AVS 45th International Symposium
    Applied Surface Science Division Monday Sessions
       Session AS-MoP

Paper AS-MoP4
Study on Reaction Mechanism of Aluminum Chemical Vapor Deposition with In-situ XPS and TOF-SIMS Measurements

Monday, November 2, 1998, 5:30 pm, Room Hall A

Session: Aspects of Applied Surface Science Poster Session
Presenter: K. Tanaka, Sumitomo Chemical Co., Ltd., Japan
Authors: K. Tanaka, Sumitomo Chemical Co., Ltd., Japan
H. Yanashima, Sumitomo Chemical Co., Ltd., Japan
T. Yako, Sumika Chemical Analysis Service Ltd., Japan
K. Kamio, Sumitomo Chemical Co., Ltd., Japan
K. Sugai, NEC Corporation, Japan
S. Kishida, NEC Corporation, Japan
Correspondent: Click to Email
Chemical vapor deposition (CVD) of Al is one of the most promising methods for multilevel metallization of ultra-large-scale integration (ULSI) circuits as it can fill via holes that have sub-half-micron diameters and high aspect ratios with superior step coverage. However, the surface morphology of CVD Al films deposited on oxidized Si surfaces is generally unsatisfactory. The CVD Al films deposited on TiN barrier layers, on the other hand, show much smoother surfaces due to higher Al island density in the early stage of growth.@footnote 1@ In the present work, the reactions of dimethylaluminum hydride (DMAH; (CH@sub 3@)@sub 2@AlH) with slightly oxidized TiN and Si surfaces were investigated in situ with x-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Si substrates with/without TiN surface layer were introduced into a UHV chamber. After evacuation H@sub 2@ gas was introduced at a pressure of 1x10@super -3@ Pa and the substrates were heated to 200°C, following the introduction of DMAH vapor at partial pressures of 1x10@super -6@ to 1x10@super -4@ Pa. After CVD reaction, the chamber was evacuated to UHV again and the specimens were transfered to XPS and TOF-SIMS spectrometers in vacuum. It was observed that the native oxide layer formed on TiN surface was reduced when exposed to DMAH vapor and a clean TiN surface became to appear. The reduction of oxide and deposition of Al on TiN surface were enhanced with increase of DMAH exposure. In contrast with the TiN surface, no reduction of native oxide layer by DMAH was observed on Si surface except the uppermost surface analyzed by TOF-SIMS. The amount of Al deposited on Si surface was also decreased and substantially equal independent of DMAH exposure. The reduction of oxide and appearance of clean TiN surface must be important to account for the nucleation mechanisms of Al film growth on TiN during CVD. The difference of chemical states of adsorbed DMAH molecules on TiN and Si surfaces will also be discussed. @FootnoteText@ @footnote 1@K. Sugai, H. Okabayashi, T. Shinzawa, S. Kishida, T. Kobayashi, N. Hosokawa, T. Yako, H. Kadokura, M. Isemura, and K. Kamio, Proceedings of the 10th International IEEE VLSI Multilevel Interconnection Conference, 1993 (IEEE, New York, 1993), p. 463.