Properties of Aluminum Oxide and Aluminum Oxide Alloys and their Interfaces with Silicon and Silicon Dioxide.

Abstract

A remote plasma enhanced chemical vapor deposition method, RPECVD, was utilized to deposit thin films of aluminum oxide, tantalum oxide, tantalum aluminates, and hafnium aluminates. These films were analyzed using auger electron spectroscopy, AES, Fourier transform infrared spectroscopy, FTIR, X-ray diffraction, XRD, nuclear resonance profiling, NRP, capacitance versus voltage, C-V, and current versus voltage, J-V. FTIR indicated the alloys were homogeneous and pseudobinary in character. Combined with XRD the crystallization temperatures for films >100 nm were measured. The alloys displayed an increased temperature stability with the crystallization points being raise by >100°C above the end point values.In-situ AES analysis provided a study of the initial formation of the films' interface with the silicon substrate. For Al2O3 these results were correlated to NRP results and indicated a thin, ~0.6 nm, interfacial layer formed during deposition.C-V characteristics indicated a layer of fixed negative charge associated with Al2O3. For Ta2O5 the C-V and J-V results displayed high levels of leakage current, due to a low conduction band offset with silicon. Both aluminates were dominated by electron trapping states. These states were determined to be due to (i) a network 'break-up' component and (ii) localized atomic d-states of hafnium and tantalum atoms.