Effects of interface bonding and defects on boron diffusion at Si/SiO2 interface

We perform first-principles density functional calculations to find the migration pathway and barrier for B diffusion at the Si/SiO2 interface. For various interface models, in which crystalline α-quartz or amorphous silica (a-SiO2) is placed on Si, we examine stable and metastable configurations of...

Full description

Saved in:
Bibliographic Details
Published in:Journal of applied physics 2013-12, Vol.114 (22)
Main Authors: Kim, Geun-Myeong, Oh, Young Jun, Chang, K. J.
Format: Article
Language:English
Subjects:
Applied physics
Barriers
Bonding
Boron
Crystal defects
Defects
Diffusion barriers
First principles
Migration
Quartz
Silicon dioxide
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We perform first-principles density functional calculations to find the migration pathway and barrier for B diffusion at the Si/SiO2 interface. For various interface models, in which crystalline α-quartz or amorphous silica (a-SiO2) is placed on Si, we examine stable and metastable configurations of B-related defects which play a role in B diffusion. While a substitutional B alone is immobile in Si, it tends to diffuse to the interface via an interstitialcy mechanism in the presence of a self-interstitial and then changes into an interstitial B in oxide via a kick-out mechanism, leaving the self-interstitial at the interface. At the defect-free interface, where bridging O atoms are inserted to remove interface dangling bonds, an interstitial B prefers to intervene between the interface Si and bridging O atoms and subsequently diffuses through the hollow space or along the network of the Si-O-Si bonds in oxide. The overall migration barriers are calculated to be 2.02–2.12 eV at the Si/α-quartz interface, while they lie in the range of 2.04 ± 0.44 eV at the Si/a-SiO2 interface, similar to that in α-quartz. The migration pathway and barrier are not significantly affected by interface defects such as suboxide bond and O protrusion, while dangling bonds in the suboxide region can increase the migration barrier by about 1.5 eV. The result that the interface generally does not hinder the B diffusion from Si to SiO2 assists in understanding the underlying mechanism for B segregation which commonly occurs at the Si/SiO2 interface.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4844415