Paper AS-WeA9
Understanding the Relationship between Chemical Vapor Deposition Precursor Structure and Film Properties by Application of Electron, Optical, Ion, and X-ray Characterization Methods

Wednesday, October 22, 2008, 4:20 pm, Room 207

Ceramic oxides such as Al₂O₃ and HfO₂ are desirable in microelectronics as high-κ replacements of SiO₂ and in high temperature applications as protectants. For multi-component systems like CMOS devices and thermal barrier coatings, characterization and control of bulk and interfacial properties are important for optimal performance. Chemical vapor deposition (CVD) is popular for its high deposition rates and good conformality. However, final properties of a CVD film can be greatly influenced by the choice of precursor. Novel precursor ligand designs are used to increase volatility and precursor throughput, but can also affect film composition, microstructure, and the deposition window. In this study, ligand effects are investigated by understanding the deposition processes of dimethylaluminum isopropoxide (DMAI) and methylaluminum di-isopropoxide (MADI). These are derivatives of popular precursors trimethylaluminum (TMA) and aluminum tri-isopropoxide (AIP). TMA is well-suited for CVD bubbler delivery systems due to its high vapor pressure and liquid state at room temperature, but is dangerous to handle and requires an oxidant source. AIP has the advantage of being a single-source precursor for Al₂O₃, but requires melting at 130°C to achieve consistent precursor flux. DMAI and MADI represent one and two methyl-isopropoxide substitutions of TMA, respectively. A goal is to achieve a single precursor with beneficial characteristics of TMA and AIP. Film characterization by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), spectroscopic ellipsometry, and medium energy backscattering spectrometry provide insight into initial stage and bulk deposition. Correlation of composition, microstructure, and chemical state progression to deposition conditions will aid in the development of application-specific precursors.