Study On High Temperature Wetting And Interface Behavior Of Al-Si-X/(Pd-)SiC System

Silicon carbide?SiC?has excellent physical and mechanical properties and is one of the third generation semiconductor materials.In the fabrication of SiC semiconductor devices,some problems,such as surface modification,high-temperature wetting and heterogeneous interfacial bonding,can emerge.Ion implantation is one of the most efficient surface modification process due to a series of advantages,such as which can be carried out at room temperature,with no interface between the implantation layer and ceramic substrate,and the concentration-depth distribution of ion can be theoretically or experimentally calculated,etc.In this study,firstly the surface characteristics of SiC monocrystal substrates before and after Pd ion implantation were examined by RBS/C,Raman,AFM and XPS,and then the process of Pd ion implantation was simulated by the Monte Carlo simulation software?SRIM-2008?.Moreover,the wettability of molten Al,Si,Cu,Al-Si and Al-Si-X?X=Cu,Zn,Mg?alloys on the SiC monocrystals before and after Pd ion implantation and the corresponding interfacial behavior were investigated.The main results or conclusions are as follows:The Pd existed mainly as elementary substance on the SiC substrate surface after the Pd ion implantation.Furthermore,the Pd ion implantation can improve the surface roughness of SiC,produce a certain lattice damage and high concentration of vacancy defects on the substrate surface,resulting in the decrease of the crystallinity of SiC surface and the increase of solid-vapor surface energy.And the Pd ion implantation can also change the solid-liquid interfacial energy by altering the interfacial interactions of metal/SiC system.As a result,the high-temperature wettability of metal/SiC system can be affected.The Pd ion implantation can affect the contact angle of pure metals and A1 alloys on SiC substrate at different levels.For the non-or low reactive systems,such as the Si/SiC and Al-12Si/SiC systems,the Pd ion implantation can increase the surface roughness and solid-vapor surface energy of SiC substrate to a certain extent,resulting in the improvement of wettability.However,for the reactive systems the Pd ion implantation can deteriorate the wettability of Al/SiC system and have no obvious effect on the wettability of Cu/SiC system.In particular,for the Al-Si/SiC system the Pd ion implantation can improve the wettability of metal/SiC system when the Si concentration in A1 alloy is lower than the equilibrium content.By contrast,the Pd ion implantation has only a quite limited effect on the wettability of Al-12Si/SiC system when the Si concentration exceeds the critical value.In these cases,For the Al-Si-X/SiC system,the Pd ion implantation can vary the interfacial interactions of A1₁0Si-4Cu/SiC and Al-12Si-2Mg/SiC systems and enhance the chemical reactions,resulting in the improve of wettability;however,no obvious variation on the wettability of A1-1OSi-1Zn/SiC system can be observed.The surface polarity of SiC has obvious influence on the wettability of A1-Si/SiC system.For the pure Si/SiC systems,the contact angle of Si/Si-terminated SiC is lower than that of Si/C-terminated SiC system while the contact angle of Al?Cu?/Si-terminated SiC is higher than that of Al?Cu?/C-terminated SiC system.Moreover,although the A1-Si/C-terminated SiC systems have lower interfacial reactivity,their wettability can be better than those of Al-Si/Si-terminated SiC systems.The alloying element?Si?and the third element?Cu,Zn and Mg?have significant influences on the wettability of Al-Si/SiC system.When the Si concentration is lower than the equilibrium content,the equilibrium or final contact angle of Al-Si/SiC system are higher than that of pure A1 on SiC substrate.However,the interfacial reactions are completely inhibited when the Si concentration exceeds the equilibrium content,the contact angle of Al-Si/SiC system is slight lower than that of Al/SiC system.The minor addition of Cu or Mg?2-4 wt.%?can enhance the interfacial reactions between the Al-Si alloys and SiC,resulting in the improvement of wettability of A1-10Si and Al-12Si on the SiC,respectively.Although the 10wt.%Zn addition can significantly reduce the contact angle of molten Al-lOSi on the SiC,which origin is that the serious evaporation behavior of Zn leads to the decrease of observed contact angle.