CN101251725B - Aligning system, mark, method for lithographic device and lithographic device thereof - Google Patents

Aligning system, mark, method for lithographic device and lithographic device thereof Download PDF

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CN101251725B
CN101251725B CN2008100354053A CN200810035405A CN101251725B CN 101251725 B CN101251725 B CN 101251725B CN 2008100354053 A CN2008100354053 A CN 2008100354053A CN 200810035405 A CN200810035405 A CN 200810035405A CN 101251725 B CN101251725 B CN 101251725B
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grating
alignment mark
alignment
light
light signal
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CN101251725A (en
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徐荣伟
韦学志
杜聚有
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Shanghai Micro Electronics Equipment Co Ltd
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Shanghai Micro Electronics Equipment Co Ltd
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Abstract

The present invention discloses an alignment system, an alignment mark and an alignment method for photoetching devices, as well as a photoetching device. By detecting light intensity changes of +-1 grade diffraction light of a first grating, a second grating and a third grating of the alignment mark on an image plane, wherein the +-1 grade diffraction light is modulated via a reference grating after coherent imaging, the center position of the alignment mark is acquired through the phase information of transmitted light signals, wherein the rough position information of the alignment mark is acquired through the alignment signals of the first grating and the second grating of the alignment mark; the exact position information of the alignment mark is acquired through the alignment signals of the third grating of the alignment mark. The alignment system reduces alignment position error caused by the asymmetrical deformation of the alignment mark, effectively solves the problems of signal crosstalk, improves the energy utilization ratio of a light source, and is beneficial to improve the intensity of alignment signals and the dynamic range of detection.

Description

The alignment system and mark, alignment methods and the lithographic equipment that are used for lithographic equipment
Technical field
The present invention is relevant with the lithographic equipment that integrated circuit or other microdevice are made the field, particularly a kind of alignment system, alignment mark, alignment methods and lithographic equipment.
Background technology
Lithographic equipment of the prior art is mainly used in the manufacturing of integrated circuit (IC) or other microdevice.By lithographic equipment, the multilayer mask with different mask patterns is imaged on the wafer that is coated with photoresist under accurately aiming at successively, for example semiconductor wafer or LCD plate.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 wafer, wafer 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 wafer, repeat the picture that this process all exposure areas on wafer all have mask pattern.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 wafer move with respect to optical projection system and projected light beam simultaneously.
Critical step is with mask and wafer aligned in the lithographic equipment.After exposing on wafer, the ground floor mask pattern from device, removes, after the PROCESS FOR TREATMENT that wafer 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 wafer accurately need be aimed at respect to the accurate location of exposed mask pattern image on the wafer.IC device by the photoetching technique manufacturing needs multiexposure, multiple exposure to form multilayer circuit in wafer, for this reason, requires the configuration alignment system in the lithographic equipment, realizes the accurate aligning of mask and wafer.When characteristic dimension requires more hour, the requirement of alignment precision and consequent requirement to alignment precision are become strict more.
The alignment system of lithographic equipment, its major function are to realize mask-wafer aligned before the alignment exposure, promptly measure the coordinate (X of wafer in coordinate system of machine W, Y W, Φ WZ), and the coordinate (X of mask in coordinate system of machine R, Y R, Φ RZ), and calculate the position of mask with respect to wafer, to satisfy 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, the alignment mark of the periodic phase optical grating construction that laser lighting is provided with on wafer, diffraction light or scattered light by the collected wafer alignment marks of the projection objective of lithographic equipment shine on mask alignment mark, and this alignment mark can be amplitude or phase grating.Behind the mask mark detector is set, when scanning wafer under projection objective, surveys the light intensity that sees through the mask mark, the maximal value of detector output is represented correct alignment position.This 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 wafer and the wafer station by the off-axis alignment systematic survey, realizes that wafer aligned and wafer station aim at; The reference mark of datum plate is aimed at mask alignment mark on the wafer station, realizes mask registration; The position relation of mask and wafer be can obtain thus, mask and wafer aligned realized.
At present, the most phase grating technique of alignment that adopts of the alignment system of main flow lithographic equipment.The phase grating technique of alignment is meant that diffraction and reflection take place illumination beam on phase grating type alignment mark, carry the diffraction of the whole of alignment mark or local location information and the center that reflected light obtains alignment mark by detection.Senior diffraction light scatters from the phase alignment grating with wide-angle, after filtering zero order light by spatial filter, gather diffraction light ± 1 order diffraction light, the perhaps raising that requires along with CD, gather multi-level diffraction light (comprising senior time) simultaneously in picture plane interference imaging, through photodetector and signal Processing, determine the centering adjustment position.
A kind of situation of prior art (referring to (1) Chinese invention patent, publication number: CN1506768A, denomination of invention: the alignment system and the method that are used for etching system; (2) Chinese invention patent, publication number: CN1495540A, denomination of invention: alignment system and the method for utilizing the etching system of at least two wavelength), the off-axis alignment system of a kind of 4f system architecture that Holland ASML company is adopted, this 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 relevant of alignment mark multi-level diffraction light; 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.
The aligned position error that this alignment system causes to reduce the alignment mark asymmetrical deformation by the multilevel diffraction light that comprises senior diffraction light of surveying alignment mark.The concrete positive and negative level time hot spot correspondence that adopts voussoir array or wedge group to realize the alignment mark multi-level diffraction light is overlapping, relevant, and the deviation of diffraction light light beams at different levels by voussoir array or the wedge group grating pictures at different levels that make alignment mark be used for the grating X8.0 that the x direction aims at are arranged in picture in image planes along the y direction simultaneously; The grating pictures at different levels that are used for the grating Y8.0 of y direction aligning are arranged in picture in image planes along the x direction, 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 picture scanning at different levels correspondence with reference to grating.But when using the voussoir 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.
Summary of the invention
The object of the present invention is to provide a kind of alignment system, alignment mark, alignment methods and lithographic equipment that is used for lithographic equipment, reduce the aligned position error that the alignment mark asymmetrical deformation causes, solve the cross-interference issue of signal, improve the capacity usage ratio of light source, improved the dynamic range of registration signal intensity and detection.
In order to achieve the above object, the invention provides a kind of alignment system that is used for lithographic equipment, this system comprises at least: light source module is provided for the illuminating bundle of alignment system; Lighting module, the illuminating bundle of transmission light source module, the alignment mark on the illumination wafer; Image-forming module, to the alignment mark imaging, it comprises the object lens and first imaging optical path at least, this module is collected the reflected light and the diffraction light of alignment mark by object lens, and is transferred to this first imaging optical path to this alignment mark imaging; Detecting module, at least comprise with reference to grating and first and survey light path, this detecting module is surveyed light path by first and is surveyed alignment mark after the first imaging optical path imaging of image-forming module and by the transmitted light intensity with reference to Grating Modulation, obtains first light signal, second light signal and the 3rd light signal in the alignment mark scanning process; Signal Processing and locating module are used to handle first light signal, second light signal and the 3rd light signal, and determine the center of alignment mark according to the phase information of first light signal, second light signal and the 3rd light signal.
Include laser cell in this light source module.This laser cell includes phase-modulator.Include laser instrument in this laser cell, this laser instrument can be gas laser, solid state laser, semiconductor laser, perhaps fiber laser.
Comprise the Flattened Gaussian Beams integer type device in this light source module.
This illuminating bundle is for comprising the laser lighting light beam of two discrete wavelength at least.This laser lighting light beam that comprises two discrete wavelength at least can adopt four discrete wavelength, and wherein has two wavelength at least near infrared or infrared band.
This polarization state that shines the illuminating bundle on the wafer is a circularly polarized light.
This shines the oblong hot spot that the illuminating bundle on the wafer extends perpendicular to the direction of aligning direction for the edge.This oblong illumination hot spot is not simultaneously but along with the different moving directions of wafer station alternately produce, on wafer, form the oblong illumination hot spot that extends along the y direction in the x direction to punctual, on wafer, form the oblong illumination hot spot that extends along the x direction to punctual in the y direction.This oblong illumination hot spot can be by fast gate control, and the two-way illumination path that alternate selection comprises different reshapers produces.This oblong illumination hot spot also can be alternately driven by using two, and the LASER Light Source with difform shutter realizes; Also can use single LASER Light Source to realize with variable shutter.This oblong illumination hot spot can also realize that this variable illumination diaphragm comprises programmable liquid crystal light valve by the variable illumination diaphragm of shape variable.
This alignment mark is the marking groove alignment mark, at least the grating that comprises three groups of different cycles: first grating, second grating and the 3rd grating, this first grating, second grating and the 3rd grating are arranged along the direction perpendicular to aligning direction, and the alignment mark that is used for x direction aligning is positioned at the marking groove of y direction, and the alignment mark that is used for y direction aligning is positioned at the marking groove of x direction.This alignment mark can further include the 4th grating that the cycle is different from this first grating, second grating and the 3rd grating, the perhaps grating more than four.This first imaging optical path make first grating, second grating and the 3rd grating of forming alignment mark ± 1 order diffraction light respectively coherent imaging be positioned on the reference grating of image planes.This comprises three groups of amplitude gratings with reference to grating, corresponds respectively to 1 grade of grating picture of this first grating, second grating and the 3rd grating; The arrangement mode of these three groups of amplitude gratings is identical with alignment mark, arranges along the direction perpendicular to aligning direction; These three groups of amplitude gratings can equal the length of corresponding 1 grade of grating picture along the length of cycle direction, also can be greater than the length of 1 grade of grating picture of correspondence.This can also comprise five groups of amplitude gratings with reference to grating, comprises one group of two-dimensional grating and is distributed in two-dimensional grating four groups of one-dimensional gratings on every side, and wherein four groups of one-dimensional gratings correspond respectively to first grating of alignment mark and 1 grade of grating picture of second grating; Two-dimensional grating is corresponding to 1 grade of grating picture of the 3rd grating; Five groups of gratings can equal the length of corresponding 1 grade of grating picture along the length of cycle direction, also can be greater than the length of 1 grade of grating picture of correspondence.This two-dimensional grating is made up of some diamond structures that are arranged in rows and columns, can be as the reference grating of x and y both direction aligning.The arrangement mode that is used for three groups of gratings that same direction aims in these five groups of amplitude gratings is identical with alignment mark, along the direction arrangement perpendicular to aligning direction.
This first detection light path is connected with first imaging optical path, and the picture of surveying first grating, second grating and the 3rd grating of forming alignment mark obtains first light signal, second light signal and the 3rd light signal through with reference to the variation of the transmitted light intensity after the Grating Modulation.
This signal Processing and locating module are handled first light signal and second light signal, obtain the rough center of alignment mark according to the phase information of first light signal and second light signal; Handle the 3rd light signal,, and obtain the accurate center of alignment mark in conjunction with the rough center of alignment mark according to the phase information of the 3rd light signal.
This first imaging optical path can also comprise a beam splitter, makes the diffraction light of a direction of alignment mark reflect fully, and the diffraction light of another perpendicular direction sees through fully.
This bi-directional beam divider comprises reflector space and regional transmission, and this reflector space reflects incident light fully, and this regional transmission sees through incident light fully; The distribution of this reflector space and regional transmission can be that zone line is a regional transmission, and two side areas is a reflector space, also can be that zone line is a reflector space, and two side areas is a regional transmission.
This image-forming module also comprises second imaging optical path, and the division line on first grating of alignment mark and the graticule is imaged on the CCD camera together.
This detecting module also comprises second and surveys light path, is connected with second imaging optical path, and direct detection alignment mark picture, the video that is used for the alignment mark position is monitored and manual alignment; Also can be used for Flame Image Process and pattern-recognition.
This image-forming module also comprises the polychromatic light piece-rate system, realizes the separation of the alignment mark diffraction light of multi-wavelength.This polychromatic light piece-rate system is based on dispersion element, perhaps dichroism element, the perhaps beam splitting system of diffraction optical element.
The present invention also provides a kind of alignment mark that is used for this alignment system, this alignment mark comprises the grating of three groups of different cycles at least: first grating, second grating and the 3rd grating, this first grating, second grating and the 3rd grating are arranged along the direction perpendicular to aligning direction.The center of first grating of this alignment mark, second grating and the 3rd grating overlaps, and whole alignment mark is the symcenter structural symmetry with this center.The position of first grating of this alignment mark, second grating and the 3rd grating can be changed arbitrarily, and promptly the position of any one group of grating can be centre or the edge that is positioned at whole mark in three groups of gratings.This alignment mark is the marking groove alignment mark, and is used for the marking groove that alignment mark that the x direction aims at is positioned at the y direction, is used for the marking groove that alignment mark that the y direction aims at is positioned at the x direction.This alignment mark can further include the 4th grating that the cycle is different from first grating, second grating and the 3rd grating, perhaps four above gratings.
The present invention also provides a kind of alignment methods of using this alignment system to carry out wafer aligned, may further comprise the steps:
Laser lighting light beam through lighting module transmission light source module is sent forms the oblong hot spot on wafer, and the irradiation alignment mark;
Object lens by image-forming module are gathered the reflected light and the diffraction light of alignment mark, and first imaging optical path in image-forming module is to the alignment mark imaging;
Survey light path by first in the detecting module and survey alignment mark after the first imaging optical path imaging and, in the alignment mark scanning process, obtain first light signal, second light signal and the 3rd light signal by transmitted light intensity with reference to Grating Modulation;
Handle this first light signal, second light signal and the 3rd light signal through signal Processing and locating module, and determine the center of alignment mark according to the phase information of this first light signal, second light signal and the 3rd light signal.
The present invention also provides a kind of lithographic equipment that comprises this alignment system, and its formation comprises:
Illuminator is used to transmit exposing light beam; Mask platform is used to support the mask holder of mask, the alignment mark that mask pattern is arranged on the mask and have periodic structure; Projection optical system is used for the mask pattern on the mask is projected to wafer; Chip support and wafer station are used for supporting wafer, and the datum plate that contains reference mark is arranged on the wafer station, have the alignment mark of periodicity optical structure on the wafer; Alignment system is used for wafer aligned and wafer station and aims at, and it is arranged between this mask platform and this wafer station; The coaxial alignment module is used for mask registration; Catoptron and laser interferometer are used for mask platform and wafer station position measurement; And by the mask platform of master control system control and the servo-drive system and the drive system of wafer station displacement drive.
Wherein, this alignment system comprises at least: light source module is provided for the illuminating bundle of alignment system; Lighting module, the illuminating bundle of transmission light source module, the alignment mark on the illumination wafer; Image-forming module, to the alignment mark imaging, it comprises object lens and first imaging optical path at least, this module is collected the reflected light and the diffraction light of alignment mark by object lens, and is transferred to this first imaging optical path to this alignment mark imaging; Detecting module, at least comprise with reference to grating and first and survey light path, this detecting module is surveyed light path by first and is surveyed alignment mark after the first imaging optical path imaging of image-forming module and by the transmitted light intensity with reference to Grating Modulation, obtains first light signal, second light signal and the 3rd light signal in the alignment mark scanning process; Signal Processing and locating module are used to handle first light signal, second light signal and the 3rd light signal, and determine the center of alignment mark according to the phase information of first light signal, second light signal and the 3rd light signal.This alignment mark is marking groove (Scribe Lane) alignment mark, at least the grating that comprises three groups of different cycles: first grating, second grating and the 3rd grating, this first grating, second grating and the 3rd grating are arranged along the direction perpendicular to aligning direction, and the alignment mark that is used for x direction aligning is positioned at the marking groove of y direction, and the alignment mark that is used for y direction aligning is positioned at the marking groove of x direction.This shines the oblong hot spot that the illuminating bundle on the wafer extends perpendicular to the direction of aligning direction for the edge.
The present invention has adopted the alignment mark of the grating that comprises at least three group different cycles, and the centering adjustment position of three groups of gratings overlaps, and the minor cycle grating is used for fine alignment, has reduced the aligned position error that the alignment mark asymmetrical deformation causes.Simultaneously, forming three groups of gratings of alignment mark arranges along the direction perpendicular to aligning direction, and the alignment mark that is used for x direction aligning is positioned at the marking groove of y direction, the alignment mark that is used for y direction aligning is positioned at the marking groove of x direction, avoided in the alignment scanning, the grating picture of different cycles scanned a situation with reference to grating, the cross-interference issue of effective address signal simultaneously when alignment mark was respectively organized grating picture scanning correspondence with reference to grating.Simultaneously, shine the oblong hot spot that the illuminating bundle on the wafer extends perpendicular to the direction of aligning direction for the edge, improved the capacity usage ratio of light source, help improving the dynamic range of registration signal intensity and detection.
Description of drawings
Fig. 1 is the alignment system of lithographic equipment of the present invention and the total arrangement between the lithographic equipment, principle of work structural representation;
Fig. 2 (a) and Fig. 2 (b) are the synoptic diagram of wafer alignment marks among Fig. 1;
Fig. 3 is the system architecture synoptic diagram of alignment system first embodiment of the present invention;
Fig. 4 is the beam-splitting surface synoptic diagram of bi-directional beam divider of the present invention;
Fig. 5 is the synoptic diagram of the illumination hot spot scanning wafer alignment marks of alignment system first embodiment of the present invention;
Fig. 6 (a) and Fig. 6 (b) are the reference grating synoptic diagram of alignment system first embodiment of the present invention;
Fig. 7 is the registration signal synoptic diagram of alignment system first embodiment of the present invention;
Fig. 8 is the system architecture synoptic diagram of alignment system second embodiment of the present invention;
Fig. 9 is the reference grating synoptic diagram of alignment system second embodiment of the present invention;
Figure 10 is the alignment mark of technology formerly and with reference to the grating structural representation;
In the accompanying drawing: 1, illuminator; 2, mask; 3, mask platform; 4, projection optical system; 5, from the shaft type alignment system; 6, wafer; 7, wafer station; 8, datum plate; 9, drive system; 10, catoptron; 11, laser interferometer; 12, master control system; 13, servo-drive system; 14 drive systems; 15, laser interferometer; 16, catoptron; 500, alignment mark; The alignment mark that 500Y, y direction are aimed at; 5001, first grating; 5002, second grating; 5003, the 3rd grating; 5004, amplify the display part; The alignment mark that 500X, x direction are aimed at; 5005, first grating; 5006, the 3rd grating; 5007, second grating; 5008, amplify the display part; 501, single-mode polarization maintaining fiber; 502, fiber coupler; 503, bundling device; 504, single-mode polarization maintaining fiber; 505, the polarizer; 506, lens; 507, illuminating aperture diaphragm; 508, lens; 509, flat board; 509a, reflecting prism; 510, achromatic λ/4 wave plates; 511, object lens; 512, beam splitter; 512a, beam-splitting surface; 513, spatial filter; 514, polychromatic light piece-rate system; 515, lens combination; 516, with reference to grating; 517, Transmission Fibers bundle; 518, photodetector array; 520, spatial filter; 521, graticule; 522, lens combination; 523, Transmission Fibers; 524, CCD camera; 530, bi-directional beam divider; 530a, beam-splitting surface; 531, polychromatic light piece-rate system; 532, lens combination; 533, with reference to grating; 534, Transmission Fibers; 535, photodetector; 536, polychromatic light piece-rate system; 537, lens combination; 538, Transmission Fibers; 539, Transmission Fibers; 540, photodetector; 550, grating; 551, grating; 552, grating; 553, grating; 554, grating; 555, optical fiber; 556, optical fiber; 557, optical fiber; 558, optical fiber; 559, optical fiber; 560, grating; 561, grating; 562, grating; 563, Transmission Fibers; 564, Transmission Fibers; 565, Transmission Fibers; 566, grating; 567, grating; 568, grating; 569, Transmission Fibers; 570, Transmission Fibers; 571, Transmission Fibers; 580, illumination hot spot; 581, illumination hot spot; P 1, first light signal; P 2, second light signal; P 3, the 3rd light signal; FM, reference mark; RM, mask alignment mark; EF, exposure field.
Embodiment
Below in conjunction with accompanying drawing the specific embodiment of the present invention is further described.
Figure 10 shows the alignment mark of technology formerly and with reference to the grating structural representation, adopt voussoir array or wedge group to realize that the positive and negative level time hot spot correspondence of alignment mark multi-level diffraction light is overlapping, relevant, the deviation of diffraction light light beams at different levels by voussoir array or the wedge group grating pictures at different levels that make alignment mark be used for the grating X8.0 that the x direction aims at are arranged in picture in image planes along the y direction simultaneously; The grating pictures at different levels that are used for the grating Y8.0 of y direction aligning are arranged in picture in image planes along the x direction, 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 picture scanning at different levels correspondence with reference to grating.But when using the voussoir 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.
Fig. 1 shows the alignment system of lithographic equipment of the present invention and the total arrangement between the lithographic equipment, principle of work structural representation.The formation of 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 mask 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 wafer 6; Be used for the chip support and the wafer station 7 of supporting wafer 6, the datum plate 8 that is carved with reference mark FM is arranged on the wafer station 7, the alignment mark 500 of periodicity optical structure is arranged on the wafer 6; Be used for mask and wafer aligned from shaft type alignment system 5; The catoptron 10,16 and the laser interferometer 11,15 that are used for mask platform 3 and wafer station 7 position measurements, 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 wafer station 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), F 2Laser instrument (wavelength 157nm), Kr 2Laser instrument (wavelength 146nm), Ar 2Laser 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 mask alignment 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 refraction type or refractive and reflective optical system 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 wafer 6 that is coated with photoresist through projection optical system.
Wafer station 7 is positioned at the below of projection optical system 4, and wafer station 7 is provided with a chip support (not shown), and wafer 6 is fixed on the support.Wafer station 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 wafer 6 to be positioned in the exposure light field, and carry out the step-scan operation.The position of wafer station 7 in X-Y plane recorded by Doppler's two-frequency laser interferometer 11 precisions by a catoptron 10 that is positioned on the wafer station, the positional information of wafer station 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 wafer platforms 7.
Wafer 6 is provided with the alignment mark 500 of periodic structure, and the datum plate 8 that comprises reference mark FM is arranged on the wafer station 7, and alignment system 5 realizes that by wafer alignment marks 500 and reference mark FM wafer 6 is aimed at and wafer station 7 is aimed at respectively.In addition, coaxial alignment module (not shown) is aimed at the reference mark FM of datum plate on the wafer station 8 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 module, and after data processing, drive system 9 drives wafer station 7 and moves the aligning of realizing mask and wafer 6.
Fig. 2 is the structural representation of wafer alignment marks 500 among Fig. 1.Alignment mark 500 is marking groove (Scribe Lane) alignment marks, is that dutycycle is 1: 1 a phase grating structure, and wherein Fig. 2 (a) is used for the alignment mark 500Y that the y direction is aimed at.Referring to Fig. 5, alignment mark 500Y is arranged in the marking groove of x direction.Alignment mark 500Y comprises the grating of three groups of different cycles: first grating 5001, second grating 5002 and the 3rd grating 5003, wherein the grating cycle of first grating 5001 is P 1, the grating cycle of second grating 5002 is P 2, the grating cycle of the 3rd grating 5003 is P 3Three groups of gratings of alignment mark 500Y: first grating 5001, second grating 5002 and the 3rd grating 5003 are arranged along the direction perpendicular to aligning direction, and three groups of gratings that promptly are used for the alignment mark 500Y of y direction aligning are arranged along the x direction.In addition, the position between three groups of gratings can be changed arbitrarily, and promptly the position of any one group of grating can be centre or the edge that is positioned at whole mark in three groups of gratings.
As amplifying among the figure shown in the display part 5004, the centering adjustment position of three groups of gratings of alignment mark 500Y overlaps, and whole alignment mark 500Y is the symcenter structural symmetry with this centering adjustment position.To being used for two groups of gratings that same direction is aimed at: first grating 5001 and second grating 5002, select the different grating cycles can improve the capture range of alignment mark, capture range is expressed as P 1P 2/ [2 (P 1-P 2)].Grating cycle P 1, P 2Be more or less the same, generally get P 2=(1 ± r%) P 1, r=5 or 10 wherein.For example, 5001 cycles of first grating are 14.4um, and 5002 cycles of second grating are 16um, and then capture range is 72um.The cycle P of the 3rd grating 5003 3＜P 1, and P 3＜P 2, be used for fine alignment.For example, the cycle of the 3rd grating 5003 can be 1 μ m.
Equally, shown in Fig. 2 (b), the alignment mark 500X that is used for x direction aligning comprises first grating 5005, second grating 5007 and the 3rd grating 5006, three groups of grating cycles are identical with three groups of grating cycles of alignment mark 500Y, and the centering adjustment position of three groups of gratings overlaps (referring among the figure shown in 5008).Three groups of gratings of alignment mark 500X are along the direction perpendicular to aligning direction, and promptly the y direction is arranged.Referring to Fig. 5, alignment mark 500X is arranged in the marking groove (Scribe Lane) of y direction.
In addition, alignment mark 500 of the present invention can further include the 4th grating that the cycle is different from above-mentioned three groups of gratings, perhaps four above gratings.
Fig. 3 is alignment system 5 structural representations of first embodiment of the invention, and this alignment system 5 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) of a plurality of discrete wavelength that near infrared or infrared band are provided.Lighting module comprises Transmission Fibers and lamp optical system.Image-forming module mainly comprises: the object lens of large-numerical aperture (511), beam splitter 512, bi-directional beam divider 530, spatial filter (513,520), polychromatic light piece-rate system (531,536) and lens combination (522,532,537), graticule 521.Detecting module comprises with reference to grating (533,538), Transmission Fibers (523,534,539), CCD camera 524 and photodetector (535,540).Signal Processing and locating module mainly comprise photosignal conversion and amplification, analog to digital conversion and digital signal processing circuit etc.
The principal character of this alignment system is, first grating, second grating and the 3rd grating by surveying alignment mark in image planes ± 1 order diffraction light coherent imaging is after change with reference to the light intensity of Grating Modulation, obtained the center of alignment mark by the phase information of optical signal transmissive.Wherein obtain the coarse position information of alignment mark, obtain the precise position information of alignment mark by the registration signal of the 3rd grating of alignment mark by the registration signal of first grating of alignment mark and second grating.
This alignment system can produce the registration signal with strong Technological adaptability, high sensitivity and high s/n ratio, and the alignment system repeatability precision can reach 3-5nm, satisfy fully live width 90nm and 90nm following to alignment request.
Referring to Fig. 3, the light source module of alignment system 5 provides the illuminating bundle that comprises a plurality of discrete wavelength, comprises the illuminating bundle of two discrete wavelength at least, for example, and 633nm and 785nm; Four discrete wavelength of preferential employing, and wherein have two wavelength at least near infrared or infrared band.For example, 532nm, 633nm, 785nm and 850nm.Multi-wavelength (λ 1, λ 2, λ 3And λ 4) illuminating bundle is through single-mode polarization maintaining fiber 501 transmission, is coupled into bundling device 503 through fiber coupler 502 then, outputs to the lighting module of alignment system 5 again by single-mode polarization maintaining fiber 504.
The preferential high-brightness laser light source that uses, in light source module, include the laser cell (not shown), for improving signal to noise ratio (S/N ratio), in laser cell, adopt phase-modulator that laser beam is carried out phase modulation (PM), and the registration signal that detects is carried out demodulation in signal Processing and locating module.Employed LASER Light Source can be gas laser, solid state laser, semiconductor laser, perhaps fiber laser etc.In addition, also comprise Flattened Gaussian Beams (Flat-top Gaussian beam) shaper (not shown) in the light source module, be used for the Gaussian beam integer is become Flattened Gaussian Beams.
Above-mentioned alignment system uses the multiwavelength laser illuminating bundle, can suppress the influence of the destructive interference effect of many process layers generations, improves Technological adaptability; Use the light illumination of near infrared and far infrared wavelength, can effectively solve the absorption problem of the dielectric material of low k value in limit of visible spectrum, and can be used for the marker detection of polysilicon process layer, and the alignment requirements in the compatible dual masks technology simultaneously, thus registration signal intensity improved.
As shown in Figure 3, lighting module comprises Transmission Fibers 504 and lamp optical system, the multi-wavelength illuminating bundle passes through the polarizer 505, lens 506, illuminating aperture diaphragm 507 and lens 508 successively, and the reflecting prism 509a on dull and stereotyped 509 impinges perpendicularly on achromatic λ/4 wave plates 510 then.
Less when the alignment mark grating cycle, during with illumination wavelengths magnitude suitable (referring generally to) less than 5 λ, diffraction efficiency of grating is relevant with the polarization characteristic of illuminating bundle, therefore utilize achromatic λ/4 wave plates 510, make linearly polarized light behind achromatic λ/4 wave plates 510, the illumination hot spot that incides on the wafer through object lens 511 is a circularly polarized light, and circularly polarized light comprises the vertical linearly polarized light of both direction, guarantees always to have a polarization direction can produce high efficiency diffraction light.
The multi-wavelength illuminating bundle impinges perpendicularly on the wafer alignment marks through object lens 511, and reflection or diffraction take place.Object lens 511 are to aim at key element in the imaging optical path, and these lens must have the multilevel diffraction light of enough big numerical aperture (for example NA=0.8) with on the wafer alignment mark different color light of collecting.When NA=0.8, if use the lighting source of wavelength 850nm, then can survey pitch is the less grating alignment marks of 1.1 μ m.In addition, for guaranteeing between wafer and alignment system suitable distance is arranged, the object lens of preferred long working distance.
The multi-wavelength illuminating bundle is an oblong through the illumination optical system object lens 511 formed illumination hot spot on wafer of unifying, shown in the hot spot among Fig. 5 580 and 581.Oblong illumination hot spot 580 and 581 is not simultaneously but along with the different moving directions of wafer station alternately produce, on wafer, form the oblong illumination hot spot 581 that extends along the y direction in the x direction to punctual, on wafer, form the oblong illumination hot spot 580 that extends along the x direction to punctual in the y direction.A kind of method is the two-way light path (not showing among Fig. 3) that illumination path is designed to respectively have a fast gate control, the reshaper (as refracting prisms) of the leading up to hot spot that will throw light on is shaped to oblong hot spot 580, another road is shaped to oblong hot spot 581 by another vertical reshaper (as refracting prisms) of placing hot spot that will throw light on, alternately produces the orthogonal oblong hot spot 580 and 581 that throws light on by two fast gate controls on wafer.Another method, can be alternately driven by using two, and the LASER Light Source with difform shutter realizes that the shutter of one of them LASER Light Source has the slit (as the x direction) of a direction, is used for producing oblong illumination hot spot 580; The shutter of another LASER Light Source has the slit (as the y direction) of another vertical direction, is used for producing oblong illumination hot spot 581.In addition, can also use single LASER Light Source to realize with variable shutter, or the variable illumination diaphragm of shape variable (for example, programmable liquid crystal light valve) realizes, one of them shutter or diaphragm have the slit (as the x direction) of a direction, the slit (as the y direction) that the shutter of another LASER Light Source or illumination diaphragm have another vertical direction.Also comprise other similar implementation methods in addition.
Fig. 5 has provided alignment mark structure shown in Figure 2 laying situation in the wafer scribe groove.Being marking groove between the exposure field EF on the wafer, in orthogonal marking groove, be laid with alignment mark 500X and 500Y, alignment mark 500X is used for the aligning of x direction, be arranged in y to marking groove; Alignment mark 500Y is used for the aligning of Y direction, be arranged in x to marking groove.Alignment mark 500Y and 500X are positioned at the zone line of marking groove, and for preventing the signal cross-talk from the IC product structure, the raster width of alignment mark 500Y and 500X for example is 72 μ m or 36 μ m less than the marking groove width.Carrying out the y direction on time, along with the displacement of wafer station 7 along the y direction, oblong illumination hot spot 580 is along y scanning direction alignment mark 500Y; Carrying out the x direction on time, along with the displacement of wafer station 7 along the x direction, oblong illumination hot spot 581 is along x scanning direction alignment mark 500X.
Image-forming module comprises first imaging optical path (be automatic optical system for alignment, comprise coarse alignment and fine alignment) and second imaging optical path (being the CCD imaging optical path).Wherein, second imaging optical path is imaged on the division line on alignment mark and the graticule on the CCD camera photosurface together, is used for the monitoring of manual alignment and video on the one hand, also can carry out Flame Image Process and pattern-recognition on the other hand.Second imaging optical path comprises object lens 511, achromatic λ/4 wave plates 510, beam splitter 512, spatial filter 520, graticule 521, lens combination 522 etc.
First imaging optical path make alignment mark first grating, second grating and the 3rd grating ± 1 order diffraction light respectively coherent imaging on three groups of gratings of the reference grating correspondence that is positioned at image planes.First imaging optical path comprises object lens 511, achromatic λ/4 wave plates 510, beam splitter 512, spatial filter 513, bi-directional beam divider 530, polychromatic light piece- rate system 531 and 536, lens combination 532 and 537.
Detecting module comprises that first surveys the light path (comprising coarse alignment and fine alignment detection light path) and the second detection light path (being CCD imaging detection light path), is connected with second imaging optical path with first imaging optical path respectively.First surveys the transmitted light intensity variation of grating picture after correspondence is with reference to Grating Modulation that light path is surveyed first grating, second grating and the 3rd grating, obtain first light signal, second light signal (is the coarse alignment signal, be used for coarse alignment or catch alignment mark) and the 3rd light signal (be the fine alignment signal, be used for fine alignment).First surveys light path comprises with reference to grating 533 and 538, Transmission Fibers 534 and 539, photodetector 535 and 540.Second surveys light path comprises Transmission Fibers 523 and CCD camera 524.
Reflection and diffraction take place in multi-wavelength illuminating bundle illumination wafer alignment marks 500, produce a series of diffraction patterns on the frequency plane of object lens 511, respectively the grating part of alignment mark 500 different cycles.The diffraction light of alignment mark 500 enters beam splitter 512 behind object lens 511 collimations, 512a is divided into two-way through beam-splitting surface, and one the tunnel enters second imaging optical path, and another road enters first imaging optical path.
Second imaging optical path, be in the CCD imaging optical path, come from first grating 5001 of alignment mark and 5005 multi-wavelength ± a part of light beam of 1 order diffraction light is through spatial filter 520 and a graticule 521 that is carved with division line, through lens 522 and Transmission Fibers 523 first grating 5001,5005 and division line are imaged on the CCD camera 524 together then, be used for the monitoring of manual alignment and video on the one hand, also can carry out Flame Image Process and pattern-recognition on the other hand, be used for auxiliary aligning automatically.In addition, the CCD imaging optical path also can be positioned at monochromatic light path (as λ 1Light path) in, this moment, imaging was a filtergram.
The multi-wavelength diffraction light that enters first imaging optical path is at first through a spatial filter 513, feasible first grating 5001 that has only alignment mark 500Y, 5003 of second grating 5002 and the 3rd grating, and first grating 5005 of alignment mark 500X, second grating 5007 and the 3rd grating 5006 ± 1 order diffraction light can pass through, zero order light, other level time diffraction light and parasitic light are filtered, and eliminate the parasitic light cross talk effects of being close to mark or product structure on the wafer simultaneously.The multi-wavelength that sees through ± 1 order diffraction light makes the diffraction light of different directions separate through the beam-splitting surface 530a of bi-directional beam divider 530.The diffraction light of one of them direction (for example y direction diffraction light of alignment mark 500Y generation) sees through bi-directional beam divider 530, and the diffraction light of another direction (for example x direction diffraction light of alignment mark 500X generation) is through the beam-splitting surface 530a of bi-directional beam divider 530 reflection.The structure of beam-splitting surface 530a as shown in Figure 4, comprise two regional a and b, it is regional transmission that zone a is positioned at the beam-splitting surface centre position, make the diffraction light of a certain direction (for example y direction) can directly see through bi-directional beam divider 530, it is reflector space that zone b is positioned at beam-splitting surface two side positions, makes the diffraction light of other direction (for example x direction) reflect fully.Can realize above-mentioned functions by beam-splitting surface 530a is carried out the regional area plated film, for example to regional b plating reflectance coating, regional a plating anti-reflection film; Also can directly the beam splitter material of regional transmission correspondence be removed to form through hole, for example on beam splitter, the pairing part of regional a be made through hole, allow light beam directly pass.Equally, also can make regional a is reflector space, and regional b is a regional transmission.Further, beam-splitting surface 530a can also comprise more reflection and regional transmission.
See through bi-directional beam divider 530 alignment mark 500Y multi-wavelength ± 1 order diffraction light is at first through a polychromatic light piece-rate system 536, makes the diffraction light of different colours separate, and only provided wherein a kind of wavelength X among Fig. 3 1Light path, wavelength is λ 1Alignment mark 500Y ± 1 order diffraction light is through the grating of lens 537, three groups of different cycles: first grating, 5001, the second gratings, 5002, the three gratings 5003 ± the corresponding coherent imaging of 1 order diffraction light is being positioned on the reference grating 538 of image planes.Referring to Fig. 6 (a), comprise three groups of amplitude gratings with reference to grating 538: grating 560, grating 561 and grating 562 correspond respectively to 1 grade of grating picture of 5003 and second grating 5002 of first grating 5001, the 3rd grating of alignment mark 500Y.The arrangement mode of three groups of amplitude gratings is similar to alignment mark 500Y, and along the direction perpendicular to aligning direction (y direction), promptly the x direction is arranged.Three groups of amplitude gratings can equal the length of corresponding 1 grade of grating picture along the length of cycle direction, and at this moment the registration signal of Chan Shenging has a leg-of-mutton envelope; Perhaps three groups of amplitude gratings also can be greater than the length of 1 grade of grating picture of correspondence along the length of cycle direction, and the registration signal approximate trapezoid of Chan Shenging at this moment has the envelope of one section flat-top.Be respectively arranged with Transmission Fibers 563,564 and 565 behind three groups of amplitude gratings, to be transferred to corresponding photo detector 540 with reference to the transmitted light of grating 538, in alignment mark 500Y scanning process, obtain the registration signal of the y direction of alignment mark 500Y, as shown in Figure 7, comprise the first light signal P 1, the second light signal P 2With the 3rd light signal P 3
Another part through the multi-wavelength of the alignment mark 500X of bi-directional beam divider 530 reflection ± 1 order diffraction light is at first through a polychromatic light piece-rate system 531, makes the diffraction light of different colours separate, and only provided wherein a kind of wavelength X among Fig. 3 1Light path, wavelength is λ 1Alignment mark 500X ± 1 order diffraction light is through the grating of lens 532, three groups of different cycles: first grating, 5005, the second gratings 5007 and the 3rd grating 5006 ± the corresponding coherent imaging of 1 order diffraction light is being positioned on the reference grating 533 of image planes.Referring to Fig. 6 (b), comprise three groups of amplitude gratings with reference to grating 533: grating 566, grating 568 and grating 567 correspond respectively to 1 grade of grating picture of 5006 and second grating 5007 of first grating 5005, the 3rd grating.The arrangement mode of three groups of amplitude gratings is similar to alignment mark 500X, and along the direction perpendicular to aligning direction (x direction), promptly the y direction is arranged.Equally, three groups of amplitude gratings can equal or also can be greater than the length of 1 grade of grating picture of correspondence along the length of cycle direction.Be respectively arranged with Transmission Fibers 569,570 and 571 behind three groups of amplitude gratings, to be transferred to corresponding photo detector 535 with reference to the transmitted light of grating 533, in alignment mark 500X scanning process, obtain the registration signal of the x direction of alignment mark 500X, referring to shown in Figure 7, comprise the first light signal P 1, the second light signal P 2With the 3rd light signal P 3
In the wafer station scanning process, first imaging optical path to first grating, second grating and the 3rd grating of alignment mark 500X (or 500Y) ± 1 order diffraction light coherent imaging, first surveys light path surveys the light intensity variation of three grating pictures after the amplitude grating modulation of reference grating correspondence in image planes, obtains the first light signal P respectively 1, the second light signal P 2With the 3rd light signal P 3By the first light signal P 1With the second light signal P 2Phase information obtain the rough center of alignment mark 500X (or 500Y), realize slightly catching of alignment mark 500X (or 500Y); By the 3rd light signal P 3Phase information, and, can obtain the accurate center of alignment mark 500X (or 500Y) in conjunction with the rough center information of alignment mark 500X (or 500Y).Second imaging optical path adopts the CCD camera to survey first grating of alignment mark 500X (or 500Y) and the picture of division line, is used for the monitoring of manual alignment and video on the one hand, also can carry out Flame Image Process and pattern-recognition on the other hand, is used for assisting automatically and aims at.
Fig. 8 is the system architecture synoptic diagram of alignment system second embodiment of the present invention, the structural similarity of this alignment system and first embodiment, difference are the same light path coherent imaging of diffraction light process from the mutually perpendicular direction of alignment mark 500X and alignment mark 500Y.The multi-wavelength of alignment mark 500X (or 500Y) ± 1 order diffraction light again through a polychromatic light piece-rate system 514, makes the diffraction light of different colours separate behind spatial filter 513, only provided wherein a kind of wavelength X among Fig. 8 1Light path, first grating 5005 of alignment mark 500X, second grating 5007 and the 3rd grating 5006 (perhaps first grating, 5001, the second gratings 5002 and the 3rd grating 5003 of alignment mark 500Y) ± 1 order diffraction light through lens combination 515 respectively coherent imaging be positioned on the reference grating 516 of image planes.
As shown in Figure 9, comprise five groups of amplitude gratings with reference to grating 516: grating 550, grating 551, grating 552, grating 553 and grating 554 correspond respectively to first grating 5001 of alignment mark 500Y, 5003 (the 3rd gratings 5006 of alignment mark 500X) and second grating 5002, first grating 5005 of alignment mark 500X and 1 grade of grating picture of second grating 5007 of the 3rd grating.Grating 550, grating 552, grating 553 and grating 554 are one-dimensional grating; Grating 551 is a two-dimensional grating, is made up of some diamond structures that are arranged in rows and columns, and can be used as the reference grating (because alignment mark 500 is one dimension marks, so once can only obtain the registration signal of a direction) of X, Y both direction aligning simultaneously.Three groups of amplitude gratings with reference to grating 516: the arrangement mode of grating 550, grating 551, grating 552 is similar to alignment mark 500Y, and along the direction perpendicular to aligning direction (y direction), promptly the x direction is arranged; Three groups of amplitude gratings: the arrangement mode of grating 553, grating 551, grating 554 is similar to alignment mark 500X, and along the direction perpendicular to aligning direction (x direction), promptly the y direction is arranged.Equally, five groups of amplitude gratings can equal or also can be greater than the length of 1 grade of grating picture of correspondence along the length of cycle direction.Be respectively arranged with Transmission Fibers bundle 517 behind five groups of amplitude gratings, comprise optical fiber 555,556,557,558 and 559, to be transferred to corresponding photo detector array 518 with reference to the transmitted light of respectively organizing grating of grating 516, in alignment mark 500X and 500Y scanning process, obtain the registration signal of alignment mark x and y direction, as shown in Figure 7, comprise the first light signal P 1, the second light signal P 2With the 3rd light signal P 3
Alignment system of the present invention adopts the phase detection technology, when the illuminating bundle of use multi-wavelength throws light on alignment mark simultaneously, the diffraction light of different wave length is overlapped, therefore the necessary separate detection of the registration signal of different wave length needs to use the polychromatic light piece-rate system to separate wavelength optical signals.
Among the present invention, polychromatic light piece-rate system 514,531 and 536 can adopt different principles and device to realize, can comprise for the beam splitting system based on dispersion element: prism (Cornu prism, Li Telu prism etc.), blazed grating and echelon grating; Also can be based on the beam splitting system of dichroism element, interference filter for example also can be based on the beam splitting system of DOE diffraction optical element (for example CSG-chromatic separated grating).
The preferential many blazed gratings of a kind of transmission-type that adopt are as the polychromatic light piece-rate system, the many blazed gratings of described transmission-type comprise broken line type blazed grating and subregion type blazed grating, and many blazed gratings are made up in broken line type-subregion, its concrete form or structure are referring to Chinese invention patent (1) " the level coupling system of a kind of alignment system of lithographic equipment and this alignment system ", publication number: CN1949087; (2) " be used for lithographic equipment alignment system and the level in conjunction with optical-mechanical system ", publication number CN1936711.Common blazed grating structural parameters are by centre wavelength optimization, the edge wavelength (532nm for example, the diffraction efficiency of grating of 850nm) locating reduces, even use high-octane laser, the decay of this energy also is clearly.At this moment can adopt many blazed gratings, a kind of is the many blazed gratings of broken line type, the groove face that replaces common blazed grating with the facet of two different blazing angles, the facet of two different blazing angles is worked simultaneously during work, thereby two maximal values appear on energy-wavelength curve, correspond respectively to two blaze wavelengths, curve is descended slowly at two ends, can cover bigger wavelength coverage.Because the delineation of the many blazed gratings of broken line type need be used the special cutter of scribing, and depicts two broken line type groove faces on every groove, it is less therefore only to be suitable for wire casing density, the echelette of every wire casing workplace broad.Another kind is the many blazed gratings in subregion, is the work groove face of a blazed grating is divided into two or more zones (by the wavelength number decision of required separation) delineation respectively, and each subregional wire casing density is identical, the blazing angle difference.Its essence is the amalgamation of the common blazed grating of polylith, do not have too big difficulty during delineation, can delineate the grating of higher line groove density.
Another embodiment of the present invention is as the described alignment mark structure that is used for alignment system as described in first embodiment and second embodiment of Fig. 2 and description of drawings thereof.
Another embodiment of the present invention is the described a kind of alignment methods of using above-mentioned alignment system to carry out wafer aligned of Fig. 1-Fig. 9 and description of drawings thereof.
Another embodiment of the present invention is the lithographic equipment that adopts above-mentioned alignment system, referring to Fig. 1-9 and description of drawings thereof.
Alignment system of the present invention can also be realized the measurement to the correlation parameter of lithographic equipment simultaneously, based on the positional information of alignment mark is surveyed determine in out of focus, energy, dosage, live width, contact hole size or the critical size at least one.
The present invention is described the foregoing description.The present invention is not limited only to the foregoing description, also is included in the combination of the embodiment of the invention described in the dependent claims and the change of non-intrinsically safe.Apparatus and method of the present invention specifically are applied to but are not limited to the manufacturing of integrated circuit (IC), this device can also be used for otherwise manufacturing, comprises MEMS (micro electro mechanical system) (MEMS) device, Micro-Opto-Electro-Mechanical Systems (MOEMS) device, integrated optics system, LCD panel LCD, thin-film head etc.And in above-mentioned other application, " wafer " of the present invention can be replaced by more general term " substrate "." light source " and " light beam " involved among the present invention comprises all types of electromagnetic radiation, for example: KrF excimer laser (wavelength 248nm), ArF excimer laser (wavelength 193nm), F 2Laser instrument (wavelength 157nm), Kr 2Laser instrument (wavelength 146nm), Ar 2Laser instrument (wavelength 126nm), ultrahigh pressure mercury lamp (g-line, i line), extreme ultraviolet light source (wavelength coverage of 5-20nm) or ion beam and electron beam etc.

Claims (34)

1. alignment system that is used for lithographic equipment, it is characterized in that: this system comprises at least:
Light source module is provided for the illuminating bundle of alignment system;
Lighting module, the illuminating bundle of transmission light source module, the alignment mark on the illumination wafer shines the oblong hot spot that the illuminating bundle on the wafer extends perpendicular to the direction of aligning direction for the edge;
Image-forming module, to the alignment mark imaging, it comprises the object lens and first imaging optical path at least, described module is collected the reflected light and the diffraction light of alignment mark by object lens, and is transferred to described first imaging optical path to described alignment mark imaging;
Detecting module, at least comprise with reference to grating and first and survey light path, described detecting module is surveyed light path by first and is surveyed alignment mark after the first imaging optical path imaging of image-forming module and by the transmitted light intensity with reference to Grating Modulation, obtains first light signal, second light signal and the 3rd light signal in the alignment mark scanning process;
Signal Processing and locating module are used to handle first light signal, second light signal and the 3rd light signal, and determine the center of alignment mark according to the phase information of first light signal, second light signal and the 3rd light signal.
2. the alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that: include laser cell in the described light source module.
3. the alignment system that is used for lithographic equipment as claimed in claim 2 is characterized in that: described laser cell includes phase-modulator.
4. the alignment system that is used for lithographic equipment as claimed in claim 2 is characterized in that: include laser instrument in the described laser cell, this laser instrument is gas laser, solid state laser, semiconductor laser, perhaps fiber laser.
5. the alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that: comprise the Flattened Gaussian Beams integer type device in the described light source module.
6. the alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that: described illuminating bundle is for comprising the laser lighting light beam of two discrete wavelength at least.
7. the alignment system that is used for lithographic equipment as claimed in claim 6 is characterized in that: the described laser lighting light beam that comprises two discrete wavelength at least adopts four discrete wavelength, and wherein has two wavelength at least at infrared band.
8. the alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that: the described polarization state that shines the illuminating bundle on the wafer is a circularly polarized light.
9. the alignment system that is used for lithographic equipment as claimed in claim 1, it is characterized in that: described oblong illumination hot spot is not simultaneously but along with the different moving directions of wafer station alternately produce, on wafer, form the oblong illumination hot spot that extends along the y direction in the x direction to punctual, on wafer, form the oblong illumination hot spot that extends along the x direction to punctual in the y direction.
10. the alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that: described oblong illumination hot spot is by fast gate control, and the two-way illumination path that alternate selection comprises different reshapers produces.
11. the alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that: described oblong illumination hot spot by use two alternately driven, and the LASER Light Source with difform shutter realizes; Perhaps use single LASER Light Source to realize with variable shutter.
12. the alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that: described oblong illumination hot spot realizes that by the variable illumination diaphragm of shape variable described variable illumination diaphragm comprises programmable liquid crystal light valve.
13. the alignment system that is used for lithographic equipment as claimed in claim 1, it is characterized in that: described alignment mark is the marking groove alignment mark, at least the grating that comprises three groups of different cycles: first grating, second grating and the 3rd grating, described first grating, second grating and the 3rd grating are arranged along the direction perpendicular to aligning direction, and the alignment mark that is used for x direction aligning is positioned at the marking groove of y direction, and the alignment mark that is used for y direction aligning is positioned at the marking groove of x direction.
14. the alignment system that is used for lithographic equipment as claimed in claim 13 is characterized in that: described alignment mark comprises further that also the cycle is different from the 4th grating of described first grating, second grating and the 3rd grating, the perhaps grating more than four.
15. the alignment system that is used for lithographic equipment as claimed in claim 13 is characterized in that: described first imaging optical path make first grating, second grating and the 3rd grating of forming alignment mark ± 1 order diffraction light respectively coherent imaging be positioned on the reference grating of image planes.
16. the alignment system that is used for lithographic equipment as claimed in claim 15 is characterized in that: describedly comprise three groups of amplitude gratings, correspond respectively to 1 grade of grating picture of described first grating, second grating and the 3rd grating with reference to grating; The arrangement mode of described three groups of amplitude gratings is identical with alignment mark, arranges along the direction perpendicular to aligning direction; Described three groups of amplitude gratings equal the length of corresponding 1 grade of grating picture along the length of cycle direction, perhaps greater than the length of 1 grade of grating picture of correspondence.
17. the alignment system that is used for lithographic equipment as claimed in claim 1, it is characterized in that: described first surveys light path is connected with first imaging optical path, the picture of surveying first grating, second grating and the 3rd grating of forming alignment mark obtains first light signal, second light signal and the 3rd light signal through changing with reference to the transmitted light intensity after the Grating Modulation.
18. the alignment system that is used for lithographic equipment as claimed in claim 1, it is characterized in that: described signal Processing and locating module are handled first light signal and second light signal, obtain the rough center of alignment mark according to the phase information of first light signal and second light signal; Handle the 3rd light signal,, and obtain the accurate center of alignment mark in conjunction with the rough center of alignment mark according to the phase information of the 3rd light signal.
19. the alignment system that is used for lithographic equipment as claimed in claim 1, it is characterized in that: described first imaging optical path also comprises a beam splitter, make the diffraction light of a direction of alignment mark reflect fully, the diffraction light of another perpendicular direction sees through fully.
20. the alignment system that is used for lithographic equipment as claimed in claim 19 is characterized in that: described beam splitter comprises reflector space and regional transmission, described reflector space reflects incident light fully, and described regional transmission sees through incident light fully; The distribution of described reflector space and regional transmission is that zone line is a regional transmission, and two side areas is a reflector space, or zone line is reflector space, and two side areas is a regional transmission.
21. the alignment system that is used for lithographic equipment as claimed in claim 15, it is characterized in that: describedly also comprise five groups of amplitude gratings with reference to grating, described five groups of amplitude gratings comprise one group of two-dimensional grating and are distributed in two-dimensional grating four groups of one-dimensional gratings on every side that wherein four groups of one-dimensional gratings correspond respectively to first grating of alignment mark and 1 grade of grating picture of second grating; Two-dimensional grating is corresponding to 1 grade of grating picture of the 3rd grating; Described five groups of amplitude gratings equal the length of corresponding 1 grade of grating picture along the length of cycle direction, perhaps greater than the length of 1 grade of grating picture of correspondence.
22. the alignment system that is used for lithographic equipment as claimed in claim 21 is characterized in that: described two-dimensional grating is made up of some diamond structures that are arranged in rows and columns, as the reference grating of x and y both direction aligning.
23. the alignment system that is used for lithographic equipment as claimed in claim 21 is characterized in that: the arrangement mode that is used for three groups of gratings that same direction aims in described five groups of amplitude gratings is identical with alignment mark, along the direction arrangement perpendicular to aligning direction.
24. the alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that: described image-forming module also comprises second imaging optical path, and the division line on first grating of alignment mark and the graticule is imaged on the CCD camera together.
25. a kind of alignment system that is used for lithographic equipment as claimed in claim 1, it is characterized in that: described detecting module also comprises second and surveys light path, be connected with second imaging optical path, direct detection alignment mark picture, the video that is used for the alignment mark position is monitored and manual alignment; Perhaps be used for Flame Image Process and pattern-recognition.
26. a kind of alignment system that is used for lithographic equipment as claimed in claim 1, it is characterized in that: described image-forming module also comprises the polychromatic light piece-rate system, realizes the separation of the alignment mark diffraction light of multi-wavelength.
27. a kind of alignment system that is used for lithographic equipment as claimed in claim 26 is characterized in that: described polychromatic light piece-rate system is based on dispersion element, perhaps dichroism element, the perhaps beam splitting system of diffraction optical element.
28. one kind is used for the alignment mark of alignment system according to claim 1, it is characterized in that: described alignment mark comprises the grating of three groups of different cycles at least: first grating, second grating and the 3rd grating, described first grating, second grating and the 3rd grating are arranged along the direction perpendicular to aligning direction.
29. an alignment mark as claimed in claim 28 is characterized in that: the center of first grating of described alignment mark, second grating and the 3rd grating overlaps, and whole alignment mark is the symcenter structural symmetry with this center.
30. alignment mark as claimed in claim 28, it is characterized in that: the position of first grating of described alignment mark, second grating and the 3rd grating can be changed arbitrarily, and promptly the position of any one group of grating can both be positioned at the centre or the edge of whole mark in three groups of gratings.
31. alignment mark as claimed in claim 28, it is characterized in that: described alignment mark is the marking groove alignment mark, and the alignment mark that is used for x direction aligning is positioned at the marking groove of y direction, and the alignment mark that is used for y direction aligning is positioned at the marking groove of x direction.
32. an alignment mark as claimed in claim 28 is characterized in that: described alignment mark comprises further that also the cycle is different from the 4th grating of first grating, second grating and the 3rd grating, perhaps four above gratings.
33. an alignment methods of using alignment system as claimed in claim 1 to carry out wafer aligned is characterized in that this method may further comprise the steps:
Laser lighting light beam through lighting module transmission light source module is sent forms the oblong hot spot on wafer, and the irradiation alignment mark;
Object lens by image-forming module are gathered the reflected light and the diffraction light of alignment mark, and first imaging optical path in image-forming module is to the alignment mark imaging;
Survey light path by first in the detecting module and survey alignment mark after the first imaging optical path imaging and, in the alignment mark scanning process, obtain first light signal, second light signal and the 3rd light signal by transmitted light intensity with reference to Grating Modulation;
Handle described first light signal, second light signal and the 3rd light signal through signal Processing and locating module, and determine the center of alignment mark according to the phase information of described first light signal, second light signal and the 3rd light signal.
34. a lithographic equipment that comprises alignment system as claimed in claim 1, its formation comprises:
Illuminator is used to transmit exposing light beam;
Mask platform is used to support the mask holder of mask, the alignment mark that mask pattern is arranged on the mask and have periodic structure;
Projection optical system is used for the mask pattern on the mask is projected to wafer;
Chip support and wafer station are used for supporting wafer, and the datum plate that contains reference mark is arranged on the wafer station, have the alignment mark of periodicity optical structure on the wafer;
Alignment system is used for wafer aligned and wafer station and aims at, and it is arranged between described mask platform and the described wafer station;
The coaxial alignment module is used for mask registration;
Catoptron and laser interferometer are used for mask platform and wafer station position measurement; And
By the mask platform of master control system control and the servo-drive system and the drive system of wafer station displacement drive;
It is characterized in that:
Described alignment system comprises at least: light source module is provided for the illuminating bundle of alignment system; Lighting module, the illuminating bundle of transmission light source module, the alignment mark on the illumination wafer; Image-forming module, to the alignment mark imaging, it comprises object lens and first imaging optical path at least, this module is collected the reflected light and the diffraction light of alignment mark by object lens, and is transferred to described first imaging optical path to described alignment mark imaging; Detecting module, at least comprise with reference to grating and first and survey light path, this detecting module is surveyed light path by first and is surveyed alignment mark after the first imaging optical path imaging of image-forming module and by the transmitted light intensity with reference to Grating Modulation, obtains first light signal, second light signal and the 3rd light signal in the alignment mark scanning process; Signal Processing and locating module are used to handle first light signal, second light signal and the 3rd light signal, and determine the center of alignment mark according to the phase information of first light signal, second light signal and the 3rd light signal; Described alignment mark is the marking groove alignment mark, at least the grating that comprises three groups of different cycles: first grating, second grating and the 3rd grating, described first grating, second grating and the 3rd grating are arranged along the direction perpendicular to aligning direction, and the alignment mark that is used for x direction aligning is positioned at the marking groove of y direction, and the alignment mark that is used for y direction aligning is positioned at the marking groove of x direction; The oblong hot spot that the described illuminating bundle that shines on the wafer extends perpendicular to the direction of aligning direction for the edge.
CN2008100354053A 2008-03-31 2008-03-31 Aligning system, mark, method for lithographic device and lithographic device thereof Active CN101251725B (en)

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