CN104807398B - A kind of method and apparatus in OCD measurements for screening wave band - Google Patents

Abstract

The method for screening wave band is used in OCD measurements the present invention provides a kind of, wherein, this method comprises the following steps：a）For each structural parameters in multiple structural parameters of structural model to be measured, the spectral signal offset of corresponding spectrally each wavelength points is caused according to being changed by the structural parameters, determines sensitivity of the structural parameters at each wavelength points；b）According to the sensitivity at each of which wavelength points respectively of the multiple structural parameters, one or more spectral bands are screened；C) according to the spectral band filtered out, measure spectrum and the matching of theoretical spectral database are realized.According to the method for the present embodiment, the signal-to-noise ratio and accuracy of OCD parameter measurements can be improved.

Description

A kind of method and apparatus in OCD measurements for screening wave band

Technical field

The present invention relates to field of optical measuring technologies more particularly to one kind in optical critical dimension OCD（Optical Critical Dimension）Method and apparatus in measurement technology for screening wave band.

Background technology

As mole epoch close on after 2x nm technology nodes, the structure size of device is less and less, new processing procedure and new Material introduces unique geometry rule and measurement request, such as three-dimensional flash memory 3D（3-Dimensional）Flash、 Fin FET FinFET（Fin-Field-Effect-Transistor）, immersion type photolithography, optical near-correction OPC（Optical Proximity Correction）, measurement DBM based on design（Design Based Metrology）、 Dual mask DP（Double Patterning）, strained-channel and chip stack through hole technology TSV（Through Silicon Via）Wait the importing of 3D devices and new technology, driving optical critical dimension OCD（Optical Critical Dimension）It surveys Amount technology further promotes measurement accuracy and stability, less and less to tackle further fine technology controlling and process demand and size Device architecture measurement request.

And in the setting of the existing optical critical dimension OCD measuring apparatus based on scattering spectrum signal, it is usually used The light source of broadband spectral.Thus it is used for the parameter setting for calculating the simulation software of theoretical spectrum and obtained theoretical spectral and survey In the fitting and evaluation of measuring spectrum, the total data of corresponding broadband spectral is generally also used.Although such method is to improving Signal-to-noise ratio is helpful, but one of possible deficiency is that have to reflect poor sensitivity of the structural parameters to be measured on wavelength dimension comprehensively It is different, it is unfavorable for improving the signal-to-noise ratio and the accuracy of stability and measurement result of OCD measurements, it is therefore necessary to which invention is a kind of The method and apparatus of the screening wave band of new each wavelength of consideration comprehensively (section) sensitivity factor.

The content of the invention

The object of the present invention is to provide a kind of method and apparatus for being used to screen wave band in OCD measurements and one kind really Surely the method and apparatus of coefficient of the one or more spectral bands filtered out in spectrum simulation.

According to an aspect of the present invention, provide it is a kind of in OCD measurements for the method for screening wave band, wherein, the party Method comprises the following steps：

A is for each structural parameters in multiple structural parameters of structural model to be measured, according to the change by the structural parameters Change and caused by corresponding spectrally each wavelength points spectral signal offset, determine the structural parameters in each wavelength points The sensitivity at place；

B screens one or more spectrum according to the sensitivity at each of which wavelength points respectively of the multiple structural parameters Wave band.

According to another aspect of the present invention, a kind of one or more spectral bands for determining to filter out are provided in spectrum The method of coefficient during fitting, wherein, this method includes each spectrum in one or more spectral bands to filtering out Wave band performs following steps：

I）It is at each wavelength points of the spectral band respectively, not normalized sensitive according to the multiple structural parameters Degree, obtains not normalized sensitivity of each structural parameters in the spectral band in the multiple structural parameters；

II）Systemization processing is carried out to not normalized sensitivity of the multiple structural parameters in the spectral band, really Sensitivity after the systemization of the fixed spectral band；

III）According to the sensitivity after the systemization of the spectral band and the sensitivity after full wave systemization, the light is determined The ratio of sensitivity and the sensitivity after full wave systemization after the systemization of wave band is composed, and the light is determined according to the ratio Compose coefficient of the wave band in spectrum simulation.

According to another aspect of the present invention, a kind of wave band screening for being used to screen wave band in OCD measurements is additionally provided Device, wherein, which includes following device：

First determining device, for each structural parameters in multiple structural parameters for structural model to be measured, according to The spectral signal offset of corresponding spectrally each wavelength points, determines the structural parameters caused by as the variation of the structural parameters Sensitivity at each wavelength points；

Screening plant, for according to the sensitivity at each of which wavelength points respectively of the multiple structural parameters, screening one A or multiple spectral bands.

According to another aspect of the present invention, a kind of one or more spectral bands for determining to filter out are provided in spectrum The wave band screening plant of coefficient during fitting, wherein, which further includes one or more spectrum to filtering out Each spectral band in wave band performs the following steps of operation：

Second acquisition device, for according to the multiple structural parameters respectively at each wavelength points of the spectral band , not normalized sensitivity, obtain non-normalizing of each structural parameters in the spectral band in the multiple structural parameters The sensitivity of change；

3rd determining device, for each structural parameters not returning in the spectral band in the multiple structural parameters One sensitivity changed carries out systemization processing, determines the sensitivity after the systemization of the spectral band；

4th determining device, for the sensitivity after the systemization according to the spectral band and the spirit after full wave systemization Sensitivity determines the ratio of the sensitivity after the systemization of the spectral band and the sensitivity after full wave systemization, and according to described Ratio determines coefficient of the spectral band in spectrum simulation.

Compared with prior art, the present invention has the following advantages：1）It, can be by treating geodesic structure under given measurement pattern The sensitivity analysis of each structural parameters of model, and the system weight of each structural parameters is combined, meet screening rule to screen One or more then has the spectral band of different sensitivity feature, enabling integrated structure parameter is in technology controlling and process Importance and user's attention rate carry out the sensitivity analysis of structural parameters, so as to towards given processing step to be monitored Or device under test structure measurement task when, it can be achieved that consider multiple structural parameters to be measured collaborations, promoted in fitting is evaluated The flexibility of wavelength dimension；2）The system weight of each structural parameters can be combined, to determine the one or more spectrum filtered out The ratio between the sensitivity after sensitivity and full wave systemization after the systemization of wave band, so that it is determined that the one or more light Compose coefficient of the wave band when carrying out spectrum simulation so that can to coefficient of the different wavelength regions when participating in fitting and evaluating into Row is targetedly set, so as to significantly improve the Stability and veracity of OCD measurement results；Also, theoretical spectral with In the fit procedure of measure spectrum, consider degree of concern of the user to different structural parameters to be measured in device architecture, be based on The weight of wavelength sensitivity distribution is set, and can improve the accuracy of the match value of structural parameters to be measured.Therefore, towards set to be measured Device architecture considers multiple structural parameters collaborations to be measured flexibly and targetedly fitting weight is set in wavelength dimension progress It puts, has realistic meaning.

Description of the drawings

By reading the detailed description made to non-limiting example made with reference to the following drawings, of the invention is other Feature, objects and advantages will become more apparent upon：

Fig. 1 is illustrating in OCD measurements for screening the flow of the method for wave band for a preferred embodiment of the present invention Figure；

Fig. 2 is that the flow of the method in OCD measurements for screening wave band of another preferred embodiment of the present invention is shown It is intended to；

Fig. 3 is the wave band screening plant for being used to screen wave band in OCD measurements of a preferred embodiment of the present invention Structure diagram；

Fig. 4 is the wave band screening plant for being used to screen wave band in OCD measurements of another preferred embodiment of the present invention Structure diagram；

Fig. 5 is the flow diagram that OCD measurements are carried out based on OCD measuring principles；

Fig. 6 is polysilicon structural model schematic diagram to be measured；

Fig. 7 is the sensitivity of three kinds of structural parameters of the structural model to be measured shown in Fig. 6 with the distribution schematic diagram of wavelength；

Fig. 8 is point of the sensitivity after the normalization of three kinds of structural parameters of the structural model to be measured shown in Fig. 6 with wavelength Cloth schematic diagram；

Fig. 9 is to take w₁=w₂=w₃The total sensitivity of three kinds of structural parameters of the structural model to be measured when=1 shown in Fig. 6 is with wavelength Distribution schematic diagram；

Figure 10 is to take w₁=20, w₂=2, w₃The total sensitivity of three kinds of structural parameters of the structural model to be measured when=2 shown in Fig. 6 With the distribution schematic diagram of wavelength.

The same or similar reference numeral represents the same or similar component in attached drawing.

Specific embodiment

To be illustrated more clearly that the solution of the present invention, below first to it is a kind of based on the OCD measuring principles of optical scattering light into Row explanation：

The realization step of OCD measuring principles may include：

1）OCD measuring apparatus establishes the corresponding theoretical spectral database of pattern with treating geodesic structure.

The specific implementation of the step includes：First, OCD measuring apparatus is according to the pattern and technological process for treating geodesic structure Establish structural model to be measured；Then, OCD measuring apparatus sets one group of parameter for describing the model to carry out the structural model to be measured Theoretical simulation, to obtain the theoretical spectral for treating the given parameter of this corresponding group of geodesic structure；Then, OCD measuring apparatus is according to emulation The series of theories spectrum for treating geodesic structure obtained, to establish the corresponding theoretical spectral database for treating geodesic structure.

Wherein, structural model to be measured can be determined by its structural parameters variable, and one is treated that geodesic structure has multiple knots Structure parametric variable.Usually, available parameter vector x=(x₀,x₁,...,x_L-1)^T, x_j, j=0 ..., L-1, to represent to treat geodesic structure Whole structural parameters, structural model to be measured as shown in Figure 6 include structural parameters CD, SWA, t_poly, t_oxide, then may be used With parameter vector x=(CD, SWA, t_poly, t_oxide)^TTo describe the structural model to be measured.Join for given concrete structure Array closes x, according to the light scattering principle of periodic structure, can calculate the structural model to be measured that concrete structure parameter determines and correspond to The theoretical spectral s (λ) for treating geodesic structure.The combination of Different structural parameters is assigned, different theoretical spectrals can be generated, so as to root The theoretical spectral database of geodesic structure is treated according to such different theoretical spectral foundation.

It, can be according to rigorous couple-wave analysis RCWA as an example（Rigorous Coupled-Wave Analysis） To obtain the theoretical spectral data for treating geodesic structure.

It should be appreciated by those skilled in the art that above-mentioned treat the theoretical spectral data of geodesic structure using RCWA methods to obtain Mode is only for example, any other calculates the method for theoretical spectroscopic data, such as using the method for the present invention, should be included in this Within the protection domain of invention, and it is incorporated herein by reference.

2）OCD measuring apparatus obtains the measure spectrum for treating geodesic structure.

Specifically, OCD measuring apparatus obtains the scattered signal for including the structural information for treating geodesic structure, and is dissipated what is received It is the measure spectrum for including the structural information for treating geodesic structure to penetrate signal processing.Wherein, the description form bag of the numerical value of measure spectrum It includes but is not limited to：Reflectivity R_s,R_p, the description tan ψ and cos Δ of polarization state variation, Polarization fourier coefficient α, β, The directly Muller matrix of output description scattering process（Mueller Matrix）, NCS spectral patterns etc.；Wherein, NCS spectral patterns represent difference Corresponding three polarization spectrums for being referred to as N, C, S, N, C, S are the element of stoke vectors respectively, in Muller matrix spectrum types In, stoke vectors are a kind of modes for representing emergent light and incident light.

3）The characteristic spectrum with measure spectrum best match is found from theoretical spectral database, so that it is determined that the knot to be measured The structural parameters of structure.

Specifically, OCD measuring apparatus is according to predetermined matching standard, by step 1）The theoretical spectral for treating geodesic structure of middle foundation Database and step 2）The measure spectrum for treating geodesic structure of middle acquisition is matched, come obtain it is in theoretical spectral database, with The characteristic spectrum of measure spectrum best match, and the parameter vector according to corresponding to this feature spectrum, Come when determining best match this treat the structural parameters of geodesic structure, wherein, x_j, j=0 ..., L-1, to represent to treat that geodesic structure is whole Structural parameters.That is, parameter vectorCorresponding theoretical spectral s (x^*, λ) and measure spectrum s_M(λ) Best match can be achieved.Preferably, the predetermined matching standard may be employed goodness of fit GOF (Goodness of Fit) or Root-mean-square error RMSE (Root Mean Square Error) etc..

Fig. 5 is the flow diagram that OCD measurements are carried out according to above-mentioned OCD measuring principles.

During the structural parameters for treating geodesic structure carry out sensitivity analysis, sensitivity formula is defined as follows：

Wherein, Parameter be some structural parameters nominal value numerical value, also can symbol turn to x_j；Δ Parameter is The variable quantity that the corresponding structural parameters introduce, i.e. Δ x_j, therefore have：

Signal is signal value of certain type spectrum in some wavelength band；Δ Signal is structural parameters x_jIn the ripple The overall signal offset of segment limit, can be by structural parameters x_jFloat value Δ x_jCaused by selected all wavelength points Spectral signal offset carries out statistical disposition to obtain.

Meanwhile define Δ S (x, Δ x_j,λ_i) represent structural parameters x_jIn certain wavelength points λ_i, the spectrum at (i=1 ..., N) Signal offset.Such as following formula：

ΔS(x,Δx_j,λ_i)=s(x,Δx_j,λi)-s(x,0,λ_i)

Wherein, s (x, Δ x_j,λ_i) represent structural parameters x_jBased on its nominal value floating Δ x_jWhen in wavelength points λ_iWhat place generated Spectroscopic data, meanwhile, remaining structural parameters takes respective nominal values；s(x,0,λ_i) represent structural parameters x_jFor its nominal value when in ripple Long point λ_iLocate the spectroscopic data generated, be that all structural parameters take its nominal value.

In general, Δ Signal take root-mean-square error calculation to it is selected measurement wave band spectrum change value at Reason, the wavelength that wave band selected by N expressions is included are counted out, λ_i, (i=1 ..., N), with reference to Δ S (x, Δ x_j,λ_i) definition, There is following formula,

Correspondingly, to some structural parameters x to be measured at each wavelength points_jSensitivityIt can be defined as follows：

Normalization sensitivity of the single structural parameters to be measured at each wavelength pointsIt can be defined as follows：

The present invention is described in further detail below in conjunction with the accompanying drawings.

Fig. 1 is illustrating in OCD measurements for screening the flow of the method for wave band for a preferred embodiment of the present invention Figure, wherein, the screening wave band refers to sub-band of the screening with different sensitivity feature；The present invention for screening wave band The step of structural parameters for treating geodesic structure that method relates generally to shown in Fig. 5 carry out sensitivity analysis.

Wherein, the method for the present embodiment is mainly realized by computer equipment.Preferably, meter according to the present invention Calculating machine equipment includes OCD measuring apparatus.

It should be noted that the OCD measuring apparatus is only for example, the other existing or computer that is likely to occur from now on Equipment is such as applicable to the present invention, should also be included within the scope of the present invention, and is incorporated herein by reference.

Step S1 and step S2 is included according to the method for the present embodiment.

In step sl, for each structural parameters in multiple structural parameters of structural model to be measured, computer equipment The spectral signal offset of corresponding spectrally each wavelength points, determines the structure caused by according to the variation as the structural parameters Sensitivity of the parameter at each wavelength points；Wherein, as the variation of structural parameters and caused by corresponding spectrally each ripple The spectral signal offset of long point can be the theory of nominal value and neighbor that structural parameters are calculated beforehand through certain mode Difference between spectroscopic data is obtained, be then provided to computer equipment or is calculated by computer equipment , should be calculated as computer equipment as the variation of structural parameters and caused by corresponding spectrally each wavelength points spectral signal it is inclined The specific method of shifting amount will be described in detail in following embodiment.Then pass through step S1, it may be determined that each in multiple structural parameters Sensitivity of the structural parameters at each wavelength points.Wherein, the variation of said structure parameter is often small.

Wherein, the structural model to be measured is the simulation model for treating geodesic structure, for that can represent to treat the material of geodesic structure And the model of structural information；Wherein, the structural parameters can be for representing each of the structure feature of the structural model to be measured Kind parameter, such as the critical size CD of structural model to be measured（Critical Dimension）, film thickness（thickness）、 Sidewall angles SWA（Side Wall Angle）With height HT, trapezoidal footing and tip circle etc..

For example, Fig. 6 is the structural model schematic diagram to be measured of gained after polysilicon structure simulation to be measured, the structural model to be measured It can represent that polysilicon treats the material and structural information of geodesic structure.It will be appreciated from fig. 6 that this treats the material of geodesic structure from the bottom up successively For：Silicon, silica, polysilicon；This treats that the structural parameters of geodesic structure include：Critical size CD, Sidewall angles SWA, polysilicon Gate height HT etc..

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that it is any for representing the various parameters of the structure feature of the structural model to be measured, It should be included in as defined in the range of the structural parameters of the present invention.

Preferably for each structural parameters in multiple structural parameters of structural model to be measured, computer equipment can root The spectral signal offset of corresponding spectrally each wavelength points caused by according to the variation as the structural parameters, and in selected wave band Sensitivity of the structural parameters at each wavelength points is determined based on the sensitivity formula.

For example, for the structural model to be measured shown in Fig. 6, the structural parameters of the structural model to be measured include：Critical size CD, Sidewall angles SWA, gate height HT.Computer equipment can calculate structural parameters CD, SWA, HT respectively according to the following formula and exist Wavelength points λ_iThe sensitivity at place：

Wherein, x is parameter vector, represents each structural parameters involved by structural model to be measured（In this example, by structure Parameter CD, SWA and HT describe to treat the profile of geodesic structure, then x=[CD, SWA, HT] expressions are made of CD, SWA and HT structure Parameter vector）.Represent structural parameters x_jIn wavelength points λ_iThe sensitivity at place, x_jRepresent that some that investigation is waited in x is tied Structure parameter, Δ x_jRepresent structural parameters x_jFloat value near its nominal value, Δ S (x, Δ x_j,λ_i) represent structural parameters x_j Certain wavelength points λ_iSpectral signal offset at (i=1 ..., N), the wavelength that wave band selected by N expressions is included are counted out.It will be real Involved specific structural parameters name code to be measured replaces Δ x in example_j, there is following formula：

Wherein, SSt_CD(λ i), SSt_SWA(λ i) and SSt_HT(λ i) represents structural parameters CD, SWA and HT in wavelength points λ respectively_i The sensitivity at place.Fig. 7 is that the sensitivity of three kinds of structural parameters of the structural model to be measured shown in Fig. 6 is illustrated with the distribution of wavelength Scheme, three curves in figure are respectively the sensitivity of structural parameters CD, SWA, HT of the structural model to be measured shown in Fig. 6 with wavelength Distribution curve, wherein, transverse axis represent wavelength, the longitudinal axis represent sensitivity.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that each structural parameters in any multiple structural parameters for structural model to be measured, The spectral signal offset of corresponding spectrally each wavelength points, determines the structure caused by according to the variation as the structural parameters The realization method of sensitivity of the parameter at each wavelength points, should be included in the scope of the present invention.

In step s 2, computer equipment according to multiple structural parameters of structural model to be measured respectively in each of which wavelength points One or more spectral bands are screened in the sensitivity at place.

Specifically, various ways can be used according to the multiple structural parameters respectively in each of which wavelength points in computer equipment One or more spectral bands are screened in the sensitivity at place.

For example, being manually respectively provided with a threshold of sensitivity to each structural parameters in multiple structural parameters, computer is set It is standby that such threshold of sensitivity and is combined according to the sensitivity at each of which wavelength points respectively of the multiple structural parameters, directly Filter out one or more spectral bands；At each wavelength points in the one or more spectral bands filtered out, each The sensitivity of structural parameters is above the corresponding threshold of sensitivity of the structural parameters.

In another example a unified threshold of sensitivity is manually set.Before spectral band is screened, computer equipment is to more Each sensitivity of the structural parameters at each wavelength points is normalized in a structural parameters, and according to normalized Rear sensitivity and the unified threshold of sensitivity screen one or more spectral bands；Wherein, the one or more quilt At each wavelength points in the spectral band filtered out, the sensitivity of each structural parameters is above the unified threshold of sensitivity Value.

As a kind of preferred embodiment of step S2, step S2 includes step S21 and step S22.

In the step s 21, computer equipment is sensitive at each of which wavelength points respectively according to the multiple structural parameters Degree carries out the sensitivity of all structural parameters at each wavelength points systemization processing, after obtaining the system at each wavelength points Total sensitivity.

Wherein, systemization processing is carried out to the sensitivity of all structural parameters at a wavelength points, is represented the wavelength The corresponding multiple sensitivity processing of all structural parameters at point are corresponding with the wavelength points, can reflect all structures One sensitivity of the overall sensitivity of parameter；For example, to all structural parameters HT, CD at wavelength points 390 shown in Fig. 8 and Corresponding three sensitivity of SWA carry out systemization processing, can obtain it is at wavelength points 390 shown in Fig. 9, can reflect One sensitivity of the overall sensitivity of structural parameters HT, CD and SWA.

Specifically, computer equipment is right according to the sensitivity at each of which wavelength points respectively of the multiple structural parameters The sensitivity of all structural parameters at each wavelength points carries out systemization processing, obtains total spirit after the systemization at each wavelength points The realization method of sensitivity includes but not limited to：

1）Computer equipment is drawn multiple according to the sensitivity at each of which wavelength points respectively of the multiple structural parameters The sensitivity curve of each structural parameters in structural parameters is merged by curve to all structural parameters at each wavelength points Sensitivity carries out systemization processing, and the sensitivity curve obtained after merging can be used to represent the total sensitivity after systemization, should Sensitivity on sensitivity curve at a corresponding wavelength points is the total sensitivity after the systemization at the wavelength points.It is preferred that Before systemization operation, can place first be normalized to sensitivity of multiple structural parameters respectively at each of which wavelength points in ground Reason.

Wherein, various ways can be used and carry out curve merging treatment.For example, based on the following formula to each wavelength points at The sensitivity of all structural parameters is averaged, and using the serial mean of each wavelength points of correspondence as each wavelength points at Total sensitivity after systemization is derived from the sensitivity curve after merging：

Wherein, SSt_Total(λ_i) it is wavelength points λ_iTotal sensitivity after the systemization at place；For structural parameters x_jIn ripple Long point λ_iThe sensitivity at place；L is the sum for all structural parameters for treating geodesic structure.

2）In this realization method, step S21 includes step S21-1 and step S21-2.

In step S21-1, computer equipment is by each structural parameters in the multiple structural parameters in each of which wavelength The sensitivity at point place is normalized, obtain multiple structural parameters respectively at each of which wavelength points, normalize after Sensitivity.

For example, for each structural parameters in multiple structural parameters, computer equipment can be tied this based on the following formula Sensitivity of the structure parameter at each wavelength points is normalized, come obtain the structural parameters at each wavelength points, Sensitivity after normalization：

Wherein,For structural parameters x_jIn wavelength points λ_iSensitivity locating, after normalization；For knot Structure parameter x_jIn wavelength points λ_iPlace, not normalized sensitivity；To consider that it is complete that selected all band is included When body wavelength points are contributed, structural parameters x_jSensitivity, wherein, all band is predetermined, for measuring Spectral band scope.

AsA kind of calculation, by taking the structural model to be measured shown in Fig. 6 as an example, using polarization state point The fourier coefficient α and β of analysis represents spectrum types, computer equipment can according to the following formula, calculate consider it is full wave complete When body wavelength points are contributed, the sensitivity of each structural parameters of structural model to be measured：

Wherein,Represent to consider structural parameters x during all wavelength points contributions_jSensitivity；N is all wavelength The quantity of point；With reference to formula above, can obtain：

Wherein, Sensitivity_CD, Sensitivity_SWAAnd Sensitivity_HTIt represents to consider respectively full wave complete When body wavelength points are contributed, the sensitivity of structural parameters CD, SWA, HT of the structural model to be measured shown in Fig. 6.Then, computer is set It is standby the sensitivity of structural parameters CD, SWA, HT at each wavelength points to be normalized according to the following formula：

Wherein,Represent structural parameters CD, SWA, HT in wavelength respectively Point λ_iSensitivity locating, after normalization.It is illustrated in figure 8 returning for three kinds of structural parameters of the structural model to be measured shown in Fig. 6 One change after sensitivity with wavelength distribution schematic diagram.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that it is any by each structural parameters in the multiple structural parameters in each of which wavelength points The sensitivity at place is normalized, obtain multiple structural parameters respectively at each of which wavelength points, spirit after normalization The realization method of sensitivity, should be included in the scope of the present invention.

In step S21-2, computer equipment is to the sensitivity after having the normalization of structural parameters at each wavelength points Systemization processing is carried out, obtains the total sensitivity after the systemization at each wavelength points.

Specifically, computer equipment carries out system to the sensitivity after having the normalization of structural parameters at each wavelength points Processing, the realization method for obtaining the total sensitivity after the systemization at each wavelength points include but not limited to：

1）Computer equipment is directly according to there is the sensitivity after the normalization of structural parameters at each wavelength points, to every There is the sensitivity after the normalization of structural parameters to carry out systemization processing at a wavelength points, after obtaining the system at each wavelength points Total sensitivity.

For example, computer equipment is according to the sensitivity after having the normalization of structural parameters at each wavelength points, and it is based on The following formula averages to the sensitivity after the normalization of all structural parameters at each wavelength points, and by each wavelength points pair The serial mean answered is as the total sensitivity after the systemization at each wavelength points：

Wherein,For wavelength points λ_iTotal sensitivity after the systemization at place；For structural parameters x_j Wavelength points λ_iSensitivity after the normalization at place；L is the quantity for all structural parameters for treating geodesic structure.

2）Preferably, computer equipment combines the respective systemization weight of the multiple structural parameters, at each wavelength points All structural parameters normalization after sensitivity carry out systemization processing, obtain after the systemization at each wavelength points it is described always Sensitivity.

Wherein, the systemization weight can be used for representing structural parameters to the percentage contribution of total sensitivity, the system of structural parameters It is higher to change weight, represents that the contribution of the sensitivity of the structural parameters is bigger；Preferably, knot can be determined based at least one of following The system weight of structure parameter：

i）Importance of the structural parameters in technology controlling and process corresponding to the systemization weight.

For example, for the polycrystalline silicon device structural model to be measured shown in Fig. 6, usually in integrated circuit planar manufacturing process In, structural parameters CD therein（Critical size）Importance highest in technology controlling and process, thus can setting structure parameter CD system Change weight is highest.

ii）User's attention rate of structural parameters corresponding to the systemization weight.

For example, for the structural model to be measured shown in Fig. 6, wherein, user's attention rate is followed successively by from high to low：Structural parameters CD, structural parameters SWA, structural parameters HT, thus can setting structure parameter CD system weight for highest, the system of structural parameters HT Weight is minimum.

As an example, computer equipment can be based on the following formula, and combine the respective system of the multiple structural parameters Change weight, systemization processing is carried out to the sensitivity after the normalization of all structural parameters at each wavelength points, obtains each ripple The total sensitivity after systemization at long point：

Wherein, w_jFor structural parameters x_jSystem weight.

For example, by taking the structural model to be measured shown in Fig. 6 as an example, the system weight difference of setting structure parameter CD, SWA, HT For w₁, w₂, w₃, then, total sensitivity of all structural parameters at each wavelength points can be obtained based on the following formula：

Wherein,WithIt is illustrated respectively in wavelength points λ_iPlace, structural parameters Sensitivity after the normalization of CD, SWA, HT；Represent structural parameters CD, SWA, HT in wavelength points λ_iThe system at place Total sensitivity afterwards.Fig. 9 is to take w₁=w₂=w₃Total sensitivity after the systemization of structural model to be measured when=1 shown in Fig. 6 is with wavelength Distribution schematic diagram；Wherein, transverse axis represents wavelength, and the longitudinal axis represents the total sensitivity after systemization；Wherein, the solid line is all knots For the total sensitivity of structure parameter with the distribution curve of wavelength, the dotted line is sensitivity screening threshold value.Figure 10 is to take w₁=20, w₂=2, w₃Total sensitivity after the systemization of structural model to be measured when=2 shown in Fig. 6 with wavelength distribution schematic diagram；Wherein, transverse axis represents Wavelength, the longitudinal axis represent the total sensitivity after systemization.By Fig. 9 and Figure 10 respectively compared with Fig. 7 it can be found that due to structure Parameter CD imparts higher system weight, therefore the total sensitivity in Figure 10 after systemization is with the knot in wavelength profile and Fig. 7 The sensitivity of structure parameter CD is closer to the shape of wavelength profile.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that it is any to have at each wavelength points the sensitivity after the normalization of structural parameters into Row systemization processing, obtains the realization method of the total sensitivity after the systemization at each wavelength points, should be included in the model of the present invention In enclosing.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that any sensitive at each of which wavelength points respectively according to the multiple structural parameters Degree carries out the sensitivity of all structural parameters at each wavelength points systemization processing, after obtaining the system at each wavelength points Total sensitivity realization method, should be included in the scope of the present invention.

In step S22, computer equipment screens one or more according to the total sensitivity after the systemization at each wavelength points A spectral band.

Specifically, computer equipment screens one or more light according to the total sensitivity after the systemization at each wavelength points The realization method of spectrum wave band includes but not limited to：

1）Sensitivity screening rule is manually set, and computer equipment is according to total sensitive after the systemization at each wavelength points Degree, and the sensitivity screening rule is combined, directly filter out the one or more spectral bands for meeting the sensitivity screening rule.

For example, the range of sensitivity that the setting of sensitivity screening rule meets screening conditions is（0.8,1.0）, then computer set For according to the total sensitivity after the systemization at each wavelength points, screening meets the range of sensitivity（0.8,1.0）One or more Wave band.

2）Preferably, before step S22, computer equipment is according to the system at each wavelength points obtained in step S21 Total sensitivity after change determines that threshold value is screened in sensitivity；In step S22, computer equipment according to each wavelength points at Systemization after total sensitivity, and with reference to the sensitivity screen threshold value, screen one or more of spectral bands.

For example, computer equipment can be based on the following formula, and come with reference to the total sensitivity after the systemization at each wavelength points Determine that threshold value is screened in sensitivity：

Wherein, T screens threshold value for sensitivity,For the total sensitivity after the systemization at each wavelength points In minimum value,For the maximum in the total sensitivity after the systemization at each wavelength points, η is sensitivity Coefficient is adjusted, can be manually adjusted according to demand.By taking tactic pattern to be measured shown in Fig. 6 as an example, when η values are 1/2, computer is set The total sensitivity after systemization at standby each wavelength points according to the structural model to be measured shown in Fig. 9, based on above-mentioned sensitivity It is T=0.976 that the calculation formula of screening threshold value, which can obtain sensitivity screening threshold value, as shown by the broken line in fig. 9；In step S22 In, computer equipment is according to the total sensitivity after the systemization at each wavelength points, and combination sensitivity screening threshold value can screen Go out to be more than three spectral bands of sensitivity screening threshold value, be respectively：（300,305）、（435,455）、（630,800）.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that the total sensitivity at each wavelength points of any basis after systemization, screening is one or more The realization method of spectral band, should be included in the scope of the present invention.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that any sensitive at each of which wavelength points respectively according to the multiple structural parameters Degree screens the realization method of one or more spectral bands, should be included in the scope of the present invention.

As a kind of preferred embodiment of the present embodiment, the method for the present embodiment is additionally included in step S1 and performs following step before Suddenly：Each structural parameters in multiple structural parameters of geodesic structure model are treated, under given measurement pattern, the structure of floating ginseng Number obtains spectral signal offset of the structural parameters at its each wavelength points spectrally.Preferably, it is described to give location survey Amount pattern is that disclosure satisfy that the optimum measurement pattern of measurement demand.

Preferably, each structural parameters in multiple structural parameters of geodesic structure model are treated, under given measurement pattern, Structural parameters beyond the structural parameters are arranged at its nominal value by computer equipment, are obtained the structural parameters value and are marked for it The spectroscopic data and the structural parameters value generated during value on structural model to be measured is referred to as that its nominal value fluctuates Two spectroscopic datas generated after default worst error value during gained two values on structural model to be measured, and according to above-mentioned three Spectroscopic data obtains spectral signal offset of the structural parameters at its each wavelength points spectrally.

Wherein, the default worst error value is used to represent the error range that the structural parameters allow.For example, structural parameters Default worst error value for 0.1, the error range for representing the structural parameters is（- 0.1 ,+0.1）.

Wherein, a variety of computational methods can be used to handle spectroscopic data, obtains structural parameters at it spectrally Spectral signal offset at each wavelength points, such as mean square error computational methods, root-mean-square error computational methods, average absolute hundred Divide error calculation method.

For example, for the structural model to be measured shown in Fig. 6, using the fourier coefficient α and β for Polarization come table Show spectrum types, computer equipment can obtain spectral signal of the structural parameters at each wavelength points according to the following formula and deviate Amount.

Wherein,

Wherein, x represents all structural parameters involved by structural model to be measured；Δx_jRepresent structural parameters x_jIt is default most Big error amount can be considered being equivalent to structural parameters x_jControllable measurement accuracy；ΔS(x,Δx_j,λ_i) represent structural parameters x_j In wavelength points λ_iThe spectral signal offset at place；ΔS⁺(x,Δx_j,λ_i) represent structural parameters x_jIn wavelength points λ_iPlace is based on its mark Title value floating+Δ x_jWhen the spectroscopic data that generates and the spectroscopic data that generates when being nominal value of its value between spectral signal it is inclined Shifting amount；ΔS^-(x,Δx_j,λ_i) represent structural parameters x_jIn wavelength points λ_iPlace is based on its nominal value floating-Δ x_jWhen the spectrum that generates Spectral signal offset between the spectroscopic data that data and its value generate when being nominal value；s(x,+Δx_j,λ_i) represent structure Parameter x_jBased on its nominal value floating+Δ x_jWhen in wavelength points λ_iLocate the spectroscopic data generated；s(x,0,λ_i) represent structural parameters x_j For its nominal value when in wavelength points λ_iLocate the spectroscopic data generated；s(x,-Δx_j,λ_i) represent structural parameters x_jBased on its nominal value Floating-Δ x_jWhen in wavelength points λ_iLocate the spectroscopic data generated.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that each structural parameters in any multiple structural parameters for treating geodesic structure model, Under given measurement pattern, the structural parameters are floated to obtain spectrum letter of the structural parameters at its each wavelength points spectrally The realization method of number offset, should be included in the scope of the present invention.

As a kind of preferred embodiment of the present embodiment, the method for this implementation is additionally included in step S1 and performs following step before Suddenly：Computer equipment treats the material of geodesic structure and the structural parameters according to, establishes the structural model to be measured.

For example, for the geodesic structure for the treatment of shown in Fig. 6, material includes：Silicon, silica, polysilicon.Its structural parameters bag It includes：Critical size CD, Sidewall angles SWA, gate height HT.Computer equipment is nominal according to above-mentioned material and structural parameters Value, can establish the structural model to be measured shown in Fig. 6.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that any basis treats the material and structural parameters of geodesic structure, establishes structural model to be measured Realization method should be included in the scope of the present invention.

Distribution of the sensitivity of different device under test and process structure parameters on wavelength dimension is different, and existing Technology cannot combine the specific structural parameters for treating geodesic structure, and pin is made to the fitting weight of spectral wavelength ranges and different wave length wave band Setting to property, therefore be unfavorable for the signal-to-noise ratio of OCD measurements and the further improvement of accuracy and promoted.And according to the present embodiment Method, can be by the sensitivity analysis for each structural parameters for treating geodesic structure model under given measurement pattern, and combine The system weight of each structural parameters, to screen the one or more spectral bands for meeting screening rule.Make it possible to flexible While importance and user attention rate of the ground integrated structure parameter in technology controlling and process, based on the sensitive of each structural parameters Analysis result is spent, realizing has fitting weight coefficient of each sub-band with different sensitivity feature in fitting is evaluated Machine is set, and so as to improve the signal-to-noise ratio and accuracy of OCD fittings, and promotes the stability of measurement.

Fig. 2 is that the flow of the method in OCD measurements for screening wave band of another preferred embodiment of the present invention is shown It is intended to.Wherein, the method for the present embodiment is mainly realized by computer equipment, wherein, to reference to institute in embodiment illustrated in fig. 1 Any explanation for the computer equipment stated, by reference comprising in this present embodiment.Wherein, the method bag of the present embodiment Include step S1, step S2, step S3, step S4 and step S5.Wherein, step S1 and step S2 gives in detail in reference to Fig. 1 It states, details are not described herein.

In the present embodiment, a spectral band in one or more spectral bands for filtering out in step s 2 is performed Following step S3, step S4 and step S5.Preferably for each spectral band in one or more spectral bands, Perform step S3, step S4 and step S5.

In step s3, computer equipment according to multiple structural parameters of structural model to be measured respectively in currently processed light At each wavelength points of wave band, not normalized sensitivity are composed, each structural parameters in the multiple structural parameters is obtained and exists Not normalized sensitivity in the spectral band.

Wherein, not normalized sensitivity of the structural parameters in the spectral band is considered in the spectral band The contribution of all wavelength points, i.e., for a structural parameters, a spectral band corresponds to not normalized sensitivity.

For example, computer equipment can be based on the following formula, according to the multiple structural parameters respectively in the spectral band Sensitivity at each wavelength points, not normalized obtain in the multiple structural parameters each structural parameters in the spectrum ripple Not normalized sensitivity in section：

Wherein,Represent structural parameters x_jIn spectral band λ_Sub-BandIn the range of it is not normalized sensitive Degree；Represent structural parameters x_jIn wavelength points λ_iPlace, not normalized sensitivity, n is spectral band λ_Sub-BandInterior wavelength points quantity, λ_i(i=1,...,n),n≤N。

For example, based on the structural model to be measured shown in Fig. 6, λ_Sub-BandOne filtered out in step s 2 for computer equipment A spectral band；In step s3, computer equipment can determine the structural parameters of the structural model to be measured according to the following formula CD, SWA, HT are in spectral band λ_Sub-BandIn the range of not normalized sensitivity：

Wherein, Sensitivity'_CD、Sensitivity'_SWAAnd Sensitivity'_HTRepresent respectively structural parameters CD, SWA, HT are in spectral band λ_Sub-BandIn the range of not normalized sensitivity；SSt_CD(λ_i), SSt_SWA(λ_i) and SSt_HT(λ_i) point Not Biao Shi structural parameters CD, SWA, HT in wavelength points λ_iPlace, not normalized sensitivity；

In step s 4, computer equipment to each structural parameters in the multiple structural parameters in the spectral band Not normalized sensitivity carries out systemization processing, determines the sensitivity after the systemization of the spectral band.

Specifically, computer equipment is not to each structural parameters returning in the spectral band in the multiple structural parameters One sensitivity changed carries out systemization and handles, and determining the realization method of the sensitivity after the systemization of the spectral band includes but unlimited In：

1）Computer equipment is directly based upon in the multiple structural parameters each structural parameters in the spectral band not Normalized sensitivity, it is not normalized sensitive in the spectral band to each structural parameters in the multiple structural parameters Degree carries out systemization processing, determines the sensitivity after the systemization of the spectral band.

For example, computer equipment is based on the following formula to each structural parameters in the multiple structural parameters in the spectrum ripple Not normalized sensitivity in section is averaged, and using the corresponding serial mean of each wavelength points as the spectral band Sensitivity after systemization：

Wherein, Sensitivity_Sub-BandRepresent wave band λ_Sub-BandSystemization after sensitivity；Geodesic structure mould is treated in L expressions The number of structural parameters included by type, x_j,j=0,...,L-1。

2）Computer equipment combines the respective systemization weight of the multiple structural parameters, to every in the multiple structural parameters Not normalized sensitivity of a structural parameters in the spectral band carries out systemization and handles, after the system for determining the spectral band Sensitivity.

As an example, computer equipment can be based on the following formula and combine the respective systemization power of the multiple structural parameters Weight, carries out at systemization not normalized sensitivity of each structural parameters in the spectral band in the multiple structural parameters Reason, determines the sensitivity after the systemization of the spectral band：

For example, based on the structural model to be measured shown in Fig. 6, in step s3, computer equipment obtain structural parameters CD, SWA, HT are in spectral band λ_Sub-BandIn the range of not normalized sensitivity be respectively Sensitivity'_CD、 Sensitivity'_SWA、Sensitivity'_HT；In step s 4, computer equipment determines spectral band λ_Sub-BandSystem after Sensitivity be：

Wherein, w₁, w₂, w₃The respectively system weight of structural parameters CD, SWA, HT.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that it is any to each structural parameters in the multiple structural parameters in the spectral band Not normalized sensitivity carry out systemization processing, determine the realization method of the sensitivity after the systemization of the spectral band, should all Within the scope of the present invention.

In step s 5, after computer equipment is according to the sensitivity after the systemization of the spectral band and full wave systemization Sensitivity, determine the ratio of the sensitivity after the sensitivity after the systemization of the spectral band and full wave systemization, and according to The ratio determines coefficient of the spectral band in spectrum simulation.

Wherein, computer equipment determines the realization method of the sensitivity after full wave systemization with determining screening in step S4 The realization method of sensitivity after the systemization of the spectral band gone out is same or similar, and details are not described herein.

Wherein, computer equipment can be used various ways according to the sensitivity after the systemization of the spectral band with it is full wave The ratio of sensitivity after systemization, to determine coefficient of the spectral band in spectrum simulation.

For example, computer equipment can according to the sensitivity after the systemization of the spectral band with it is sensitive after full wave systemization The ratio of degree determines coefficient of the spectral band in spectrum simulation based on predetermined formula, as computer equipment can be based on Lower formula, according to spectral band λ_Sub-BandSystemization after sensitivity and all band λ_Full-BandSystemization after sensitivity ratio Value, to determine coefficient of the spectral band in spectrum simulation：

Wherein, Sensitivity_Sub-BandFor spectral band λ_Sub-Band∈(λ_a,λ_b) sensitivity； Sensitivity_{Full Band}For all band λ_{Full Band}∈(λ_Start,λ_End) sensitivity；υ_Sub-BandIt represents in spectrum simulation Spectral band λ_Sub-Band∈(λ_a,λ_b) coefficient；υ_TotalFor full wave fitting coefficient, 1 usually can be taken as；ξ represents sub-band Fitting weight adjustment factor, can manually be adjusted according to demand.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that sensitivity and full wave systemization after any systemization according to the spectral band Sensitivity afterwards determines the ratio of the sensitivity after the systemization of the spectral band and the sensitivity after full wave systemization, and root The realization method of coefficient of the spectral band in spectrum simulation is determined according to the ratio, should be included in the scope of the present invention It is interior.

According to the method for the present embodiment, the system weight of each structural parameters can be combined, come determine filter out one or The ratio between the sensitivity after sensitivity and full wave systemization after the systemization of multiple spectral bands, so that it is determined that this Or coefficient of multiple spectral bands when carrying out spectrum simulation so that can to different wavelength regions fitting when coefficient into Row is targetedly set, so as to greatly improve the Stability and veracity of OCD measurement results.

Fig. 3 is the wave band screening plant for being used to screen wave band in OCD measurements of a preferred embodiment of the present invention Structure diagram, wherein, the screening wave band refers to sub-band of the screening with different sensitivity feature.

First determining device 1 and screening plant 2 are included according to the wave band screening plant of the present embodiment.

For each structural parameters in multiple structural parameters of structural model to be measured, the first determining device 1 is according to by this The variation of structural parameters and caused by corresponding spectrally each wavelength points spectral signal offset, determine the structural parameters in institute State the sensitivity at each wavelength points；Wherein, as the variation of structural parameters and caused by corresponding spectrally each wavelength points light Spectrum signal offset can be the theoretical spectral data of nominal value and neighbor that structural parameters are calculated beforehand through certain mode Between difference obtain, be then provided directly to the first determining device 1 or be calculated by wave band screening plant , should be calculated as wave band screening plant as the variation of structural parameters and caused by corresponding spectrally each wavelength points spectral signal The concrete mode of offset will be described in detail in following embodiment.The operation then performed by the first determining device 1, it may be determined that Each sensitivity of the structural parameters at each wavelength points in multiple structural parameters.Wherein, the variation of said structure parameter is often It is small.

Wherein, the structural model to be measured is the simulation model for treating geodesic structure, for that can represent to treat the material of geodesic structure And the model of structural information；Wherein, the structural parameters can be for representing each of the structure feature of the structural model to be measured Kind of parameter, for example, the critical size CD of structural model to be measured, film thickness, Sidewall angles SWA and height HT, trapezoidal footing and Tip circle etc..

For example, Fig. 6 is the structural model schematic diagram to be measured of gained after polysilicon structure simulation to be measured, the structural model to be measured It can represent that polysilicon treats the material and structural information of geodesic structure.It will be appreciated from fig. 6 that this treats the material of geodesic structure from the bottom up successively For：Silicon, silica, polysilicon（poly）；This treats that the structural parameters of geodesic structure include：Critical size CD, Sidewall angles SWA, Polysilicon gate height HT etc..

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that it is any for representing the various parameters of the structure feature of the structural model to be measured, It should be included in as defined in the range of the structural parameters of the present invention.

Preferably for each structural parameters in multiple structural parameters of structural model to be measured, the first determining device 1 can The spectral signal offset of corresponding spectrally each wavelength points caused by according to the variation as the structural parameters, and in selected ripple Section determines sensitivity of the structural parameters at each wavelength points based on the sensitivity formula.

For example, for the structural model to be measured shown in Fig. 6, the structural parameters of the structural model to be measured include：Critical size CD, Sidewall angles SWA, gate height HT.First determining device 1 can respectively be calculated according to the following formula structural parameters CD, SWA, HT is in wavelength points λ_iThe sensitivity at place：

Wherein, x is parameter vector, represents each structural parameters involved by structural model to be measured（In this example, by structure Parameter CD, SWA and HT describe to treat the profile of geodesic structure, then x=[CD, SWA, HT] expressions are made of CD, SWA and HT structure Parameter vector）.Represent structural parameters x_jIn wavelength points λ_iThe sensitivity at place, x_jRepresent that some that investigation is waited in x is tied Structure parameter, Δ x_jRepresent structural parameters x_jFloat value near its nominal value, Δ S (x, Δ x_j,λ_i) represent structural parameters x_j Certain wavelength points λ_iSpectral signal offset at (i=1 ..., N), the wavelength that wave band selected by N expressions is included are counted out.It will be real Involved specific structural parameters name code to be measured replaces Δ x in example_j, there is following formula：

Wherein, SSt_CD(λ_i), SSt_SWA(λ_i) and SSt_HT(λ_i) represent structural parameters CD, SWA and HT in wavelength points λ respectively_i The sensitivity at place.Fig. 7 is that the sensitivity of three kinds of structural parameters of the structural model to be measured shown in Fig. 6 is illustrated with the distribution of wavelength Scheme, three curves in figure are respectively the sensitivity of structural parameters CD, SWA, HT of the structural model to be measured shown in Fig. 6 with wavelength Distribution curve, wherein, transverse axis represent wavelength, the longitudinal axis represent sensitivity.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that each structural parameters in any multiple structural parameters for structural model to be measured, The spectral signal offset of corresponding spectrally each wavelength points, determines the structure caused by according to the variation as the structural parameters The realization method of sensitivity of the parameter at each wavelength points, should be included in the scope of the present invention.

Screening plant 2 according to multiple structural parameters sensitivity at each of which wavelength points respectively of structural model to be measured, The one or more spectral bands of screening.

Specifically, various ways can be used according to the multiple structural parameters respectively in each of which wavelength points in screening plant 2 One or more spectral bands are screened in the sensitivity at place.

For example, a threshold of sensitivity, screening plant 2 manually are respectively provided with to each structural parameters in multiple structural parameters According to the sensitivity at each of which wavelength points respectively of the multiple structural parameters, and such threshold of sensitivity is combined, directly sieved Select one or more spectral bands；At each wavelength points in the one or more spectral bands filtered out, Mei Gejie The sensitivity of structure parameter is above the corresponding threshold of sensitivity of the structural parameters.

In another example a unified threshold of sensitivity is manually set.Before spectral band is screened, screening plant 2 is to more Each sensitivity of the structural parameters at each wavelength points is normalized in a structural parameters, and according to normalized Rear sensitivity and the unified threshold of sensitivity screen one or more spectral bands；Wherein, the one or more quilt At each wavelength points in the spectral band filtered out, the sensitivity of each structural parameters is above the unified threshold of sensitivity Value.

As a kind of preferred embodiment of screening plant 2, screening plant 2 includes the first acquisition device（It is not shown）With the first son Screening plant（It is not shown）.

First acquisition device is according to the sensitivity at each of which wavelength points respectively of the multiple structural parameters, to each ripple The sensitivity of all structural parameters at long point carries out systemization processing, obtains the total sensitivity after the systemization at each wavelength points.

Wherein, systemization processing is carried out to the sensitivity of all structural parameters at a wavelength points, is represented the wavelength The corresponding multiple sensitivity processing of all structural parameters at point are corresponding with the wavelength points, can reflect all structures One sensitivity of the overall sensitivity of parameter；For example, to all structural parameters HT, CD at wavelength points 390 shown in Fig. 8 and Corresponding three sensitivity of SWA carry out systemization processing, can obtain it is at wavelength points 390 shown in Fig. 9, can reflect One sensitivity of the overall sensitivity of structural parameters HT, CD and SWA.

Specifically, the first acquisition device is according to the sensitivity at each of which wavelength points respectively of the multiple structural parameters, Systemization processing is carried out to the sensitivity of all structural parameters at each wavelength points, is obtained total after the systemization at each wavelength points The realization method of sensitivity includes but not limited to：

1）First acquisition device is drawn more according to the sensitivity at each of which wavelength points respectively of the multiple structural parameters The sensitivity curve of each structural parameters in a structural parameters is merged by curve to all structural parameters at each wavelength points Sensitivity carry out systemization processing, the sensitivity curve obtained after merging can be used to represent systemization after total sensitivity, Sensitivity on this sensitivity curve at a corresponding wavelength points is the total sensitivity after the systemization at the wavelength points.It is excellent Selection of land before systemization operation, can first be normalized sensitivity of multiple structural parameters respectively at each of which wavelength points Processing.

Wherein, the first acquisition device can be used various ways and carry out curve merging treatment.For example, based on the following formula to every The sensitivity of all structural parameters at a wavelength points is averaged, and using the serial mean of each wavelength points of correspondence as The total sensitivity after systemization at each wavelength points, is derived from the sensitivity curve after merging：

Wherein, SSt_Total(λ_i) it is wavelength points λ_iTotal sensitivity after the systemization at place；For structural parameters x_jIn ripple Long point λ_iThe sensitivity at place；L is the total x for all structural parameters for treating geodesic structure_j,j=0,...,L-1。

2）In this realization method, the first acquisition device includes the first sub- acquisition device（It is not shown）With the second sub- acquisition device （It is not shown）.

First sub- acquisition device is sensitive at each of which wavelength points by each structural parameters in the multiple structural parameters Degree is normalized, obtain multiple structural parameters respectively at each of which wavelength points, sensitivity after normalization.

For example, for each structural parameters in multiple structural parameters, the first sub- acquisition device can be based on the following formula will Sensitivity of the structural parameters at each wavelength points is normalized, to obtain the structural parameters at each wavelength points , normalization after sensitivity：

Wherein,For structural parameters x_jIn wavelength points λ_iSensitivity locating, after normalization；For knot Structure parameter x_jIn wavelength points λ_iPlace, not normalized sensitivity；To consider that it is complete that selected all band is included When body wavelength points are contributed, structural parameters x_jSensitivity, wherein, all band is predetermined, for measuring Spectral band scope.

AsA kind of calculation, by taking the structural model to be measured shown in Fig. 6 as an example, using polarization state point The fourier coefficient α and β of analysis represents spectrum types, and the first sub- acquisition device can calculate according to the following formula and consider all band All wavelength points contribution when, the sensitivity of each structural parameters of structural model to be measured：

Wherein,Structural parameters x when representing to consider all wavelength points contributions_jSensitivity；N is all ripples The quantity of long point；With reference to formula above, can obtain：

Wherein, Sensitivity_CD, Sensitivity_SWAAnd Sensitivity_HTIt represents to consider respectively full wave complete When body wavelength points are contributed, the sensitivity of structural parameters CD, SWA, HT of the structural model to be measured shown in Fig. 6.Then, the first son obtains Device is taken the sensitivity of structural parameters CD, SWA, HT at each wavelength points can be normalized according to the following formula：

Wherein,WithRepresent structural parameters CD, SWA, HT in wavelength respectively Point λ_iSensitivity locating, after normalization.It is illustrated in figure 8 returning for three kinds of structural parameters of the structural model to be measured shown in Fig. 6 One change after sensitivity with wavelength distribution schematic diagram.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that it is any by each structural parameters in the multiple structural parameters in each of which wavelength points The sensitivity at place is normalized, obtain multiple structural parameters respectively at each of which wavelength points, spirit after normalization The realization method of sensitivity, should be included in the scope of the present invention.

Second sub- acquisition device carries out systemization place to the sensitivity after having the normalization of structural parameters at each wavelength points Reason, obtains the total sensitivity after the systemization at each wavelength points.

Specifically, the second sub- acquisition device carries out the sensitivity after having the normalization of structural parameters at each wavelength points Systemization processing, the realization method for obtaining the total sensitivity after the systemization at each wavelength points include but not limited to：

1）Second sub- acquisition device directly according to there is the sensitivity after the normalization of structural parameters at each wavelength points, comes To there is the sensitivity after the normalization of structural parameters to carry out systemization processing at each wavelength points, the system at each wavelength points is obtained Total sensitivity after change.

For example, the second sub- acquisition device is according to the sensitivity after having the normalization of structural parameters at each wavelength points, and It is averaged based on the following formula to the sensitivity after the normalization of all structural parameters at each wavelength points, and by each wavelength The corresponding serial mean of point is as the total sensitivity after systemization at each wavelength points：

Wherein,For wavelength points λ_iTotal sensitivity after the systemization at place；For structural parameters x_jIn ripple Long point λ_iSensitivity after the normalization at place；L is the quantity for all structural parameters for treating geodesic structure.

2）Preferably, the second sub- acquisition device includes the 3rd sub- acquisition device（It is not shown）.3rd sub- acquisition device combines The multiple respective systemization weight of structural parameters, to the sensitivity after the normalization of all structural parameters at each wavelength points Systemization processing is carried out, obtains the total sensitivity after systemization at each wavelength points.

Wherein, the systemization weight can be used for representing structural parameters to the percentage contribution of total sensitivity, the system of structural parameters It is higher to change weight, represents that the contribution of the sensitivity of the structural parameters is bigger；Preferably, knot can be determined based at least one of following The system weight of structure parameter：

i）Importance of the structural parameters in technology controlling and process corresponding to the systemization weight.

For example, for the polycrystalline silicon device structural model to be measured shown in Fig. 6, usually in integrated circuit planar manufacturing process In, structural parameters CD therein（Critical size）Importance highest in technology controlling and process, thus can setting structure parameter CD system Change weight is highest.

ii）User's attention rate of structural parameters corresponding to the systemization weight.

For example, for the structural model to be measured shown in Fig. 6, wherein, user's attention rate is followed successively by from high to low：Structural parameters CD, structural parameters SWA, structural parameters HT, thus can setting structure parameter CD system weight for highest, the system of structural parameters HT Weight is minimum.

As an example, the 3rd sub- acquisition device can be based on the following formula, and combine the multiple structural parameters each System weight, systemization processing is carried out to the sensitivity after the normalization of all structural parameters at each wavelength points, is obtained every The total sensitivity at a wavelength points after systemization：

Wherein, w_jFor structural parameters x_jSystem weight.

For example, by taking the structural model to be measured shown in Fig. 6 as an example, the system weight difference of setting structure parameter CD, SWA, HT For w₁, w₂, w₃, then, the 3rd sub- acquisition device can obtain total spirit of all structural parameters at each wavelength points based on the following formula Sensitivity：

Wherein,WithIt is illustrated respectively in wavelength points λ_iPlace, structural parameters Sensitivity after the normalization of CD, SWA, HT；Represent structural parameters CD, SWA, HT in wavelength points λ_iThe system at place Total sensitivity afterwards.Fig. 9 is to take w₁=w₂=w₃Total sensitivity after the systemization of structural model to be measured when=1 shown in Fig. 6 is with wavelength Distribution schematic diagram；Wherein, transverse axis represents wavelength, and the longitudinal axis represents the total sensitivity after systemization；Wherein, the solid line is all knots For the total sensitivity of structure parameter with the distribution curve of wavelength, the dotted line is sensitivity screening threshold value.Figure 10 is to take w₁=20, w₂=2, w₃Total sensitivity after the systemization of structural model to be measured when=2 shown in Fig. 6 with wavelength distribution schematic diagram；Wherein, transverse axis represents Wavelength, the longitudinal axis represent the total sensitivity after systemization.By Fig. 9 and Figure 10 respectively compared with Fig. 7 it can be found that due to structure Parameter CD imparts higher system weight, therefore the total sensitivity in Figure 10 after systemization is with the knot in wavelength profile and Fig. 7 The sensitivity of structure parameter CD is closer to the shape of wavelength profile.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that it is any to have at each wavelength points the sensitivity after the normalization of structural parameters into Row systemization processing, obtains the realization method of the total sensitivity after the systemization at each wavelength points, should be included in the model of the present invention In enclosing.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that any sensitive at each of which wavelength points respectively according to the multiple structural parameters Degree carries out the sensitivity of all structural parameters at each wavelength points systemization processing, after obtaining the system at each wavelength points Total sensitivity realization method, should be included in the scope of the present invention.

First sub- screening plant screens one or more spectrum ripples according to the total sensitivity after the systemization at each wavelength points Section.

Specifically, the first sub- screening plant screens one or more according to the total sensitivity after the systemization at each wavelength points The realization method of a spectral band includes but not limited to：

1）Sensitivity screening rule is manually set, and the first sub- screening plant is according to total sensitive after systemization at each wavelength points Degree, and the sensitivity screening rule is combined, directly filter out the one or more spectral bands for meeting the sensitivity screening rule.

For example, the range of sensitivity that the setting of sensitivity screening rule meets screening conditions is（0.8,1.0）, then first son sieve Screening device meets the range of sensitivity according to the total sensitivity after the systemization at each wavelength points, screening（0.8,1.0）One or Multiple wave bands.

2）Preferably, screening plant 2 includes the second determining device（It is not shown）, the first sub- screening plant include second son sieve Screening device（It is not shown）.Before the second sub- screening plant performs operation, the second determining device is obtained according to the first acquisition device Each wavelength points at systemization after total sensitivity, determine sensitivity screen threshold value；Second sub- screening plant is according to described every Total sensitivity at a wavelength points after systemization, and threshold value is screened with reference to the sensitivity, screen one or more of spectrum ripples Section.

For example, the second determining device can be based on the following formula, and combine the total sensitivity after the systemization at each wavelength points To determine that threshold value is screened in sensitivity：

Wherein, T screens threshold value for sensitivity,For the total sensitivity after the systemization at each wavelength points In minimum value,For the maximum in the total sensitivity after systemization at each wavelength points, η is sensitivity tune Coefficient can manually be adjusted according to demand.By taking tactic pattern to be measured shown in Fig. 6 as an example, when η values are 1/2, second determines dress The total sensitivity after the systemization at each wavelength points according to the structural model to be measured shown in Fig. 9 is put, based on above-mentioned sensitivity It is T=0.976 that the calculation formula of screening threshold value, which can obtain sensitivity screening threshold value, as shown by the broken line in fig. 9；Second son screening Device is according to the total sensitivity after the systemization at each wavelength points, and combination sensitivity screening threshold value can be filtered out more than the spirit Sensitivity screens three spectral bands of threshold value, is respectively：（300,305）、（435,455）、（630,800）.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention It makes, it should be appreciated by those skilled in the art that the total sensitivity after the systemization at each wavelength points of any basis, screens one or more The realization method of a spectral band, should be included in the scope of the present invention.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that any sensitive at each of which wavelength points respectively according to the multiple structural parameters Degree screens the realization method of one or more spectral bands, should be included in the scope of the present invention.

As a kind of preferred embodiment of the present embodiment, the wave band screening plant of the present embodiment is additionally included in the first determining device The 3rd acquisition device of operation is performed before 1（It is not shown）.Treat each structure in multiple structural parameters of geodesic structure model Parameter, under the given measurement pattern, the 3rd acquisition device floats the structural parameters to obtain the structural parameters at it spectrally Spectral signal offset at each wavelength points.Preferably, the given measurement pattern is disclosure satisfy that measurement demand optimal Measurement pattern.

Preferably, each structural parameters in multiple structural parameters of geodesic structure model are treated, under given measurement pattern, Structural parameters beyond the structural parameters are arranged at its nominal value by the 3rd acquisition device, obtain the structural parameters value as it The spectroscopic data generated during nominal value on structural model to be measured and the structural parameters value are to be floated downward on its nominal value Two spectroscopic datas generated after dynamic default worst error value during gained two values on structural model to be measured, and according to above-mentioned Three spectroscopic datas obtain spectral signal offset of the structural parameters at its each wavelength points spectrally.

Wherein, the default worst error value, for representing the error range of structural parameters permission.For example, structure is joined Several default worst error values is 0.1, and the error range for representing the structural parameters is（- 0.1 ,+0.1）.

Wherein, a variety of computational methods can be used to handle spectroscopic data, obtains structural parameters at it spectrally Spectral signal offset at each wavelength points, such as mean square error computational methods, root-mean-square error computational methods, average absolute hundred Divide error calculation method.

For example, for the structural model to be measured shown in Fig. 6, using the fourier coefficient α and β for Polarization come table Show spectrum types, the 3rd acquisition device can obtain spectral signal of the structural parameters at each wavelength points according to the following formula and deviate Amount.

Wherein,

Wherein, x represents all structural parameters involved by structural model to be measured；Δx_jRepresent structural parameters x_jIt is default most Big error amount can be considered being equivalent to the controllable measurement accuracy of structural parameters xj；ΔS(x,Δx_j,λ_i) represent structural parameters xj In wavelength points λ_iThe spectral signal offset at place；ΔS⁺(x,Δx_j,λ_i) represent structural parameters x_jIn wavelength points λ_iPlace is based on its mark Title value floating+Δ x_jWhen the spectroscopic data that generates and the spectroscopic data that generates when being nominal value of its value between spectral signal it is inclined Shifting amount；ΔS^-(x,Δx_j,λ_i) represent structural parameters xj in wavelength points λ_iPlace is based on its nominal value floating-Δ x_jWhen the spectrum that generates Spectral signal offset between the spectroscopic data that data and its value generate when being nominal value；s(x,+Δx_j,λ_i) represent structure Parameter xj is based on its nominal value floating+Δ x_jWhen in wavelength points λ_iLocate the spectroscopic data generated；s(x,0,λ_i) represent structural parameters In wavelength points λ when xj is its nominal value_iLocate the spectroscopic data generated；s(x,-Δx_j,λ_i) represent structural parameters x_jIt is nominal based on it It is worth floating-Δ x_jWhen in wavelength points λ_iLocate the spectroscopic data generated.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that each structural parameters in any multiple structural parameters for treating geodesic structure model, Under given measurement pattern, the structural parameters are floated to obtain spectrum letter of the structural parameters at its each wavelength points spectrally The realization method of number offset, should be included in the scope of the present invention.

As a kind of preferred embodiment of the present embodiment, the wave band screening plant of this implementation is additionally included in the first determining device 1 The model foundation device of operation is performed before（It is not shown）.Model foundation device treats the material of geodesic structure and the knot according to Structure parameter establishes the structural model to be measured.

For example, for the geodesic structure for the treatment of shown in Fig. 6, material includes：Silicon, silica, polysilicon.Its structural parameters bag It includes：Critical size CD, Sidewall angles SWA, gate height HT.Model foundation device is nominal according to above-mentioned material and structural parameters Value, can establish the structural model to be measured shown in Fig. 6.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that any basis treats the material and structural parameters of geodesic structure, establishes structural model to be measured Realization method should be included in the scope of the present invention.

Distribution of the sensitivity of different device under test and process structure parameters on wavelength dimension is different, and existing Technology cannot combine the specific structural parameters for treating geodesic structure, and pin is made to the fitting weight of spectral wavelength ranges and different wave length wave band Setting to property, therefore be unfavorable for the signal-to-noise ratio of OCD measurements and the further improvement of accuracy and promoted.And according to the present embodiment Wave band screening plant, under given measurement pattern, the sensitivity point for each structural parameters for treating geodesic structure model can be passed through Analysis, and the system weight of each structural parameters is combined, to screen the one or more spectral bands for meeting screening rule.It makes it possible to It is enough while importance and user attention rate of the neatly integrated structure parameter in technology controlling and process, joined based on each structure Several sensitivity analysis are as a result, realize the fitting weight system to each sub-band with different sensitivity feature in fitting is evaluated Number carries out organic setting, so as to improve the signal-to-noise ratio and accuracy of OCD fittings, and promotes the stability of measurement.

Fig. 4 is the wave band screening plant for being used to screen wave band in OCD measurements of another preferred embodiment of the present invention Structure diagram.Wherein, the wave band screening plant of the present embodiment includes the first determining device 1, screening plant 2, second obtains Device 3, the 3rd determining device 4 and the 4th determining device 5.Wherein, the first determining device 1 and screening plant 2 are in reference to Fig. 3 It is described in detail, details are not described herein.

In the present embodiment, the second acquisition device 3, the 3rd determining device 4 and the 4th determining device 5 are used for screening plant 2 A spectral band in the one or more spectral bands filtered out performs operation.Preferably for one or more spectrum Each spectral band in wave band can trigger the second acquisition device 3, the 3rd determining device 4 and the 4th determining device 5 and perform behaviour Make.

Second acquisition device 3 is according to multiple structural parameters of structural model to be measured respectively in currently processed spectral band Sensitivity at each wavelength points, not normalized obtain in the multiple structural parameters each structural parameters in the spectrum ripple Not normalized sensitivity in section.

Wherein, not normalized sensitivity of the structural parameters in the spectral band is considered in the spectral band The contribution of all wavelength points, i.e., for a structural parameters, a spectral band corresponds to not normalized sensitivity.

For example, the second acquisition device 3 can be based on the following formula, according to the multiple structural parameters respectively in the spectral band Each wavelength points at, not normalized sensitivity, obtain in the multiple structural parameters each structural parameters in the spectrum Not normalized sensitivity in wave band：

Wherein,Represent structural parameters x_jIn spectral band λ_Sub-BandIn the range of it is not normalized sensitive Degree；Represent structural parameters x_jIn wavelength points λ_iPlace, not normalized sensitivity, n is spectral band λ_Sub-BandInterior wavelength points quantity, λ_i(i=1,...,n),n≤N。

For example, based on the structural model to be measured shown in Fig. 6, λ_Sub-BandThe spectral band filtered out for screening plant 2； Second acquisition device 3 can determine structural parameters CD, SWA, HT of the structural model to be measured in the spectrum ripple according to the following formula Section λ_Sub-BandIn the range of not normalized sensitivity：

Wherein, Sensitivity'_CD、Sensitivity'_SWAAnd Sensitivity'_HTRepresent respectively structural parameters CD, SWA, HT are in spectral band λ_Sub-BandIn the range of not normalized sensitivity；SSt_CD(λ i), SSt_SWA(λ i) and SSt_HT(λi) Represent structural parameters CD, SWA, HT in wavelength points λ respectively_iPlace, not normalized sensitivity；

3rd determining device 4 is not to each structural parameters normalizing in the spectral band in the multiple structural parameters Sensitivity carry out systemization processing, determine the sensitivity after the systemization of the spectral band.

Specifically, the 3rd determining device 4 to each structural parameters in the multiple structural parameters in the spectral band Not normalized sensitivity carries out systemization processing, determines the realization method of the sensitivity after the systemization of the spectral band and includes but not It is limited to：

1）3rd determining device 4 is directly based upon in the multiple structural parameters each structural parameters in the spectral band Not normalized sensitivity, to not normalized spirit of each structural parameters in the spectral band in the multiple structural parameters Sensitivity carries out systemization processing, determines the sensitivity after the systemization of the spectral band.

For example, the 3rd determining device 4 is based on the following formula to each structural parameters in the multiple structural parameters in the light Not normalized sensitivity in spectrum wave band is averaged, and using the corresponding serial mean of each wavelength points as the spectrum ripple Sensitivity after the systemization of section：

Wherein, Sensitivity_Sub-BandRepresent wave band λ_Sub-BandSystemization after sensitivity；Geodesic structure mould is treated in L expressions The number of structural parameters included by type.

2）3rd determining device 4 combines the respective systemization weight of the multiple structural parameters, to the multiple structural parameters In each not normalized sensitivity of the structural parameters in the spectral band carry out systemization and handle, determine the system of the spectral band Sensitivity after change.

As an example, the 3rd determining device 4 can be based on the following formula and combine the respective system of the multiple structural parameters Change weight, unite to not normalized sensitivity of each structural parameters in the spectral band in the multiple structural parameters Change is handled, and determines the sensitivity after the systemization of the spectral band：

For example, based on the structural model to be measured shown in Fig. 6, the second acquisition device 3 obtains structural parameters CD, SWA, HT in light Compose wave band λ_Sub-BandIn the range of not normalized sensitivity be respectively Sensitivity'_CD、Sensitivity'_SWA、 Sensitivity'_HT；3rd determining device 4 determines spectral band λ_Sub-BandSystemization after sensitivity be：

Wherein, w₁, w₂, w₃The respectively system weight of structural parameters CD, SWA, HT.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that it is any to each structural parameters in the multiple structural parameters in the spectral band Not normalized sensitivity carry out systemization processing, determine the realization method of the sensitivity after the systemization of the spectral band, should all Within the scope of the present invention.

4th determining device 5 is according to sensitive after the sensitivity after the systemization of the spectral band and full wave systemization Degree determines the ratio of the sensitivity after the systemization of the spectral band and the sensitivity after full wave systemization, and according to the ratio Value determines coefficient of the spectral band in spectrum simulation.

Wherein, the 4th determining device 5 determines the realization method and the 3rd determining device 4 of the sensitivity after full wave systemization Determine that the realization method of the sensitivity after the systemization of the spectral band filtered out is same or similar, details are not described herein.

Wherein, various ways can be used according to the sensitivity after the systemization of the spectral band and all-wave in the 4th determining device 5 The ratio of sensitivity after the systemization of section, to determine coefficient of the spectral band in spectrum simulation.

For example, the 4th determining device 5 can according to the sensitivity after the systemization of the spectral band with after full wave systemization The ratio of sensitivity determines coefficient of the spectral band in spectrum simulation based on predetermined formula, and such as the 4th determining device 5 can Based on the following formula, according to the sensitivity after the systemization of spectral band λ Sub-Band and all band λ_{Full Band}Systemization after spirit The ratio of sensitivity, to determine coefficient of the spectral band in spectrum simulation：

Wherein, Sensitivity_Sub-BandFor spectral band λ_Sub-Band∈(λ_a,λ_b) sensitivity； Sensitivity_{Full Band}For all band λ_{Full Band}∈(λ_Start,λ_End) sensitivity；υ_Sub-BandIt represents in spectrum simulation Spectral band λ_Sub-Band∈(λ_a,λ_b) coefficient；υ_TotalFor full wave fitting coefficient, 1 usually can be taken as；ξ represents sub-band Fitting weight adjustment factor, can manually be adjusted according to demand.

It should be noted that the above-mentioned examples are merely illustrative of the technical solutions of the present invention rather than the limit to the present invention System, it should be appreciated by those skilled in the art that sensitivity and full wave systemization after any systemization according to the spectral band Sensitivity afterwards determines the ratio of the sensitivity after the systemization of the spectral band and the sensitivity after full wave systemization, and root The realization method of coefficient of the spectral band in spectrum simulation is determined according to the ratio, should be included in the scope of the present invention It is interior.

It, can be with reference to the system weight of each structural parameters, to determine to filter out according to the wave band screening plant of the present embodiment One or more spectral bands systemization after sensitivity and sensitivity after full wave systemization between ratio, so as to really Fixed coefficient of the one or more spectral band when carrying out spectrum simulation so that can be to different wavelength regions in fitting Coefficient targetedly set, so as to greatly improve the Stability and veracity of OCD measurement results.

It should be noted that the present invention can be carried out in the assembly of software and/or software and hardware, for example, this hair Application-specific integrated circuit can be used in bright device（ASIC）Or any other is realized similar to hardware device.In one embodiment, The software program of the present invention can perform to realize steps described above or function by processor.Similarly, it is of the invention soft Part program（Including relevant data structure）It can be stored in computer readable recording medium storing program for performing, for example, RAM memory, magnetic Or CD-ROM driver or floppy disc and similar devices.In addition, hardware can be used to realize in some steps or function of the present invention, example Such as, as the circuit for coordinating to perform each step or function with processor.

It is obvious to a person skilled in the art that the invention is not restricted to the details of above-mentioned exemplary embodiment, Er Qie In the case of without departing substantially from spirit or essential attributes of the invention, the present invention can be realized in other specific forms.Therefore, no matter From the point of view of which point, the present embodiments are to be considered as illustrative and not restrictive, and the scope of the present invention is by appended power Profit requirement rather than above description limit, it is intended that all by what is fallen within the meaning and scope of the equivalent requirements of the claims Variation includes within the present invention.Any reference numeral in claim should not be considered as to the involved claim of limitation.This Outside, it is clear that one word of " comprising " is not excluded for other units or step, and odd number is not excluded for plural number.That is stated in system claims is multiple Unit or device can also be realized by a unit or device by software or hardware.The first, the second grade words are used for table Show title, and do not represent any particular order.

Claims (18)

1. a kind of be used for the method for screening wave band in OCD measurements, wherein, this method comprises the following steps：

A is for each structural parameters in multiple structural parameters of structural model to be measured, according to the variation by the structural parameters Caused by corresponding spectrally each wavelength points spectral signal offset, determine the structural parameters at each wavelength points Sensitivity；

B screens one or more spectral bands according to the sensitivity at each of which wavelength points respectively of the multiple structural parameters；

Wherein, this method further includes the following steps performed to a spectral band in one or more of spectral bands：

X is obtained according at each wavelength points of the spectral band, the not normalized sensitivity respectively of the multiple structural parameters Obtain each not normalized sensitivity of the structural parameters in the spectral band in the multiple structural parameters；

Y combines the respective systemization weight of the multiple structural parameters, to each structural parameters in the multiple structural parameters at this Not normalized sensitivity in spectral band carries out systemization processing, determines the sensitivity after the systemization of the spectral band；

Z determines the spectral band according to the sensitivity after the systemization of the spectral band and the sensitivity after full wave systemization Systemization after sensitivity and full wave systemization after sensitivity ratio, and the spectral band is determined according to the ratio Coefficient in spectrum simulation.

2. according to the method described in claim 1, wherein, the step b comprises the following steps：

B1 is according to the sensitivity at each of which wavelength points respectively of the multiple structural parameters, to all knots at each wavelength points The sensitivity of structure parameter carries out systemization processing, obtains the total sensitivity after systemization at each wavelength points；

B2 screens one or more of spectral bands according to the total sensitivity after systemization at each wavelength points.

3. according to the method described in claim 2, wherein, the step b1 comprises the following steps：

Place is normalized in each sensitivity of the structural parameters at each of which wavelength points in the multiple structural parameters by b11 Reason, obtain multiple structural parameters respectively at each of which wavelength points, sensitivity after normalization；

B12 carries out the sensitivity after having the normalization of structural parameters at each wavelength points systemization processing, obtains each wavelength Total sensitivity at point after systemization.

4. according to the method described in claim 3, wherein, the step b12 comprises the following steps：

- with reference to the respective systemization weight of the multiple structural parameters, the normalization to all structural parameters at each wavelength points Sensitivity afterwards carries out systemization processing, obtains the total sensitivity after systemization at each wavelength points.

5. according to the method described in claim 4, wherein, the systemization weight is determined based at least one of following：

Importance of the structural parameters in technology controlling and process corresponding to the-systemization weight；

User's attention rate of structural parameters corresponding to the-systemization weight.

6. the method according to any one of claim 2 to 5, wherein, the step b comprises the following steps：

- according to the total sensitivity after systemization at each wavelength points, determine that threshold value is screened in sensitivity；

Wherein, the step b2 comprises the following steps：

- according to the total sensitivity after systemization at each wavelength points, and with reference to sensitivity screening threshold value, screening described one A or multiple spectral bands.

7. the method according to any one of claims 1 to 5, wherein, this method is further comprising the steps of：

- each structural parameters in multiple structural parameters of geodesic structure model are treated, under given measurement pattern, the structure of floating Parameter obtains spectral signal offset of the structural parameters at its each wavelength points spectrally.

8. the method according to any one of claims 1 to 5, wherein, this method further includes following before the step a Step：

- according to the material and structural parameters for treating geodesic structure, establish the structural model to be measured.

9. the method according to any one of claims 1 to 5, wherein, the structural parameters include representing the knot to be measured The various parameters of the structure feature of structure model.

10. a kind of wave band screening plant for being used to screen wave band in OCD measurements, wherein, which includes following Device：

First determining device, for each structural parameters in multiple structural parameters for structural model to be measured, according to by this The variation of structural parameters and caused by corresponding spectrally each wavelength points spectral signal offset, determine the structural parameters in institute State the sensitivity at each wavelength points；

Screening plant, for according to the sensitivity at each of which wavelength points respectively of the multiple structural parameters, screening one or Multiple spectral bands；

Wherein, which further includes performs operation to a spectral band in one or more of spectral bands Following device：

Second acquisition device, for according to the multiple structural parameters respectively at each wavelength points of the spectral band, not Normalized sensitivity obtains not normalized spirit of each structural parameters in the spectral band in the multiple structural parameters Sensitivity；

3rd determining device, for combining the respective systemization weight of the multiple structural parameters, in the multiple structural parameters Each not normalized sensitivity of the structural parameters in the spectral band carries out systemization processing, determines the system of the spectral band Sensitivity afterwards；

4th determining device, for sensitive after the sensitivity after the systemization according to the spectral band and full wave systemization Degree determines the ratio of the sensitivity after the systemization of the spectral band and the sensitivity after full wave systemization, and according to the ratio Value determines coefficient of the spectral band in spectrum simulation.

11. wave band screening plant according to claim 10, wherein, the screening plant includes following device：

First acquisition device, for according to the sensitivity at each of which wavelength points respectively of the multiple structural parameters, to each The sensitivity of all structural parameters at wavelength points carries out systemization processing, obtains the total sensitivity after systemization at each wavelength points；

First sub- screening plant, for according to the total sensitivity after systemization at each wavelength points, screening one or more A spectral band.

12. wave band screening plant according to claim 11, wherein, first acquisition device includes following device：

First sub- acquisition device, for each structural parameters in the multiple structural parameters are sensitive at each of which wavelength points Degree is normalized, obtain multiple structural parameters respectively at each of which wavelength points, sensitivity after normalization；

Second sub- acquisition device, for there is the sensitivity after the normalization of structural parameters to carry out systemization place at each wavelength points Reason, obtains the total sensitivity after systemization at each wavelength points.

13. wave band screening plant according to claim 12, wherein, the second sub- acquisition device includes following device：

3rd sub- acquisition device, for combining the respective systemization weight of the multiple structural parameters, to the institute at each wavelength points There is the sensitivity after the normalization of structural parameters to carry out systemization processing, obtain described total sensitive after systemization at each wavelength points Degree.

14. wave band screening plant according to claim 13, wherein, the systemization weight is based at least one of following come really It is fixed：

Importance of the structural parameters in technology controlling and process corresponding to the-systemization weight；

User's attention rate of structural parameters corresponding to the-systemization weight.

15. the wave band screening plant according to any one of claim 11 to 14, wherein, the screening plant includes following Device：

Second determining device, for according to the total sensitivity after systemization at each wavelength points, determining that threshold value is screened in sensitivity；

Wherein, the described first sub- screening plant includes following device：

Second sub- screening plant, for according to the total sensitivity after systemization at each wavelength points, and with reference to the sensitivity Threshold value is screened, screens one or more of spectral bands.

16. the wave band screening plant according to any one of claim 10 to 14, wherein, which further includes Following device：

3rd acquisition device, for treating each structural parameters in multiple structural parameters of geodesic structure model, in given measurement Under pattern, the structural parameters are floated to obtain spectral signal offset of the structural parameters at its each wavelength points spectrally Amount.

17. the wave band screening plant according to any one of claim 10 to 14, wherein, which further includes The following device of operation is performed before first determining device：

Model foundation device, for according to the material and structural parameters for treating geodesic structure, establishing the structural model to be measured.

18. the wave band screening plant according to any one of claim 10 to 14, wherein, the structural parameters include representing The various parameters of the structure feature of the structural model to be measured.