Considering the efficiency and veracity of rules based optical proximity correction (OPC),the importance of rules in rules based OPC is pointed out.And how to select,to construct and to apply more concise and practi...Considering the efficiency and veracity of rules based optical proximity correction (OPC),the importance of rules in rules based OPC is pointed out.And how to select,to construct and to apply more concise and practical rules base is disscussed.Based on those ideas,four primary rules are suggested.Some data resulted in rules base are shown in table.The patterns on wafer are clearly improved by applying these rules to correct mask.OPCL,the automatic construction of the rules base is an important part of the whole rules based OPC system.展开更多
The shrinking of the size of the advanced technological nodes brings up new challenges to the semiconductor manufacturing community.The optical proximity correction(OPC)is invented to reduce the errors of the lithogra...The shrinking of the size of the advanced technological nodes brings up new challenges to the semiconductor manufacturing community.The optical proximity correction(OPC)is invented to reduce the errors of the lithographic process.The conventional OPC techniques rely on the empirical models and optimization methods of iterative type.Both the accuracy and computing speed of the existing OPC techniques need to be improved to fulfill the stringent requirement of the research and design for latest technological nodes.The emergence of machine learning technologies inspires novel OPC algorithms.More accurate forward simulation of the lithographic process and single turn optimization methods are enabled by the machine learning based OPC techniques.We discuss the latest progress made by the OPC community in the process simulation and optimization based on machine learning techniques.展开更多
A wavefront sensing and correction correction is proposed that would allow the field of view (FOV) of an adaptive optics spstem to be increased in size by a factor of several tens. This concept is based on the idea of...A wavefront sensing and correction correction is proposed that would allow the field of view (FOV) of an adaptive optics spstem to be increased in size by a factor of several tens. This concept is based on the idea of placing multiple deformable mirrors (DMs) at locations that are conjugate to corresponding. layers of atmospheric turbulence. In order to control properly each DM, a tomographic method for determining the phase distortion contributed by each atmospheric layer has been developed and used in dealing with the circumstance of two layers.展开更多
To acquire high-quality operational data products for Chinese in-orbit and scheduled ocean color sensors, the performances of two operational atmospheric correction(AC) algorithms(ESA MEGS 7.4.1 and NASA Sea DAS 6.1) ...To acquire high-quality operational data products for Chinese in-orbit and scheduled ocean color sensors, the performances of two operational atmospheric correction(AC) algorithms(ESA MEGS 7.4.1 and NASA Sea DAS 6.1) were evaluated over the East China Seas(ECS) using MERIS data. The spectral remote sensing reflectance R_(rs)(λ), aerosol optical thickness(AOT), and ?ngstr?m exponent(α) retrieved using the two algorithms were validated using in situ measurements obtained between May 2002 and October 2009. Match-ups of R_(rs), AOT, and α between the in situ and MERIS data were obtained through strict exclusion criteria. Statistical analysis of R_(rs)(λ) showed a mean percentage difference(MPD) of 9%–13% in the 490–560 nm spectral range, and significant overestimation was observed at 413 nm(MPD>72%). The AOTs were overestimated(MPD>32%), and although the ESA algorithm outperformed the NASA algorithm in the blue-green bands, the situation was reversed in the red-near-infrared bands. The value of α was obviously underestimated by the ESA algorithm(MPD=41%) but not by the NASA algorithm(MPD=35%). To clarify why the NASA algorithm performed better in the retrieval of α, scatter plots of the α single scattering albedo(SSA) density were prepared. These α-SSA density scatter plots showed that the applicability of the aerosol models used by the NASA algorithm over the ECS is better than that used by the ESA algorithm, although neither aerosol model is suitable for the ECS region. The results of this study provide a reference to both data users and data agencies regarding the use of operational data products and the investigation into the improvement of current AC schemes over the ECS.展开更多
A magnetic fluid based deformable mirror(MFDM) that could produce a large stroke more than 100 μm is designed and demonstrated experimentally with respect to the characteristics of the aberration of the liquid telesc...A magnetic fluid based deformable mirror(MFDM) that could produce a large stroke more than 100 μm is designed and demonstrated experimentally with respect to the characteristics of the aberration of the liquid telescope. Its aberration correction performance is verified by the co-simulation using COMSOL and MATLAB. Furthermore, the stroke performance of the MFDM and the decentralized linear quadratic Gaussian(LQG) mirror surface control approach are experimentally evaluated with a prototype of MFDM in an adaptive optics system to show its potential application for the large aberration correction of liquid telescopes.展开更多
This paper proposed a method to retrieve the land surface reflectance from the HJ-1A/B CCD data. The aerosol optical depth（AOD）, the most important factor affecting the atmospheric correction of CCD images at all ba...This paper proposed a method to retrieve the land surface reflectance from the HJ-1A/B CCD data. The aerosol optical depth（AOD）, the most important factor affecting the atmospheric correction of CCD images at all bands, is proposed to retrieve from the CCD imagery by the approach of dense dark vegetation（DDV） method. A look-up table in terms of the transmittances, the path radiances and the atmospheric spherical albedo as functions of the AOD was established for a variety of sun-sensor geometry and aerosol loadings. The atmospheric correction is then achieved with the look-up table and the MODIS surface reflectance output（MOD09） as the priori datasets. Based on the retrieved AOD and the look-up table of atmospheric correction coefficients, the land surface reflectance was retrieved for the HJ-1A/B data according to the atmospheric radiative transfer equation. Some in-situ measurement Data for Yanzhou of Shandong province in East China and MODIS land surface reflectance products MOD09 are used to preliminarily validate the proposed method. The results show that the proposed method can remove effectively the atmospheric contributions, and the overall accuracy of the retrieval land surface reflectance can be improved substantially.展开更多
With the continued shrinking of the critical dimensions(CDs)of wafer patterning,the requirements for modeling precision in optical proximity correction(OPC)increase accordingly.This requirement extends beyond CD contr...With the continued shrinking of the critical dimensions(CDs)of wafer patterning,the requirements for modeling precision in optical proximity correction(OPC)increase accordingly.This requirement extends beyond CD controlling accuracy to include pattern alignment accuracy because misalignment can lead to considerable overlay and metal-via coverage issues at advanced nodes,affecting process window and yield.This paper proposes an efficient OPC modeling approach that prioritizes pattern-shift-related elements to tackle the issue accurately.Our method integrates careful measurement selection,the implementation of pattern-shift-aware structures in design,and the manipulation of the cost function during model tuning to establish a robust model.Confirmatory experiments are performed on a via layer fabricated using a negative tone development.Results demonstrate that pattern shifts can be constrained within a range of+1 nm,remarkably better than the original range of±3 nm.Furthermore,simulations reveal notable differences between post OPC and original masks when considering pattern shifts at locations sensitive to this phenomenon.Experimental validation confirms the accuracy of the proposed modeling approach,and a firm consistency is observed between the simulation results and experimental data obtained from actual design structures.展开更多
Optical proximity correction (OPC) systems require an accurate and fast way to predict how patterns will be transferred to the wafer.Based on Gabor's 'reduction to principal waves',a partially coherent ima...Optical proximity correction (OPC) systems require an accurate and fast way to predict how patterns will be transferred to the wafer.Based on Gabor's 'reduction to principal waves',a partially coherent imaging system can be represented as a superposition of coherent imaging systems,so an accurate and fast sparse aerial image intensity calculation algorithm for lithography simulation is presented based on convolution kernels,which also include simulating the lateral diffusion and some mask processing effects via Gaussian filter.The simplicity of this model leads to substantial computational and analytical benefits.Efficiency of this method is also shown through simulation results.展开更多
We describe a post resolution-enhancement-technique verification method for use in manufacturing data flow. The goal of the method is to verify whether designs function as intended,or more precisely, whether the print...We describe a post resolution-enhancement-technique verification method for use in manufacturing data flow. The goal of the method is to verify whether designs function as intended,or more precisely, whether the printed images are consistent with the design intent. The process modeling is described for the model-based verifi cation method. The performance of the method is demonstrated by experiment.展开更多
AIMTo evaluate the intra-operator repeatability in healthy subjects using the WAM-5500 auto-kerato/refractometer and the iTrace aberrometer, to compare the refractive values and the subjective refraction obtained with...AIMTo evaluate the intra-operator repeatability in healthy subjects using the WAM-5500 auto-kerato/refractometer and the iTrace aberrometer, to compare the refractive values and the subjective refraction obtained with both devices and to determine which of these three spherocylindrical corrections allows the subject to achieve the best visual comfort.METHODSForty-two non-presbyopic healthy eyes of 42 subjects were enrolled in this prospective study. Refractive values were compared, evaluating the repeatability, the relationship between the methods and the best visual comfort obtained.RESULTSSphere, cylinder and axis results showed good intraclass correlation coefficients (ICC); the highest ICC was obtained using the spherical refraction with the autorefractometer and the aberrometer, achieving levels of 0.999 and 0.998, respectively. The power vector (PV) was calculated for each refraction method, and the results indicated that there were no statistically significant differences between them (P>0.05). Direct comparison of PV measurements using the three methods showed that aberrometer refraction gave the highest values, followed by the subjective values; the autorefractometer gave the lowest values. The subjective method correction was most frequently chosen as the first selection. Equal values were found for the autorefractometer and the aberrometer as the second selection.CONCLUSIONThe iTrace aberrometer and the WAM-5500 auto-kerato/refractometer showed high levels of repeatability in healthy eyes. Refractive corrections with the aberrometer, the autorefractometer and subjective methods presented similar results, but spherocylindrical subjective correction was the most frequently selected option. These technologies can be used as complements in refractive evaluation, but they should not replace subjective refraction.展开更多
The empirical models of sulfide capacity calculated by traditional optical basicity do not consider the charge compensation of alkaline metal ions to AP＋ in the molten slags, so that the deviations between the calcul...The empirical models of sulfide capacity calculated by traditional optical basicity do not consider the charge compensation of alkaline metal ions to AP＋ in the molten slags, so that the deviations between the calculated values and measured ones of sulfide capacity are inevitable. The relation between sulfide capacity and the corrected optical basicity put forward by Mills considering the charge compensation was investigated. Combined with the relation be- tween sulfide capacity and temperatures, a novel and accurate calculation model of sulfide capacity was proposed, which was applied to calculate the sulfide capacities of CaO-Al2 O3-SiO2-MgO and CaO-Al2 03-SiO2-MgO-TiO2 sys-tems, where the sum of the CaO and MgO concentrations in the slags must be not lower than the Al2O3 concentra tion. It was also found that the calculated values were in a good agreement with the measured values, and the mean deviations were 2.57% and 2.65%, respectively.展开更多
Optical proximity correction (OPC) is a key step in modern integrated circuit (IC) manufacturing.The quality of model-based OPC (MB-OPC) is directly determined by segment offsets after OPC processing.However,in conven...Optical proximity correction (OPC) is a key step in modern integrated circuit (IC) manufacturing.The quality of model-based OPC (MB-OPC) is directly determined by segment offsets after OPC processing.However,in conventional MB-OPC,the intensity of a control site is adjusted only by the movement of its corresponding segment;this scheme is no longer accurate enough as the lithography process advances.On the other hand,matrix MB-OPC is too time-consuming to become practical.In this paper,we propose a new sparse matrix MB-OPC algorithm with model-based mapping between segments and control sites.We put forward the concept of 'sensitive area'.When the Jacobian matrix used in the matrix MB-OPC is evaluated,only the elements that correspond to the segments in the sensitive area of every control site need to be calculated,while the others can be set to 0.The new algorithm can effectively improve the sparsity of the Jacobian matrix,and hence reduce the computations.Both theoretical analysis and experiments show that the sparse matrix MB-OPC with model-based mapping is more accurate than conventional MB-OPC,and much faster than matrix MB-OPC while maintaining high accuracy.展开更多
Computational lithography(CL)has become an indispensable technology to improve imaging resolution and fidelity of deep sub-wavelength lithography.The state-of-the-art CL approaches are capable of optimizing pixel-base...Computational lithography(CL)has become an indispensable technology to improve imaging resolution and fidelity of deep sub-wavelength lithography.The state-of-the-art CL approaches are capable of optimizing pixel-based mask patterns to effectively improve the degrees of optimization freedom.However,as the growth of data volume of photomask layouts,computational complexity has become a challenging problem that prohibits the applications of advanced CL algorithms.In the past,a number of innovative methods have been developed to improve the computational efficiency of CL algorithms,such as machine learning and deep learning methods.Based on the brief introduction of optical lithography,this paper reviews some recent advances of fast CL approaches based on deep learning.At the end,this paper briefly discusses some potential developments in future work.展开更多
AIM： To analyze the clinical factors influencing the human vision corrections via the changing of ocular components of human eye in various applications; and to analyze refractive state via a new effective axial leng...AIM： To analyze the clinical factors influencing the human vision corrections via the changing of ocular components of human eye in various applications; and to analyze refractive state via a new effective axial length.METHODS： An effective eye model was introduced by the ocular components of human eye including refractive indexes, surface radius（r1, r2, R1, R2） and thickness（t, T） of the cornea and lens, the anterior chamber depth（S1） and the vitreous length（S2）. Gaussian optics was used to calculate the change rate of refractive error per unit amount of ocular components of a human eye（the rate function M）. A new criterion of myopia was presented via an effective axial length.RESULTS： For typical corneal and lens power of 42 and 21.9 diopters, the rate function Mj（j=1 to 6） were calculated for a 1% change of r1, r2, R1, R2, t, T（in diopters） M1=＋0.485, M2=-0.063, M3=＋0.053, M4=＋0.091, M5=＋0.012, and M6=-0.021 diopters. For 1.0 mm increase of S1 and S2, the rate functions were M7=＋1.35, and M8=-2.67 diopter/mm, respectively. These rate functions were used to analyze the clinical outcomes in various applications including laser in situ keratomileusis surgery, corneal cross linking procedure, femtosecond laser surgery and scleral ablation for accommodation.CONCLUSION： Using Gaussian optics, analytic formulas are presented for the change of refractive power due to various ocular parameter changes. These formulas provide useful clinical guidance in refractive surgery and other related procedures.展开更多
With the continuous decrease in the critical dimensions of integrated circuits, mask optimization has becomethe main challenge in VLSI design. In recent years, thriving machine learning has been gradually introduced i...With the continuous decrease in the critical dimensions of integrated circuits, mask optimization has becomethe main challenge in VLSI design. In recent years, thriving machine learning has been gradually introduced in the field ofoptical proximity correction (OPC). Currently, advanced learning-based frameworks have been limited by low mask printability or large computational overhead. To address these limitations, this paper proposes a learning-based frameworknamed SegNet-OPC, which can generate optimized masks from the target layout at shorter training and turnaround timewith higher mask printability. The proposed framework consists of a backbone network and loss terms suitable for maskoptimization tasks, followed by a fine-tuning network. The framework yields remarkable improvements over conventionalmethods, delivering significantly faster turnaround time and superior mask printability and manufacturability. With just1.25 hours of training, the framework achieves comparable mask complexity while surpassing the state-of-the-art methods,achieving a minimum 3% enhancement in mask printability and an impressive 16.7% improvement in mask manufacturability.展开更多
Inverse lithography technology(ILT)is a promising approach in computational lithography to address the challenges posed by shrinking semiconductor device dimensions.The ILT leverages optimization algorithms to generat...Inverse lithography technology(ILT)is a promising approach in computational lithography to address the challenges posed by shrinking semiconductor device dimensions.The ILT leverages optimization algorithms to generate mask patterns,outperforming traditional optical proximity correction methods.This review provides an overview of ILT's principles,evolution,and applications,with an emphasis on integration with artificial intelligence(AI)techniques.The review tracks recent advancements of ILT in model improvement and algorithmic efficiency.Challenges such as extended computational runtimes and mask-writing complexities are summarized,with potential solutions discussed.Despite these challenges,AI-driven methods,such as convolutional neural networks,deep neural networks,generative adversarial networks,and model-driven deep learning methods,are transforming ILT.AI-based approaches offer promising pathways to overcome existing limitations and support the adoption in high-volume manufacturing.Future research directions are explored to exploit ILT's potential and drive progress in the semiconductor industry.展开更多
As semiconductor manufacturing moves toward fine feature sizes,precise and efficient resist model calibration has become crucial for optical proximity correction to ensure pattern fidelity.However,traditional calibrat...As semiconductor manufacturing moves toward fine feature sizes,precise and efficient resist model calibration has become crucial for optical proximity correction to ensure pattern fidelity.However,traditional calibration methods struggle with efficiency and scalability and are prone to becoming trapped in local optima.Herein,we propose a surrogate-assisted genetic algorithm(SAGA)that integrates Kriging interpolation-based surrogate models and dynamic adaptive mechanisms to optimize resist model coefficients,convolution kernel parameters,and aerial image settings jointly.By leveraging surrogate models to predict high-performance solutions and adaptively adjusting crossover/mutation rates,SAGA balances global exploration and local exploitation,achieving rapid convergence and superior model accuracy compared with other algorithms.Experimental validation across three resist cases demonstrates that SAGA outperforms conventional genetic algorithms and grid search.Compared with other algorithms,SAGA not only achieves higher accuracy but also converges faster,with its optimization trajectories stabilizing earlier in the iterative process.These results highlight SAGA’s potential for efficient and high-precision resist calibration in computational lithography.展开更多
Adaptive optics(AO)is a powerful tool employed across various research fields,from aerospace to microscopy.Traditionally,AO has focused on correcting optical phase aberrations,with recent advances extending to polaris...Adaptive optics(AO)is a powerful tool employed across various research fields,from aerospace to microscopy.Traditionally,AO has focused on correcting optical phase aberrations,with recent advances extending to polarisation compensation.However,intensity errors are also prevalent in optical systems,yet effective correction methods are still in their infancy.Here,we introduce a novel AO approach,termed intensity adaptive optics(I-AO),which employs a dual-feedback loop mechanism to first address non-uniform intensity distribution and subsequently compensate for energy loss at the pupil plane.We demonstrate that I-AO can operate in both sensor-based and sensorless formats and validate its feasibility by quantitatively analysing the focus quality of an aberrated system.This technique expands the AO toolkit,paving the way for next-generation AO technology.展开更多
In this paper,a method of 3D reconstruction from two images acquired by two panoramic cameras is presented.Firstly,the features of the reconstruction object detected in each image are matched through the DP matching m...In this paper,a method of 3D reconstruction from two images acquired by two panoramic cameras is presented.Firstly,the features of the reconstruction object detected in each image are matched through the DP matching method.Secondly,optical correction is carried out on two cameras,and the internal parameters of panoramic cameras can be calculated.Finally,according to the calibration method,the geometric relationship between corresponding points in space and in two panoramic images is deduced.The results indicate that the method of 3D reconstruction based on two panoramic cameras is simple,and the accuracy can reach 98.82%.展开更多
Inverse lithography technology(ILT),also known as pixel-based optical proximity correction(PB-OPC),has shown promising capability in pushing the current 193 nm lithography to its limit.By treating the mask optimizatio...Inverse lithography technology(ILT),also known as pixel-based optical proximity correction(PB-OPC),has shown promising capability in pushing the current 193 nm lithography to its limit.By treating the mask optimization process as an inverse problem in lithography,ILT provides a more complete exploration of the solution space and better pattern fidelity than the traditional edge-based OPC.However,the existing methods of ILT are extremely time-consuming due to the slow convergence of the optimization process.To address this issue,in this paper we propose a support vector machine(SVM)based layout retargeting method for ILT,which is designed to generate a good initial input mask for the optimization process and promote the convergence speed.Supervised by optimized masks of training layouts generated by conventional ILT,SVM models are learned and used to predict the initial pixel values in the‘undefined areas’of the new layout.By this process,an initial input mask close to the final optimized mask of the new layout is generated,which reduces iterations needed in the following optimization process.Manufacturability is another critical issue in ILT;however,the mask generated by our layout retargeting method is quite irregular due to the prediction inaccuracy of the SVM models.To compensate for this drawback,a spatial filter is employed to regularize the retargeted mask for complexity reduction.We implemented our layout retargeting method with a regularized level-set based ILT(LSB-ILT)algorithm under partially coherent illumination conditions.Experimental results show that with an initial input mask generated by our layout retargeting method,the number of iterations needed in the optimization process and runtime of the whole process in ILT are reduced by 70.8%and 69.0%,respectively.展开更多
文摘Considering the efficiency and veracity of rules based optical proximity correction (OPC),the importance of rules in rules based OPC is pointed out.And how to select,to construct and to apply more concise and practical rules base is disscussed.Based on those ideas,four primary rules are suggested.Some data resulted in rules base are shown in table.The patterns on wafer are clearly improved by applying these rules to correct mask.OPCL,the automatic construction of the rules base is an important part of the whole rules based OPC system.
基金by National Science and Technology Major Project of China(2017ZX02315001-003,2017ZX02101004-003)National Natural Science Foundation of China(61874002,61804174),Beijing Natural Fund(4182021).
文摘The shrinking of the size of the advanced technological nodes brings up new challenges to the semiconductor manufacturing community.The optical proximity correction(OPC)is invented to reduce the errors of the lithographic process.The conventional OPC techniques rely on the empirical models and optimization methods of iterative type.Both the accuracy and computing speed of the existing OPC techniques need to be improved to fulfill the stringent requirement of the research and design for latest technological nodes.The emergence of machine learning technologies inspires novel OPC algorithms.More accurate forward simulation of the lithographic process and single turn optimization methods are enabled by the machine learning based OPC techniques.We discuss the latest progress made by the OPC community in the process simulation and optimization based on machine learning techniques.
文摘A wavefront sensing and correction correction is proposed that would allow the field of view (FOV) of an adaptive optics spstem to be increased in size by a factor of several tens. This concept is based on the idea of placing multiple deformable mirrors (DMs) at locations that are conjugate to corresponding. layers of atmospheric turbulence. In order to control properly each DM, a tomographic method for determining the phase distortion contributed by each atmospheric layer has been developed and used in dealing with the circumstance of two layers.
基金Supported by the State Key Program of National Natural Science Foundation of China(No.60638020)the State Scholarship Fund of the China Scholarship Council(CSC)+1 种基金the National Natural Science Foundation of China(Nos.41321004,41276028,41206006,41306192,41306035)the Natural Science Foundation of Zhejiang Province(No.LY15D060001)
文摘To acquire high-quality operational data products for Chinese in-orbit and scheduled ocean color sensors, the performances of two operational atmospheric correction(AC) algorithms(ESA MEGS 7.4.1 and NASA Sea DAS 6.1) were evaluated over the East China Seas(ECS) using MERIS data. The spectral remote sensing reflectance R_(rs)(λ), aerosol optical thickness(AOT), and ?ngstr?m exponent(α) retrieved using the two algorithms were validated using in situ measurements obtained between May 2002 and October 2009. Match-ups of R_(rs), AOT, and α between the in situ and MERIS data were obtained through strict exclusion criteria. Statistical analysis of R_(rs)(λ) showed a mean percentage difference(MPD) of 9%–13% in the 490–560 nm spectral range, and significant overestimation was observed at 413 nm(MPD>72%). The AOTs were overestimated(MPD>32%), and although the ESA algorithm outperformed the NASA algorithm in the blue-green bands, the situation was reversed in the red-near-infrared bands. The value of α was obviously underestimated by the ESA algorithm(MPD=41%) but not by the NASA algorithm(MPD=35%). To clarify why the NASA algorithm performed better in the retrieval of α, scatter plots of the α single scattering albedo(SSA) density were prepared. These α-SSA density scatter plots showed that the applicability of the aerosol models used by the NASA algorithm over the ECS is better than that used by the ESA algorithm, although neither aerosol model is suitable for the ECS region. The results of this study provide a reference to both data users and data agencies regarding the use of operational data products and the investigation into the improvement of current AC schemes over the ECS.
基金supported by the National Natural Science Foundation of China(No.51675321)the Shanghai Municipal Natural Science Foundation(No.15ZR1415800)the Innovation Program of Shanghai Municipal Education Commission(No.14ZZ092)
文摘A magnetic fluid based deformable mirror(MFDM) that could produce a large stroke more than 100 μm is designed and demonstrated experimentally with respect to the characteristics of the aberration of the liquid telescope. Its aberration correction performance is verified by the co-simulation using COMSOL and MATLAB. Furthermore, the stroke performance of the MFDM and the decentralized linear quadratic Gaussian(LQG) mirror surface control approach are experimentally evaluated with a prototype of MFDM in an adaptive optics system to show its potential application for the large aberration correction of liquid telescopes.
基金National High Technology Research and Development Program of China,No.2012AA12A302
文摘This paper proposed a method to retrieve the land surface reflectance from the HJ-1A/B CCD data. The aerosol optical depth（AOD）, the most important factor affecting the atmospheric correction of CCD images at all bands, is proposed to retrieve from the CCD imagery by the approach of dense dark vegetation（DDV） method. A look-up table in terms of the transmittances, the path radiances and the atmospheric spherical albedo as functions of the AOD was established for a variety of sun-sensor geometry and aerosol loadings. The atmospheric correction is then achieved with the look-up table and the MODIS surface reflectance output（MOD09） as the priori datasets. Based on the retrieved AOD and the look-up table of atmospheric correction coefficients, the land surface reflectance was retrieved for the HJ-1A/B data according to the atmospheric radiative transfer equation. Some in-situ measurement Data for Yanzhou of Shandong province in East China and MODIS land surface reflectance products MOD09 are used to preliminarily validate the proposed method. The results show that the proposed method can remove effectively the atmospheric contributions, and the overall accuracy of the retrieval land surface reflectance can be improved substantially.
基金funded by the National Natural Science Foundation of China(Grant Nos.52130504,52305577,and 52205592)the Key Research and Development Plan of Hubei Province,China(Grant No.2022BAA013)+2 种基金the Major Program(JD)of Hubei Province,China(Grant No.2023BAA008-2)the Innovation Projection of Optics Valley Laboratory,China(Grant No.OVL2023PY003)the Postdoctoral Fellowship Program(Grade B)of the China Postdoctoral Science Foundation(Grant No.GZB20230244).
文摘With the continued shrinking of the critical dimensions(CDs)of wafer patterning,the requirements for modeling precision in optical proximity correction(OPC)increase accordingly.This requirement extends beyond CD controlling accuracy to include pattern alignment accuracy because misalignment can lead to considerable overlay and metal-via coverage issues at advanced nodes,affecting process window and yield.This paper proposes an efficient OPC modeling approach that prioritizes pattern-shift-related elements to tackle the issue accurately.Our method integrates careful measurement selection,the implementation of pattern-shift-aware structures in design,and the manipulation of the cost function during model tuning to establish a robust model.Confirmatory experiments are performed on a via layer fabricated using a negative tone development.Results demonstrate that pattern shifts can be constrained within a range of+1 nm,remarkably better than the original range of±3 nm.Furthermore,simulations reveal notable differences between post OPC and original masks when considering pattern shifts at locations sensitive to this phenomenon.Experimental validation confirms the accuracy of the proposed modeling approach,and a firm consistency is observed between the simulation results and experimental data obtained from actual design structures.
文摘Optical proximity correction (OPC) systems require an accurate and fast way to predict how patterns will be transferred to the wafer.Based on Gabor's 'reduction to principal waves',a partially coherent imaging system can be represented as a superposition of coherent imaging systems,so an accurate and fast sparse aerial image intensity calculation algorithm for lithography simulation is presented based on convolution kernels,which also include simulating the lateral diffusion and some mask processing effects via Gaussian filter.The simplicity of this model leads to substantial computational and analytical benefits.Efficiency of this method is also shown through simulation results.
文摘We describe a post resolution-enhancement-technique verification method for use in manufacturing data flow. The goal of the method is to verify whether designs function as intended,or more precisely, whether the printed images are consistent with the design intent. The process modeling is described for the model-based verifi cation method. The performance of the method is demonstrated by experiment.
基金Supported by the Government of Aragon,Group B99Fund of Health Research from Institute of Health Carlos Ⅲ(Spanish Ministry of Health)PS0901854 and PI13/01124University of Zaragoza grant FPUZ-2011-BIO-02
文摘AIMTo evaluate the intra-operator repeatability in healthy subjects using the WAM-5500 auto-kerato/refractometer and the iTrace aberrometer, to compare the refractive values and the subjective refraction obtained with both devices and to determine which of these three spherocylindrical corrections allows the subject to achieve the best visual comfort.METHODSForty-two non-presbyopic healthy eyes of 42 subjects were enrolled in this prospective study. Refractive values were compared, evaluating the repeatability, the relationship between the methods and the best visual comfort obtained.RESULTSSphere, cylinder and axis results showed good intraclass correlation coefficients (ICC); the highest ICC was obtained using the spherical refraction with the autorefractometer and the aberrometer, achieving levels of 0.999 and 0.998, respectively. The power vector (PV) was calculated for each refraction method, and the results indicated that there were no statistically significant differences between them (P>0.05). Direct comparison of PV measurements using the three methods showed that aberrometer refraction gave the highest values, followed by the subjective values; the autorefractometer gave the lowest values. The subjective method correction was most frequently chosen as the first selection. Equal values were found for the autorefractometer and the aberrometer as the second selection.CONCLUSIONThe iTrace aberrometer and the WAM-5500 auto-kerato/refractometer showed high levels of repeatability in healthy eyes. Refractive corrections with the aberrometer, the autorefractometer and subjective methods presented similar results, but spherocylindrical subjective correction was the most frequently selected option. These technologies can be used as complements in refractive evaluation, but they should not replace subjective refraction.
基金Sponsored by National Natural Science Foundation of China(51090384)
文摘The empirical models of sulfide capacity calculated by traditional optical basicity do not consider the charge compensation of alkaline metal ions to AP＋ in the molten slags, so that the deviations between the calculated values and measured ones of sulfide capacity are inevitable. The relation between sulfide capacity and the corrected optical basicity put forward by Mills considering the charge compensation was investigated. Combined with the relation be- tween sulfide capacity and temperatures, a novel and accurate calculation model of sulfide capacity was proposed, which was applied to calculate the sulfide capacities of CaO-Al2 O3-SiO2-MgO and CaO-Al2 03-SiO2-MgO-TiO2 sys-tems, where the sum of the CaO and MgO concentrations in the slags must be not lower than the Al2O3 concentra tion. It was also found that the calculated values were in a good agreement with the measured values, and the mean deviations were 2.57% and 2.65%, respectively.
文摘Optical proximity correction (OPC) is a key step in modern integrated circuit (IC) manufacturing.The quality of model-based OPC (MB-OPC) is directly determined by segment offsets after OPC processing.However,in conventional MB-OPC,the intensity of a control site is adjusted only by the movement of its corresponding segment;this scheme is no longer accurate enough as the lithography process advances.On the other hand,matrix MB-OPC is too time-consuming to become practical.In this paper,we propose a new sparse matrix MB-OPC algorithm with model-based mapping between segments and control sites.We put forward the concept of 'sensitive area'.When the Jacobian matrix used in the matrix MB-OPC is evaluated,only the elements that correspond to the segments in the sensitive area of every control site need to be calculated,while the others can be set to 0.The new algorithm can effectively improve the sparsity of the Jacobian matrix,and hence reduce the computations.Both theoretical analysis and experiments show that the sparse matrix MB-OPC with model-based mapping is more accurate than conventional MB-OPC,and much faster than matrix MB-OPC while maintaining high accuracy.
基金the financial support by the National Natural Science Foundation of China(NSFC)(61675021)the Fundamental Research Funds for the Central Universities(2020CX02002,2018CX01025)。
文摘Computational lithography(CL)has become an indispensable technology to improve imaging resolution and fidelity of deep sub-wavelength lithography.The state-of-the-art CL approaches are capable of optimizing pixel-based mask patterns to effectively improve the degrees of optimization freedom.However,as the growth of data volume of photomask layouts,computational complexity has become a challenging problem that prohibits the applications of advanced CL algorithms.In the past,a number of innovative methods have been developed to improve the computational efficiency of CL algorithms,such as machine learning and deep learning methods.Based on the brief introduction of optical lithography,this paper reviews some recent advances of fast CL approaches based on deep learning.At the end,this paper briefly discusses some potential developments in future work.
基金Supported by an Internal Research of New Vision Inc.,Taipei,Taiwan
文摘AIM： To analyze the clinical factors influencing the human vision corrections via the changing of ocular components of human eye in various applications; and to analyze refractive state via a new effective axial length.METHODS： An effective eye model was introduced by the ocular components of human eye including refractive indexes, surface radius（r1, r2, R1, R2） and thickness（t, T） of the cornea and lens, the anterior chamber depth（S1） and the vitreous length（S2）. Gaussian optics was used to calculate the change rate of refractive error per unit amount of ocular components of a human eye（the rate function M）. A new criterion of myopia was presented via an effective axial length.RESULTS： For typical corneal and lens power of 42 and 21.9 diopters, the rate function Mj（j=1 to 6） were calculated for a 1% change of r1, r2, R1, R2, t, T（in diopters） M1=＋0.485, M2=-0.063, M3=＋0.053, M4=＋0.091, M5=＋0.012, and M6=-0.021 diopters. For 1.0 mm increase of S1 and S2, the rate functions were M7=＋1.35, and M8=-2.67 diopter/mm, respectively. These rate functions were used to analyze the clinical outcomes in various applications including laser in situ keratomileusis surgery, corneal cross linking procedure, femtosecond laser surgery and scleral ablation for accommodation.CONCLUSION： Using Gaussian optics, analytic formulas are presented for the change of refractive power due to various ocular parameter changes. These formulas provide useful clinical guidance in refractive surgery and other related procedures.
基金supported by the Special Fund for Research on National Major Research Instruments of China under Grant No.62027815the National Natural Science Foundation of China under Grant Nos.61834006,62274052,and 61404001.
文摘With the continuous decrease in the critical dimensions of integrated circuits, mask optimization has becomethe main challenge in VLSI design. In recent years, thriving machine learning has been gradually introduced in the field ofoptical proximity correction (OPC). Currently, advanced learning-based frameworks have been limited by low mask printability or large computational overhead. To address these limitations, this paper proposes a learning-based frameworknamed SegNet-OPC, which can generate optimized masks from the target layout at shorter training and turnaround timewith higher mask printability. The proposed framework consists of a backbone network and loss terms suitable for maskoptimization tasks, followed by a fine-tuning network. The framework yields remarkable improvements over conventionalmethods, delivering significantly faster turnaround time and superior mask printability and manufacturability. With just1.25 hours of training, the framework achieves comparable mask complexity while surpassing the state-of-the-art methods,achieving a minimum 3% enhancement in mask printability and an impressive 16.7% improvement in mask manufacturability.
基金support by the National Natural Science Foundation of China(62235009).
文摘Inverse lithography technology(ILT)is a promising approach in computational lithography to address the challenges posed by shrinking semiconductor device dimensions.The ILT leverages optimization algorithms to generate mask patterns,outperforming traditional optical proximity correction methods.This review provides an overview of ILT's principles,evolution,and applications,with an emphasis on integration with artificial intelligence(AI)techniques.The review tracks recent advancements of ILT in model improvement and algorithmic efficiency.Challenges such as extended computational runtimes and mask-writing complexities are summarized,with potential solutions discussed.Despite these challenges,AI-driven methods,such as convolutional neural networks,deep neural networks,generative adversarial networks,and model-driven deep learning methods,are transforming ILT.AI-based approaches offer promising pathways to overcome existing limitations and support the adoption in high-volume manufacturing.Future research directions are explored to exploit ILT's potential and drive progress in the semiconductor industry.
基金funded by the National Natural Science Foundation of China(Grant Nos.52205592 and 52130504)Key Research and Development Plan of Hubei Province,China(Grant No.2022BAA013)+1 种基金Major Program(JD)of Hubei Province,China(Grant No.2023BAA008-2)Innovation Project of Optics Valley Laboratory,China(Grant No.OVL2023PY003)。
文摘As semiconductor manufacturing moves toward fine feature sizes,precise and efficient resist model calibration has become crucial for optical proximity correction to ensure pattern fidelity.However,traditional calibration methods struggle with efficiency and scalability and are prone to becoming trapped in local optima.Herein,we propose a surrogate-assisted genetic algorithm(SAGA)that integrates Kriging interpolation-based surrogate models and dynamic adaptive mechanisms to optimize resist model coefficients,convolution kernel parameters,and aerial image settings jointly.By leveraging surrogate models to predict high-performance solutions and adaptively adjusting crossover/mutation rates,SAGA balances global exploration and local exploitation,achieving rapid convergence and superior model accuracy compared with other algorithms.Experimental validation across three resist cases demonstrates that SAGA outperforms conventional genetic algorithms and grid search.Compared with other algorithms,SAGA not only achieves higher accuracy but also converges faster,with its optimization trajectories stabilizing earlier in the iterative process.These results highlight SAGA’s potential for efficient and high-precision resist calibration in computational lithography.
基金support of Dr.Yun Zhang and Prof.Daniel Royston at the University of Oxford,St John's College(C.H.),and the Royal Society(URF\R1/241734)(C.H.).
文摘Adaptive optics(AO)is a powerful tool employed across various research fields,from aerospace to microscopy.Traditionally,AO has focused on correcting optical phase aberrations,with recent advances extending to polarisation compensation.However,intensity errors are also prevalent in optical systems,yet effective correction methods are still in their infancy.Here,we introduce a novel AO approach,termed intensity adaptive optics(I-AO),which employs a dual-feedback loop mechanism to first address non-uniform intensity distribution and subsequently compensate for energy loss at the pupil plane.We demonstrate that I-AO can operate in both sensor-based and sensorless formats and validate its feasibility by quantitatively analysing the focus quality of an aberrated system.This technique expands the AO toolkit,paving the way for next-generation AO technology.
文摘In this paper,a method of 3D reconstruction from two images acquired by two panoramic cameras is presented.Firstly,the features of the reconstruction object detected in each image are matched through the DP matching method.Secondly,optical correction is carried out on two cameras,and the internal parameters of panoramic cameras can be calculated.Finally,according to the calibration method,the geometric relationship between corresponding points in space and in two panoramic images is deduced.The results indicate that the method of 3D reconstruction based on two panoramic cameras is simple,and the accuracy can reach 98.82%.
文摘Inverse lithography technology(ILT),also known as pixel-based optical proximity correction(PB-OPC),has shown promising capability in pushing the current 193 nm lithography to its limit.By treating the mask optimization process as an inverse problem in lithography,ILT provides a more complete exploration of the solution space and better pattern fidelity than the traditional edge-based OPC.However,the existing methods of ILT are extremely time-consuming due to the slow convergence of the optimization process.To address this issue,in this paper we propose a support vector machine(SVM)based layout retargeting method for ILT,which is designed to generate a good initial input mask for the optimization process and promote the convergence speed.Supervised by optimized masks of training layouts generated by conventional ILT,SVM models are learned and used to predict the initial pixel values in the‘undefined areas’of the new layout.By this process,an initial input mask close to the final optimized mask of the new layout is generated,which reduces iterations needed in the following optimization process.Manufacturability is another critical issue in ILT;however,the mask generated by our layout retargeting method is quite irregular due to the prediction inaccuracy of the SVM models.To compensate for this drawback,a spatial filter is employed to regularize the retargeted mask for complexity reduction.We implemented our layout retargeting method with a regularized level-set based ILT(LSB-ILT)algorithm under partially coherent illumination conditions.Experimental results show that with an initial input mask generated by our layout retargeting method,the number of iterations needed in the optimization process and runtime of the whole process in ILT are reduced by 70.8%and 69.0%,respectively.
