Nucleation and Growth of Dielectric Films on III-V Semiconductors During Atomic Layer Deposition

Persistent Link:
http://hdl.handle.net/10150/265341
Title:
Nucleation and Growth of Dielectric Films on III-V Semiconductors During Atomic Layer Deposition
Author:
Granados-Alpizar, Bernal
Issue Date:
2012
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
In order to continue with metal-oxide-semiconductors (CMOS) transistor scaling and to reduce the power density, the channel should be replaced with a material having a higher electron mobility, such as a III-V semiconductor. However, the integration of III-V's is a challenge because these materials oxidize rapidly when exposed to air and the native oxide produced is characterized by a high density of defects. Deposition of high-k materials on III-V semiconductors using Atomic Layer Deposition (ALD) reduces the thickness of these oxides, improving the semiconductor/oxide interface quality and the transistor electrical characteristics. In this work, ALD is used to deposit two dielectrics, Al₂O₃ and TiO₂, on two III-V materials, GaAs and InGaAs, and in-situ X-ray photoelectron spectroscopy (XPS) and in-situ thermal programmed desorption (TPD) are used for interface characterization. Hydrofluoric acid (HF) etching of GaAs(100) and brief reoxidation in air produces a 9.0 ± 1.6 Å-thick oxide overlayer containing 86% As oxides. The oxides are removed by 1 s pulses of trimethylaluminum (TMA) or TiCl₄. TMA removes the oxide overlayer while depositing a 7.5 ± 1.6 Å thick aluminum oxide. The reaction follows a ligand exchange mechanism producing nonvolatile Al-O species that remain on the surface. TiCl₄ exposure removes the oxide overlayer in the temperature range 89°C to 300°C, depositing approximately 0.04 monolayer of titanium oxide for deposition temperatures from 89°C to 135°C, but no titanium oxide is present from 170°C to 230°C. TiCl₄ forms a volatile oxychloride product and removes O from the surface while leaving Cl atoms adsorbed to an elemental As layer, chemically passivating the surface. The native oxide of In(0.53)Ga(0.47)As(100) is removed using liquid HF and gas phase HF before deposition of Al₂O₃ using TMA and H₂O at 170°C. An aluminium oxide film with a thickness of 7.2 ± 1.2 Å and 7.3 ± 1.2 Å is deposited during the first pulse of TMA on liquid and gas phase HF treated samples, respectively. After three complete ALD cycles the thickness of the aluminum oxide film is 10.0 ± 1.2 Å on liquid HF treated and 6.6 ± 1.2 Å on gas phase HF treated surfaces. Samples treated with gas phase HF inhibit growth. Inhibition is caused by residual F atoms that passivate the surface and by surface poisoning due to the thicker carbon film deposited during the first pulse of TMA. On InGaAs covered by native oxide, the first TMA pulse deposits 9 Å of aluminum oxide, and reaches saturation at 13 Å after 15 pulses of TMA. The film grows by scavenging oxygen from the substrate oxides. Substrate oxides are reduced by the first pulse of TMA even at 0°C. At 0°C, on a 9 Å thick Ga-rich oxide surface, 1 pulse of TMA mainly physisorbs and a limited amount of aluminum oxide is deposited. At 0°C, 110°C, and 170°C, more aluminum oxide is deposited on surfaces initially containing As oxide, and larger binding energy (BE) shifts of the O 1s peak are observed compared to surfaces that contain Ga oxides only, showing that As oxides improve the nucleation of Al₂O₃.
Type:
text; Electronic Dissertation
Keywords:
GaAs; InGaAs; in situ; nucleation; Chemical Engineering; ALD; alumina
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Chemical Engineering
Degree Grantor:
University of Arizona
Advisor:
Muscat, Anthony J.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleNucleation and Growth of Dielectric Films on III-V Semiconductors During Atomic Layer Depositionen_US
dc.creatorGranados-Alpizar, Bernalen_US
dc.contributor.authorGranados-Alpizar, Bernalen_US
dc.date.issued2012-
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractIn order to continue with metal-oxide-semiconductors (CMOS) transistor scaling and to reduce the power density, the channel should be replaced with a material having a higher electron mobility, such as a III-V semiconductor. However, the integration of III-V's is a challenge because these materials oxidize rapidly when exposed to air and the native oxide produced is characterized by a high density of defects. Deposition of high-k materials on III-V semiconductors using Atomic Layer Deposition (ALD) reduces the thickness of these oxides, improving the semiconductor/oxide interface quality and the transistor electrical characteristics. In this work, ALD is used to deposit two dielectrics, Al₂O₃ and TiO₂, on two III-V materials, GaAs and InGaAs, and in-situ X-ray photoelectron spectroscopy (XPS) and in-situ thermal programmed desorption (TPD) are used for interface characterization. Hydrofluoric acid (HF) etching of GaAs(100) and brief reoxidation in air produces a 9.0 ± 1.6 Å-thick oxide overlayer containing 86% As oxides. The oxides are removed by 1 s pulses of trimethylaluminum (TMA) or TiCl₄. TMA removes the oxide overlayer while depositing a 7.5 ± 1.6 Å thick aluminum oxide. The reaction follows a ligand exchange mechanism producing nonvolatile Al-O species that remain on the surface. TiCl₄ exposure removes the oxide overlayer in the temperature range 89°C to 300°C, depositing approximately 0.04 monolayer of titanium oxide for deposition temperatures from 89°C to 135°C, but no titanium oxide is present from 170°C to 230°C. TiCl₄ forms a volatile oxychloride product and removes O from the surface while leaving Cl atoms adsorbed to an elemental As layer, chemically passivating the surface. The native oxide of In(0.53)Ga(0.47)As(100) is removed using liquid HF and gas phase HF before deposition of Al₂O₃ using TMA and H₂O at 170°C. An aluminium oxide film with a thickness of 7.2 ± 1.2 Å and 7.3 ± 1.2 Å is deposited during the first pulse of TMA on liquid and gas phase HF treated samples, respectively. After three complete ALD cycles the thickness of the aluminum oxide film is 10.0 ± 1.2 Å on liquid HF treated and 6.6 ± 1.2 Å on gas phase HF treated surfaces. Samples treated with gas phase HF inhibit growth. Inhibition is caused by residual F atoms that passivate the surface and by surface poisoning due to the thicker carbon film deposited during the first pulse of TMA. On InGaAs covered by native oxide, the first TMA pulse deposits 9 Å of aluminum oxide, and reaches saturation at 13 Å after 15 pulses of TMA. The film grows by scavenging oxygen from the substrate oxides. Substrate oxides are reduced by the first pulse of TMA even at 0°C. At 0°C, on a 9 Å thick Ga-rich oxide surface, 1 pulse of TMA mainly physisorbs and a limited amount of aluminum oxide is deposited. At 0°C, 110°C, and 170°C, more aluminum oxide is deposited on surfaces initially containing As oxide, and larger binding energy (BE) shifts of the O 1s peak are observed compared to surfaces that contain Ga oxides only, showing that As oxides improve the nucleation of Al₂O₃.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectGaAsen_US
dc.subjectInGaAsen_US
dc.subjectin situen_US
dc.subjectnucleationen_US
dc.subjectChemical Engineeringen_US
dc.subjectALDen_US
dc.subjectaluminaen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineChemical Engineeringen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorMuscat, Anthony J.en_US
dc.contributor.committeememberSorooshian, Arminen_US
dc.contributor.committeememberMars, Matthew M.en_US
dc.contributor.committeememberGervasio, Dominic F.en_US
dc.contributor.committeememberMuscat, Anthony J.en_US
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.