AVS 50th International Symposium
    Thin Films Monday Sessions
       Session TF-MoA

Paper TF-MoA9
Expanding Thermal Plasma for Low-k Dielectrics: Guiding the Film Chemistry by Means of Selected Dissociation Paths in the Plasma

Monday, November 3, 2003, 4:40 pm, Room 329

Session: Atomic Layer Deposition and Low-k
Presenter: M. Creatore, Eindhoven University of Technology, The Netherlands
Authors: M. Creatore, Eindhoven University of Technology, The Netherlands
Y. Barrell, Eindhoven University of Technology, The Netherlands
W.M.M. Kessels, Eindhoven University of Technology, The Netherlands
M.C.M. van de Sanden, Eindhoven University of Technology, The Netherlands
Correspondent: Click to Email
As the need for low-k dielectrics in the ULSI technology becomes urgent, the research primarily focuses on the deposition of novel materials with appropriate electrical properties and on the challenges concerning their integration with subsequent processing steps. Within this framework, plasma-enhanced chemical vapour deposition of organosilicate glass films is considered promising due their chemical structure similar to SiO@sub 2@, which leads to a simpler process integration. In this contribution we address the remote expanding thermal plasma (ETP) as a novel technique for the deposition of low-k carbon-doped SiO@sub 2@ films from Ar/hexamethyldisiloxane (HMDSO)/oxygen mixtures. We have obtained low-k films which exhibit k values (yet not optimised) in the range 2.9-3.4 (at 1 MHz) and still fairly good mechanical properties (hardness of 1 GPa, modulus of 10 GPa). These results were not expected because literature, in general, reports on low-k films deposited from precursors with 2 Si-O and 1 Si-C bonds per Si atom (e.g., dimethoxymethylsilane and diethoxymethylsilane), in order to reach a compromise between dielectric and mechanical film properties. Our approach, on the contrary, utilizes HMDSO (apparently not suitable due to the high Si-CH@sub 3@: Si-O bond ratio) because the ETP technique allows selecting different fragmentation paths for the precursor and this can eventually be turned to the progressive cleavage of Si-C bonds. The relatively easy control on the process kinetics can be monitored by means of gas phase diagnostics, such as Mass Spectrometry and Cavity Ring Down Spectroscopy. The information on the HMDSO dissociation paths allows tailoring the organic functionalities in the low-k films by means of IR absorption spectroscopy, XPS, and spectroscopic ellipsometry.