CN101135860A - Light scribing device and Aligning system and aligning method used for light scribing device - Google Patents
Light scribing device and Aligning system and aligning method used for light scribing device Download PDFInfo
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- CN101135860A CN101135860A CNA2007100455806A CN200710045580A CN101135860A CN 101135860 A CN101135860 A CN 101135860A CN A2007100455806 A CNA2007100455806 A CN A2007100455806A CN 200710045580 A CN200710045580 A CN 200710045580A CN 101135860 A CN101135860 A CN 101135860A
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Abstract
The system comprises: a light source module, a lighting module, an imaging module, a detection module and a signal processing and positioning module. The imaging module is used for collecting the reflected light and diffracted light of the alignment mark to form a first optical path and a second imaging optical path; after said alignment mark is imaged through the first and second imaging optical path, it is modulated by a first reference grating and second reference grating; the detection module detects the strength of the transmitting light of the alignment mark after modulated by the first reference grating and the strength of the transmitting light of the alignment mark after modulated by the second reference grating to get a first light signal and a second light signal; the signal processing and positioning module uses the amplitude information of the first light signal and the phase information of the second light signal to confirm the location information of the alignment mark.
Description
Technical field
The present invention is relevant with the lithographic equipment that integrated circuit or other microdevice are made the field, relates to a kind of lithographic equipment and the alignment system and the alignment methods that are used for 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, Ф
Wz), and the coordinate (X of mask in coordinate system of machine
R, Y
R, Ф
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 alignment so that adopts of lithographic equipment is a grating alignment.Grating alignment is meant that even illumination beam on the grating alignment mark diffraction takes place, and the emergent light behind the diffraction carries the full detail about alignment mark structure.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) simultaneously in picture plane interference imaging, through photodetector and signal Processing, determine the centering adjustment position.
A kind of situation of prior art is (referring to Chinese invention patent, application number: CN03164859.2, denomination of invention: the alignment system and the method that are used for etching system), 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 separation of multi-level diffraction light, distinguish coherent imaging in image planes; The registration signal of ruddiness and green glow is separated by a polarization beam splitter prism; See through the transmitted light intensity of the reference grating in corresponding cycle behind the detection alignment mark multilevel diffraction light coherent imaging, in the alignment mark scanning process, obtain the registration signal of sinusoidal output, obtain the center of alignment mark by the phase information of the signal of different frequency.
Senior the diffraction light of such alignment system by snoop tag also can partly suppress the signal attenuation influence that destructive interference causes to reduce the influence of alignment mark asymmetrical deformation by the dual wavelength illumination.But, owing to only used the LASER Light Source of two kinds of visible wavelengths, in fact to eliminate the problem of signal attenuation that destructive interference causes fully and need to adopt 4-5 illumination wavelengths at least, and the dielectric material of low k value can cause the decay of registration signal intensity in the absorption of limit of visible spectrum, thereby influences alignment precision.In addition, adopt voussoir array or wedge to make up separation and the coherent imaging of realizing multi-level diffraction light.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.
The situation of another kind of prior art is (referring to Chinese invention patent, application number: CN03133004.5, denomination of invention: lithographic equipment and device making method), another off-axis alignment system that Holland ASML company is adopted, this alignment system produces the overlapping alignment mark picture of two rotations ± 90 degree (Rotate 180 degree relatively) by a rotation self-reference interferometer, survey just overlapping at pupil plane, the interference signal of the negative order of diffraction, during mark scannng, the interference signal intensity of different diffraction level time is with different frequency change, obtains aligned position information according to the phase change of each order of diffraction time interference signal.This alignment system has adopted the rotation self-reference interferometer of many principal sections, space compound prism structure, the processing of prism and to debug tolerance very high, and prism group gummed difficulty is bigger.This system adopts the single blazed grating with centre wavelength optimization to carry out heterogeneous light separation, can cause the reduction of other coloured light diffraction efficiencies of edge wavelength, thereby cause the decay of registration signal intensity, influences alignment precision.
Summary of the invention
The lithographic equipment that the object of the present invention is to provide a kind of improved alignment system, is used for the alignment methods of wafer aligned and has this alignment system, this alignment system can provide high alignment precision, Technological adaptability and stability.
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 object lens and two imaging optical paths at least, this module is collected the reflected light and the diffraction light of alignment mark by object lens, and forms first imaging optical path and second imaging optical path;
Detecting module comprise at least first survey light path, second survey light path, first with reference to grating and second with reference to grating, 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 first transmitted light intensity with reference to Grating Modulation, obtains first light signal in the alignment mark scanning process; Second surveys light path surveys alignment mark after the second imaging optical path imaging of image-forming module and by second transmitted light intensity with reference to Grating Modulation, obtains second light signal in the alignment mark scanning process;
Signal Processing and locating module are used to handle first light signal and second light signal, and determine the positional information of alignment mark in conjunction with the phase information of the amplitude information of first light signal and second light signal.
Include laser cell in the described light source module.
Described laser cell includes phase-modulator.
Include laser instrument in the described laser cell, this laser instrument can be gas laser, solid state laser, semiconductor laser, perhaps fiber laser.
Described illuminating bundle is the multiwavelength laser illuminating bundle.
Described multiwavelength laser illuminating bundle comprises two discrete wavelength at least.
Described multiwavelength laser illuminating bundle is preferential to adopt four discrete wavelength, and wherein has two wavelength at least near infrared or infrared band.
Comprise the Flattened Gaussian Beams integer type device in the described lighting module.
The described illuminating bundle that shines on the wafer is a circularly polarized light.
Described first imaging optical path is to the many groups grating coherent imaging in the multicycle grating of forming alignment mark.
Described second imaging optical path is to one group of grating coherent imaging of the cycle minimum in the multicycle grating of forming alignment mark.
The intermediary image position of described first imaging optical path is provided with first spatial filter, make many groups grating in the multicycle grating of forming alignment mark ± 1 order diffraction light can pass through.
Described first spatial filter can also make other a specific orders time diffraction light of many group gratings in the multicycle grating of forming alignment mark pass through.
The intermediary image position of described second imaging optical path is provided with second spatial filter, make cycle minimum in the multicycle grating of forming alignment mark one group of grating ± 1 order diffraction light can pass through.
Described image-forming module can also comprise a beam splitter, and a part of grating diffration light reflects fully in the multicycle grating of feasible composition alignment mark, and another part grating diffration light sees through fully.
Described image-forming module also comprises the 3rd imaging optical path, to the alignment mark direct imaging, is used for the video monitoring and the manual alignment of alignment mark position; Perhaps be used for Flame Image Process and pattern-recognition, auxiliary aligning automatically.
Described image-forming module also comprises the polychromatic light piece-rate system, realizes the separation of the alignment mark diffraction light of multi-wavelength.
Described polychromatic light piece-rate system is based on dispersion element, perhaps dichroism element, the perhaps beam splitting system of diffraction optical element.
Described detecting module also comprises the 3rd and surveys light path, direct detection alignment mark picture, and 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, auxiliary aligning automatically.
Described first is amplitude type multicycle optical grating construction with reference to grating.
Described second is amplitude type monocycle optical grating construction with reference to grating.
A kind of alignment methods of using alignment system to carry out wafer aligned, wherein, this method may further comprise the steps: the laser lighting light beam that sends through lighting module transmission light source module, and be radiated at alignment mark on the wafer; 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 and second imaging optical path are respectively to the alignment mark coherent imaging; Survey light path by first in the detecting module and survey alignment mark after the first imaging optical path imaging and by first the transmitted light intensity with reference to Grating Modulation, in the alignment mark scanning process, obtain first light signal, survey light path by second and survey alignment mark after the second imaging optical path imaging and, in the alignment mark scanning process, obtain second light signal by second the transmitted light intensity with reference to Grating Modulation; Handle first light signal and second light signal through signal Processing and locating module, determine the positional information of alignment mark in conjunction with the phase information of the amplitude information of first light signal and second light signal.
A kind of lithographic equipment that comprises alignment system, 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 unit 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, described alignment mark is the multicycle optical grating construction, comprises the grating of many group different cycles; Described alignment system comprises at least: the light source module and the lighting module that provide and transmit the multiwavelength laser illuminating bundle; Be used to gather the reflected light and the diffraction light of alignment mark, and make the image-forming module of diffraction light coherent imaging; Be used to separate the polychromatic light piece-rate system of multi-wavelength diffraction light; Be used to survey the detecting module of alignment mark picture through the light signal of reference Grating Modulation; Signal Processing and the locating module handling light signal and determine the alignment mark positional information in conjunction with the amplitude and the phase information of light signal; Wherein, the amplitude information of described light signal from the multicycle grating of forming alignment mark many groups grating coherent imaging after the amplitude type multicycle obtain with reference to the transmitted light intensity of Grating Modulation; One group of grating coherent imaging of phase information cycle minimum from the multicycle grating of forming alignment mark after the amplitude type monocycle obtain with reference to the transmitted light intensity of Grating Modulation.
Compared with prior art, the present invention has the following advantages and good effect:
1, alignment system of the present invention adopts phase detection and amplitude to survey principle of combining, and higher alignment precision can be provided.Coarse alignment adopts the amplitude Detection Techniques, based on multicycle grating marker imaging, survey simultaneously the multicycle grating marker many groups optical grating diffraction light coherent imaging after the multicycle with reference to the transmitted light intensity of Grating Modulation, determine the coarse alignment position by the amplitude information of transmitted light intensity; Fine alignment adopts the phase detection technology, one group of grating diffration light coherent imaging of a detect cycle minimum after the monocycle with reference to the transmitted light intensity of Grating Modulation, determine accurate aligned position by the phase information of transmitted light intensity.
2, the alignment mark of multicycle optical grating construction of the present invention, wherein, one group of grating diffration light of cycle minimum is used for fine alignment, because the fine alignment grating has adopted less live width, help improving alignment precision, have stronger Technological adaptability simultaneously, can reduce of the influence of mark asymmetrical deformation alignment precision; Many group grating diffration light are used for coarse alignment in the multicycle grating of composition alignment mark, can increase the mark capturing scope.
3, the present invention uses the coherent imaging optical system based on two 4f system architectures, by different spatial filters is set in intermediate image plane, to the many groups grating in the multicycle grating of forming alignment mark and wherein one group of grating of cycle minimum realize coherent imaging respectively, make the diffraction light of same alignment mark can be used for the fine alignment and the coarse alignment position sensing of alignment mark simultaneously.
4,, and wherein have two wavelength at least near infrared or infrared band because the present invention uses the multiwavelength laser illuminating bundle of four discrete wavelength.Use the multi-wavelength illuminating bundle, can suppress the influences of interfering cancellation effect more on the one hand, improved Technological adaptability; On the other hand, adopt the illuminating bundle of near infrared and infrared band can effectively solve the absorption problem of the dielectric material of low k value, and can be used for the marker detection of polysilicon process layer, improve registration signal intensity in limit of visible spectrum.
5, this alignment system can produce the registration signal with strong Technological adaptability, sensitivity and high s/n ratio.
Description of drawings
By the embodiment of the invention and in conjunction with the description of its accompanying drawing, can further understand purpose, specific structural features and the advantage of its invention.Wherein, accompanying drawing is:
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 is the synoptic diagram of wafer alignment marks among Fig. 1;
Fig. 3 is the synoptic diagram of the sub-structure of alignment mark of the present invention;
Fig. 4 is the system architecture synoptic diagram of alignment system first embodiment of the present invention;
Fig. 5 is that first of alignment system first embodiment of the present invention surveys first in the light path with reference to the grating synoptic diagram;
Fig. 6 is the first light signal synoptic diagram of alignment system first embodiment of the present invention;
Fig. 7 is that second of alignment system first embodiment of the present invention surveys second in the light path with reference to the grating synoptic diagram;
Fig. 8 is the second light signal synoptic diagram of alignment system first embodiment of the present invention;
Fig. 9 is the optical principle synoptic diagram of alignment system first embodiment of the present invention;
Figure 10 is the optical principle synoptic diagram of alignment system second embodiment of the present invention.
Embodiment
Fig. 1 is a kind of alignment system of lithographic equipment and total arrangement, principle of work structural representation between this alignment system and the existing lithographic equipment of being used for of lithographic equipment of the present invention.As shown in Figure 1, the formation of lithographic equipment comprises: be used to provide exposing light beam illuminator 1, be provided with mask pattern and have periodic structure alignment mark RM mask 2, be used to support mask 2 mask platform 3, be provided with the wafer 6 of the alignment mark WM of periodicity optical structure, the projection optical system 4 that is used for the wafer station 7 of supporting wafer 6 and is used for the mask pattern on the mask 2 is projected to wafer 6.The datum plate 8 that is carved with reference mark FM is arranged on the wafer station 7.In addition, this lithographic equipment also comprise be used for mask and wafer aligned from shaft type alignment system 5, be used to measure the catoptron 10,16 and the interferometer 11,15 of mask platform 3 and wafer station 7 positions, control mask platform 3 and the servo-drive system 13 of wafer station 7 displacements and the master control system 12 of drive system 9,14 and Control Servo System 13 and drive system 9,14.
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, and the mask alignment mark RM 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 mask pattern becomes to dwindle on the wafer 6 that is coated with photoresist through projection optical system 4.
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.
Fig. 2 is the synoptic diagram of wafer alignment marks among Fig. 1.As shown in the figure, the alignment mark WM of wafer 6 is that multicycle phase grating structure (has only provided the alignment mark of x direction among the figure, the alignment mark of y direction is similar), whole alignment mark structure symmetry, the grating that comprises many group different cycles, one group of middle grating cycle minimum, the some groups of grating cycles that are arranged in both sides increase successively.For example, alignment mark is by the optical grating constitution of three kinds of different cycles, and the middle one group grating cycle is P1, and the grating cycle that is arranged in both sides respectively is P
2And P
3, and P
1＜P
2＜P
3, then the grating distribution situation of whole alignment mark is P
3, P
2, P
1, P
2, P
3For example, grating P
1Cycle can be 2 μ m, dutycycle is 1: 1; Grating P
2Cycle be 3 μ m, grating P
3Cycle be about 5 μ m.By optimizing grating P
1Periodicity, grating P
2And P
3Cycle, dutycycle, periodicity and respectively organize interval between grating, can be so that registration signal be more conducive to the position probing of multicycle grating alignment mark.In addition, one group of grating cycle maximum in the middle of the structure of multicycle grating also can make, the some groups of grating cycles that are arranged in both sides reduce successively.For example, the middle one group grating cycle is P
3, the grating cycle on both sides respectively is P
2And P
1, and P
3P
2P
1, then the grating distribution situation of whole alignment mark is P
1, P
2, P
3, P
2, P
1Further, the multicycle grating marker can also include the grating in the 4th kind of cycle or more other cycles.
At the alignment mark asymmetrical deformation that CMP and metal sputtering (Al-PVD) cause, grating P that can be bigger to live width in the alignment mark
3Segment, with enhanced process adaptability.As shown in Figure 3, grating P
3Lines segmentations mode can have two kinds, a kind of is along the direction segmentation of grating cycle, another kind is perpendicular to the direction segmentation of grating cycle, and the segmentation optical grating construction cycle, the diffraction light that therefore segments the optical grating construction generation can not enter object lens less than the resolution of aiming at object lens.According to technological requirement, any one group of grating can segment in the multicycle grating.The alignment mark of this form with sub-structure is also in protection scope of the present invention.The size of entire wafer alignment mark WM is less, is suitable for narrower marking groove, for example is 40 μ m * 160 μ m.
Fig. 4 is the system architecture synoptic diagram of alignment system 5 first embodiment of the present 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 RF phase-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 (509,530,513), spatial filter (512,514,520), polychromatic light piece-rate system (515,521) and imaging optical system (532,516,522).Detecting module comprises with reference to grating (517,523) and photodetector (519,525).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 5 is, adopts phase detection and amplitude to survey the method that combines, and alignment mark is multiply periodic phase grating structure.Coarse alignment adopts the amplitude Detection Techniques, based on multicycle grating marker imaging, survey to form simultaneously many group gratings in the multicycle grating of alignment mark ± 1 order diffraction light (or other a specific orders time diffraction light) coherent imaging after the multicycle with reference to grating after the light intensity of transmission, obtain the rough center of whole alignment mark by the amplitude information of the light intensity signal that sees through; Can produce preferably registration signal to improve the coarse alignment precision by optimizing alignment mark dependency structure parameter.Fine alignment adopts phase detection technology, one group of grating P of a detect cycle minimum
1± see through the light intensity of monocycle behind the 1 order diffraction light coherent imaging with reference to grating, obtain accurate aligned position by the phase information of transmitted light intensity.Because fine alignment mark live width is less, improved alignment precision on the one hand, have stronger Technological adaptability on the other hand, can reduce of the influence of alignment mark asymmetrical deformation to alignment precision; Many group grating diffration light are used for coarse alignment in the multicycle grating of composition alignment mark, can increase the mark capturing scope.Fine alignment and coarse alignment signal obtain simultaneously through single pass, and the detecting module of fine alignment and coarse alignment separates on the hardware, and illumination and image-forming module are shared.
This alignment system 5 can produce the registration signal with strong Technological adaptability, high sensitivity and high s/n ratio, and alignment system 5 repeatability precisions can reach about 3～5nm, satisfy fully live width 90nm and 90nm following to alignment request.
Referring to Fig. 4, the light source module of alignment system 5 provides the laser lighting that comprises a plurality of discrete wavelength light source, comprises the LASER Light Source of two discrete wavelength at least, for example, and 632.8nm and 785nm; The preferential LASER Light Source that adopts four discrete wavelength, and wherein have two wavelength at least near infrared or infrared band, for example: 532nm, 632.8nm, 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.
Include the laser cell (not shown) in the light source module,, 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 for improving signal to noise ratio (S/N ratio).Employed LASER Light Source can be gas laser, solid state laser, semiconductor laser, perhaps fiber laser etc.
Above-mentioned alignment system 5 uses the multi-wavelength illuminating bundle, can suppress the influence of the interference cancellation effect of many process layers generations, improves Technological adaptability; Use the light illumination of near infrared and infrared wavelength, can effectively solve the absorption problem of the dielectric material of low k value, and can be used for the marker detection of polysilicon process layer, thereby improve registration signal intensity in limit of visible spectrum.
As shown in Figure 4, lighting module comprises Transmission Fibers 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 polarization beam splitting face 509a through polarization beam apparatus 509 impinges perpendicularly on image-forming module then.511 form the Kohler illumination system from aperture diaphragm 507 to object lens.In addition, also comprise Flattened Gaussian Beams (Flat-topGaussian beam) reshaper (not shown) in the lighting module, be used for Gauss beam reshaping is become Flattened Gaussian Beams.
Image-forming module comprises first imaging optical path (being the coarse alignment light path), second imaging optical path (being the fine alignment light path) and the 3rd imaging optical path (being the CCD imaging optical path).Wherein, first imaging optical path is to the many groups grating image in the multicycle grating of forming alignment mark, and second imaging optical path is to one group of grating image of the cycle minimum in the multicycle grating of forming alignment mark.First imaging optical path and second imaging optical path are imaged on alignment mark first and second respectively with reference on the grating, be used for coarse alignment and fine alignment, wherein first is amplitude type multicycle optical grating construction with reference to grating, and second is amplitude type monocycle optical grating construction with reference to grating.The 3rd imaging optical path on CCD camera photosurface, is used for the monitoring of manual alignment and video with alignment mark and division line direct imaging on the one hand, also can carry out Flame Image Process and pattern-recognition on the other hand.
Detecting module comprises that first surveys light path (being that coarse alignment is surveyed light path), the second detection light path (being that fine alignment is surveyed light path) and the 3rd detection light path (being that ccd image is surveyed light path), corresponds respectively to first imaging optical path, second imaging optical path and the 3rd imaging optical path; Also comprise first with reference to grating and second with reference to grating.
In wafer station 7 scanning processes, first imaging optical path is to many group grating coherent imagings in the multicycle grating of forming alignment mark, first surveys light path surveys multicycle grating picture through multiply periodic first with reference to the transmitted light intensity summation after the Grating Modulation, obtains first light signal.Second imaging optical path is to one group of grating coherent imaging of cycle minimum in the multicycle grating of forming alignment mark, surveys light path by second and surveys monocycle grating picture through monocyclic second with reference to the transmitted light intensity after the Grating Modulation, obtains second light signal.The 3rd surveys the picture that light path adopts CCD camera detection alignment mark and 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 auxiliary aligning automatically.
Illuminating bundle impinges perpendicularly on through object lens 511 on the grating type alignment mark WM of wafer 6, and reflection and diffraction take place.Object lens 511 are to aim at key element in the image-forming module, and these lens must have the multilevel diffraction light of enough big numerical aperture (for example NA=0.8) with the different color light of collecting to go up from wafer alignment mark WM.When NA=0.8, if use the lighting source of wavelength 850nm, then can detect the cycle and be 1.1 μ m the grating alignment mark ± 1 order diffraction light.In addition, suitable distance is arranged, the object lens of preferred long working distance for guaranteeing wafer 6 and 5 of alignment systems.
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 hot spot that incides on the wafer 6 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.
Reflection and diffraction take place in multi-wavelength illuminating bundle illumination wafer alignment marks WM, produce a series of diffraction patterns on the frequency plane of object lens 511, respectively the grating part of alignment mark WM different cycles.Alignment mark WM multicycle grating diffration light enters beam splitter 530 behind object lens 511 collimations, 530a is divided into two-way through beam-splitting surface, and one the tunnel enters the 3rd imaging optical path, and another road enters first and second imaging optical paths.
The 3rd imaging optical path, be in the CCD imaging optical path, the a part of light beam that comprises multi-wavelength diffraction light and zero order light reflected is through a flat board 531 that is carved with division line, through lens 532 and Transmission Fibers 533 alignment mark and division line are imaged on the CCD camera 534 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 arranged in the coarse alignment light path, does not at this time comprise zero order light in the imaging beam, can be monochromatic light imaging or polychromatic light imaging.
First and second imaging optical paths are automatic optical system for alignment, and first imaging optical path is the coarse alignment light path, produce first light signal (being the coarse alignment signal); Second imaging optical path is the fine alignment light path, produces second light signal (being the fine alignment signal).The multi-wavelength diffraction light that enters automatic optical system for alignment is at first through a spatial filter 512, and the zero order light of multi-wavelength diffraction light is filtered, and through the beam-splitting surface 513a of beam splitter 513 separated into two parts, enters first imaging optical path and second imaging optical path respectively then.
Wherein a part of multi-wavelength diffraction light through beam-splitting surface 513a beam splitting enters into first imaging optical path (being the coarse alignment light path), at first through first spatial filter 514, makes on the one hand many groups grating of forming the multicycle grating marker (grating P for example
1, P
2And P
3) ± 1 order diffraction light (or other a specific orders time diffraction light) can pass through, and zero order light, other level time diffraction light and parasitic light are filtered, and eliminate the parasitic light cross talk effects of contiguous mark on the wafer or product structure on the other hand.Many groups grating of the multi-wavelength that sees through ± 1 order diffraction light (or other a specific orders time diffraction light) is through a polychromatic light piece-rate system 515, makes the diffraction light of different colours separate, and only provided wherein a kind of wavelength X among Fig. 4
1Light path, wavelength is λ
1The multi-period mark diffraction light through lens 516, the different cycles grating ± the corresponding coherent imaging of 1 order diffraction light, make the multicycle grating image be positioned at the first imaging optical path image planes position first with reference to grating 517 on.
Referring to Fig. 5, first is similar with alignment mark WM with reference to grating 517, is multiply periodic amplitude grating structure (only provided the reference grating of x direction among the figure, the reference grating of y direction is similar).In wafer station 7 scanning processes, the picture of multicycle grating scans through first with reference to grating 517, by optical fiber 518, adopt photodetector 519 survey multicycle grating pictures through first with reference to the transmitted light intensity after grating 517 modulation, be optimized by structure multi-period mark, can obtain first light signal (being the coarse alignment signal) as shown in Figure 6, center position at mark, the coarse alignment signal has a main peak, and the amplitude of main peak and secondary peak has notable difference, make the center of main peak relatively easily detect, can obtain a rough markers align center X by the amplitude of surveying whole coarse alignment signal
01, the error of coarse alignment is less than 1/2 cycle of fine alignment signal.The capture range of coarse alignment is relevant along the length of cycle direction with alignment mark WM, by increasing the periodicity of alignment mark WM, can increase the capture range of coarse alignment.
Another part multi-wavelength diffraction light through the beam-splitting surface 513a of beam splitter 513 beam splitting enters second imaging optical path (being the fine alignment light path), at first through second spatial filter 520, makes that having only one group of grating of cycle minimum (is grating P
1) ± 1 order diffraction light passes through grating P
iZero order light and senior diffraction light and grating P
2And P
3All level time diffraction lights all filtered, eliminate the parasitic light cross talk effects of contiguous mark on the wafer or product structure simultaneously.The grating P that sees through
1Multi-wavelength ± 1 order diffraction light through a polychromatic light piece-rate system 521, make the diffraction light of different colours separate, only provided wherein a kind of wavelength X among Fig. 4
1Light path, grating P
1± 1 order diffraction light through lens 522 coherent imagings be positioned at the second imaging optical path image planes position second with reference to grating 523 on.
Referring to Fig. 7, second the grating P with reference to grating 523 and alignment mark WM
1Similar, be the amplitude grating that monocycle and dutycycle equaled 1: 1.In wafer station 7 scanning processes, grating P
1Picture scanning through second with reference to grating 523, by optical fiber 524, adopt photodetector 525 survey monocycle grating pictures through second with reference to the transmitted light intensity after grating 523 modulation, can obtain second light signal (being the fine alignment signal) as shown in Figure 8, this signal is the sinusoidal periodic signal with multi-peak characteristic.Because the capture range of fine alignment be ± 1/2 times fine alignment signal period, so according to the centering adjustment position X of coarse alignment signal
01, can be in the fine alignment signal with coarse alignment position X
01For the center ± obtain a unique peak in 1/2 periodic regime, this position is the centering adjustment position X of fine alignment
02
Intermediate image plane (frequency plane) position of alignment mark is provided with spatial filter 514 and 520 respectively in first imaging optical path and second imaging optical path, (or other a specific orders time diffraction light) can be passed through, eliminate the parasitic light cross talk effects of being close to mark or product structure on the wafer on the other hand.The wafer surface that causes for metal sputtering is coarse, has only the light of particular space frequency to pass through by optimizing the spatial filter 514 and 520 in the light path, making, can suppress the noise that metallic particles causes, improves signal to noise ratio (S/N ratio).
Fig. 9 is that the optical principle synoptic diagram of alignment system first embodiment of the present invention is (with the monochromatic wavelength X in the multi-wavelength illuminating bundle
1Light path is an example), comprise two coherence imaging systems (the 4f system architecture of being familiar with this professional domain personnel among Fig. 9 is represented) on this optical system structure.The illuminating bundle that light source 540 sends impinges perpendicularly on the alignment mark 543 that is positioned at preceding group lens 542 front focal planes through the preceding group of lens 542 (being the object lens 511 among Fig. 4) of catoptron 541 and coherence imaging system, alignment mark 543 is multicycle optical grating construction (referring to Fig. 2), and for example: the middle grating cycle is P
1, the grating cycle on both sides respectively is P
2And P
3, and P
1＜P
2＜P
3Form many groups grating in the multicycle grating of alignment mark ± 1 order diffraction light through preceding group of lens 542 after, through beam splitter 544 separated into two parts, a part enters the coarse alignment light path again, another part enters the fine alignment light path.Constitute first coherence imaging system (coherence imaging system of coarse alignment) by preceding group of lens 542, first spatial filter 545 and the first back group lens 546; Preceding group lens 542, second spatial filter 548 and the second back group lens 549 constitute second coherence imaging systems (coherence imaging system of fine alignment).
The intermediate image plane of first coherence imaging system (being frequency plane) is provided with first spatial filter 545, make to form many groups grating (grating P for example of multicycle grating marker
1, P
2And P
3) ± 1 order diffraction light (or other a specific orders time diffraction light) can pass through; The intermediate image plane of second coherence imaging system (being frequency plane) is provided with second spatial filter 548, makes one group of grating having only the cycle minimum (grating P for example
1) ± 1 order diffraction light can pass through.
Simultaneously, different reference gratings is set respectively on the image planes of two coherence imaging systems, the image planes of first coherence imaging system be provided with that amplitude type multicycle grating forms first with reference to grating 547 (referring to Fig. 5); The image planes of second coherence imaging system be provided with amplitude type monocycle grating second with reference to grating 550 (referring to Fig. 7).In wafer station 7 scanning processes, the grating P of multicycle grating marker
1, P
2And P
3± 1 grade of (or other a specific order time) diffraction light, first spatial filter 545 by first coherence imaging system, group lens 546 are at the image planes coherent imaging through first after, and multicycle grating picture forms first light signal through first with reference to behind the grating 547.One group of grating P of cycle minimum
1± second spatial filter 548 of 1 order diffraction light by second coherence imaging system, group lens 549 are at the image planes coherent imaging through second after, and monocycle grating picture forms second light signal through second with reference to behind the grating 550.Determine the center of alignment mark according to the phase information of the amplitude information of first light signal and second light signal.
Figure 10 is the optical principle synoptic diagram of alignment system second embodiment of the present invention, and is same with the monochromatic wavelength X in the multi-wavelength illuminating bundle
1Light path is an example, on this optical system structure also is to comprise two coherence imaging systems (representing with the 4f system architecture among Figure 10).
The illuminating bundle that light source 560 sends impinges perpendicularly on the alignment mark 563 that is positioned at preceding group lens 562 front focal planes through the preceding group of lens 562 (being the object lens 511 among Fig. 4) of catoptron 561 and coherence imaging system, and alignment mark 563 is multicycle optical grating construction (referring to Fig. 2).Form many groups grating in the multicycle grating of alignment mark ± 1 order diffraction light through preceding group of lens 562 after, through beam splitter 564 separated into two parts, a part enters the coarse alignment light path again, another part enters the fine alignment light path.The beam-splitting surface 564a of beam splitter 564 adopts special plated film design or job operation, makes the low frequency grating that incides the beam-splitting surface center section (grating P for example
2And P
3) diffraction light reflect fully, enter the coarse alignment light path; Incide high-frequency grating (the grating P for example of beam-splitting surface marginal portion
1) diffraction light see through fully, enter the fine alignment light path.Can increase the contrast of the positive and negative level time diffraction light coherent imaging of two coherent imaging light paths by this beam splitting mode, improve the signal to noise ratio (S/N ratio) of registration signal.Otherwise, low frequency grating diffration light is seen through fully, the diffraction light of high-frequency grating reflects fully.
Constitute first coherence imaging system (coherence imaging system of coarse alignment) by preceding group of lens 562, first spatial filter 565 and the first back group lens 566; Preceding group lens 562, second spatial filter 568 and the second back group lens objectives 569 constitute second coherence imaging systems (coherence imaging system of fine alignment).The intermediate image plane of first coherence imaging system (being frequency plane) is provided with first spatial filter 565, make to form many groups grating (grating P for example of multicycle grating marker
2And P
3) ± 1 order diffraction light (or other a specific orders time diffraction light) can pass through; The intermediate image plane of second coherence imaging system (being frequency plane) is provided with second spatial filter 568, makes one group of grating having only the cycle minimum (grating P for example
1) ± 1 order diffraction light can pass through.Simultaneously, the image planes of first coherence imaging system be provided with by amplitude type multicycle grating form first with reference to grating 567 (referring to Figure 10); The image planes of second coherence imaging system be provided with amplitude type monocycle grating second with reference to grating 570 (referring to Fig. 7 and Figure 10).Compare with reference to grating 547 (be among Fig. 5 first embodiment first with reference to grating 517) with first among Fig. 9, first among Figure 10 with reference to the center section of grating 567 (corresponding to the grating P of alignment mark 563
1Part) be light tight zone, the optical grating construction of the right and left and how all grating marks 563 grating P
2, P
3Structural similarity.
In wafer station 7 scanning processes, the grating P of multicycle grating alignment mark 563
2And P
3± 1 grade of (or other a specific order) diffraction light is by behind first spatial filter 565 of first coherence imaging system, and at the image planes coherent imaging, multicycle grating picture sees through first with reference to behind the grating 567, forms first light signal.One group of grating P of cycle minimum
1± second spatial filter 568 of 1 order diffraction light by second coherence imaging system, at the image planes coherent imaging, monocycle grating picture sees through second with reference to behind the grating 570, forms second light signal.Can determine the center of alignment mark according to the phase information of the amplitude information of first light signal and second light signal.
Alignment system of the present invention can adopt two discrete wavelength the laser lighting light source (for example: 632.8nm, 785nm), at this time can utilize the beam splitting system of a polarization beam apparatus and λ/4 wave plate combined to realize separating of two wavelength light beams.When the lighting source that adopts four discrete wavelength (for example: 532nm, 632.8nm, 785nm, when 850nm) throwing light on alignment mark simultaneously, the diffraction light of different wave length is overlapped, therefore, the signal of different wave length must separate detection.Can only separate the coloured light of two kinds of wavelength based on polarization beam splitter prism,, therefore need to use other polychromatic light piece-rate system to separate wavelength optical signals then powerless more than two kinds of registration signal more than the wavelength.
Among the present invention, polychromatic light piece-rate system 515 and 521 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.
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), F2 laser instrument (wavelength 157nm), Kr2 laser instrument (wavelength 146nm), Ar2 laser 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 (23)
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;
Image-forming module, to the alignment mark imaging, it comprises object lens and two imaging optical paths at least, this module is collected the reflected light and the diffraction light of alignment mark by object lens, and forms first imaging optical path and second imaging optical path;
Detecting module comprise at least first survey light path, second survey light path, first with reference to grating and second with reference to grating, 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 first transmitted light intensity with reference to Grating Modulation, obtains first light signal in the alignment mark scanning process; Second surveys light path surveys alignment mark after the second imaging optical path imaging of image-forming module and by second transmitted light intensity with reference to Grating Modulation, obtains second light signal in the alignment mark scanning process;
Signal Processing and locating module are used to handle first light signal and second light signal, and determine the positional information of alignment mark in conjunction with the phase information of the amplitude information of first light signal and second light signal.
2. a kind of alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that, includes laser cell in the described light source module.
3. a kind of alignment system that is used for lithographic equipment as claimed in claim 2 is characterized in that described laser cell includes phase-modulator.
4. a kind of alignment system that is used for lithographic equipment as claimed in claim 2 is characterized in that, includes laser instrument in the described laser cell, and this laser instrument can be gas laser, solid state laser, semiconductor laser, perhaps fiber laser.
5. a kind of alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that described illuminating bundle is the multiwavelength laser illuminating bundle.
6. a kind of alignment system that is used for lithographic equipment as claimed in claim 5 is characterized in that described multiwavelength laser illuminating bundle comprises two discrete wavelength at least.
7. a kind of alignment system that is used for lithographic equipment as claimed in claim 5 is characterized in that, described multiwavelength laser illuminating bundle is preferential to adopt four discrete wavelength, and wherein has two wavelength at least near infrared or infrared band.
8. a kind of alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that, comprises the Flattened Gaussian Beams integer type device in the described lighting module.
9. a kind of alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that, the described illuminating bundle that shines on the wafer is a circularly polarized light.
10. a kind of alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that, described first imaging optical path is to the many groups grating coherent imaging in the multicycle grating of forming alignment mark.
11. a kind of alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that, described second imaging optical path is to one group of grating coherent imaging of the cycle minimum in the multicycle grating of forming alignment mark.
12. a kind of alignment system that is used for lithographic equipment as claimed in claim 1, it is characterized in that, the intermediary image position of described first imaging optical path is provided with first spatial filter, make many groups grating in the multicycle grating of forming alignment mark ± 1 order diffraction light can pass through.
13. a kind of alignment system that is used for lithographic equipment as claimed in claim 12 is characterized in that, described first spatial filter can also make other a specific orders time diffraction light of many group gratings in the multicycle grating of forming alignment mark pass through.
14. a kind of alignment system that is used for lithographic equipment as claimed in claim 1, it is characterized in that, the intermediary image position of described second imaging optical path is provided with second spatial filter, make cycle minimum in the multicycle grating of forming alignment mark one group of grating ± 1 order diffraction light can pass through.
15. 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 can also comprise a beam splitter, a part of grating diffration light reflects fully in the multicycle grating of feasible composition alignment mark, and another part grating diffration light sees through fully.
16. a kind of alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that described image-forming module also comprises the 3rd imaging optical path, to the alignment mark direct imaging, is used for the video monitoring and the manual alignment of alignment mark position; Perhaps be used for Flame Image Process and pattern-recognition, auxiliary aligning automatically.
17. a kind of alignment system that is used for lithographic equipment as claimed in claim 1 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.
18. a kind of alignment system that is used for lithographic equipment as claimed in claim 17 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.
19. a kind of alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that, described detecting module also comprises the 3rd and surveys light path, direct detection alignment mark picture, and 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, auxiliary aligning automatically.
20. a kind of alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that, described first is amplitude type multicycle optical grating construction with reference to grating.
21. a kind of alignment system that is used for lithographic equipment as claimed in claim 1 is characterized in that, described second is amplitude type monocycle optical grating construction with reference to grating.
22. 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:
The laser lighting light beam that sends through lighting module transmission light source module, and be radiated at alignment mark on the wafer;
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 and second imaging optical path are respectively to the alignment mark coherent 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 by first the transmitted light intensity with reference to Grating Modulation; Survey light path by second and survey alignment mark after the second imaging optical path imaging and, in the alignment mark scanning process, obtain second light signal by second the transmitted light intensity with reference to Grating Modulation;
Handle first light signal and second light signal through signal Processing and locating module, determine the positional information of alignment mark in conjunction with the phase information of the amplitude information of first light signal and second light signal.
23. 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 unit 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 mark is the multicycle optical grating construction, comprises the grating of many group different cycles;
Described alignment system comprises at least: the light source module and the lighting module that provide and transmit the multiwavelength laser illuminating bundle; Be used to gather the reflected light and the diffraction light of alignment mark, and make the image-forming module of diffraction light coherent imaging; Be used to separate the polychromatic light piece-rate system of multi-wavelength diffraction light; Be used to survey the detecting module of alignment mark picture through the light signal of reference Grating Modulation; Signal Processing and the locating module handling light signal and determine the alignment mark positional information in conjunction with the amplitude and the phase information of light signal; Wherein, the amplitude information of described light signal from the multicycle grating of forming alignment mark many groups grating coherent imaging after the amplitude type multicycle obtain with reference to the transmitted light intensity of Grating Modulation; One group of grating coherent imaging of phase information cycle minimum from the multicycle grating of forming alignment mark after the amplitude type monocycle obtain with reference to the transmitted light intensity of Grating Modulation.
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| CN112015060B (en) * | 2019-05-30 | 2021-10-19 | 上海微电子装备（集团）股份有限公司 | Phase modulation method, phase modulator, mark alignment system and readable storage medium |
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| CN113777896B (en) * | 2020-06-09 | 2023-02-28 | 上海微电子装备（集团）股份有限公司 | Alignment device, alignment method thereof and photoetching machine |
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