Self-reducing Precursors for Aluminium Metal Thin Films: Evaluation of Stable Aluminium Hydrides for Vapor Phase Aluminium Deposition

13 March 2024, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Thin films of Al as interconnect materials and those of AlN as wide bandgap semiconductor and piezoelectric material are of great interest for microelectronic applications. For the fabrication of these thin films via chemical vapor deposition (CVD) based routes, the available precursor library is rather limited, mostly comprising aluminium alkyls, chlorides, and few small amine-stabilized aluminium hydrides. Herein, we focused on rational precursor development for Al, their characterization and comparison to existing precursors comprising stabilized aluminium hydrides. We present and compare a series of potentially new and reported aluminium hydride precursors divided into three main groups with respect to their stabilization motive, and their systematic structural variation to evaluate the physicochemical properties. All compounds were comprehensively characterized by means of nuclear magnetic resonance spectroscopy (NMR), Fourier-transform infrared spectroscopy (FTIR), elemental analysis (EA), electron impact-mass spectrometry (EI-MS) and thermogravimetric analysis (TGA). Promising representatives were further evaluated as potential single source precursors for aluminium metal formation in proof-of-concept experiments. Structure and reaction enthalpies with NH3 or H2 as co-reactants were calculated via first principles density functional theory simulations and show the great potential as atomic layer deposition (ALD) precursors for Al and AlN thin films.



Supplementary materials

Supporting Information for Stabilized Aluminum Hydride Complexes as Potential Precursors for Vapor Phase Deposition Processes
Figure_SI 1 Solid state structure with the displacement ellipsoid plot (50 % probability) of [Al(DMP)H2] (1). Table_SI 1 Crystallographic data and structure refinement for [Al(DMP)H2] (1). Table_SI 2 Selected bond distances and bond angles for [Al(CMP)H2] (1). Hydrogen H1* is corresponding to dimer molecule. Table_SI 3 Summarized onsets of volatilization (Tvol.) determined by 1 % mass loss taken from TGA for compound 1 – 9. Figure_SI 2 Compound 2 after one week of storage at room temperature under inert conditions. The formation of a foam like, brittle solid was observed.


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