IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Plasma Science Tuesday Sessions
       Session PS-TuP

Paper PS-TuP30
Amorphous Metal-organic Chemical Vapor Deposition Nb@sub x@Ta@sub (1-x)@N Films for Diffusion Barrier

Tuesday, October 30, 2001, 5:30 pm, Room 134/135

Session: Plasma Deposition, Modeling, and Emerging Applications Poster Session
Presenter: W.C. Gau, National Tsing Hua University, Taiwan, R.O.C.
Authors: W.C. Gau, National Tsing Hua University, Taiwan, R.O.C.
C.W. Wu, National Tsing Hua University, Taiwan, R.O.C.
T.C. Chang, National Sun Yat-Sen University, Taiwan, R.O.C.
C.H. Li, National Chiao Tung University, Taiwan, R.O.C.
C.J. Chu, Nanmat Technology Co., LTD., Taiwan, R.O.C.
C.H. Chen, Nanmat Technology Co., LTD., Taiwan, R.O.C.
L.J. Chen, National Tsing Hua University, Taiwan, R.O.C.
Correspondent: Click to Email
To incorporate Cu into interconnection structures, it is necessary to introduce diffusion barrier to prevent Cu from entering the silicon substrate and to form deep level traps. The presence of grain boundaries in the film is generally detrimental to the diffusion barrier properties. One way to eliminate grain boundaries is to render the barrier structure amorphous. In the present work, the resistivity, composition, crystal structure, and microstructure of Nb@sub x@Ta(@sub (1-x)@N film were investigated. Amorphous diffusion barrier of Nb@sub x@Ta@sub (1-x)@N films were deposited in a CVD system with mixed precursors ( 75% NB= (Net@sub 2@)@sub 4@ and 25% (Net@sub 2@)@sub 3@Ta=NEt ) and NH@sub 3@ gas. The Nb@sub x@Ta@sub (1-x)@N films were deposited at substrate temperatures of 375-500 °C, reactor working pressures of 0.3-0.5 Torr, Argon carrier flow rate of 10 sccm, ammonia reactant flow rates between 5 and 30 sccm. The thermal stability was evaluated by electrical measurement. In addition, the barrier films were deposited onto patterned wafer with 0.2 µm-contact holes to check the step coverage. The effects of N@sub 2@/H@sub 2@/NH@sub 3@ gaseous plasma (200W) post-treatment with various times (3-10 min) were also investigated. The films were subsequently characterized by transmission electron microscopy (TEM). Depth profile and the chemical environment of elements in the films were analyzed by x-ray photoelectron spectroscopy (XPS). The amorphous Nb@sub x@Ta@sub (1-x)@N films were found to contain a low C concentration (10%), high N concentration (40%), and low resistivity with NH@sub 3@ as a reactant gas. The resistivity of barrier was increased with time owing to the absorption of oxygen in the atmosphere. NH@sub 3@ plasma post-treatment for 3 min was found to be effective in preventing the oxidation and reducing the resistivity. The Nb@sub x@Ta@sub (1-x)@N films were found to be an effective barrier up to 550 °C for 30 min.