No abstract

This study demonstrates that atomic layer chemical vapor deposition is an excellent technique for growing epitaxial TiO 2 thin films at low temperatures. Using TiI 4 and H 2 O 2 as precursors, both the rutile and anatase phases could be deposited. Anatase is invariably obtained at lower deposition temperatures, but the temperature of the anatase/rutile phase boundary is affected by the substrate material chosen. Phase-pure rutile was obtained down to 275ЊC on a-Al 2 O 3 (0 1 2), while phase-pure anatase was obtained up to 375ЊC on MgO (0 0 1). The rutile phase was found to grow epitaxially on both ␣-Al 2 O 3 (0 1 2) and ␣-Al 2 O 3 (0 0 1) substrates with the in-plane orientational relationships, and [0 1 0] rutile //[1 0 0] ␣-Al 2 O3 , respectively. The anatase phase was found to grow epitaxially on MgO (0 0 1) with the in-plane orientational relationships [0 1 0] anatase //[0 1 0] MgO and [0 0 1] anatase //[1 0 0] MgO . The scan X-ray diffraction measurements verified that epitaxy was still obtained at a deposition temperature of 375ЊC. This deposition temperature is considerable lower than those commonly applied to realize heteroepitaxy of titanium oxide films.

No abstract

Diffusion barriers are required to prevent copper from diffusing into low-k polymer dielectrics in backend interconnects. The ability to deposit conformal diffusion barriers onto high aspect ratio, low-k polymer features requires atomic layer deposition ͑ALD͒ techniques. This study examined TiN ALD on SiLK ͑a trademark of the Dow Chemical Company͒ low-k polymer dielectric using tetrakis-dimethylamino titanium and NH 3 . X-ray fluorescence spectroscopy ͑XRFS͒, optical microscopy, and surface profiling of the TiN ALD films deposited on SiLK revealed discontinuous films displaying distinct patchy regions. The patches corresponded to a thinner TiN coating and were attributed to difficulties for TiN ALD nucleation on SiLK. To study TiN ALD nucleation, in situ quartz-crystal microbalance ͑QCM͒ measurements were performed by spincoating SiLK onto the QCM sensor. Subsequent QCM measurements during TiN ALD revealed very low initial TiN ALD growth rates indicating poor nucleation. Al 2 O 3 ALD was then performed on the SiLK film using trimethyl aluminum and H 2 O. Surface profiling, XRFS, QCM, and transmission electron microscopy measurements revealed that the Al 2 O 3 ALD film nucleates immediately on SiLK producing a continuous Al 2 O 3 film. In addition, QCM measurements showed that TiN ALD nucleates readily on the Al 2 O 3 surface. The Al 2 O 3 ALD adhesion layer facilitated the growth of a continuous TiN ALD film on SiLK. Examination of TiN ALD films prepared on SiLK with progressively thinner Al 2 O 3 ALD adhesion layers revealed that 10 Al 2 O 3 ALD cycles were sufficient to promote the nucleation of the TiN ALD film.