Systemically angular and planar transport investigations are performed in layered antiferromagnetic(AF)V_(5)S_(8).In this AF system,obvious anomalous Hall effect(AHE)is observed with a large Hall angle of 0.1 compared...Systemically angular and planar transport investigations are performed in layered antiferromagnetic(AF)V_(5)S_(8).In this AF system,obvious anomalous Hall effect(AHE)is observed with a large Hall angle of 0.1 compared to that in ferromagnetic(FM)system.It can persist to the temperatures above AF transition and exhibit strong angular field dependence.The phase diagram reveals various magnetic states by rotating the applied field.By analyzing the anisotropic transport behavior,magnon contributions are revealed and exhibit obvious angular dependence with a spin-flop vanishing line.The observed prominent planar Hall effect and anisotropic magnetoresisitivity exhibit two-fold systematical angular dependent oscillations.These behaviors are attributed to the scattering from spin–orbital coupling instead of nontrivial topological origin.Our results reveal anisotropic interactions of magnetism and electron in V5S8,suggesting potential opportunities for the AF spintronic sensor and devices.展开更多
Planar sliding is one of the frequently observed types of failure in rock slopes.Kinematic analysis is a classic and widely used method to examine the potential failure modes in rock masses.The accuracy of planar slid...Planar sliding is one of the frequently observed types of failure in rock slopes.Kinematic analysis is a classic and widely used method to examine the potential failure modes in rock masses.The accuracy of planar sliding kinematic analysis is significantly influenced by the value assigned to the lateral limit angleγlim.However,the assignment ofγlim is currently used generally based on an empirical criterion.This study aims to propose an approach for determining the value ofγlim in deterministic and probabilistic kinematic planar sliding analysis.A new perspective is presented to reveal thatγlim essentially influences the probability of forming a potential planar sliding block.The procedure to calculate this probability is introduced using the block theory method.It is found that the probability is correlated with the number of discontinuity sets presented in rock masses.Thus,different values ofγlim for rock masses with different sets of discontinuities are recommended in both probabilistic and deterministic planar sliding kinematic analyses;whereas a fixed value ofγlim is commonly assigned to different types of rock masses in traditional method.Finally,an engineering case was used to compare the proposed and traditional kinematic analysis methods.The error rates of the traditional method vary from 45%to 119%,while that of the proposed method ranges between 1%and 17%.Therefore,it is likely that the proposed method is superior to the traditional one.展开更多
Due to the importance of vibration effects on the functional accuracy of mechanical systems,this research aims to develop a precise model of a nonlinearly vibrating single-link mobile flexible manipulator.The manipula...Due to the importance of vibration effects on the functional accuracy of mechanical systems,this research aims to develop a precise model of a nonlinearly vibrating single-link mobile flexible manipulator.The manipulator consists of an elastic arm,a rotary motor,and a rigid carrier,and undergoes general in-plane rigid body motion along with elastic transverse deformation.To accurately model the elastic behavior,Timoshenko’s beam theory is used to describe the flexible arm,which accounts for rotary inertia and shear deformation effects.By applying Newton’s second law,the nonlinear governing equations of motion for the manipulator are derived as a coupled system of ordinary differential equations(ODEs)and partial differential equations(PDEs).Then,the assumed mode method(AMM)is used to solve this nonlinear system of governing equations with appropriate shape functions.The assumed modes can be obtained after solving the characteristic equation of a Timoshenko beam with clamped boundary conditions at one end and an attached mass/inertia at the other.In addition,the effect of the transverse vibration of the inextensible arm on its axial behavior is investigated.Despite the axial rigidity,the effect makes the rigid body dynamics invalid for the axial behavior of the arm.Finally,numerical simulations are conducted to evaluate the performance of the developed model,and the results are compared with those obtained by the finite element approach.The comparison confirms the validity of the proposed dynamic model for the system.According to the mentioned features,this model can be reliable for investigating the system’s vibrational behavior and implementing vibration control algorithms.展开更多
In order to get atomic smooth rigid disk substrate surface, ultra-fined alumina slurry and nanometer silica slurry are prepared, and two steps chemical-mechanical polishing （CMP） of rigid disk substrate in the two s...In order to get atomic smooth rigid disk substrate surface, ultra-fined alumina slurry and nanometer silica slurry are prepared, and two steps chemical-mechanical polishing （CMP） of rigid disk substrate in the two slurries are studied. The results show that, during the first step CMP in the alumina slurry, a high material removal rate is reached, and the average roughness （Ra） and the average waviness （Wa） of the polished surfaces can be decreased from previous 1.4 nm and 1.6 nm to about 0.6 nm and 0.7 nm, respectively. By using the nanometer silica slurry and optimized polishing process parameters in the second step CMP, the Ra and the Wa of the polished surfaces can be further reduced to 0.038 nm and 0.06 am, respectively. Atom force microscopy （AFM） analysis shows that the final polished surfaces are ultra-smooth without micro-defects.展开更多
Diamond pad conditioners can determine the efficiency of CMP processes and the quality of polished wafers.The polishing rate of a wafer is dependent on the amplitude(height) of pad asperities.The polishing uniformity ...Diamond pad conditioners can determine the efficiency of CMP processes and the quality of polished wafers.The polishing rate of a wafer is dependent on the amplitude(height) of pad asperities.The polishing uniformity is controlled by the frequency(density) of such asperities.Current diamond pad conditioners cannot dress the pad to produce microns sized asperities at high density.This is because the tips of diamond grits cannot be leveled to the same height so the grooved pad top is uneven with excessive asperities that may ruin the wafer and under sized asperities that is easily glazed. New designs of diamond pad conditioners have markedly improved the leveling of diamond tips.Organic diamond disks(ODD) are manufactured by reverse casting of polymers.Due to the uniform spacing of diamond grits and their controlled tip heights,none of the diamond grits will be overly stressed.Moreover,all diamond grits are sharing the dressing work.Consequently,the number of working grits of ODD is significantly higher than conventional designs.Moreover,because no diamond will cut pad unecessarily,the pad life is greatly lengthened.Furthermore,due to the uniform distribution of pad asperities,the slurry will be held efficiently so the run off is avoided.As a result,the slurry usage is reduced.ODD is therefore a significant savor of CMP consumables for semiconductor manufacture.展开更多
In the paper, chemical mechanical planarization （CMP） of Ge2 Sb2Te5 （GST） is investigated using IC 1010 and Politex reg pads in acidic slurry. For the CMP with blank wafer, it is found that the removal rate （RR）...In the paper, chemical mechanical planarization （CMP） of Ge2 Sb2Te5 （GST） is investigated using IC 1010 and Politex reg pads in acidic slurry. For the CMP with blank wafer, it is found that the removal rate （RR） of GST increases with the increase of pressure for both pads, but the RR of GST polished using IC 1010 is far more than that of Politex reg. To check the surface defects, GST film is observed with an optical microscope （OM） and scanning electron microscope （SEM）. For the CMP with Politex reg, many spots are observed on the surface of the blank wafer with OM, but no obvious spots are observed with SEM. With regard to the patterned wafer, a few stains are observed on the GST cell, but many residues are found on other area with OM. However, from SEM results, a few residues are observed on the GST cell, more dielectric loss is revealed about the trench structure. For the CMP with IC1010, the surface of the polished blank wafer suffers serious scratches found with both OM and SEM, which may result from a low hardness of GST, compared with those of IC1010 and abrasives. With regard to the patterned wafer, it can achieve a clean surface and almost no scratches are observed with OM, which may result from the high-hardness SiO2 film on the surface, not from the soft GST film across the whole wafer. From the SEM results, a clean interface and no residues are observed on the GST surface, and less dielectric loss is revealed. Compared with Politex reg, the patterned wafer can achieve a good performance after CMP using IC1010.展开更多
Presently, the products of functional ceramic are widely applied in the light & mechatronics fields such as communication, aeronautic and astronautic engineering, military affairs and home-use electrical appliance...Presently, the products of functional ceramic are widely applied in the light & mechatronics fields such as communication, aeronautic and astronautic engineering, military affairs and home-use electrical appliance etc. It’s performance of working is mainly determined by the physical performance of the surface. And therefore the roughness and the affected layer’s depth of the final processing surface have a direct influence to the performance of the device. It is obvious that how to guarantee the processing quality of functional ceramic is a kernel problem whether it can achieve the purpose of application or not. Ultra-precision planarization is usually as the final processing method of functional ceramic substrates, and the mirror surface of Ra 0.01～0.002 μm can be obtained by ultra-precision polishing. For the ultra-precision planarization processing of functional ceramic material, simplex chemical or mechanical polishing method is very difficult to achieve the technic demands, and furthermore various defects of processing exist in the surface of crystal after planarization. However, chemical mechanical planarization (CMP) which has emerged recently as a new indispensable processing technique for higher degree planarization of functional ceramic is be able to satisfy the processing requests from the aspects of processing performance and rate. The current paper systematically introduces the processing course of functional ceramic by using chemical mechanical planarization. In addition, material removal mechanism is analyzed, and the choosing of processing conditions and components and effect of polishing slurry are discussed. Then the present research status and development trend of CMP technology for functional ceramic are discussed. Finally the current existing main questions and their solutions are presented.展开更多
基金Project supported by the open research fund of Songshan Lake Materials Laboratory(Grant No.2021SLABFN11)the National Natural Science Foundation of China(Grant Nos.U2130101 and 92165204)+5 种基金Natural Science Foundation of Guangdong Province(Grant No.2022A1515010035)Guangzhou Basic and Applied Basic Research Foundation(Grant No.202201011798)the Open Project of Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(Grant No.2022B1212010008)the Open Project of Key Laboratory of Optoelectronic Materials and Technologies(Grant No.OEMT-2023-ZTS-01)the National Key R&D Program of China(Grant Nos.2023YFF0718400 and 2023YFA1406500)(national)college students innovation and entrepreneurship training program,Sun Yat-sen University(Grant No.202310359).
文摘Systemically angular and planar transport investigations are performed in layered antiferromagnetic(AF)V_(5)S_(8).In this AF system,obvious anomalous Hall effect(AHE)is observed with a large Hall angle of 0.1 compared to that in ferromagnetic(FM)system.It can persist to the temperatures above AF transition and exhibit strong angular field dependence.The phase diagram reveals various magnetic states by rotating the applied field.By analyzing the anisotropic transport behavior,magnon contributions are revealed and exhibit obvious angular dependence with a spin-flop vanishing line.The observed prominent planar Hall effect and anisotropic magnetoresisitivity exhibit two-fold systematical angular dependent oscillations.These behaviors are attributed to the scattering from spin–orbital coupling instead of nontrivial topological origin.Our results reveal anisotropic interactions of magnetism and electron in V5S8,suggesting potential opportunities for the AF spintronic sensor and devices.
基金funded by National Natural Science Foundation,China(Grant Nos.41972264 and 42207214)Zhejiang Provincial Natural Science Foundation,China(Grant No.LR22E080002).
文摘Planar sliding is one of the frequently observed types of failure in rock slopes.Kinematic analysis is a classic and widely used method to examine the potential failure modes in rock masses.The accuracy of planar sliding kinematic analysis is significantly influenced by the value assigned to the lateral limit angleγlim.However,the assignment ofγlim is currently used generally based on an empirical criterion.This study aims to propose an approach for determining the value ofγlim in deterministic and probabilistic kinematic planar sliding analysis.A new perspective is presented to reveal thatγlim essentially influences the probability of forming a potential planar sliding block.The procedure to calculate this probability is introduced using the block theory method.It is found that the probability is correlated with the number of discontinuity sets presented in rock masses.Thus,different values ofγlim for rock masses with different sets of discontinuities are recommended in both probabilistic and deterministic planar sliding kinematic analyses;whereas a fixed value ofγlim is commonly assigned to different types of rock masses in traditional method.Finally,an engineering case was used to compare the proposed and traditional kinematic analysis methods.The error rates of the traditional method vary from 45%to 119%,while that of the proposed method ranges between 1%and 17%.Therefore,it is likely that the proposed method is superior to the traditional one.
文摘Due to the importance of vibration effects on the functional accuracy of mechanical systems,this research aims to develop a precise model of a nonlinearly vibrating single-link mobile flexible manipulator.The manipulator consists of an elastic arm,a rotary motor,and a rigid carrier,and undergoes general in-plane rigid body motion along with elastic transverse deformation.To accurately model the elastic behavior,Timoshenko’s beam theory is used to describe the flexible arm,which accounts for rotary inertia and shear deformation effects.By applying Newton’s second law,the nonlinear governing equations of motion for the manipulator are derived as a coupled system of ordinary differential equations(ODEs)and partial differential equations(PDEs).Then,the assumed mode method(AMM)is used to solve this nonlinear system of governing equations with appropriate shape functions.The assumed modes can be obtained after solving the characteristic equation of a Timoshenko beam with clamped boundary conditions at one end and an attached mass/inertia at the other.In addition,the effect of the transverse vibration of the inextensible arm on its axial behavior is investigated.Despite the axial rigidity,the effect makes the rigid body dynamics invalid for the axial behavior of the arm.Finally,numerical simulations are conducted to evaluate the performance of the developed model,and the results are compared with those obtained by the finite element approach.The comparison confirms the validity of the proposed dynamic model for the system.According to the mentioned features,this model can be reliable for investigating the system’s vibrational behavior and implementing vibration control algorithms.
基金This project is supported by National Basic Research Program of China (973 Program, N0.2003CB716201)National Natural Science Foundation of China (No.50575131)Science Foundation of Shanghai Municipal Commission of Science and Technology, China(No.0452nm013).
文摘In order to get atomic smooth rigid disk substrate surface, ultra-fined alumina slurry and nanometer silica slurry are prepared, and two steps chemical-mechanical polishing （CMP） of rigid disk substrate in the two slurries are studied. The results show that, during the first step CMP in the alumina slurry, a high material removal rate is reached, and the average roughness （Ra） and the average waviness （Wa） of the polished surfaces can be decreased from previous 1.4 nm and 1.6 nm to about 0.6 nm and 0.7 nm, respectively. By using the nanometer silica slurry and optimized polishing process parameters in the second step CMP, the Ra and the Wa of the polished surfaces can be further reduced to 0.038 nm and 0.06 am, respectively. Atom force microscopy （AFM） analysis shows that the final polished surfaces are ultra-smooth without micro-defects.
文摘Diamond pad conditioners can determine the efficiency of CMP processes and the quality of polished wafers.The polishing rate of a wafer is dependent on the amplitude(height) of pad asperities.The polishing uniformity is controlled by the frequency(density) of such asperities.Current diamond pad conditioners cannot dress the pad to produce microns sized asperities at high density.This is because the tips of diamond grits cannot be leveled to the same height so the grooved pad top is uneven with excessive asperities that may ruin the wafer and under sized asperities that is easily glazed. New designs of diamond pad conditioners have markedly improved the leveling of diamond tips.Organic diamond disks(ODD) are manufactured by reverse casting of polymers.Due to the uniform spacing of diamond grits and their controlled tip heights,none of the diamond grits will be overly stressed.Moreover,all diamond grits are sharing the dressing work.Consequently,the number of working grits of ODD is significantly higher than conventional designs.Moreover,because no diamond will cut pad unecessarily,the pad life is greatly lengthened.Furthermore,due to the uniform distribution of pad asperities,the slurry will be held efficiently so the run off is avoided.As a result,the slurry usage is reduced.ODD is therefore a significant savor of CMP consumables for semiconductor manufacture.
基金Project supported by the National Basic Research Program of China(Grant Nos.2010CB934300,2013CBA01900,2011CBA00607,and 2011CB9328004)the "Strategic Priority Research Program" of the Chinese Academy of Sciences(Grant No.XDA09020402)+2 种基金the Fund from the Science and Technology Council of Shanghai,China(Grant No.13DZ2295700)the Science Fund from the Chinese Academy of Sciences(Grant No.20110490761)the National Natural Science Foundation of China(Grant Nos.61076121,61176122,and 61106001)
文摘In the paper, chemical mechanical planarization （CMP） of Ge2 Sb2Te5 （GST） is investigated using IC 1010 and Politex reg pads in acidic slurry. For the CMP with blank wafer, it is found that the removal rate （RR） of GST increases with the increase of pressure for both pads, but the RR of GST polished using IC 1010 is far more than that of Politex reg. To check the surface defects, GST film is observed with an optical microscope （OM） and scanning electron microscope （SEM）. For the CMP with Politex reg, many spots are observed on the surface of the blank wafer with OM, but no obvious spots are observed with SEM. With regard to the patterned wafer, a few stains are observed on the GST cell, but many residues are found on other area with OM. However, from SEM results, a few residues are observed on the GST cell, more dielectric loss is revealed about the trench structure. For the CMP with IC1010, the surface of the polished blank wafer suffers serious scratches found with both OM and SEM, which may result from a low hardness of GST, compared with those of IC1010 and abrasives. With regard to the patterned wafer, it can achieve a clean surface and almost no scratches are observed with OM, which may result from the high-hardness SiO2 film on the surface, not from the soft GST film across the whole wafer. From the SEM results, a clean interface and no residues are observed on the GST surface, and less dielectric loss is revealed. Compared with Politex reg, the patterned wafer can achieve a good performance after CMP using IC1010.
文摘Presently, the products of functional ceramic are widely applied in the light & mechatronics fields such as communication, aeronautic and astronautic engineering, military affairs and home-use electrical appliance etc. It’s performance of working is mainly determined by the physical performance of the surface. And therefore the roughness and the affected layer’s depth of the final processing surface have a direct influence to the performance of the device. It is obvious that how to guarantee the processing quality of functional ceramic is a kernel problem whether it can achieve the purpose of application or not. Ultra-precision planarization is usually as the final processing method of functional ceramic substrates, and the mirror surface of Ra 0.01～0.002 μm can be obtained by ultra-precision polishing. For the ultra-precision planarization processing of functional ceramic material, simplex chemical or mechanical polishing method is very difficult to achieve the technic demands, and furthermore various defects of processing exist in the surface of crystal after planarization. However, chemical mechanical planarization (CMP) which has emerged recently as a new indispensable processing technique for higher degree planarization of functional ceramic is be able to satisfy the processing requests from the aspects of processing performance and rate. The current paper systematically introduces the processing course of functional ceramic by using chemical mechanical planarization. In addition, material removal mechanism is analyzed, and the choosing of processing conditions and components and effect of polishing slurry are discussed. Then the present research status and development trend of CMP technology for functional ceramic are discussed. Finally the current existing main questions and their solutions are presented.
