Atomic Layer Deposition of TiO2 on Si and GaAs Substrates Using TDMATi and H2O Precursors
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Date
2009-01-01
Type of Work
Department
Physics
Program
Physics, Applied
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Access limited to the UMBC community. Item may possibly be obtained via Interlibrary Loan through a local library, pending author/copyright holder's permission.
Abstract
Atomic layer deposition involving TDMATi and H<sub>2 sors is used to grow TiO<sub>2 lms in a homemade hot-wall, flowtube reactor. Process optimization and film properties are studied for films grown on Si substrates. Spectroscopic ellipsometry indicates an optimal growth rate at a substrate temperature of 200C. RBS shows a consistent coverage of Ti atoms over a large cycle range. X-ray spectroscopy reveals that the films contain very little bulk contamination and are slightly over-oxidized. FTIR and X-ray diffraction spectra show that as-deposited films are amorphous and form into the rutile crystal structure when they are annealed at 900C. Surface roughness is measured with AFM and is shown to be 3-4% of the film's thickness. Films are grown on GaAs substrates and ex-situ X-ray spectroscopy is used to determine interface properties. Gradual consumption of the native oxides is observed during deposition. After 250 ALD cycles, 26 of native oxide is reduced to less than a monolayer with trace amounts of AsO<sub>x sub>2 ing. The consumption of the oxide is attributed to the presence of dimethylamino ligands in the TDMATi precursor. For GaAs substrates whose native oxides are etched prior to deposition, the oxides are not regrown during deposition.