The morphology and microstructure of flow pattern defects （FPDs） in lightly boron-doped Czochralski-grown silicon （Cz-Si） crystals were investigated using optical microscopy and atomic force microscopy. The experi...The morphology and microstructure of flow pattern defects （FPDs） in lightly boron-doped Czochralski-grown silicon （Cz-Si） crystals were investigated using optical microscopy and atomic force microscopy. The experimental results showed that the morphology of FPDs was parabola-like with several steps. Single-type and dual-type voids were found on the tip of FPDs and two heaves exist on the left and right sides of the void. All the results have proved that FPDs were void-type defects. These results are very useful to investigate FPDs in Cz-Si wafers further and explain the annihilation of FPDs during high-temperature annealing.展开更多
The defect detection of wafers is an important part of semiconductor manufacturing.The wafer defect map formed from the defects can be used to trace back the problems in the production process and make improvements in...The defect detection of wafers is an important part of semiconductor manufacturing.The wafer defect map formed from the defects can be used to trace back the problems in the production process and make improvements in the yield of wafer manufacturing.Therefore,for the pattern recognition of wafer defects,this paper uses an improved ResNet convolutional neural network for automatic pattern recognition of seven common wafer defects.On the basis of the original ResNet,the squeeze-and-excitation(SE)attention mechanism is embedded into the network,through which the feature extraction ability of the network can be improved,key features can be found,and useless features can be suppressed.In addition,the residual structure is improved,and the depth separable convolution is added to replace the traditional convolution to reduce the computational and parametric quantities of the network.In addition,the network structure is improved and the activation function is changed.Comprehensive experiments show that the precision of the improved ResNet in this paper reaches 98.5%,while the number of parameters is greatly reduced compared with the original model,and has well results compared with the common convolutional neural network.Comprehensively,the method in this paper can be very good for pattern recognition of common wafer defect types,and has certain application value.展开更多
Design patterns are object oriented software design practices for solving common design problems and they affect software quality. In this study, we investigate the relationship of design patterns and software defects...Design patterns are object oriented software design practices for solving common design problems and they affect software quality. In this study, we investigate the relationship of design patterns and software defects in a number of open source software projects. Design pattern instances are extracted from the source code repository of these open source software projects. Software defect metrics are extracted from the bug tracking systems of these projects. Using correlation and regression analysis on extracted data, we examine the relationship between design patterns and software defects. Our findings indicate that there is little correlation between the total number of design pattern instances and the number of defects. However, our regression analysis reveals that individual design pattern instances as a group have strong influences on the number of defects. Furthermore, we find that the number of design pattern instances is positively correlated to defect priority. Individual design pattern instances may have positive or negative impacts on defect priority.展开更多
The morphology and microstructure of flow pattern defects (FPDs) in lightly boron-doped Czochralski-grown silicon (Cz-Si) crystals were investigated using optical microscopy and atomic force microscopy. The experiment...The morphology and microstructure of flow pattern defects (FPDs) in lightly boron-doped Czochralski-grown silicon (Cz-Si) crystals were investigated using optical microscopy and atomic force microscopy. The experimental results showed that the morphology of FPDs was parabola-like with several steps. Single-type and dual-type voids were found on the tip of FPDs and two heaves exist on the left and right sides of the void. All the results have proved that FPDs were void-type defects. These results are very useful to investigate FPDs in Cz-Si wafers further and explain the annihilation of FPDs during high-temperature annealing.展开更多
Spherical nanostructures with striped patterns on the surfaces resembling the essential structures of natural virus particles were constructed through a two-step self-assembly approach of polystyrene-boligo（acrylic a...Spherical nanostructures with striped patterns on the surfaces resembling the essential structures of natural virus particles were constructed through a two-step self-assembly approach of polystyrene-boligo（acrylic acid）（PS-b-oligo-AA） and poly（γ-benzyI L-glutamate）-b-poly（ethylene glycol）（PBLG-bPEG） copolymer mixtures in solution.On the basis of difference in hydrophilicity and self-assembly properties of the two copolymers,the two-step self-assembly process is realized.It was found that PS-boligo-AA copolymers formed spherical aggregates by adding a certain amount of water into polymer solutions in the first step.In the second step,two polymer solutions were mixed and water was further added,inducing the self-assembly of PBLG-b-PEG on the surfaces of PS-b-oligo-AA spheres to form striped patterns.In-depth study was conducted for the indispensable defects of striped patterns which are dislocations and ＋1/2 disclinations.The influencing factors such as the mixing ratio of two copolymers and the added water content in the first step on the morphology and defects of the striped patterns were investigated.This work not only presents an idea to interpret mechanism of the cooperative self-assembly behavior,but also provides an effective approach to construct virus-like particles and other complex structures with controllable morphology.展开更多
The evolution and transition of planar wave trains propagating through defects(obstacles) in an excitable medium are studied. When the frequency of the planar wave trains is increased, three different dynamical regime...The evolution and transition of planar wave trains propagating through defects(obstacles) in an excitable medium are studied. When the frequency of the planar wave trains is increased, three different dynamical regimes,namely fusion, "V" waves, and spiral waves, are observed in turn and the underlying mechanism is discussed. The dynamics is concerned with the shapes of the defects. Circle, triangle, and rectangle defects with different sizes are considered. The increase of pacing frequency broadens the fan-shaped broken region in the behind of a rectangle defect.The increase of width of a triangle defect leads to breakup of wave trains easier while the change of height shows opposite effect, which is presented in a phase diagram. Dynamical comparison on defects with different shapes indicates that the decrease of the defect width along the propagation of wave trains makes the fan-shaped region and the minimal frequency for breakup of spiral both increased.展开更多
During the friction stir welding (FSW), the property of the welding joint is highly affected by the plastic and viscous flow behavior of the softened material. The flow pattern of the welded material was examined thro...During the friction stir welding (FSW), the property of the welding joint is highly affected by the plastic and viscous flow behavior of the softened material. The flow pattern of the welded material was examined through observing the microstrucrural distribution of friction stir welded joints between dissimilar 2024 and 1060 aluminum alloy. The experimental results show that the flow patterns of material at different locations in the weld are different and can be divided into four layers along the thickness direction: surface flow layer influenced by the shoulder of the tool, in which the material tends to flow as integrity; horizontal flow layer influenced by the surface flow layer, in which the material of surface flow layer enters and flows forwards under the advancing force of the tool; vertical flow layer (plastic flow area induced by stirring of the pin), in which the flow pattern is complex and onion rings can often be observed; unstirred bottom layer because of the length of the pin being shorter than the thickness of the plates. The effect of plastic flow on welding quality was further investigated. The study suggests that welding quantity is significantly influenced by the flow pattern and defects always appear in horizontally lamellar flow region because of the complex flow pattern.展开更多
A full-field finite element method （FEM） analysis combined with electronic speckle pattern interferometry （ESPI） measurement was developed to investigate defect evolution in polymer films. Different from the previ...A full-field finite element method （FEM） analysis combined with electronic speckle pattern interferometry （ESPI） measurement was developed to investigate defect evolution in polymer films. Different from the previous reports, which only compare the ESPI experimental and FEM simulated results at several points or lines, herein the full-field FEM results were exported, subtracted with a continuous distribution. By choosing proper parameters and number of substeps, the simulated and experimental results showed excellent correspondence. Furthermore, the displacement fields vertical to the tensional direction were also presented, and the strain field was preliminarily evaluated. The current method of combination of ESPI and FEM allows for capturing the experimental fringe maps to validate and optimize FEM results simulated, and would give a higher security to structural and mechanical analysis of polymeric materials.展开更多
Systems hosting flat bands offer a powerful platform for exploring strong correlation physics.Theoretically,topological degeneracy arising in systems with non-trivial topological orders on periodic manifolds of non-ze...Systems hosting flat bands offer a powerful platform for exploring strong correlation physics.Theoretically,topological degeneracy arising in systems with non-trivial topological orders on periodic manifolds of non-zero genus can generate ideal flat bands.However,experimental realization of such geometrically engineered systems is very difficult.In this work,we demonstrate that flat planes with strategically patterned hole defects can engineer ideal flat bands.We construct two families of models:singular flat band systems where degeneracy is stabilized by non-contractible loop excitations tied to hole defects and perfectly nested van Hove systems where degeneracy arises from line excitations in momentum space.These models circumvent the need for exotic manifolds while retaining the essential features of topological flat bands.By directly linking defect engineering to degeneracy mechanisms,our results establish a scalable framework for experimentally accessible flat band design.展开更多
基金This work was financially supported by the National Natural Science Foundation of China (No. 60076001 and No.50032010), the Natural Science Foundation of Tianjin (No. 043602511) and the Natural Science Foundation of Hebei Province of China (No. E2005000057).
文摘The morphology and microstructure of flow pattern defects （FPDs） in lightly boron-doped Czochralski-grown silicon （Cz-Si） crystals were investigated using optical microscopy and atomic force microscopy. The experimental results showed that the morphology of FPDs was parabola-like with several steps. Single-type and dual-type voids were found on the tip of FPDs and two heaves exist on the left and right sides of the void. All the results have proved that FPDs were void-type defects. These results are very useful to investigate FPDs in Cz-Si wafers further and explain the annihilation of FPDs during high-temperature annealing.
基金supported by the 2021 Annual Scientific Research Funding Project of Liaoning Pro-vincial Department of Education(Nos.LJKZ0535,LJKZ0526)the Natural Science Foundation of Liaoning Province(No.2021-MS-300)。
文摘The defect detection of wafers is an important part of semiconductor manufacturing.The wafer defect map formed from the defects can be used to trace back the problems in the production process and make improvements in the yield of wafer manufacturing.Therefore,for the pattern recognition of wafer defects,this paper uses an improved ResNet convolutional neural network for automatic pattern recognition of seven common wafer defects.On the basis of the original ResNet,the squeeze-and-excitation(SE)attention mechanism is embedded into the network,through which the feature extraction ability of the network can be improved,key features can be found,and useless features can be suppressed.In addition,the residual structure is improved,and the depth separable convolution is added to replace the traditional convolution to reduce the computational and parametric quantities of the network.In addition,the network structure is improved and the activation function is changed.Comprehensive experiments show that the precision of the improved ResNet in this paper reaches 98.5%,while the number of parameters is greatly reduced compared with the original model,and has well results compared with the common convolutional neural network.Comprehensively,the method in this paper can be very good for pattern recognition of common wafer defect types,and has certain application value.
文摘Design patterns are object oriented software design practices for solving common design problems and they affect software quality. In this study, we investigate the relationship of design patterns and software defects in a number of open source software projects. Design pattern instances are extracted from the source code repository of these open source software projects. Software defect metrics are extracted from the bug tracking systems of these projects. Using correlation and regression analysis on extracted data, we examine the relationship between design patterns and software defects. Our findings indicate that there is little correlation between the total number of design pattern instances and the number of defects. However, our regression analysis reveals that individual design pattern instances as a group have strong influences on the number of defects. Furthermore, we find that the number of design pattern instances is positively correlated to defect priority. Individual design pattern instances may have positive or negative impacts on defect priority.
文摘The morphology and microstructure of flow pattern defects (FPDs) in lightly boron-doped Czochralski-grown silicon (Cz-Si) crystals were investigated using optical microscopy and atomic force microscopy. The experimental results showed that the morphology of FPDs was parabola-like with several steps. Single-type and dual-type voids were found on the tip of FPDs and two heaves exist on the left and right sides of the void. All the results have proved that FPDs were void-type defects. These results are very useful to investigate FPDs in Cz-Si wafers further and explain the annihilation of FPDs during high-temperature annealing.
基金supported by the National Natural Science Foundation of China(Nos.21234002,51303055,21474029,and51573049)Support from projects of Shanghai municipality(Nos.15QA1401400 and 13JC1402000)
文摘Spherical nanostructures with striped patterns on the surfaces resembling the essential structures of natural virus particles were constructed through a two-step self-assembly approach of polystyrene-boligo（acrylic acid）（PS-b-oligo-AA） and poly（γ-benzyI L-glutamate）-b-poly（ethylene glycol）（PBLG-bPEG） copolymer mixtures in solution.On the basis of difference in hydrophilicity and self-assembly properties of the two copolymers,the two-step self-assembly process is realized.It was found that PS-boligo-AA copolymers formed spherical aggregates by adding a certain amount of water into polymer solutions in the first step.In the second step,two polymer solutions were mixed and water was further added,inducing the self-assembly of PBLG-b-PEG on the surfaces of PS-b-oligo-AA spheres to form striped patterns.In-depth study was conducted for the indispensable defects of striped patterns which are dislocations and ＋1/2 disclinations.The influencing factors such as the mixing ratio of two copolymers and the added water content in the first step on the morphology and defects of the striped patterns were investigated.This work not only presents an idea to interpret mechanism of the cooperative self-assembly behavior,but also provides an effective approach to construct virus-like particles and other complex structures with controllable morphology.
基金Supported by the Natural Science Foundation of Zhejiang Province under Grant Nos.LQ14A050003 and LR17A050001Zhejiang Province Commonweal Projects under Grant No.GK180906288001China Scholarship Council under Grant No.201708330401
文摘The evolution and transition of planar wave trains propagating through defects(obstacles) in an excitable medium are studied. When the frequency of the planar wave trains is increased, three different dynamical regimes,namely fusion, "V" waves, and spiral waves, are observed in turn and the underlying mechanism is discussed. The dynamics is concerned with the shapes of the defects. Circle, triangle, and rectangle defects with different sizes are considered. The increase of pacing frequency broadens the fan-shaped broken region in the behind of a rectangle defect.The increase of width of a triangle defect leads to breakup of wave trains easier while the change of height shows opposite effect, which is presented in a phase diagram. Dynamical comparison on defects with different shapes indicates that the decrease of the defect width along the propagation of wave trains makes the fan-shaped region and the minimal frequency for breakup of spiral both increased.
基金Project(10577010) supported by the National Natural Science Foundation of China
文摘During the friction stir welding (FSW), the property of the welding joint is highly affected by the plastic and viscous flow behavior of the softened material. The flow pattern of the welded material was examined through observing the microstrucrural distribution of friction stir welded joints between dissimilar 2024 and 1060 aluminum alloy. The experimental results show that the flow patterns of material at different locations in the weld are different and can be divided into four layers along the thickness direction: surface flow layer influenced by the shoulder of the tool, in which the material tends to flow as integrity; horizontal flow layer influenced by the surface flow layer, in which the material of surface flow layer enters and flows forwards under the advancing force of the tool; vertical flow layer (plastic flow area induced by stirring of the pin), in which the flow pattern is complex and onion rings can often be observed; unstirred bottom layer because of the length of the pin being shorter than the thickness of the plates. The effect of plastic flow on welding quality was further investigated. The study suggests that welding quantity is significantly influenced by the flow pattern and defects always appear in horizontally lamellar flow region because of the complex flow pattern.
文摘A full-field finite element method （FEM） analysis combined with electronic speckle pattern interferometry （ESPI） measurement was developed to investigate defect evolution in polymer films. Different from the previous reports, which only compare the ESPI experimental and FEM simulated results at several points or lines, herein the full-field FEM results were exported, subtracted with a continuous distribution. By choosing proper parameters and number of substeps, the simulated and experimental results showed excellent correspondence. Furthermore, the displacement fields vertical to the tensional direction were also presented, and the strain field was preliminarily evaluated. The current method of combination of ESPI and FEM allows for capturing the experimental fringe maps to validate and optimize FEM results simulated, and would give a higher security to structural and mechanical analysis of polymeric materials.
基金supported by the Ministry of Science and Technology(Grant No.2022YFA1403901)the National Natural Science Foundation of China(Grant Nos.12494594,11888101,12174428,and 12504192)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB28000000)the New Cornerstone Investigator Program,the Chinese Academy of Sciences through the Youth Innovation Promotion Association(Grant No.2022YSBR-048)the Shanghai Science and Technology Innovation Action Plan(Grant No.24LZ1400800).
文摘Systems hosting flat bands offer a powerful platform for exploring strong correlation physics.Theoretically,topological degeneracy arising in systems with non-trivial topological orders on periodic manifolds of non-zero genus can generate ideal flat bands.However,experimental realization of such geometrically engineered systems is very difficult.In this work,we demonstrate that flat planes with strategically patterned hole defects can engineer ideal flat bands.We construct two families of models:singular flat band systems where degeneracy is stabilized by non-contractible loop excitations tied to hole defects and perfectly nested van Hove systems where degeneracy arises from line excitations in momentum space.These models circumvent the need for exotic manifolds while retaining the essential features of topological flat bands.By directly linking defect engineering to degeneracy mechanisms,our results establish a scalable framework for experimentally accessible flat band design.
