Aluminum tri-isopropoxide as an alternative precursor for atomic layer deposition of aluminum oxide thin films

Abstract

Due to the safety challenges associated with the use of trimethylaluminum as a metal precursor for the deposition of alumina, different chemicals have been investigated over the years to replace it. The authors have investigated the use of aluminum tri-isopropoxide (TIPA) as an alternative alkoxide precursor for the safe and cost-effective deposition of alumina. In this work, TIPA is used as a stable Al source for atomic layer deposition (ALD) of Al 2 O 3 when different oxidizing agents including water, oxygen plasma, water plasma, and ozone are employed. The authors have explored the deposition of Al 2 O 3 using TIPA in ALD systems operating in vacuum and atmospheric pressure conditions. For thermal and plasma processes in vacuum ALD, a growth rate of 1.1-2 Å/ cycle achieved over a range of 140-300 °C is shown. Film density, roughness, and composition have been tested using various characterization techniques confirming comparable film properties to the thermal ALD of trimethylaluminum and water. The thermal water process at atmospheric pressure ALD (AP-ALD) resulted in a growth rate of up to 1.1 Å/cycle with residual carbon below the XPS detection limit. AP-ALD on nanoparticles shows different growth modes on TiO 2 versus SiO 2 nanoparticle surfaces confirmed by transmission electron microscopy analysis. Using TIPA as an ALD precursor would open up the possibility for a safer and cost-effective process for deposition of Al 2 O 3 in various applications.

Structural, Optical, and Electrical Properties of InOx Thin Films Deposited by Plasma-Enhanced Atomic Layer Deposition for Flexible Device Applications

“…When the growth temperature increased from 100 to 250 °C, the GPC increased slightly from 0.74 to 0.94 Å/cycle. Because this increment of GPC could be due to the decomposition of the precursor, a decomposition test , was conducted in an experiment in which only the DADI precursor without a co-reactant was injected; however, film growth from decomposition did not occur up to 250 °C. This result of an ALD window up to 250 °C is also in agreement with previous studies of thermal ALD InO x using a DADI precursor. , …”

Comparative In Situ Study of the Initial Growth Trends of Atomic Layer-Deposited Al2O3 Films

“…To date, Al 2 O 3 is one of the most extensively researched thin films deposited by ALD, owing to its high permittivity, chemical and thermal stability, good adhesion, and chemical compatibility with semiconductor processes. − This has led to Al 2 O 3 thin films being utilized in various applications, such as barrier materials, optical coatings, high-κ dielectric for gate oxides, and more. − ALD of Al 2 O 3 can be performed using AlCl 3 and H 2 O as precursors, but trimethylaluminum (TMA) is the best-known example, owing to its high reactivity, self-terminating reactions, and high-quality films even at low deposition temperatures. , Cost minimization and pyrophoric nature of TMA have led researchers to investigate substitute Al 2 O 3 precursors, including AlMe 2 Cl, − Al­(NEt 2 ) 3 , − Al­(NMe 2 ) 3 , Al­(OEt 3 ), Al­(O n Pr) 3 , , AlMe 2 O i Pr, − and many more. ,− …”

Group 11–14 Triazenides : Synthesis, characterization, and thermal evaluation for use in chemical vapor deposition

“…However, metal alkoxides have been used, for example, to deposit oxides of Li (lithium lanthanum titanate), Al, Si and Ti by ALD. [53][54][55][56]…”