Subsurface modification in Si induced by nanosecond laser irradiation
type: CreativeWork
description: Semiconductor devices are pivotal to modern technology. These devices are batch produced on wafers which must be diced. Conventionally, dicing involves destroying the material between each chip, dictating a minimum spacing between modifications. It follows that eliminating this material loss will allow more chips to be created per wafer. This thesis examines subsurface modifications that form part of a dicing process with no material loss. Subsurface modifications can be induced by focussed pulsed laser irradiation when the photon energy is near or below the material's bandgap. Intensity dependent absorption is used to selectively modify the region near focus. This technique is useful both for technological applications and scientific investigation of material properties and laser-material interaction. This thesis examines columnar modifications created subsurface in Si wafers due to melting induced by nanosecond pulsed laser irradiation. The wafer dicing technique uses rows of closely spaced modifications that can preferentially guide crack propagation over the natural cleavage planes when the sample is cleaved. The modifications themselves are poorly characterised and it is this deficiency that this thesis seeks to address. The work examines both isolated modifications, where the laser-matter interaction can be probed, and closely spaced modifications, which can provide insight into the dicing process. Additionally, modifications created under several different laser conditions are investigated. Transmission electron microscopy is used to examine both the short and long axis of the modifications. Scanning electron microscopy and Raman microspectroscopy are also used. Detailed examination of the short axis of the modifications reveal a range of morphological features. These features can be explained by extending upon the literature of one-dimensional pulsed laser melting experiments into two-dimensions and conditions of higher cooling rates. Rapid, accelerating sol…
abstract: Semiconductor devices are pivotal to modern technology. These devices are batch produced on wafers which must be diced. Conventionally, dicing involves destroying the material between each chip, dictating a minimum spacing between modifications. It follows that eliminating this material loss will allow more chips to be created per wafer. This thesis examines subsurface modifications that form part of a dicing process with no material loss. Subsurface modifications can be induced by focussed pulsed laser irradiation when the photon energy is near or below the material's bandgap. Intensity dependent absorption is used to selectively modify the region near focus. This technique is useful both for technological applications and scientific investigation of material properties and laser-material interaction. This thesis examines columnar modifications created subsurface in Si wafers due to melting induced by nanosecond pulsed laser irradiation. The wafer dicing technique uses rows of closely spaced modifications that can preferentially guide crack propagation over the natural cleavage planes when the sample is cleaved. The modifications themselves are poorly characterised and it is this deficiency that this thesis seeks to address. The work examines both isolated modifications, where the laser-matter interaction can be probed, and closely spaced modifications, which can provide insight into the dicing process. Additionally, modifications created under several different laser conditions are investigated. Transmission electron microscopy is used to examine both the short and long axis of the modifications. Scanning electron microscopy and Raman microspectroscopy are also used. Detailed examination of the short axis of the modifications reveal a range of morphological features. These features can be explained by extending upon the literature of one-dimensional pulsed laser melting experiments into two-dimensions and conditions of higher cooling rates. Rapid, accelerating sol…
author: Smillie, Lachlan
language: en_AU
date published: 2020
date modified: 2026-07-24T00:54:51Z
provider: Australian National University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Australian National University

PropertyValue
property ID: Handle
value: http://hdl.handle.net/1885/201699