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Creation and Optimisation of Plasma Etch Processes for the Manufacture of Silicon Microstructures / CHRISTOPHER BOLTON

Swansea University Author: CHRISTOPHER BOLTON

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DOI (Published version): 10.23889/SUthesis.63222

Abstract

Microneedles are an area of growing interest for applications in transdermal delivery. Small, minimally invasive medical or cosmetic devices, microneedles are intended to penetrate the skin’s outer protective layer (stratum corneum) to facilitate delivery of active formulations into the skin. Delive...

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Published: Swansea, Wales, UK 2023
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Guy, Owen J. ; Sharma, Sanjiv.
URI: https://cronfa.swan.ac.uk/Record/cronfa63222
first_indexed 2023-04-25T10:20:54Z
last_indexed 2024-11-15T18:01:10Z
id cronfa63222
recordtype RisThesis
fullrecord <?xml version="1.0"?><rfc1807><datestamp>2023-09-28T15:01:09.7942472</datestamp><bib-version>v2</bib-version><id>63222</id><entry>2023-04-20</entry><title>Creation and Optimisation of Plasma Etch Processes for the Manufacture of Silicon Microstructures</title><swanseaauthors><author><sid>da0d96a0d92538848c763cfe479f96c4</sid><firstname>CHRISTOPHER</firstname><surname>BOLTON</surname><name>CHRISTOPHER BOLTON</name><active>true</active><ethesisStudent>false</ethesisStudent></author></swanseaauthors><date>2023-04-20</date><abstract>Microneedles are an area of growing interest for applications in transdermal delivery. Small, minimally invasive medical or cosmetic devices, microneedles are intended to penetrate the skin&#x2019;s outer protective layer (stratum corneum) to facilitate delivery of active formulations into the skin. Delivery of solution via microneedles has the benefits associated with hypodermic injection, i.e. avoiding the first-pass metabolism systems, with the added advantages of painless delivery and dose sparing from the reduced solution volumes required.Advancements in semiconductor processing technologies and equipment have enabled the creation of devices and structures that could not have been fabricated in the past. This is also true for the fabrication of microneedles, where previous manufacturing methods have relied on hazardous chemicals such as Hydrofluoric Acid and Potassium Hydroxide to create the sharp tip of the needle, required to reduce insertion force.In this thesis, the realisation of a hollow bevelled silicon microneedle fabricated using only plasma processing techniques is presented, providing a route to scalable manufacture of high-performance, sharp-tipped microneedles. The microneedle fabrication process consists of three main etch steps in the process flow to create hollow structures. For each of the Bevel, Bore, and Shaft processes the development and optimisation is detailed. Throughout the process development, several unexpected processing issues were encountered, including depth non-uniformity, &#x201C;notching&#x201D;, and &#x201C;silicon grass&#x201D;. Investigations have been performed to determine the root cause of each issue and fine-tune processes to optimise the final devices. A discussion of the process hardware is also presented, with reference to the benefits for each specific application process.Following development and optimisation of each individual process, the Bevel, Bore, and Shaft processes were integrated in the manufacturing flow to create the final hollow silicon microneedle device. Issues arising from the combination of the three processes have been investigated, resolved, and optimised. This includes the conception and execution of a novel process for the plasma smoothing of an angled silicon surface, which improved the quality of lithography on the non-planar bevel surface and minimised grass formation.Preliminary testing, undertaken to assess the suitability of these devices for transdermal use, included mechanical fracture force, skin penetration, and injection testing. The microneedles were found to be strong enough to remain intact during insertion, and demonstrate successful penetration and injection through the stratum corneum and into the deeper skin layers.</abstract><type>E-Thesis</type><journal/><volume/><journalNumber/><paginationStart/><paginationEnd/><publisher/><placeOfPublication>Swansea, Wales, UK</placeOfPublication><isbnPrint/><isbnElectronic/><issnPrint/><issnElectronic/><keywords>Microneedle, Silicon, Hollow, Plasma, Etch, Drug Delivery, Vaccine, Cosmetic, Manufacturing, Nanotechnology, Biomedical, Semiconductor.</keywords><publishedDay>25</publishedDay><publishedMonth>4</publishedMonth><publishedYear>2023</publishedYear><publishedDate>2023-04-25</publishedDate><doi>10.23889/SUthesis.63222</doi><url/><notes>A selection of third party content is redacted or is partially redacted from this thesis due to copyright restrictions/to protect the commercial interests of the sponsor company.</notes><college>COLLEGE NANME</college><CollegeCode>COLLEGE CODE</CollegeCode><institution>Swansea University</institution><supervisor>Guy, Owen J. ; Sharma, Sanjiv.</supervisor><degreelevel>Doctoral</degreelevel><degreename>Ph.D</degreename><degreesponsorsfunders>SPTS Technologies Ltd.</degreesponsorsfunders><apcterm/><funders/><projectreference/><lastEdited>2023-09-28T15:01:09.7942472</lastEdited><Created>2023-04-20T14:40:41.4689986</Created><path><level id="1">Faculty of Science and Engineering</level><level id="2">School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Electronic and Electrical Engineering</level></path><authors><author><firstname>CHRISTOPHER</firstname><surname>BOLTON</surname><order>1</order></author></authors><documents><document><filename>63222__27181__46d6805d692c4dad957e1bd1f2409973.pdf</filename><originalFilename>2023_Bolton_C.final.63222.pdf</originalFilename><uploaded>2023-04-25T11:39:00.5262290</uploaded><type>Output</type><contentLength>8536971</contentLength><contentType>application/pdf</contentType><version>Redacted version - open access</version><cronfaStatus>true</cronfaStatus><documentNotes>Copyright: The Author, Christopher Bolton, 2023</documentNotes><copyrightCorrect>true</copyrightCorrect><language>eng</language></document></documents><OutputDurs/></rfc1807>
spelling 2023-09-28T15:01:09.7942472 v2 63222 2023-04-20 Creation and Optimisation of Plasma Etch Processes for the Manufacture of Silicon Microstructures da0d96a0d92538848c763cfe479f96c4 CHRISTOPHER BOLTON CHRISTOPHER BOLTON true false 2023-04-20 Microneedles are an area of growing interest for applications in transdermal delivery. Small, minimally invasive medical or cosmetic devices, microneedles are intended to penetrate the skin’s outer protective layer (stratum corneum) to facilitate delivery of active formulations into the skin. Delivery of solution via microneedles has the benefits associated with hypodermic injection, i.e. avoiding the first-pass metabolism systems, with the added advantages of painless delivery and dose sparing from the reduced solution volumes required.Advancements in semiconductor processing technologies and equipment have enabled the creation of devices and structures that could not have been fabricated in the past. This is also true for the fabrication of microneedles, where previous manufacturing methods have relied on hazardous chemicals such as Hydrofluoric Acid and Potassium Hydroxide to create the sharp tip of the needle, required to reduce insertion force.In this thesis, the realisation of a hollow bevelled silicon microneedle fabricated using only plasma processing techniques is presented, providing a route to scalable manufacture of high-performance, sharp-tipped microneedles. The microneedle fabrication process consists of three main etch steps in the process flow to create hollow structures. For each of the Bevel, Bore, and Shaft processes the development and optimisation is detailed. Throughout the process development, several unexpected processing issues were encountered, including depth non-uniformity, “notching”, and “silicon grass”. Investigations have been performed to determine the root cause of each issue and fine-tune processes to optimise the final devices. A discussion of the process hardware is also presented, with reference to the benefits for each specific application process.Following development and optimisation of each individual process, the Bevel, Bore, and Shaft processes were integrated in the manufacturing flow to create the final hollow silicon microneedle device. Issues arising from the combination of the three processes have been investigated, resolved, and optimised. This includes the conception and execution of a novel process for the plasma smoothing of an angled silicon surface, which improved the quality of lithography on the non-planar bevel surface and minimised grass formation.Preliminary testing, undertaken to assess the suitability of these devices for transdermal use, included mechanical fracture force, skin penetration, and injection testing. The microneedles were found to be strong enough to remain intact during insertion, and demonstrate successful penetration and injection through the stratum corneum and into the deeper skin layers. E-Thesis Swansea, Wales, UK Microneedle, Silicon, Hollow, Plasma, Etch, Drug Delivery, Vaccine, Cosmetic, Manufacturing, Nanotechnology, Biomedical, Semiconductor. 25 4 2023 2023-04-25 10.23889/SUthesis.63222 A selection of third party content is redacted or is partially redacted from this thesis due to copyright restrictions/to protect the commercial interests of the sponsor company. COLLEGE NANME COLLEGE CODE Swansea University Guy, Owen J. ; Sharma, Sanjiv. Doctoral Ph.D SPTS Technologies Ltd. 2023-09-28T15:01:09.7942472 2023-04-20T14:40:41.4689986 Faculty of Science and Engineering School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Electronic and Electrical Engineering CHRISTOPHER BOLTON 1 63222__27181__46d6805d692c4dad957e1bd1f2409973.pdf 2023_Bolton_C.final.63222.pdf 2023-04-25T11:39:00.5262290 Output 8536971 application/pdf Redacted version - open access true Copyright: The Author, Christopher Bolton, 2023 true eng
title Creation and Optimisation of Plasma Etch Processes for the Manufacture of Silicon Microstructures
spellingShingle Creation and Optimisation of Plasma Etch Processes for the Manufacture of Silicon Microstructures
CHRISTOPHER BOLTON
title_short Creation and Optimisation of Plasma Etch Processes for the Manufacture of Silicon Microstructures
title_full Creation and Optimisation of Plasma Etch Processes for the Manufacture of Silicon Microstructures
title_fullStr Creation and Optimisation of Plasma Etch Processes for the Manufacture of Silicon Microstructures
title_full_unstemmed Creation and Optimisation of Plasma Etch Processes for the Manufacture of Silicon Microstructures
title_sort Creation and Optimisation of Plasma Etch Processes for the Manufacture of Silicon Microstructures
author_id_str_mv da0d96a0d92538848c763cfe479f96c4
author_id_fullname_str_mv da0d96a0d92538848c763cfe479f96c4_***_CHRISTOPHER BOLTON
author CHRISTOPHER BOLTON
author2 CHRISTOPHER BOLTON
format E-Thesis
publishDate 2023
institution Swansea University
doi_str_mv 10.23889/SUthesis.63222
college_str Faculty of Science and Engineering
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hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Electronic and Electrical Engineering{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Electronic and Electrical Engineering
document_store_str 1
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description Microneedles are an area of growing interest for applications in transdermal delivery. Small, minimally invasive medical or cosmetic devices, microneedles are intended to penetrate the skin’s outer protective layer (stratum corneum) to facilitate delivery of active formulations into the skin. Delivery of solution via microneedles has the benefits associated with hypodermic injection, i.e. avoiding the first-pass metabolism systems, with the added advantages of painless delivery and dose sparing from the reduced solution volumes required.Advancements in semiconductor processing technologies and equipment have enabled the creation of devices and structures that could not have been fabricated in the past. This is also true for the fabrication of microneedles, where previous manufacturing methods have relied on hazardous chemicals such as Hydrofluoric Acid and Potassium Hydroxide to create the sharp tip of the needle, required to reduce insertion force.In this thesis, the realisation of a hollow bevelled silicon microneedle fabricated using only plasma processing techniques is presented, providing a route to scalable manufacture of high-performance, sharp-tipped microneedles. The microneedle fabrication process consists of three main etch steps in the process flow to create hollow structures. For each of the Bevel, Bore, and Shaft processes the development and optimisation is detailed. Throughout the process development, several unexpected processing issues were encountered, including depth non-uniformity, “notching”, and “silicon grass”. Investigations have been performed to determine the root cause of each issue and fine-tune processes to optimise the final devices. A discussion of the process hardware is also presented, with reference to the benefits for each specific application process.Following development and optimisation of each individual process, the Bevel, Bore, and Shaft processes were integrated in the manufacturing flow to create the final hollow silicon microneedle device. Issues arising from the combination of the three processes have been investigated, resolved, and optimised. This includes the conception and execution of a novel process for the plasma smoothing of an angled silicon surface, which improved the quality of lithography on the non-planar bevel surface and minimised grass formation.Preliminary testing, undertaken to assess the suitability of these devices for transdermal use, included mechanical fracture force, skin penetration, and injection testing. The microneedles were found to be strong enough to remain intact during insertion, and demonstrate successful penetration and injection through the stratum corneum and into the deeper skin layers.
published_date 2023-04-25T06:58:45Z
_version_ 1850741176112513024
score 11.08895

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