: After adjustment, return to steps 2-3 to measure and calculate again until the deviation of both angles is less than or equal to the tolerance threshold. Step 6: When the deviation of both angles is less than or equal to the tolerance threshold, start the cutting process.

[0013] Optionally, the preset tolerance threshold is 0.1°.

[0014] Optionally, the crystal is a wide bandgap semiconductor crystal.

[0015] Optionally, the wide bandgap semiconductor crystal is a gallium oxide crystal.

[0016] Optionally, two laser rangefinders are arranged horizontally with their measuring axes perpendicular to the plane of the cutting line movement, used to measure the distance values ​​d1 and d2 from the same crystal facet to the laser rangefinder at different horizontal heights; a third laser rangefinder is arranged perpendicularly to one of the two horizontally arranged laser rangefinders, used to measure the distance d3 from the target point to the laser rangefinder.

[0017] Optionally, the data processing module calculates the yaw angle φ=arctan(Δd / x) and the pitch angle θ=arctan((d1-d3) / h) using the tangent function relationship, where Δd is the difference between d1 and d2, x is the installation baseline distance between the two horizontal laser rangefinders, and h is the vertical baseline distance between the two vertical laser rangefinders.

[0018] Compared with existing technologies, the crystal cutting and positioning system and method based on three-laser orthogonal ranging and tangent calculation provided by this invention have the following advantages: Significantly improved accuracy: By directly utilizing the micron-level resolution of laser ranging and the geometric constraints of a fixed baseline distance, combined with precise tangent function calculation, accurate quantitative measurement of spatial angular deviations (including yaw angle φ and pitch angle θ) is achieved. As a result, positioning accuracy has jumped dramatically from the traditional ±2° or higher to ±0.1° or even higher, thereby directly ensuring that the parallelism between the cut surface and the large surface of the crystal meets higher requirements.

[0019] Coupling Deviation Decoupling: The innovative orthogonal measurement structure and tangent calculation model achieve clear decoupling and quantification of coupled spatial deviations (i.e., yaw in the horizontal direction and pitch in the vertical direction) that are difficult to measure synchronously and accurately, providing clear data support for precise adjustment and effectively solving the core problems in the background technology.

[0020] Non-contact and highly reliable: The entire process uses non-contact laser measurement technology, which completely avoids the risk of scratching or causing microcracks to hard and brittle crystals such as gallium oxide by contact probes (achieving zero damage guarantee) and ensuring high reliability of measurement.

[0021] High speed and high degree of automation: The system integrates laser sensing, high-speed processing and precision actuators, realizing fully automatic and rapid calibration (reducing the minutes required for traditional manual calibration to tens of seconds), significantly improving the efficiency of cutting preparation.

[0022] Achieving closed-loop control: The closed-loop control mechanism of real-time measurement, calculation and adjustment can actively maintain the crystal pose before and / or during processing (optional), overcome the limitations of static calibration methods, effectively resist dynamic interferences such as vibration and thermal drift during processing (achieved through real-time feedback compensation), and further ensure the stability of the final cutting quality.

[0023] Significant cost-effectiveness: For high-value ingots such as gallium oxide (whose cost far exceeds that of silicon), higher cutting parallelism and yield can not only significantly reduce material scrap rate (i.e., reduce wafer breakage rate), but also improve material utilization, thereby bringing significant economic benefits. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of crystal cutting.

[0025] Figure 2 This is a diagram showing the position distribution of the three laser spots of the laser rangefinder.

[0026] Figure 3 This is a top view of the laser rangefinder and the crystal position.

[0027] Figure 4 This is a left-side view showing the position of the laser rangefinder and the crystal.

[0028] Figure 5 This is a flowchart illustrating the crystal cutting and positioning method based on three-laser orthogonal ranging and tangent calculation according to the present invention.

[0029] Explanation of reference numerals in the attached figures: 1, 2, and 3 represent the light spots formed on the crystal surface by the lasers emitted by laser rangefinder 1, laser rangefinder 2, and laser rangefinder 3, respectively. L is the actual horizontal distance between spot 1 and spot 2, and H is the actual vertical distance between spot 1 and spot 3; x is the installation baseline distance between the two horizontal laser rangefinders, and h is the vertical baseline distance between the two vertical laser rangefinders. Detailed Implementation

[0030] This invention provides a crystal cutting and positioning system and method based on three-laser orthogonal ranging and tangent calculation. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0031] This invention provides a positioning system and method for precisely adjusting and determining the spatial pose (including pitch angle and horizontal yaw angle relative to the cutting line direction) of a crystal on a cutting stage during crystal cutting processes (wire cutting, laser cutting, etc.). This positioning system and method are particularly suitable for wide-bandgap semiconductor crystal materials such as gallium oxide (Ga2O3), which have high hardness, high value, and extremely stringent requirements for crystal orientation accuracy. The aim is to ensure that the cut surface is strictly parallel to the large surface area of ​​the crystal through a non-contact, high-precision method, thereby improving material utilization and cutting quality. The positioning system and method of this invention are described in detail below.

[0032] Please combine Figures 1-2 This invention provides a crystal cutting and positioning system based on three-laser orthogonal ranging and tangent calculation, comprising: The crystal is placed on the stage. Facing the crystal, three orthogonally arranged laser rangefinders are mounted on the reference frame of the stage; The stage is equipped with an attitude adjustment device for adjusting the yaw and pitch angles of the crystal. The data processing module is used to receive distance signals from three laser rangefinders and calculate the yaw and pitch angles of the crystal based on the tangent function relationship. The comparison and generation module is used to compare the calculated yaw angle and pitch angle with the preset tolerance thresholds respectively; if the deviation of either angle exceeds the tolerance threshold, a control command is generated and sent to the attitude adjustment device; when the deviations of both angles are less than or equal to the tolerance threshold, a control command is generated and sent to the start cutting module.

[0033] It should be noted that the data processing module, comparison and generation module, and cutting start module in the system of this embodiment can be integrated into various crystal wire cutting machines or laser cutting equipment.

[0034] Key structure of this invention embodiment: Facing the crystal to be cut, three laser rangefinders (also called laser range sensors) are set up. The crystal is placed on a stage, and an attitude adjustment device is provided below the stage to adjust the pitch and yaw angles (i.e., horizontal rotation angles) of the crystal. The three high-precision laser rangefinders are orthogonally arranged (i.e., at 90-degree angles to each other) on the reference frame of the cutting stage. Specifically, two laser rangefinders (laser rangefinder 1 and laser rangefinder 2) are arranged horizontally, with their measuring axes perpendicular to the plane of the cutting line. These two rangefinders are used to measure the distances d1 and d2 from the same crystal surface at different horizontal heights (or more specifically, two points) to the laser rangefinders. The third laser rangefinder (laser rangefinder 3) is arranged vertically and is used to measure the distance d3 from the target point to the laser rangefinder. This data is used to help determine the horizontal deflection angle φ of the surface.

[0035] Combination Figures 2-4 The measurement principle and pose decoupling of embodiments of the present invention will be introduced as follows: Yaw angle (horizontal parallelism deviation): The key lies in using two horizontally opposed laser rangefinders 1 and 2. Calculate the difference in readings between the two laser rangefinders, Δd = |d1 - d2|. Since the installation baseline distance x between the two laser rangefinders is fixed and precisely known, when the crystal facet is parallel to the baseline (i.e., the cutting line travel plane), d1 = d2, Δd = 0. When a yaw angle φ exists, the crystal facet is not parallel to the line connecting 1 and 2, resulting in d1 ≠ d2. According to the simple tangent trigonometric function relationship: tan(φ) ≈ Δd / x, the yaw angle φ can be calculated using φ = arctan(Δd / x). By adjusting the yaw angle using an attitude adjustment device, the crystal facet can be kept parallel to the cutting plane.

[0036] Pitch angle (vertical deviation of the facade): This can be achieved by combining a vertical laser rangefinder 3 with a single horizontal laser rangefinder (such as laser rangefinder 1). Similarly, the pitch angle θ can be calculated as arctan((d1-d3) / h), where h is the preset vertical baseline distance. By adjusting the pitch angle using the attitude adjustment device, the crystal facade can be kept parallel to the cutting plane.

[0037] The attitude adjustment device can be a piezoelectric ceramic micro-displacement platform or a tilting stage driven by a precision motor. Depending on different accuracy and load requirements, the attitude adjustment device can also be a precision slide stage or tilting platform driven by a voice coil motor or servo motor to obtain greater stroke and load-bearing capacity, thereby enabling the system to adapt to the processing needs of crystals of different sizes and weights and expanding the application range of the system.

[0038] Compared with the prior art, the main improvements of the embodiments of the present invention are as follows: Orthogonal Tri-Laser Structure: This innovative system employs three orthogonally arranged laser rangefinders to achieve non-contact direct measurement of distances to specific crystal planes. Tangent Function Decoupling: Utilizing a simple tangent function (θ = arctan((d1-d3) / h), φ = arctan(Δd / x)), the difference in distance measurements is directly and clearly calculated into critical pitch and yaw angle deviations, effectively achieving precise quantification of spatial coupling angle deviations. Non-Contact High-Precision Measurement: The laser rangefinder possesses micron-level (±0.5μm or even higher) displacement resolution. Combined with a baseline distance h (e.g., 50mm), even minute Δd changes can be detected (approximately 0.0011°), achieving angle control accuracy of ±0.1° or even higher. 4. Real-Time and Closed-Loop Control: The system can perform high-speed sampling (e.g., millisecond-level), calculate angle deviations in real time, and drive precision actuators for dynamic adjustments, thus forming a closed-loop control mechanism.

[0039] 5. Anti-interference (optional): Differential measurement, signal processing algorithms (such as filtering, reference point compensation) or hardware design (such as protective cover) can be used to improve stability in factory environments (such as vibration, air disturbance, etc.).

[0040] 6. Application Scenarios: In the (100) facet cutting of β-Ga2O3 crystals, this system can quickly (e.g., within 30 seconds) stably control the yaw angle φ and pitch angle θ deviation of the ingot on the stage within ±0.1°, ensuring that the final cut surface is highly parallel to the large facet of the crystal. This system can be integrated into various crystal wire cutting machines or laser cutting equipment.

[0041] Combination Figure 5 As shown, this embodiment of the invention provides a crystal cutting and positioning method based on three-laser orthogonal ranging and tangent calculation. The system described above, applied according to this embodiment, includes the following steps: Step 1: System initialization, calibrating the initial positional relationship of the laser rangefinder; Step 2: After placing the crystal to be cut, three laser rangefinders acquire distance signals d1, d2 and d3 in real time; Step 3: The data processing module receives distance signals from three laser rangefinders and calculates the yaw angle φ (horizontal parallelism deviation) and pitch angle θ (verticality deviation) of the current crystal in real time based on the tangent function relationship. Step 4: Compare the calculated angle deviations (θ, φ) with the preset tolerance thresholds (e.g., ±0.1°); if any angle deviation exceeds the tolerance range, generate the corresponding control command and send it to the attitude adjustment device (e.g., piezoelectric ceramic micro-displacement platform or precision motor-driven tilt stage) to precisely adjust the attitude of the crystal on the stage according to the direction and value of θ and φ. Step 5: After adjustment, return to Steps 2-3 to measure and calculate again until the deviation of the two angles is less than or equal to the tolerance threshold (i.e., meets the tolerance requirements). Step 6: When the deviations of both angles are less than or equal to the tolerance threshold (i.e., the pose is qualified), the cutting process is started. Depending on actual needs (optional), continuous monitoring or intermittent monitoring can be performed during the cutting process.

[0042] This method is implemented through hardware architecture, encompassing core technologies such as mathematical principles and algorithmic know-how. A vibration pre-compensation algorithm injects reverse displacement, and dual-wavelength lasers penetrate the surface atomization layer, improving the stability of the laser spot positioning by five times, thereby advancing the control precision of the crystal cutting angle to sub-0.1°. In cost-sensitive and highly precision-required applications like gallium oxide, this represents an industrial-grade leap from "experience-based calibration" to "mathematically deterministic control."

[0043] In summary, this invention provides a crystal cutting and positioning system and method based on three-laser orthogonal ranging and tangent calculation. By employing three orthogonally arranged laser rangefinders, non-contact direct measurement of the distance to a specific surface of the crystal is achieved. Using simple tangent functions (θ = arctan((d1-d3) / h), φ = arctan(Δd / x)), the difference in ranging values ​​is directly and clearly calculated into the critical pitch and yaw angle deviations, effectively achieving precise quantification of spatial coupling angle deviations. The laser rangefinders possess micron-level (±0.5μm or even higher) displacement resolution. Combined with a baseline distance h (e.g., 50mm), even a small Δd can detect significant angle changes (approximately 0.0011°), achieving angle control accuracy of ±0.1° or even higher. The system can perform high-speed sampling (e.g., millisecond-level), calculate angle deviations in real time, and drive precision actuators for dynamic adjustments, thus forming a closed-loop control mechanism. This system can quickly (within 30 seconds) stabilize the yaw angle φ and pitch angle θ deviation of the crystal ingot on the stage within ±0.1°, ensuring that the final cut surface is highly parallel to the large surface of the crystal. This system can be integrated into various crystal wire cutting machines or laser cutting equipment.

[0044] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A crystal cutting and positioning system based on three-laser orthogonal ranging and tangent calculation, characterized in that, include: The crystal is placed on the stage. Facing the crystal, three orthogonally arranged laser rangefinders are mounted on the reference frame of the stage; The stage is equipped with an attitude adjustment device for adjusting the yaw and pitch angles of the crystal. The data processing module is used to receive distance signals from three laser rangefinders and calculate the yaw and pitch angles of the crystal based on the tangent function relationship. The comparison and generation module is used to compare the calculated yaw angle and pitch angle with the preset tolerance thresholds respectively; if the deviation of either angle exceeds the tolerance threshold, a control command is generated and sent to the attitude adjustment device; when the deviations of both angles are less than or equal to the tolerance threshold, a control command is generated and sent to the start cutting module.

2. The crystal cutting and positioning system based on three-laser orthogonal ranging and tangent calculation according to claim 1, characterized in that, The attitude adjustment device is a piezoelectric ceramic micro-displacement platform or a tilting platform driven by a precision motor.

3. The crystal cutting and positioning system based on three-laser orthogonal ranging and tangent calculation according to claim 1, characterized in that, Two laser rangefinders are arranged horizontally with their measuring axes perpendicular to the plane of the cutting line. They are used to measure the distances d1 and d2 from the same crystal facet at different horizontal heights to the laser rangefinders. A third laser rangefinder is arranged perpendicularly to one of the two horizontally arranged laser rangefinders and is used to measure the distance d3 from the target point to the laser rangefinder.

4. The crystal cutting and positioning system based on three-laser orthogonal ranging and tangent calculation according to claim 3, characterized in that, The data processing module calculates the yaw angle φ=arctan(Δd / x) and the pitch angle θ=arctan((d1-d3) / h) using the tangent function relationship, where Δd is the difference between d1 and d2, x is the installation baseline distance between the two horizontal laser rangefinders, and h is the vertical baseline distance between the two vertical laser rangefinders.

5. A crystal cutting and positioning method based on three-laser orthogonal ranging and tangent calculation, characterized in that, The system according to any one of claims 1-2 includes the following steps: Step 1: System initialization, calibrating the initial positional relationship of the laser rangefinder; Step 2: After placing the crystal to be cut, three laser rangefinders acquire distance signals in real time; Step 3: The data processing module receives distance signals from three laser rangefinders and calculates the yaw and pitch angles of the current crystal in real time based on the tangent function relationship. Step 4: Compare the calculated yaw angle and pitch angle with the preset tolerance thresholds respectively; if the deviation of either angle exceeds the tolerance range, generate a control command and send it to the attitude adjustment device, which adjusts the attitude of the crystal on the stage according to the yaw angle and pitch angle. Step 5: After adjustment, return to steps 2-3 to measure and calculate again until the deviation of both angles is less than or equal to the tolerance threshold. Step 6: When the deviation of both angles is less than or equal to the tolerance threshold, start the cutting process.

6. The crystal cutting and positioning method based on three-laser orthogonal ranging and tangent calculation according to claim 5, characterized in that, The preset tolerance threshold is 0.1°.

7. The crystal cutting and positioning method based on three-laser orthogonal ranging and tangent calculation according to claim 5, characterized in that, The crystal is a wide bandgap semiconductor crystal.

8. The crystal cutting and positioning method based on three-laser orthogonal ranging and tangent calculation according to claim 7, characterized in that, The wide bandgap semiconductor crystal is gallium oxide crystal.

9. The crystal cutting and positioning method based on three-laser orthogonal ranging and tangent calculation according to claim 5, characterized in that, Two laser rangefinders are arranged horizontally with their measuring axes perpendicular to the plane of the cutting line. They are used to measure the distances d1 and d2 from the same crystal facet at different horizontal heights to the laser rangefinders. A third laser rangefinder is arranged perpendicularly to one of the two horizontally arranged laser rangefinders and is used to measure the distance d3 from the target point to the laser rangefinder.

10. The crystal cutting and positioning method based on three-laser orthogonal ranging and tangent calculation according to claim 9, characterized in that, The data processing module calculates the yaw angle φ=arctan(Δd / x) and the pitch angle θ=arctan((d1-d3) / h) using the tangent function relationship, where Δd is the difference between d1 and d2, x is the installation baseline distance between the two horizontal laser rangefinders, and h is the vertical baseline distance between the two vertical laser rangefinders.

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