CN115561979A - Moire alignment device and method for projection lithography - Google Patents

Moire alignment device and method for projection lithography Download PDF

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CN115561979A
CN115561979A CN202211207341.7A CN202211207341A CN115561979A CN 115561979 A CN115561979 A CN 115561979A CN 202211207341 A CN202211207341 A CN 202211207341A CN 115561979 A CN115561979 A CN 115561979A
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moire
alignment
moire fringes
mark
mask
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李天�
周绍林
陈志坚
李斌
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South China University of Technology SCUT
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7003—Alignment type or strategy, e.g. leveling, global alignment
    • G03F9/7046—Strategy, e.g. mark, sensor or wavelength selection
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7073—Alignment marks and their environment

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Abstract

The invention discloses a projection photoetching Moire alignment device and the device includes: the device comprises an illumination system, a mask mark, a photoetching projection objective, an alignment mark, a DMD space modulator, a CCD camera and a sensor motion platform; the illumination system emits light rays, and the light rays form a space image through the photoetching projection objective after passing through the mask mark; searching the position of the space image by controlling the movement of the sensor motion table, so that the light passing through the alignment mark is diffracted to form moire fringes; the Moire fringes reach a DMD space modulator to be encoded; the coded moire fringes reach a CCD (charge coupled device) camera, and the moire fringes are reconstructed according to the acquired light intensity information; and acquiring the position deviation between the ideal imaging and the actual imaging according to the reconstructed moire fringes, and feeding the position deviation back to the sensor motion platform for correction to realize alignment. The invention does not need a spatial filter, has simpler optical system, reduces the hardware cost and can be widely applied to the technical field of optical precision detection.

Description

Moire alignment device and method for projection lithography
Technical Field
The invention relates to the technical field of optical measurement and optical precision detection of a photoetching machine system, in particular to a projection photoetching Moire alignment device and a method.
Background
In the field of semiconductor manufacturing, a lithography machine is one of the core technologies that promote the industry development, and as a lithography projection objective lens of one of three core systems of the lithography machine, the imaging quality determines whether the definition of an exposure line and an overlay error meet a tolerance, so that an actual imaging position must be detected and corrected to achieve a position close to an ideal imaging position. Common lithographic alignment methods include bright and dark field alignment, grating diffraction alignment, aerial image sensors, and moire fringe alignment.
The bright field and dark field alignment is a photometric alignment method, bright field images come from reflected light and scattered light of an alignment mark on a silicon wafer, dark field images come from scattered light and diffracted light at the edge of the alignment mark and block direct reflected light, and the bright field alignment has stronger signal intensity than the dark field alignment but has lower precision than the dark field alignment.
In the grating diffraction, alignment light is generally used to diffract an alignment mark, a spatial filter is added in the middle to filter out unwanted orders, the alignment mark interferes with a mark on a mask mark through an imaging system, and a sensor recording signal is demodulated to obtain a position offset.
The mask mark and the alignment mark with the same design shape as the sensor in the space are scanned in an imaging view field through the workpiece table, so that the space image formed by the alignment mark on the workpiece table and the mask mark is convoluted, a light intensity signal is converted into an electric signal, the maximum value of the signal is an alignment position, and imaging offset is obtained through analog-to-digital conversion. The aerial image sensor has high alignment precision and can scan three-dimensional aerial image information, but a corresponding TIS mark needs to be designed, the detection time is long, and the precision is limited by a workpiece table.
The traditional moire fringe alignment method adopts the mode that a beam of laser is irradiated on an alignment mark on a silicon chip, then reflected light is irradiated on a reference mark on a mask mark after passing through a spatial filter and a projection objective, moire fringes are generated due to a diffraction effect, and finally a photoelectric detector is used for receiving optical signals to detect the position offset of actual imaging and ideal imaging. This approach is simple in principle and does not require expensive equipment, but the alignment requires an additional laser path and also requires a spatial filter to intercept the '± 1' order diffracted light.
Disclosure of Invention
To solve at least some of the problems of the prior art, it is an object of the present invention to provide a moire alignment device and method for projection lithography.
The technical scheme adopted by the invention is as follows:
a projection lithography moire alignment device, comprising: an illumination system, a mask mark, a photoetching projection objective, an alignment mark, a DMD space modulator, a CCD camera and a sensor motion platform; the alignment mark, the DMD spatial modulator and the CCD camera are arranged on a sensor motion platform;
the illumination system emits light rays, and the light rays form a space image through the photoetching projection objective after passing through the mask mark; searching the position of the space image by controlling the movement of the sensor motion platform, so that the space image and the alignment mark are diffracted to form moire fringes; moire fringe reaches DMD space modulator to encode; the coded moire fringes reach a CCD camera, and the moire fringes are reconstructed according to the acquired light intensity information; and acquiring the position deviation between the ideal imaging and the actual imaging according to the reconstructed moire fringes, and feeding the position deviation back to the sensor motion platform for correction to realize alignment. Wherein the ideal imaging can be calculated in advance through simulation.
Further, the intensity distribution of the mask mark is:
Figure BDA0003874546370000021
the intensity distribution of the alignment mark is as follows:
Figure BDA0003874546370000022
wherein f is 1 Frequency, f, representing mask marks 2 Representing the frequency of the alignment mark; t is t xy1 For the x, y coordinates of the mask marks, t xy2 The x, y coordinates of the alignment marks.
Further, the space image is a superposition of a group of mutually incoherent point light sources in the image surface intensity distribution.
Further, the aerial image I is represented as follows:
Figure BDA0003874546370000023
in the formula, I is an aerial image,
Figure BDA0003874546370000024
is diffraction light amplitude, P is a pupil function, S is an effective light source, and FT is two-dimensional Fourier transform;
the conversion to discrete form is as follows:
Figure BDA0003874546370000025
Figure BDA0003874546370000026
Figure BDA0003874546370000027
Figure BDA0003874546370000028
wherein, the wave number k =2 pi/lambda, and lambda is the wavelength of the monochromatic light source; w aberration (f, g) is wave aberration, where n is of Zernike order, zn is a Zernike polynomial coefficient of nth order, R n (ρ, θ) is the nth order Zernike polynomial of pupil plane regularization; f. g is the pupil spectral coordinate, f ', g' are the source spectral coordinates.
Further, the expression of the moire fringes is:
Figure BDA0003874546370000031
in the formula I y1 (x, y) represents the light intensity distribution of the mask mark, I y2 (x, y) represents the light intensity distribution of the alignment mark.
Further, the reconstructing the moire fringes according to the acquired light intensity information includes:
and reconstructing the moire fringes by adopting a compressed sensing algorithm at a lower sampling rate, wherein the sparsity of moire fringe signals is improved by using wavelet transformation in the reconstruction process.
Further, the expression of the moire fringes obtained by reconstruction is:
I more ＝Φx＝ΦΨs＝As
in the formula, phi represents an M multiplied by N dimension random measurement matrix, psi represents an N multiplied by N dimension wavelet transformation orthogonal base, s is an N multiplied by 1 dimension sparse signal of an original signal after wavelet transformation, and A represents an M multiplied by N dimension observation matrix consisting of the measurement matrix and the wavelet orthogonal base; m represents the number of random matrix code measurements, and N represents the measurement signal length.
Further, the acquiring the position deviation of the ideal imaging and the actual imaging according to the reconstructed moire fringes comprises:
the position deviation between ideal imaging and actual imaging is obtained by detecting the mass center coordinate offset of the moire fringes;
the expression of the positional deviation is:
Figure BDA0003874546370000032
Figure BDA0003874546370000033
wherein X and Y are barycentric coordinates under ideal imaging,
Figure BDA0003874546370000034
is the moire fringe centroid coordinates in the misaligned state.
Further, the projection lithography moire alignment device further comprises a mask stage, a first convex lens and a second convex lens;
the mask table is used for placing mask marks;
the first convex lens is arranged between the alignment mark and the DMD spatial modulator, and light rays passing through the alignment mark enter the DMD spatial modulator through the first convex lens;
the second convex lens is arranged between the DMD spatial modulator and the CCD camera, and the coded light rays pass through the second convex lens to reach the CCD camera.
The invention adopts another technical scheme that:
a projection lithography moire alignment method is applied to the projection lithography moire alignment device, and comprises the following steps:
the illumination system emits light rays, and the light rays form a space image through the photoetching projection objective after passing through the mask mark;
searching the position of the space image by controlling the movement of the sensor motion platform, so that the light passing through the alignment mark is diffracted to form moire fringes;
the Moire fringes reach a DMD space modulator to be encoded;
the coded moire fringes reach a CCD (charge coupled device) camera, and the moire fringes are reconstructed according to the acquired light intensity information;
and acquiring the position deviation between the ideal imaging and the actual imaging according to the reconstructed moire fringes, and feeding the position deviation back to the sensor motion platform for correction to realize alignment.
The beneficial effects of the invention are: the invention does not need a spatial filter, the optical system is simpler, and the hardware cost is reduced; in addition, the storage space required by CCD array sampling is reduced by a coding-in-reconstruction mode.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description is made on the drawings of the embodiments of the present invention or the related technical solutions in the prior art, it should be understood that the drawings in the following description are only for convenience and clarity of describing some embodiments in the technical solutions of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a projection lithography Moire alignment apparatus according to an embodiment of the present invention;
FIG. 2 is a schematic illustration of a mask mark and an alignment mark in an embodiment of the present invention;
FIG. 3 is a schematic diagram of an ideal imaging in an embodiment of the invention;
FIG. 4 is a schematic view of alignment position deviation detection in an embodiment of the present invention;
FIG. 5 is a flowchart illustrating steps of a method for projection lithography Moire alignment according to an embodiment of the present invention.
Reference numbers of fig. 1: 1. an illumination system; 2. marking a mask; 3. a mask stage; 4. photoetching projection objective lens; 5. aligning the mark; 6. a first convex lens; 7. a DMD spatial modulator; 8. a second convex lens; 9. a CCD camera; 10. a sensor motion stage.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention and are not to be construed as limiting the present invention. For the step numbers in the following embodiments, they are set for convenience of illustration only, the order between the steps is not limited at all, and the execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.
In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings only for the convenience of description of the present invention and simplification of the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.
Interpretation of terms:
mask marking: refers to a mask raster pattern; in the present invention, light is transmitted through it, transmitting the pattern on the image plane and diffracting it with the alignment marks to form moire fringes.
Based on the problems existing in the prior art, the invention provides a moire fringe photoetching alignment method based on compressed sensing, under the irradiation of an illumination light source, a mask mark grating pattern is diffracted with alignment marks with different workpiece table frequencies after passing through a projection objective lens to form moire fringes, the moire fringes are collected by a CCD after passing through a lens and a DMD coded measurement matrix, and finally the position offset of actual imaging and ideal imaging is detected through an algorithm. Compared with the traditional method, the method does not need a spatial filter, has simpler optical system, reduces the cost, and reduces the storage space required by CCD array sampling.
As shown in fig. 1, a projection lithography moire alignment device comprises an illumination system 1, a mask mark 2, a mask stage 3, a lithography projection objective 4, an alignment mark 5, a first convex lens 6, a DMD spatial modulator 7, a second convex lens 8, a CCD camera 9 and a sensor motion stage 10. The alignment mark 5, the first convex lens 6, the DMD spatial modulator 7, the second convex lens 8, and the CCD camera 9 are provided on a sensor moving stage 10, and move following the movement of the sensor moving stage 10.
The working principle of the device is as follows: the method comprises the steps that a mask mark is irradiated by an emission light source of an illumination system to form a space image through a projection objective, a sensor motion platform bears an alignment mark to scan and find the position of the space image of the mask mark, moire fringes are formed through diffraction, the moire fringes are collected by a CCD after being incident to the surface of a DM space modulator through a lens and are accurately reconstructed through a compressed sensing algorithm at a low sampling rate, the position deviation between ideal imaging and actual imaging is obtained through detecting the coordinate offset of the centroid of the moire fringes, and the position deviation is fed back to the sensor motion platform to be corrected, so that alignment can be achieved.
As an alternative embodiment, the movement of the sensor motion stage may be controlled manually to find the aerial image position. As another optional implementation, the movement of the sensor motion stage can be controlled in an automatic manner, a movement track path and a step length are preset, each movement step is acquired through a CCD, and whether moire fringes appear or not is judged; when the occurrence of moire fringes is detected, the moving step is stopped. It should be noted that, besides the above two manners, other manners of control may also be used, and other manners of control should fall within the scope of the present invention.
Further as an optional implementation manner, the projection lithography moire alignment device further comprises an upper computer, and the upper computer, the DMD spatial modulator, the CCD camera and the sensor motion table are used for controlling the working states of the DMD spatial modulator, the CCD camera and the sensor motion table.
FIG. 2 is a schematic diagram of a mask mark and an alignment mark, distributed as:
Figure BDA0003874546370000061
wherein: y is 1 Is the intensity distribution of the mask mark, y 2 Is the intensity distribution of the alignment mark, f 1 ，f 2 Representing the frequency of the mask marks and alignment marks, i.e. the inverse of the period T. In this embodiment, the mask mark period is 8um, and the alignment mark period is 2um. Wherein FIG. 2 (a) is a schematic diagram of a mask markFig. 2 (b) is a schematic diagram of an alignment mark.
FIG. 3 is an idealized imaging schematic, the imaging process in optical lithography being modeled as a pupil function with a partially coherent light source, i.e., a partially coherent system. The system is regarded as a group of mutually incoherent point light sources, and the intensity distribution on the whole image surface is the superposition of the intensities formed by all the point light sources. In abbe's theory, the aerial image is computed directly from the sum of all point sources, each of which requires a Fourier Transform (FT). The analytical representation of the abbe method can be written as:
Figure BDA0003874546370000062
in the formula, I is an aerial image,
Figure BDA0003874546370000063
for diffracted light amplitude, P is the pupil function, S is the effective source, and FT is the two-dimensional Fourier transform. We can rewrite the aerial image intensity I to discrete form:
Figure BDA0003874546370000064
the pupil function represents the properties of the entire projection objective, which include the wave aberration in the projection objective:
Figure BDA0003874546370000065
wherein the wave number k =2 pi/lambda, lambda is the wavelength of the monochromatic light source, is Waberrati on (f, g) wave aberration, which can be characterized by orthogonal zernike polynomial expansion:
Figure BDA0003874546370000071
wherein n is a Zernike order, zn is a coefficient of an nth Zernike polynomial, R n (ρ, θ) is the nth order Zernike polynomial of the pupil plane regularization, ideally with a wave aberration of 0.
Fig. 4 shows a schematic diagram of moire detection in the case of a deviation of the imaging position from the ideal position, in which case the pupil function is not 0, the x and y offset errors are included, and the moire fringes can be characterized by the Z2 and Z3 terms in the zernike polynomial, and the generated moire fringes can be characterized as:
Figure BDA0003874546370000072
the compressive sensing algorithm carries out immediate coding through a DMD spatial modulator to construct a measurement matrix, wavelet transformation is used as an orthogonal basis to improve the sparsity of original signals, and moire fringes can be accurately reconstructed at a sampling rate as low as 0.2:
I more ＝Φx＝ΦΨs＝As (7)
phi represents an M multiplied by N dimension random measurement matrix, psi represents an N multiplied by N dimension wavelet transformation orthogonal base, s is an N multiplied by 1 dimension sparse signal of an original signal after wavelet transformation, and A represents an M multiplied by N dimension observation matrix consisting of the measurement matrix and the wavelet orthogonal base. M represents the random matrix code measurement times, and N represents the measurement signal length.
Finally by reconstructing the centroid offset of the moire fringes, we can get the alignment offset:
Figure BDA0003874546370000073
wherein X and Y are barycentric coordinates under ideal imaging,
Figure BDA0003874546370000074
are the moire fringe centroid coordinates in the misaligned state. The offset is fed back to the sensor motion platform for correction, and photoetching alignment can be realized.
Referring to fig. 5, based on the above apparatus, the present embodiment further provides a projection lithography moire alignment method, including the following steps:
s1, the illumination system emits light rays, and after the light rays pass through the mask mark, a space image is formed through the photoetching projection objective.
The illuminating system emits a light source to irradiate the mask mark to form an aerial image through the magnification scaling of the projection objective and the Abbe imaging principle.
And S2, searching the position of the space image by controlling the movement of the sensor motion table, so that the light passing through the alignment mark is diffracted, and moire fringes are formed.
The sensor motion stage scans the alignment marks to locate the aerial image of the mask marks and diffracts the aerial image of the mask marks to form moire fringes.
And S3, the Moire fringes reach a DMD space modulator for encoding.
The moire fringes are incident on the surface of the DMD spatial modulator through the lens, the DMD can generate '0' and '1' arrays in a random mode, wherein '0' represents no reflection, '1' represents reflection, and the encoded moire fringes are collected by the CCD.
And S4, the coded moire fringes reach the CCD camera, and the moire fringes are reconstructed according to the acquired light intensity information.
The light intensity information acquired by the CCD camera is subjected to wavelet transformation, the sparsity of signals is improved, so that the precision of compressed sensing reconstruction is improved, the compressed sensing algorithm is used for accurately reconstructing moire fringes at a lower sampling rate and performing interpolation fitting, and the calculation storage space is greatly saved.
And S5, acquiring the position deviation between the ideal imaging and the actual imaging according to the reconstructed Moire fringes, and feeding the position deviation back to the sensor motion platform for correction to realize alignment.
The position deviation between ideal imaging and actual imaging is obtained by detecting the offset of moire fringe centroid coordinates reconstructed by interpolation fitting, and the position deviation amount is fed back to the sensor motion platform for correction, so that alignment can be realized.
Compared with the traditional method, the method has the advantages that a space filter is not needed, the optical system is simpler, the cost is reduced, and the storage space required by CCD array sampling is reduced.
In the foregoing description of the specification, reference to the description of "one embodiment/example," "another embodiment/example," or "certain embodiments/examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

1. A projection lithography moire alignment device, comprising: the device comprises an illumination system, a mask mark, a photoetching projection objective, an alignment mark, a DMD space modulator, a CCD camera and a sensor motion platform; the alignment mark, the DMD spatial modulator and the CCD camera are arranged on a sensor motion table;
the illumination system emits light rays, and the light rays form a space image through the photoetching projection objective after passing through the mask mark; searching the position of the space image by controlling the movement of the sensor motion platform so as to diffract the space image and the alignment mark to form moire fringes; the Moire fringes reach a DMD space modulator to be encoded; the coded moire fringes reach a CCD camera, and the moire fringes are reconstructed according to the acquired information; and acquiring the position deviation between ideal imaging and actual imaging according to the reconstructed moire fringes, and feeding the position deviation back to the sensor motion platform for correction to realize alignment.
2. A projection lithography moire alignment device as claimed in claim 1, characterized in that said mask marks have an intensity distribution of:
Figure FDA0003874546360000011
the intensity distribution of the alignment mark is as follows:
Figure FDA0003874546360000012
wherein f is 1 Representing the frequency of the mask marks, f 2 Representing the frequency of the alignment mark; t is t xy1 For the x, y coordinates of the mask marks, t xy2 Is the x, y coordinate of the alignment mark.
3. A projection lithography moire alignment device as claimed in claim 1 wherein said aerial image is a superposition of a set of mutually incoherent point light sources at the image plane intensity distribution.
4. A projection lithography moire alignment device as claimed in claim 3, characterized in that said aerial image I is represented as follows:
Figure FDA0003874546360000013
in the formula, I is a space image,
Figure FDA0003874546360000014
is diffraction light amplitude, P is a pupil function, S is an effective light source, and FT is two-dimensional Fourier transform;
the conversion to discrete form is as follows:
Figure FDA0003874546360000015
Figure FDA0003874546360000016
Figure FDA0003874546360000017
Figure FDA0003874546360000021
wherein, the wave number k =2 pi/lambda, and lambda is the wavelength of the monochromatic light source; w aberration (f, g) is wave aberration, where n is of Zernike order, zn is a Zernike polynomial coefficient of nth order, R n (ρ, θ) is the nth order Zernike polynomial of pupil plane regularization; f. g is the pupil spectral coordinate, f ', g' are the source spectral coordinates.
5. A projection lithographic moire alignment device as claimed in claim 4, characterized in that said moire patterns are expressed by:
Figure FDA0003874546360000022
in the formula I y1 (x, y) represents the light intensity distribution of the mask mark, I y2 (x, y) represents the light intensity distribution of the alignment mark.
6. The projection lithography moire alignment device as claimed in claim 1, wherein said reconstructing moire fringes from collected light intensity information comprises:
reconstructing moire fringes by adopting a compressed sensing algorithm at a lower sampling rate; wherein wavelet transformation is used in the reconstruction process to improve sparsity of moire fringe signals.
7. A projection lithographic moire alignment device as in claim 6, wherein said moire fringes obtained by said reconstruction are expressed by:
I more ＝Φx＝ΦΨs＝As
in the formula, phi represents an M multiplied by N dimension random measurement matrix, psi represents an N multiplied by N dimension wavelet transformation orthogonal base, s is an N multiplied by 1 dimension sparse signal of an original signal after wavelet transformation, and A represents an M multiplied by N dimension observation matrix consisting of the measurement matrix and the wavelet orthogonal base; m represents the number of random matrix code measurements, and N represents the measurement signal length.
8. The projection lithography moire alignment device as claimed in claim 1, wherein said obtaining of the positional deviation of the ideal imaging from the actual imaging from the reconstructed moire fringes comprises:
the position deviation between ideal imaging and actual imaging is obtained by detecting the mass center coordinate offset of the moire fringes;
the expression of the positional deviation is:
Figure FDA0003874546360000023
Figure FDA0003874546360000024
wherein X and Y are barycentric coordinates under ideal imaging,
Figure FDA0003874546360000025
are the moire fringe centroid coordinates in the misaligned state.
9. A projection lithography moire alignment device as claimed in claim 1, further comprising a mask stage, a first convex lens and a second convex lens;
the mask table is used for placing mask marks;
the first convex lens is arranged between the alignment mark and the DMD spatial modulator, and light rays passing through the alignment mark enter the DMD spatial modulator through the first convex lens;
the second convex lens is arranged between the DMD spatial modulator and the CCD camera, and the coded light rays reach the CCD camera through the second convex lens.
10. A projection lithography moire alignment method applied to a projection lithography moire alignment device as claimed in any one of claims 1 to 9, comprising the steps of:
the illumination system emits light rays, and the light rays form a space image through the photoetching projection objective after passing through the mask mark;
searching the position of the space image by controlling the movement of the sensor motion platform, so that the light passing through the alignment mark is diffracted to form moire fringes;
moire fringe reaches DMD space modulator to encode;
the coded moire fringes reach a CCD camera, and the moire fringes are reconstructed according to the acquired information;
and acquiring the position deviation between ideal imaging and actual imaging according to the reconstructed moire fringes, and feeding the position deviation back to the sensor motion platform for correction to realize alignment.
CN202211207341.7A 2022-09-30 2022-09-30 Moire alignment device and method for projection lithography Pending CN115561979A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116128931A (en) * 2023-04-14 2023-05-16 山东大学 Full-spectrum rapid positioning system and method based on mask space regulation and control

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116128931A (en) * 2023-04-14 2023-05-16 山东大学 Full-spectrum rapid positioning system and method based on mask space regulation and control

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