AVS 51st International Symposium
    Electronic Materials and Processing Tuesday Sessions
       Session EM-TuM

Paper EM-TuM5
Simultaneous Formation of p- and n-type Ohmic Contacts to 4H-SiC using Ni/Ti/Al Contact Materials

Tuesday, November 16, 2004, 9:40 am, Room 304B

Session: Contacts and Metallization
Presenter: S. Tsukimoto, Kyoto University, Japan
Authors: S. Tsukimoto, Kyoto University, Japan
T. Sakai, Kyoto University, Japan
M. Murakami, Kyoto University, Japan
Correspondent: Click to Email
Both p- and n-type ohmic contacts are required for the future SiC power devices. Conventionally, these ohmic contacts are prepared using different materials and fabrication processes, because the current transport mechanisms for p- and n-type conductions are completely different. We succeeded to form simultaneously both p- and n-type ohmic contacts for 4H-SiC wide gap semiconductors using Ni/Ti/Al contact materials. The Ni/Ti/Al ohmic contacts were prepared by depositing sequentially Ni(20 nm), Ti(50 nm), and Al(50 nm) layers onto the p- and n-type SiC substrates which were doped with Al at 4.5x10@super 18@cm@super -3@ and with N at 1.4x10@super 19@cm@super -3@, respectively, and subsequently annealing at temperatures ranging form 600 °C to 1000 °C in an ultra high vacuum. The Ni/Ti/Al contacts showed ohmic behavior for both the p- and n-type SiC substrates after annealing at 800 °C. The specific contact resistances of these contacts for p- and n-type SiC were measured to be about 2x10@super -3@ @ohm@-cm@super 2@ and 3x10@super -4@ @ohm@-cm@super 2@, respectively. Based on interfacial microstructure analyzed by XRD measurements and cross-sectional TEM/HRTEM observations, the formation mechanism of the p/n-type Ni/Ti/Al ohmic contacts will be discussed.