AVS 50th International Symposium
    Electronic Materials and Devices Thursday Sessions
       Session EM-ThM

Paper EM-ThM11
ZrB@sub 2@ Diffusion Barriers: Conformal CVD Below 400 °C

Thursday, November 6, 2003, 11:40 am, Room 321/322

Session: Materials for Interconnects and Contacts to Semiconductors
Presenter: E.J. Klein, University of Illinois at Urbana-Champaign
Authors: E.J. Klein, University of Illinois at Urbana-Champaign
D.-Y. Kim, University of Illinois at Urbana-Champaign
S. Jayaraman, University of Illinois at Urbana-Champaign
G.S. Girolami, University of Illinois at Urbana-Champaign
J.R. Abelson, University of Illinois at Urbana-Champaign
Correspondent: Click to Email
Transition metal diborides are classified as "metallic ceramics" due to their high mechanical hardness, chemical stability, melting temperature > 3000 °C and low electrical resistivity. This combination of properties makes them attractive as diffusion barrier materials for the contact metallization in next-generation microelectronics or to wide bandgap semiconductors. We report the low temperature and fully conformal chemical vapor deposition of ZrB@sub 2@ thin films with essentially bulk properties. The ZrB@sub 2@ films are deposited at substrate temperatures of 200-500 °C using the single-source precursor Zr(BH@sub 4@)@sub 4@ and a concurrent flux of atomic hydrogen produced by a remote hydrogen plasma source. The films have a B/Zr atomic ratio of 2 and electrical resistivity < 40 µm@ohm@-cm; those produced at < 400 °C appear amorphous in X-ray diffraction. By contrast, films grown without the use of atomic hydrogen are B-rich, oxidize rapidly in air, and have high resistivity; these problems were typical of previous attempts to deposit ZrB@sub 2@ films reported in the literature. In this work, we study the diffusion barrier characteristics of ZrB@sub 2@ by annealing a sandwich structure of evaporated Cu (50 nm) / amorphous ZrB@sub 2@ (20 nm) / c-Si(100) [both n- and p-type]. For various annealing temperatures, we report the contact resistivity, stress, and micromorphology. Initial results show that no Cu diffuses into Si during annealing up to 650 °C for 30 minutes; the onset of Cu in-diffusion correlates with the appearance of crystalline X-ray diffraction peaks for ZrB@sub 2@. We will discuss the failure mechanism of the barrier material.