Method and equipment for preparing sub-arc-second gradient substrate through ion beam etching

Abstract

The invention provides a method and equipment for preparing a sub-arc-second gradient substrate through ion beam etching. The method comprises the following steps: determining the relationship between the residence time and the etching depth when an ion beam is used for etching a substrate, so as to form a first model; determining the etching amount distribution of the substrate along the etching path of the ion beam according to the processing target of the substrate; determining the relationship between the speed and the acceleration of the ion beam and the time when the ion beam carries out etching along the etching path, so as to form a second model; determining residence time distribution according to the etching amount distribution and a first model; according to the residence time distribution and a second model, determining speed distribution and acceleration distribution of ion beam etching along time; and controlling the ion beam to etch the etching path according to the speed distribution and the acceleration distribution. According to the method, the processing formula of ion beam etching is formed through the speed distribution and the acceleration distribution, the target etching depth can be obtained through the residence time, and reliable processing of the sub-arc-second gradient substrate is realized.

Description

Technical Field

[0001] This application relates to the field of subarcsecond graded substrate fabrication technology. Specifically, this application relates to a method and apparatus for fabricating subarcsecond graded substrates by ion beam etching. Background Technology

[0002] Subarcsecond graded-gradient substrates refer to basic materials with subarcsecond graded slopes. Examples include optical glass and wafers. Subarcsecond refers to an angle greater than 0.1 arcseconds but less than 1 arcsecond. Taking optical glass as an example, it is the most fundamental and critical component in precision optical systems. Its geometric accuracy and optical uniformity directly determine the imaging quality and diffraction requirements of subsequent optical systems. Especially for high-performance optical systems, the substrate surface needs to maintain extremely high parallelism. Although an angle difference of ten to tens of arcseconds between the front and rear surfaces of the substrate is sufficient for conventional high-precision optical substrates, for optical substrates required in high-end manufacturing, even an error of several arcseconds will cause significant beam deflection and phase distortion. Furthermore, in addition to controlling the parallelism during processing, high-performance optical glass also requires the fabrication of graded film thickness structures within the subarcsecond range to achieve precise control of the beam's phase leading edge by altering the optical thickness distribution. For example, in optical communication and optical filtering devices, radially graded structures are used to achieve optical path compensation or equalize different channels; in lens correction and freeform surface optics, graded film thickness is used to correct aberrations or compensate for non-uniformity in transmission systems; in optical testing and interferometry, graded films can be used to achieve reference phase modulation, etc. Therefore, reliable fabrication of sub-arcsecond graded substrates is a technical challenge that urgently needs to be solved in high-precision substrate fabrication.

[0003] While existing technologies can fabricate sub-arcsecond-level optical substrates through mechanical polishing or double-sided polishing, the yield of these technologies for fabricating sub-arcsecond-level graded substrates is not high due to limitations in the processing mechanism, polishing stress, and controllability, resulting in high production costs. This is especially true for the fabrication of large-size optical substrates, where the processing is even more difficult to control and yields are even lower. Furthermore, existing technologies also fabricate sub-arcsecond-level graded substrates through processes such as magnetron sputtering, chemical vapor deposition, spin coating, or photolithography. However, limitations in the distribution of the deposition source, the spin coating flow field, or mask design lead to insufficient control over the thickness gradient and uniformity of the sub-arcsecond-level graded substrates. This makes it difficult to guarantee gradient accuracy and thickness uniformity, resulting in uneven surface distribution of the fabricated substrates and causing problems such as insufficient diffraction efficiency or image quality distortion. Summary of the Invention

[0004] This application addresses the shortcomings of existing methods by proposing a method and apparatus for preparing sub-arcsecond graded substrates by ion beam etching, thereby solving at least one technical problem in related technologies, such as low yield, insufficient continuity accuracy, or poor uniformity in the preparation of sub-arcsecond graded substrates.

[0005] Firstly, This application provides a method for preparing sub-arcsecond graded substrates by ion beam etching, including the following steps: To confirm the relationship between dwell time and etching depth during ion beam etching of the substrate, a first model was established; Based on the processing target of the substrate, the etching amount distribution of the substrate along the etching path of the ion beam is confirmed; The relationship between the velocity and acceleration of the ion beam and time was confirmed when the ion beam etched along the etching path to form a second model; Based on the etching amount distribution and the first model, the residence time distribution is confirmed; Based on the dwell time distribution and the second model, the velocity and acceleration distributions of ion beam etching along the time are confirmed. The ion beam is controlled to etch the etching path according to the velocity and acceleration distribution.

[0006] Specifically, the main technical concept of this application lies in controlling the dwell time of the ion beam on the etching path by controlling the velocity and acceleration distribution during ion beam etching. This dwell time allows for the acquisition of the etching depth of the target, i.e., the etching amount distribution, which is the target being processed, thus achieving the processing of sub-arcsecond graded substrates. Because this application uses a continuously moving ion beam for substrate etching, non-contact processing can be achieved, the process is controllable, and it has good reliability. Furthermore, this application only regulates the velocity and acceleration of the ion beam etching, resulting in fewer control variables and a continuous processing flow, ensuring good continuity of the final sub-arcsecond graded substrate. Based on the stability and processing continuity of ion beam etching, this application is easy to reproduce, improving the yield of sub-arcsecond graded substrates.

[0007] Furthermore, the method for preparing sub-arcsecond graded substrates by ion beam etching provided in this application also includes: Obtain the film thickness distribution along the etching path; Based on the film thickness distribution and the etching amount distribution, the correction parameters of the first model are confirmed.

[0008] Specifically, another technical concept of this application lies in compensating for the surface flatness of the substrate by modifying parameters, thereby improving the reliability of sub-arcsecond gradient substrates processed by ion beam etching. It is worth explaining that although the processing target has very practical guiding significance, considering the errors present in actual etching and the overall size requirements of the substrate, both over-etching and under-etching of the substrate will affect its final use. Therefore, this application provides processing compensation for the substrate through modifying parameters. Simultaneously, this application defines the modifying parameter as the sacrifice height of the shallowest point among all etching points along the etching path, used to provide processing compensation for ion beam etching according to velocity and acceleration distributions, thereby improving processing reliability.

[0009] Furthermore, based on the velocity distribution and acceleration distribution, the minimum and maximum velocities, as well as the minimum and maximum accelerations of the ion beam, are determined respectively. When the maximum speed is greater than a first speed threshold or when the maximum acceleration is greater than a first acceleration threshold, or when the minimum speed is less than a second speed threshold or when the minimum acceleration is less than a second acceleration threshold, the etching of the etching path is performed in at least two steps.

[0010] Specifically, another technical concept of this application is to control the maximum value of speed or acceleration through a first speed threshold and a first acceleration threshold. This avoids excessive jitter in the ion beam due to limitations in the mechanical structure of the equipment, which could lead to increased substrate waviness. It also prevents the increase in speed and acceleration from exceeding the equipment's control limits, thus avoiding a decrease in processing accuracy due to the inability to achieve the expected speed and acceleration. Simultaneously, this application also controls the minimum value of speed and acceleration through a second speed threshold and a second acceleration threshold. This avoids excessively long dwell times caused by insufficient speed or acceleration, which could distort the relationship between the etching depth and dwell time of the first model and lead to a decrease in processing accuracy. Therefore, this application, through multiple scans, ensures that both the maximum and minimum values ​​of speed and acceleration are within a controllable range, thereby ensuring processing reliability and improving substrate processing yield.

[0011] Furthermore, the method for preparing sub-arcsecond graded substrates by ion beam etching provided in this application also includes: The number of etching operations is determined based on the correction threshold and the correction parameters. The correction parameter and the time are divided equally according to the number of etchings to confirm the current correction parameter and the current time; Based on the current correction parameters and the current time, confirm the current time distribution and the current acceleration distribution.

[0012] Specifically, another technical concept of this application lies in determining the number of etching passes by adjusting parameters, thereby achieving multiple etching passes along the etching path under safe etching conditions and ensuring the reliability of ion beam etching. It is worth explaining that the adjustment threshold refers to the minimum acceptable processing allowance during a single ion beam etching operation. That is, when the adjustment parameters are less than the adjustment threshold, the substrate is highly likely to experience "over-etching." Therefore, the number of etching passes determined by the adjustment threshold and adjustment parameters in this application can balance the maximum and minimum values ​​of velocity and acceleration during ion beam etching, while also ensuring processing reliability.

[0013] Furthermore, after performing an etching operation based on the current time distribution and the current acceleration distribution, the film thickness distribution is obtained again to optimize the current correction parameters.

[0014] In some possible embodiments, a sample of the substrate is etched by an ion beam before etching the substrate; The first model is optimized based on the sample time and sample depth of single-point etching of the sample.

[0015] Specifically, another technical concept of this application is to use the actual etching of the sample to correct the first model, thereby improving the reliability of the first model, that is, improving the reliability of the relationship between residence time and etching depth, and thus improving the processing reliability.

[0016] In some possible implementations, the processing target includes either a linearly or non-linearly distributed etching amount.

[0017] Secondly, This application provides an electronic device including a memory, a processor, and a computer program stored in the memory. The processor executes the computer program to implement the method for preparing sub-arcsecond graded substrates by ion beam etching provided in any possible embodiment of the first aspect. It is worth noting that the beneficial effects provided by any embodiment of the second aspect can be understood in conjunction with the effective effects provided by any embodiment of the first aspect.

[0018] Thirdly, This application provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the method for preparing sub-arcsecond graded substrates by ion beam etching provided in any possible embodiment of the first aspect. The beneficial effects provided by any embodiment of the third aspect can be understood with reference to the effective effects provided by any embodiment of the first aspect.

[0019] Fourthly, This application provides a computer program product, including a computer program that, when executed by a processor, implements the method for preparing sub-arcsecond graded substrates by ion beam etching provided in any possible embodiment of the first aspect. The beneficial effects provided by any embodiment of the fourth aspect can be understood with reference to the effective effects provided by any embodiment of the first aspect.

[0020] The beneficial technical effects of the technical solutions provided in this application include: By using velocity and acceleration distributions, this application can obtain the residence time distribution of the ion beam along the etching path based on the second model. That is, this application controls the residence time of the ion beam along the etching path by adjusting the ion beam velocity and acceleration. Simultaneously, the residence time distribution is confirmed based on the first model and the etching amount distribution. The first model defines the relationship between residence time and etching depth. This application can control the residence time of the ion beam along the etching path by adjusting the ion beam velocity and acceleration to obtain the corresponding residence time distribution. In other words, this application can control the etching amount distribution along the etching path by adjusting the ion beam velocity and acceleration, thus enabling the processing of gradient substrates. Furthermore, the technical solution provided by this application is based on ion beam etching technology. Due to the advantages of non-contact and atomic-level processing, this application can achieve sub-arcsecond-level gradient substrate processing. Because the subarcsecond-level graded substrate is fabricated using a continuously moving ion beam, with only the speed and acceleration of the ion beam being controlled, the subarcsecond-level graded substrate prepared in this application exhibits good continuity. Furthermore, since the fabrication target is based on a first model, and the residence time and etching depth in the first model are summable and describable, this application demonstrates good fabrication accuracy. Therefore, this application can improve the continuity, fabrication accuracy, and yield of subarcsecond-level graded substrates.

[0021] Additional aspects and advantages of this application will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of this application. Attached Figure Description

[0022] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 A schematic flowchart illustrating a method for preparing subarcsecond-level graded substrates by ion beam etching, provided as an embodiment of this application; Figure 2 This is a schematic diagram illustrating the fabrication of a subarcsecond graded substrate by ion beam etching according to another embodiment of this application. Figure 3 This is a schematic diagram of the structure of a linear variable optical filter provided in an embodiment of this application; Figure 4 This application provides a schematic diagram showing the relationship between etching path and time, the relationship between velocity and time, and the relationship between acceleration and time, according to an embodiment of the present application. Figure 5 For the base film Figure 4 A schematic diagram of the structure of a subarcsecond-level gradient substrate obtained by processing medium velocity distribution and acceleration distribution; Figure 6 This is a schematic diagram of the structure of an electronic device provided in one embodiment; Figure 7 This is a schematic diagram of the structure of a device provided in one embodiment. Detailed Implementation The embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the embodiments described below with reference to the accompanying drawings are exemplary descriptions for explaining the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions of the embodiments of this application.

[0023] Those skilled in the art will understand that, unless specifically stated otherwise, the terms "described" and "the" as used herein may also include plural forms. It should be further understood that the term "comprising" as used in the specification of this application means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude other features, information, data, steps, operations, elements, components, and / or combinations thereof supported by this art. The term "and / or" as used herein refers to at least one of the items defined by the term; for example, "A and / or B" can be implemented as "A," or as "B," or as "A and B."

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0025] This application mainly relates to a method and equipment for preparing sub-arcsecond graded substrates by ion beam etching. It mainly uses ion beam etching technology in conjunction with a first model and a second model to generate velocity distribution and acceleration distribution, and uses the velocity distribution and acceleration distribution as processing formula to process sub-arcsecond graded substrates, thereby improving processing accuracy and processing reliability.

[0026] The research and development approach of this application includes: establishing a first model based on the relationship between dwell time and etching depth; that is, using the first model, etching depth can be predicted through dwell time, or dwell time can be predicted through etching depth. Therefore, this application can determine the etching amount distribution along the etching path of the ion beam based on the processing target, i.e., the sub-arcsecond graded substrate to be prepared and the surface to be processed before etching (the etching amount distribution is obtained by subtracting the processing target from the surface to be processed). Given the etching amount distribution, the dwell time distribution can be predicted based on the first model. Therefore, this application can establish a second model based on the relationship between velocity and acceleration and time. This second model can characterize the relationship between dwell time and velocity and acceleration. In other words, the velocity distribution and acceleration distribution can be predicted through the dwell time distribution, and the etching amount distribution can be predicted through the velocity distribution and acceleration distribution. Thus, this application can control the dwell time distribution on the substrate etching path through the velocity distribution and acceleration distribution, thereby obtaining the expected etching amount distribution, i.e., the processing target, and achieving high-precision and reliable processing of sub-arcsecond graded substrates.

[0027] The technical solution of this application and how it solves the above-mentioned technical problems are described in detail below with specific embodiments. It should be noted that the following embodiments can be referenced, borrowed, or combined with each other, and the same terms, similar features, and similar implementation steps in different embodiments will not be described again.

[0028] Alternatively, please refer to Figure 1 This is a schematic flowchart illustrating a method for preparing subarcsecond-level gradient substrates by ion beam etching, as provided in an embodiment of this application.

[0029] Specifically, ion beam etching (IBE) is an advanced micro-nano manufacturing technology that uses a high-energy ion beam to remove material surfaces and achieve substrate surface processing. Subarcsecond-level gradient substrates refer to substrates with gradient structures at subarcsecond precision. Therefore, the purpose of this application is to provide an ion beam etching method for processing subarcsecond-level gradient structure substrates. It is understood that gradient structures can be categorized into linear and nonlinear relationships based on the gradient relationship. Linear relationships include those characterized by slope. The slope represents the inclination of a straight line on a plane about a coordinate axis, while nonlinear relationships refer to relationships that cannot be represented by slope on a plane. In other words, the significance of this application lies in processing gradient structures within a processing range of processing angles greater than 0.1″ and less than 1″.

[0030] Optionally, this application uses the relationship between dwell time and etching depth when etching a substrate with an ion beam to form a first model.

[0031] For example, in ion beam etching, if the redeposition effect is not considered, the etching depth and dwell time have the following relationship: ; This refers to the etching depth. This refers to sputtering output. This refers to beam current density. This refers to the length of stay. This refers to the atomic density of the substrate. That is, without considering the redeposition effect, the etching depth and dwell time have a linear relationship. However, as the redeposition effect significantly increases, the etching rate gradually decreases with increasing dwell time and etching depth. In this case, a correction model can be introduced to adjust the above linear relationship, thereby establishing a corresponding model, for example: ; This refers to the initial etching rate, i.e. , This refers to the redeposition attenuation coefficient. The model described above characterizes the linear relationship in ion beam etching initially; as dwell time increases, the redeposition ratio rises, the etching rate decreases, and the etching depth also slows down. In other words, the first model provided in this application is a mathematical model established based on dwell time and etching depth, used to characterize the relationship between dwell time and etching depth. It is worth noting that any model capable of characterizing the relationship between dwell time and etching depth can be used in this application to establish the first model.

[0032] Optionally, based on the first model, this application determines the etching amount distribution of the substrate along the etching path of the ion beam according to the processing objectives of the substrate.

[0033] It is worth explaining that the processing target refers to the gradient structure of the subarcsecond-level gradient substrate to be prepared. Therefore, given the current appearance of the substrate and the processing target, the etching amount distribution of the ion beam along the etching path can be obtained by subtracting the processing target from the current surface flatness of the substrate.

[0034] For example: Given that the height of a point in the coordinate system is 0, and you want to etch it to -100nm, then the etching depth of that point is... This allows for the calculation of the etching depth at all points along the etching path, meaning that the etching amount distribution can be formed by combining the etching depths at all points along the etching path.

[0035] Optionally, given the known etching amount distribution, the relationship between the velocity and acceleration of the ion beam and time is determined when the ion beam etches along the etching path, in order to form a second model.

[0036] For example: Assuming the ion source scans along the etching path with a constant acceleration, the residence time distribution along the etching path satisfies: ; This refers to the initial velocity. This refers to the starting point of the etching path, which characterizes the relationship between residence time and velocity and acceleration under the second model. It is worth noting that any model that can characterize the time distribution using velocity and acceleration can be used as the second model in this application.

[0037] Optionally, the residence time distribution can be determined based on the etching amount distribution and the first model.

[0038] For example, still taking a linear relationship as an example, the relationship between the residence time distribution and the etching path is as follows: ; This refers to the correction parameters (which can be omitted under ideal machining conditions). This refers to the linear slope. Under a linear relationship, the etching amount distribution along the etching path can be obtained through the slope, and thus the etching amount distribution can characterize the residence time distribution along the etching path. In fact, the etching amount distribution at each point along the etching path is known, meaning the etching depth at each point is known. Given the known etching depth at each point, the residence time required to process the corresponding etching depth at each point can be calculated based on the first model. Therefore, the residence time at each point can be calculated, and the residence time distribution is formed by the combination of residence times at each point. It is worth explaining that nonlinear relationships can be understood in the same way as linear relationships. constant, Replace with a non-linear formula.

[0039] Optionally, based on the residence time distribution and the second model, the velocity distribution and acceleration distribution of ion beam etching along time are confirmed.

[0040] For example: still using and linear relationship For example, given the residence time distribution, we can solve the problem by simultaneously solving the residence time distribution and the second model. We can obtain: The velocity distribution is as follows: ; acceleration distribution is ; Thus, the velocity and acceleration distributions were obtained. It is worth noting that the first and second models, represented by other mathematical formulas, can also be solved using the above transformation process for nonlinear processing targets.

[0041] Optionally, given the known velocity and acceleration distributions, the ion beam can be controlled to etch the etching path based on these distributions. That is, when the ion beam etching equipment controls the ion beam along the etching path using the velocity and acceleration distributions obtained above, the residence time distribution of the ion beam along the etching path can be determined according to the etching amount distribution. Since the residence time and etching depth have been defined by the first model, the etching amount distribution is also determined when the residence time distribution is determined, thus achieving the processing objective of this application.

[0042] Optionally, the velocity and acceleration distribution can be achieved by the movement of the processing stage of the ion beam etching equipment. That is, the substrate is fixed to the processing stage, and the processing stage drives the substrate to move, thereby realizing the velocity and acceleration distribution of the ion beam etching. The processing stage of the ion beam etching equipment can be understood with reference to the technical solutions provided by the prior art.

[0043] Alternatively, please refer to Figure 2 This is a schematic diagram illustrating the fabrication of a subarcsecond-level gradient substrate by ion beam etching, according to another embodiment of this application.

[0044] Specifically, in the actual processing, the workflow of this application is as follows: Before etching the substrate, a sample of the substrate is first etched using an ion beam. Then, based on the sample time and depth of the single-point etched sample, the first model is optimized. Although this application establishes the first model based on the material properties of the substrate, the first model may deviate due to the influence of equipment operating conditions, the actual state of the material, etc. Therefore, this application performs real-time etching on the sample before processing, and optimizes the first model with the actual etching depth and residence time. This ensures that the etching depth and residence time of the current substrate during the etching process are basically completely consistent with the actual processing, thereby improving the processing accuracy of sub-arcsecond graded substrates.

[0045] Optionally, the test of the specimen can be performed multiple times and fitted.

[0046] Optionally, the film thickness distribution along the etching path can be obtained before etching the substrate. Substrate processing typically allows for a certain machining allowance to avoid over-etching, which could result in the substrate thickness failing to meet usage requirements.

[0047] Optionally, after measuring the film thickness distribution before substrate processing, the correction parameters for the first model can be determined based on the film thickness distribution and etching amount distribution, i.e., the formula. The correction parameters mentioned in It is understandable that the etching depth distribution refers to the distribution along the etching path under a perfectly ideal situation with no machining allowance. In reality, considering the controllability limits of the machining stage, such as at the point of minimum etching depth, which theoretically approaches 0, the speed and acceleration of ion beam etching approach infinity, making it difficult for mechanical structures to provide such speed and acceleration. Therefore, the correction parameters... It provides machining allowance, avoiding the problem that the minimum etching depth cannot be achieved mechanically, and also avoiding the "over-etching" problem of the ion beam. It is worth understanding that the correction parameter refers to the thickness value corresponding to the point with the minimum machining allowance on the etching path.

[0048] For example, based on the accuracy requirements of the final thickness of the substrate, the machining allowance at any point on the etching path can be obtained by subtracting the final thickness from the current thickness of the substrate. The minimum value among all machining allowances is used as a correction parameter to correct the first model, thereby ensuring that the final thickness meets the accuracy requirements of the substrate, avoiding the "over-etching" problem, and improving the reliability of this application.

[0049] Optionally, the number of etching cycles of the ion beam under the current correction parameters can be determined by adjusting the threshold.

[0050] Optionally, the value range of the correction threshold is 40nm-60nm.

[0051] Optionally, if the correction parameters cannot be split, the ion beam can be used to etch the etching path based on the processing target, the velocity distribution obtained from the first model, and the second model. That is, after completing this processing step, the remaining etching steps are 0, allowing the substrate's etching amount distribution to be checked after processing to ensure it meets the expected processing target. For example, if the correction parameter is 70nm, splitting it into 35nm will not meet the correction threshold requirement, necessitating another etching step.

[0052] Optionally, if the correction parameters can be split, the number of etching operations can be determined based on the correction threshold and the correction parameters. For example, if the correction parameter is 150nm and the correction threshold is 40nm, it can be split into 3 operations; if the correction threshold is 60nm, it can be split into 2 operations. Other splitting operations can be understood by referring to the above examples.

[0053] Optionally, if the number of etching operations can be split according to the correction parameters, the correction parameters and dwell time are evenly divided, so that the first velocity distribution and the first acceleration distribution are re-obtained through the first model and the second model. Then, the first processing is performed through the first velocity distribution and the first acceleration distribution, and the second processing is performed through the second velocity distribution and the second acceleration distribution, and so on, until the remaining number of processing operations is 0, and then the etching ends.

[0054] Optionally, after completing another processing step, the film thickness distribution is re-acquired, and the current correction parameters are optimized. For example, if the correction parameter is 162nm and the correction threshold is 50nm, then the etching process involves 3 etching passes. The correction parameter for the first etching pass is 54nm, and the etching path is processed based on the first velocity distribution and the first acceleration distribution obtained at 54nm. After the first processing, the correction parameter is re-measured, for example, to 106nm. Therefore, the correction parameter for the second etching pass is 53nm, and the etching path is processed based on the second velocity distribution and the second acceleration distribution obtained at 53nm. This process continues. By optimizing the correction parameters in real time, each etching pass in multi-etching scenarios can have a reasonable processing margin, ensuring processing reliability.

[0055] Alternatively, please refer to Figure 3 This is a schematic diagram of the structure of a linear variable optical filter provided in an embodiment of this application.

[0056] Specifically, a linear variable optical filter (LVOF or LVF) is an interferometric filter whose spectral characteristics change linearly and continuously along the spatial direction. It achieves monotonic variation of the center wavelength or bandpass / cutoff wavelength with position through a wedge-shaped multilayer thin-film structure, thus providing a one-to-one "position-wavelength" tuning function on a single filter. The linear variable optical filter consists of a wedge-shaped cavity 1 and dielectric films 2 stacked on the surface of the wedge-shaped cavity. The wedge-shaped cavity 1 has a gradient structure. It is worth understanding that... Figure 3 For ease of illustration, the slope of wedge cavity 1 has been exaggerated; in reality, the included angle corresponding to the slope of wedge cavity 1 is between 0.1″ and 1″. The method for preparing sub-arcsecond graded substrates by ion beam etching provided in this application is mainly used to realize the fabrication of wedge cavity 1.

[0057] Optionally, with Figure 3 Taking the wedge-shaped cavity 1, which gradually deepens from left to right, as an example, the processing objective of this application is to create a wedge-shaped surface with progressively increasing etching depth from left to right. That is, before processing, the substrate is a pre-treated flat surface or a sloped surface similar to the wedge-shaped surface. Taking a flat surface as an example, the processing objective of this application is to etch the material between the flat surface and the wedge-shaped surface to obtain the wedge-shaped surface structure of the wedge-shaped cavity 1. Specifically, taking the leftmost side of the wedge-shaped cavity 1 as the starting point and the rightmost side as the ending point, the etching path is the path between the starting point and the ending point, and the thickness difference of the material between the flat surface and the wedge-shaped surface is the etching amount distribution.

[0058] Optionally, the angle β between the wedge-shaped surface of the wedge cavity 1 and the horizontal axis is the processing range of this application—sub-arcsecond level, i.e., 0.1″ < β < 1″. It can be understood that an arcsecond, also known as an arc-second, with the symbol "″", is a unit for measuring plane angles, defined as one-sixtieth of an arcminute, where 1 degree equals 60 arcminutes or 3600 arcseconds.

[0059] Alternatively, please refer to Figure 4 This application provides a schematic diagram showing the relationship between etching path and time, the relationship between velocity and time, and the relationship between acceleration and time, according to an embodiment of the present application.

[0060] Specifically, still in Figure 3 The wedge-shaped surface of the wedge cavity 1 shown is the processing target. Since the wedge surface has a gradually deepening structure from left to right, and the substrate before processing is generally a flat surface, the etching amount distribution between the surface to be processed on the substrate and the wedge-shaped surface of the processing target ranges from shallow to deep. That is, according to the first model, the residence time distribution along the etching path increases from left to right. For ease of illustration of the velocity and acceleration distributions, the right side of the wedge cavity 1 is taken as the starting point of the etching path, and the left side as the ending point. Figure 4 The leftmost diagram shows the residence time distribution, gradually increasing from the shortest residence time at the beginning to the longest residence time at the end. Furthermore, given the residence time distribution, the velocity and acceleration distributions of the ion beam can be calculated using the second model. Figure 4 The diagram in the middle shows the velocity distribution; the ion beam's movement gradually increases from the minimum velocity at the starting point to the maximum velocity at the end point. Figure 4 The rightmost diagram shows the acceleration distribution, where the ion beam's acceleration gradually increases from a minimum at the starting point to a maximum at the endpoint. This means that the velocity and acceleration of the ion beam exhibit a defined temporal distribution relationship along the etching path from the starting point to the endpoint. Based on this temporal distribution, the residence time distribution of the ion beam along the etching path can be determined.

[0061] Optionally, this application further determines the minimum and maximum velocities, as well as the minimum and maximum accelerations of the ion beam, based on the velocity distribution and acceleration distribution, respectively; when the maximum velocity is greater than a first velocity threshold or when the maximum acceleration is greater than a first acceleration threshold, or when the minimum velocity is less than a second velocity threshold or when the minimum acceleration is less than a second acceleration threshold, the etching of the etching path is performed in at least two steps to improve the reliability of the first model and reduce interference from the equipment itself.

[0062] It is worth understanding that, according to Figure 4It is known that the lower the velocity and acceleration, the longer the dwell time. Furthermore, according to the explanation of the first model mentioned above, the atomic redeposition effect is weak initially, and the etching depth of ion beam etching can be considered linearly related to the dwell time initially. As the dwell time increases, the redeposition effect accumulates, and the etching rate gradually decreases; that is, the etching depth, initially linearly related, tends to level off with increasing dwell time. Therefore, an excessively long dwell time will increase the risk of deviation from the expected etching depth or make model prediction more difficult. Thus, a reasonably set maximum dwell time helps improve the prediction accuracy of the first model, and a reasonably set maximum dwell time can improve the processing accuracy of sub-arcsecond graded substrates processed using this application. Therefore, setting the second velocity threshold and the second acceleration threshold helps improve the reliability of this application. Simultaneously, the lower the velocity and acceleration, the shorter the dwell time. Since the etching depth is basically linearly related to the dwell time at this point, the first model's prediction of etching depth based on dwell time is more accurate. However, a shorter dwell time is not always better. As the dwell time decreases, the speed and acceleration of the ion beam increase. This leads to more pronounced vibrations in the mechanical equipment during the control of the ion beam etching speed and acceleration, resulting in significant waviness in the ion-etched gradient structure and affecting device performance. Therefore, this application improves the stability of the ion beam movement by setting a first speed threshold and a first acceleration threshold, thereby reducing the waviness of the gradient structure and improving the processing quality of sub-arcsecond gradient substrates. Specifically, the ion beam etching speed and acceleration in this application must be limited to between the first speed threshold and the second speed threshold, and between the first acceleration threshold and the second acceleration threshold, respectively. In practice, the first speed threshold is greater than the second speed threshold, and the first acceleration threshold is greater than the second acceleration threshold.

[0063] Optionally, based on the velocity and acceleration distributions, multiple etching processes can be used to ensure machining accuracy and reliability.

[0064] Optionally, machining allowances can be reserved based on the velocity and acceleration distributions so that the correction parameters confirmed based on the machining allowances can be broken down into the number of etching operations when the velocity and acceleration distributions meet the threshold limits.

[0065] Optionally, this application employs a reciprocating etching method to achieve multiple etching processes. It is worth explaining that... Figure 4 This provides the residence time, velocity, and acceleration distributions as the etching depth gradually decreases from left to right along the etching path. To achieve reciprocating etching, the corresponding... Figure 4 The curves in the diagrams are all mirror images, meaning the residence time distribution in the leftmost diagram decreases from largest to smallest, while the residence time distribution in the middle diagram decreases from largest to smallest, and the residence time distribution in the rightmost diagram also decreases from largest to smallest. In fact, during the etching cycle decomposition process, using... Figure 4Taking the leftmost 700s as an example, splitting it twice halves the maximum dwell time to 350s, obtaining a new dwell time distribution, and thus obtaining a new velocity and acceleration distribution. Similarly, splitting it three times results in 700 / 3s. The distribution diagram for the first etching in the reciprocating etching process is as follows... Figure 4 As shown, the second etching is exactly the opposite.

[0066] Alternatively, please refer to Figure 5 For the base film Figure 4 A schematic diagram of the structure of a subarcsecond-level gradient substrate obtained by processing medium velocity distribution and acceleration distribution.

[0067] Specifically, taking a 200mm substrate as an example, the etching path starts at -100mm and ends at 100mm. On this substrate, this application can achieve a gradient structure with a depth from -60nm to -100nm. That is, a gradient structure can be achieved within a depth of 40nm on a 200mm substrate. The slope is 40nm / 200mm = 2·10. -7 Converted to angles, this is approximately 0.115 × 10⁻⁶. -6 °, or 0.024″. This means that this application can achieve sub-arcsecond-level gradient substrate processing. It is worth explaining that the above precision is not achieved in a single etching operation, but rather represents the theoretical limit of precision achieved in this application. Due to limitations imposed by the ion source driving structure, the speed and acceleration cannot be infinitely small, making it difficult to remove the rightmost etched portion of the gradient structure in a single processing step. Since the rightmost etched portion is extremely small, meaning the dwell time is extremely short, the ion beam speed and acceleration are extremely high. Existing ion beam etching equipment stages cannot achieve precise and stable control of speeds and minimum and maximum accelerations across multiple orders of magnitude, making it difficult to achieve sub-arcsecond-level precision in a single processing step. Therefore, this application reduces the maximum values ​​of speed and acceleration through multiple etching operations, keeping them within a threshold control range. This allows the stage to precisely control the speed and acceleration distribution of the ion beam etching, enabling the separation of each gradient layer. This allows the application to improve processing precision through multiple scanning etching stacking. Figure 5 This represents the theoretical limit of precision in this application. However, the multiple scanning etching method will lead to a continuous increase in the correction parameters, requiring a significant sacrifice of machining allowance and resulting in increased processing costs. Therefore, although the theoretical limit of this application can reach 0.024″, considering product yield and production costs, this application has high practicality in sub-nanometer graded substrate processing.

[0068] Optionally, this application can control the wedge angle of the front and rear surfaces to 0.8″ on a fused silica window with a diameter of 200mm by controlling the velocity distribution and acceleration distribution, for use in ultra-high power laser systems.

[0069] Optionally, this application can use a linear function to control the film thickness gradient on a 200mm diameter optical wafer to achieve a continuous film thickness change from the edge to the edge on the diagonal of the diameter, for phase compensation in optical communication systems.

[0070] Optionally, this application can optimize the diffraction efficiency at different positions in the near-eye display system and the nanoimprint master for the near-eye display system by nonlinear gradient etching, thereby obtaining a uniform coupling-in and coupling-out energy distribution and achieving uniform emitted brightness.

[0071] Optionally, this application can suppress zero-order diffraction in holographic optical elements by controlling the film thickness with gradient, thereby improving image contrast and clarity.

[0072] Optionally, this application can employ a reciprocating scanning strategy during the preparation of the optical detection reference sheet to reduce surface waviness, thereby obtaining high flatness and a stable gradient film thickness distribution for interferometer calibration.

[0073] Optionally, this disclosure provides an electronic device including a memory, a processor, and a computer program stored in the memory. The processor executes the computer program to implement the steps of the method provided in any optional embodiment of this disclosure. Compared with the prior art, this can improve the continuity, processing accuracy, and yield of sub-arcsecond graded substrates. In one alternative embodiment, an electronic device is provided; please refer to Figure 6 A schematic diagram of an electronic device provided in one embodiment includes a processor 100 and a memory 200. The processor 100 and the memory 200 are connected, for example, via a bus 300. Optionally, the electronic device may further include a transceiver, which can be used for data interaction between the electronic device and other electronic devices, such as sending and / or receiving data. It should be noted that in practical applications, the transceiver is not limited to one unit, and the structure of this electronic device does not constitute a limitation on the embodiments of this disclosure.

[0074] Processor 100 may be a CPU (Central Processing Unit), a general-purpose processor, a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It may implement or execute the various exemplary logic blocks, modules, and circuits described in conjunction with this disclosure. Processor 100 may also be a combination that implements computational functions, such as including one or more microprocessor combinations, a combination of a DSP and a microprocessor, etc.

[0075] The memory 200 may be ROM (Read Only Memory) or other types of static storage devices capable of storing static information and instructions, RAM (Random Access Memory) or other types of dynamic storage devices capable of storing information and instructions, or EEPROM (Electrically Erasable Programmable Read Only Memory), CD-ROM (Compact Disc Read Only Memory) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media, other magnetic storage devices, or any other medium capable of carrying or storing computer programs and capable of being read by a computer, without limitation herein.

[0076] The memory 200 is used to store computer programs that execute embodiments of the present disclosure, and the execution is controlled by the processor 100. The processor 100 is used to execute the computer programs stored in the memory 200 to implement the steps shown in the foregoing method embodiments.

[0077] Bus 300 may include a pathway for transmitting information between the aforementioned components. Bus 300 may be a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. Bus 300 can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 6 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0078] Electronic equipment includes, but is not limited to, industrial control computers and industrial control PCs.

[0079] This disclosure provides a computer-readable storage medium storing a computer program, which, when executed by a processor, can implement the steps and corresponding content of the aforementioned method embodiments.

[0080] This disclosure also provides a computer program product, including a computer program that, when executed by a processor, can implement the steps and corresponding content of the aforementioned method embodiments.

[0081] Optionally, Figure 7 This is a schematic diagram of the structure of a device provided in one embodiment.

[0082] Specifically, the apparatus provided in this application includes a detection module 400, an execution module 500, and an ion source module 600. The detection module 400 is used to acquire the film thickness distribution along the etching path, and to acquire the sample time and depth of the sample before etching the substrate. The execution module 500 is used to calculate and acquire the velocity distribution and acceleration distribution based on the film thickness distribution, sample time, and sample depth acquired by the detection module 400, as well as the first and second models established within it, thereby controlling the ion source module 600 to process the substrate using the velocity and acceleration distributions. It is understood that this application also includes structures commonly used in substrate processing, such as multi-axis motion stages and vacuum chambers.

[0083] Optionally, the detection module 400 includes an interferometer or a film thickness gauge.

[0084] Optionally, the first module and the second model can be obtained through training and validation sets. The training set refers to a dataset that includes multiple processing target samples and multiple processing result samples corresponding to the multiple processing target samples, and the validation set refers to a dataset that includes target structure samples corresponding to the multiple processing target samples. This application obtains the optimized first model and the second model through multiple training sessions on the training set and the validation set, thereby improving the ion beam etching accuracy of this application.

[0085] In summary, this application provides a method for fabricating sub-arcsecond graded substrates via ion beam etching, comprising: establishing a first model of dwell time and etching depth; determining the etching amount distribution along the etching path based on the processing target; and thus, obtaining the dwell time distribution along the etching path based on the first model. The dwell time can be characterized by a velocity and acceleration versus time model established by a second model. Substituting the dwell time distribution into the second model, the velocity and acceleration distributions of the ion beam can be solved. This application can obtain the corresponding dwell time distribution by running the ion beam according to the velocity and acceleration distributions, and then obtain the corresponding etching amount distribution through the dwell time distribution, thereby achieving the processing target. Since the above process is based on the first and second models, this application can theoretically be used for processing graded structures of any linear or nonlinear processing target. Furthermore, since this application uses ion beam etching technology, it can manipulate atomic-level targets, meaning this application can reliably process sub-arcsecond graded substrates. Because the first and second models can be accurately modeled, this application also has very high processing accuracy.

[0086] Those skilled in the art will understand that the steps, measures, and solutions in the various operations, methods, and processes discussed in this application can be alternated, modified, combined, or deleted. Furthermore, other steps, measures, and solutions in the various operations, methods, and processes discussed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted. Furthermore, steps, measures, and solutions in related technologies that are similar to those disclosed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted.

[0087] In the description of this application, the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate directions or positional relationships based on the exemplary directions or positional relationships shown in the accompanying drawings. They are used to facilitate the description or simplification of the embodiments of this application and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0088] 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. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0089] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0090] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0091] The above description is only a partial embodiment of this application. It should be noted that for those skilled in the art, other similar implementation methods based on the technical concept of this application, without departing from the technical concept of this application, also fall within the protection scope of the embodiments of this application.

Claims

1. A method for fabricating a sub-arcsecond graded substrate by ion beam etching, characterized in that, The method comprises the following steps: confirming a relationship between dwell time and etching depth when etching a substrate by an ion beam to form a first model; confirming an etching amount distribution of the substrate along an etching path of the ion beam according to a processing target of the substrate; confirming a relationship between velocity and acceleration of the ion beam along the etching path with respect to time when etching by the ion beam along the etching path to form a second model; confirming a dwell time distribution according to the etching amount distribution and the first model; confirming a velocity distribution and an acceleration distribution of the ion beam along the time according to the dwell time distribution and the second model; controlling the ion beam to etch the etching path according to the velocity distribution and the acceleration distribution.

2. The method of claim 1, wherein the ion beam etching is performed by using a beam current of 0.1 mA or less. Further comprising: obtaining a film thickness distribution of the etching path; confirming a correction parameter of the first model according to the film thickness distribution and the etching amount distribution.

3. The method of claim 2, wherein the ion beam is a pulsed ion beam. confirming a minimum velocity and a maximum velocity and a minimum acceleration and a maximum acceleration of the ion beam according to the velocity distribution and the acceleration distribution respectively; when the maximum velocity is greater than a first velocity threshold or when the maximum acceleration is greater than a first acceleration threshold, or when the minimum velocity is less than a second velocity threshold or when the minimum acceleration is less than a second acceleration threshold, etching the etching path is divided into at least two times.

4. The method of claim 3, wherein the ion beam is a pulsed ion beam. Further comprising: confirming an etching time according to a correction threshold and the correction parameter; dividing the correction parameter and the time according to the etching time respectively to confirm a current correction parameter and a current time; confirming a current dwell time distribution and a current acceleration distribution according to the current correction parameter and the current time.

5. The method of claim 4, wherein the ion beam is a pulsed ion beam. After performing etching once by the current dwell time distribution and the current acceleration distribution, the film thickness distribution is obtained again to optimize the current correction parameter.

6. The method of claim 1, wherein the ion beam etching is performed by using a beam current of 0.1 mA or less, a beam voltage of 10 kV or more, and a beam diameter of 0.1 mm or less. Before etching the substrate, etching a sample member of the substrate by an ion beam; optimizing the first model according to a sample time and a sample depth of etching the sample member of the sample member.

7. The method of claim 1, wherein the ion beam etching is performed by using a beam current of 0.1 mA or less, a beam voltage of 10 kV or more, and a beam diameter of 0.1 mm or less. The processing target comprises any one of linear or non-linear distribution of etching amount.

8. An electronic device comprising a memory, a processor, and a computer program stored on the memory, wherein the computer program, when executed by the processor, is arranged to perform the method of any one of claims 1 to 7. The processor executes the computer program to implement the method of claim 1-7 for preparing a sub-angström gradual change substrate by etching with an ion beam.

9. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the method of claim 1-7 for preparing a sub-angström gradual change substrate by etching with an ion beam.

10. A computer program product comprising a computer program, characterized in that, The computer program is executed by the processor to implement the method of claim 1-7 for preparing a sub-angström gradual change substrate by etching with an ion beam.

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