In this review,we describe our research on the development of the 13.5 nm coherent microscope using high-order harmonics for the mask inspection of extreme ultraviolet(EUV)lithography.EUV lithography is a game-changin...In this review,we describe our research on the development of the 13.5 nm coherent microscope using high-order harmonics for the mask inspection of extreme ultraviolet(EUV)lithography.EUV lithography is a game-changing piece of technology for high-volume manufacturing of commercial semiconductors.Many top manufacturers apply EUV technology for fabricating the most critical layers of 7 nm chips.Fabrication and inspection of defect-free masks,however,still remain critical issues in EUV technology.Thus,in our pursuit for a resolution,we have developed the coherent EUV scatterometry microscope(CSM)system with a synchrotron radiation(SR)source to establish the actinic metrology,along with inspection algorithms.The intensity and phase images of patterned EUV masks were reconstructed from diffraction patterns using ptychography algorithms.To expedite the practical application of the CSM,we have also developed a standalone CSM,based on high-order harmonic generation,as an alternative to the SR-CSM.Since the application of a coherent 13.5 nm harmonic enabled the production of a high contrast diffraction pattern,diffraction patterns of sub-100 ns size defects in a 2D periodic pattern mask could be observed.Reconstruction of intensity and phase images from diffraction patterns were also performed for a periodic line-and-space structure,an aperiodic angle edge structure,as well as a cross pattern in an EUV mask.展开更多
Scatterometry is a well-established,fast and precise optical metrology method used for the characterization of sub-lambda periodic features.The Fourier scatterometry method,by analyzing the Fourier plane,makes it poss...Scatterometry is a well-established,fast and precise optical metrology method used for the characterization of sub-lambda periodic features.The Fourier scatterometry method,by analyzing the Fourier plane,makes it possible to collect the angle-resolved diffraction spectrum without any mechanical scanning.To improve the depth sensitivity of this method,we combine it with white light interferometry.We show the exemplary application of the method on a silicon line grating.To characterize the sub-lambda features of the grating structures,we apply a model-based reconstruction approach by comparing simulated and measured spectra.All simulations are based on the rigorous coupled-wave analysis method.展开更多
Smaller and more complex three-dimensional periodic nanostructures are part of the next generation of integrated electronic circuits.Additionally,decreasing the dimensions of nanostructures increases the effect of lin...Smaller and more complex three-dimensional periodic nanostructures are part of the next generation of integrated electronic circuits.Additionally,decreasing the dimensions of nanostructures increases the effect of line-edge roughness on the performance of the nanostructures.Efficient methods for characterizing three-dimensional nanostructures are required for process control.Here,extreme-ultraviolet(EUV)scatterometry is exploited for the analysis of line-edge roughness from periodic nanostructures.In line with previous observations,differences are observed between line edge and line width roughness.The angular distribution of the diffuse scattering is an interplay of the line shape,the height of the structure,the roughness along the line,and the correlation between the lines.Unfortunately,existing theoretical methods for characterizing nanostructures using scatterometry do not cover all these aspects.Examples are shown here and the demands for future development of theoretical approaches for computing the angular distribution of the scattered X-rays are discussed.展开更多
The sub-atomic precision of molecular beam epitaxy(MBE)allows for highly flexible elemental doping in nanowires(NWs).Optimizing doping quality for specific elements requires a comprehensive understanding of the relati...The sub-atomic precision of molecular beam epitaxy(MBE)allows for highly flexible elemental doping in nanowires(NWs).Optimizing doping quality for specific elements requires a comprehensive understanding of the relationship between process parameters and doping concentrations.This necessitates in-situ monitoring of the doping process to define the corresponding process window.However,the reflection high-energy electron diffraction(RHEED)technique,commonly used during MBE growth,has limited sensitivity to atomic arrangement changes caused by doping and is primarily capable of monitoring the structural quality of the sample.To address this limitation,we propose a nanowire doping concentration measurement method based on angle-resolved scatterometry(ARS).This method captures scattering information across the full angular range of NWs,allowing for high-resolution measurement of doping concentration.Using GaN NWs and AlN films doped with Si as a case study,we measured the Si concentration at different doping temperatures.The results demonstrate that the proposed method achieves a doping concentration resolution of 0.01%and 0.06%within the investigated temperature range.Furthermore,we employed deep learning to establish the relationship between angle-resolved reflectivity and nominal doping concentration.The predictive results indicate that the measurement error is maintained below 0.027%.We also validated the robustness of the method across multiple measurement wavelengths and explored the feasibility of using reduced angle reflectance for neural network training.This work paves the way for in-situ monitoring of nanowire doping processes through ARS,significantly enhancing doping control precision in MBE growth.展开更多
A physical model for simulating overlay metrology employing diffraction based overlay(DBO)principles is built.It can help to optimize the metrology wavelength selection in DBO.Simulation result of DBO metrology with a...A physical model for simulating overlay metrology employing diffraction based overlay(DBO)principles is built.It can help to optimize the metrology wavelength selection in DBO.Simulation result of DBO metrology with a model based on the finite-difference time-domain(FDTD)method is presented.A common case(bottom mark asymmetry)in which error signals are always induced in DBO measurement due to the process imperfection were discussed.The overlay sensitivity of the DBO measurement across the visible illumination spectrum has been performed and compared.After adjusting the model parameters compatible with the actual measurement conditions,the metrology wavelengths which provide the accuracy and robustness of DBO measurement can be optimized.展开更多
文摘In this review,we describe our research on the development of the 13.5 nm coherent microscope using high-order harmonics for the mask inspection of extreme ultraviolet(EUV)lithography.EUV lithography is a game-changing piece of technology for high-volume manufacturing of commercial semiconductors.Many top manufacturers apply EUV technology for fabricating the most critical layers of 7 nm chips.Fabrication and inspection of defect-free masks,however,still remain critical issues in EUV technology.Thus,in our pursuit for a resolution,we have developed the coherent EUV scatterometry microscope(CSM)system with a synchrotron radiation(SR)source to establish the actinic metrology,along with inspection algorithms.The intensity and phase images of patterned EUV masks were reconstructed from diffraction patterns using ptychography algorithms.To expedite the practical application of the CSM,we have also developed a standalone CSM,based on high-order harmonic generation,as an alternative to the SR-CSM.Since the application of a coherent 13.5 nm harmonic enabled the production of a high contrast diffraction pattern,diffraction patterns of sub-100 ns size defects in a 2D periodic pattern mask could be observed.Reconstruction of intensity and phase images from diffraction patterns were also performed for a periodic line-and-space structure,an aperiodic angle edge structure,as well as a cross pattern in an EUV mask.
基金We are thankful for the technical support given by Thomas Schoder.This work was supported by the German DFG-funded priority program(SPP1327)on‘Optically generated sub-100 nm structures for technical and bio-medical applications’within the subproject‘Development of a functional sub-100 nm 3D two-photon polymerization technique and optical characterization methods’and the DFG project‘Inverse-source and inverse-diffraction problems in photonics(OS111/32-1).’。
文摘Scatterometry is a well-established,fast and precise optical metrology method used for the characterization of sub-lambda periodic features.The Fourier scatterometry method,by analyzing the Fourier plane,makes it possible to collect the angle-resolved diffraction spectrum without any mechanical scanning.To improve the depth sensitivity of this method,we combine it with white light interferometry.We show the exemplary application of the method on a silicon line grating.To characterize the sub-lambda features of the grating structures,we apply a model-based reconstruction approach by comparing simulated and measured spectra.All simulations are based on the rigorous coupled-wave analysis method.
基金funding from the Electronic Component Systems for European Leadership Joint Undertaking under grant agreement No 826589|MADEin4This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme and The Netherlands,France,Belgium,Germany,Czech Republic,Austria,Hungary,and IsraelOpen Access funding enabled and organized by Projekt DEAL.
文摘Smaller and more complex three-dimensional periodic nanostructures are part of the next generation of integrated electronic circuits.Additionally,decreasing the dimensions of nanostructures increases the effect of line-edge roughness on the performance of the nanostructures.Efficient methods for characterizing three-dimensional nanostructures are required for process control.Here,extreme-ultraviolet(EUV)scatterometry is exploited for the analysis of line-edge roughness from periodic nanostructures.In line with previous observations,differences are observed between line edge and line width roughness.The angular distribution of the diffuse scattering is an interplay of the line shape,the height of the structure,the roughness along the line,and the correlation between the lines.Unfortunately,existing theoretical methods for characterizing nanostructures using scatterometry do not cover all these aspects.Examples are shown here and the demands for future development of theoretical approaches for computing the angular distribution of the scattered X-rays are discussed.
基金supported by the National Natural Science Foundation of China under Grant No.62204173Hainan Province Science and Technology Special Fund under Grant ZDYF2023GXJS005+7 种基金Collaborative Innovation Center of Information Technology,Hainan University(XTCX2022XXB03)Hubei Key Laboratory of Electronic Manufacturing and Packaging Integration(Wuhan University)(Grant No.EMPI2024022)Major Program(JD)of Hubei Province(No.2023BAA008)Jiangsu Province Engineering Research Center of Integrated Circuit Advanced Assembly and Test,China(No.NTIKFJJ202305)the Open Fund Project of the State Key Laboratory of Intelligent Vehicle Safety Technology(IVSTSKL-202308)Hainan University Research Initiation Fund Project(XJ2400011663)The National Key R&D Program of China(2024YFC2816900)The Science and Technology special fund of Hainan Province NO.ZDYF2024GXJS303.
文摘The sub-atomic precision of molecular beam epitaxy(MBE)allows for highly flexible elemental doping in nanowires(NWs).Optimizing doping quality for specific elements requires a comprehensive understanding of the relationship between process parameters and doping concentrations.This necessitates in-situ monitoring of the doping process to define the corresponding process window.However,the reflection high-energy electron diffraction(RHEED)technique,commonly used during MBE growth,has limited sensitivity to atomic arrangement changes caused by doping and is primarily capable of monitoring the structural quality of the sample.To address this limitation,we propose a nanowire doping concentration measurement method based on angle-resolved scatterometry(ARS).This method captures scattering information across the full angular range of NWs,allowing for high-resolution measurement of doping concentration.Using GaN NWs and AlN films doped with Si as a case study,we measured the Si concentration at different doping temperatures.The results demonstrate that the proposed method achieves a doping concentration resolution of 0.01%and 0.06%within the investigated temperature range.Furthermore,we employed deep learning to establish the relationship between angle-resolved reflectivity and nominal doping concentration.The predictive results indicate that the measurement error is maintained below 0.027%.We also validated the robustness of the method across multiple measurement wavelengths and explored the feasibility of using reduced angle reflectance for neural network training.This work paves the way for in-situ monitoring of nanowire doping processes through ARS,significantly enhancing doping control precision in MBE growth.
基金supported by the National Science and Technology Major Project of China (Grant No. 2016ZX02301001)
文摘A physical model for simulating overlay metrology employing diffraction based overlay(DBO)principles is built.It can help to optimize the metrology wavelength selection in DBO.Simulation result of DBO metrology with a model based on the finite-difference time-domain(FDTD)method is presented.A common case(bottom mark asymmetry)in which error signals are always induced in DBO measurement due to the process imperfection were discussed.The overlay sensitivity of the DBO measurement across the visible illumination spectrum has been performed and compared.After adjusting the model parameters compatible with the actual measurement conditions,the metrology wavelengths which provide the accuracy and robustness of DBO measurement can be optimized.
