Formation of Aminosilane and Thiol Monolayers on Semiconductor Surfaces and Bulk Wet Etching of III--V Semiconductors

Persistent Link:
http://hdl.handle.net/10150/255196
Title:
Formation of Aminosilane and Thiol Monolayers on Semiconductor Surfaces and Bulk Wet Etching of III--V Semiconductors
Author:
Jain, Rahul
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.
Embargo:
Release after 20-Feb-2013
Abstract:
Continuous scaling down of the dimensions of electronic devices has made present day computers more powerful. In the front end of line, the minimum lateral dimensions in a transistor have shrunk from 45 nm in 2007 to 22 nm currently, and the gate oxide film thickness is two to three monolayers. This reduction in dimensions makes surface preparation an increasingly important part of the device fabrication process. The atoms or molecules that terminate surfaces function as passivation layers, diffusion barriers, and nucleation layers. In the back end of line, metal layers are deposited to connect transistors. We demonstrate a reproducible process that deposits a monolayer of aminopropyltrimethoxysilane molecules less than one nanometer thick on a silicon dioxide surface. The monolayer contains a high density of amine groups that can be used to deposit Pd and Ni and subsequently Co and Cu to serve as the nucleation layer in an electroless metal deposition process. Because of the shrinking device dimensions, there is a need to find new transistor channel materials that have high electron mobilities along with narrow band gaps to reduce power consumption. Compound III--V channel materials are candidates to enable increased performance and reduced power consumption at the current scaled geometries. But many challenges remain for such high mobility materials to be realized in high volume manufacturing. For instance, low defect density (1E7 /cm²) III--V and Ge on Si is the most fundamental issue to overcome before high mobility materials become practical. Unlike Si, dry etching of III-V semiconductor surfaces is believed to be difficult and uncontrollable. Therefore, new wet etching chemistries are needed. Si has been known to passivate by etching in hydrofluoric acid, but similar treatments on III--Vs are known to temporarily hydrogen passivate the surfaces. However, any subsequent exposure to the ambient reoxidizes the surface, resulting in a chemically unstable and high defect density interface. This work compares old and new wet etching chemistries and investigates new methods of passivating the III--V semiconductors.
Type:
text; Electronic Dissertation
Keywords:
Self-assembled monolayers; Semiconductors; Surface Chemistry; Wet etching; Chemical Engineering; III-V; Passivation
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.titleFormation of Aminosilane and Thiol Monolayers on Semiconductor Surfaces and Bulk Wet Etching of III--V Semiconductorsen_US
dc.creatorJain, Rahulen_US
dc.contributor.authorJain, Rahulen_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.releaseRelease after 20-Feb-2013en_US
dc.description.abstractContinuous scaling down of the dimensions of electronic devices has made present day computers more powerful. In the front end of line, the minimum lateral dimensions in a transistor have shrunk from 45 nm in 2007 to 22 nm currently, and the gate oxide film thickness is two to three monolayers. This reduction in dimensions makes surface preparation an increasingly important part of the device fabrication process. The atoms or molecules that terminate surfaces function as passivation layers, diffusion barriers, and nucleation layers. In the back end of line, metal layers are deposited to connect transistors. We demonstrate a reproducible process that deposits a monolayer of aminopropyltrimethoxysilane molecules less than one nanometer thick on a silicon dioxide surface. The monolayer contains a high density of amine groups that can be used to deposit Pd and Ni and subsequently Co and Cu to serve as the nucleation layer in an electroless metal deposition process. Because of the shrinking device dimensions, there is a need to find new transistor channel materials that have high electron mobilities along with narrow band gaps to reduce power consumption. Compound III--V channel materials are candidates to enable increased performance and reduced power consumption at the current scaled geometries. But many challenges remain for such high mobility materials to be realized in high volume manufacturing. For instance, low defect density (1E7 /cm²) III--V and Ge on Si is the most fundamental issue to overcome before high mobility materials become practical. Unlike Si, dry etching of III-V semiconductor surfaces is believed to be difficult and uncontrollable. Therefore, new wet etching chemistries are needed. Si has been known to passivate by etching in hydrofluoric acid, but similar treatments on III--Vs are known to temporarily hydrogen passivate the surfaces. However, any subsequent exposure to the ambient reoxidizes the surface, resulting in a chemically unstable and high defect density interface. This work compares old and new wet etching chemistries and investigates new methods of passivating the III--V semiconductors.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectSelf-assembled monolayersen_US
dc.subjectSemiconductorsen_US
dc.subjectSurface Chemistryen_US
dc.subjectWet etchingen_US
dc.subjectChemical Engineeringen_US
dc.subjectIII-Ven_US
dc.subjectPassivationen_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.committeememberGuzman, Roberto Z.en_US
dc.contributor.committeememberSorooshian, Arminen_US
dc.contributor.committeememberLynch, David C.en_US
dc.contributor.committeememberMars, Matthew M.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.