First-Principle Calculation Of SiC/Filler Metal Interface Model

Because of their good mechanical properties and high temperature resistance,SiC ceramics can work normally in many extreme situations,and are widely used in various hightemperature semiconductor fields.Therefore,many research institutions have due to its low tensile strength during brazing,the strength of SiC ceramics at the solder joints is difficult to guarantee,and at the same time,it is suitable for brazing materials and welding on the micron size.There are few studies on the bonding properties of materials.In this paper,under the guidance of the first-principle theoretical basis,this paper mainly studies the interface combination of Al/4H-SiC,Zn/4H-SiC,Sn/4H-SiC,Sn-Zn/4H-SiC,Zn-5Al/4H-SiC,etc.,respectively for C-termination and Si-termination of 4H-SiC,two methods of end capping are used to ensure the true situation of the cell composite material through convergence calculation.The bond strength is determined by calculating the separation work method,and the nature of the interface formation is analyzed by electronic structure.The following conclusions can be drawn:In the formation of Al/4H-SiC interface,ionic covalent bonds are formed between Al-C,which plays a major role in the axial direction during the formation of the interface.Although there are also metal covalent bonds between Al-Si,but according to the population analysis of the interface can polish that the interaction between Al-Si is much weaker than that between Al-C.In the formation of Zn/4H-SiC interface,according to the electronic structure analysis,the covalent bond formed between Zn-C is the main reason for the formation of the interface,and there is no chemical bond formed between Zn-C in the Si-terminated interface.In the interface of Zn-5Al/4H-SiC,adding Al element to the Zn solder can improve the bonding ability of the interface.It is an element that strengthens the interface.It can be polished according to the interface separation work and population analysis.The bond length of Zn-Si and Zn-C is slightly greater than the length of the Al-C bond indicates that the bonding between Zn-Si and Zn-C is not as good as the bonding strength between Al-C,and the Al-C bonding is the reason for the interface formation.In the formation of the Sn/4H-SiC interface,ionic bonds are formed between Sn-C,and the bonding mode between Sn-Si is a covalent bond,and the bonding strength of Sn-C is higher than that of Sn-Si.In the Sn-Zn/SiC interface,the ionic bond is formed between Sn-Zn/C,and the interaction is greater than the chemical bond strength of Sn-Zn/Si,indicating that Sn-Zn/Si bonding plays a major role in the interface formation.At the same time,when the interface between Sn-Zn and SiC is formed,both the C-terminal separation work and the Si-terminal separation work are smaller than the separation work at the Sn/SiC interface.Based on the results of the simulation calculations,experiments on ultrasonic brazing of SiC ceramics were carried out on Sn-Zn and Zn-5Al respectively.The results show that there is no obvious reaction layer and dissolution layer in the two brazing results,but in Zn-5Al/SiC interface,because Al reacts with O,there will be O reflected in the interface.