AVS 49th International Symposium
    Thin Films Wednesday Sessions
       Session TF+VT-WeM

Paper TF+VT-WeM5
Improved Nucleation of TiN ALD Films on Low k Polymer Dielectrics Using Al@sub 2@O@sub 3@ ALD Adhesion Layers

Wednesday, November 6, 2002, 9:40 am, Room C-101

Session: Atomic Layer Deposition - Barriers & Nitrides
Presenter: C.A. Wilson, University of Colorado
Authors: C.A. Wilson, University of Colorado
J.W. Elam, University of Colorado
M. Schuisky, University of Colorado
Z.A. Sechrist, University of Colorado
S.M. George, University of Colorado
Correspondent: Click to Email
Diffusion layers are required to prevent copper from diffusing into low k polymer dielectrics in backend interconnects. The ability to deposit conformal diffusion layers, such as TiN, onto high aspect ratio low k polymer features requires atomic layer deposition (ALD) techniques. This study examined TiN ALD on low k polymer dielectrics using tetrakis-dimethylamino titanium (TDMAT) and NH@sub 3@. X-ray fluorescence spectroscopy (XRFS), optical microscopy and surface profiling of the TiN ALD films deposited on the low k polymer dielectrics revealed discontinuous films displaying distinct patchy regions of thinner TiN coating. To study TiN ALD nucleation, in situ quartz crystal microbalance (QCM) measurements were performed by spin-coating a low k polymer dielectric onto the QCM sensor. Subsequent QCM measurements during TiN ALD revealed very low initial TiN ALD growth rates indicating poor nucleation. Al@sub 2@O@sub 3@ ALD was then performed on the low k polymer dielectric using trimethyl aluminum and H@sub 2@O. Surface profiling, XRFS, QCM and transmission electron microscopy measurements revealed that the Al@sub 2@O@sub 3@ ALD films nucleate immediately on the low k polymer dielectric producing continuous Al@sub 2@O@sub 3@ films. In addition, QCM measurements showed that TiN ALD nucleates readily on the Al@sub 2@O@sub 3@ surface. Intermediate Al@sub 2@O@sub 3@ ALD adhesion layers may facilitate the growth of continuous TiN ALD films on low k polymer dielectrics. Examination of TiN ALD films prepared on low k polymer dielectrics with progressively thinner Al@sub 2@O@sub 3@ ALD adhesion layers revealed that 10 Al@sub 2@O@sub 3@ ALD cycles are sufficient to promote the nucleation of the TiN ALD films.