Overlay grating structure, method and device for measuring overlay error and storage medium

Abstract

The invention provides an overlay grating structure, a method and device for measuring an overlay error and a storage medium. The overlay grating structure comprises a first grating group, a second grating group and a first filling layer, the first grating group comprises a first grating with a first period and a second grating with a second period, and the second grating group comprises a third grating with the second period and a fourth grating with the first period; the second grating group is located right above the first grating group, the first filling layer is located between the first grating group and the second grating group, and the refractive index of the first filling layer is between the refractive index of air and the refractive index of the grating material. By adding the first filling layer in the first grating group and the second grating group, the transmission efficiency of light is remarkably improved, unnecessary reflection loss is reduced, and moire fringes with higher contrast can be formed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, and relates to a overlay grating structure, and a method, device and storage medium for measuring overlay error. BACKGROUND

[0002] Photoetching technology is the basis of large-scale integrated circuit manufacturing. In the photoetching process, overlay error is the main factor leading to processing defects. With the improvement of photoetching resolution, the alignment accuracy between multiple photoetching processes is required to be more and more strict.

[0003] In order to ensure the performance of semiconductor devices and the alignment accuracy between multiple photoetching processes, it is necessary to measure the overlay error. At present, the measurement methods of overlay error mainly include image-based overlay error measurement (IBO) and diffraction-based overlay error measurement (DBO). The IBO method is limited by the resolution of an optical microscope, and the focal length and the wavelength of the irradiation laser need to be adjusted constantly in the measurement process to improve the image contrast. The DBO method is more widely used, but the measurement result of the overlay error determined by the method has a large error. SUMMARY

[0004] The present application provides an overlay grating structure, and a method, device and storage medium for measuring overlay error, for improving the accuracy of overlay error measurement.

[0005] In a first aspect, the present application provides an overlay grating structure, which comprises a first grating group, a second grating group and a first filling layer; wherein the first grating group comprises a first grating with a first period and a second grating with a second period, the second grating group comprises a third grating with the second period and a fourth grating with the first period; the second grating group is located directly above the first grating group, and the first filling layer is located between the first grating group and the second grating group, wherein the first grating corresponds to the third grating, and the second grating corresponds to the fourth grating; wherein the refractive index of the first filling layer is between the refractive index of air and the refractive index of grating material.

[0006] In the present application, by adding a first filling layer in the first grating group and the second grating group, and the refractive index of the first filling layer is between the refractive index of air and the refractive index of grating material, more light can be transmitted into the first grating group, the transmission efficiency of light is significantly improved, unnecessary reflection loss is reduced, and two groups of moire fringes with higher contrast can be formed.

[0007] In a possible embodiment, the overlay grating structure further comprises a second filling layer, the second filling layer is located directly above the second grating group, wherein the refractive index of the second filling layer is the same as the refractive index of the first filling layer.

[0008] In the embodiment of the present application, the first filling layer is added between the first grating group and the second grating group, and the second filling layer is added above the second grating group, and the refractive index of the second filling layer is the same as the refractive index of the first filling layer, which further optimizes the coupling efficiency of light in the second grating group, so that the visibility of the Moiré fringe formed is higher, and the measurement precision of the overlay error is improved.

[0009] In a possible embodiment, the first filling layer is transparent, and the height of the first filling layer is 0.1 nm to 30 nm.

[0010] In the embodiment of the present application, the filling layer with a suitable thickness range is selected, which can optimize the interference effect of light and avoid excessive loss of light, and ensure the clarity and visibility of the Moiré fringe formed.

[0011] In a possible embodiment, the first grating group and the second grating group have the same total length and total width.

[0012] In the embodiment of the present application, the first grating group and the second grating group have the same total length and total width, which can maintain the consistency between the two groups of gratings and reduce the error introduced due to size mismatch.

[0013] In a possible embodiment, the height of each grating is 30 nm to 300 nm, the length of each grating is 30 nm to 500 nm, and the width of each grating is 10 nm to 200 nm.

[0014] In a possible embodiment, the grating material is silicon, the gap material of the grating is silicon dioxide, and the material of the first filling layer is silicon dioxide.

[0015] In a second aspect, the embodiment of the present application provides a method for measuring overlay error, the method comprising: acquiring images of two groups of Moiré fringes; the two groups of Moiré fringes are formed by vertical irradiation of the overlay grating structure by laser; the two groups of Moiré fringes comprise a first group of Moiré fringes associated with the first grating and the third grating in the overlay grating structure, and a second group of Moiré fringes associated with the second grating and the fourth grating in the overlay grating structure; and calculating the overlay error according to the images.

[0016] In the embodiment of the present application, the overlay error corresponding to the overlay grating structure can be obtained through the clear moire fringe image, and the measurement accuracy of the overlay error can be improved through the above method.

[0017] In a possible embodiment, calculating the overlay error according to the image comprises:

[0018] calculating a first difference value according to the image, the first difference value being a relative phase shift or a relative movement amount ΔX; wherein the relative phase shift The relative movement amount ΔX is determined according to a center position of a first bright fringe in the first set of moire fringes and a center position of a second bright fringe closest to the first bright fringe in the second set of moire fringes;

[0019] calculating the overlay error according to the first difference value, the first period and the second period.

[0020] In the embodiment of the present application, the first difference value can be determined by calculating a relative phase shift or a relative movement amount ΔX, two different methods are provided to measure the overlay error corresponding to the overlay grating structure, and the measurement accuracy and reliability are improved.

[0021] In a possible embodiment, the first difference value is a relative phase shift calculating the overlay error according to the first difference value, the first period and the second period adopts the following formula:

[0022]

[0023] wherein Δx is the overlay error, is the first difference value, P1 is the first period, and P2 is the second period.

[0024] In a possible embodiment, the first difference value is a relative movement amount ΔX; calculating the overlay error according to the first difference value, the first period and the second period adopts the following formula:

[0025] Δx=ΔX×(P2-P1) / (P1+P2);

[0026] wherein Δx is the overlay error, ΔX is the first difference value, P1 is the first period, and P2 is the second period.

[0027] In a third aspect, the present application provides a communication apparatus, which can execute the method / operation / step / action described in the second aspect or any one of the embodiments.

[0028] In a fourth aspect, the present application provides a computer storage medium, which stores a software program, and when the software program is read and executed by one or more processors, the method described in any one of the second aspect can be implemented.

[0029] On the basis of the implementation of the above aspects, the present application can be further combined to provide more implementations. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the implementation in the related art, the drawings needed in the following embodiment or related technology description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art according to these drawings.

[0031] Figure 1A A schematic diagram of a lower grating structure of a overlay grating structure is provided for the embodiments of the present application;

[0032] Figure 1B A schematic diagram of an upper grating structure of a overlay grating structure is provided for the embodiments of the present application;

[0033] Figure 2 A schematic diagram of a cross-sectional structure of a overlay grating structure is provided for the embodiments of the present application;

[0034] Figure 3A A schematic diagram of a overlay grating structure is provided for the embodiments of the present application;

[0035] Figure 3B A schematic diagram of a overlay grating structure is provided for the embodiments of the present application; Figure Two

[0036] Figure 4 A flowchart of a method for measuring overlay error is provided for the embodiments of the present application;

[0037] Figure 5 A schematic diagram of a structure for calculating the relative movement amount of moire fringes is provided for the embodiments of the present application. DETAILED DESCRIPTION

[0038] ​In order to make the purposes, technical solutions and advantages of the present application clearer, the following further describes the present application with reference to the accompanying drawings. Obviously, the embodiments described in the present application are only a part of the embodiments of the present application, and not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0039] It should be noted that the brief description of the terms in the present application is only for the convenience of understanding the subsequently described embodiments, and is not intended to limit the embodiments of the present application. Unless otherwise specified, these terms should be understood according to their ordinary and general meanings.

[0040] The terms "first", "second", "third", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar or similar objects or entities, and do not necessarily mean a specific order or sequence, unless otherwise noted. It should be understood that the terms used in this way can be interchanged under appropriate circumstances.

[0041] The terms "include" and "have" and any variations thereof are intended to cover but not exclusive inclusion, for example, a product or device including a series of components does not have to be limited to all components clearly listed, but can include other components not clearly listed or inherent to these products or devices.

[0042] Before introducing the method for measuring overlay error provided by the embodiments of the present application, in order to facilitate understanding, first, the technical background of the embodiments of the present application is introduced.

[0043] Grating: an optical element composed of many equally spaced fine parallel slits or lines, the main function of the grating is to decompose the incident light into different wavelengths of light spectrum through diffraction and interference effect, so as to realize the separation or diffraction of light.

[0044] Overlay error: refers to the error caused by the misalignment between different lithography layers in the semiconductor manufacturing process. In semiconductor chip manufacturing, multiple layers of lithography are usually required, and each layer must be accurately aligned with the previous pattern. If the alignment between these layers is not accurate, overlay error will occur. With the increase of the number of integrated circuits and the improvement of complexity, overlay error is a key parameter in the lithography process, and its control is crucial to ensure the normal operation of integrated circuits. By using advanced measurement and control methods, overlay error can be effectively reduced, and the performance and reliability of semiconductor devices can be improved.

[0045] Moire fringes: are the basis of precision measurement of grating displacement, in practical applications by two spatial frequency close to the periodic grating pattern superimposed optical fringes is the moire fringe, can be produced by the light shielding effect, diffraction effect and interference effect and other principles. Moire fringes are widely used in various fields, including optical measurement, interferometer and precision detection in semiconductor manufacturing, etc.

[0046] The present application provides a kind of overlay grating structure, overlay grating structure includes first grating group, second grating group and first filling layer.

[0047] Wherein, first grating group includes the first grating with first period, the second grating with second period, second grating group includes the third grating with second period, the fourth grating with first period;Second grating group is located in the positive above of first grating group, and first filling layer is located between first grating group and second grating group, wherein, first grating corresponds with third grating, and second grating corresponds with fourth grating;Wherein, the refractive index of first filling layer is between the refractive index of air and the refractive index of grating material.

[0048] The specific manufacturing process of overlay grating structure is introduced below. In the manufacturing process, the overlay grating structure is manufactured on the semiconductor material by using a photoetching machine. The present application does not limit the specific semiconductor material, for example, the semiconductor material can be a silicon wafer.

[0049] First, the first grating group is manufactured. The first grating group is composed of the first grating and the second grating. The period of the first grating is the first period, and the period of the second grating is the second period. The first period and the second period are slightly different, for example, the first period is 3 μm, and the second period is 3.5 μm. As shown in FIG. 1, the length of the first grating is the same as the length of the second grating, and the width can also be the same. They are located on the same plane to form the first grating group. Figure 1A

[0050] Secondly, the first filling layer is manufactured. The first filling layer is located above the first grating group. The first filling layer is transparent, with a height of 0.1 nm to 30 nm, and the refractive index is between the refractive index of air and the refractive index of grating material.

[0051] Thirdly, the second grating group is manufactured. The second grating group is composed of the third grating and the fourth grating, and the second grating is located above the first filling layer. As shown in FIG. 2, the length of the third grating is the same as the length of the fourth grating, and the width can also be the same. They are located on the same plane to form the second grating group. Figure 1B

[0052] Wherein, the second grating in the first grating layer corresponds to the fourth grating of the second grating layer, that is, the first grating overlaps the third grating, and the second grating overlaps the fourth grating. ​​

[0053] Furthermore, the first grating, the second grating, the third grating, and the fourth grating can have the same size.

[0054] For example, in the first grating group and the second grating group, the height of each grating is limited to 30 nm to 300 nm, the length of each grating is limited to 30 nm to 500 nm, and the width of each grating is limited to 10 nm to 200 nm. It is understood that the above values ​​are merely examples and are not intended to limit the scope of this application.

[0055] For example, the grating material can be Si, the gap material of the grating is SiO2, and the gap material is transparent; the filling layer material is SiO2.

[0056] Furthermore, the material of the grating and the gap material of the grating can be replaced with other materials, and this application does not limit this.

[0057] In addition, in one possible design, the overlay grating structure also includes a second filling layer, which is located directly above the second grating group. The second filling layer is transparent, has a height of 0.1 nm to 30 nm, and has the same refractive index as the first filling layer.

[0058] like Figure 2 The diagram shows a cross-sectional view of an overlay grating structure. The lower half corresponds to the first grating group and the first filling layer, while the upper half corresponds to the second grating group and the second filling layer. Both the first and second grating groups consist of many gratings and gaps arranged at equal intervals. The gratings correspond to the black parts, and the gaps in the gratings correspond to the white parts between adjacent black parts. The material of the filling layer can be the same as the material of the gaps in the gratings.

[0059] For example, such as Figure 3A and Figure 3B As shown, schematic diagrams of two overlay grating structures are provided. Figure 3A The overlay grating structure shown includes four layers, from bottom to top: semiconductor material, first grating layer, first filling layer, and second grating layer, wherein, combined with Figure 1A and Figure 1B The first grating in the first grating layer corresponds to the third grating in the second grating layer, and the second grating in the first grating layer corresponds to the fourth grating in the second grating layer. That is, the first grating overlaps with the third grating, and the second grating overlaps with the fourth grating.

[0060] Figure 3BThe grating structure shown includes five layers, from bottom to top: semiconductor material, first grating layer, first filling layer, second grating layer and second filling layer. The first grating in the first grating layer corresponds to the third grating in the second grating layer, and the second grating in the first grating layer corresponds to the fourth grating in the second grating layer. That is, the first grating overlaps with the third grating, and the second grating overlaps with the fourth grating.

[0061] For example, in the two overlay grating structures mentioned above, the first period corresponding to the first grating and the fourth grating is set to 2 μm, the second period corresponding to the second grating and the third grating is set to 2.2 μm, the height of the first grating group and the height of the second grating group are 100 nm, the height of the first filling layer is 20 nm, and the height of the second filling layer is 10 nm.

[0062] To improve the accuracy of overlay error measurement, such as Figure 4 As shown in the figure, an embodiment of the present invention provides a method for measuring overlay error, the method specifically including:

[0063] Step 400: Acquire images of two sets of moiré fringes.

[0064] Two sets of moiré fringes are formed by vertically irradiating a laser onto an overlay grating structure.

[0065] After fabricating the overlay grating structure, a laser is used to vertically illuminate the entire overlay grating structure from top to bottom, forming two sets of moiré fringes. The specific process is as follows:

[0066] Combination Figure 3A When the laser beam sequentially enters the second grating group and the first filling layer, upon reaching the first grating group, the beam undergoes m-order diffraction. When the m-order diffracted light reaches the second grating group, it undergoes n-order diffraction. When the m-order diffracted light from the first grating group and the n-order diffracted light from the second grating group superimpose, their phase difference forms two sets of moiré fringes above the overlay grating structure. The 0th order diffraction corresponds to the original incident light direction, while the m-order and n-order diffraction represent angular deviations on either side of the 0th order, with m and n being integers, typically ranging from -1 to 3.

[0067] When light propagates between different media, it undergoes reflection and transmission. The greater the difference in refractive index, the more light is reflected. By adding a first filling layer between the first and second grating groups, and ensuring that the refractive index of the first filling layer is between that of air and the grating material, the reflection loss of light on different gratings can be effectively reduced, and the light transmittance can be enhanced. This allows more light to be transmitted to the first grating group and reflected back, resulting in clearer and easier-to-observe moiré fringes in the two sets formed.

[0068] Furthermore, combined Figure 3BA second filling layer is added above the second grating group of the overlayed grating structure, and the refractive index of the second filling layer is the same as that of the first filling layer. On the basis of the above effects, the coupling efficiency of light in the second grating group can be further optimized, and the reflection loss of light in the second grating group is reduced, so that the visibility of the two groups of Moiré fringes formed above the overlayed grating structure is further improved, which is more conducive to subsequent image acquisition and observation.

[0069] The two groups of Moiré fringes include a first group of Moiré fringes associated with the first grating and the third grating, and a second group of Moiré fringes associated with the second grating and the fourth grating.

[0070] Specifically, when laser irradiates on the overlayed grating structure, due to the mutual overlap and the difference in period between the first grating and the third grating and between the second grating and the fourth grating, the reflected and transmitted light is diffracted to form multiple diffraction orders, and the light of different diffraction orders interferes in space to form two groups of Moiré fringes. When the diffracted light of the first grating and the third grating is superimposed, the phase difference generated forms the first group of Moiré fringes. Similarly, when the diffracted light of the second grating and the fourth grating is superimposed, the second group of Moiré fringes is formed.

[0071] The Moiré fringes include two kinds of fringes with light and dark interlaced. When the diffracted light from the first grating group and the diffracted light from the second grating group meet in space and the phases are consistent, constructive interference occurs, resulting in the strengthening of the intensity of the light, which appears as bright fringes, i.e. bright fringes. When the diffracted light from the first grating group and the diffracted light from the second grating group meet in space and the phases are opposite, destructive interference occurs, resulting in the weakening of the intensity of the light, which appears as dark fringes, i.e. dark fringes.

[0072] In a specific implementation, a suitable imaging device is selected to perform image acquisition on the two groups of Moiré fringes to form an image including the two groups of Moiré fringes.

[0073] The period of the Moiré fringe image can be calculated according to the first period and the second period, and whether the period of the Moiré fringe in the image is the same as the calculated period can be compared.

[0074] For example, the period of the Moiré fringe can be calculated by using the following formula 1:

[0075] P F =P1P2 / (P2-P1) (Formula 1);

[0076] P F is the period of the image, P1 is the first period, and P2 is the second period.

[0077] The formula shows the relationship between the period of the moire fringe and the period of the grating, i.e. the period of the moire fringe is much larger than the period of the grating (the first period and the second period) in the overlay grating structure, even if the period of the grating is very small, when the first period and the second period are subtracted, the period of the moire fringe will be relatively large, which makes it easier to observe and measure the formed moire fringe. In addition, the amplitude distribution of the moire fringe can be extracted from the collected image, and compared with the calculated amplitude distribution.

[0078] wherein the amplitude distribution of the moire fringe is calculated according to the first period, the second period, the Fourier coefficient of the first grating group occurring n-order diffraction and the Fourier coefficient of the second grating occurring -n-order diffraction, and specifically, the following formula 2 can be used:

[0079]

[0080] wherein A n is the Fourier coefficient of the first grating group occurring n-order diffraction, B -n is the Fourier coefficient of the second grating occurring -n-order diffraction, P1 is the first period, P2 is the second period, and x and y represent the coordinates of the moire fringe.

[0081] Step 410: calculating the overlay error according to the image.

[0082] Exemplarily, in the implementation process of calculating the overlay error according to the image, first, a first difference value is calculated according to the image, the first difference value is a relative phase shift or a relative movement amount ΔX, and the overlay error is calculated according to the first difference value, the first period and the second period.

[0083] wherein the relative phase shift is determined according to the phase parameter of the first group of moire fringes and the phase parameter of the second group of moire fringes. Specifically, the image containing the two groups of moire fringes is converted from the spatial domain to the frequency domain through Fourier transform, and the phase parameters of the two groups of moire fringes are extracted therefrom respectively, and the relative phase shift

[0084] Further, if the first difference value is a relative phase shift The overlay error is calculated according to the first difference value, the first period and the second period, and specifically, it can be shown as formula 3:

[0085]

[0086] wherein Δx is the overlay error, is the first difference value, P1 is the first period, and P2 is the second period.

[0087] The relative movement amount ΔX is determined according to the center position of the first bright fringe in the first set of Moire fringes and the center position of the second bright fringe closest to the first bright fringe in the second set of Moire fringes. Specifically, the center position of the first bright fringe in the first set of Moire fringes is determined by an image algorithm, and in the second set of Moire fringes, the second bright fringe closest to the first bright fringe in the first set of Moire fringes is found, and the center position thereof is determined. The center positions of the detected first bright fringe and second bright fringe are marked on the image, and the horizontal distance between the two center points is measured as the relative movement amount ΔX.

[0088] Exemplarily, as shown in the figure, Figure 5 The figure includes two sets of Moire fringes, assuming that the upper half corresponds to the second set of Moire fringes and the lower half corresponds to the first set of Moire fringes, wherein the white oval part corresponds to the bright fringe and the black oval part corresponds to the dark fringe. The center position of the first bright fringe of the first set of Moire fringes and the center position of the second bright fringe closest to the first bright fringe in the second set of Moire fringes are selected and marked. By measuring the horizontal distance between the two center positions, the relative movement amount ΔX of the image can be obtained. In addition, the relative movement amount ΔX can also be calculated according to the center position of the dark fringe of the first set of Moire fringes and the center position of the dark fringe closest to the dark fringe in the second set of Moire fringes. The measurement process is the same as the above process.

[0089] Further, if the first difference is the relative movement amount ΔX, the overlay error is calculated according to the first difference, the first period and the second period. Specifically, it can be shown as formula 4:

[0090] Δx = ΔX × (P2-P1) / (P1+P2) (Formula 4);

[0091] Where Δx is the overlay error, ΔX is the first difference, P1 is the first period, and P2 is the second period.

[0092] Further, the obtained overlay error can be compared with the simulation result, and the error obtained by comparison is close to the simulation result, which verifies the effectiveness and accuracy of the measurement method and effectively improves the measurement precision.

[0093] In summary, the present application adds a first filling layer between the first grating group and the second grating group, and the refractive index of the filling layer is between the refractive index of air and the refractive index of the grating material, so that more light is transmitted into the lower grating structure, the transmission efficiency of light is significantly improved, the reflection loss of light between the first grating group and the second grating group is effectively reduced, and the Moiré fringe with higher contrast and clarity is formed; further, by adding a second filling layer above the second grating group, the coupling efficiency of light in the second grating group is further optimized, so that the formed Moiré fringe has higher visibility, and more accurate image data is provided for image acquisition and calculation of overlay error; in addition, by forming a more obvious Moiré fringe image, more accurate phase information is provided, the measurement accuracy is improved, and defects caused by inaccurate alignment are reduced, thereby effectively improving the production efficiency and performance of semiconductor devices.

[0094] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A grating structure, characterized in that, The overlay grating structure includes a first grating group, a second grating group, and a first filling layer; wherein, the first grating group includes a first grating with a first period and a second grating with a second period, the second grating group includes a third grating with a second period and a fourth grating with a first period; the second grating group is located directly above the first grating group, and the first filling layer is located between the first grating group and the second grating group; Wherein, the first grating corresponds to the third grating, and the second grating corresponds to the fourth grating; wherein, the refractive index of the first filling layer is between the refractive index of air and the refractive index of the grating material.

2. The overlay grating structure as described in claim 1, characterized in that, The overlay grating structure further includes a second filling layer, which is located directly above the second grating group, wherein the refractive index of the second filling layer is the same as that of the first filling layer.

3. The overlay grating structure as described in claim 1, characterized in that, The first filling layer is transparent, and the height of the first filling layer is 0.1nm to 30nm.

4. The overlay grating structure as described in claim 1, characterized in that, The first grating group and the second grating group have the same total length and total width.

5. The overlay grating structure as described in claim 1, characterized in that, The height of each grating is 30nm to 300nm, the length of each grating is 30nm to 500nm, and the width of each grating is 10nm to 200nm.

6. The overlay grating structure as described in claim 1, characterized in that, The grating material is silicon; The gap material of the grating is silicon dioxide; The material of the first filling layer is silicon dioxide.

7. A method for measuring overlay error, characterized in that, The method, applicable to the overlay grating structure as described in any one of claims 1 to 6, comprises: Images of two sets of moiré fringes are acquired; the two sets of moiré fringes are formed by vertically irradiating the overlay grating structure with a laser; the two sets of moiré fringes include: a first set of moiré fringes associated with the first grating and the third grating in the overlay grating structure, and a second set of moiré fringes associated with the second grating and the fourth grating in the overlay grating structure; The overlay error is calculated based on the image.

8. The method as described in claim 7, characterized in that, The calculation of overlay error based on the image includes: A first difference is calculated based on the image, the first difference being the relative phase shift. Or the relative shift ΔX; wherein, the relative phase shift The relative movement ΔX is determined based on the phase parameters of the first set of moiré fringes and the phase parameters of the second set of moiré fringes. The relative movement ΔX is determined based on the center position of the first bright fringe in the first set of moiré fringes and the center position of the second bright fringe in the second set of moiré fringes that is closest to the first bright fringe. The overlay error is calculated based on the first difference, the first period, and the second period.

9. The method as described in claim 8, characterized in that, The first difference is the relative phase shift. The overlay error is calculated based on the first difference, the first period, and the second period using the following formula: Wherein, Δx is the overlay error. P1 is the first difference, P2 is the first period, and P2 is the second period.

10. The method as described in claim 8, characterized in that, The first difference is the relative movement ΔX; The overlay error is calculated based on the first difference, the first period, and the second period using the following formula: Δx = ΔX × (P2 - P1) / (P1 + P2); Wherein, Δx is the overlay error, ΔX is the first difference, P1 is the first period, and P2 is the second period.

11. A device for measuring overlay error, characterized in that, It includes units or modules for performing the method as described in any one of claims 7 to 10.

12. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, the computer program including program instructions that, when executed by a computer, cause the computer to perform the method as described in any one of claims 7 to 10.

Images