AVS 52nd International Symposium
    Electronic Materials and Processing Tuesday Sessions
       Session EM-TuP

Paper EM-TuP4
Nucleation Behavior of Ru Thin Films Prepared by MOCVD on TiN Substrate with TiCl@sub 4@ Pre-Treatment

Tuesday, November 1, 2005, 4:00 pm, Room Exhibit Hall C&D

Session: Electronic Materials and Processing Poster Session
Presenter: B.S. Kim, Seoul National University, Korea
Authors: B.S. Kim, Seoul National University, Korea
H.S. Seo, Seoul National University, Korea
C.S. Hwang, Seoul National University, Korea
S.Y. Kang, Samsung Electronics Co., Ltd., Korea
J.Y. Kim, Samsung Electronics Co., Ltd., Korea
K.H. Lee, Samsung Electronics Co., Ltd., Korea
H.J. Lim, Samsung Electronics Co., Ltd., Korea
C.Y. Yoo, Samsung Electronics Co., Ltd., Korea
S.T. Kim, Samsung Electronics Co., Ltd., Korea
H.J. Kim, Seoul National University, Korea
Correspondent: Click to Email
Due to the excellent characteristics, such as low electrical resistivity and good dry etching property, ruthenium (Ru) is considered as a candidate material for capacitor electrodes in gigabit scale dynamic random access memories (DRAMs). In a typical concave type storage node of gigabit scale DRAMs, the Ru bottom electrodes should be deposited on the TiN diffusion barrier. But the metalorganic chemical vapor deposition (MOCVD) of Ru on the TiN surface has been suffered from the poor nucleation behavior and rough surface morphologies, which makes the capacitor fabrication difficult. In this study, the Ru films were deposited by MOCVD using Ruthenium-(2,4-Demethylpentadienyl)(Ethylcyclopentadienyl)[Ru(DER)] on various substrates, such as Ta@sub 2@O@sub 5@, TiN, SiO@sub 2@ and TiO@sub 2@. The nucleation rate of Ru on the TiN surface was improved by the TiCl@sub 4@ pre-treatment which was done by atomic layer deposition (ALD). The Ru thin films deposited on Ta@sub 2@O@sub 5@ and TiO@sub 2@ with oxygen addition at 300°C have continuous and smooth surfaces while those on SiO@sub 2@ and TiN have discontinuous film morphologies. It is suggested that the different surface morphologies of Ru films were mainly attributed to the difference of bonding type of the substrates. The surfaces with highly ionic bonding characteristics, such as Ta@sub 2@O@sub 5@ and TiO@sub 2@, can share the surface electron cloud with the metallic Ru dimer resulting in lowering of nucleation barrier energy. Therefore surface modification of TiN surface that has highly covalent bonding characteristics can improve the nucleation rate of Ru. The pre-treatment with ALD-TiCl@sub 4@ enhanced the nucleation rate of Ru films mainly due to the partial oxidation of TiCl@sub 4@ that results in the formation of seed-like TiO@sub 2@ layer. The conformal deposition of Ru on the contact-hole structure and on the bottom TiN surfaces was successfully obtained via surface modification using TiCl@sub 4@.