Method for manufacturing gray scale pattern on wafer

Abstract

The invention relates to a method for manufacturing a gray scale pattern on a wafer, which is characterized in that black and white lines or square frames with different widths or sizes are designed as basic pattern units when a pattern is drawn on the wafer, and the basic pattern units are arranged at equal intervals, so that when an optical microscope is used for magnifying and observing, the gray scale pattern can be drawn on the wafer. And different expected gray levels can be presented. According to the manufacturing method for manufacturing the gray scale pattern on the wafer, black and white lines or square frames with different widths or sizes are designed to serve as basic pattern units when the pattern is drawn on the wafer, and the basic pattern units are arranged at equal intervals, so that when an optical microscope is used for magnifying and observing, the gray scale pattern can be drawn on the wafer. According to the method, different expected gray levels can be presented, stable regulation and control of the gray levels are realized by directly optimizing graphic structure parameters, the predictability and controllability of the gray levels are improved, and the process complexity and the detection error risk are reduced.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a method for fabricating grayscale patterns on wafers. Background Technology

[0002] In semiconductor wafer manufacturing, after the patterning process is completed, when images are acquired using monochrome imaging equipment, the originally designed pure monochrome pattern will inevitably exhibit varying degrees of grayscale variation due to limitations in optical diffraction and system resolution. This grayscale phenomenon is particularly prominent in high-precision manufacturing environments, directly affecting the accuracy of wafer inspection, defect identification, and metrological analysis. For example, in applications requiring the differentiation of fine structures or the simulation of specific conditions, it is essential to achieve adjustable grayscale output from a monochrome base pattern with the same geometric style to meet different testing requirements.

[0003] However, existing technologies rely solely on external equipment calibration or image post-processing to adjust grayscale, lacking an intrinsic design strategy that can directly generate a preset grayscale effect during optical microscope observation by finely parameterizing basic graphic units (such as line width, box size, and their arrangement). Specifically, when predictable and controllable grayscale is required based on fixed-style black-and-white graphics, traditional methods cannot solve this problem through structural optimization of the graphics themselves, resulting in unstable and difficult-to-reproduce grayscale responses, thereby increasing process complexity and the risk of detection errors.

[0004] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0005] Therefore, the purpose of this invention is to provide a method for fabricating grayscale patterns on wafers, which improves the predictability and controllability of grayscale, and reduces process complexity and detection error risk.

[0006] To solve the above-mentioned technical problems, the present invention provides a method for fabricating grayscale patterns on a wafer, the technical solution of which is as follows: When drawing patterns on a wafer, black and white lines or squares of different widths or sizes are designed as basic graphic units and arranged at equal intervals so that different gray levels can be presented when observed under an optical microscope.

[0007] In one embodiment of the present invention, the box is a black box, and the black boxes are arranged in a rectangular array. The spacing between the rows and columns of the black boxes is equal to the side length of the black boxes, and the spacing between the rows and columns of the black boxes is filled with white.

[0008] In one embodiment of the present invention, the larger the side length of the black box, the smaller the gray value will be when the graphic is magnified and observed through an optical microscope after it is drawn.

[0009] In one embodiment of the present invention, the size of the different grayscale graphics formed by the black and white alternating lines or squares of different widths or sizes is greater than or equal to 1 micrometer.

[0010] In one embodiment of the present invention, when the side length of the black box and the spacing of the black box are 150nm, a 300nm pitch matrix is ​​used to configure the grayscale of the pattern drawn on the wafer to be 200.

[0011] In one embodiment of the present invention, when the side length of the black box and the spacing of the black box are 200nm, a 400nm pitch matrix is ​​used to configure the grayscale of the pattern drawn on the wafer to be 150.

[0012] In one embodiment of the present invention, when the side length of the black box and the spacing of the black box are 250nm, a 300nm pitch matrix is ​​used to configure the gray level of the pattern drawn on the wafer to be 90.

[0013] In one embodiment of the present invention, when the side length of the black box and the spacing of the black box are 300nm, a 600nm pitch matrix is ​​used to configure the gray level of the pattern drawn on the wafer to be 60.

[0014] The method for fabricating grayscale patterns on wafers described above has the following advantages compared to the prior art: When drawing patterns on a wafer, black and white alternating lines or squares of different widths or sizes are designed as basic graphic units and arranged in an equally spaced manner. This allows for the presentation of different gray levels when observed under an optical microscope. By directly optimizing the graphic structure parameters, the gray level can be stably controlled, improving the predictability and controllability of the gray level and reducing the complexity of the process and the risk of detection errors. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 The present invention consists of a pattern composed of squares with a width of 150nm and a height of 150nm arranged in a pitch matrix of 300nm; Figure 2The present invention consists of a pattern composed of squares with a width of 200nm and a height of 200nm arranged in a pitch matrix of 400nm; Figure 3 The present invention consists of a pattern composed of squares with a width of 250nm and a height of 250nm arranged in a pitch matrix of 500nm; Figure 4 The present invention consists of a pattern composed of squares with a width of 300nm and a height of 300nm arranged in a pitch matrix of 600nm; Figure 5 This is a design drawing of the present invention when no pattern is made on the wafer; Figure 6 This is an image of the wafer of the present invention when no pattern is made on it and the grayscale is 240. Figure 7 This is a design drawing of a 40-micron block pattern made on a wafer with a grayscale of 200. Figure 8 This is an image of a 40-micron block pattern made on a wafer of the present invention with a grayscale of 200. Figure 9 This is a design drawing of a 40-micron block pattern made on a wafer with a grayscale of 150. Figure 10 This is an image of a 40-micron block pattern made on a wafer of the present invention with a grayscale of 150. Figure 11 This is a design drawing of a 40-micron block pattern made on a wafer with a grayscale of 90. Figure 12 This is an image of a 40-micron block pattern made on a wafer of the present invention with a grayscale of 90. Figure 13 This is a design drawing of a 40-micron block pattern made on a wafer with a grayscale of 60. Figure 14 This is an image of a 40-micron block pattern made on a wafer of the present invention with a grayscale of 60. Detailed Implementation

[0017] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0018] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] It should be noted that the following description covers various aspects of embodiments within the scope of the appended claims. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0020] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0021] Additionally, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that practice can be carried out without these specific details.

[0022] Traditionally, after the patterning of semiconductor wafers is completed, the images captured by a monochrome camera will exhibit different grayscale levels. However, in specific applications, it is necessary to achieve and present different, pre-defined grayscale levels from monochrome images of the same style. Current technology lacks an effective method to precisely design and arrange basic monochrome images to present different, pre-defined grayscale levels under an optical microscope, thereby meeting specific image grayscale requirements.

[0023] In response, this invention proposes a method for fabricating grayscale patterns on wafers. This method uses black and white alternating lines or squares of different widths or sizes as basic graphic units when drawing patterns on the wafer, and arranges them at equal intervals. This allows the desired different grayscale levels to be displayed when observed under an optical microscope, thus effectively solving the aforementioned technical problems.

[0024] In this context, a wafer is defined as a thin sheet of silicon or other semiconductor material used to manufacture semiconductor devices, serving as the fundamental carrier for integrated circuit manufacturing. A grayscale image is a visually apparent image displaying different brightness or grayscale levels, with grayscale values ​​between pure black and pure white, perceptible through optical observation. Alternating black and white lines or boxes are geometric elements composed of alternating black and white areas; these elements can be elongated lines or squares with a certain area. A basic graphic unit is the smallest repeatable design unit that constitutes a complex grayscale image; its size, shape, and arrangement directly affect the final grayscale effect. Equal spacing refers to the uniform arrangement of basic graphic units on the wafer surface, ensuring the periodicity of the image and the uniformity of grayscale distribution. An optical microscope is an instrument that uses visible light to magnify and observe minute objects; in this method, it is used to observe the grayscale effect of microscopic patterns fabricated on a wafer.

[0025] This method is applied to fabricating grayscale patterns on wafers. Its core lies in achieving controllable grayscale representation under an optical microscope through meticulous pattern design and arrangement. Specifically, when drawing patterns on a wafer, the first step is to design basic pattern units. These basic pattern units can be alternating black and white lines or alternating black and white boxes. For example, a series of black lines of varying widths can be designed and alternated with white gaps of fixed widths; alternatively, a series of black boxes of varying sizes can be designed and staggered with white gaps of fixed sizes. By changing the width of the black lines or the size of the black boxes, their coverage per unit area can be adjusted, thereby affecting the reflection or transmission characteristics of light. Furthermore, these designed basic pattern units need to be arranged with equal spacing. For example, when the basic pattern unit is a line, each black line can maintain the same center-to-center distance or edge-to-edge distance with its adjacent white gap and the next black line; when the basic pattern unit is a box, each black box can maintain the same horizontal and vertical spacing with its adjacent white gap and the next black box. This evenly spaced arrangement ensures the uniformity and predictability of the grayscale effect, avoiding uneven grayscale caused by irregular arrangement.

[0026] Therefore, by using black and white lines or squares of varying widths or sizes as basic graphic units and arranging them at equal intervals, when these graphics are magnified under an optical microscope, the human eye's limited ability to distinguish minute details causes these tiny black and white patterns to be averaged, resulting in different expected grayscale levels. For example, when the coverage of black areas is high, the observed grayscale will be darker; when the coverage of black areas is low, the observed grayscale will be lighter. By precisely controlling the size and arrangement of the basic graphic units, precise control of the final grayscale value can be achieved.

[0027] This method effectively solves the problem in existing technologies of achieving preset and controllable different grayscale levels from black and white graphics of the same style by finely designing black and white lines or squares of different widths or sizes on the wafer as basic graphic units and arranging them at equal intervals. As a result, when observed under an optical microscope, the expected grayscale effect can be accurately presented, meeting the fine requirements for specific image grayscale levels in semiconductor wafer fabrication.

[0028] This application proposes using rectangles as basic graphic units to fabricate grayscale patterns on a wafer. However, during implementation, the arrangement of the rectangles may lack specific rules, resulting in uneven or uncontrollable grayscale rendering. More refined arrangement design is needed to ensure predictability and consistency of grayscale. To address this, this application further proposes a method for fabricating grayscale patterns on a wafer, wherein the rectangles are black rectangles arranged in a rectangular array. The spacing between rows and columns of the black rectangles is equal to the side length of the black rectangles, and the spacing between rows and columns of the black rectangles is filled with white.

[0029] Specifically, the boxes are defined as black boxes. As the basic unit constituting grayscale graphics, the black boxes are limited to black, providing maximum contrast against a white background, which is crucial for grayscale recognition under an optical microscope. In practice, photolithography selectively exposes and develops the photoresist, allowing the areas where black boxes need to be formed to retain opaque material while other areas are removed, thus creating black boxes on the wafer surface. Alternatively, in the deposition process, a mask can be used to define the deposition area, ensuring that black material is deposited only in the box areas, forming black boxes. The black boxes are arranged in a rectangular array. This means that the black boxes are arranged regularly on the wafer surface in rows and columns according to a pre-defined two-dimensional grid structure. This arrangement ensures the orderliness and repeatability of the graphic units, laying the foundation for uniform distribution and precise control of grayscale values. During the mask design stage, computer-aided design (CAD) tools can be used to lay out the pattern of the black boxes according to precise rectangular coordinates, generating a mask for photolithography. Alternatively, in direct writing techniques such as electron beam lithography or ion beam etching, the scanning path of the electron or ion beam is programmed to draw black squares arranged in a rectangular array on the wafer surface. The spacing between rows and columns of the black squares is equal to the side length of the black square. This spacing is consistent with the side length of the black square itself in both the horizontal (between columns) and vertical (between rows) directions. By precisely controlling the ratio of black squares to white spacing, the proportion of black area per unit area is directly determined, thereby achieving precise quantitative control of grayscale values. This proportional design helps to form a uniform grayscale transition. During mask design, the size of each black square can be precisely set, and the spacing between adjacent squares can be calculated based on this size to ensure that the spacing is consistent with the side length of the square. For example, if the side length of the square is L, then the center-to-center spacing between adjacent squares is 2L. During photolithography or etching, a high-precision alignment and exposure system ensures the accuracy of pattern transfer, so that the actual formed black squares and their spacing strictly meet the design requirements. The spacing between rows and columns of the black squares is filled with white. This means that the gaps between the black boxes are white. This white filling ensures that the areas between the black boxes are a pure white background, maximizing black-and-white contrast and preventing stray light or background color from interfering with grayscale observation, thus making grayscale representation clearer and more controllable. In photolithography, the wafer substrate or the dielectric layer above it is usually white or transparent. The black box areas are formed through photolithography and etching processes, while the areas not covered by the black boxes naturally exhibit the white of the substrate. Alternatively, after the black boxes are formed, a white or transparent passivation layer or dielectric layer can be deposited across the entire surface. Then, a planarization process (such as chemical mechanical polishing, CMP) can be used to remove the white layer on top of the black boxes, revealing the black boxes while the gaps remain white-filled.

[0030] In the aforementioned scheme, this application addresses the problem of inaccurate grayscale control by specifically defining the color, arrangement, and filling rules of the boxes, achieving a more reliable and uniform grayscale presentation. Specifically, the boxes are defined as black boxes, which helps to create high contrast against a white background, facilitating clear differentiation of grayscale under an optical microscope; the black boxes are arranged in a rectangular array, ensuring the regular arrangement of graphic units and avoiding uneven grayscale caused by random arrangement; the spacing between rows and columns containing the black boxes is equal to the side length of the black boxes, creating a balanced pattern proportion and fixing the ratio of black and white areas, thereby precisely controlling the grayscale value; the spacing between rows and columns containing the black boxes is filled with white, which enhances the pure white of the background, optimizes contrast, and makes grayscale observation clearer and more controllable. These features work together to improve the predictability and consistency of grayscale.

[0031] This application proposes using black rectangles arranged in a rectangular array to achieve grayscale control. However, the lack of a clear correspondence between dimensions and grayscale values ​​in its implementation makes it impossible to precisely guide how to adjust the rectangle's side length to achieve the desired grayscale effect. Therefore, this application further proposes that the larger the side length of the black rectangle, the smaller the grayscale value will appear when the image is magnified and observed under an optical microscope after drawing.

[0032] Specifically, "the larger the side length of the black box" refers to the physical size of the black box—the basic unit that makes up a grayscale image. When drawing patterns on a wafer, the side length of these black boxes can be precisely controlled by adjusting the design parameters of the photomask. For example, refer to... Figure 1-4As shown, during the design phase, different side length values, such as 150nm, 200nm, 250nm, or 300nm, can be set to generate arrays of black boxes with different sizes. This adjustment of size directly affects the ability of the black area to absorb or reflect light at the microscopic scale, and is a key physical parameter for achieving grayscale control. The phrase "the smaller the grayscale value observed under magnification through an optical microscope after drawing the image" describes the optical observation effect caused by changes in the side length of the black boxes. Under an optical microscope, grayscale value is a quantitative representation of image brightness; generally, smaller grayscale values ​​correspond to darker areas, while larger grayscale values ​​correspond to brighter areas. When the side length of the black box increases, even if its ratio to the white interval remains unchanged (e.g., in some embodiments, the interval is equal to the side length), due to factors such as optical diffraction, resolution limitations, and the point spread function of the microscope imaging system, a larger black box will exhibit stronger light absorption or less reflection under an optical microscope, thus making the observed area appear darker overall, i.e., exhibiting a smaller grayscale value. This phenomenon allows for precise control of grayscale by adjusting the absolute size of the box, rather than just its relative duty cycle.

[0033] Through the above technical solution, this application clearly establishes a direct inverse relationship between the side length of the black box and the final grayscale value. When drawing patterns on a wafer, designers can simply increase the side length of the black box to obtain a smaller grayscale value (i.e., a darker visual effect) under an optical microscope. This explicit size-grayscale correspondence solves the problem in the prior art of lacking precise guidance on how to adjust the box size to achieve the desired grayscale effect. Given that in the above embodiment, the black boxes are arranged in a rectangular array with row and column spacing equal to the side length, this means that while maintaining the basic pattern structure proportions, by adjusting the absolute size of the black boxes, the imaging characteristics of the optical microscope at subwavelength or near-diffraction limits can be utilized to make larger black boxes appear to have lower brightness (smaller grayscale values). This makes the control of grayscale values ​​no longer solely dependent on the relative proportions of black and white areas, but can be achieved by adjusting the absolute size of the basic graphic unit. Therefore, this application provides an intuitive and predictable grayscale control mechanism, which allows designers to precisely select or design black boxes of appropriate side lengths according to the desired grayscale effect, thereby avoiding random trials and uncertainties, significantly improving the efficiency and accuracy of grayscale graphic design, and ensuring that grayscale graphics fabricated on wafers can accurately present the expected grayscale effect.

[0034] This application proposes to represent different gray levels by adjusting the side length of the black squares. However, in its implementation, if the graphic size is too small, it may be impossible to clearly distinguish or reliably represent the gray level under an optical microscope, affecting the precise control and observability of the gray level. Therefore, this application further proposes that the size of the different gray level graphics composed of black and white alternating lines or squares of different widths or sizes is greater than or equal to 1 micrometer.

[0035] Specifically, grayscale patterns composed of alternating black and white lines or boxes of varying widths or sizes refer to composite patterns of different grayscale levels that can be observed under an optical microscope by designing these lines or boxes as basic graphic units on a wafer and arranging them at equal intervals. This results in a desired grayscale effect. The graphic is the fundamental visual unit for achieving the grayscale effect, and the proportion and arrangement of the black and white patterns within it determine the final grayscale value. The size of the graphic is greater than or equal to 1 micrometer to ensure that the grayscale graphic has sufficient physical size under an optical microscope, avoiding observation difficulties or grayscale distortion due to excessively small size. For example, if the graphic size is too small, it may be affected by the optical diffraction limit, resulting in blurred edges or the camera sensor not being able to capture enough pixel information to accurately calculate the grayscale value. By setting a size of at least 1 micrometer, the optical system can effectively resolve graphic details and provide sufficient sampling area for image acquisition, thus ensuring stable and repeatable grayscale values. Furthermore, this size limitation also helps ensure the consistency of the visual effect and measurement results of the grayscale graphic at different magnifications.

[0036] Through the above technical solution, this application effectively solves the technical problem that small-sized patterns may not be effectively distinguishable and grayscale under an optical microscope. Specifically, by limiting the lower limit of the size of different grayscale patterns to greater than or equal to 1 micrometer, it ensures that the basic graphic units used to generate grayscale have sufficient physical size when observed under magnification with an optical microscope. This avoids problems such as blurred details, diffraction effects, or insufficient sampling by the image sensor caused by excessively small pattern size, thereby ensuring clear grayscale presentation and precise controllability. This solution significantly improves the observability, measurement accuracy, and overall reliability and practicality of grayscale patterns in the wafer fabrication process, enabling the stable and accurate realization and presentation of preset grayscale values ​​on semiconductor wafers.

[0037] Reference Figure 5 , 6 As shown, one embodiment is a grayscale of 240 in the area on the wafer where no pattern is applied.

[0038] Based on the first embodiment proposed in this application, referring to... Figure 7 , 8As shown, when the side length and spacing of the black boxes are 150nm, a 300nm pitch matrix is ​​used to configure the grayscale of the pattern drawn on the wafer to be 200.

[0039] In this technical solution, the side length and spacing of the black boxes are both 150nm, defining the physical size and adjacent spacing of the basic unit constituting the grayscale pattern—the black boxes. Specifically, the side length of the black boxes is set to 150nm, and the spacing between them is also set to 150nm. This precise nanoscale size control is fundamental to achieving specific grayscale values. In practice, this can be achieved through various high-precision micro / nano fabrication techniques. For example, electron beam lithography (EBL) can be used to form a 150nm pattern on photoresist by precisely controlling the scanning path and dosage of the electron beam, and then transferring the pattern to the wafer through development, etching, and other processes. Alternatively, deep ultraviolet (DUV) lithography, combined with advanced mask design and process optimization, can be used to achieve precise replication of the 150nm size. A 300nm pitch matrix is ​​used to configure the pattern drawing on the wafer, further defining the arrangement of the aforementioned black box units on the wafer. The "pitch matrix" refers to the repetition period or center-to-center spacing of the pattern units in the array. Here, a 300nm pitch matrix means that each black square unit (including its 150nm side length and 150nm spacing) has a repetition period of 300nm in both the horizontal and vertical directions. This periodic arrangement ensures the uniformity and repeatability of the pattern, which is key to achieving a stable grayscale effect. This arrangement can be achieved by using individual black square units with 150nm side length and 150nm spacing as the basic pattern during the mask design stage, and replicating them in a two-dimensional array with a period of 300nm. During the photolithography process, the lithography machine precisely replicates these units onto the wafer surface with a 300nm pitch matrix according to the design on the mask. A grayscale of 200 clearly defines the desired optical effect achieved through the aforementioned dimensions and arrangement: a grayscale value of 200 when observed under an optical microscope. Grayscale values ​​typically range from 0 (pure black) to 255 (pure white), and a grayscale of 200 represents a relatively bright grayscale, close to white. This value is precisely designed and verified, representing the optical response of a specific physical structure under specific observation conditions. To verify and achieve this grayscale value, optical measurements and calibrations are typically required. For example, after a pattern is fabricated on a wafer, a high-resolution CCD or CMOS camera is used in conjunction with an optical microscope to acquire images. Image processing software is then used to perform grayscale analysis on the acquired images and calculate their average grayscale value. If the actual measured value deviates from the target value of 200, the side length, spacing, or pitch matrix of the black boxes need to be fine-tuned until the desired grayscale effect is achieved.

[0040] The above technical solution addresses the problem of lacking specific size and arrangement parameters for precise grayscale configuration when fabricating grayscale patterns on wafers. This application provides a concrete and quantifiable solution. By setting the side length and spacing of the black boxes to 150nm and arranging them precisely with a 300nm pitch matrix, a grayscale pattern of 200 can be stably and repeatedly fabricated on the wafer. This precise parameterized design avoids the grayscale deviation and trial-and-error costs caused by unclear parameters in traditional methods, ensuring that the grayscale values ​​of the fabricated pattern are highly consistent with expectations. This not only improves the efficiency and accuracy of grayscale pattern fabrication but also provides a reliable technical foundation for applications requiring specific optical responses, making the grayscale effects observed under an optical microscope highly controllable and predictable.

[0041] Based on the second embodiment proposed in this application, referring to... Figure 9 , 10 As shown, when the side length and spacing of the black boxes are 200nm, a 400nm pitch matrix is ​​used to configure the grayscale of the pattern drawn on the wafer to be 150.

[0042] Specifically, the side length of the black box refers to the individual side length of the basic black unit that constitutes the grayscale pattern. When patterning on the wafer, this side length is achieved through high-precision photolithography or electron beam etching and other micro / nano fabrication techniques, ensuring its size is precisely controlled within 200 nm. This size is a fundamental physical parameter for achieving a specific grayscale value and directly affects the proportion of black area per unit area. The spacing of the black boxes refers to the net distance between adjacent black boxes. In the aforementioned rectangular array arrangement, this spacing can be the interval between rows or columns. This spacing is also achieved through precise pattern design and micro / nano fabrication processes, for example, by adjusting the pattern layout on the mask or controlling exposure and development parameters. This spacing, equal to the side length of the black boxes, helps maintain the periodicity and uniformity of the pattern, thus presenting a stable grayscale effect under an optical microscope. The "pitch matrix" refers to the periodic repeating of black boxes on the wafer. Specifically, a 400 nm pitch matrix means that the center-to-center distance of each repeating unit (e.g., a black box and its adjacent white spacing) is 400 nm. This periodic arrangement utilizes the diffraction-limited effect of an optical microscope, optically averaging tiny black and white patterns to achieve a continuous grayscale appearance on a macroscopic scale. The pitch matrix setting can be precisely defined using mask design software and strictly executed during the photolithography process. "Grayscale 150" refers to the brightness value presented when the drawn image is observed under an optical microscope. In common 8-bit grayscale images, grayscale values ​​typically range from 0 (pure black) to 255 (pure white). Grayscale 150 represents a specific intermediate grayscale, with brightness between pure black and pure white, leaning more towards white. This grayscale value is the final optical representation of the combined effect of the aforementioned side lengths, spacing, and pitch matrix, and can be quantitatively measured using an image acquisition system and grayscale analysis software.

[0043] By precisely setting the side length and spacing of the black boxes to 200nm and periodically configuring them according to a 400nm pitch matrix, this application achieves precise control of the grayscale of the pattern drawn on the wafer at 150. This specific parameter combination overcomes the limitation of the lack of precise grayscale configuration parameters in the prior art. By setting the side length of the black boxes to 200nm, combined with the inverse relationship between side length and grayscale value in the above scheme, the grayscale value can be effectively controlled. At the same time, setting the spacing of the black boxes to 200nm ensures that the black boxes are evenly spaced in the rectangular array, thereby optimizing the uniformity of the pattern under the optical microscope and avoiding the problem of grayscale inconsistency caused by uneven spacing. Furthermore, by using a 400nm pitch matrix, the periodic arrangement of the pattern units is precisely defined, so that under the optical microscope, the tiny black and white patterns can stably and repeatedly present the target grayscale of 150 through the optical averaging effect. This precise parametric design avoids the blind setting of parameters in actual operation, significantly improves the accuracy and controllability of grayscale image production, and thus can meet specific image grayscale requirements.

[0044] Based on the third embodiment proposed in this application, and referring to... Figure 11 , 12 As shown, when the side length and spacing of the black boxes are 250nm, a 300nm pitch matrix is ​​used to configure the grayscale of the pattern drawn on the wafer to be 90.

[0045] Specifically, the black squares have a side length of 250nm. As the basic unit size constituting the grayscale pattern, this directly affects the overall density of the pattern and the ratio of light reflection or transmission observed under an optical microscope. Setting it to 250nm aims to provide fine dimensional control to achieve specific grayscale effects. This side length can be precisely formed on the wafer using high-precision photolithography techniques, such as electron beam lithography or deep ultraviolet lithography; or it can be transferred to the wafer surface using nanoimprint lithography, utilizing a template with a 250nm square pattern. The 250nm spacing between the black squares refers to the distance between adjacent black squares, which, together with the side length of the black squares, determines the periodicity and fill density of the pattern. Setting it to 250nm ensures the ratio of black squares to white filled areas within a specific period, thus affecting the overall grayscale performance. This spacing can be precisely set during the graphic design stage using computer-aided design (CAD) software, ensuring a 250nm distance between the edges of adjacent boxes; or during the photolithography mask fabrication process, using high-resolution mask fabrication equipment to ensure a pattern spacing accuracy of 250nm. A 300nm pitch matrix is ​​used for configuration, defining the periodicity of the black boxes' arrangement on the wafer, i.e., the minimum distance between each basic unit (the black box and its adjacent spacing). A 300nm pitch matrix means that the starting point of a box pattern repeats every 300nm in both the horizontal and vertical directions, ensuring equidistant arrangement and overall uniformity of the pattern. This configuration can be used in the photolithography process to precisely control the stepping and repetition accuracy of the exposure equipment, allowing the black boxes to be arrayed in a 300nm period; or in the pattern generation algorithm, using 300nm as the size of the basic repeating unit to automatically generate pattern data that meets this pitch requirement. The grayscale value of the pattern drawn on the wafer is configured to be 90. Grayscale 90 refers to the specific brightness value of the pattern drawn on the wafer when observed under an optical microscope. A configuration of 90 indicates that the desired medium-dark grayscale effect is achieved through the combination of the aforementioned dimensions and spacing. This grayscale value can be verified experimentally. By setting the side length and spacing of the black boxes to 250 nm and arranging them in a 300 nm pitch matrix, the grayscale value of the pattern on the wafer can be measured using a standard grayscale measurement device to confirm that it reaches 90. Alternatively, during the pattern design phase, simulation software can be used to simulate the optical response under different dimensions and arrangement parameters, predicting and optimizing parameter combinations to achieve the target grayscale of 90.

[0046] By setting the side length of the black boxes to 250nm and precisely controlling their spacing to 250nm, while employing a 300nm pitch matrix for arrangement, this application can precisely control the overall optical density and light reflection / transmission ratio of the patterns drawn on the wafer. This specific combination of size and arrangement parameters allows for a stable and reliable presentation of the preset grayscale level 90 under an optical microscope. This solves the problem of the lack of specific size parameters in the prior art to achieve precise grayscale values, thereby meeting the precise control requirements of grayscale graphics in specific application scenarios and ensuring the accuracy and repeatability of graphic production.

[0047] Based on the fourth embodiment proposed in this application, and referring to... Figure 13 , 14 As shown, when the side length and spacing of the black boxes are 300nm, a 600nm pitch matrix is ​​used to configure the grayscale of the pattern drawn on the wafer to be 60.

[0048] This technology clearly defines the geometric dimensions of the basic unit constituting grayscale patterns—the black squares—and their relative positions within the array. Specifically, the side length of the black square is set to 300 nm, directly determining the physical size of a single black square on the wafer surface. Simultaneously, the spacing between the black squares is also set to 300 nm, meaning a 300 nm white area is left between adjacent black squares. This precise dimensional definition can be achieved through the design of high-precision photolithography masks, for example, by etching patterns with 300 nm linewidths and 300 nm spacing onto the mask using electron beam lithography or deep ultraviolet lithography. Alternatively, nanoimprint lithography can be used to transfer these precisely sized patterns to the wafer surface using a mold with corresponding nanostructure patterns.

[0049] This technical feature further defines the periodic arrangement of the black squares and the resulting grayscale value. A 600nm pitch matrix refers to the periodic length of a repeating unit formed by a black square and its adjacent white spacing when drawing a pattern on a wafer. Given that the side length and spacing of the black squares are both 300nm, a complete repeating unit (one black square plus one white spacing) is exactly 300nm + 300nm = 600nm, thus forming a periodic black and white pattern. This periodic arrangement can be achieved through the step-and-repeat exposure function of the photolithography equipment, ensuring a uniform distribution of the pattern on the wafer. Through this specific combination of size and arrangement, a visual effect with a grayscale value of 60 can be accurately presented when observed under an optical microscope. This grayscale value is obtained by integrating and averaging the black and white pattern using the imaging system of the optical microscope, reflecting the ratio of black to white areas per unit area and its visual perception under specific optical conditions.

[0050] The above technical solution precisely sets the side length and spacing of the black squares to 300nm and uses a 600nm pitch matrix for periodic arrangement, thereby drawing a pattern with a specific grayscale value on the wafer. Specifically, when the side length and spacing of the black squares are both 300nm, it conforms to the principle proposed in the aforementioned solution that "the larger the side length of the black square, the smaller the grayscale value displayed when the pattern is magnified under an optical microscope." By finely controlling the ratio of black and white areas, precise control of the grayscale value is achieved. The 600nm pitch matrix ensures the periodic repetition of the black and white pattern, so that when light passes through these microstructures under an optical microscope, due to diffraction and interference effects, it ultimately presents a stable and predictable grayscale value. This precise combination of size and arrangement parameters allows the pattern drawn on the wafer to stably present a grayscale of 60, thus solving the problem of inaccurate grayscale control caused by the lack of specific parameters in existing technologies. This greatly improves the accuracy and controllability of grayscale pattern production and meets the requirements for precise grayscale values ​​in specific application scenarios.

[0051] Based on the above, in the semiconductor wafer manufacturing process, it is sometimes necessary to create patterns with specific and controllable grayscale values ​​on a wafer to meet the needs of applications such as optical sensor calibration or specific display applications. Existing technologies that create black and white patterns on wafers may exhibit different grayscale levels when observed under an optical microscope, but these grayscale levels are often accidental and uncontrollable, making it difficult to precisely achieve the preset grayscale level.

[0052] This method provides a solution. For example, to create a gradient area from light gray to dark gray on a wafer, the following steps can be taken: First, areas requiring different shades of gray are planned on the wafer. Within these areas, instead of directly drawing different shades of gray, a series of tiny black and white rectangles are designed as basic graphic units. These rectangles are designed as black rectangles and arranged in a rectangular array. To ensure the uniformity and controllability of the grayscale effect, the spacing between rows and columns containing the black rectangles is designed to be equal to the side length of the black rectangles, and these spacing areas are filled with white. This means that within a local area, the area ratio of black rectangles to white spacing is controllable.

[0053] Specifically, to achieve different grayscale values, the side lengths of these black boxes can be changed. For example, in an area that needs to display a lighter grayscale, the side lengths of the black boxes can be designed to be smaller. When both the side length of the black boxes and the spacing between them are 150nm, and configured with a 300nm pitch matrix, the area will appear as a grayscale of 200 when observed under an optical microscope (a higher grayscale value indicates a brighter area).

[0054] In another area where a deeper grayscale is needed, the black boxes can be designed to have a larger side length. For example, when both the side length and the spacing between the black boxes are 300nm, and a 600nm pitch matrix is ​​used, the area will appear as a grayscale of 60 when observed under an optical microscope (the smaller the grayscale value, the darker it is).

[0055] The design principle is that when the size of these tiny black and white squares is close to or smaller than the resolution limit of an optical microscope, the microscope or its accompanying image acquisition system cannot distinguish individual black squares and white intervals during observation; instead, it averages the light intensity within a local area. Therefore, by changing the side length of the black square (while keeping it equal to the white interval), the ratio of black to white area per unit area is effectively changed. The larger the side length of the black square, the higher the proportion of black area per unit area, the less light is reflected or transmitted, and thus the smaller the gray value appearing under the optical microscope, i.e., the darker it appears. Conversely, the smaller the side length of the black square, the lower the proportion of black area, the larger the gray value appearing, i.e., the brighter it appears.

[0056] In this way, this method enables precise control of the grayscale representation of patterns on a wafer. Compared to existing technologies that struggle to precisely control grayscale or can only present fixed grayscale values, this method achieves preset and controllable different grayscale values ​​under an optical microscope through the meticulous design and equidistant arrangement of basic black and white pattern units. Furthermore, to ensure the macroscopic recognizability of the resulting grayscale patterns, the overall size of these different grayscale patterns, composed of black and white alternating lines or squares of varying widths or sizes, is designed to be greater than or equal to 1 micrometer. This method provides an effective and repeatable means to meet the demand for precise grayscale patterns in semiconductor manufacturing.

[0057] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for fabricating grayscale patterns on a wafer, characterized in that: When drawing patterns on a wafer, black and white lines or squares of different widths or sizes are designed as basic graphic units and arranged at equal intervals so that different gray levels can be presented when observed under an optical microscope.

2. The method for fabricating grayscale patterns on a wafer according to claim 1, characterized in that: The boxes are black boxes, and the black boxes are arranged in a rectangular array. The spacing between the rows and columns of the black boxes is equal to the side length of the black boxes, and the spacing between the rows and columns of the black boxes is filled with white.

3. The method for fabricating grayscale patterns on a wafer according to claim 2, characterized in that: The larger the side length of the black box, the smaller the gray value will be when the graphic is magnified and observed through an optical microscope after it is drawn.

4. The method for fabricating grayscale patterns on a wafer according to claim 3, characterized in that: The size of the different grayscale graphics formed by the black and white alternating lines or squares of different widths or sizes is greater than or equal to 1 micrometer.

5. The method for fabricating grayscale patterns on a wafer according to claim 3, characterized in that: When the side length and spacing of the black boxes are 150nm, a 300nm pitch matrix is ​​used to configure the grayscale of the pattern drawn on the wafer to be 200.

6. The method for fabricating grayscale patterns on a wafer according to claim 3, characterized in that: When the side length and spacing of the black boxes are 200nm, a 400nm pitch matrix is ​​used to configure the grayscale of the pattern drawn on the wafer to be 150.

7. The method for fabricating grayscale patterns on a wafer according to claim 3, characterized in that: When the side length and spacing of the black boxes are 250nm, a 300nm pitch matrix is ​​used to configure the grayscale of the pattern drawn on the wafer to be 90.

8. The method for fabricating grayscale patterns on a wafer according to claim 3, characterized in that: When the side length and spacing of the black boxes are 300nm, a 600nm pitch matrix is ​​used to configure the grayscale of the pattern drawn on the wafer to be 60.

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