CN104914684B - A kind of extreme Ultraviolet Lithography Source mask combined optimization method - Google Patents

Abstract

The present invention provides a kind of extreme Ultraviolet Lithography Source photomask optimization method, this method distinguishes application parameter and pixelation light source, and main body figure and secondary graphics are respectively configured to superposition of some single side sizes more than or equal to the basic module of predetermined threshold, optimization object function is configured to imaging fidelity function and light source and mask penalty function sum；This method is based on scalar imaging model afterwards, hybrid optimization is carried out to extreme Ultraviolet Lithography Source and mask graph using conjugate gradient method and improved conjugate gradient method, and ensure that the minimum spacing between main body figure and secondary graphics is more than or equal to predetermined threshold in each iteration, and correct mask graph after optimization terminates, the edge protuberance that removal cannot be manufactured simultaneously compensates mask shadow effect.This method can simultaneously compensate optical proximity effect in extreme ultraviolet lithography system, effects of spurious light, photoresist effect and mask shadow effect, and effectively improve the manufacturability of mask after optimization.

Description

A kind of extreme Ultraviolet Lithography Source-mask combined optimization method

Technical field

The present invention relates to a kind of extreme ultraviolet photolithographic (extreme ultraviolet lithography, abbreviation EUV) light Source-mask combined optimization method, belongs to photoetching resolution enhancing technical field.

Background technology

Photoetching technique is the core technology that large scale integrated circuit manufactures field.The etching system of current main flow is 193nm Argon fluoride (ArF) deep ultraviolet (deep ultraviolet lithography, abbreviation DUV) etching system, with photoetching skill Art node moves down into 22nm and following technology node, and being become using the EUV lithography of 13.5nm optical source wavelengths be most hopeful replacement One of technology of DUV photoetching.Because nearly all material has strong absorption to the light wave of 13.5nm or so wavelength, Therefore EUV lithography system must be using total-reflection type and the optical texture of non-doubly telecentric.Above-mentioned and other factors cause EUV Etching system has many imaging phenomenons different from DUV etching systems.Influence EUV lithography systemic resolution and image quality Factor have a lot, including：Optical proximity effect, effects of spurious light, photoresist effect and mask shadow effect.In order to improve The resolution ratio and image quality of EUV lithography system, it is necessary to which effective compensation is carried out to any of the above effect.

Light source-mask combined optimization technology (source mask optimization, abbreviation SMO) is a kind of important light Carve RET.It is by optimizing the shape of light source and the main graph (main feature, abbreviation MF) of mask And Sub-resolution assist features (sub-resolution assist feature, abbreviation around main body figure SRAF the electric-field intensity amplitude of the light of mask is incided in method), modulation, so as to improve the resolution ratio and figure of etching system Fidelity.By described previously, in order to improve the resolution ratio and anti-aliasing degree of EUV lithography system, EUV light source-mask joint is excellent Change technology is needed under conditions of compensation effects of spurious light, photoresist effect and mask shadow effect is considered, optimization light source form, Compensation optical proximity effect.

SMO technologies can be divided into application parameter source model and apply pixelation source model by source model used Two kinds.Because parametrization light source has a conventional geometry, therefore it by several parameters can determine net shape and have Manufacturability advantage high；And pixelation light source is by rasterizing profiles characteristic, it can greatly improve the optimization free degree, therefore should Anti-aliasing degree can be further improved with pixelation light source.

On the other hand, EUV lithography mask is by the reflecting layer using multi-layer film structure and the absorbed layer being attached on reflecting layer Constituted.In order to ensure and improving the manufacturability of mask, in optimization process, mask graph needs following four of satisfaction important Constraints：(1) the minimum dimension w of main body figure_MHave to be larger than equal to threshold epsilon_M, i.e. w_M≥ε_M；(2) mask auxiliary The minimum dimension w of figure_SHave to be larger than equal to threshold epsilon_S, i.e. w_S≥ε_S；(3) between main body figure and secondary graphics most Small distance w_DHave to be larger than equal to threshold epsilon_D, i.e. w_D≥ε_D；(4) do not allow the presence of any edge that cannot be manufactured in mask graph It is raised.If the height of edge protuberance is w_H, the both sides brachium of edge protuberance is respectively w_L1And w_L1, ε_HAnd ε_LIt is threshold value.When certain side Edge is raised to meet " w_H≤ε_H" and " w_L1Or w_L2≤ε_L", then this projection is called " edge protuberance that cannot be manufactured ".

In sum, present invention development it is a kind of based on parametrization source model and pixelation source model and meet mask can Manufacturing constraints, can compensate for the EUV of optical proximity effect, effects of spurious light, photoresist effect and mask shadow effect Light source-mask combined optimization method.

The content of the invention

It is excellent it is an object of the invention to provide the EUV light source based on parametrization light source or pixelation source model-mask joint Change method the, wherein light source-mask combined optimization method based on parametrization source model, builds light source parameters as Optimal Parameters Mould simultaneously finally determines to optimize the shape of light source by optimization；Light source based on pixelation source model-mask combined optimization method It is that the intensity of each light source point is optimized as optimization object.Photomask optimization part in the present invention is used based on module Main body graphical configuration is that some single side sizes are more than or equal to threshold epsilon by photomask optimization method, the method_MBasic module Mask secondary graphics are configured to some single side sizes more than or equal to threshold epsilon by superposition_SBasic module superposition.Therefore, mask Main graph can be configured to the convolution of main graph basic module and the coefficient matrix for characterizing main graph basic module position；Cover Mould secondary graphics can be configured to the convolution of secondary graphics basic module and the coefficient matrix for characterizing secondary graphics basic module position. Whole mask graph is represented by main graph and secondary graphics sum.The method is based on scalar imaging model afterwards, using altogether Yoke gradient method (referred to as " method 1 ") synchronizes optimization to two kinds of the light source figures of form, main body figure and secondary graphics, And the mask after optimization is further corrected, so as to optimize light source figure, while comprehensive compensation optical proximity effect, miscellaneous Astigmatism effect, photoresist effect and mask shadow effect.In each Optimized Iterative, the method ensures main body figure and auxiliary The minimum range of figure is helped to be more than or equal to threshold epsilon_D。

Realize that technical scheme is as follows：

A kind of EUV lithography light source-mask combined optimization method, concretely comprises the following steps：

Step 101, for parametrization light source, object function D is configured to D=F+ γ_dR_d, wherein F is imaging fidelity letter Number, R_dIt is mask penalty function, γ_dIt is the weight factor of penalty function；

For pixelation light source, object function D is configured to D=F+ γ_dR_d+γ_SR_S, wherein γ_SFor light source penalty term is weighed Repeated factor, light source penalty termSig () represents sigmoid function；

Step 102, when light source for parametrization light source when, according to primary light source graphics calculations initialize Ω_σ, and based on initial The Ω of change_σCalculating target function D is relative to Ω_σDerivativeBy Ω_σOptimization direction be initialized as

Wherein, b_σIt is default slope, σ_minAnd σ_maxIt is the minimum, maximum to be got of light source parameters σ；

When light source is pixelation light source, initialization Ω is calculated according to primary light source figure J_s, and the Ω based on initialization_s Calculating target function D is relative to Ω_sGradient matrixAnd by Ω_sOptimization direction be initialized as

Based on initial mask main graphWith initial mask secondary graphicsCalculating target function D relative to Main graph coefficient matrixGradient matrixAnd object function D is relative to secondary graphics coefficient matrixLadder Degree matrixAnd by main graph coefficient matrixOptimization direction matrixIt is initialized as： By secondary graphics coefficient matrixOptimization direction matrixIt is initialized as

Step 103, when light source be parametrization light source when, permanent mask figure, based on current Ω_σWithUsing conjugation Gradient method (referred to as " method 1 "), to Ω_σCarry out 1 renewal；

When light source of the light source for pixelation, permanent mask figure, based on current Ω_sWithUsing conjugate gradient method (letter Claim " method 1 "), to Ω_s1 renewal is carried out, and in the updated by the point intensity level zero setting of pupil outer light source；

Step 104, calculating current light source figure, and calculate current light source figure and binary mask pattern M_bIt is corresponding into As fidelity function F, when F is less than predetermined threshold ε_F, into step 111, as renewal light source parameters Ω_σOr Ω_sNumber of times reach it is pre- When determining higher limit, into step 105, otherwise return to step 103；

Step 105, the main graph coefficient matrix based on initializationWith optimization direction matrixUsing conjugate gradient Method (referred to as " method 1 ") is to main graph coefficient matrix Θ_MPixel value carry out 1 renewal, and in the updated by Θ_MIt is all Pixel value is limited in the range of [0,1], wherein the pixel value more than 1 is set as 1, the pixel value less than 0 is set as 0, between [0, 1] pixel value in the range of keeps constant；

Step 106, calculating main graph binary coefficient matrix Θ_Mb=Γ { Θ_M-0.5}；By the main body figure of N × N It is configured toCalculate main body figure M_b,mainIn polygon number, if current calculate The polygon number for going out is compared with last time circulation and is not changed in, then into step 108, otherwise into step 107；

Step 107, by main graph coefficient matrix Θ_MValue revert to value before this is recycled into step 105, base In the main graph coefficient matrix of initializationWith optimization direction matrixAnd it is (referred to as " square using improved conjugate gradient method Method 2 ") and endless form to the coefficient matrix Θ corresponding to main body pattern edge_MPixel value be iterated renewal, until Untill the edge of current topic figure no longer changes；And every time in iteration by matrix Θ_MAll pixels value be limited to [0,1] model In enclosing, wherein the pixel value more than 1 is set as 1, the pixel value less than 0 is set as 0, and the pixel value in the range of [0,1] is protected Hold constant；And calculate main graph binary coefficient matrix Θ_Mb=Γ { Θ_M-0.5}。

Step 108, the secondary graphics coefficient matrix based on initializationOptimization direction matrixUsing conjugate gradient method (referred to as " method 1 ") is to secondary graphics coefficient matrix Θ_SPixel value carry out 1 renewal, and in the updated by all pixels value It is limited in the range of [0,1], wherein the pixel value more than 1 is set as 1, the pixel value less than 0 is set as 0, between [0,1] scope Interior pixel value keeps constant；Afterwards, in order to ensure the minimum range between main graph and secondary graphics is more than or equal to threshold value ε_D, by Θ_SIt is modified to：

Calculate secondary graphics binary coefficient matrix Θ_Sb=Γ { Θ_S-0.5}。

Step 109, when light source be parametrization light source when, based on current Ω_σWithUsing conjugate gradient method (referred to as " method 1 "), to Ω_σCarry out 1 renewal；

When light source of the light source for pixelation, based on current Ω_sWithUsing conjugate gradient method (referred to as " method 1 "), To Ω_s1 renewal is carried out, and will in the updated by the point intensity level zero setting of pupil outer light source；

Step 110, calculating current light source figure and binary mask pattern M_b, and calculate current light source figure and binary is covered Mould figure M_bCorresponding imaging fidelity function F；When F is less than predetermined threshold ε_FOr circulation step 105 is to step 109 pair light When the number of times that source parameter and mask parameters are iterated renewal reaches predetermined upper limit value, into step 111, otherwise return to step 105；

Step 111, terminate optimization, and by current light source figure and binary mask pattern M_bIt is defined as by the light after optimization Source figure and mask graph, and correct the edge protuberance that cannot be manufactured in the mask graph.

Step 112, the mask graph obtained by step 111 is masked shadow effect compensation, obtain final mask Optimum results.

Imaging fidelity function F of the present invention is defined as：It is imaged in targeted graphical photoresist corresponding with current mask The quadratic sum of the Euler's distance between the weighted sum of the difference square of each pixel.

The calculation procedure being imaged in the corresponding photoresist of current mask figure of the present invention is：

Step 201, mask graph M grids are turned into N × N number of subregion.

Step 202, surface of light source is tiled into by multiple spot lights according to the shape of partially coherent light source, uses each grid zone Domain center point coordinate (x_s,y_s) represent spot light coordinate corresponding to the grid region.

Step 203, for single spot light, using its coordinate (x_s,y_s) obtain corresponding wafer position during the spot light On aerial imageWhereinIt is corresponding to spot light (x_s,y_s) light Etching system point spread function,It is corresponding to spot light (x_s,y_s) mask diffraction matrices, symbol ⊙ representing matrixs Or the corresponding element multiplication operation of vector,Represent the complex number space of N × N.

Step 204, judge whether to have calculated aerial image on all spot lights correspondence wafer positions, if so, then entering Enter step 205, otherwise return to step 203.

Step 205, according to Abbe (Abbe) method, aerial image I (x corresponding to each spot light_s,y_s) be overlapped, obtain During partially coherent light source lighting, the aerial image on wafer position：

WhereinIt is normalization factor.

Step 206, in view of the veiling glare having in EUV lithography system to the influence caused by aerial image, by step Aerial image I obtained in 205₀It is modified toWherein TIS is overall dispersion factor, PSF_f It is a matrix of N × N, represents veiling glare point spread function, PSF_fIt is represented by：

WhereinIt is the position coordinates on chip, n_fIt is spectral index, r_min Represent the compass between low frequency phase error and high-frequency phase error.

Step 207, based on EUV lithography glue approximate model, be calculated as being imaged in the corresponding photoresist of mask graph：Wherein It is PSF_rVariance, t_rFor Photoresist threshold value.

Using conjugate gradient method to Ω in step 103 of the present invention, 105,108 and 109_σAnd matrix Ω_s、Θ_MΘ_S Pixel value carry out 1 time renewal detailed process for (due to following steps 401 to step 403 simultaneously be applied to Ω_σAnd matrix Ω_s、Θ_MAnd Θ_S, therefore symbolization X represents Ω in step 401 to step 403_σ、Ω_s、Θ_MOr Θ_S, symbolization Θ generations Table Θ_MOr Θ_S, symbolization P represents P_S、P_SOr P_M, i.e. the corresponding optimization directioin parameter P of parameter is updated needed for P representatives_SOr matrix P_SAnd P_M)

Step 401, renewal coefficient matrix X are：X^k+1=X^k+s×P^k, wherein, s is optimization step-length set in advance,It is optimization direction matrix；

If step 402, now renewal light source parameters Ω_σOr Ω_s, then this step to 403 is skipped；If now more new light sources are joined Number Θ_MOr Θ_S, then following steps are performed：

The pixel value of Θ is limited in [0,1] interval, i.e.,：

Step 403, calculating parameter β areWhereinRepresent to matrix modulus and squared.

Step 404, renewal optimization direction matrix P are：

Using improved conjugate gradient method and endless form to corresponding to main body figure in step 107 of the present invention The coefficient matrix Θ at edge_MPixel value be iterated the detailed process of renewal and be：

Step 501, renewal binary coefficient matrix are Θ_Mb=Γ { Θ_M- 0.5 }, updating main body figure isCalculate M_b,mainProfileFor：

Meanwhile, current coefficient matrix is designated as Θ '_M；

Step 502, renewal coefficient matrix Θ_MFor：Wherein s is optimization set in advance Step-length, updating optimization direction matrix is：

Step 503, by Θ_MPixel value be limited in [0,1] it is interval in, i.e.,：

Step 504, according to current Θ_MCalculate Θ_Mb=Γ { Θ_M- 0.5 }, update And update M_b,mainProfileFor：

If nowBefore being updated with step 504Compared to then return to step 502 are varied from, otherwise into step 505；

Step 505, calculating parameter β_MFor

Step 506, will optimization direction matrix P be updated to：

In step 111 of the present invention, binary mask pattern M is corrected_bIn the edge protuberance that cannot be manufactured specific step Suddenly it is：

Step 601, the position for calculating all concave crown points in current binary mask pattern, wherein concave crown point are defined as mask artwork Shape is internally formed 270 ° of summits at angle；

All concave crown points in step 602, traversal binary mask pattern, and correct traversal it is run into first without legal system The edge protuberance made；Specially：It is convex to this edge if the corresponding edge protuberance of concave crown point is the edge protuberance that cannot be manufactured Rising carries out two kinds of amendments, that is, fill and scabble, and respectively obtains two revised binary mask patterns：M′_bWith M "_b；Using scalar Imaging model calculates correspondence M ' respectively_bWith M "_bImaging fidelity function F ' and F ".If F ' ＜ F " if by current binary mask figure Shape is updated to M '_b, current binary mask pattern is otherwise updated to M "_b；The wherein described edge protuberance that cannot manufacture is：If side The raised height of edge is w_H, the both sides brachium of edge protuberance is respectively w_L1And w_L1, ε_HAnd ε_LIt is threshold value；When certain edge protuberance meets w_H≤ε_HAnd w_L1Or w_L2≤ε_L, then this projection is called the edge protuberance that cannot be manufactured；

Step 603, judge whether the edge protuberance that cannot manufacture is corrected in step 602, if then entering Step 601, otherwise, shows do not existed the edge protuberance that cannot be manufactured in current binary mask image, now into step 112。

The tool of shadow effect compensation is masked in step 112 of the present invention to the mask graph obtained by step 111 Body step is：

Step 701, coordinate system is set in the exposure field of EUV lithography machine annular sector, wherein origin is in exposure field center Position, y-axis positive direction points to the center of circle of annular sector exposure field, and x-axis is vertical with y-axis, and is rotated by 90 ° to y-axis from x-axis positive direction Positive direction is for counterclockwise；

Step 702, for certain pattern edge on mask, calculate the corresponding parameter alpha in the edge_s, i.e.,：Wherein α '_sIt is the azimuth at the mask graph edge, W is The width of annular sector exposure field, F is the angular aperture of annular sector exposure field；X is the exposure field position residing for mask graph edge The x-axis coordinate put；

Step 703, calculate the corresponding mask shade width B in the mask graph edge_s, work as α_sAt >=90 °,Work as α_sDuring 90 ° of ＜,Wherein B_{max_near}It is nearer apart from light source The maximum shade width of pattern edge, B_{max_far}It is the maximum shade width of the pattern edge apart from light source farther out, n_sIt is modifying factor Son, parameter B_{max_near}、B_{max_far}And n_sCan be drawn by data fitting；

Step 704, by the outside extension width B in the mask graph edge_s；

Step 705, judge whether to have have modified all mask graph edges, if so, then using current mask figure as Compensate for the mask graph after mask shadow effect, otherwise return to step 702.

Beneficial effect

Firstth, it is excellent the invention provides the parametrization light source and the light source of pixelation light source-mask joint for EUV light source Change method.The present invention can not only be directed to actual demand and provide the parametrization light source or the more preferable picture of exposure effect being easily manufactured Elementization light source, the optical proximity effect in compensation EUV lithography system, can also simultaneously compensate effects of spurious light, photoresist effect With mask shadow effect.

Secondth, main body figure and secondary graphics are configured to single side size more than or equal to predetermined threshold by the present invention The convolution of basic module and coefficient matrix, therefore during photomask optimization, can automatically ensure main body figure and auxiliary Any portion of minimum dimension is all higher than or equal to predetermined threshold in figure.

3rd, minimum spacing of the present invention in each iteration all between control main body figure and secondary graphics is more than Or equal to predetermined threshold, so as to while algorithmic statement characteristic is ensured, it is ensured that the spacing of main body figure and secondary graphics Meet manufacturability constraints.

4th, the present invention is modified to the edge protuberance that cannot be manufactured in mask graph, further increases mask Manufacturability.

Brief description of the drawings

Fig. 1 is EUV lithography light source-mask combined optimization method flow chart in the present invention.

Fig. 2 is the flow chart of conjugate gradient method (referred to as " method 1 ") in Fig. 1.

Fig. 3 is the flow chart of improved conjugate gradient method (referred to as " method 2 ") in Fig. 1.

Fig. 4 is edge protuberance and two kinds of schematic diagrames of modification method to " edge protuberance that cannot be manufactured ".

Fig. 5 is the schematic diagram of imaging in primary light source, mask and its corresponding photoresist.

Fig. 6 is the schematic diagram of imaging in the light source based on method of the present invention optimization, mask and its corresponding photoresist.

Specific embodiment

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

Principle of the invention：When being imaged identical with targeted graphical or approximate in the photoresist of EUV lithography system, then print Figure on chip meets resolution requirement, and with anti-aliasing degree very high.As shown in figure 1, the present invention is based on basic The application parameter of module or the EUV light source of pixelation light source-mask combined optimization method, concretely comprise the following steps：

Step 101, when light source is for parametrization light source (the present embodiment is illustrated by taking annular initialization light source as an example), this When light source parameters σ include external coherence system factor sigma_outWith ring width σ_w, initialize the external coherence system factor sigma of light source figure_outWith ring width σ_w, by This, light source J can be modeled according to equation below：

Wherein,It is light source center point to light source point (x_s,y_s) distance.Light source figure J as described above It is a binary matrix, it is impossible to its derivation, therefore, in order to be applied to gradient algorithm to parameterize light source graphics-optimized, use The above-mentioned light source of arch function pair that can be led carries out approximately as described below：

Wherein, b_sIt is the obliquity factor in parameter preset source model formula.σ will be represented using σ in the present invention_out And σ_w.Partial coherence factor maximum is 1, therefore σ_out∈ (0,1], σ_w∈(0,σ_out].Assuming that σ ∈ [σ_min,σ_max], in order to incite somebody to action Conditional optimization problem is converted into unconfined problem, using following Parameter Switch：

Wherein b_σIt is to preset slope, and Ω_σ∈ (- ∞, ∞) is the conversion parameter of σ, is represented by：

Above-mentioned parameter source model can also expand to the light source of other specification, such as level Four illumination etc..

When the light source is pixelation light source, light source figure is rasterized into being N_s×N_sPixel, and each pixel Represent corresponding light source point intensity.Different from parametrization light source, pixelation light source pixel point value can be floated in the range of [0,1] Dynamic, all of light source pixel point can be optimized with the SMO algorithms for being proposed.Therefore, light source J can be modeled as：

Wherein, Ω_sIt is N_s×N_sReal number matrix, its value can float in the range of (- ∞, ∞)；

Initialization size is the targeted graphical of N × NWhereinRepresent the real number space of N × N；

For the SMO of parametrization light source, object function D is configured to D=F+ γ_dR_d, wherein F is imaging fidelity function, fixed Justice for the difference square for being imaged each pixel in targeted graphical and the corresponding photoresist of current mask weighted sum between Euler's distance square With that is,WhereinIt is the weighting matrix of N × N, Π (m, n) is the unit of Π Element value,It is the pixel value of targeted graphical, Z (m, n) represents corresponding using scalar imaging model calculating current mask figure The pixel value being imaged in photoresist；R_dIt is mask penalty function, is defined as γ_dIt is the weight factor of penalty function, n_r、n_aThe respectively electric-field intensity reflectance factor in mask reflecting layer and absorbed layer,It is the mask graph of N × N, M (m, n) is the pixel value of M；

For pixelation light source, object function D is configured to D=F+ γ_dR_d+γ_SR_S, wherein F, R_d、γ_dIt is same as above, γ_SIt is light source penalty term weight factor, light source penalty termSig (x, tr)=1/ { 1+exp [- a (x-tr)] }, tr=0 is threshold value, and a=25 is slope.

The calculation procedure of imaging is in the corresponding photoresist of current mask figure in step 101 of the present invention：

Step 201, mask graph M grids are turned into N × N number of subregion.

Step 202, surface of light source is tiled into by multiple spot lights according to the shape of partially coherent light source, uses each grid zone Domain center point coordinate (x_s,y_s) represent spot light coordinate corresponding to the grid region.

Step 203, for single spot light, using its coordinate (x_s,y_s) obtain corresponding wafer position during the spot light On aerial imageWhereinIt is corresponding to spot light (x_s,y_s) light Etching system point spread function,It is corresponding to spot light (x_s,y_s) mask diffraction matrices, symbol ⊙ representing matrixs Or the corresponding element multiplication operation of vector,Represent the complex number space of N × N.

Step 204, judge whether to have calculated aerial image on all spot lights correspondence wafer positions, if so, then entering Enter step 205, otherwise return to step 203.

Step 205, according to Abbe (Abbe) method, aerial image I (x corresponding to each spot light_s,y_s) be overlapped, obtain During partially coherent light source lighting, the aerial image on wafer position：

WhereinIt is normalization factor.

Step 206, in view of the veiling glare having in EUV lithography system to the influence caused by aerial image, by step Aerial image I obtained in 205₀It is modified toWherein TIS is overall dispersion factor, PSF_f It is a matrix of N × N, represents veiling glare point spread function, PSF_fIt is represented by：

WhereinIt is the position coordinates on chip, n_fIt is spectral index, r_min Represent the compass between low frequency phase error and high-frequency phase error.

Step 207, based on EUV lithography glue approximate model, be calculated as being imaged in the corresponding photoresist of mask graph：Wherein It is PSF_rVariance, t_r It is photoresist threshold value.

Step 102, when light source for parametrization light source when, according to primary light source graphics calculations initialize Ω_σ, and based on initial The Ω of change_σCalculating target function D is relative to Ω_σJacobian matrixBy Ω_σOptimization direction be initialized as

Wherein

And

Therefore

Wherein

Again

WhereinWithAs described above.

When light source is pixelation light source, initialization Ω is calculated according to primary light source figure J_s, and the Ω based on initialization_s Calculating target function D is relative to Ω_sGradient matrixBy Ω_sOptimization direction be initialized as

Due toTherefore, object function is to Ω_sGradient be：

Herein,It is anti-aliasing degree to Ω_sGradient, can be calculated as below：

Wherein, 1_N×1It is vector that element value is all one, and：

In above formulaIn addition：

Therefore, can obtain：

Light source penalty term is to Ω_sGradient be

By the main graph coefficient matrix Θ of N × N_MIt is initialized as：

Wherein, m, n=1,2 ..., N；P, q=1,2 ..., N_WM；W_MIt is N_WM×N_WMThe basic mould of main body figure Block, its pixel value is 0 or 1, and its figure can be more than threshold epsilon for any single side size_MPolygon.W_M(p,q) WithRespectivelyW_MWithPixel value, symbolRepresent convolution algorithm；Calculate initial subject Figure is：Wherein Γ (x) is hard decision function, if i.e. x >=0, Γ (x)=1 is no Then Γ (x)=0；

By the secondary graphics coefficient matrix Θ of N × N_SIt is initialized as：

WhereinForPixel value, ε_seed≥ε_D+pixel_M×N_WS/ 2, pixel_MIt is the pixel in mask plane Single side size, N_WSIt is the single side size of mask secondary graphics basic module；Calculating initial secondary graphics is：Wherein W_SIt is N_WS×N_WSMask secondary graphics basic module.

Calculating target function D is relative to main graph coefficient matrixGradient matrixAnd object function D phases For secondary graphics coefficient matrixGradient matrixAnd by main graph coefficient matrixOptimization direction matrixIt is initialized as：By secondary graphics coefficient matrixOptimization direction matrixIt is initialized as

Object function D is relative to main graph coefficient matrix Θ_MGradient matrix be：Object function D is relative to Θ_MIn it is every The matrix that the partial derivative of one element is constituted.In the present invention, object function is for main graph coefficient matrix Θ_MGradient square Battle arrayCan be calculated as：

Wherein

In above formulaSigmoid function is represented bya Represent the gradient of sigmoid function, t_rThe threshold value of sigmoid function is represented,Represent matrix W_MRespectively overturn along horizontally and vertically direction 180 °,

Wherein^*Expression takes conjugate operation,δ is impulse function.On the other hand,

Wherein

Object function D is relative to secondary graphics coefficient matrix Θ_SGradient matrix be：Object function D is relative to Θ_SIn it is every The matrix that the partial derivative of one element is constituted.In the present invention, object function is for secondary graphics coefficient matrix Θ_SGradient square Battle arrayCan be calculated as：

Wherein

Step 103, when light source be parametrization light source when, permanent mask figure, based on current Ω_σWithTo use Conjugate gradient method (referred to as " method 1 "), to Ω_σCarry out 1 renewal.

When light source of the light source for pixelation, permanent mask figure, based on current Ω_sWithUsing conjugate gradient method (referred to as " method 1 "), to Ω_s1 renewal is carried out, and in the updated by the point intensity level zero setting of pupil outer light source.

Step 104, calculating current light source figure, and calculate current light source figure and binary mask pattern M_bIt is corresponding into As fidelity function F, when F is less than predetermined threshold ε_F, into step 111, as renewal light source parameters Ω_σOr Ω_sNumber of times reach it is pre- When determining higher limit, into step 105, otherwise return to step 103.

Step 105, the main graph coefficient matrix based on initializationWith optimization direction matrixUsing conjugate gradient Method (referred to as " method 1 ") is to main graph coefficient matrix Θ_MPixel value carry out 1 renewal, and in the updated by Θ_MIt is all Pixel value is limited in the range of [0,1], wherein the pixel value more than 1 is set as 1, the pixel value less than 0 is set as 0, between [0, 1] pixel value in the range of keeps constant.

As shown in Fig. 2 using conjugate gradient method (referred to as " method 1 ") in step 103 of the present invention, 105,108 and 109 To Ω_σ(for the ring illumination light source of this example, Ω_σIncludingWithAnd matrix Ω_s、Θ_MAnd Θ_SPixel value carry out 1 detailed process of renewal is for (because following steps 401 to step 403 are applied to simultaneouslyWithAnd matrix Ω_s、 Θ_MAnd Θ_S, therefore symbolization X is represented in step 401 to step 403Ω_s、Θ_MOr Θ_S, symbolization Θ represents Θ_MOr Θ_S, symbolization P represents P_S、P_SAnd P_M)：

Step 401, renewal coefficient matrix X are：X^k+1=X^k+s×P^k, wherein, s is optimization step-length set in advance,It is optimization direction matrix.

If step 402, now renewal light source parameters Ω_σOr Ω_s, then this step to 403 is skipped；If now more new light sources are joined Number Θ_MOr Θ_S, then following steps are performed：

The pixel value of Θ is limited in [0,1] interval, i.e.,：

Step 403, calculating parameter β areWhereinRepresent to matrix modulus and squared.

Step 404, renewal optimization direction matrix P are：

Step 106, calculating main graph binary coefficient matrix Θ_Mb=Γ { Θ_M-0.5}；By the main body figure of N × N It is configured toCalculate main body figure M_b,mainIn polygon number, if current calculate The polygon number for going out is compared with last time circulation and is not changed in, then into step 108, otherwise into step 107.

Step 107, by main graph coefficient matrix Θ_MValue revert to value before this is recycled into step 105, base In the main graph coefficient matrix of initializationWith optimization direction matrixAnd it is (referred to as " square using improved conjugate gradient method Method 2 ") and endless form to the coefficient matrix Θ corresponding to main body pattern edge_MPixel value be iterated renewal, until Untill the edge of current topic figure no longer changes；And every time in iteration by matrix Θ_MAll pixels value be limited to [0,1] model In enclosing, wherein the pixel value more than 1 is set as 1, the pixel value less than 0 is set as 0, and the pixel value in the range of [0,1] is protected Hold constant；And calculate main graph binary coefficient matrix Θ_Mb=Γ { Θ_M-0.5}。

As shown in figure 3, using improved conjugate gradient method (referred to as " method 2 ") and circulation in step 107 of the present invention Mode is to the coefficient matrix Θ corresponding to main body pattern edge_MPixel value be iterated the detailed process of renewal and be：

Step 501, renewal binary coefficient matrix are Θ_Mb=Γ { Θ_M- 0.5 }, updating main body figure isCalculate M_b,mainProfileFor：

Meanwhile, current coefficient matrix is designated as Θ '_M。

Step 502, renewal coefficient matrix Θ_MFor：Wherein s is optimization set in advance Step-length, updating optimization direction matrix is：

Step 503, by Θ_MPixel value be limited in [0,1] it is interval in, i.e.,：

Step 504, according to current Θ_MCalculate Θ_Mb=Γ { Θ_M- 0.5 }, update And update M_bmainProfileFor：

If nowBefore being updated with step 504Compared to then return to step 502 are varied from, otherwise into step 505；

Step 505, calculating parameter β are

Step 506, will optimization direction matrix P be updated to：

Step 108, the secondary graphics coefficient matrix based on initializationOptimization direction matrixUsing conjugate gradient method (referred to as " method 1 ") is to secondary graphics coefficient matrix Θ_SPixel value carry out 1 renewal, and in the updated by all pixels value It is limited in the range of [0,1], wherein the pixel value more than 1 is set as 1, the pixel value less than 0 is set as 0, between [0,1] scope Interior pixel value keeps constant；Afterwards, in order to ensure the minimum range between main graph and secondary graphics is more than or equal to threshold value ε_D, by Θ_SIt is modified to：

Calculate secondary graphics binary coefficient matrix Θ_Sb=Γ { Θ_S-0.5}。

Step 109, when light source be parametrization light source when, permanent mask figure, based on current Ω_σWithTo use Conjugate gradient method (referred to as " method 1 "), to Ω_σCarry out 1 renewal.

When light source of the light source for pixelation, permanent mask figure, based on current Ω_sWithUsing conjugate gradient method (referred to as " method 1 "), to Ω_s1 renewal is carried out, and will in the updated by the point intensity level zero setting of pupil outer light source.

Step 110, calculating current light source figure and binary mask patternAnd calculate current light source figure and binary mask Figure M_bCorresponding imaging fidelity function F；When F is less than predetermined threshold ε_FOr renewal X (in light source optimization is parameterized, X RepresentWithIn pixelation light source optimization, X represents Ω_s；In photomask optimization, X represents Θ_MAnd Θ_S) number of times reach During to predetermined upper limit value, into step 111, otherwise return to step 105, i.e., according to the mode of step 105 to 110 to mask-light Source is updated again.

Step 111, terminate optimization, and by current light source figure and binary mask pattern M_bIt is defined as by the light after optimization Source figure and mask graph, and correct the edge protuberance that cannot be manufactured in the mask graph.

In step 111 of the present invention, binary mask pattern M is corrected_bIn the edge protuberance that cannot be manufactured specific step Suddenly it is：

Step 601, the position for calculating all concave crown points in current binary mask pattern, wherein concave crown point are defined as mask artwork Shape is internally formed 270 ° of summits at angle.

All concave crown points in step 602, traversal binary mask pattern, and correct traversal it is run into first without legal system The edge protuberance made；Specially：It is convex to this edge if the corresponding edge protuberance of concave crown point is the edge protuberance that cannot be manufactured Rising carries out two kinds of amendments, i.e., filling is (as shown in 4001 dotted lines in Fig. 4) and scabbles (as shown in 4002 imaginary point lines in Fig. 4), respectively Obtain two revised binary mask patterns：M′_bWith M "_b；Correspondence M ' is calculated respectively using scalar imaging model_bWith M "_bInto As fidelity function F ' and F ".If F ' ＜ F " if current binary mask pattern is updated to M '_b, otherwise by current binary mask figure Shape is updated to M "_b；The wherein described edge protuberance that cannot manufacture is：As shown in figure 4, the height for setting edge protuberance is w_H, edge is convex The both sides brachium for rising is respectively w_L1And w_L1, ε_HAnd ε_LIt is threshold value；When certain edge protuberance meets " w_H≤ε_H" and " w_L1Or w_L2≤ε_L", Then this projection is called " edge protuberance that cannot be manufactured ".

Step 603, judge whether the edge protuberance that cannot manufacture is corrected in step 602, if then entering Step 601, otherwise, shows do not existed the edge protuberance that cannot be manufactured in current binary mask image, now into step 109。

Step 112, the mask graph obtained by step 111 is masked shadow effect compensation, obtain final mask Optimum results.

The tool of shadow effect compensation is masked in step 112 of the present invention to the mask graph obtained by step 111 Body step is：

Step 701, coordinate system is set in the exposure field of EUV lithography machine annular sector, wherein origin is in exposure field center Position, y-axis positive direction points to the center of circle of annular sector exposure field, and x-axis is vertical with y-axis, and is rotated by 90 ° to y-axis from x-axis positive direction Positive direction is for counterclockwise.

Step 702, for certain pattern edge on mask, calculate the corresponding parameter alpha in the edge_s, i.e.,：Wherein α '_sIt is the azimuth at the mask graph edge, W is The width of annular sector exposure field, F is the angular aperture of annular sector exposure field；X is the exposure field position residing for mask graph edge The x-axis coordinate put.

Step 703, calculate the corresponding mask shade width B in the mask graph edge_s, work as α_sAt >=90 °,Work as α_sDuring 90 ° of ＜,Wherein B_{max_near}It is nearer apart from light source The maximum shade width of pattern edge, B_{max_far}It is the maximum shade width of the pattern edge apart from light source farther out, n_sIt is modifying factor Son, parameter B_{max_near}、B_{max_far}And n_sCan be drawn by data fitting.

Step 704, by the outside extension width B in the mask graph edge_s。

Step 705, judge whether to have have modified all mask graph edges, if so, then using current mask figure as Compensate for the mask graph after mask shadow effect, otherwise return to step 702.

Embodiment of the invention：

Fig. 5 is the schematic diagram of imaging in initial EUV light source, mask and its corresponding photoresist, and its critical size is 16nm. 501 is light source figure；502 is targeted graphical, is also initial mask figure, and wherein white portion represents the reflection of multi-layer film structure Layer segment, black region is represented and absorbs layer segment；503 be using 501 as light source, 502 as mask after, EUV lithography system Photoresist in be imaged, image error is 6812, and edge dislocation error is 6.28nm, and wherein image error is defined as in photoresist The sum of all pixels that imaging is covered with targeted graphical distinct regions, edge dislocation error is defined as being imaged edge everywhere in photoresist The average value of (removing corner) relative to the side-play amount at targeted graphical edge.

Fig. 6 is the schematic diagram of imaging in the EUV mask and its corresponding photoresist optimized using the method for the present invention.601 It is the parametrization light source figure optimized using the method for the invention；602 is the mask artwork optimized using the method for the invention Shape；603 is, as light source, after 602 as mask, to be imaged in the photoresist of EUV lithography system using 601, and image error is 1429, edge dislocation error is 1.19nm.604 is the pixelation light source figure optimized using the method for the invention；605 is to adopt The mask graph optimized with the method for the invention；606 be using 604 as light source, after 605 as mask, EUV lithography system Photoresist in be imaged, image error is 1162, edge dislocation error be 0.85nm.

Comparison diagram 5 and Fig. 6 understand that the method for the invention can simultaneously compensate the optical adjacent effect in EUV lithography system Should, effects of spurious light, photoresist effect and mask shadow effect, so as to improve the image quality of EUV lithography system, in optimization light The automatic mask graph ensured after optimization meets the mask manufacturability restrictive condition that the present invention is previously mentioned while source.

Although combining Description of Drawings specific embodiment of the invention, it will be apparent to those skilled in the art that Under the premise without departing from the principles of the invention, some deformations, replacement can also be made and is improved, these also should be regarded as belonging to this hair Bright protection domain.

Claims (7)

1. a kind of EUV lithography light source-mask combined optimization method, it is characterised in that concretely comprise the following steps：

Step 101, for parametrization light source, object function D is configured to D=F+ γ_dR_d, wherein F is imaging fidelity function, R_dIt is mask penalty function, γ_dIt is the weight factor of penalty function；

For pixelation light source, object function D is configured to D=F+ γ_dR_d+γ_SR_S, wherein γ_SFor light source penalty term weight because Son, light source penalty termSig () represents sigmoid function, (x_s,y_s) it is the coordinate of spot light, J(x_s,y_s) it is spot light (x_s,y_s) light source figure；

Step 102, when light source for parametrization light source when, according to primary light source graphics calculations initialize Ω_σ, and based on initialization Ω_σCalculating target function D is relative to Ω_σJacobian matrixBy Ω_σOptimization direction be initialized as

${\mathrm{\Ω}}_{\mathrm{\σ}}=-\frac{1}{b_{\mathrm{\σ}}}\·ln(\frac{{\mathrm{\σ}}_{max}-{\mathrm{\σ}}_{\min }}{\mathrm{\σ}-{\mathrm{\σ}}_{\min }}-1)$

Wherein, b_σIt is default slope, σ_minAnd σ_maxIt is the minimum, maximum to be got of light source parameters σ；

When light source is pixelation light source, initialization Ω is calculated according to primary light source figure J_s, and the Ω based on initialization_sCalculate Object function D is relative to Ω_sGradient matrixAnd by Ω_sOptimization direction be initialized as

$J=f\left({\mathrm{\Ω}}_s\right)=\frac{1+{\mathrm{cos\Ω}}_s}{2},$

Based on initial mask main graphWith initial mask secondary graphicsCalculating target function D is relative to main body figure Shape coefficient matrixGradient matrixAnd object function D is relative to secondary graphics coefficient matrixGradient matrixAnd by main graph coefficient matrixOptimization direction matrixIt is initialized as：By auxiliary view Shape coefficient matrixOptimization direction matrixIt is initialized as

Step 103, when light source be parametrization light source when, permanent mask figure, based on current Ω_σAnd P_s ⁰, using conjugate gradient Method, to Ω_σCarry out 1 renewal；

When light source of the light source for pixelation, permanent mask figure, based on current Ω_sWithUsing conjugate gradient method, to Ω_sEnter 1 renewal of row, and in the updated by the point intensity level zero setting of pupil outer light source；

Step 104, calculating current light source figure, and calculate current light source figure and binary mask pattern M_bCorresponding imaging is protected True degree function F, when F is less than predetermined threshold ε_F, into step 111, as renewal light source parameters Ω_σOr Ω_sNumber of times reach it is predetermined on During limit value, into step 105, otherwise return to step 103；

Step 105, the main graph coefficient matrix based on initializationWith optimization direction matrixUsing conjugate gradient method pair Main graph coefficient matrix Θ_MPixel value carry out 1 renewal, and in the updated by Θ_MAll pixels value be limited to [0,1] In the range of, wherein the pixel value more than 1 is set as 1, the pixel value less than 0 is set as 0, the pixel value in the range of [0,1] Keep constant；

Step 106, calculating main graph binary coefficient matrix Θ_Mb=Γ { Θ_M-0.5}；By the main body graphical configuration of N × N ForWherein W_MIt is main body figure basic module, its pixel value is 0 or 1；Calculate mask Main graph M_b,mainIn polygon number, if the current polygon number for calculating is compared with last time circulation be not changed in, Then enter step 108, otherwise into step 107；

Step 107, by main graph coefficient matrix Θ_MValue revert to value before this is recycled into step 105, based on first The main graph coefficient matrix of beginningizationWith optimization direction matrixAnd use improved conjugate gradient method and endless form pair Corresponding to the coefficient matrix Θ of main body pattern edge_MPixel value be iterated renewal, until the side of current topic figure Untill edge no longer changes；And every time in iteration by matrix Θ_MAll pixels value be limited in the range of [0,1], wherein more than 1 Pixel value is set as 1, and the pixel value less than 0 is set as 0, and the pixel value in the range of [0,1] keeps constant；And calculate main body Figure binary coefficient matrix Θ_Mb=Γ { Θ_M-0.5}；

Step 108, the secondary graphics coefficient matrix based on initializationOptimization direction matrixUsing conjugate gradient method to auxiliary Geometry factor matrix Θ_SPixel value carry out 1 renewal, and all pixels value is limited in the range of [0,1] in the updated, its In be set as 1 more than 1 pixel value, the pixel value less than 0 is set as 0, and the pixel value in the range of [0,1] keeps constant； Afterwards, in order to ensure the minimum range between main graph and secondary graphics is more than or equal to threshold epsilon_D, by Θ_SIt is modified to：

Calculate secondary graphics binary coefficient matrix Θ_Sb=Γ { Θ_S-0.5}；Wherein pixel_MIt is the unilateral chi of pixel in mask plane It is very little, N_WSIt is the single side size of mask secondary graphics basic module；

Step 109, when light source be parametrization light source when, based on current Ω_σAnd P_s ⁰, using conjugate gradient method, to Ω_σCarry out 1 Secondary renewal；

When light source of the light source for pixelation, based on current Ω_sWithUsing conjugate gradient method, to Ω_s1 renewal is carried out, And will in the updated by the point intensity level zero setting of pupil outer light source；

Step 110, calculating current light source figure and binary mask pattern M_b, and calculate current light source figure and binary mask figure Shape M_bCorresponding imaging fidelity function F；When F is less than predetermined threshold ε_FOr circulation step 105 to step 109 is joined to light source When the number of times that number and mask parameters are iterated renewal reaches predetermined upper limit value, into step 111, otherwise return to step 105；

Step 111, terminate optimization, and by current light source figure and binary mask pattern M_bIt is defined as by the light source figure after optimization Shape and mask graph, and correct the edge protuberance that cannot be manufactured in the mask graph；

Step 112, the mask graph obtained by step 111 is masked shadow effect compensation, obtain final photomask optimization As a result.

2. EUV lithography light source-mask combined optimization method according to claim 1, it is characterised in that

The imaging fidelity function F is defined as：The difference of each pixel is imaged in targeted graphical and the corresponding photoresist of current mask Square weighted sum between Euler's distance quadratic sum.

3. EUV lithography light source-mask combined optimization method according to claim 2, it is characterised in that

The calculation procedure being imaged in the corresponding photoresist of the current mask figure is：

Step 201, mask graph M grids are turned into N × N number of subregion；

Step 202, surface of light source is tiled into by multiple spot lights according to the shape of partially coherent light source, with each grid region Heart point coordinates (x_s,y_s) represent spot light coordinate corresponding to the grid region；

Step 203, for single spot light, using its coordinate (x_s,y_s) when obtaining the spot light on correspondence wafer position Aerial imageWhereinIt is corresponding to spot light (x_s,y_s) etching system Point spread function,It is corresponding to spot light (x_s,y_s) mask diffraction matrices, symbol ⊙ representing matrixs or vector Corresponding element multiplication operation,Represent the complex number space of N × N；

Step 204, judge whether to have calculated aerial image on all spot lights correspondence wafer positions, if so, then entering step Rapid 205, otherwise return to step 203；

Step 205, according to Abbe method, aerial image I (x corresponding to each spot light_s,y_s) be overlapped, fetching portion coherent light During source lighting, the aerial image on wafer position：

WhereinIt is normalization factor；

Step 206, in view of the veiling glare having in EUV lithography system to the influence caused by aerial image, by step 205 The aerial image I for being obtained₀It is modified toWherein TIS is overall dispersion factor, PSF_fIt is one The matrix of N × N, represents veiling glare point spread function, PSF_fIt is represented by：

$\begin{array}{ccc}{\mathrm{PSF}}_f\left(\stackrel{\→}{r}\right)=\frac{K}{|\stackrel{\→}{r}{|}^{n_f+1}},& for& \left|\stackrel{\→}{r}\right|>r_{\min },\end{array}$

Wherein It is the position coordinates on chip, n_fIt is spectral index, r_minRepresent low Compass between frequency phase error and high-frequency phase error；

Step 207, based on EUV lithography glue approximate model, be calculated as being imaged in the corresponding photoresist of mask graph：Wherein It is PSF_rVariance, t_rFor Photoresist threshold value.

4. EUV lithography light source-mask combined optimization method according to claim 1, it is characterised in that

Using conjugate gradient method to Ω in the step 103,105,108 and 109_σAnd matrix Ω_s、Θ_MΘ_SPixel value carry out The detailed process of 1 renewal is that wherein symbolization X represents Ω_σ、Ω_s、Θ_MOr Θ_S, symbolization Θ represents Θ_MOr Θ_S, adopt P is represented with symbol P_S、P_SOr P_M：

Step 401, renewal coefficient matrix X are：X^k+1=X^k+s×P^k, wherein, s is optimization step-length set in advance, It is optimization direction matrix；

If step 402, now renewal light source parameters Ω_σOr Ω_s, then this step to 403 is skipped；If now updating light source parameters Θ_M Or Θ_S, then following steps are performed：

The pixel value of Θ is limited in [0,1] interval, i.e.,：

Step 403, calculating parameter β areWhereinRepresent to matrix modulus and squared；

Step 404, renewal optimization direction matrix P are：

5. EUV lithography light source-mask combined optimization method according to claim 1, it is characterised in that

Using improved conjugate gradient method and endless form to the coefficient corresponding to main body pattern edge in the step 107 Matrix Θ_MPixel value be iterated the detailed process of renewal and be：

Step 501, renewal binary coefficient matrix are Θ_Mb=Γ { Θ_M- 0.5 }, updating main body figure isCalculate M_b,mainProfileFor：

Meanwhile, current coefficient matrix is designated as Θ '_M；

Step 502, renewal coefficient matrix Θ_MFor：Wherein s is optimization step-length set in advance, Updating optimization direction matrix is：

Step 503, by Θ_MPixel value be limited in [0,1] it is interval in, i.e.,：

Step 504, according to current Θ_MCalculate Θ_Mb=Γ { Θ_M- 0.5 }, updateAnd more New M_b,mainProfileFor：

If nowBefore being updated with step 504Compared to then return to step 502 are varied from, otherwise into step 505；

Step 505, calculating parameter β_MFor

Step 506, will optimization direction matrix P be updated to：

6. EUV lithography light source-mask combined optimization method according to claim 1, it is characterised in that

In the step 111, binary mask pattern M is corrected_bIn the edge protuberance that cannot manufacture concretely comprise the following steps：

Step 601, the position for calculating all concave crown points in current binary mask pattern, wherein concave crown point are defined as in mask graph Portion forms 270 ° of summits at angle；

All concave crown points in step 602, traversal binary mask pattern, and correct run into first of traversal and cannot manufacture Edge protuberance；Specially：If the corresponding edge protuberance of concave crown point is the edge protuberance that cannot be manufactured, this edge protuberance is entered Two kinds of amendments of row, that is, fill and scabble, and respectively obtains two revised binary mask patterns：M′_bWith M "_b；It is imaged using scalar Model calculates correspondence M ' respectively_bWith M "_bImaging fidelity function F ' and F "；If F ' ＜ F " if by current binary mask pattern more It is newly M '_b, current binary mask pattern is otherwise updated to M "_b；The wherein described edge protuberance that cannot manufacture is：If edge is convex The height for rising is w_H, the both sides brachium of edge protuberance is respectively w_L1And w_L1, ε_HAnd ε_LIt is threshold value；When certain edge protuberance meets w_H≤ ε_HAnd w_L1Or w_L2≤ε_L, then this projection is called the edge protuberance that cannot be manufactured；

Step 603, judge whether the edge protuberance that cannot manufacture is corrected in step 602, if then entering step 601, otherwise, show do not existed the edge protuberance that cannot be manufactured in current binary mask image, now into step 112.

7. EUV lithography light source-mask combined optimization method according to claim 1, it is characterised in that

Concretely comprising the following steps for shadow effect compensation is masked in the step 112 to the mask graph obtained by step 111：

Step 701, coordinate system is set in the exposure field of EUV lithography machine annular sector, wherein origin is in exposure field center, Y-axis positive direction points to the center of circle of annular sector exposure field, and x-axis is vertical with y-axis, and is rotated by 90 ° from x-axis positive direction square to y-axis To for counterclockwise；

Step 702, for certain pattern edge on mask, calculate the corresponding parameter alpha in the edge_s, i.e.,：Wherein α_s' it is the azimuth at the mask graph edge, W is The width of annular sector exposure field, F is the angular aperture of annular sector exposure field；X is the exposure field position residing for mask graph edge The x-axis coordinate put；

Step 703, calculate the corresponding mask shade width B in the mask graph edge_s, work as α_sAt >=90 °,Work as α_sDuring 90 ° of ＜,Wherein B_{max_near}It is the figure nearer apart from light source The maximum shade width at shape edge, B_{max_far}It is the maximum shade width of the pattern edge apart from light source farther out, n_sIt is modifying factor Son, parameter B_{max_near}、B_{max_far}And n_sCan be drawn by data fitting；

Step 704, by the outside extension width B in the mask graph edge_s；

Step 705, judge whether to have have modified all mask graph edges, if so, then using current mask figure as compensation Mask graph after mask shadow effect, otherwise return to step 702.