Moire alignment mark and alignment device

Abstract

The application provides a Moire alignment mark and an alignment device, the Moire alignment mark comprises a plurality of first stripe structures extending along a first direction and arranged along a second direction, the first stripe structure comprises a first light-transmitting strip and a first non-light-transmitting strip arranged adjacently along the second direction; along a positive direction of the second direction and a negative direction of the second direction of a center of the Moire alignment mark, the width of the first light-transmitting strip and / or the first non-light-transmitting strip changes according to a first preset rule. The Moire alignment mark provided by the application can be used in a Moire stripe-based alignment device, solves the technical problem that the Moire alignment mark with equal-interval stripes only has a fixed spatial period and can only realize small-range alignment, solves the problem that the Moire alignment mark with equal-interval stripes lacks an absolute center and relies on a coarse alignment mark, and the period of the stripe structure of the Moire alignment mark is not constant in space, so the Moire stripe has no period repetition and can realize large-range identification and alignment.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and more particularly to a moiré alignment mark and alignment device. Background Technology

[0002] In the photolithography process of semiconductor manufacturing, precise alignment between the mask and the wafer is a critical step that determines chip yield and device performance. Moiré fringe alignment technology has become an important method in the field of precision alignment due to its unique advantages of nanometer-level alignment accuracy and measurement accuracy being independent of wafer-mask gap and light source wavelength.

[0003] Moiré fringes are visible fringes with lower spatial frequencies than the original patterns, produced when two patterns with similar spatial frequencies are superimposed. A typical implementation involves fabricating equally spaced line grating alignment marks on a mask and a wafer, with slight differences in their fringe periods. When these two lines are brought close together at a certain distance and illuminated, the diffracted light interferes to form moiré fringes. The offset information between the two patterns is obtained by demodulating the phase change of the moiré fringes.

[0004] The aforementioned moiré fringe alignment scheme based on equally spaced gratings has a limitation: because the period of the grating is equal everywhere, the resulting moiré fringes are completely periodic, without an absolute, uniquely identifiable center position. This directly leads to the problem that existing calculations rely on external references and have a limited alignment range. Therefore, there is an urgent need for a new alignment mark structure that retains the high sensitivity alignment advantage of moiré fringes while also possessing self-reference center positioning capability. Summary of the Invention

[0005] This invention provides a moiré alignment mark and an alignment device. The moiré alignment mark can be used in an alignment device based on moiré fringes, solving the technical problem that the moiré alignment mark with equidistant stripes has only a fixed spatial period and can only achieve small-range alignment, as well as the problem that the moiré alignment mark with equidistant stripes lacks an absolute center and relies on a coarse alignment mark. The period of the stripe structure of the alignment mark is not constant in space, so the moiré fringes have no periodic repetition and can achieve a larger range of recognition and alignment.

[0006] According to one aspect of the present invention, a moiré alignment mark is provided, comprising a plurality of first stripe structures extending along a first direction and arranged along a second direction, wherein the first stripe structure includes a first light-transmitting strip and a first non-light-transmitting strip arranged adjacent to each other along the second direction, and the first direction intersects the second direction; The widths of the first light-transmitting strip and / or the first non-light-transmitting strip vary according to a first preset rule along the positive direction from the center of the moiré alignment mark to the second direction and along the negative direction from the center of the moiré alignment mark to the second direction.

[0007] Optionally, it also includes a plurality of second stripe structures extending along the second direction and arranged along the first direction, wherein the second stripe structure includes a second light-transmitting strip and a second non-light-transmitting strip arranged adjacent to each other along the first direction; The widths of the second light-transmitting strip and / or the second non-light-transmitting strip vary according to a second preset rule along the positive direction from the center of the moiré alignment mark to the first direction and along the negative direction from the center of the moiré alignment mark to the first direction.

[0008] Optionally, the moiré alignment mark includes a first alignment mark and a second alignment mark, wherein the first alignment mark and the second alignment mark generate moiré fringes when they overlap in a third direction, and the third direction is perpendicular to the plane in which the first alignment mark is located; The extension direction of the first light-transmitting strip in the first alignment mark and the extension direction of the first light-transmitting strip in the second alignment mark have a preset angle.

[0009] Optionally, the stripe structure distribution in the first alignment mark and the second alignment mark is the same, or at least one of the distribution patterns of the light-transmitting or non-light-transmitting stripes in the stripe structure of the first alignment mark and the second alignment mark is different.

[0010] Optionally, the first preset rule includes one of the following rules: linear increase, linear decrease, nonlinear increase, nonlinear decrease, or non-monotonic change according to a preset function rule; The second preset rule includes one of the following rules: linear increase, linear decrease, nonlinear increase, nonlinear decrease, or non-monotonic change according to the preset function rule.

[0011] According to another aspect of the present invention, an alignment device is provided, comprising an illumination component, an alignment mark component, and a detection component, wherein the alignment mark component includes a first mark and a second mark, the first mark being located on a workpiece to be aligned, and the second mark being located on a workpiece serving as a reference, the first mark and the second mark being determined according to the above-described Moiré alignment mark; The illumination component is used to output an illumination beam, and the illumination beam, after passing through the first mark and the second mark, forms a moiré fringe that is incident on the detection component. The detection component analyzes and calculates based on the detected moiré fringes, and moves the position of the workpiece to be aligned until the first mark and the second mark are aligned.

[0012] Optionally, the detection component includes a detector and a processing unit. The detector is used to receive the moiré fringes, and the processing unit is used to analyze and calculate based on the signal from the detector, and move the position of the workpiece to be aligned.

[0013] Optionally, the detector may include a camera.

[0014] Optionally, the detector includes an area array light intensity detector.

[0015] Optionally, the detector may include a linear array of light intensity detectors.

[0016] The moiré alignment mark provided in this invention includes multiple first stripe structures extending along a first direction and arranged along a second direction. Each first stripe structure includes a first translucent strip and a first opaque strip arranged adjacent to each other along the second direction, with the first and second directions intersecting. The widths of the first translucent strip and / or the first opaque strip vary according to a first preset rule along the positive direction from the center of the moiré alignment mark to the second direction and along the negative direction from the center of the moiré alignment mark to the second direction. By setting the widths of the first translucent strip and / or the first opaque strip to vary according to the first preset rule, a stripe structure with gradually changing spacing and / or line width is achieved. This stripe structure gradually changes spacing and / or line width from the center to both sides according to a certain rule. When two moiré alignment marks form moiré stripes, there is no periodic repetition, enabling identification and alignment over a large range. Furthermore, the moiré stripes have a unique absolute center and do not require reliance on external coarse alignment marks.

[0017] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the moiré fringes corresponding to the alignment marks of two line gratings in the prior art; Figure 2 A schematic diagram of a first alignment mark provided in an embodiment of the present invention; Figure 3 A schematic diagram of a second alignment mark provided in an embodiment of the present invention; Figure 4 for Figure 2 The first alignment mark and Figure 3 A schematic diagram of the moiré fringes generated by the second alignment mark in the middle; Figure 5 A schematic diagram of another first alignment mark provided in an embodiment of the present invention; Figure 6 A schematic diagram of another second alignment mark provided in an embodiment of the present invention; Figure 7 for Figure 5 The first alignment mark and Figure 6 A schematic diagram of the moiré fringes generated by the second alignment mark in the middle; Figure 8 This is an overall schematic diagram of an alignment device provided in an embodiment of the present invention; Figure 9 This is an overall schematic diagram of another alignment device provided in an embodiment of the present invention; Figure 10 This is a schematic diagram of the image after moiré fringe filtering. Figure 11 This is a schematic diagram of a binarized image; Figure 12 This is a schematic diagram of the image under ideal positioning. Figure 13 This is a schematic diagram of a binary physical mask; Figure 14 A schematic diagram of the distribution of a linear array optical intensity detector provided in an embodiment of the present invention; Figure 15 This is a schematic diagram of a wafer alignment device in a lithography machine provided in an embodiment of the present invention; Figure 16 This is a schematic diagram of a precision alignment device for machined parts provided in an embodiment of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0021] It should be noted that the terminology used in the embodiments of this invention is for the purpose of describing specific embodiments only and is not intended to limit the invention. It should be noted that directional terms such as "above," "below," "left," and "right" described in the embodiments of this invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this invention. Furthermore, in the context, it should be understood that when referring to an element being formed "above" or "below" another element, it can be formed not only directly "above" or "below" the other element, but also indirectly "above" or "below" the other element through an intermediate element. The terms "first," "second," etc., are used for descriptive purposes only and do not indicate any order, quantity, or importance, but are only used to distinguish different components. It should be understood that such terms can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0022] Figure 1 The diagram shows the moiré fringes corresponding to the alignment marks of two line gratings in the prior art. In the prior art, both line gratings are equally spaced gratings, which has the following problems: (1) Dependence on external reference: Since the alignment mark itself has no absolute center, in the actual alignment process, it is usually necessary to use external reference marks (such as cross-shaped marks) for coarse pre-alignment to reduce the initial offset to within the capture range of fine alignment, and then switch to using moiré fringes for fine alignment. This not only increases the complexity of the alignment steps, but also limits the alignment efficiency and reliability. (2) Limited alignment range: Since the moiré fringe signal has a periodic repetition characteristic, when the movement of the alignment mark causes the moiré fringe offset to exceed half of the fringe period, a periodic ambiguity problem will occur, and the correct offset cannot be uniquely determined. The measurement range of the traditional scheme is limited to the order of a few micrometers (about half of the alignment mark period), which is difficult to meet the large-range alignment requirements.

[0023] To address the technical problems of equally spaced striped moiré alignment marks (including two alignment marks) having only a fixed spatial period, enabling only small-scale alignment, and the lack of an absolute center in equally spaced striped moiré alignment marks, relying on coarse alignment marks, this invention provides a moiré alignment mark comprising multiple first stripe structures extending along a first direction and arranged along a second direction. The first stripe structure includes a first translucent strip and a first non-translucent strip arranged adjacent to each other along the second direction, with the first direction intersecting the second direction. The widths of the first translucent strip and / or the first non-translucent strip vary according to a first preset rule along the positive direction from the center of the moiré alignment mark to the second direction and along the negative direction from the center of the moiré alignment mark to the second direction.

[0024] It is understandable that the first stripe structure can be regarded as a periodically changing grating structure, thus including multiple first transparent stripes and first opaque stripes designed alternately along the second direction. Unlike a constant grating structure, the width of the first transparent stripe and / or the first opaque stripe varies according to a first preset law. In specific implementation, the first preset law can be designed according to the actual situation. Optionally, the first preset law includes one of the following laws: linear increase, linear decrease, nonlinear increase, nonlinear decrease, or non-monotonic change according to a preset function law. For example, the width of the first transparent stripe can be designed to increase linearly, decrease linearly, increase nonlinearly (e.g., according to a quadratic function law or a higher-order function law), decrease nonlinearly, or change non-monotonicly according to a preset function (e.g., a trigonometric function), such as first increasing and then decreasing, first decreasing and then increasing, or first increasing and then remaining constant. The width design law of the first opaque stripe is similar, and can be designed according to the actual situation in specific implementation. In actual design, the width of the first light-transmitting strip can be kept constant while the width of the first non-light-transmitting strip varies, or the width of the first light-transmitting strip varies while the width of the first light-transmitting strip remains constant, or the widths of both the first light-transmitting strip and the first non-light-transmitting strip vary. The specific trends or patterns of change of the widths of the first light-transmitting strip and the first non-light-transmitting strip can be the same or different.

[0025] The technical solution of this invention achieves a stripe structure with gradually varying spacing and / or line width by setting the width of the first light-transmitting strip and / or the first non-light-transmitting strip to vary according to a first preset rule. The spacing and / or line width of the stripe structure gradually change from the center to both sides according to a certain rule. When two moiré alignment marks form moiré stripes, there is no periodic repetition, which can achieve a large range of identification and alignment. Moreover, the moiré stripes have a unique absolute center and do not need to rely on external coarse alignment marks.

[0026] For example, Figure 2 This is a schematic diagram of a first alignment mark provided in an embodiment of the present invention, with reference to... Figure 2The moiré alignment mark includes multiple first stripe structures 10 extending along a first direction x and arranged along a second direction y. Each first stripe structure 10 includes a first translucent strip 101 and a first opaque strip 102 adjacent to each other along the second direction y. The first direction x intersects the second direction y. The widths of the first translucent strip 101 and / or the first opaque strip 102 vary according to a first preset rule. For example, in this embodiment, the first preset rule is that the width increases linearly from the center to both sides; that is, the widths of the first translucent strip 101 and the first opaque strip 102 at the center of the moiré alignment mark are the narrowest, and the widths increase linearly from the center to the upper and lower sides. The width of the first translucent strip 101 can be understood as the spacing between two adjacent second opaque strips 102, and the width of the first opaque strip 102 can be understood as the line width. In other embodiments, the structure of the gradient spacing and line width can take various variations, including but not limited to: the gradient form of the spacing or line width (linear increase or decrease, non-linear increase or decrease, non-monotonic change according to a preset function, etc.), and whether the spacing and / or line width on both sides of the center line are symmetrical. Therefore, each stripe structure includes multiple parallel lines, and the spacing and / or line width of the lines in each stripe structure are gradually varied.

[0027] It is understandable that to achieve the alignment of moiré fringes, two alignment marks need to be designed. Optionally, the moiré alignment marks include a first alignment mark and a second alignment mark. The first alignment mark and the second alignment mark generate moiré fringes when the third direction overlaps. The third direction is perpendicular to the plane where the first alignment mark is located. The extension direction of the first light-transmitting strip in the first alignment mark and the extension direction of the first light-transmitting strip in the second alignment mark have a preset angle.

[0028] For example, Figure 3 This is a schematic diagram of a second alignment mark provided in an embodiment of the present invention. Figure 4 for Figure 2 The first alignment mark and Figure 3 A schematic diagram of the moiré fringes generated by the second alignment mark, see reference. Figure 2 and Figure 3 The extension direction of the first light-transmitting strip in the first alignment mark and the extension direction of the first light-transmitting strip in the second alignment mark have a preset angle (e.g., less than 45°), that is, there is a relative rotation of less than 45° between the two stripe structures (the angle between the midlines of the two stripe structures), so that a pattern can be formed on their common imaging plane. Figure 4 The moiré fringes shown are typically imaged on the detector's photosensitive plane. This rotation ensures the moiré fringes have a unique center point, eliminating periodic blurring and removing the need for coarse alignment markers.

[0029] In this embodiment, it is illustrated that the stripe structure in the first alignment mark and the second alignment mark follows the same pattern of change. In other embodiments, the stripe structure in the first alignment mark and the second alignment mark may also be designed to follow different patterns of change. Optionally, the stripe structure in the first alignment mark and the second alignment mark may have the same distribution pattern, or at least one of the distribution patterns of the light-transmitting or non-light-transmitting stripes in the first alignment mark and the second alignment mark may be different.

[0030] in addition, Figure 2 and Figure 3 The slatted stripe structure shown is only illustrative; in another embodiment, it can be designed... Figure 2 The middle stripe structure extends in the horizontal direction. Figure 3 The striped structure is tilted, and the design can be tailored to the specific implementation.

[0031] Understandable, Figure 4 The diagram illustrates moiré fringes in a non-ideal position (i.e., the first and second alignment marks are not aligned). In the ideal position, the geometric center of the image detector (i.e., the camera) or light intensity detector is set to coincide with the center point of the moiré fringes on the imaging plane. In this embodiment, the spacing and linewidth of the fringe structure gradually change from the center line to both sides, and therefore the period of its moiré fringes also gradually changes from the center line to both sides.

[0032] Figure 2 and Figure 3 The illustration shows a moiré alignment mark as a one-dimensional stripe structure. In other embodiments, the moiré alignment mark can also be designed as a two-dimensional stripe structure. Optionally, the moiré alignment mark further includes multiple second stripe structures extending along a second direction and arranged along a first direction. The second stripe structure includes a second light-transmitting strip and a second light-blocking strip arranged adjacent to each other along the first direction. The width of the second light-transmitting strip and / or the second light-blocking strip varies according to a second preset rule along the positive direction from the center of the moiré alignment mark to the first direction and along the negative direction from the center of the moiré alignment mark to the first direction.

[0033] For example, Figure 5 A schematic diagram of another first alignment mark provided in an embodiment of the present invention, see reference. Figure 5 The moiré alignment mark also includes multiple second stripe structures 20 extending along the second direction y and arranged along the first direction x. The second stripe structure 20 includes a second light-transmitting strip 201 and a second non-light-transmitting strip 202 arranged adjacent to each other along the first direction x. The widths of the second light-transmitting strip 201 and / or the second non-light-transmitting strip 202 along the positive direction from the center of the moiré alignment mark to the first direction and along the negative direction from the center of the moiré alignment mark to the first direction vary according to a second preset rule.

[0034] The second preset rule includes one of the following rules: linear increase, linear decrease, nonlinear increase, nonlinear decrease, or non-monotonic change according to the preset function rule. The specific implementation can be designed according to the actual situation.

[0035] The moiré alignment mark designed in this embodiment is changed from one-dimensional to two-dimensional. Its design method is similar to that of the previous embodiment, and will not be described in detail here.

[0036] Figure 6 This is a schematic diagram of another second alignment mark provided in an embodiment of the present invention. Figure 7 for Figure 5 The first alignment mark and Figure 6 A schematic diagram of the moiré fringes generated by the second alignment mark is shown in this embodiment. This embodiment provides a bidirectional fringe structure (each moiré alignment mark includes lines in two mutually perpendicular directions) as the moiré alignment mark. There is a small relative rotation angle between the first and second alignment marks, thus forming moiré fringes. It also includes a gradient spacing fringe structure in both the horizontal and vertical directions, thus achieving alignment in both directions simultaneously.

[0037] Based on the moiré alignment mark obtained by combining two of the above-mentioned fringe structures, the two fringe structures have relative rotation angles, thus giving the resulting moiré fringe a definite absolute center. By performing signal processing on the moiré fringe corresponding to the alignment mark, the error direction between the first and second alignment marks can be obtained, and it can be corrected to a predetermined ideal position, thereby achieving a self-referenced center positioning function. Moiré fringes have various applications (photolithography, precision machinery, optics, etc.), and can combine two sets of mutually angled fringes into a two-dimensional alignment mark.

[0038] Based on this, embodiments of the present invention provide an alignment device. Figure 8 This is a schematic diagram of an alignment device provided in an embodiment of the present invention, with reference to... Figure 8 The alignment device includes an illumination component 100, an alignment mark component 200, and a detection component 300. The alignment mark component 200 includes a first mark 210 and a second mark 220. The first mark 210 is located on the workpiece to be aligned. Figure 8 On (not shown), the second mark 220 is located on the workpiece (which serves as a reference). Figure 8 On (not shown), the first mark 210 and the second mark 220 are determined according to the moiré alignment marks provided in the above embodiment; the illumination component 100 is used to output an illumination beam, and the moiré fringes formed by the illumination beam after passing through the first mark 210 and the second mark 220 are incident on the detection component 300; the detection component 300 analyzes and calculates according to the detected moiré fringes, and moves the position of the workpiece to be aligned until the first mark 210 and the second mark 220 are aligned.

[0039] The illumination assembly 100 includes an illumination source 110 for outputting an illumination beam. In specific implementations, it also includes a workpiece stage for supporting and moving workpieces to be processed or used, such as masks, wafers, or chips. A first mark 210 is fabricated on the workpiece or on the workpiece stage. This embodiment of the invention uses a wafer as an example to illustrate the relevant content. The first mark 210 can be fabricated on the surface of the workpiece or workpiece stage, or on another specific layer of the workpiece or workpiece stage, ensuring that the illumination beam can irradiate the first mark 210. The alignment device operates as follows: During alignment, the illumination source 110 in the illumination assembly 100 emits a specific illumination beam (e.g., a beam with a specific wavelength or polarization). This beam is projected onto the first mark 210 on the workpiece to be aligned. After the illumination beam interacts with the first mark 210 (reflection, transmission, or diffraction), the return beam carrying wafer position information illuminates a preset reference reference—a second mark 220. Subsequently, the beam modulated by the second marker 220 carries the moiré fringes into the detection assembly 300 (e.g., a CMOS / CCD camera and processing unit, where the camera can be replaced by a light intensity detector). By analyzing and calculating the moiré fringes and moving the workpiece carrying the first marker 210, the workpiece is positioned in space as close as possible to the ideal position, thereby achieving precise alignment of the two moiré alignment markers.

[0040] Figure 9 This is a schematic diagram of another alignment device provided in an embodiment of the present invention, with reference to... Figure 9 The alignment device and Figure 8 The difference in the embodiment is that the first mark 210 remains unchanged, but the position of the second mark 220 changes. The second mark 220 is located between the lighting assembly 100 and the first mark 210. The illumination beam first illuminates the second mark 220 and then illuminates the first mark 210 after interacting with the second mark 220. The working process of this embodiment is as follows: the illumination source 110 in the lighting assembly 100 first projects onto the preset second mark 220. After the light interacts with the second mark 220, it illuminates the first mark 210 on the workpiece. Subsequently, the light beam modulated by the first mark 210 carries moiré fringes into the detection assembly 300. By analyzing and calculating the moiré fringes and moving the workpiece carrying the first mark 210, the position of the workpiece in space is made as close as possible to the ideal position, thereby achieving precise alignment of the two moiré alignment marks.

[0041] Continue to refer to Figure 8 or Figure 9Optionally, the detection component 300 includes a detector 310 and a processing unit 320. The detector 310 is used to receive moiré fringes, and the processing unit 320 is used to analyze and calculate based on the signal from the detector 310 and move the position of the workpiece to be aligned.

[0042] In one embodiment, optionally, the detector 310 includes a camera. The camera can acquire images of moiré fringes, and the processing unit 320 performs image processing to determine whether the first mark 210 and the second mark 220 are aligned based on the image processing results. For example, using... Figure 2 and Figure 3 The marking shown is an example (in other embodiments, it can also be used). Figure 5 and Figure 6 (as shown by the markings) Figure 10 This is a schematic diagram of the image after moiré fringe filtering. Figure 11 This is a schematic diagram of a binarized image. Figure 12 As shown in the schematic diagram of the image under ideal position, the processing unit 320 in the detection component 300 performs low-pass filtering, such as low-pass Gaussian filtering, on the moiré fringe image to filter out high-frequency noise in the image, resulting in... Figure 10 The filtered image shown includes low-frequency moiré fringes. Further binarization of this filtered image yields... Figure 11 The binarized image shown includes binarized moiré fringes. One of the moiré alignment markers is scanned along its alignment direction, causing horizontal displacement of the moiré fringes. Each position corresponds to a binarized moiré fringe image and an image similarity score. The position corresponding to the maximum value among all image similarities is taken as the target position. Then, the moiré alignment marker, such as the first marker, is moved from its current position to the target position, achieving alignment of the two moiré alignment markers. To obtain a moiré image at an ideal position, the two moiré alignment markers can be placed at predefined relative positions, and the geometric center of the detector can be moved to coincide with the center of the moiré image. The image is acquired by the detection component and then subjected to low-pass filtering, binarization, etc. Image comparison can be implemented using standard software algorithms (such as structural similarity algorithms, sum-of-squares algorithms, normalized cross-correlation algorithms, etc.). The technical solution of this embodiment has the advantages of good algorithmic flexibility and high degree of freedom in implementation.

[0043] In another embodiment, optionally, detector 310 includes an area array light intensity detector. Figure 13 This is a schematic diagram of a binary physical mask, in which a [structure / method] is used between the light intensity detector and the moiré alignment mark. Figure 13 The binarized physical mask shown filters the moiré fringes, and a light intensity detector detects the total light intensity value across the entire plane. One of the moiré alignment marks is scanned in the alignment direction so that the moiré fringes are horizontal (…). Figure 13The light intensity is generated in the horizontal direction. During the scanning process, the light intensity value measured by the overall light intensity sensor is collected. Each position corresponds to a moiré fringe image and a total light intensity value. The position corresponding to the maximum value among all total light intensity values ​​is taken as the target position. Then, the moiré alignment mark, such as the first mark, is moved from the current position to the target position to align the two moiré alignment marks. In the binary physical mask, white represents the transparent area and black represents the opaque area. This pattern is the moiré image at the ideal position, which can be obtained from previous experiments or simulations. The binary physical mask is a component with the same pattern processed based on the moiré image at the ideal position. Compared with the previous method, the detection scheme of this embodiment has the advantages of high sampling rate and fast measurement speed because it uses a light intensity detector.

[0044] In yet another embodiment, the detector 310 may optionally include a linear array light intensity detector.

[0045] For example, Figure 14 This is a schematic diagram of the distribution of a linear array optical intensity detector provided in an embodiment of the present invention, wherein... Figure 14 The center point marks the detector's position. Low-pass filtering, such as a low-pass Gaussian filter, is applied to the moiré fringes on the imaging plane. The detector employs at least two intensity detectors uniformly arranged along a vertical line passing through the center point. Figure 14 As shown by the dots. Figure 14 The diagram illustrates the relationship between the arrangement of the light intensity detectors and the moiré image under ideal positions. Compared to schemes using area array light intensity detectors, the light intensity detectors in this scheme can be arranged only in the vertical direction passing through the center point of the moiré fringes. One of the moiré alignment marks, such as the first pair, is scanned vertically, causing the moiré fringes to shift horizontally. During the scan, the sum of the light intensity values ​​measured by all light intensity detectors is collected, with each position corresponding to a moiré fringe image and a summed light intensity value. The position corresponding to the maximum value among all summed light intensity values ​​is taken as the target position. Then, the moiré alignment mark, such as the first alignment mark, is moved from the current position to the target position, as shown below. Figure 14 As shown. Compared to the two aforementioned schemes, the detection scheme in this embodiment has the advantages of not requiring the acquisition of moiré images at ideal locations, high sampling rate, and low cost. The three detection schemes provided in this embodiment of the invention all have the advantages of unique alignment center, no periodic blurring resulting in a large alignment range, and no need for coarse alignment compared to existing solutions.

[0046] For example, Figure 15 This is a schematic diagram of a wafer alignment device in a lithography machine provided in an embodiment of the present invention. Figure 15The diagram illustrates a workpiece stage and a wafer, with a second mark located on a photomask, which is mounted on a corresponding motion stage. The wafer alignment device operates as follows: During alignment, the illumination source 110 in the illumination assembly 100 emits a specific illumination beam (e.g., a beam with a specific wavelength or polarization). This beam is projected onto the second mark on the photomask. After the light interacts with the second mark (reflection, transmission, or diffraction), it illuminates the wafer (carrying the first mark), and a return beam carrying wafer position information illuminates the detection assembly 300. Subsequently, the beam modulated by the first mark, carrying moiré fringes, enters the detection assembly 300 (e.g., a CMOS / CCD camera and processing unit; the camera can be replaced by a light intensity detector). By analyzing and calculating the moiré fringes and moving the workpiece stage, the position of the first mark in space is made as close as possible to the ideal position, thereby achieving precise alignment of the two moiré alignment marks, and consequently, precise alignment of the wafer relative to the photomask in the lithography machine.

[0047] Figure 16 This is a schematic diagram of a precision alignment device for machined parts provided in an embodiment of the present invention. (Refer to...) Figure 16 This embodiment provides a workpiece alignment device based on a transmissive dual-marker. The alignment device includes, in sequence: an illumination assembly 100: located at the top of the device, containing an illumination source 110 for generating a vertically downward illumination beam; a workpiece 1 (with a second mark): mounted on a fixed platform. It has a pre-processed, light-transmitting second mark as described above, and its spatial position is fixed; a workpiece 2 (with a first mark): mounted on a movable platform. It has a pre-processed, light-transmitting first mark as described above, and its platform (moving platform) can be precisely adjusted in two directions; and a detection assembly 300: located at the bottom of the device, including a detector 310 (such as a CCD / CMOS camera) and a processing unit 320 for receiving the light beam transmitted through the marks on the two workpieces.

[0048] The working process is as follows: The light beam emitted by the illumination source 110 shines vertically downwards. The light beam first passes through the workpiece 1 on the fixed stage, and after passing through the workpiece 1, it continues to pass through the workpiece 2 on the moving stage, forming moiré fringes. Finally, the light beam carrying the moiré fringes enters the detection component 300 at the bottom. By analyzing and calculating the moiré fringes and moving the stage, the position of the first mark in space is made as close as possible to the ideal position, thereby achieving precise alignment between the workpieces.

[0049] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A moiré alignment mark, characterized in that, It includes multiple first stripe structures extending along a first direction and arranged along a second direction. The first stripe structure includes a first light-transmitting strip and a first non-light-transmitting strip arranged adjacent to each other along the second direction. The first direction intersects the second direction. The widths of the first light-transmitting strip and / or the first non-light-transmitting strip vary according to a first preset rule along the positive direction from the center of the moiré alignment mark to the second direction and along the negative direction from the center of the moiré alignment mark to the second direction.

2. The moiré alignment mark according to claim 1, characterized in that, It also includes multiple second stripe structures extending along the second direction and arranged along the first direction, wherein the second stripe structure includes a second light-transmitting strip and a second non-light-transmitting strip arranged adjacent to each other along the first direction; The widths of the second light-transmitting strip and / or the second non-light-transmitting strip vary according to a second preset rule along the positive direction from the center of the moiré alignment mark to the first direction and along the negative direction from the center of the moiré alignment mark to the first direction.

3. The moiré alignment mark according to claim 1 or 2, characterized in that, The moiré alignment mark includes a first alignment mark and a second alignment mark. The first alignment mark and the second alignment mark generate moiré fringes when they overlap in a third direction. The third direction is perpendicular to the plane where the first alignment mark is located. The extension direction of the first light-transmitting strip in the first alignment mark and the extension direction of the first light-transmitting strip in the second alignment mark have a preset angle.

4. The moiré alignment mark according to claim 3, characterized in that, The stripe structure distribution patterns in the first alignment mark and the second alignment mark are the same, or at least one of the distribution patterns of the light-transmitting or non-light-transmitting stripes in the stripe structure of the first alignment mark and the second alignment mark is different.

5. The moiré alignment mark according to claim 2, characterized in that, The first preset rule includes one of the following rules: linear increase, linear decrease, nonlinear increase, nonlinear decrease, or non-monotonic change according to the preset function rule; The second preset rule includes one of the following rules: linear increase, linear decrease, nonlinear increase, nonlinear decrease, or non-monotonic change according to the preset function rule.

6. An alignment device, characterized in that, It includes an illumination component, an alignment mark component, and a detection component. The alignment mark component includes a first mark and a second mark. The first mark is located on the workpiece to be aligned, and the second mark is located on the workpiece serving as a reference. The first mark and the second mark are determined by the Moiré alignment mark according to any one of claims 1 to 5. The illumination component is used to output an illumination beam, and the illumination beam, after passing through the first mark and the second mark, forms a moiré fringe that is incident on the detection component. The detection component analyzes and calculates based on the detected moiré fringes, and moves the position of the workpiece to be aligned until the first mark and the second mark are aligned.

7. The alignment device according to claim 6, characterized in that, The detection component includes a detector and a processing unit. The detector is used to receive the moiré fringes, and the processing unit is used to analyze and calculate based on the signal from the detector and move the position of the workpiece to be aligned.

8. The alignment device according to claim 7, characterized in that, The detector includes a camera.

9. The alignment device according to claim 7, characterized in that, The detector includes an area array light intensity detector.

10. The alignment device according to claim 7, characterized in that, The detector includes a linear array of light intensity detectors.

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