Multiscale Investigation On The Heat Transfer And Mechanical Behavior Of Interface Structures In Microelectronic Devices

Nowadays, the electronic devices are widely used in the fields of aerospace, military, civil and other electronic products. Coincident with the advancement of micro/nano design and manufacturing technologies, the micro-devices become more and more high density, microminiaturization and functional systemic. The interfacial strutures consist of different materials and some discontinuous structures become more complex, which is widely used in IC/MEMS devices. A lot of experiments show that the reliability of interfacial structures is one of the most important strutures which affect the performance of the whole device or system. Almost all of the deformations and defects always appear in the interface. Hence, the investigation of the interfical heat transfer and mechanical properties of interface structure is very useful for the designing and manufacturing of microelectronic. The size of the interfacial structures is in the nanoscale due to the development of manufacturing process. The size effect of the interface becomes more and more obvious. At this moment, the traditional modeling and analysis methods are not suitable any more in this nanoscale situation. The investigation on the heat transfer mechanism in the interfacial structure has been a main difficulty for microelectronic densign and manufacturing. It is a potential method to analyze the interfacial problems that how to build a multiscle analysis method by considering the advantages of different methods under different scales.The interfacial heat transfer mechanism and mechanical properties of the interface sturctures in the mciro/nano electronic manufacturing are investigated based on the numerical and experimental methods in this paper. On the one hand, the multiscale model and analysis method is put forward based on the molecular dynamic, interface stress element and finite element methods in this paper. And it is used to analyze the mechanical and heat transfer of interfacial structure in one dimensional. On the other hand, the different interface samples are prepared by the magnetron sputtering method. And then, the thermal porperties and mechanical charateristics of the interface structure are investigated based on the experimental methods (3co transient heat reflection method and nanoindentation). The main research and results in this paper are included as follows,Firstly, a multiscale method based on MD-ISE-FE is put forword to investigate the charateristics from the nanoscal to macroscale in this paper, which is built by the design of different handshake regions conneced the different methods in different scales. In the handshake regions of ISE and FE, the stiffness matrixs and load matrixs of ISE and FE are coupled dicretly; meanwhile, the mapping operator methods and interpolation algorithm are used to connect the atoms and the interfacial element in the MD and ISE handshake regio. The Hamiltonian is used to describe the engery of the handshake regions. The multiscale model is solved based on the sequence coupling method. The one dimensional heat transfer and tensile are calclulated based on the multiscale model and the sequence coupling method. Comparing with some references, the results prove that the MD-ISE-FE multiscale modeling and analysis method is feasible and useful for understanding the interfacial reliability. The mechanical and heat transfer of interfacial structure in one dimensional have been investigated based on MD-ISE-FE multiscale method, the results show that the charateristics of heat transfer and mechanical of interface structure consisting of the same materials or similar materials are better than that of interface structure consisting of dissimilar mateirals.Secondly, the thermal performances of the interface structure are investigated under differernt temperatures. The interfacial diffusion thickness of interface structure increases with the temperature increasing in nanoscale (Especially, the percentage of the interfacial diffusion thickness in the whole interface thickness is about5.19%when the tempartue is300K.). It indicates that the phonon scattering becomes more and more serious with the temeperature increasing, which also reduces the phonon coincident degree in the interfacial heat transfer. All these fators of phonon would reduce the interfacial thermal conductivity. But the results in this paper show that the phonon coincident degree decreases with the temperature increasing, while, the change of the thermal conductivity increases firstly and then to decrease. The interfacial heat transfer mechanism of the interface is explained from the coupling of the phonon and electron. It is found that the effciency of eletron heat transfer is enhanced with the termperature increasing (lower than the recrystallization temperature). The results prove that the micro/nanocscale heat transfer mechanism of the interface structure is the coupling results of phonon and eletron. And it is found that the electron is the main fator in the interfacial heat transfer compared with Phonon.Finally, the thermal properties (thermal resistance and thermal conductivity) and mechanical charateristcs (Elastic modulus and Hardness) of the interface structures are investigated based on the magnetron sputtering, transient heat reflection method and nanoindentation technology. On the one hand, the mechanical charateristics (Elastic modulus and Hardness) of the interface are studied in this paper. Some different interface structures (Cu/Cu and Cu/Al) are built for investigation. The stress-strain relationships of different interfaces are systemically investigated based on the tensile test simulation of the interface. It is found that the stress-strain curve of the diffusion interface is much smoother than that of the ideal interface structure consisting of different materials. The adhension force of the interface reduces in the metallic interface which maybe be caused by the brittleness of the intermetallic compound (IMC) generated in the diffusion interface. The IMC is also one of the most important reasons caused the crack in the interface. On the other hand, the sputtering rate is studied under different powers and different magnetron sputtering methods. The results show that the sputtering rate in the DC (Direct Current) magnetron sputtering is about ten times faster than that in the RF (Radio Frequecny) magnetron sputtering. The heat transfer parameters (thermal conductivity) of the interface samples are tested by using the3ω transient heat reflection method, the thermal conductivity increases with the thickness increasing. Meanwhile, the mechanical charateristics of the interface structure are tested based on the nanoindentation technology. It is foud that the elastic modulus and hardness of the interface reduce with the increase of the indentation depth. This phenomenon is caused by the growing mechanism in the sputtering process. In the films magnetron sputtering process, the film always start from scratch, and from thin to thick. In other words, the random accumulation is always in the begining, after that, the orderly nucleating growth and formation of crystal structure start in the next. There are lots of defects in the random accumulation step, which reduces the density in the beginning. It explains the phenomenon that the elastic modulus and hardness reduce with the increase of the indentation depth in the nanoindentation experiment.The aboved investigations not only systemically studied on the multiscale numerical calculation, but also investigated the interfacial heat transfer and mechanical characteristic of the interface structure on numerical and experimental methods, which is useful for understanding the heat transfer mechanism in the dissimilar materials interface structure. And also implies a potential multiscale method for analyzing the interface performance and designing the interface in the micro/nano manufacturing.