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Transmission of Free Radicals through and Damage to Freestanding Single and Multilayer Dielectric Film.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Transmission of Free Radicals through and Damage to Freestanding Single and Multilayer Dielectric Film./
Author:	Choudhury, Faraz Anwar.
Description:	1 online resource (171 pages)
Notes:	Source: Dissertation Abstracts International, Volume: 78-09(E), Section: B.
Subject:	Electrical engineering. -
Online resource:	click for full text (PQDT)
ISBN:	9781369702477

Transmission of Free Radicals through and Damage to Freestanding Single and Multilayer Dielectric Film.
Choudhury, Faraz Anwar.

Transmission of Free Radicals through and Damage to Freestanding Single and Multilayer Dielectric Film. - 1 online resource (171 pages)

Source: Dissertation Abstracts International, Volume: 78-09(E), Section: B.

Thesis (Ph.D.)--The University of Wisconsin - Madison, 2017.

Includes bibliographical references

A high concentration of free radicals is present in many processing plasmas, which affects the processing conditions and the properties of materials exposed to the plasma. Measuring the types and concentrations of free radicals present in the plasma is critical in order to determine their effects on the materials being processed. Current methods for detecting free radicals in a plasma require multiple expensive and bulky instruments, complex setups and often modifications to the plasma reactor. In this work, we present a simple technique that detects reactive-oxygen radicals incident on a surface from a plasma. The measurements are made using a fluorophore dye that is commonly used in biological and cellular systems for assay labeling in liquids. Using fluorometric analysis, it was found that the fluorophore reacts with oxygen radicals incident from the plasma, which is indicated by degradation of its fluorescence. As plasma power was increased, the quenching of the fluorescence significantly increased. Both immobilized and non-immobilized fluorophore dyes were used and the results indicate that both states function effectively under vacuum conditions. Using radical-sensitive dyes and free-standing films, the transmission of oxygen radicals through silicon nitride and silicon dioxide dielectric films is measured and their absorption lengths are determined. The absorption lengths were found to be 33, 37 and 40 nm for 15, 30 and 45-minute oxygen plasma exposures respectively. FTIR and XRR measurements show that a silicon oxynitride-like layer forms on the surface of the film which has a lower density than silicon nitride. The increase in absorption length with plasma-exposure time is attributed to the formation of the surface layer. In silicon dioxide films, the absorption length of oxygen radicals was found to be ~70 nm after 20 minutes of plasma exposure. After 30 minutes of plasma exposure under the same conditions, the absorption length was reduced to ~66 nm. XRR and FTIR measurements both reveal that the oxygen plasma exposure leads to surface oxidation of the silicon dioxide film and the formation of a denser surface layer which restricts the transmission of the radicals through the film. It was found that the extent of modification of the film partially depends on the radical dose. The calculated enthalpies of the reactions show that they are all exothermic reactions, however, the radicals need enough energy to overcome the activation energy for the reaction to take place.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9781369702477Subjects--Topical Terms:

596380
Electrical engineering.
Index Terms--Genre/Form:

554714
Electronic books.

Transmission of Free Radicals through and Damage to Freestanding Single and Multilayer Dielectric Film.
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100 1 $a Choudhury, Faraz Anwar. $3 1187244
245 1 0 $a Transmission of Free Radicals through and Damage to Freestanding Single and Multilayer Dielectric Film.
264 0 $c 2017
300 $a 1 online resource (171 pages)
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500 $a Source: Dissertation Abstracts International, Volume: 78-09(E), Section: B.
500 $a Adviser: Juda L. Shohet.
502 $a Thesis (Ph.D.)--The University of Wisconsin - Madison, 2017.
504 $a Includes bibliographical references
520 $a A high concentration of free radicals is present in many processing plasmas, which affects the processing conditions and the properties of materials exposed to the plasma. Measuring the types and concentrations of free radicals present in the plasma is critical in order to determine their effects on the materials being processed. Current methods for detecting free radicals in a plasma require multiple expensive and bulky instruments, complex setups and often modifications to the plasma reactor. In this work, we present a simple technique that detects reactive-oxygen radicals incident on a surface from a plasma. The measurements are made using a fluorophore dye that is commonly used in biological and cellular systems for assay labeling in liquids. Using fluorometric analysis, it was found that the fluorophore reacts with oxygen radicals incident from the plasma, which is indicated by degradation of its fluorescence. As plasma power was increased, the quenching of the fluorescence significantly increased. Both immobilized and non-immobilized fluorophore dyes were used and the results indicate that both states function effectively under vacuum conditions. Using radical-sensitive dyes and free-standing films, the transmission of oxygen radicals through silicon nitride and silicon dioxide dielectric films is measured and their absorption lengths are determined. The absorption lengths were found to be 33, 37 and 40 nm for 15, 30 and 45-minute oxygen plasma exposures respectively. FTIR and XRR measurements show that a silicon oxynitride-like layer forms on the surface of the film which has a lower density than silicon nitride. The increase in absorption length with plasma-exposure time is attributed to the formation of the surface layer. In silicon dioxide films, the absorption length of oxygen radicals was found to be ~70 nm after 20 minutes of plasma exposure. After 30 minutes of plasma exposure under the same conditions, the absorption length was reduced to ~66 nm. XRR and FTIR measurements both reveal that the oxygen plasma exposure leads to surface oxidation of the silicon dioxide film and the formation of a denser surface layer which restricts the transmission of the radicals through the film. It was found that the extent of modification of the film partially depends on the radical dose. The calculated enthalpies of the reactions show that they are all exothermic reactions, however, the radicals need enough energy to overcome the activation energy for the reaction to take place.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2018
538 $a Mode of access: World Wide Web
650 4 $a Electrical engineering. $3 596380
650 4 $a Plasma physics. $2 bicssc $3 1030958
650 4 $a Materials science. $3 557839
655 7 $a Electronic books. $2 local $3 554714
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690 $a 0759
690 $a 0794
710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a The University of Wisconsin - Madison. $b Electrical Engineering. $3 1178889
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10266433 $z click for full text (PQDT)