CN101566800B - Aligning system and aligning method for lithography equipment - Google Patents
Aligning system and aligning method for lithography equipment Download PDFInfo
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Abstract
The invention provides an aligning system and an aligning method for a lithography equipment, which adopts two or more groups of amplitude-type reference grating and aligning marks of different periods; each branch grating of the reference grating and the aligning marks consist of bar-shaped structures with equidifferent arrangement widths so as to lead the scanning intensity signal peak to be sharper and improve the reliability of the aligning system; during the aligning process, only (plus and minus) 1 stage of diffracted beam with aligned marks is used; after the small period grating coherent image and corresponding reference gratings in the aligned marks are scanned, the obtained scanning signal intensity peak is used as coarse capture; based on coarse capture, the precise capture information is obtained by the phase information of the large period grating coherent images in the aligned marks; furthermore, the phase information obtained by scanning the large period grating coherentimage and the corresponding reference grating in the aligned marks is used for precise alignment; and the alignment position error caused by asymmetric deformation of the alignment marks is reduced, the complexity of the optical system is reduced and the utilization ratio of the optical energy is improved.
Description
Technical field
The present invention relates to lithographic equipment, relate in particular to a kind of alignment system and alignment methods that is used for lithographic equipment.
Background technology
Lithographic equipment of the prior art is mainly used in the manufacturing of integrated circuit (IC) or other microdevices.By lithographic equipment, the multilayer mask with different mask patterns under accurate alignment case successively exposure image be coated with on the silicon chip of photoresist.Present lithographic equipment is divided into two classes substantially, one class is the stepping lithographic equipment, the mask pattern single exposure is imaged on an exposure area of silicon chip, silicon chip moves with respect to mask subsequently, next exposure area is moved to mask pattern and projection objective below, again mask pattern is exposed in another exposure area of silicon chip, repeat the picture that this process all exposure areas on silicon chip all have corresponding mask patterns.Another kind of is the step-scan lithographic equipment, and in said process, mask pattern is not the single exposure imaging, but the scanning mobile imaging by the projection light field.In the mask pattern imaging process, mask and silicon chip move with respect to optical projection system and projected light beam simultaneously, finish silicon wafer exposure.
Critical step is that mask is aimed at silicon chip in the lithographic equipment.After exposing on silicon chip, the ground floor mask pattern removes in the slave unit, after the PROCESS FOR TREATMENT that silicon chip is correlated with, carry out the exposure of second layer mask pattern, but for guarantee second layer mask pattern and subsequently the picture of mask pattern mask and silicon chip accurately need be aimed at respect to the accurate location of exposed mask pattern image on the silicon chip.Because the IC device of photoetching technique manufacturing needs multiexposure, multiple exposure to form multilayer circuit in silicon chip, for this reason, require to realize the accurate aligning of mask and silicon chip in the lithographic equipment.When characteristic dimension requires more hour, will become strict more to the requirement of alignment precision.
Prior art has two kinds of alignment scheme, a kind of is the TTL technique of alignment that sees through camera lens, alignment mark on the laser lighting mask images in the silicon chip plane by object lens, mobile silicon chip platform, make the reference marker scanning alignment mark imaging on the silicon chip platform, the light intensity of the imaging of sampling simultaneously, correct alignment position is promptly represented in the largest light intensity position of detector output, described aligned position provides zero reference for the position measurement of the laser interferometer that is used for monitoring wafer platform position and moves.Another kind is an OA off-axis alignment technology, is positioned at the reference mark of datum plate on a plurality of alignment marks on the silicon chip platform and the silicon chip platform by the off-axis alignment systematic survey, realizes that silicon chip is aimed at and silicon chip platform aligning; Reference marker is aimed at mask alignment mark on the silicon chip platform, realizes mask registration; Can obtain the position relation of mask and silicon chip thus, realize mask and silicon chip aligning.
At present, the most alignment so that adopts of lithographic equipment is a grating alignment.Grating alignment is meant that illumination beam on the grating type alignment mark diffraction takes place, the full detail multilevel diffraction light that diffraction light carries about alignment mark structure scatters from the phase alignment grating with different angles, after filtering zero order light by spatial filter, gather ± 1 order diffraction light, the perhaps raising that requires along with CD, gather multi-level diffraction light (comprising senior) simultaneously at the reference surface interference imaging, utilize picture to scan at certain orientation with reference to grating with corresponding, survey and signal Processing through photodetector, determine the centering adjustment position.
Literature search through prior art is found, Chinese patent open (bulletin) number adopts a kind of ATHENA off-axis alignment system of 4f system architecture for the Dutch ASML of the patent of CN1506768A " alignment system and the method that are used for etching system " company, and described alignment system adopts ruddiness, green glow two-source illumination at the Lights section; And adopt voussoir array or wedge group to realize the overlapping and coherent imaging of alignment mark multi-level diffraction light, and on image planes, imaging space is separated; The registration signal of ruddiness and green glow is separated by a polarization beam splitter prism; By surveying the alignment mark picture, obtain the registration signal of sinusoidal output through transmitted light intensity with reference to grating.Described alignment system is by surveying the aligned position error that (comprising diffraction light senior time), the multilevel diffraction light caused to reduce the alignment mark asymmetrical deformation of alignment mark.The concrete corresponding overlapping coherent imaging of positive and negative level time hot spot that adopts voussoir array or wedge group to realize the alignment mark multi-level diffraction light, the deviation of diffraction light light beams at different levels by voussoir array or wedge group makes alignment mark be used for the grating grating pictures at different levels that the x direction aims at and is arranged in picture in image planes along the y direction simultaneously; The grating grating pictures at different levels that are used for y direction aligning are arranged in picture in image planes along the x direction, and different cycles grating picture scans a situation with reference to grating, the cross-interference issue of effective address signal simultaneously when having avoided alignment mark grating pictures scanning at different levels correspondence with reference to grating.But when using wedge to determine array, the face type and the angle of wedge coherence request of two voussoirs that the positive and negative same stages of birefringence is inferior are very high; And the requirement of the processing and manufacturing of wedge group, assembling and adjustment is also very high, and the specific implementation engineering difficulty of getting up is bigger, costs dearly.
Further, Chinese patent open (bulletin) number is 200710044152.1 patent " a kind of alignment system that is used for lithographic equipment ", described alignment system adopts has three periods phase grating of thickness combination, the first-order diffraction light that only utilizes these three cycles is as registration signal, obtain high alignment precision when can realize big capture range, only use the first-order diffraction light in each cycle, can obtain stronger signal intensity, improve system signal noise ratio, need not come separately senior diffraction components of multichannel by regulating devices such as wedges, simplify light path design and debugging difficulty, but alignment mark distribution in one line on silicon chip and datum plate in the alignment system, reduced the utilization factor of light source, and when this arrangement mode alignment mark in alignment scanning is respectively organized grating picture scanning correspondence with reference to grating, the grating picture of different cycles scans a situation with reference to grating simultaneously, can cause the cross-interference issue of sweep signal, is unfavorable for the aligning of lithographic equipment.
Summary of the invention
The object of the present invention is to provide a kind of alignment system and alignment methods that is used for lithographic equipment,, improve the reliability of alignment system so that scanning strength signal peak value is more sharp-pointed.
In order to realize above-mentioned purpose, the invention provides a kind of alignment system that is used for lithographic equipment, comprising: aim at radiation source module, be provided for the radiation source of alignment system; Lighting module transmits the radiation source of described aligning radiation source module, the alignment mark on collimated illumination silicon chip or the datum plate; The alignment optical module, gather the diffracted beam of alignment mark corresponding stage time and coherent imaging at amplitude type with reference to stop position; And acquisition of signal module, it comprises: amplitude type is with reference to grating, detector and signal processing, coherent imaging by the alignment mark diffracted beam and respective amplitudes type are surveyed and are handled through the aligning light intensity signal of amplitude type with reference to Grating Modulation with reference to the scanning of grating; Described amplitude type comprises the grating of two groups or more different cycles with reference to grating, and described amplitude type is a diamond structure with reference to each branch's grating of grating, and it is made up of the strip structure that big gradually little equal difference is arranged from the centre to both sides width; Described alignment mark comprises the grating of two groups or more different cycles, and each branch's grating of described alignment mark is a diamond structure, and it is made up of the strip structure that big gradually little equal difference is arranged from the centre to both sides width.
Further, described amplitude type comprises directions X first grating, directions X second grating that is arranged in order along directions X with reference to grating; Y direction first grating, Y direction second grating that are arranged in order along the Y direction; Described directions X first grating, described directions X second grating, described Y direction first grating, described Y direction second grating are distinguished corresponding with each branch's grating of described alignment mark; Described amplitude type looks like to scan to corresponding alignment mark grating interference respectively with reference to grating, obtains directions X second sweep signal, directions X first sweep signal, directions X the 3rd sweep signal, Y direction second sweep signal, Y direction first sweep signal and Y direction the 3rd sweep signal.
Further, described amplitude type exchanges as required or moves with reference to branch's grating relative position of grating.Further, comprise laser cell in the described aligning radiation source module.
Further, described laser cell comprises phase-modulator and intensity modulator unit.
Further, described laser cell comprises laser instrument, and described laser instrument is gas laser, solid state laser, semiconductor laser or fiber laser.
Further, described alignment optical module comprises alignment optical system and light-dividing device.
Further, described light-dividing device utilizes the separately alignment of two kinds of different wave lengths of polarisation of light character.
The present invention also provides a kind of alignment methods that is used for optical device of using described system, by the less periodic optical grating in the alignment mark is scanned, obtain first sweep signal and the 3rd sweep signal, by in the alignment mark than the large period raster scanning, obtain second sweep signal; Utilize the phase information of the first sweep signal intensity peak information capture, second sweep signal to obtain thick catch position, utilize the phase information of second sweep signal to catch the phase information of the sweep signal of winning the third place, utilize the phase information of the 3rd sweep signal to carry out fine alignment.
Further, described alignment methods comprises the steps: that specifically aiming at radiation source irradiates through the lighting module transmission to described alignment mark diffraction takes place, utilize described alignment mark ± 1 order diffraction light beam through alignment optical module coherent imaging, and utilize the corresponding amplitude type of acquisition of signal module to obtain aiming at light intensity signal as carrying out signal intensity scanning with reference to the described alignment mark of grating pair is relevant, directions X first grating that wherein said amplitude type is arranged along directions X with reference to grating and the relevant picture scanning of the corresponding grating with the directions X alignment mark of directions X second grating obtain directions X and aim at light intensity signal, and Y direction first grating that described amplitude type is arranged along the Y direction with reference to grating and Y direction second grating and the corresponding grating of Y direction alignment mark are concerned with and obtain the Y direction and aim at light intensity signal as scanning; The described aligning light intensity signal that obtains is connected described amplitude type and will aims at light intensity signal with reference to the Transmission Fibers of grating back and be transferred to the photodetector that is connected with Transmission Fibers and survey through accurate; Utilize described photodetector to survey the intensity and the phase information that obtain described aligning light intensity signal and carry out position sensing and aligning, by the less periodic optical grating in the described alignment mark is scanned, obtain described first sweep signal and described the 3rd sweep signal, by in the described alignment mark than the large period raster scanning, obtain described second sweep signal; Utilize the phase information of described second sweep signal of the described first sweep signal intensity peak information capture to obtain thick catch position, utilize the phase information of described second sweep signal to catch the phase information of described the 3rd sweep signal, utilize the phase information of described the 3rd sweep signal to carry out fine alignment.
Further, described amplitude type is a diamond structure with reference to each branch's grating of grating, and it is made up of the strip structure that big gradually little equal difference is arranged from the centre to both sides width.
Further, each branch's grating of described alignment mark is a diamond structure, and it is made up of the strip structure that big gradually little equal difference is arranged from the centre to both sides width.
Further, described amplitude type comprises directions X first grating, directions X second grating that is arranged in order along directions X with reference to grating; Y direction first grating, Y direction second grating that are arranged in order along the Y direction; Described directions X first grating, described directions X second grating, described Y direction first grating, described Y direction second grating are distinguished corresponding with each branch's grating of described alignment mark; Described amplitude type looks like to scan to corresponding alignment mark grating interference respectively with reference to grating, obtains directions X second sweep signal, directions X first sweep signal, directions X the 3rd sweep signal, Y direction second sweep signal, Y direction first sweep signal and Y direction the 3rd sweep signal.
Further, described amplitude type exchanges as required or moves with reference to branch's grating relative position of grating.
In sum, the present invention has adopted the amplitude type of two groups or more different cycles with reference to grating and alignment mark, described each branch's grating with reference to grating and described alignment mark is made up of the strip structure of width equal difference arrangement, can make scanning strength signal peak value more sharp-pointed, improved the reliability of alignment system, only use in the alignment procedures alignment mark ± 1 order diffraction light beam, less periodic optical grating in the alignment mark is relevant to be looked like with corresponding with reference to behind the raster scanning, the sweep signal intensity peak that utilization obtains is as slightly catching, obtain smart capturing information slightly catching the phase information that utilizes on the basis in the alignment mark than the relevant picture of large period grating, and it is relevant as being used for fine alignment with the corresponding phase information that obtains with reference to raster scanning in conjunction with the less periodic optical grating in the alignment mark, reduced the aligned position error that the alignment mark asymmetrical deformation causes, reduce the complicacy of optical system, improved the efficiency of light energy utilization.
Description of drawings
Fig. 1 is the used alignment system of lithographic equipment of the present invention and the total arrangement between the lithographic equipment, principle of work structural representation;
Fig. 2 is the used alignment system structural representation of embodiment of the present invention;
Fig. 3 is the used alignment system intermediate frequency spectrum of an embodiment of the present invention face filtering pore size distribution synoptic diagram;
Fig. 4 is the synoptic diagram of first embodiment of the invention with reference to grating;
Fig. 5 is the synoptic diagram of first embodiment of the invention alignment mark;
Fig. 6 is the synoptic diagram of the corresponding sweep signal of first embodiment of the invention;
Fig. 7 is the synoptic diagram of second embodiment of the invention with reference to grating;
Fig. 8 is the synoptic diagram of second embodiment of the invention alignment mark;
Fig. 9 is the synoptic diagram of the corresponding sweep signal of second embodiment of the invention.
Embodiment
Below in conjunction with accompanying drawing and specific embodiments alignment system that is used for lithographic equipment and the alignment methods that the present invention proposes is described in further detail.
Please refer to Fig. 1, it is the alignment system of the used lithographic equipment of the present invention and the total arrangement between the lithographic equipment, principle of work structural representation.The formation of described lithographic equipment comprises: the illuminator 1 that is used to provide exposing light beam; Be used to support the mask holder and the mask platform 3 of mask 2, the alignment mark RM that mask pattern is arranged on the mask 2 and have periodic structure; Be used for the mask pattern on the mask 2 is projected to the projection optical system 4 of silicon chip 6; Be used to support the silicon chip support and the silicon chip platform 7 of silicon chip 6, the datum plate 8 that is carved with reference mark FM is arranged on the silicon chip platform 7, the alignment mark of periodicity optical structure is arranged on the silicon chip 6; Be used for the off-axis alignment system 5 that mask and silicon chip are aimed at; The catoptron 10,16 and the laser interferometer 11,15 that are used for mask platform 3 and 7 position measurements of silicon chip platform, and by the mask platform 3 of master control system 12 controls and the servo-drive system 13 and the drive system 9,14 of silicon chip platform 7 displacements.
Wherein, illuminator 1 comprises that a light source, one make the lens combination of illumination homogenising, catoptron, a condenser (all not shown among the figure).As a light source cell, adopt KrF excimer laser (wavelength 248nm), ArF excimer laser (wavelength 193nm), F2 laser instrument (wavelength 157nm), Kr2 laser instrument (wavelength 146nm), Ar2 laser instrument (wavelength 126nm) or use ultrahigh pressure mercury lamp (g-line, i-line) etc.The exposing light beam IL of illuminator 1 uniform irradiation is radiated on the mask 2, includes the mark RM of mask pattern and periodic structure on the mask 2, is used for mask registration.Mask platform 3 can move in perpendicular to the X-Y plane of illuminator optical axis (overlapping with the optical axis AX of projection objective) through drive system 14, and moves with specific sweep velocity in predetermined direction of scanning (being parallel to X-direction).The position of mask platform 3 in plane of motion recorded by Doppler's two-frequency laser interferometer 15 precisions by the catoptron 16 that is positioned on the mask platform 3.The positional information of mask platform 3 sends to master control system 12 by laser interferometer 15 through servo-drive system 13, and master control system 12 drives mask platform 3 according to the positional information of mask platform 3 by drive system 14.
Projection optical system 4 (projection objective) is positioned at mask platform shown in Figure 13 belows, and its optical axis AX is parallel to Z-direction.Since adopt two core structures far away and have predetermined scale down as 1/5 or 1/4 tear the formula of penetrating or refractive and reflective optical system open as projection optical system, so when the mask pattern on the exposing light beam illuminating mask 2 of illuminator 1 emission, the image that the circuit mask pattern becomes to dwindle on the silicon chip 6 that is coated with photoresist through projection optical system.
Silicon chip platform 7 is positioned at the below of projection optical system 4, and silicon chip platform 7 is provided with a silicon chip support (not shown), and silicon chip 6 is fixed on the support.Silicon chip platform 7 through drive system 9 drive can be in the direction of scanning (directions X) and go up motion perpendicular to direction of scanning (Y direction), make the zones of different of silicon chip 6 to be positioned in the exposure light field, and carry out the step-scan operation.The position of silicon chip platform 7 in X-Y plane recorded by Doppler's two-frequency laser interferometer 11 precisions by a catoptron 10 that is positioned on the silicon chip platform, the positional information of silicon chip platform 7 sends to master control system 12 through servo-drive system 13, and master control system 12 is according to the motion of positional information (or velocity information) by drive system 9 control silicon chip platforms 7.
Silicon chip 6 is provided with the alignment mark of periodic structure, and the datum plate 8 that comprises reference mark FM is arranged on the silicon chip platform 7, and alignment system 5 realizes that by silicon chip alignment mark and reference mark FM silicon chip 6 is aimed at and silicon chip platform 7 is aimed at respectively.In addition, coaxial alignment unit (not shown) is aimed at the reference mark FM of datum plate 8 on the silicon chip platform with mask alignment mark RM, realizes mask registration.The alignment information of alignment system 5 is transferred to master control system 12 together in conjunction with the alignment information of coaxial alignment unit, and after data processing, drive system 9 drives silicon chip platform 7 and moves the aligning of realizing mask and silicon chip 6.
Please refer to Fig. 2, it is the alignment system structural representation of first embodiment of the invention, and described alignment system mainly is made up of light source module, lighting module, image-forming module, detecting module, signal Processing and locating module (not illustrating among the figure) etc.Light source module mainly comprises light source, shutter, optoisolator and the radio frequency modulator (not illustrating among the figure) that two wavelength are provided.Lighting module comprises Transmission Fibers and lamp optical system.Image-forming module mainly comprises: the object lens of large-numerical aperture (211), beam splitter 214, bi-directional beam divider 218, spatial filter (219,224) and lens combination (211,220,225).Detecting module comprises with reference to grating (221,226), Transmission Fibers (216,222,227), CCD camera 217 and photodetector (223,228).Signal Processing and locating module mainly comprise photosignal conversion and amplification, analog to digital conversion and digital signal processing circuit etc.
The alignment system principle is: the light beam 201 of light source module output (comprises two kinds of choosing wavelengths, also can use simultaneously) enter light beam bundling device 202, be transferred to the polarizer 204 via monofilm polarization maintaining optical fibre 203, lens 205, illuminating aperture diaphragm 206 and lens 207, reflecting prism 208 on dull and stereotyped 209 impinges perpendicularly on the object lens 211 that achromatic λ/4 wave plates 210 enter large-numerical aperture (4F lens preceding group) then, light beam is assembled through the object lens 211 of large-numerical aperture and is shone on the silicon chip mark 212 concurrent gaining interest and penetrate, 212 at different levels diffraction lights of mark return along former road and enter beam splitter 214 through dull and stereotyped 209, beam splitter 214 reflexes to the CCD light path through lens 215 with the sub-fraction diffraction light through plated film reflecting surface 213, Transmission Fibers 216, image in and be used for observing the picture situation that is marked as on the CCD217, another part diffraction light along the light path transmissive by 218 two kinds of wavelength light beams of Amici prism separately, enter different light paths respectively, through corresponding spatial filter (219,224) (what the present invention needed is respectively each grating ± 1 order diffraction light for the diffraction lighting level that select to need time, and scioptics system (220,225, back group of 4F lens) the corresponding order of diffraction time interference of light picture is become at reference grating (221,226) on, the mark order of diffraction time interference image is via reference grating (221,226) signal that obtains of scanning is through Transmission Fibers (222,227) be transported to photodetector (223,228) carry out acquisition of signal.
Please refer to Fig. 3, it is the structural representation of the used spatial filter of the present invention (219,224), is divided into vertical and horizontal both direction and arranges, and is respectively applied for the alignment mark ± 1 order diffraction light filtering of both direction.
Please continue with reference to figure 4 and Fig. 5, wherein Fig. 4 is with reference to the structure first embodiment synoptic diagram of grating among Fig. 1, Fig. 5 is the synoptic diagram of first embodiment of the invention alignment mark, as shown in the figure, comprise four groups of amplitude gratings with reference to grating 400, it is directions X first grating 401, directions X second grating 402, Y direction first grating 403 and Y direction second grating 404, directions X first grating 501 of the corresponding first embodiment alignment mark 500 of difference, directions X second grating 502 and Y direction first grating 503, Y direction second grating 504 is respectively applied for directions X and Y direction and aims at.Wherein, directions X first grating 401, directions X second grating 402, Y direction first grating 403 and Y direction second grating 404 are diamond structure, form by the strip structure that big gradually little equal difference is arranged from the centre to both sides by width, can make scanning strength signal peak value more sharp-pointed, improve the reliability of alignment system.Described four groups of amplitude types with reference to grating along the length of cycle direction can equal corresponding alignment mark grating ± length of 1 grade of grating picture, can also be greater than or less than the length of corresponding alignment mark grating ± 1 grade grating picture.Be respectively arranged with the Transmission Fibers bundle behind described four groups of amplitude gratings, comprise first Transmission Fibers 405, second Transmission Fibers 406, the 3rd Transmission Fibers 407 and the 4th Transmission Fibers 408, the described transmitted light of respectively organizing grating with reference to grating is transferred to the corresponding photo detector array, in reference grating 400 and alignment mark 500 scanning processes, obtain the alignment scanning signal of alignment mark X and Y direction.
As shown in Figure 5, alignment mark 500 is that dutycycle is 1: 1 a phase grating structure, alignment mark 500 comprises the grating of each two groups of different cycles of both direction: directions X first grating 501, directions X second grating 502, Y direction first grating 503 and Y direction second grating 504, directions X first grating 501 wherein, directions X second grating 502, Y direction first grating 503 and Y direction second grating 504 are diamond structure, form by the strip structure that big gradually little equal difference is arranged from the centre to both sides by width, the grating cycle of directions X first grating 501 and Y direction first grating 503 is P1, the grating cycle of directions X second grating 502 and Y direction second grating 504 is P2, and P2＜P1, the filtering hole of requirement on filtering face is merely able to allow grating separately ± 1 order diffraction light transmission, and other level time diffraction lights are owing to being blocked outside the filtering hole.Two groups of grating cycles of described alignment system alignment mark both direction can be according to the position of diffracted beam on frequency surface separately, carry out suitable cycle coupling, so that carry out spatial filtering, can produce registration signal with strong Technological adaptability, high sensitivity and high s/n ratio, the alignment system repeatability precision can reach 3～5nm, satisfy fully live width 90nm and 90nm following to alignment request.
As shown in Figure 6, utilize photodetector to survey the intensity and the phase information that obtain the alignment scanning signal and carry out position sensing and aligning, utilize the relevant picture of less periodic optical grating in the alignment mark and correspondingly scan with reference to grating, obtain the first sweep signal S1 and the 3rd sweep signal S3, utilize in the alignment mark than large period grating coherent phase and correspondingly scan with reference to grating, obtain the second sweep signal S2, utilize the phase information of surveying the first sweep signal S1 intensity peak information capture, the second sweep signal S2 that obtains to obtain thick catch position, the phase information that the phase information of the second sweep signal S2 that obtains is caught the sweep signal S3 that wins the third place is caught in utilization, utilizes the phase information of the 3rd sweep signal S3 to carry out fine registration.In the alignment procedures only with two groups of gratings ± 1 order diffraction light, reduced the complicacy of optical system, improved the efficiency of light energy utilization.Minor cycle grating in the alignment mark is relevant to be looked like with corresponding with reference to behind the raster scanning, the sweep signal intensity peak that utilization obtains is as slightly catching, utilize the phase information of the relevant picture of large period grating in the alignment mark to obtain smart capturing information on the basis slightly catching, and relevant in conjunction with the minor cycle grating in the alignment mark as being used for fine alignment with the corresponding phase information that obtains with reference to raster scanning, reduced the aligned position error that the alignment mark asymmetrical deformation causes.
Second embodiment of the present invention is to adopt the lithographic equipment of above-mentioned alignment system, its with reference to grating, alignment mark and sweep signal respectively referring to Fig. 7～Fig. 9.Its embodiment is identical with first embodiment, and has adopted corresponding label among the figure, so do not repeat them here.Need to prove that in other embodiment of the present invention, amplitude type can comprise also that with reference to grating the grating of different cycles more than two groups, alignment mark also can comprise the grating of two groups of above different cycles.
Compared with prior art, the present invention has adopted the amplitude type of two groups or more different cycles with reference to grating and alignment mark, described each branch's grating with reference to grating and described alignment mark is made up of the strip structure of width equal-difference arrangement, can make scanning strength signal peak value more sharp-pointed, improved the reliability of alignment system, only use in the alignment procedures alignment mark ± 1 order diffraction light beam, looking like with corresponding with reference to behind the raster scanning than the minor cycle grating is relevant in the alignment mark, the sweep signal intensity peak that utilization obtains is as slightly catching, utilize in the alignment mark phase information than the relevant picture of large period grating to obtain smart capturing information slightly catching the basis, and in conjunction with being used for fine alignment than the relevant picture of minor cycle grating and the corresponding phase information that obtains with reference to raster scanning in the alignment mark, reduced the aligned position error that the alignment mark asymmetrical deformation causes, reduce the complexity of optical system, improved the efficiency of light energy utilization.
Obviously, those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention. Like this, if these modifications of the present invention and modification belong to the range of claim of the present invention and equivalent technologies thereof, then the present invention also is intended to comprise these change and modification.
Claims (14)
1. alignment system that is used for lithographic equipment comprises:
Aim at radiation source module, be provided for the radiation source of alignment system;
Lighting module transmits the radiation source of described aligning radiation source module, the alignment mark on collimated illumination silicon chip or the datum plate;
The alignment optical module, gather the diffracted beam of alignment mark corresponding stage time and coherent imaging at amplitude type with reference to stop position; And
The acquisition of signal module, it comprises: amplitude type is with reference to grating, detector and signal processing, coherent imaging by the alignment mark diffracted beam and respective amplitudes type are surveyed and are handled through the aligning light intensity signal of amplitude type with reference to Grating Modulation with reference to the scanning of grating;
It is characterized in that described amplitude type comprises the grating of different cycles more than two groups with reference to grating, described amplitude type is a diamond structure with reference to each branch's grating of grating, and it is made up of the strip structure that big gradually little equal difference is arranged from the centre to both sides width;
Described alignment mark comprises the grating of two groups of above different cycles, and each branch's grating of described alignment mark is a diamond structure, and it is made up of the strip structure that big gradually little equal difference is arranged from the centre to both sides width.
2. the alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that, described amplitude type comprises directions X first grating, directions X second grating that is arranged in order along directions X with reference to grating; Y direction first grating, Y direction second grating that are arranged in order along the Y direction;
Described directions X first grating, described directions X second grating, described Y direction first grating, described Y direction second grating are distinguished corresponding with each branch's grating of described alignment mark;
Described amplitude type looks like to scan to corresponding alignment mark grating interference respectively with reference to grating, obtains directions X second sweep signal, directions X first sweep signal, directions X the 3rd sweep signal, Y direction second sweep signal, Y direction first sweep signal and Y direction the 3rd sweep signal.
3. the alignment system that is used for lithographic equipment as claimed in claim 2 is characterized in that, described amplitude type exchanges as required or moves with reference to branch's grating relative position of grating.
4. the alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that, comprises laser cell in the described aligning radiation source module.
5. the alignment system that is used for lithographic equipment as claimed in claim 4 is characterized in that, described laser cell comprises phase-modulator and intensity modulator unit.
6. the alignment system that is used for lithographic equipment as claimed in claim 4 is characterized in that described laser cell comprises laser instrument, and described laser instrument is gas laser, solid state laser, semiconductor laser or fiber laser.
7. the alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that, described alignment optical module comprises alignment optical system and light-dividing device.
8. the alignment system that is used for lithographic equipment as claimed in claim 7 is characterized in that, described light-dividing device utilizes the separately alignment of two kinds of different wave lengths of polarisation of light character.
9. alignment methods of using the described system of claim 1, it is characterized in that: by the less periodic optical grating in the alignment mark is scanned, obtain first sweep signal and the 3rd sweep signal, by in the alignment mark than the large period raster scanning, obtain second sweep signal; Utilize the phase information of the first sweep signal intensity peak information capture, second sweep signal to obtain thick catch position, utilize the phase information of second sweep signal to catch the phase information of the sweep signal of winning the third place, utilize the phase information of the 3rd sweep signal to carry out fine alignment.
10. alignment methods as claimed in claim 9 is characterized in that, specifically comprises the steps:
Aim at radiation source irradiates through the lighting module transmission and to described alignment mark, diffraction takes place, utilize described alignment mark ± 1 order diffraction light beam through alignment optical module coherent imaging, and utilize the corresponding amplitude type of acquisition of signal module to obtain aiming at light intensity signal as carrying out signal intensity scanning with reference to the described alignment mark of grating pair is relevant, directions X first grating that wherein said amplitude type is arranged along directions X with reference to grating and the relevant picture scanning of the corresponding grating with the directions X alignment mark of directions X second grating obtain directions X and aim at light intensity signal, and Y direction first grating that described amplitude type is arranged along the Y direction with reference to grating and Y direction second grating and the corresponding grating of Y direction alignment mark are concerned with and obtain the Y direction and aim at light intensity signal as scanning;
The described aligning light intensity signal that obtains is connected described amplitude type and will aims at light intensity signal with reference to the Transmission Fibers of grating back and be transferred to the photodetector that is connected with Transmission Fibers and survey through accurate;
Utilize described photodetector to survey the intensity and the phase information that obtain described aligning light intensity signal and carry out position sensing and aligning, by the less periodic optical grating in the described alignment mark is scanned, obtain described first sweep signal and described the 3rd sweep signal, by in the described alignment mark than the large period raster scanning, obtain described second sweep signal; Utilize the phase information of described second sweep signal of the described first sweep signal intensity peak information capture to obtain thick catch position, utilize the phase information of described second sweep signal to catch the phase information of described the 3rd sweep signal, utilize the phase information of described the 3rd sweep signal to carry out fine alignment.
11. alignment methods as claimed in claim 10 is characterized in that, described amplitude type is a diamond structure with reference to each branch's grating of grating, and it is made up of the strip structure that big gradually little equal difference is arranged from the centre to both sides width.
12. alignment methods as claimed in claim 10 is characterized in that, each branch's grating of described alignment mark is a diamond structure, and it is made up of the strip structure that big gradually little equal difference is arranged from the centre to both sides width.
13. alignment methods as claimed in claim 10 is characterized in that, described amplitude type comprises directions X first grating, directions X second grating that is arranged in order along directions X with reference to grating; Y direction first grating, Y direction second grating that are arranged in order along the Y direction;
Described directions X first grating, described directions X second grating, described Y direction first grating, described Y direction second grating are distinguished corresponding with each branch's grating of described alignment mark;
Described amplitude type looks like to scan to corresponding alignment mark grating interference respectively with reference to grating, obtains directions X second sweep signal, directions X first sweep signal, directions X the 3rd sweep signal, Y direction second sweep signal, Y direction first sweep signal and Y direction the 3rd sweep signal.
14. alignment methods as claimed in claim 13 is characterized in that, described amplitude type exchanges as required or moves with reference to branch's grating relative position of grating.
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| CN 200910046828 CN101566800B (en) | 2009-02-27 | 2009-02-27 | Aligning system and aligning method for lithography equipment |
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| CN102243442B (en) * | 2010-05-12 | 2014-11-12 | 上海微电子装备有限公司 | Light source amplitude modulation apparatus for silicon wafer pointing |
| WO2012010458A1 (en) | 2010-07-19 | 2012-01-26 | Asml Netherlands B.V. | Method and apparatus for determining an overlay error |
| CN102385263B (en) * | 2010-08-25 | 2014-10-01 | 中芯国际集成电路制造(上海)有限公司 | Method for aligning previous-layer graphs and photomask applicable to method |
| CN103197505B (en) * | 2012-01-10 | 2015-09-30 | 上海微电子装备有限公司 | Add up based on mark cycle level time light intensity value and judge to find method and the alignment system of alignment mark |
| DE102012210309A1 (en) * | 2012-06-19 | 2013-12-19 | Dr. Johannes Heidenhain Gmbh | Position measuring device |
| CN103713477B (en) * | 2012-09-28 | 2015-11-25 | 无锡华润上华半导体有限公司 | The aligning structure of double face photoetching machine and alignment method |
| CN104748686B (en) * | 2015-04-21 | 2017-07-11 | 中国科学院光电技术研究所 | Device and method for positioning to-be-detected piece by utilizing small-hole diffracted waves |
| CN105737879A (en) * | 2016-03-01 | 2016-07-06 | 中国电子科技集团公司第十三研究所 | Micron grade raster calibration sample wafer with step height |
| CN108121178B (en) * | 2016-11-29 | 2019-08-23 | 上海微电子装备（集团）股份有限公司 | A kind of alignment measurement systems and alignment methods |
| WO2019127522A1 (en) * | 2017-12-29 | 2019-07-04 | 深圳市柔宇科技有限公司 | Laser alignment system and laser alignment method |
| CN110728097B (en) * | 2019-10-18 | 2021-06-22 | 南京诚芯集成电路技术研究院有限公司 | Process quality evaluation method and system for inverted trapezoid or T-shaped structure |
| CN111007703B (en) * | 2019-12-18 | 2021-08-24 | 华虹半导体(无锡)有限公司 | Alignment method of photoetching machine |
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| CN101251725A (en) * | 2008-03-31 | 2008-08-27 | 上海微电子装备有限公司 | Aligning system, mark, method for lithographic device and lithographic device thereof |
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Address after: 201203 Zhangjiang High Tech Park, Shanghai, Zhang Dong Road, No. 1525 Co-patentee after: Shanghai Micro And High Precision Mechine Engineering Co., Ltd. Patentee after: Shanghai microelectronics equipment (Group) Limited by Share Ltd Address before: 201203 Zhangjiang High Tech Park, Shanghai, Zhang Dong Road, No. 1525 Co-patentee before: Shanghai Micro And High Precision Mechine Engineering Co., Ltd. Patentee before: Shanghai Micro Electronics Equipment Co., Ltd. |