AVS 45th International Symposium
    Electronic Materials and Processing Division Tuesday Sessions
       Session EM+SE-TuM

Paper EM+SE-TuM10
Thermochemical Stability of Plasma-Deposited Silicon Oxycarbide Thin Films Subjected to Post-Deposition Rapid Thermal Annealing

Tuesday, November 3, 1998, 11:20 am, Room 316

Session: Critical Issues in Widebandgap Semiconductors
Presenter: D.M. Wolfe, North Carolina State University
Authors: D.M. Wolfe, North Carolina State University
B. Ward, North Carolina State University
F. Wang, North Carolina State University
M. Xu, North Carolina State University
G. Lucovsky, North Carolina State University
R.J. Nemanich, North Carolina State University
D.M. Maher, North Carolina State University
Correspondent: Click to Email
Low defect density gate dielectrics are of critical importance to maximize electrical performance/reliability in SiC high power devices. Under some growth conditions carbon atoms are trapped in thermally-grown oxides forming silicon oxycarbides@footnote 1@, and it has been suggested that these C-atoms degrade device performance. The bonding of C-atoms in silicon oxycarbides as well as their thermal stability is therefore addressed. Thin silicon suboxide (SiO@sub x@, x<2) and silicon oxycarbide (SiO@sub x@C@sub y@, x<2, y<<1) films were deposited at 250°C by remote-plasma enhanced CVD. Changes in the local chemical bonding and the onset of crystallization upon rapid thermal annealing at temperatures from 600-1100°C were investigated. XPS and RBS were used for compositional analysis; FTIR was used to track the extent of structural/chemical changes through shifts in Si-O and Si-C bond-stretching frequencies. Raman spectroscopy, and HRTEM/selective area diffraction were used to monitor crystallization products through the appearance of characteristic phonon modes and diffraction patterns, respectively. These studies showed a structural/chemical transformation occurred at about 900°C for silicon suboxide films. At this temperature, the end-product material was comprised of Si nanocrystals imbedded in an non-crystalline SiO@sub 2@ matrix. A similar structural/chemical transformation, in which Si nanocrystals were also formed, was observed between 1000 and 1050°C for the silicon oxycarbides. However, a siloxane-type Si-O-C bond was observed to form at intermediate temperatures (~900°C), and to disappear upon crystallization. No evidence for amorphous or crystalline C-C bonds, or other C-O bonding groups was found in the oxycarbide films before, or after annealing. Finally, concentrations of Si and O, and Si, O and C remained essentially the same for the respective as-deposited and fully-annealed films. @FootnoteText@ @footnote 1@ B. Hornetz, H-J. Michel, J. Halbritter, J. Mater. Res 9, 3088 (1994).