CN117572735A - Static alignment system and method based on phase grating - Google Patents
Static alignment system and method based on phase grating Download PDFInfo
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- 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
- G03F9/7076—Mark details, e.g. phase grating mark, temporary mark
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- 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
- G03F9/7023—Aligning or positioning in direction perpendicular to substrate surface
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- 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
- G03F9/7084—Position of mark on substrate, i.e. position in (x, y, z) of mark, e.g. buried or resist covered mark, mark on rearside, at the substrate edge, in the circuit area, latent image mark, marks in plural levels
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Abstract
The application provides a static alignment system and an alignment method based on a phase grating, wherein incident light emitted from a light source irradiates a diffraction beam screening lens group through a rotating flat plate, the incident light irradiates an alignment mark on the surface of a sample to be detected through the diffraction beam screening lens group and a first lens in sequence to generate diffraction beams of each order, the diffraction beams of each order are filtered and screened through the diffraction beam screening lens group to obtain multiple groups of target order diffraction beams, the multiple groups of target order diffraction beams generate different orders of interference fringes on the surface of a reference grating, and an alignment signal acquisition unit acquires periodic sinusoidal light intensity signals formed by each order of interference fringe and transmits the periodic sinusoidal light intensity signals to an upper computer so as to realize calculation of alignment positions of the sample to be detected through the upper computer. According to the method and the device, the angle dynamic modulation is carried out on the illumination beam through the rotating flat plate, so that the position diffraction information of the alignment mark can be synchronously obtained without the displacement of the alignment mark, static scanning is realized, and the alignment precision is improved.
Description
Technical Field
The present disclosure relates to the field of photolithography, and in particular, to a static alignment system and an alignment method based on a phase grating.
Background
Along with the development of integrated circuit manufacturing equipment to high precision and high yield, higher requirements are put forward on the manufacturing integration precision and process adaptability of the equipment, and particularly, an alignment system is a core function for realizing accurate operation position of precision equipment and small repeated processing and manufacturing errors.
The traditional alignment technology mainly comprises two alignment modes of imaging alignment and phase grating scanning alignment, wherein the imaging alignment is realized based on image recognition and photoelectric sensor detection, such as patent CN103309169B of Canon corporation and Shanghai microelectronic patent CN106483777B, the processing, adjustment and manufacture difficulties are high, the aberration control is strict, the alignment requirements under complex working conditions are difficult to meet, the phase grating scanning alignment mode is mainly used for alignment by collecting high-order diffraction signals, such as ASML patent CN1506768B, nikon CN111045302A and the like, but the alignment mode is complex to assemble and can only be used for acquiring the current position information by scanning.
Disclosure of Invention
In view of this, the present application aims at providing at least a static alignment system and an alignment method based on a phase grating, where the application dynamically modulates an angle of an illumination beam by rotating a flat plate, so that position diffraction information of an alignment mark can be obtained synchronously without displacement of the alignment mark, static scanning is achieved, and alignment accuracy is improved.
The application mainly comprises the following aspects:
in a first aspect, an embodiment of the present application provides a static alignment system based on a phase grating, the static alignment system includes an alignment subsystem, a first lens and an upper computer, where the alignment subsystem includes a light source, a rotating flat plate, a second lens, a reference grating, an alignment signal acquisition unit and a diffraction beam screening lens set disposed between the first lens and the second lens, the rotating flat plate is mounted on a rotating motor, the rotating motor is driven and controlled by the upper computer so that the upper computer drives the rotating flat plate to rotate, where an incident light emitted from the light source generates a light offset through the rotating flat plate and irradiates the light offset to the diffraction beam screening lens set, the incident light sequentially irradiates an alignment mark on a sample surface to be measured through the diffraction beam screening lens set and the first lens, the alignment mark is a phase grating structure in a horizontal XY direction, each order of diffracted beams carrying position information are diffracted in the XY direction under the action of the incident light, each order of diffracted beams passes through the first lens and irradiates the diffraction beam screening lens set in a parallel light posture, each order of diffracted beams is filtered and screened by the diffraction screening lens set in order to obtain multiple groups of diffraction beams, and the target orders are transferred to the second diffraction lens; after the multiple groups of target order diffraction beams pass through the second lens, different orders of interference fringes are generated on the surface of the reference grating, grating marks with the same period as that of each formed order of interference fringes are processed on the surface of the reference grating, and each order of interference fringe irradiates on the reference grating with the same period as that of the corresponding order of interference fringe; the alignment signal acquisition unit is tightly attached to each reference grating to acquire periodic sinusoidal light intensity signals formed by each level interference fringe at the position corresponding to the reference grating, and transmits the periodic sinusoidal light intensity signals corresponding to each level interference fringe to the upper computer, and the upper computer utilizes the periodic sinusoidal light intensity signals generated by each reference grating to realize the calculation of the static alignment position of the sample to be detected.
In one possible implementation manner, the static alignment system further comprises an incident optical fiber, a collimating lens and a focusing lens, wherein the incident optical fiber, the collimating lens and the focusing lens are sequentially arranged between the light source and the rotating flat plate, the collimating lens and the focusing lens are lens groups with positive optical power, the incident optical fiber is a single-mode polarization-preserving optical fiber, and after light emitted from the light source passes through the incident optical fiber, a beam of emergent light with preset wavelength and preset polarization state is emitted; the emergent light is converted into parallel light through the collimating lens and is transmitted to the focusing lens; parallel light rays sequentially pass through the focusing lens and the rotating flat plate and are converged on focal planes of the first lens and the second lens.
In one possible implementation manner, the diffraction beam screening lens group comprises a reflecting prism and an order diaphragm, the reflecting prism is arranged at the pupil surface of the focusing lens, a plurality of light passing holes for carrying out preset order diffraction beam screening are preset on the order diaphragm, wherein incident light rays emitted from a light source are converged on the reflecting prism through a rotating flat plate, and light spots which do circular motion along with the rotation modulation of the light beams are formed on the surface of the reflecting prism; the light spots performing circular motion form illumination light beams to be incident to the first lens under the reflection effect of the reflecting prism; after passing through the first lens, the incident light irradiates on an alignment mark on the surface of the sample to be measured in a parallel light posture.
In one possible implementation manner, when each order diffraction beam passing through the first lens passes through the order diaphragm, the plurality of light passing holes on the order diaphragm filter and screen each order diffraction beam to obtain a plurality of groups of target order diffraction beams, and the plurality of groups of target order diffraction beams irradiate to the second lens.
In one possible implementation manner, the diffraction beam screening lens group further comprises an order separation component arranged between the second lens and the reflecting prism, wherein the order separation component is formed by combining and bonding multiple wedge angles, and multiple groups of target order diffraction beams are deflected and separated to different directions by the order separation component to obtain multiple groups of target order diffraction beams which propagate to different directions in space; each group of target order diffraction light beams after deflection separation is incident to the second lens with propagation angle information corresponding to the target order diffraction light beams, and the propagation angle information indicates the deflection angle of the target order diffraction light beams propagated to the space by the order separation component.
In one possible implementation manner, the deflection angles of the positive-order diffraction light beam and the negative-order diffraction light beam with the same order are the same, the order separation component is arranged at the focal plane positions of the first lens and the second lens, multiple groups of target order diffraction light beams passing through the second lens perform coherent superposition interference on the reference grating for the positive-order diffraction light beam and the negative-order diffraction light beam with the same order, and different order interference fringes are generated on the surface of the reference grating.
In one possible implementation manner, the static alignment system of the phase grating further comprises another alignment subsystem with the same structure as the alignment subsystem, the alignment system further comprises a polarization beam splitter group arranged between the secondary diaphragm and the first lens, the two alignment subsystems are positioned at two sides of the polarization beam splitting surface corresponding to the polarization beam splitter group, the incident light beams emitted by the two alignment subsystems are different in corresponding wavelength, and each alignment subsystem is provided with: incident light beams passing through the secondary diaphragm are incident to the polarization spectroscope group; the polarization spectroscope group combines the incident light beams which come from the two alignment subsystems, have two different wavelengths and have linear polarization states at the alignment mark according to the polarization states corresponding to the two alignment subsystems; the polarized light after beam combination is reflected to the first lens, and is incident to the polarized spectroscope group through the first lens, the polarized spectroscope group is used for beam splitting, and the obtained two incident light beams are respectively incident to the corresponding alignment systems so as to realize the static alignment of the dual-wavelength phase grating through the subsequent light path.
In one possible embodiment, the rotation axis of the rotation plate is at a preset angle to the surface of the rotation plate.
In one possible implementation, the alignment signal acquisition unit includes a signal fiber and a signal acquisition board that is affixed to each reference grating, wherein for each reference grating: the method comprises the steps that a signal optical fiber clung to a reference grating is used for collecting periodic sinusoidal light intensity signals formed at the position of the reference grating, and the collected periodic sinusoidal light intensity signals are sent to a signal collecting board card by the signal optical fiber; the signal acquisition board card carries out signal conversion, demodulation and amplification processing on the received periodic sinusoidal light intensity signals acquired through the reference grating, and transmits the processed periodic sinusoidal light intensity signals to the upper computer; and the upper computer finishes the static position alignment of the sample to be detected based on the processed periodic sinusoidal light intensity signals corresponding to each reference grating by using a preset algorithm.
In a second aspect, embodiments of the present application further provide an alignment method applied to the static alignment system based on phase grating of any one of claims 1 to 9, the method comprising: the upper computer drives the rotating flat plate to rotate through the rotating motor; the method comprises the steps that incident light rays emitted by a light source irradiate on an alignment mark on the surface of a sample to be detected through a rotating flat plate, a diffraction beam screening lens group and a first lens at a variable incident angle, the alignment mark is a phase grating structure mark in the horizontal XY direction, each order of diffraction beam carrying position information is diffracted by the alignment mark in the XY direction under the action of the incident light rays with the continuously variable incident angle, each order of diffraction beam passes through the first lens and irradiates on the diffraction beam screening lens group in a parallel light posture, each order of diffraction beam is filtered and screened through the diffraction beam screening lens group, and a plurality of groups of target orders of diffraction beams are obtained and transmitted to a second lens; after the multiple groups of target order diffraction beams pass through the second lens, different orders of interference fringes are generated on the surface of the reference grating under the action of the second lens, grating marks with the same period as that of each formed order of interference fringes are processed on the surface of the reference grating, and each order of interference fringe irradiates on the reference grating with the same period as that of the corresponding order of interference fringe; the alignment signal acquisition unit is tightly attached to each reference grating to acquire periodic sinusoidal light intensity signals formed by each level interference fringe at the corresponding reference grating under the action of the movement of the rotating flat plate, and transmits the periodic sinusoidal light intensity signals corresponding to each level interference fringe to the upper computer, and the upper computer utilizes the periodic sinusoidal light intensity signals generated at each reference grating to realize the calculation of the static alignment position of the sample to be detected.
The application provides a static alignment system and alignment method based on phase grating, wherein, the incident light that sends from the light source passes through rotatory flat board, shine to the diffraction beam screening lens group, the incident light passes through diffraction beam screening lens group and first lens in proper order and shines on the alignment mark of sample surface to be measured, produce each order diffraction beam, carry out filtering screening to each order diffraction beam through diffraction beam screening lens group, obtain multiunit target order diffraction beam, multiunit target order diffraction beam produces different grades interference fringe at the reference grating surface, alignment signal acquisition unit gathers periodic sinusoidal light intensity signal that each order interference fringe formed through reference grating and transmits to the host computer, in order to realize the calculation of sample alignment position to be measured through the host computer. According to the method and the device, the angle dynamic modulation is carried out on the illumination beam through the rotating flat plate, so that the position diffraction information of the alignment mark can be synchronously obtained without the displacement of the alignment mark, the static scanning alignment is realized, and the alignment precision is improved.
The application has the advantages that:
1. the alignment system adopts a phase grating alignment system, and is different from the traditional dynamic scanning phase grating alignment system, and the rotation flat plate is added to perform an angle dynamic modulation on the illumination beam, so that the alignment system can synchronously obtain the position diffraction information of the alignment mark without the displacement of the alignment mark, and realize the function of static scanning.
2. The grating alignment mark introduced by the invention can flexibly adapt to the main stream phase grating alignment mark existing in the current market, such as: PM, XPA, SPM, etc.
In order to make the above objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered limiting the scope, and that other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 illustrates one of the structural schematic diagrams of a static alignment system provided in an embodiment of the present application;
FIG. 2 is a schematic diagram of a second embodiment of a static alignment system;
FIG. 3 is a third schematic diagram of a static alignment system according to an embodiment of the present disclosure;
FIG. 4 shows a fourth schematic structural diagram of a static alignment system according to an embodiment of the present application;
FIG. 5a is a schematic view illustrating the incidence of two light beams with different polarization states according to an embodiment of the present application;
FIG. 5b is a schematic view illustrating two light beams with different polarization states according to an embodiment of the present disclosure;
FIG. 6a shows one of the incidence diagrams of two light beams of the same polarization state provided in the embodiments of the present application;
FIG. 6b shows a second schematic view of the incidence of two light beams of the same polarization state according to the embodiment of the present application;
fig. 6c shows an outgoing schematic diagram of two light beams with the same polarization state according to an embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it should be understood that the accompanying drawings in the present application are only for the purpose of illustration and description, and are not intended to limit the protection scope of the present application. In addition, it should be understood that the schematic drawings are not drawn to scale. A flowchart, as used in this application, illustrates operations implemented according to some embodiments of the present application. It should be appreciated that the operations of the flow diagrams may be implemented out of order and that steps without logical context may be performed in reverse order or concurrently. Moreover, one or more other operations may be added to the flow diagrams and one or more operations may be removed from the flow diagrams as directed by those skilled in the art.
In addition, the described embodiments are only some, but not all, of the embodiments of the present application. The components of the embodiments of the present application, which are generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, as provided in the accompanying drawings, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, are intended to be within the scope of the present application.
The traditional alignment technology mainly comprises two alignment modes of imaging alignment and phase grating scanning alignment, wherein the imaging alignment is realized based on image recognition and photoelectric sensor detection, such as patent CN103309169B of Canon company and Shanghai microelectronic patent CN106483777B, the processing, assembling and manufacturing difficulties are high, aberration control is strict, and the alignment requirements under complex working conditions are difficult to meet. The phase grating scanning alignment is mainly performed by collecting higher-order diffraction signals, such as those of ASML patent CN1506768B and nikon CN111045302 a. This alignment is complex to assemble and the current position information can only be obtained by scanning.
Based on this, the embodiment of the application provides a static alignment system and an alignment method based on a phase grating, which specifically comprises the following steps:
referring to fig. 1, fig. 1 shows one of structural diagrams of a static alignment system according to an embodiment of the present application. As shown in fig. 1, the static alignment system provided in the embodiment of the application includes at least one alignment subsystem, a first lens 31 and a host computer 6, the alignment subsystem includes a light source 1, a rotating flat plate 2, a second lens 32, a reference grating 4, an alignment signal acquisition unit 5, the host computer 6 and a diffraction beam screening lens group 7 disposed between the first lens 31 and the second lens 32, wherein the second lens 32 in each alignment subsystem and the first lens 31 form a 4F optical structure.
Wherein the rotating plate 2 is mounted on a rotating motor (not shown in the figure), and the rotating motor is driven and controlled by the upper computer 6, so that the upper computer 6 drives the rotating plate 2 to rotate through the rotating motor.
After the incident light emitted from the light source 1 is deflected by the rotating flat plate 2, the incident light irradiates the diffraction beam screening lens group 7, and the incident light sequentially irradiates an alignment mark on the surface of the sample 8 to be measured through the diffraction beam screening lens group 7 and the first lens 31, wherein the alignment mark is a phase grating structure mark in the horizontal XY direction.
The alignment mark diffracts each order diffraction beam carrying position information in the XY direction under the action of incident light, each order diffraction beam passes through the first lens 31, irradiates the diffraction beam screening lens group 7 in a parallel light posture, performs order filtering screening on each order diffraction beam through the diffraction beam screening lens group 7, and obtains a plurality of groups of target order diffraction beams and transmits the target order diffraction beams to the second lens 32.
After the multiple groups of target order diffraction beams pass through the second lens 32, different order interference fringes are generated on the surface of the reference grating 4, grating marks with the same period as that of each formed order interference fringe are processed on the surface of the reference grating 4, and for each order interference fringe, the order interference fringe irradiates on the reference grating with the same period as that of the order interference fringe.
The alignment signal acquisition unit 5 is closely attached to each reference grating to acquire a periodic sinusoidal light intensity signal formed at the position of the corresponding reference grating by each level interference fringe, and transmits the periodic sinusoidal light intensity signal generated at each reference grating to the upper computer 6.
The upper computer 6 calculates the static alignment position of the sample to be tested through the received periodic sinusoidal light intensity signals generated at each reference grating.
In a specific implementation, the light source 1 in the present application may generate a laser with a wavelength of 532nm or 632.8 nm.
In another preferred embodiment, please refer to fig. 2, fig. 2 shows a second schematic structural diagram of a static alignment system according to an embodiment of the present application. As shown in fig. 2, the alignment system further comprises an entrance fiber 9, a collimator lens 10 and a focusing lens 11, which are arranged in sequence between the light source 1 and the rotating plate 2.
The incident optical fiber 9 may be a single-mode polarization maintaining optical fiber, the wavelength of the incident optical fiber 9 may be 532nm or 632.8nm, the collimating lens 10 and the focusing lens 11 are lens groups with positive optical power, and specifically, for the collimating lens 10 or the focusing lens 11, the incident optical fiber may be an aspheric lens with better spherical aberration correction, or a spherical lens group with better spherical aberration correction.
In an example, after light emitted from the light source 1 passes through the incident optical fiber 9, a beam of emergent light with a preset wavelength and a preset polarization state is emitted, the emergent light is converted into parallel light through the collimating lens 10 and is transmitted to the focusing lens 11, the parallel light passes through the focusing lens 11 and the rotating flat plate 2 and is converged on focal planes of the first lens 31 and the second lens 32, and a preset angle exists between a rotating shaft of the rotating flat plate 2 and the surface of the rotating flat plate 2.
In order to reduce the influence of interference effects caused by the lens group and the surface of the sample to be measured in the static alignment system on the alignment precision, in the application, the incident laser generated by the light source 1 can be subjected to phase modulation before entering the incident optical fiber 9, so as to reduce the parasitic light influence caused by unnecessary light beam interference.
The collimating lens 10 has a main function of collecting energy of outgoing light rays entering the optical fiber 9 and conducting parallel propagation, and the focusing lens 11 has a main function of converging incoming parallel light rays.
In another preferred embodiment, as shown in fig. 2, the diffraction beam screening lens group 7 includes a reflecting prism 71 and an order diaphragm 72, wherein the reflecting prism 71 is disposed at a pupil plane of the focusing lens, a plurality of light passing holes for screening the diffraction beam of the preset order are preset on the order diaphragm, the position of the reflecting prism 71 also belongs to a central common focal position of the 4F optical system, and the reflecting prism 71 is a reflecting prism with a perpendicular surface of a light incident angle.
Preferably, the incident light emitted from the light source 1 is converged on the reflecting prism 71 through the rotating flat plate 2, a light spot which performs circular motion along with the rotation modulation of the light beam is formed on the surface of the reflecting prism 71, the light spot which performs circular motion forms an illumination light beam through the reflection action of the reflecting prism 71 to be incident on the first lens 31, and after passing through the first lens 31, the incident light beam irradiates on the alignment mark on the surface of the sample 8 to be measured in a parallel light posture.
Specifically, for any rotation angle of the rotating flat plate 2, after the light spot formed by the incident light at the reflecting prism 71 is converged on the first lens 31 through the reflecting prism 71 and the order diaphragm 72, the outgoing light beam of the first lens 31 is approximately perpendicularly irradiated on the alignment mark on the surface of the sample 8 to be measured in a parallel light posture.
In the present application, the sample 8 to be measured may be a planar sample with a preset alignment mark, such as a silicon wafer, a silicon carbide wafer, etc., where the position and the size of each light-passing hole on the order diaphragm 72 are preset, so as to screen out a preset order diffraction beam for performing subsequent alignment calculation.
In one example, since the alignment mark on the surface of the sample 8 to be measured is a phase grating structure in the horizontal XY direction, the incident light irradiated on the surface of the alignment mark generates different orders of diffraction beams under the influence of the phase grating structure, wherein the orders of diffraction beam generated by the alignment mark under the irradiation of the incident light are ±1 st order to ±7 th order, and specifically, the diffraction order corresponding to the diffraction beam can be determined by the following formula:
P sin(θ-θ 0 )＝kλ
in the formula, P represents an alignment mark period, θ is a diffraction beam exit angle, θ 0 In order to obtain the incident angle of the incident light to the alignment mark, k is the diffraction order corresponding to the diffracted light beam, λ is the wavelength of the incident light to the alignment mark, and it is known from the formula that θ and θ are given when the period of the alignment mark and the wavelength λ of the incident light are fixed 0 Together determine the diffraction orders of the diffracted beam.
Therefore, in the present application, due to the continuous rotation of the rotating plate, the light intensity and the incident angle of the incident light beam incident on the surface of the sample to be measured are actually changed continuously, so that different diffraction light beams can be obtained.
In a preferred embodiment, when each order diffracted beam passing through the first lens 31 passes through the order diaphragm 72, the plurality of light passing holes on the order diaphragm 72 filter and screen each order diffracted beam to obtain a plurality of groups of target order diffracted beams, and the plurality of groups of target order diffracted beams are incident on the second lens 32.
In this application, the original beam propagation direction of the multiple groups of diffraction beams is changed under the action of the first lens 31, the multiple groups of diffraction beams propagate to the order diaphragm 72 in an approximately parallel gesture, when passing through the order diaphragm 72, each order of diffraction beams is subjected to the action of multiple light passing holes on the order diaphragm 72, the higher order beams unnecessary in subsequent alignment calculation are selectively intercepted, only the multiple groups of target order diffraction beams in the XY direction required in the subsequent process are reserved to enter the subsequent light path for propagation, that is, the multiple light passing holes preset on the order diaphragm 72 in this application determine the diffraction orders allowed to pass.
In another preferred embodiment, the diffractive beam screening lens group 7 further includes an order separating component 73 disposed between the second lens 32 and the reflecting prism 71, the order separating component 73 is formed by bonding multiple wedge angle combinations, the order separating component 73 can modulate the spatial propagation directions of multiple groups of target order diffracted beams, and after passing through the order separating component 73, the propagation directions of multiple groups of target order diffracted beams are different, for example: a 2-layer wedge can achieve 2^2 =4 diffraction orders of deflection, and a complex wedge layer can achieve more complex diffraction orders of deflection.
Preferably, the multiple groups of target order diffraction beams are deflected and separated by the order separation component 73 to light rays in different directions, so as to obtain multiple groups of target order diffraction beams propagating in different directions in space, each group of target order diffraction beams subjected to deflection and separation carries propagation angle information corresponding to the target order diffraction beams to be incident on the second lens 32, and the propagation angle information indicates the deflection angle of the target order diffraction beams propagating in space by the order separation component 73.
The deflection angles of the positive-order diffracted beams and the negative-order diffracted beams of the same order are the same, the deflection angles are obtained through an order separation component 73, the order separation component is arranged at the focal plane positions of the first lens 31 and the second lens 32, a plurality of groups of target-order diffracted beams pass through the second lens 32, and for the positive-order diffracted beams and the negative-order diffracted beams of the same order, the positive-order diffracted beams and the negative-order diffracted beams of the same order are subjected to coherent superposition interference on a reference grating, and different orders of interference fringes are generated on the surface of the reference grating.
In this application, since the deflection angles of the positive-order diffracted beam and the negative-order diffracted beam of the same order are the same, after passing through the second lens 32, the two positive-order diffracted beams and the negative-order diffracted beam of the same order perform coherent superposition interference at the focal plane of the second lens 32 to form interference fringes, and the periods of the interference fringes of different orders are different.
The alignment signal acquisition unit 5 includes a signal fiber (not shown) and a signal acquisition board (not shown) that are attached to each reference grating.
Wherein, for each reference grating:
the method comprises the steps of collecting periodic sinusoidal light intensity signals formed at the reference grating by utilizing a signal optical fiber which is tightly attached to the reference grating, sending the collected periodic sinusoidal light intensity signals to a signal collecting board card by utilizing the signal optical fiber, carrying out signal conversion, demodulation and amplification processing on the received periodic sinusoidal light intensity signals collected by the reference grating by utilizing the signal collecting board card (OADB), transmitting the processed periodic sinusoidal light intensity signals to an upper computer, and completing static position alignment of a sample to be tested based on the periodic sinusoidal light intensity signals processed by utilizing a preset algorithm by utilizing the upper computer.
The signal conversion may be that the optical signal is converted into an analog signal and then into a digital signal.
In the application, the reference grating 4 is processed with a reference grating with the same period as each formed level interference fringe, and along with the continuous rotation of the follow-up rotating flat plate 2, each level interference fringe moves along the original fringe direction, a corresponding periodic sinusoidal light intensity signal is formed after passing through the reference grating with the same period, the periodic sinusoidal light intensity signal is tightly attached to a follow-up signal optical fiber of the reference grating to be collected, the collected periodic sinusoidal light intensity signal is transmitted to a rear signal acquisition board card, is processed by the signal acquisition board card and then is transmitted to an upper computer 6, and the periodic sinusoidal light intensity signal after corresponding processing of each reference grating is calculated by a preset algorithm integrated in the upper computer 6, so that the position information of the current alignment mark is obtained, and the alignment of the mark position is realized.
In another preferred embodiment of the present application, please refer to fig. 3, fig. 3 shows a third schematic structural diagram of a static alignment system according to an embodiment of the present application. As shown in fig. 3, the static alignment system further includes a polarization beam splitter group 13 disposed between the order stop 72 and the first lens 31.
Referring to fig. 4, fig. 4 shows a fourth schematic structural diagram of a static alignment system according to an embodiment of the present application. As shown in fig. 4, the static alignment system further includes another alignment subsystem B having the same structure as the alignment subsystem a, as shown in fig. 4, the alignment subsystem a and the alignment subsystem B are located at two sides of the polarization beam splitting surface corresponding to the polarization beam splitter group, and incident light beams emitted by the two alignment subsystems have different corresponding wavelengths.
In the present application, the optical path and the light transmission manner corresponding to the alignment subsystem B are identical to those of the alignment subsystem a, which are not described herein, but the wavelengths corresponding to the transmitted incident light beams are different according to the actual requirements.
Wherein for each alignment subsystem: the incident light beams passing through the secondary diaphragm 72 are incident to the polarization beam splitter group 13, the polarization beam splitter group 13 combines the incident light beams with two different wavelengths and linear polarization states from the two alignment subsystems at the alignment mark according to the polarization states corresponding to the two alignment subsystems, the polarized light beams after the beam combination are reflected to the first lens 31, are incident to the polarization beam splitter group 13 through the first lens 31, and the polarization beam splitter group 13 is used for splitting, and the obtained two incident light beams are respectively incident to the corresponding alignment systems so as to realize the static alignment of the dual-wavelength phase grating through the subsequent light paths.
The transmission process of the subsequent light path of each alignment system is the same, and the above description is omitted here.
In one possible implementation, referring to fig. 5a, fig. 5a shows a schematic view of incidence of two light beams with different polarization states according to an embodiment of the present application. As shown in fig. 5a, the polarization beam splitter group 13 includes a polarization beam splitter prism 131.
When the polarization states corresponding to the incident light beams corresponding to the two alignment systems are different, the polarization states corresponding to the incident light beams are different:
as shown in fig. 5a, assuming that the incident light corresponding to the alignment system a is P polarized light and the incident light corresponding to the alignment system B is S polarized light, the incident light of the alignment system a directly enters the first lens 31 through the polarization splitting prism 131, the incident light S2 of the alignment system B cannot pass through the polarization splitting prism 131, and then enters the first lens 31 after being reflected by the polarization splitting prism 131, and the first lens 31 enters the sample 8 to be measured from the light beams of the alignment system a and the alignment system B after being combined.
Referring to fig. 5b, fig. 5b shows an outgoing schematic diagram of two light beams with different polarization states according to an embodiment of the present application. As shown in fig. 5B, the polarized light after beam combination is reflected to the first lens 31, is incident to the polarizing beam splitter prism 131 through the first lens 31, and is split by the polarizing beam splitter prism 131, the P polarized light is returned to the alignment system a, the S polarized light is returned to the alignment system B, and then for each alignment system, the dual-wavelength phase grating static alignment is realized through the subsequent optical path.
The polarization beam splitter group 13 further includes a 1/4 wave plate 132 and a mirror 133.
In one possible implementation, referring to fig. 6a, fig. 6a shows one of the incident schematic diagrams of two light beams with the same polarization state provided in the embodiment of the present application. When the polarization states corresponding to the incident light beams corresponding to the two alignment systems are the same:
as shown in fig. 6a, assuming that the incident light beams corresponding to the alignment system a and the alignment system B are S polarized light, the incident light beam of the alignment system a passes through the polarization splitting prism 131, is reflected by the polarization splitting prism 131, and is incident on the reflecting mirror 133 through the 1/4 wave plate 132.
Referring to fig. 6b, fig. 6b shows a second schematic incident view of two light beams with the same polarization state according to the embodiment of the present application. As shown in fig. 6B, the reflection mirror 133 reflects the incident beam to the 1/4 wave plate 132,1/4 wave plate 132 to convert the S polarized light into P polarized light, and then the P polarized light is incident on the polarized incidence surface of the polarization splitting prism 131, and directly passes through the polarized incidence surface to reach the first lens 31, so that the incident beam of the alignment system B cannot pass through the polarized incidence surface of the polarization splitting prism 131, and is reflected at the polarized incidence surface, and then enters the first lens 31, and the light beams from the alignment systems a and B enter the beam combination and then enter the sample 8 to be measured by the first lens 31.
As shown in fig. 6B, the polarized light after beam combination is reflected to the first lens 31, is incident to the polarizing beam splitter prism 131 through the first lens 31, and is split by the polarizing beam splitter prism 131, the P polarized light is returned to the alignment system a, the S polarized light is returned to the alignment system B, and then for each alignment system, the dual-wavelength phase grating static alignment is realized through the subsequent optical path.
Referring to fig. 6c, fig. 6c shows an outgoing schematic diagram of two light beams with the same polarization state according to an embodiment of the present application. As shown in fig. 6c, the polarized light after beam combination is reflected to the first lens 31, enters the polarized incident surface of the polarization beam splitter prism 131 through the first lens 31, is split again by the polarization beam splitter prism 131, enters the 1/4 wave plate 132 through the polarization beam splitter prism 131, enters the reflecting mirror 133 after passing through the 1/4 wave plate 132, and then the reflecting mirror 133 reflects the light beam again to the 1/4 wave plate 132,1/4 wave plate 132 to convert the P polarized light into the S polarized light, and enters the polarized reflecting surface of the polarization beam splitter prism 131, is refracted by the polarized reflecting surface and returns to the alignment system a.
The S-polarized light incident on the polarization beam splitter 131 through the first lens 31 is directly refracted by the polarization reflecting surface and returned to the alignment system B.
In the application, different alignment subsystems generate incident light rays with different wavelengths and different polarization states, and after the polarization splitting prism 13 is added, the static alignment of the dual-wavelength phase grating can be realized.
The static alignment system adopts a phase grating static alignment system, and is different from the traditional dynamic scanning phase grating static alignment system, and the rotation flat plate is added to perform an angle dynamic modulation on the illumination beam, so that the position diffraction information of the alignment mark can be synchronously obtained without the displacement of the alignment mark, the effect of static scanning is realized, and the alignment precision and efficiency are improved.
Based on the same application conception, the embodiment of the application also provides an alignment method corresponding to the static alignment system based on the phase grating provided by the embodiment, wherein the method comprises the following steps:
the upper computer drives the rotating flat plate to rotate through the rotating motor, and incident light rays emitted by the light source irradiate on an alignment mark on the surface of the sample to be detected through the rotating flat plate, the diffraction beam screening lens group and the first lens at a variable incident angle;
the alignment mark diffracts each order diffraction beam with brightness change outwards under the effect of incident light with continuously changing incident angle, each order diffraction beam passes through the first lens, irradiates the diffraction beam screening lens group in parallel light gesture, filters and screens each order diffraction beam through the diffraction beam screening lens group to obtain a plurality of groups of target order diffraction beams and transmits the target order diffraction beams to the second lens;
After the multiple groups of target order diffraction beams pass through the second lens, different orders of interference fringes are generated on the surface of the reference grating under the action of the second lens, grating marks with the same period as each formed order of interference fringes are processed on the surface of the reference grating, and each order of interference fringe irradiates on the reference grating with the same period as the corresponding order of interference fringe;
the alignment signal acquisition unit is tightly attached to each reference grating to acquire periodic sinusoidal light intensity signals formed by each level interference fringe at the position corresponding to the reference grating under the action of the motion of the rotating flat plate, and transmits the periodic sinusoidal light intensity signals corresponding to the level interference fringes to the upper computer, so that the calculation of the alignment position of the sample to be detected is realized through the upper computer.
It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described system and apparatus may refer to corresponding procedures in the foregoing method embodiments, which are not described herein again. In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. The above-described apparatus embodiments are merely illustrative, for example, the division of the units is merely a logical function division, and there may be other manners of division in actual implementation, and for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be through some communication interface, device or unit indirect coupling or communication connection, which may be in electrical, mechanical or other form.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a non-volatile computer readable storage medium executable by a processor. Based on such understanding, the technical solutions of the present application may be embodied in essence or a part contributing to the prior art or a part of the technical solutions, or in the form of a software product, which is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
The foregoing is merely a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present application, and the changes or substitutions are covered in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (10)
1. A static alignment system based on a phase grating is characterized by comprising an alignment subsystem, a first lens and an upper computer, wherein the alignment subsystem comprises a light source, a rotating flat plate, a second lens, a reference grating, an alignment signal acquisition unit and a diffraction beam screening lens group arranged between the first lens and the second lens,
the rotating flat plate is arranged on a rotating motor which is driven and controlled by the upper computer so that the upper computer drives the rotating flat plate to rotate,
wherein, the incident light emitted from the light source irradiates the diffraction beam screening lens group after generating light deflection through the rotating flat plate, the incident light irradiates an alignment mark on the surface of the sample to be detected through the diffraction beam screening lens group and the first lens in sequence, the alignment mark is a phase grating structure in the horizontal XY direction,
The alignment mark diffracts each order diffraction beam carrying position information in the XY direction under the action of the incident light, each order diffraction beam passes through a first lens and irradiates the diffraction beam screening lens group in a parallel light posture, each order diffraction beam is subjected to order filtering screening through the diffraction beam screening lens group, and a plurality of groups of target order diffraction beams are obtained and transmitted to the second lens;
generating different orders of interference fringes on the surface of the reference grating after the multiple groups of target orders of diffraction beams pass through the second lens, wherein grating marks with the same period as that of each formed order of interference fringe are processed on the surface of the reference grating, and the orders of interference fringes irradiate the reference grating with the same period as that of each formed order of interference fringe;
the alignment signal acquisition unit is tightly attached to each reference grating to acquire periodic sinusoidal light intensity signals formed by each level interference fringe at the position corresponding to the reference grating, and transmits the periodic sinusoidal light intensity signals corresponding to each level interference fringe to the upper computer;
the upper computer utilizes periodic sinusoidal light intensity signals generated at each reference grating to realize the calculation of the static alignment position of the sample to be detected.
2. The static alignment system according to claim 1, further comprising an incident optical fiber, a collimating lens and a focusing lens disposed in sequence between said light source and said rotating plate, said collimating lens and said focusing lens each being a lens group having positive optical power, said incident optical fiber being a single mode polarization maintaining fiber,
after passing through the incident optical fiber, the light emitted from the light source emits an outgoing light beam with preset wavelength and preset polarization state;
the emergent light is converted into parallel light through the collimating lens and is transmitted to the focusing lens;
the parallel light rays sequentially pass through the focusing lens and the rotating flat plate and are converged on focal planes of the first lens and the second lens.
3. The static alignment system according to claim 2, wherein the diffraction beam screening lens group comprises a reflecting prism and an order diaphragm, the reflecting prism is disposed at a pupil plane of the focusing lens, the order diaphragm is provided with a plurality of light passing holes for screening the diffraction beam of the preset order in advance,
the incident light rays emitted from the light source pass through the rotating flat plate and are converged on the reflecting prism, and light spots which perform circular motion along with the rotation modulation of the light beams are formed on the surface of the reflecting prism;
The light spots performing circular motion form illumination light beams to be incident to the first lens under the reflection effect of the reflecting prism;
after passing through the first lens, the incident light irradiates on an alignment mark on the surface of the sample to be detected in a parallel light posture.
4. A static alignment system according to claim 3, wherein each order diffracted beam passing through a first lens is filtered by a plurality of light passing holes on the order stop when passing through the order stop, so as to obtain a plurality of groups of target order diffracted beams, and the plurality of groups of target order diffracted beams are irradiated to the second lens.
5. The static alignment system according to claim 4, wherein said diffractive beam screening lens group further comprises a step separation assembly disposed between said second lens and said reflective prism, said step separation assembly being bonded by a plurality of wedge angle combinations,
the multi-group target order diffraction light beams are deflected and separated to different directions by the order separation assembly, so that multi-group target order diffraction light beams which are transmitted to different directions in space are obtained;
each group of target order diffraction light beams after deflection separation is incident to the second lens with propagation angle information corresponding to the target order diffraction light beams, and the propagation angle information indicates the deflection angle of the target order diffraction light beams propagated to space by the order separation component.
6. The static alignment system according to claim 5, wherein the same order of positive and negative diffracted beams are deflected by the same angle through the order splitting assembly, the order splitting assembly being disposed at the focal plane positions of the first and second lenses,
and for the positive-order diffraction light beams and the negative-order diffraction light beams of the same order, the positive-and negative-order light beams of the same order are subjected to coherent superposition interference on the reference grating, and different orders of interference fringes are generated on the surface of the reference grating.
7. The static alignment system according to claim 3, wherein the static alignment system of the phase grating further comprises another alignment subsystem having the same structure as the alignment subsystem, the alignment system further comprises a polarization beam splitter group disposed between the secondary diaphragm and the first lens, the two alignment subsystems are disposed on two sides of the polarization beam splitter surface corresponding to the polarization beam splitter group, the incident light beams emitted by the two alignment subsystems have different corresponding wavelengths,
wherein for each alignment subsystem: the incident light beam passing through the secondary diaphragm is incident to the polarization spectroscope group;
The polarization beam splitter group combines the incident light beams which come from the two alignment subsystems, have two different wavelengths and have linear polarization states at the polarization beam splitter prism according to the polarization states corresponding to the two alignment subsystems;
the polarized light after beam combination is incident to the first lens, is diffracted and split by the alignment mark, and then is incident to the polarized spectroscope group through the first lens again, the polarized spectroscope group splits the beam, and the two obtained incident light beams are respectively incident to the corresponding alignment system so as to realize the static alignment of the dual-wavelength phase grating through the subsequent light path.
8. The static alignment system of claim 7, wherein the axis of rotation of the rotating plate is at a predetermined angle to the surface of the rotating plate.
9. The static alignment system of claim 1 wherein said alignment signal acquisition unit comprises a signal fiber and signal acquisition board affixed to each reference grating,
wherein, for each reference grating:
the method comprises the steps that a signal optical fiber clung to a reference grating is used for collecting periodic sinusoidal light intensity signals formed at the reference grating, and the collected periodic sinusoidal light intensity signals are sent to a signal collecting board card by the signal optical fiber;
The signal acquisition board card performs signal conversion, demodulation and amplification processing on the received periodic sinusoidal light intensity signals acquired by the reference grating, and transmits the processed periodic sinusoidal light intensity signals to the upper computer;
and the upper computer finishes the static position alignment of the sample to be detected by using a preset algorithm based on the processed periodic sinusoidal light intensity signals corresponding to each reference grating.
10. An alignment method applied to the phase grating based static alignment system of any one of claims 1-9, the method comprising:
the upper computer drives the rotating flat plate to rotate through the rotating motor;
the incident light emitted by the light source irradiates on an alignment mark on the surface of the sample to be detected through the rotating flat plate, the diffraction beam screening lens group and the first lens at a variable incident angle, the alignment mark is a phase grating structure mark in the horizontal XY direction,
the alignment mark diffracts each order diffraction beam carrying position information outwards under the action of the incident light with the continuously changing incident angle, each order diffraction beam passes through a first lens and irradiates to the diffraction beam screening lens group in a parallel light posture, each order diffraction beam is filtered and screened by the diffraction beam screening lens group, and a plurality of groups of target order diffraction beams are obtained and transmitted to the second lens;
After the multiple groups of target order diffraction beams pass through the second lens, different orders of interference fringes are generated on the surface of the reference grating under the action of the second lens, grating marks with the same period as each formed order of interference fringes are processed on the surface of the reference grating, and each order of interference fringe irradiates a reference grating with the same period as the corresponding order of interference fringe;
the alignment signal acquisition units are tightly attached to the reference gratings to acquire periodic sinusoidal light intensity signals formed by transmission of each level interference fringe at the corresponding reference grating under the action of the motion of the rotating flat plate, and the periodic sinusoidal light intensity signals corresponding to the level interference fringes are transmitted to the upper computer to realize the calculation of the static alignment position of the sample to be detected through the upper computer.
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