AVS 49th International Symposium
    Plasma Science Thursday Sessions
       Session PS+TF-ThM

Paper PS+TF-ThM4
Expanding Thermal Plasma for SiO@sub 2@ Films: A Chemistry-controlled Process and an Insight into the Deposition Mechanism

Thursday, November 7, 2002, 9:20 am, Room C-103

Session: Plasma Enhanced Deposition
Presenter: M. Creatore, Eindhoven University of Technology, The Netherlands
Authors: M. Creatore, Eindhoven University of Technology, The Netherlands
M. Kilic, Eindhoven University of Technology, The Netherlands
K. O'Brien, Eindhoven University of Technology, The Netherlands
M.C.M. Van de Sanden, Eindhoven University of Technology, The Netherlands
Correspondent: Click to Email
SiO@sub 2@ PECVD by means of organosilicon/O@sub 2@ mixtures has shown its versatility in many fields, as e.g. IC/MEMS, photonics, optics, mechanics, food packaging. However, some issues concerning the deposition process remain unresolved. For example, the deposition precursors have not been unambiguously identified, hampering a direct correlation between plasma species densities and film composition. The remote expanding thermal plasma (ETP) is introduced as a simplified approach to get insight into the hexamethyldisiloxane (HMDSO)/O@sub 2@ deposition process. HMDSO is injected downstream in the expanding argon plasma (generated in a dc cascaded arc) by means of a ring. Because of the expansion, the electron temperature drops to about 0.3 eV: electron-induced dissociations are negligible and the chemical activity is controlled by the (Ar@super +@, e@super -@) flow from the arc. The ETP has led to a step-by-step entirely chemistry-controlled process (no ion bombardment) from silicone-like to C-free and dense SiO@sub 2@ films, at competitive growth rates (8 nm/s). A multidiagnostics approach has been applied to study the fragmentation and reactions of HMDSO. Cavity Ring Down Spectroscopy (CRD) has been used for OH, CH and CH@sub 3@ radicals detection in HMDSO/O@sub 2@ plasmas. Together with Mass Spectrometry, CRD has shown that the Si-C bond in the HMDSO molecule appears to break only at very high Ar@super +@ flux (high arc Ar flow rate and current). Milder conditions favour the Si-O and C-H bond scissions. Films are characterized by means of IR absorption spectroscopy, in situ single wavelength ellipsometry and ex situ spectroscopic ellipsometry. In the presentation the relation between the film properties and the plasma characterization will be addressed.