AVS 53rd International Symposium
    Electronic Materials and Processing Tuesday Sessions
       Session EM-TuA

Paper EM-TuA5
Diffusion Barriers for High-Temperature Reliability of SiC Junction Field Effect Transistors

Tuesday, November 14, 2006, 3:20 pm, Room 2003

Session: Materials for Power Electronics
Presenter: S.E. Mohney, The Pennsylvania State University
Authors: S.E. Mohney, The Pennsylvania State University
C.M. Eichfeld, The Pennsylvania State University
B.Z. Liu, The Pennsylvania State University
A.V. Adedeji, Auburn University
J.R. Williams, Auburn University
S.H. Wang, The Pennsylvania State University
A. Owen, The Pennsylvania State University
S.-H. Ryu, Cree
S. Krishnaswami, Cree
Correspondent: Click to Email
Tantalum-bearing diffusion barriers show considerable promise for the protection of contacts to SiC in air at high temperatures. Such barriers include Ta-Si-N, Ta-Si, Ta-Ru-N, and Ta-Ru. In this presentation, we report the high-temperature reliability of metallization stacks aged in air at 350°C for 5,000 h or longer. For many of the diffusion barrier compositions, the ohmic contacts beneath them maintain low specific contact resistances in the mid-10@super -5@ Ohm cm@super 2@ range as well as strong adhesion between the layers. We have also used Auger electron depth profiling to help us understand why some metallization stacks survive and others fail. Contrary to our original expectations, the addition of N can be detrimental to the Ta-Ru barriers because N is lost to the environment during aging, hastening oxidation. The most promising barriers have been successfully integrated into SiC JFETs, and the devices are now being aged at 350°C in TO-258 open cavity packages and periodically tested.