AVS 47th International Symposium
    Electronics Tuesday Sessions
       Session EL-TuP

Paper EL-TuP2
Low Temperature, Single-Source CVD of ZrB2 and HfB2 Films as Cu Diffusion Barriers and Interconnects in Next-Generation ULSI

Tuesday, October 3, 2000, 5:30 pm, Room Exhibit Hall C & D

Session: Poster Session
Presenter: J.H. Sung, University of Illinois at Urbana-Champaign
Authors: J.H. Sung, University of Illinois at Urbana-Champaign
D.M. Goedde, 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
Thin films of the metallic ceramics ZrB@sub 2@ and HfB@sub 2@ have high electrical conductivity and are very effective diffusion barriers against copper; hence, they are attractive as interconnect and barrier materials for next-generation ULSI technology. Previously, we deposited highly conformal (~ 100 % bottom coverage) ZrB@sub 2@ and HfB@sub 2@ films using Zr(BH@sub 4@)@sub 4@ and Hf(BH@sub 4@)@sub 4@ single-source precursors in a CVD reactor with a remote hydrogen plasma source. The atomic H enhanced the release of excess B from the growth surface at low temperature, producing stoichiometric films with excellent properties. The film structure could be controllably varied from amorphous to polycrystalline by varying the substrate temperature from 250 - 800 °C, while maintaining stoichimetry. Here, we demonstrate that a single layer of ZrB@sub 2@ or HfB@sub 2@ can successfully replace the complex W/TiN/TiSi@sub 2@ multilayer that is currently used for ULSI metallization of Si. To achieve low contact resistivity on p-type Si, we adjust the ZrB@sub 2@ or HfB@sub 2@ stoichiometry during the initial deposition in order to provide a controlled source of excess B atoms. This is done by briefly reducing the remote hydrogen plasma power, which increases the B content above stoichiometric ratio. We will also present results for ZrB@sub 2@ or HfB@sub 2@ deposited at < 300 °C: electrical resistivity less than 40 µm@ohm@-cm, effective diffusion barrier against Cu during annealing to 700 °C for 1 hour, and low specific contact resistivity.