Improved nucleation of TiN atomic layer deposition films on SiLK low-k polymer dielectric using an Al2O3 atomic layer deposition adhesion layer

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.

Recent Developments of Atomic Layer Deposition Processes for Metallization

“…Metal‐organic precursors, such as tetrakis(dimethylamido) [Ti(NMe) 2 ) 4 , TDMAT], tetrakis(diethylamido) [Ti(NEt) 2 ) 4 , TDEAT], and tetrakis(diethylmethylamido) [Ti(NEtMe) 4 , TEMAT] titanium have been used for TiN deposition, and NH 3 has been exclusively used to activate the reaction 44–53. Deposition temperatures ranging from 150 °C to 350 °C have been reported, and the deposited thin films are characteristically amorphous, but with a high content of C, O, and H impurities.…”

“…Similar to the halide processes, the metal‐organic TiN process also involves reduction of Ti 4+ into Ti 3+ . The reduction reaction is believed to take place during the NH 3 pulse in combination with the release of N 2 gas, as shown in Reactions 3 and 4 50 …”

Hollow Inorganic Nanospheres and Nanotubes with Tunable Wall Thicknesses by Atomic Layer Deposition on Self‐Assembled Polymeric Templates

“…Subsequently, the polymeric nanoparticles are coated with a thin layer of Al 2 O 3 using ALD. [19,21] Recently, polymers have been coated by ALD-grown inorganic thin films, on substrates such as flat films, [38][39][40][41][42][43][44] particles, [45][46][47] fibers [48] and even bottles. [49] The critical issue in coating the nanoscale polymeric templates is whether or not sufficiently low-temperature processes can be selected to avoid destruction of the template.…”

Atomic layer deposition of ZnO on ultralow-density nanoporous silica aerogel monoliths

“…The purpose of such an Al 2 O 3 nucleation layer was to prepare a densely hydroxylated surface to minimize any nucleation delay of the subsequent ALD of ZnO. 8 Between each exposure, the reactor was evacuated below 0.24 torr and then purged with ultrahigh purity Ar for 200 s.…”