Thesis (MScEng)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: High-temperature (HTc) SQUID magnetometers are used in the biomedical field of magnetocardiography
(MCG). The use of MCG enables a much earlier diagnosis of potentially dangerous
conditions than the use of electrocardiography (EeG). For the use of MCG, high-quality
HTc SQUIDs are necessary. These SQUIDs can only be realised if the design and fabrication
processes are well defined and understood. In this thesis an extensive literature review on the
design process explains all the concepts necessary to understand and design a high-quality HTc
SQUID. Then the fabrication process is redefined and characterised.
The SQUIDs are fabricated with YBCO thin films on MgO substrates. The relevant steps
in the process are the pulsed laser deposition (PLD), UV lithography and argon ion milling.
The characterisation of the fabrication process is based on a statistical method called Design
of Experiment (DOE). This enables more information to be obtained about the fabrication
process than before. For the PLO process the important parameters are determined and an
initial optimisation is done. During the characterisation process it is proven that the use of
ozone during PLO has a positive effect on the quality of the YBCO thin film. On the PLD
apparatus the substrate heater and laser-beam profile is improved. The UV lithography process
is analysed and a DOE is proposed for optimisation. A temperature bath is added to the process
to enable better reproducibility. An rf multicusp ion mill is built for argon-ion milling, this
device is tested and shown to provide the required etching capability. / AFRIKAANSE OPSOMMING: Hoë-temperatuur (HTc) SQUID magnetometers word in die biomediese rigting vir magnetokardiografie
(MKG) gebruik. Met MKG kan 'n mens potensieel gevaarlike toestande heelwat
vroeër diagnoseer as wat moontlik is met elektrokardiografie (EKG). HTc SQUIDs van hoë
kwaliteit word benodig vir MKG. Sulke SQUIDs kan slegs vervaardig word as die vervaardiging
en ontwerpsprosesse goed gedefinieer en verstaan word. In hierdie tesis verduidelik 'n omvattende
literatuurstudie oor die ontwerpsproses al die konsepte wat nodig is om 'n SQUID van
hoë kwaliteit te verstaan en te ontwerp. Verder word die vervaardigingsproses geherdefinieer
en gekarakteriseer.
Die SQUIDs word vervaardig met YBCO-dunfilm op MgO-substrate. Die relevante stappe
tydens die vervaardiging is: gepulseerde laser deposisie (PLO), UV-litografie en argon-ioonstraling.
Die karakterisering van die vervaardigingsproses is gebaseer op 'n statistiese metode
genaamd "Design of Experiment" (DOE). Hierdie metode laat 'n mens toe om meer inligting
oor die proses te verkry as wat voorheen moontlik was. Gedurende die karakterisering
word bewys dat die gebruik van osoon gedurende die PLO-proses 'n positiewe invloed op die
kwaliteit van die YBCO-dunfilm het. Die PLO-apparaat se substraatverwarmer en laserstraalprofiel
word verbeter. Die UV-litografieproses word geanaliseer en 'n DOE word voorgestel
vir die optimisering daarvan. Daar word 'n temperatuurbad by die proses gevoeg om die herhaalbaarheid
te verbeter. 'n "Rf multicusp ion mill" word gebou, die toestel word getoets en
daar word aangetoon dat dit die nodige etsvermoë het.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52828 |
| Date | 12 1900 |
| Creators | Rottier, P. A. (Pieter Adriaan) |
| Contributors | Perold, W. J., Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 212 p. : ill. |
| Rights | Stellenbosch University |
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