Overview of materials and bonding techniques for inner connections in SiC high power and high temperature applications

There are two main technical problems which should be overcome for practical applications of SiC power devices. One of them is the formation of reproducible ohmic contacts and second one is creation connection system between SiC ohmic contacts and package leads. The paper presents a compatibility of materials system for metallization of ohmic contacts to n-SiC and metallization of DBC substrate pads which both are well-suited and able to create stable connection system using wire bonding or flip chip bonding techniques. Such materials systems should work at temperatures up to 350°C or higher. Al and Au were applied as materials for wire bonding or flip chip bonding. Our experiments allow to conclude that for high temperature applications the Al wire bonding to SiC/Ti ohmic contacts with Al top metallization and DBC substrate with Ni metallization should be good in devices working up to 350°C. Moreover, Au wire bonding to the SiC/Ti ohmic contact with Au or Pt top metallization and the DBC substrate covered Ni/Au can be applied in devices working up to 400°C. For Au balls flip chip bonding a good solution is the SiC/Ti ohmic contact with Au or Pt top metallization and the DBC substrate with Ni/Au metallization. Such system can work up to 350°C.