Multi-wavelength stacked gate stripe array mark aligning and leveling system and method

Abstract

The invention discloses a multi-wavelength stacked gate stripe array mark alignment leveling system and method. The system comprises a scanning motion table, a mask table, a laser light source, a coupler, a collimation beam expander, a mask alignment mark grating, a substrate alignment mark grating, a beam splitter prism and a camera. The laser light source controls to emit a parallel light source, light beam coupling is carried out through the coupler, the size of an incident light spot is adjusted through the collimation beam expander, and then the light vertically enters the mask alignment mark grating to be diffracted; diffracted light passing through the mask alignment mark grating is diffracted and reflected again on the substrate alignment mark grating, all levels of sub-harmonics modulated by the third grating are subjected to Moire interference and then are received by the objective lens, and Moire interference fringes are recorded by the camera; the combined multi-wavelength light source performs superposition integration on different wavebands according to a weight proportion; the received moire fringe image is preprocessed, then phase extraction and analysis are carried out, and finally the alignment offset is calculated.

Description

Technical Field

[0001] The embodiments of the present invention relate to photolithography technology, and in particular to a multi-wavelength stacked moiré fringe array mark alignment and leveling system and method. Background Art

[0002] As the most critical process in the production and manufacturing of large-scale integrated circuits, photolithography is a technology that uses lasers to image mask patterns onto substrates such as substrates. The production of a chip requires hundreds of exposures. The deviation between the pattern of the current layer and the pattern of the reference layer in the last exposure is called overlay error. According to the forecast of (IRDS), by 2023, the requirement for overlay error in chip manufacturing will be less than 2 nanometers, which poses a huge challenge to the alignment system.

[0003] The current mainstream alignment methods include alignment measurement methods based on geometric patterns, alignment methods based on light intensity signal analysis, alignment measurement methods based on zone plates, alignment measurement methods based on grating diffraction interferometry, and alignment measurement methods based on moiré fringes.

[0004] Traditional moiré fringe alignment methods are all based on image processing methods, which have large computational complexity, low alignment accuracy, and difficulty in handling rotation errors introduced by the deflection of alignment marks. Since the formation of moiré interference fringes is limited by the Talbot principle, the alignment process must accurately control the spacing between mask marks and substrate marks, which greatly reduces the adaptability of the lithography process. Therefore, a lithography alignment method is urgently needed to expand the limitations of moiré interference fringe alignment on gap control. Summary of the invention

[0005] The object of the present invention is to provide a multi-wavelength moire fringe array mark alignment and leveling system and method for monitoring the tilt between a substrate and a mask and the position deviation between a substrate pattern and a mask pattern.

[0006] The present invention uses a multi-wavelength light source to pass through the mask alignment mark grating. The multi-wavelength can form an ultra-long Talbot distance behind the mask alignment mark grating. When the substrate alignment mark is located in this Talbot distance, clear moiré fringe imaging can be obtained, thereby extending the distance between the substrate and the mask and improving the process adaptability. In order to solve the problem of the analytical accuracy of the offset between the mask and the substrate, the method of image filtering, solving the average value, and rotation angle compensation is used to reduce the introduced error and improve the alignment accuracy.

[0007] The technical solution of the present invention is: a multi-wavelength stacked moire stripe array mark alignment and leveling system, comprising a workpiece stage, a scanning motion stage, an alignment and leveling detection system, a mask, a substrate, and a workpiece stage, wherein the alignment and leveling detection system comprises an imaging system, wherein the imaging system comprises a beam splitter prism, an objective lens group, and a CCD camera, and the alignment and leveling detection system further comprises: a mask stage, a first laser light source, a second laser light source, a third laser light source, a fourth laser light source, a coupler, and a collimating beam expander; the first, second, third, and fourth mask alignment marks and the first, second, third, and fourth substrate alignment marks are respectively located on the mask and the substrate, the scanning motion stage is at the top of the system, and there are two alignment and leveling detection systems on the left and right, the two have the same structure but different positions, and the imaging system is connected by screws Fixed on the scanning motion table, the positions of the two imaging systems are symmetrical with respect to the central axis of the motion scanning table. Four laser light sources, couplers and collimating beam expanders are connected to the side of the scanning motion table through optical fibers and incident on the beam splitter prism of the imaging system. Below the beam splitter prism of the imaging system are the mask table and the workpiece table. The substrate is placed on the upper surface of the workpiece table, and the mask is placed on the mask table above the substrate. The laser light source enters the imaging system through the coupler and the collimating beam expander, and is incident on the mask alignment mark grating through the beam splitter prism to diffract with the substrate alignment mark grating. The reflected light enters the objective lens group again to form an image at the CCD camera. By performing phase extraction and analysis on the fringe image received by the CCD camera, the offset is derived to achieve compensation for the alignment position deviation.

[0008] The beneficial effects of the present invention are:

[0009] The structure is simple and clear. Compared with the traditional moiré interference fringe alignment technology, the reflective device used in the present invention improves the integration of the equipment and reduces the space occupancy rate of the equipment. The use of multiple wavelength lasers for coupling increases the available focal depth range between the mask alignment mark grating and the substrate alignment mark grating, while significantly enhancing the signal strength of the moiré interference fringes. The practicality of the present invention is extremely high. When applied in the field of near-field lithography alignment, there is no need to add additional components. Only the type of light source needs to be replaced to effectively relax the gap limit between the mask alignment grating and the substrate alignment grating, greatly improving the applicability and flexibility of near-field lithography alignment technology. In the precise alignment part, the error introduced by the rotation angle of the image is taken into account and compensated, and the error introduced by noise and defects is taken into account and compensated, which greatly improves the alignment accuracy between the substrate and the mask. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The specific structural form of the multi-wavelength moiré fringe array mark alignment and leveling method described in the present invention is further described in the form of the attached drawings:

[0011] Figure 1 A structural diagram of a multi-wavelength moiré fringe array marking alignment and leveling system provided by the present invention;

[0012] Figure 2 A distribution map of mask alignment marks on the mask plate;

[0013] Figure 3 A distribution map of substrate alignment marks on a substrate;

[0014] Figure 4 A grating structure diagram for mask alignment marks;

[0015] Figure 5 A grating structure diagram for substrate alignment mark;

[0016] Figure 6 Flowchart for substrate leveling and alignment;

[0017] Figure 7 This is the flow chart of the alignment signal processing.

[0018] In the figure, the reference numerals are: 1.1-left side alignment and leveling detection system, 1.2-right side alignment and leveling detection system, 2-imaging system, 3-scanning motion stage, 4-mask stage, 5-mask plate, 6-substrate, 7-workpiece stage, 8-first laser light source, 9-second laser light source, 10-third laser light source, 11-fourth laser light source, 12-coupler, 13-collimation beam expander, 14-beam splitter prism, 15-objective lens group, 16-CCD camera, 171-first mask alignment mark, 172-second mask alignment mark, 173-third mask alignment mark, 174-fourth mask alignment mark, 181-first substrate alignment mark, 182-second substrate alignment mark, 183-third substrate alignment mark, 184-fourth substrate alignment mark, 191-mask first X direction fine alignment mark upper grating, 192-mask first X direction fine alignment mark lower grating, 20 1-left grating of the first Y direction precision alignment mark of the mask, 202-right grating of the first Y direction precision alignment mark of the mask, 211-upper grating of the second X direction precision alignment mark of the mask, 212-lower grating of the second X direction precision alignment mark of the mask, 221-left grating of the second Y direction precision alignment mark of the mask, 222-right grating of the second Y direction precision alignment mark of the mask, 231-coarse alignment mark of the mask, 193-upper grating of the first X direction precision alignment mark of the substrate, 194-lower grating of the first X direction precision alignment mark of the substrate, 203-left grating of the first Y direction precision alignment mark of the substrate, 204-right grating of the first Y direction precision alignment mark of the substrate, 213-upper grating of the second X direction precision alignment mark of the substrate, 214-lower grating of the second X direction precision alignment mark of the substrate, 223-left grating of the second Y direction precision alignment mark of the substrate, 224-right grating of the second Y direction precision alignment mark of the substrate, 232-coarse alignment mark of the substrate. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above-mentioned purpose, the present invention adopts the following technical scheme.

[0020] like Figure 1 As shown, a multi-wavelength moiré stripe array mark alignment and leveling system comprises: a left alignment and leveling detection system 1.1, a right alignment and leveling detection system 1.2, a scanning motion stage 3, a mask 5, a substrate 6, and a workpiece stage 7, wherein one alignment and leveling detection system comprises: an imaging system 2, a mask stage 4, a first laser light source 8, a second laser light source 9, a third laser light source 10, a fourth laser light source 11, a coupler 12, and a collimating beam expander 13; the first, second, third, and fourth mask alignment marks 171, 172, 173, and 174 and the first, second, third, and fourth substrate alignment marks 181, 182, 183, and 184 are respectively located on the mask 5 and the substrate 6; the imaging system 2 comprises: a beam splitter prism 14, an objective lens group 15, and a CCD camera 16. The scanning motion stage 3 is at the top of the entire system, with a left-side alignment and leveling detection system 1.1 and a right-side alignment and leveling detection system 1.2 respectively arranged on the left and right sides. The left-side alignment and leveling detection system 1.1 and the right-side alignment and leveling detection system 1.2 have the same structure but different positions. The entire imaging system 2 is fixed to the scanning motion stage 3 by screws, and the positions of the two imaging systems 2 are symmetrical about the central axis of the scanning motion stage 3. The first laser light source 8, the second laser light source 9, the third laser light source 10, the fourth laser light source 11, the coupler 12 and the collimating beam expander 13 are connected to the side of the scanning motion stage 3 through optical fibers and are incident on the beam splitter prism 14 of the imaging system 2. A certain distance below the imaging system 2 is the mask stage 4 and the workpiece stage 7. The laser light source is controlled to emit a parallel light source, which is coupled by a coupler 12, and then the incident light spot size is adjusted by a collimating beam expander 13, and then vertically incident on the grating in the mask alignment mark of the mask plate 5 to cause diffraction; the diffracted light passing through the grating in the mask alignment mark is diffracted and reflected again at the alignment mark grating of the substrate 6, and the harmonics of each level after three grating modulation are received by the objective lens group 15 after Moire interference, and then the Moire interference fringes are recorded by the CCD camera 16; the multi-wavelength light source after beam combination enhances the light intensity of the Moire interference fringes by superimposing and integrating different bands according to the weight ratio, so as to expand the effective formation range of the Moire interference fringes; the received Moire fringe image is preprocessed, and then phase extraction and analysis are performed to finally solve the alignment offset, wherein the CCD camera 16 adopts a high-sensitivity CCD camera.

[0021] The parallel light source is four single-wavelength laser light sources that are combined into a parallel light source with adjustable light intensity and beam spot size through a coupler 12 and a collimating beam expander 13. The laser light source includes first, second, third, and fourth laser light sources 8, 9, 10, and 11. The magnification of the objective lens 15 can be adjusted from 2 to 9 times. The first, second, third, and fourth mask alignment marks 171, 172, 173, and 174 and the first, second, third, and fourth substrate alignment marks 181, 182, 183, and 184 are four-quadrant phase gratings made of quartz material as a base and covered with metal Cr.

[0022] like Figure 2 As shown, the mask alignment marks on the mask plate 5 are phase gratings made of quartz material, and are set to four, namely, a first mask alignment mark 171, a second mask alignment mark 172, a third mask alignment mark 173, and a fourth mask alignment mark 174.

[0023] like Figure 4 As shown, the first, second, third and fourth mask alignment marks 171, 172, 173 and 174 all include a mask coarse alignment mark 231 and four pairs of fine alignment marks: an upper grating 191 of a mask first X-direction fine alignment mark, a lower grating 192 of a mask first X-direction fine alignment mark, a left grating 201 of a mask first Y-direction fine alignment mark, a right grating 202 of a mask first Y-direction fine alignment mark, an upper grating 211 of a mask second X-direction fine alignment mark, a lower grating 212 of a mask second X-direction fine alignment mark, a left grating 221 of a mask second Y-direction fine alignment mark, and a right grating 222 of a mask second Y-direction fine alignment mark. The period of the upper grating is 4 um, and the period of the lower grating is 4.4 um.

[0024] like Figure 3 As shown, the substrate alignment mark on the substrate 6 is also a phase grating made of quartz material, and is set to four, namely, a first substrate alignment mark 181, a second substrate alignment mark 182, a third substrate alignment mark 183, and a fourth substrate alignment mark 184.

[0025] like Figure 5 As shown, the first, second, third and fourth substrate alignment marks 181, 182, 183 and 184 all include a substrate coarse alignment mark 232, and four pairs of fine alignment marks: an upper grating 193 of a substrate first X-direction fine alignment mark, a lower grating 194 of a substrate first X-direction fine alignment mark, a left grating 203 of a substrate first Y-direction fine alignment mark, a right grating 204 of a substrate first Y-direction fine alignment mark, an upper grating 213 of a substrate second X-direction fine alignment mark, a lower grating 214 of a substrate second X-direction fine alignment mark, a left grating 223 of a substrate second Y-direction fine alignment mark, and a right grating 224 of a substrate second Y-direction fine alignment mark. The period of the upper row gratings is 4.4 um, and the period of the lower row gratings is 4 um.

[0026] like Figure 6 As shown, a multi-wavelength moire fringe array mark alignment and leveling method of the present invention comprises the following steps:

[0027] Step 1: The light source after being combined by the coupler 12 and the collimating beam expander 13 is vertically incident on the mask alignment mark and the substrate alignment mark and then reflected back. The light after thrice-modulated enters the imaging system 2 and is captured by the CCD camera 16; by observing the mask coarse alignment mark 231 in the mask alignment mark of the CCD camera 16, it is roughly nested in the center of the substrate coarse alignment mark 232 in the substrate alignment mark, and the coarse alignment is completed;

[0028] Since the numerical aperture of the detection system is small, and the mask has the same diffraction order after the two diffraction orders with the same algebraic sum and the same diffraction order of the substrate have the same emission direction, the influence of the first diffraction of the mask is ignored, and only the effects of the substrate diffraction and the second diffraction of the mask are considered. The complex amplitude of the moiré fringe received by the CCD camera 16 can be simplified to the complex amplitude of the moiré fringe that occurs n times of diffraction at the grating in the substrate alignment mark and m times of diffraction at the grating in the mask alignment mark. The expression is as follows:

[0029] ,

[0030] Where, m is the diffraction order of the diffracted beam at the mask alignment mark grating;

[0031] n—the diffraction order of the diffracted light beam on the substrate alignment mark grating;

[0032] —the frequency of the alignment marks of the mask alignment mark grating, , is the period of the mask alignment mark;

[0033] —the frequency of the alignment marks of the mask alignment mark grating, , is the period of the substrate alignment mark;

[0034] (x,y)—represents the complex amplitude distribution in the xy coordinate system, represents the amplitude of the complex amplitude distribution;

[0035] Represents the phase information of the complex amplitude;

[0036] Due to the numerical aperture and light intensity of the system, only the most easily distinguishable (1, -1), (0, 0), (1, -1) moiré fringes formed on the CCD camera 16 are accepted and analyzed to obtain the relative offset between the mask and the substrate. The distance between the grating mark and the target surface of the CCD camera 16 is not constant. The z-direction distance expression is introduced into the complex amplitude of the moiré fringes as follows:

[0037] ,

[0038] In the formula, is the constant phase delay in the nonlinear phase factor;

[0039] z is the propagation distance of the light source along the z axis;

[0040] is the frequency-dependent phase shift in the nonlinear phase factor;

[0041] is the spatial frequency of the incident light field on the x-axis, , is the period of the mask alignment mark;

[0042] is the spatial frequency of the incident light field on the x-axis, , is the period of the substrate alignment mark;

[0043] Ignoring the constant phase delay in the nonlinear phase factor, the intensity of the moiré interference fringe signal is It can be expressed as:

[0044] ,

[0045] In the formula, is the spectral weight coefficient (the coefficient used to weight the light intensity of different bands in spectral analysis); is the wavelength; for conjugation of;

[0046] When the distance z satisfies the condition:

[0047] ,

[0048] When k=1, 2, etc., the moiré fringe image is clearest. It is called the Talbot distance. The depth of focus (DOF) is defined by the width of the bright field. The different wavelength spectra of the combined light are at the Talbot distance. The integral on can extend the focal depth, and the extended DOF is:

[0049] ,

[0050] Where N is the multiple of the Talbot distance to the substrate alignment mark grating after expansion;

[0051] Step 2: drive the scanning motion stage 3 to lift the workpiece stage 7 upward until the substrate 6 and the mask 5 are tightly attached to each other for a few seconds, and then return to the original position, thus completing the leveling;

[0052] Step 3: Observe the tilt angles of the first, second, third, and fourth mask alignment marks 171, 172, 173, and 174 relative to the first, second, third, and fourth substrate alignment marks 181, 182, 183, and 184 and make corrections;

[0053] Step 4: Flowchart as follows Figure 7 As shown, the recorded moiré interference fringe signal is converted into a digital image for precise alignment. The effective range is cropped by an image preprocessing algorithm, and the phase is analyzed by Fourier transform to calculate the phase difference of the moiré interference fringe, thereby adjusting the relative position relationship between the mask alignment mark and the substrate alignment mark;

[0054] Specifically, when the grating 191 on the mask first X-direction fine alignment mark in the first mask alignment mark 171 and the grating 193 on the substrate first X-direction fine alignment mark in the first substrate alignment mark 181 are offset When , the complex amplitude expression of the moiré fringe (here we take the (-1,1) level as an example) is:

[0055] ,

[0056] ,

[0057] in , is the grating frequency of the grating in the mask alignment mark and the grating in the substrate alignment mark,

[0058] The complex amplitude distribution of the moiré fringes formed by the superposition of the grating 191 on the mask first X-direction fine alignment mark in the first mask alignment mark 171 and the grating 193 on the substrate first X-direction fine alignment mark in the first substrate alignment mark 181;

[0059] The complex amplitude distribution of the moiré fringe formed by the superposition of the mask first X-direction fine alignment mark lower grating 192 in the first mask alignment mark 171 and the substrate first X-direction fine alignment mark lower grating 194 in the first substrate alignment mark 181;

[0060] The cycle is and The gratings together form a period of The moiré fringes of the two gratings are calculated by the phase difference between them:

[0061] ,

[0062] ,

[0063] ,

[0064] The offset between the mask and substrate alignment mark grating can be solved:

[0065] ,

[0066] Through this embodiment, the effects of extending the Talbot distance, adjusting the parallelism between the mask and the substrate, and calculating the offset between the mask and the substrate can be achieved.

[0067] The design examples described in detail in the present invention are only used to illustrate the advantages and rationality of the present invention. All examples optimized based on the technical solution of the present invention belong to the scope of the present invention. The technologies and principles not described in detail in the present invention are well known to people in the field of the present invention.

Claims

1. A multi-wavelength moiré fringe array marking alignment and leveling system, characterized in that: It includes a workpiece stage, a scanning motion stage, an alignment and leveling detection system, a mask, a substrate, and a workpiece stage. The alignment and leveling detection system includes an imaging system, wherein the imaging system includes a beam splitter, an objective lens group, and a CCD camera. The alignment and leveling detection system also includes: a mask stage, a first laser light source, a second laser light source, a third laser light source, a fourth laser light source, a coupler, and a collimating beam expander; the first, second, third, and fourth mask alignment marks and the first, second, third, and fourth substrate alignment marks are respectively located on the mask and the substrate, the scanning motion stage is at the top of the system, and there are two alignment and leveling detection systems on the left and right, which have the same structure but different positions. The imaging system is fixed to the scanning motion stage by screws. The position of the system is symmetrical to the left and right of the central axis of the moving scanning stage. Four laser light sources, couplers and collimating beam expanders are connected to the side of the scanning moving stage through optical fibers and are incident on the beam splitter prism of the imaging system. Below the beam splitter prism of the imaging system are the mask stage and the workpiece stage. The substrate is placed on the upper surface of the workpiece stage, and the mask is placed on the mask stage above the substrate. The laser light source enters the imaging system through the coupler and the collimating beam expander, and is incident on the mask alignment mark grating through the beam splitter prism, where it diffracts against the substrate alignment mark grating. The reflected light enters the objective lens group again to form an image at the CCD camera. By performing phase extraction and analysis on the fringe image received by the CCD camera, the offset is derived to achieve compensation for the alignment position deviation.

2. A multi-wavelength moiré fringe array mark alignment and leveling system according to claim 1, characterized in that: The laser light source is combined into a multi-wavelength light source with different weights in each band through a coupler; the collimating beam expander is used to control the parallelism of the light beam and the size of the beam spot; the substrate and mask alignment mark grating is a four-quadrant phase grating made of quartz glass; the objective lens group is an adjustable magnifying objective lens for receiving a third-diffracted light beam; the CCD camera is used to record the image formed by the third-diffracted light beam.

3. The multi-wavelength moiré fringe array mark alignment and leveling system according to claim 1, characterized in that: Place the substrate on the upper surface of the workpiece table and the mask on the mask table, first level it and then perform alignment operations.

4. The multi-wavelength moiré fringe array mark alignment and leveling system according to claim 1, characterized in that: The first, second, third and fourth mask alignment marks all include a mask coarse alignment mark and four pairs of fine alignment marks: an upper grating of the first X-direction fine alignment mark of the mask, a lower grating of the first X-direction fine alignment mark of the mask, a left grating of the first Y-direction fine alignment mark of the mask, a right grating of the first Y-direction fine alignment mark of the mask, an upper grating of the second X-direction fine alignment mark of the mask, a lower grating of the second X-direction fine alignment mark of the mask, a left grating of the second Y-direction fine alignment mark of the mask, and a right grating of the second Y-direction fine alignment mark of the mask. The period of the upper row grating is 4um, and the period of the lower row grating is 4.4um.

5. A multi-wavelength moiré fringe array mark alignment and leveling system according to claim 4, characterized in that: The first, second, third and fourth substrate alignment marks all include substrate coarse alignment marks and four pairs of fine alignment marks: an upper grating of a substrate first X-direction fine alignment mark, a lower grating of a substrate first X-direction fine alignment mark, a left grating of a substrate first Y-direction fine alignment mark, a right grating of a substrate first Y-direction fine alignment mark, an upper grating of a substrate second X-direction fine alignment mark, a lower grating of a substrate second X-direction fine alignment mark, a left grating of a substrate second Y-direction fine alignment mark, and a right grating of a substrate second Y-direction fine alignment mark. The period of the upper row grating is 4.4um, and the period of the lower row grating is 4um.

6. A method for aligning and leveling a multi-wavelength moiré fringe array mark, characterized in that: The following steps are involved: Step 1: The laser light source after beam combination by the coupler and collimator is vertically incident on the mask alignment mark grating and the substrate alignment mark grating and then reflected back. The light modulated three times enters the imaging system and is captured by the CCD camera; by observing the mask coarse alignment mark in the mask alignment mark of the CCD camera, it is nested in the center of the substrate coarse alignment mark of the substrate alignment mark, and the coarse alignment is completed; Step 2: Drive the motion stage to lift the workpiece stage upward until the substrate and the mask are tightly attached to each other for one second, and then return to their original positions to complete the leveling; Step 3: Correct the image Rz rotation. Here, the rotation correction refers to the rotation correction of the substrate relative to the mask. Step 4: Precise alignment of the mask and substrate; pre-process the image recorded by the CCD camera, including image filtering, image cropping, and image rotation correction, and then perform Fourier transform, extract phase information from the frequency domain, calculate the phase difference of the same position point of adjacent gratings after cropping, and then solve to obtain the offset to complete the alignment operation of the mask and substrate.

7. A method for aligning and leveling a multi-wavelength moiré fringe array mark according to claim 6, characterized in that: Step 4 is: the fine alignment step first performs spatial filtering on the image; then adjusts the image tilt angle; crops the effective part of the image and takes the average value along the X or Y direction; performs Fourier transform on the image to extract the image phase in the frequency domain; solves the alignment mark phase difference and converts it into alignment deviation.

8. A method for aligning and leveling a multi-wavelength moiré fringe array mark according to claim 7, characterized in that: Step 1 is as follows: The complex amplitude of the moiré fringe received by the CCD camera is simplified to the complex amplitude of the moiré fringe that the light source diffracts n times at the substrate alignment mark grating and m times at the mask alignment mark grating. The expression is as follows: ， Where, m is the diffraction order of the diffracted beam at the mask alignment mark grating; n—the diffraction order of the diffracted light beam on the substrate alignment mark grating; —the frequency of the alignment marks of the mask alignment mark grating, , is the period of the mask alignment mark; —the frequency of the alignment marks of the mask alignment mark grating, , is the period of the substrate alignment mark; (x,y)—represents the complex amplitude distribution in the xy coordinate system, represents the amplitude of the complex amplitude distribution; Represents the phase information of the complex amplitude; The expression of z-direction distance introduced into the complex amplitude of moiré fringe is as follows: ， In the formula, is the constant phase delay in the nonlinear phase factor; z is the propagation distance of the light source along the z axis; is the frequency-dependent phase shift in the nonlinear phase factor; is the spatial frequency of the incident light field on the x-axis, , is the period of the mask alignment mark grating; is the spatial frequency of the incident light field on the x-axis, , is the period of the substrate alignment mark grating; Ignoring the constant phase delay in the nonlinear phase factor, the intensity of the moiré interference fringe signal is It is expressed as: ， In the formula, is the spectral weight coefficient; is the wavelength; for conjugation of; When the distance z satisfies the condition: ， When k=1, 2, etc., the moiré fringe image is clearest. It is called the Talbot distance; the depth of focus is defined by the width of the bright field, and the different wavelength spectra of the combined beam are at the Talbot distance. The integrated extended focal depth on the , the extended focal depth is: ， Where N is the multiple of the expanded Talbot distance to the substrate alignment mark grating.

9. A method for aligning and leveling a multi-wavelength moiré fringe array mark according to claim 8, characterized in that: Step 4 is as follows: The recorded moiré interference fringe signals are converted into digital images for precise alignment, the effective range is cropped by image preprocessing algorithm, the phase is analyzed by Fourier transform, and the phase difference of the moiré interference fringe is calculated, so as to adjust the relative position relationship between the mask alignment mark grating and the substrate alignment mark grating; When the mask alignment mark grating and substrate alignment mark grating are offset When , the complex amplitude of the moiré fringe is expressed as: ， ， in , The grating frequency of the mask alignment mark grating and the substrate alignment mark grating; The complex amplitude distribution of the moiré fringes formed by the superposition of the grating of the mask alignment mark and the corresponding grating on the substrate alignment mark; A complex amplitude distribution of moiré fringes formed by superposition of another grating of the mask alignment mark and a corresponding grating of the substrate alignment mark; The cycle is and The gratings together form a period of The moiré fringes of the two gratings are calculated by the phase difference between them: ， ， ， Solve for the offset between the mask and substrate alignment mark grating: 。

Images