CN103365122B - Self-reference for lithographic equipment interferes alignment system - Google Patents

Abstract

The present invention discloses a kind of self-reference for lithographic equipment and interferes alignment system, it is characterized in that, comprising: a laser light source module, for providing illuminating bundle; One optical module, for being marked by this illuminating bundle, forms a diffraction optics signal; One signal acquisition module, for being processed by this optical signalling, obtains light intensity signal; One processing module, for processing this light intensity signal, and in conjunction with work stage position data, obtains aligned position; This optical module comprises the first optical channel and the second optical channel, and the optical signalling in this second optical channel is after treatment for eliminating the optical noise in this first optical channel.

Description

Self-reference for lithographic equipment interferes alignment system

Technical field

The present invention relates to a kind of integrated circuit equipment manufacturing field, particularly relate to a kind of self-reference for lithographic equipment and interfere alignment system.

Background technology

In semiconducter IC ic manufacturing process, complete chip needs just can complete through repeatedly photolithographic exposure usually.Except first time photoetching, the figure of this level and former level all will be exposed the figure stayed and accurately locate by the photoetching of all the other levels before exposure, have correct relative position, i.e. alignment precision between each layer pattern of such guarantee.Under normal circumstances, alignment precision is 1/3 ~ 1/5 of litho machine resolution index, and for the litho machine of 100 nanometers, alignment precision index request is less than 35nm.Alignment precision is one of the key technical indexes of projection mask aligner, and the alignment precision between mask and wafer is the key factor affecting alignment precision.When characteristic dimension CD requires less, the requirement of alignment precision and the requirement of consequent alignment precision are become more strict, as the alignment precision of the CD dimensional requirement 10nm or less of 90nm.

Between mask and wafer to the mode that mask (coaxially) aligning+silicon chip (from axle) will definitely be adopted to aim at, be namely labeled as bridge with work stage datum plate, set up mask mark with silicon chip mark between position relationship, as shown in Figure 1.The basic process of aiming at is: first by coaxial alignment system 9 (i.e. mask alignment system), realize mask mark 3 and mark aiming between 7 with the datum plate on sports platform 5, then off-axis alignment system 10 (silicon chip alignment system) is utilized, complete silicon chip alignment mark 6 and mark aiming at (being realized by twice aligning) between 7 with work stage datum plate, and then indirectly realize aiming between silicon chip alignment mark 6 with mask alignment mark 3, set up position coordinates relation therebetween.

Patent EP1148390, US00US7564534 and CN03133004.5 give a kind of self-reference and interfere alignment system, as shown in Figure 2.This alignment system is by picture whirligig 22, realize the division of alignment mark point diffraction wave surface, and division after two corrugateds relative to 180 ° rotate overlying interference, then light intensity signal detector 27 is utilized, registration signal after the detection of pupil plane place is interfered, determines the aligned position of mark 24 by signal analyzer 28.This alignment system requires that alignment mark is 180 ° of Rotational Symmetries.The most crucial devices of this alignment system as whirligig 22, for division and the rotation of marker image.

In the invention, owing to being irradiated to the fluctuation (energy variation in time of the light intensity on mark, the energy hunting caused primarily of the fluctuation of laser instrument output intensity, phase-modulation and intensity modulation and the stability of light path, environmental fluctuating cause), this fluctuation, by directly affecting the quality of signal, causes alignment error.The fluctuation of usual 1% can cause the alignment error of 0.5nm.In the present invention, the light-intensity variation of this non-useful signal is referred to as optical noise.

Prior art needs a kind of light-intensity variation (i.e. optical noise) self-reference be irradiated on mark of can effectively eliminating to interfere alignment system, improves registration signal quality.

Summary of the invention

In order to overcome the defect existed in prior art, the invention provides a kind of light-intensity variation (i.e. optical noise) self-reference be irradiated on mark of can effectively eliminating and interfering alignment system, to improve registration signal quality.

In order to realize foregoing invention object, the present invention discloses a kind of self-reference for lithographic equipment and interferes alignment system, it is characterized in that, comprising: a laser light source module, for providing illuminating bundle; One optical module, for being marked by this illuminating bundle, forms a diffraction optics signal; One signal acquisition module, for being processed by this optical signalling, obtains light intensity signal; One processing module, for processing this light intensity signal, and in conjunction with work stage position data, obtains aligned position; This optical module comprises the first optical channel and the second optical channel, and the optical signalling in this second optical channel is after treatment for eliminating the optical noise in this first optical channel.

Further, this optical noise is the optical noise comprised in any order of diffraction time, or the optical noise comprised in the combination optical signal of different diffraction level time, or the optical noise that the optical signalling that all diffracted beam is combined into comprises.

Further, this optical module also comprises illumination path and multi-wavelength branching unit, and this illuminating bundle passes through this illumination path, the first optical channel, the second optical channel and multi-wavelength branching unit successively.This illumination path comprises lighting unit, the first polarization beam apparatus, 1/4 zone plate and front group of lens.Group lens, 1/4 zone plate, the first polarization beam apparatus, light intensity beam splitter, the one 1/2 zone plate, Self-referencing interferometer, the 2 1/2 zone plate, the second polarization beam apparatus, A_1 paths converge lens, A_2 paths converge lens before this first optical channel comprises.Group lens, 1/4 zone plate, the first polarization beam apparatus, light intensity beam splitter, channel B plus lens before this second optical channel comprises.This illumination path, the first optical channel, the second optical channel share this front group of lens, 1/4 zone plate, the first polarization beam apparatus.This first optical channel and the second optical channel share this light intensity beam splitter, light intensity beam splitter by most energy distribution to the first optical channel.This multi-wavelength branching unit comprises input optical fibre, multi-wavelength shunt and output optical fibre, for by optical signal transmission to signal acquisition module.

Further, this laser light source module comprises the first laser control cabinet, and second laser controls cabinet and multi-wavelength multiplex device.This first laser control cabinet provides two visible illumination light beams, and this second laser controls cabinet and provides two infrared illumination light beams, and this visible illumination light beam carries out phase-modulation, and this infrared illumination light beam does not carry out phase-modulation.This multi-wavelength multiplex device by 4 bundle different wave lengths laser beam be combined into a branch of coaxial laser light beam, then by Optical Fiber Transmission to optical module.

Further, this signal acquisition module comprises opto-electronic conversion, demodulation, filtering and A/D modular converter, in order to obtain original light intensity signal, and is transferred to processing module.Optical noise in this first optical channel of this elimination is the optical noise that employing normalization eliminates in the first optical channel, specifically comprises following formula:

$I_{A\_1}\_\mathrm{normalised}=\frac{I_{A\_1}-{\mathrm{DC}}_{A\_1}}{I_B-{\mathrm{DC}}_B}=\frac{\mathrm{\α}}{\mathrm{\γ}}(1+\cos (\frac{4\mathrm{m\π}}{P}\mathrm{vt}-x_0))$

$I_{A\_2}\_\mathrm{normalised}=\frac{I_{A\_2}-{\mathrm{DC}}_{A\_2}}{I_B-{\mathrm{DC}}_B}=\frac{\mathrm{\β}}{\mathrm{\γ}}(1-\cos (\frac{4\mathrm{m\π}}{P}\mathrm{vt}-x_0))$

In formula, v is for aiming at uniform speed scanning speed, and t is sweep time, x ₀for mark initial position, I _totalfor the total light intensity of point diffraction wave surface, α, β and γ are respectively A_1 passage, A_2 passage and channel B light intensity scale-up factor, DC _{a_1}, DC _{a_2}and DC _bbe respectively the dark current of A_1 passage, A_2 passage and channel B, P is the cycle of mark, and m is the level time of diffraction.The optical noise that this normalization is eliminated in the first optical channel realizes in software or firmware, to obtain the light intensity signal after normalization.Light intensity signal after this normalization carries out matching in conjunction with work stage position data, solves aligned position.This aligned position adopts the normalization light intensity signal of arbitrary wavelength of A_1 passage and the arbitrary passage of A_2 passage, or adopts their various combinations.

Innovative point of the present invention is: the self-reference that The present invention gives a kind of improvement interferes alignment system structure, the second optical channel based on alignment system obtains optical signalling, the optics that first optical channel obtains is normalized, thus eliminate the alignment error being irradiated to the light-intensity variation on mark and bringing, improve the quality of registration signal, reduce alignment error.

Accompanying drawing explanation

Can be further understood by following detailed Description Of The Invention and institute's accompanying drawings about the advantages and spirit of the present invention.

Fig. 1 is the aligning schematic flow sheet from axle coaxial alignment system for lithographic equipment in prior art;

Fig. 2 is that the self-reference used in prior art interferes alignment system;

Fig. 3 is the structural representation that self-reference involved in the present invention interferes alignment system;

Fig. 4 is the schematic diagram of the original aligning light intensity signal obtained in the first optical channel;

Fig. 5 is the schematic diagram of the normalization light intensity signal obtained in the second optical channel;

Fig. 6 is the schematic diagram of the registration signal after normalized.

Embodiment

Below, describe in detail by reference to the accompanying drawings according to a preferred embodiment of the invention.For convenience of description and highlight the present invention, in accompanying drawing, eliminate existing associated components in prior art, and the description to these well-known components will be omitted.

The object of the invention is that the self-reference providing a kind of improvement interferes alignment system, this alignment system effectively can eliminate the signal quality variation that the light-intensity variation (i.e. optical noise) be irradiated on mark causes, obtain better registration signal, and then the repeatable accuracy of aligning can be improved.

As shown in Figure 3, the alignment system that the present invention gives comprises laser light source module 400, optical module 300, electron collection module 500, software module 600.Wherein, laser light source module 400 is for providing required illuminating bundle.Optical module 300, for the light beam from mark diffraction is carried out optical processing, forms optical signalling.Electron collection module 500 is for the treatment of optical signalling, and obtain light intensity signal, this signal is also referred to as original light intensity signal.Software module 600 for the treatment of light intensity signal, and obtains normalization light intensity signal after normalization, then in conjunction with work stage position data, through process of fitting treatment, obtain a series of peaks of light intensity signal, and determine the position of mark further, this position is aligned position.Realization of the present invention needs the position data of synchronous acquisition work stage, not shown in figure 3, but do not affect the understanding of the present invention and realization, specifically can with reference at first patent CN200810033263.7, CN200710045495.X, CN200710044153.6, CN200710044152.1, CN200810035115.9, CN200810040234.3, CN200910052799.8, CN200910047030.7, CN200910194853.2,200910055927.4.

Laser light source module 400 comprises the first laser control cabinet 402, second laser controls cabinet 403 and multi-wavelength multiplex device 401.Wherein the first laser control cabinet 402 provides the laser beam of 2 visible wavelengths, and as the laser beam of 532nm and 633nm, second laser controls the laser beam that cabinet 403 provides 2 infrared wavelengths, as the laser beam of 780nm and 850nm.Wherein, visible illumination light beam need carry out phase-modulation, and to suppress parasitic interaction, and two infrared illumination light beams do not carry out phase-modulation.The laser beam of each wavelength is all transferred to multi-wavelength multiplex device 401 by a single-mode polarization maintaining fiber.Multi-wavelength multiplex device 401 by 4 bundle different wave lengths laser beam be combined into a branch of coaxial laser beam, then by Optical Fiber Transmission to optical module.This coaxial degree will affect alignment precision.After closing bundle, laser beam is transferred to optical module 300.

Optical module 300 comprises illumination path, the first optical channel, the second optical channel and multi-wavelength branching unit.Illumination path comprises lighting unit 306, first polarization beam apparatus 304,1/4 zone plate 305 and front group of lens 311.Illumination path is used for illuminating bundle being imported to silicon chip mark, work stage mark or work stage datum plate mark.Group lens 311,1/4 zone plate 305, first polarization beam apparatus 304, light intensity beam splitter the 303, the 1 zone plate 302, Self-referencing interferometer the 301, the 2 1/2 zone plate 308, second polarization beam apparatus 309, A_1 paths converge lens 312, A_2 paths converge lens 313 before first optical channel comprises.First optical channel comprises for optical signalling is imported to multi-wavelength branching unit.Group lens 311,1/4 zone plate 305, first polarization beam apparatus 304, light intensity beam splitter 303, channel B plus lens 314 before second optical channel comprises.Second optical channel is used for optical signalling to import to multi-wavelength branching unit.Group lens 311,1/4 zone plate 305, first polarization beam apparatus 304 before illumination path, the first optical channel, the second optical channel share.First optical channel and the second optical channel share light intensity beam splitter 303.Multi-wavelength branching unit comprises input optical fibre, multi-wavelength shunt 307 and output optical fibre, for optical signalling is imported electron collection module 500.

Close the laser beam after bundle successively by after each assembly of illumination path, vertical irradiation is on mark, and produce diffracted beam (also can be referred to as point diffraction wave surface), this point diffraction wave surface carries the positional information of mark.Point diffraction wave surface is successively by front group of lens 311,1/4 zone plate 305, first polarization beam apparatus 304 and light intensity beam splitter 303.After light intensity beam splitter 303, point diffraction wave surface by beam splitting in two optical channels: the first optical channel and the second optical channel, the energy Ratios of beam splitting can adjust as required.Because the optical signalling of the second optical channel is for eliminating the optical noise in the first optical channel, only need to take fraction energy.During design, most of energy consideration by beam splitting in the first optical channel.Such as, the first optical channel can be designed and the second optical channel beam splitting energy Ratios is designed to 9:1 etc.In the present invention, come from optical signalling in the second optical channel after subsequent module for processing for eliminating the optical noise in the first optical channel.Optical noise can for comprise in arbitrary number of level time optical signalling optical noise, different diffraction level time combination optical signal in the optical noise that comprises of the optical noise, the optical signalling that all diffracted beam is combined into that comprise.Particularly, or needs can be aimed at carry out choices process according to design, in an embodiment of the present invention, only the optical noise comprised in the secondary optical signalling of a certain order of diffraction is processed, but other situations also should comprise in the present invention.

In the first optical channel, point diffraction wave surface is by after Self-referencing interferometer, aplanatic two corrugateds (corrugated 1 and corrugated 2) will be divided into, incident corrugated 1 is rotated counterclockwise 90 degree, and incident corrugated 2 dextrorotation turn 90 degrees, the two revolves turnback relatively, interferes and penetrate after overlap.Point diffraction wave surface after overlap is carried out polarization beam splitting by the second polarization beam apparatus, and beam splitting is in A_1 and A-2 light path respectively.In A_1 passage, comprise 0 grade of light and each senior light, and in A_2 passage, only comprise each senior light.A_1 paths converge lens and A_2 paths converge lens are used for this channel beam to converge in the input optical fibre of multi-wavelength branching unit.In the second optical channel, converged to by channel B plus lens equally in the input optical fibre of multi-wavelength branching unit.The multi-wavelength mixed light beam of input is carried out monochromatic beam splitting by multi-wavelength shunt, and is transferred to electron collection module by output optical fibre.Owing to being 4 wavelength illumination light beams, correspondence four is restrainted output optical fibre by a branch of input optical fibre.The optical signalling of the A_1 passage in output optical fibre, A_2 passage and each wavelength of channel B will be transferred in each electricity passage of electron collection module respectively.In addition, 1/4 zone plate 305 in optical module and each 1/2 zone plate 302,308 are for adjusting the polarization state of light beam.

Electron collection module 500 comprises the functions such as opto-electronic conversion, demodulation, filtering and A/D conversion, to obtain light intensity signal and to be transferred to software module 600.For distinguishing with follow-up light intensity signal after normalized, this place's light intensity signal is referred to as original light intensity signal.The idiographic flow of signal transacting can list of references 1 (Alignment Technology of Weak Photoelectricit Signal Detection, Yang Xingping, Cheng Jianrui, electronics industry specialized equipment, 2006,140:7 ~ 12) and at first patent CN200810035115.9, introducing here as known technology.

Normalized realizes in software or firmware, to obtain the light intensity signal after normalization.It should be noted that, light intensity signal in first optical channel solves for aligned position after eliminating optical noise, and the light intensity signal in the second optical channel is only for eliminating the optical noise in the first optical channel, the light intensity signal namely in normalization first optical channel.

In the first optical channel, the A_1 passage comprised is mutually long destructive interference with A_2 passage, and its optical signalling is respectively shown in formula one and formula two, and concrete form as shown in Figure 4

$I_{A\_1}={\mathrm{DC}}_{A\_1}+{\mathrm{\αI}}_{\mathrm{total}}(1+\cos (\frac{4\mathrm{m\π}}{P}\mathrm{vt}-x_0))$ Formula one

$I_{A\_2}={\mathrm{DC}}_{A\_2}+{\mathrm{\βI}}_{\mathrm{total}}(1-\cos (\frac{4\mathrm{m\π}}{P}\mathrm{vt}-x_0))$ Formula two

In formula, v is for aiming at uniform speed scanning speed, and t is sweep time, x ₀for mark initial position, I _totalfor the total light intensity of point diffraction wave surface, α and β is respectively the light intensity scale-up factor of A_1 passage and A_2 passage, DC _{a_1}and DC _{a_2}be respectively the dark current of A_1 passage and A_2 passage, P is the cycle of mark, and m is the level time of diffraction.

It should be noted that, in the diffracted beam of mark, when only ± 1 grade of light enters optical module, A_1 passage and A_2 channel optical signal only contain the information of this grade time; When very multi-stage light enters optical module, A_1 passage and A_2 channel optical signal are the superposition of at different levels optical signallings.By adding aperture diaphragm in the numerical aperture of front group of lens or light path, the level time that light beam enters can be controlled.Obviously be harmonic signal or rahmonic signal by the optical signalling of formula one and two, A_1 passage and A_2 passage.Due to the impact of optical noise, A_1 passage and A_2 passage are difficult to obtain desirable signal, the I namely in formula one and two _totalfor time dependent value, in the signal graph shown in Fig. 4, embody this fluctuation.

Optical signalling in channel B (i.e. the second optical channel) is for shown in formula three.

I _b=DC _b+ γ I _totalformula three

In formula, γ is the light intensity scale-up factor of this passage, DC _bfor the dark current of this passage.If without optical noise, this signal is a DC component or the DC component that there is minor fluctuations (minor fluctuations causes primarily of dark current fluctuation, and the dark current that namely electron collection modular circuit noise causes fluctuates).In time there is optical noise, this signal will be a fluctuation signal, as shown in Figure 5.Because optical noise affects A_1 passage and A_2 passage and channel B simultaneously, there is the synchronism of correlativity or time by with the light intensity signal in A_1 passage and A_2 passage in the light intensity signal in channel B.Obviously, the light intensity signal in channel B is utilized to be the fluctuation (eliminating the wave portion caused by optical noise) can eliminating light intensity signal in A_1 passage and A_2 passage.Concrete method for normalizing is:

$I_{A\_1}\_\mathrm{normalised}=\frac{I_{A\_1}-{\mathrm{DC}}_{A\_1}}{I_B-{\mathrm{DC}}_B}=\frac{\mathrm{\α}}{\mathrm{\γ}}(1+\cos (\frac{4\mathrm{m\π}}{P}\mathrm{vt}-x_0))$ Formula four

$I_{A\_2}\_\mathrm{normalised}=\frac{I_{A\_2}-{\mathrm{DC}}_{A\_2}}{I_B-{\mathrm{DC}}_B}=\frac{\mathrm{\β}}{\mathrm{\γ}}(1-\cos (\frac{4\mathrm{m\π}}{P}\mathrm{vt}-x_0))$ Formula five

By this normalization formula, variations per hour I can be eliminated _total, namely eliminate the optical noise impact in A_1 passage and A_2 passage, improve the quality of registration signal, as shown in Figure 6.In conjunction with work stage position data and signal fitting, aligned position can be obtained.Owing to adopting 4 wavelength illumination light beams, A_1 passage and A_2 passage contain 4 groups of light intensity signals (2 passage summations are 8 groups) respectively, and each group all independently can solve aligned position.Some aligned positions can be selected as final aligned position, also can comprehensive multiple aligned position, after asking for final aligned position, as the way adopting each group of aligned position average.

Solving of light intensity signal matching and aligned position, with reference to the method described in first patent CN200810033263.7, CN200710045495.X, CN200710044153.6, CN200710044152.1, CN200810035115.9, CN200810040234.3, CN200910052799.8, CN200910047030.7, CN200910194853.2,200910055927.4, can introduce as known technology herein.About the mark caught or aim at by first time scanning 16 micro meter periodic of mark, the mark of second time scanning 17.6 micro meter periodic, utilizes the immediate peak obtaining registration signal to determine the position marked.These all easily realize, and this thought and method has concrete description in first patent, introduce as known technology herein.

Just preferred embodiment of the present invention described in this instructions, above embodiment is only in order to illustrate technical scheme of the present invention but not limitation of the present invention.All those skilled in the art, all should be within the scope of the present invention under this invention's idea by the available technical scheme of logical analysis, reasoning, or a limited experiment.

Claims (16)

1. the self-reference for lithographic equipment interferes an alignment system, it is characterized in that, comprising:

One laser light source module, for providing illuminating bundle;

One optical module, for by described illuminating bundle mark, forms a diffraction optics signal;

One signal acquisition module, for being processed by described optical signalling, obtains light intensity signal;

One processing module, for processing described light intensity signal, and in conjunction with work stage position data, obtains aligned position; Described optical module comprises the first optical channel and the second optical channel, and the optical signalling in described second optical channel is after treatment for eliminating the optical noise in described first optical channel;

Group lens, 1/4 zone plate, the first polarization beam apparatus, light intensity beam splitter, the one 1/2 zone plate, Self-referencing interferometer, the 2 1/2 zone plate, the second polarization beam apparatus, A_1 paths converge lens, A_2 paths converge lens before described first optical channel comprises.

2. alignment system according to claim 1, it is characterized in that, described optical noise is the optical noise comprised in any order of diffraction time, or the optical noise comprised in the combination optical signal of different diffraction level time, or the optical noise that the optical signalling that all diffracted beam is combined into comprises.

3. alignment system according to claim 1, it is characterized in that, described optical module also comprises illumination path and multi-wavelength branching unit, and described illuminating bundle is successively through described illumination path, the first optical channel, the second optical channel and multi-wavelength branching unit.

4. alignment system according to claim 3, is characterized in that, described illumination path comprises lighting unit, the first polarization beam apparatus, 1/4 zone plate and front group of lens.

5. alignment system according to claim 3, is characterized in that, group lens, 1/4 zone plate, the first polarization beam apparatus, light intensity beam splitter, channel B plus lens before described second optical channel comprises.

6. alignment system according to claim 5, is characterized in that, described illumination path, the first optical channel, the second optical channel share described front group lens, 1/4 zone plate, the first polarization beam apparatus.

7. alignment system according to claim 5, is characterized in that, described first optical channel and the second optical channel share described light intensity beam splitter, light intensity beam splitter by most energy distribution to the first optical channel.

8. alignment system according to claim 3, is characterized in that, described multi-wavelength branching unit comprises input optical fibre, multi-wavelength shunt and output optical fibre, for by optical signal transmission to signal acquisition module.

9. alignment system according to claim 1, is characterized in that, described laser light source module comprises the first laser control cabinet, and second laser controls cabinet and multi-wavelength multiplex device.

10. alignment system according to claim 9, it is characterized in that, described first laser control cabinet provides two visible illumination light beams, described second laser controls cabinet and provides two infrared illumination light beams, described visible illumination light beam carries out phase-modulation, and described infrared illumination light beam does not carry out phase-modulation.

11. alignment systems according to claim 9, is characterized in that, described multi-wavelength multiplex device by 4 bundle different wave lengths laser beam be combined into a branch of coaxial laser light beam, then by Optical Fiber Transmission to optical module.

12. alignment systems according to claim 1, is characterized in that, described signal acquisition module comprises opto-electronic conversion, demodulation, filtering and A/D modular converter, in order to obtain original light intensity signal, and are transferred to described processing module.

13. alignment systems according to claim 1, is characterized in that, the optical noise in described first optical channel of described elimination is the optical noise that employing normalization eliminates in the first optical channel, specifically comprises following formula:

$I_{A\_1}\_normalised=\frac{I_{A\_1}-{\mathrm{DC}}_{A\_1}}{I_B-{\mathrm{DC}}_B}=\frac{\mathrm{\α}}{\mathrm{\γ}}(1+cos(\frac{4m\mathrm{\π}}{P}vt-x_0))$

$I_{A\_2}\_normalised=\frac{I_{A\_2}-{\mathrm{DC}}_{A\_2}}{I_B-{\mathrm{DC}}_B}=\frac{\mathrm{\β}}{\mathrm{\γ}}(1-cos(\frac{4m\mathrm{\π}}{P}vt-x_0))$

In formula, v is for aiming at uniform speed scanning speed, and t is sweep time, x ₀for mark initial position, α, β and γ are respectively A_1 passage, A_2 passage and channel B light intensity scale-up factor, DC _{a_1}, DC _{a_2}and DC _bbe respectively the dark current of A_1 passage, A_2 passage and channel B, P is the cycle of mark, and m is the level time of diffraction, I _{a_1}, I _{a_2}, I _bbe respectively the optical signalling in A_1 passage, A_2 passage and channel B.

14. alignment systems according to claim 13, is characterized in that, the optical noise that described normalization is eliminated in the first optical channel realizes in software or firmware, to obtain the light intensity signal after normalization.

15. alignment systems according to claim 14, is characterized in that, the light intensity signal after described normalization carries out matching in conjunction with work stage position data, solves aligned position.

16. alignment systems according to claim 15, is characterized in that, described aligned position adopts the normalization light intensity signal of arbitrary wavelength of A_1 passage and the arbitrary passage of A_2 passage, or adopts their various combinations.