(119aq) Chemical Vapor Deposition of Aluminum Oxide Thin Films Using Dimethylaluminum Isopropoxide as a Single Source Precursor

            Ceramic oxides such as Al₂O₃
and HfO₂ are useful in microelectronics and as high temperature
thermal barriers. Thin films of these materials are attractive alternatives to
SiO₂ due to their dielectric attributes. Characterization and
control of their properties are keys to development for use in CMOS devices.
Chemical vapor deposition (CVD) is a popular processing method due to high
deposition rates and good conformality. The CVD process is inherently sensitive
to the choice of precursor. This study examines the use of dimethylaluminum
isopropoxide (DMAI) and methylaluminum di-isopropoxide (MADI) as CVD precursors
to aluminum oxide films. DMAI and MADI are respectively the one and two
methyl-isopropoxide substituted derivatives of the popular precursor
trimethylaluminum (TMA), making them similar in structure to aluminum
tri-isopropoxide (AIP). TMA exhibits a high vapor pressure and is a liquid at
room temperature, but is dangerous to handle and requires an additional
oxidant. AIP is a single-source precursor but requires heating for melting and
adequate vaporization, which can lead to system incompatibilities. Deposited
films are characterized by X-ray photoelectron spectroscopy (XPS), Auger
Electron Spectroscopy (AES), Rutherford backscattering spectrometry (RBS), and
variable angle spectroscopic ellipsometry. Understanding the relationships
between precursor structures and film composition, microstructure, and
processing windows will help the development of application specific
precursors.