{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/85935"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/85935","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Pulsed Sheet Electron Beam Plasma-Assisted CVD of Silicon Films","abstract":"Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997.","abstract_html":"Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997.","abstract_has_math":false,"creators":["Shaheen, Mohammad A."],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Nuclear Engineering","degree_department":null,"school":null,"contributors":["Ruzic, David N."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-09-28T14:51:20Z","date_published":"2015-09-28T14:51:20Z","updated_at":"2026-07-22T22:26:26Z","subjects":["Engineering, Materials Science"],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(MiAaPQ)AAI9812834"],"render_values":[{"text":"(MiAaPQ)AAI9812834","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/85935","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Ruzic, David N."]},{"key":"dc:creator","label":"Author","values":["Shaheen, Mohammad A."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2015-09-28T14:51:20Z","10000-01-01","1997"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Nuclear Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Engineering, Materials Science"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/85935","(MiAaPQ)AAI9812834"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997.","Embargo set by: Seth Robbins for item 87216 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","307 p.","Pulsed Sheet Electron Beam Plasma-Assisted Chemical Vapor Deposition (PSEB-CVD) is a novel method of thin film deposition which is a variant on the conventional PECVD and an alternative to remote PECVD. PSEB-CVD uses a pulsed electron beam generated plasma, whose dimension is confined to a narrow sheet that passes over the substrate at a controllable height. Variations in plasma pulse width, cathode voltage, sheet beam-to-substrate distance, gas type and pressure can vary the type and energy of the species arriving at the substrate. Specifically, the ratio of $\\rm SiH\\sb3/SiH\\sb2$ flux to the substrate can be increased by a factor of 10 by placing the wafer at least 5 cm from the sheet beam and increased by 3 orders of magnitude by operating the plasma at a 10% duty cycle. The increased $\\rm SiH\\sb3/SiH\\sb2$ flux ratio results in better film quality due to the larger surface mobility of SiH$\\sb3$ when compared to SiH$\\sb2.$ This improvement, however, is accompanied by a linear decrease in deposition rate, from 25 A/min for the dc case without a sheet beam, to 5 A/m for the 0.5 duty cycle case with the wafer at 5 cm from the substrate. A system based on the PSEB-CVD principles was designed and built to allow the creation of a sheet e-beam at a variable distance from a heated substrate in a 5% silane/He plasma. Also, a plasma-pulsing circuit that can deliver square pulses of widely varying shapes has been built and used to create a pulsed e-beam plasma with varying pulsing conditions. A model of the sheet e-beam plasma kinetics, silane chemistry and surface deposition is used to guide the choice of the experimental parameters so as to effectively select a specific radical for deposition. The pulsed plasma was characterized with Langmuir probe analysis which showed that for the case of a He plasma there was a sharp increase in electron density immediately after the pulse was turned off. For the pulsed silane/He plasma, this effect was not as large, but unlike the He plasma, the floating potential increased for a few ms's after initiating the pulse. The silane/He plasma may have had a strong e-beam component. A recipe was developed for the optimum operating conditions of the PSEB-CVD system based on an analysis of the system operating under a variety of conditions. Growth of Si films in the 100-600 A thickness range was demonstrated as a proof of principle of the PSEB-CVD method. The films were characterized for uniformity, impurity content and crystallinity by a variety of surface analysis techniques including Profilometer, AES, EBSD, SEM, XRD and AFM. The films grown were found to be pure to a detection limit of 0.2%. Diffraction data, as well as grain surface morphology, were used to characterize crystallinity. The films deposited without a sheet beam were found to be amorphous, while the ones grown in a sheet beam were partially polycrystalline (30%). An x-ray diffraction analysis on films deposited in pulsed (0.5 duty cycle) sheet beam (substrate height = 5 cm) indicated the possibility that the films could be preferentially oriented. The films were typically grown at temperatures of 370$\\sp\\circ$C and 250 mTorr pressure. The Nm uniformity was also greatly improved with the use of the sheet e-beam configuration. The improved crystallinity confirms that deposition quality is improved as a result of beam confinement and plasma pulsing.","Made available in DSpace on 2015-09-28T14:51:20Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 9812834.pdf: 10660479 bytes, checksum: e8742b6a2c994c8fc4328e487737d69f (MD5) Previous issue date: 1997"]},{"key":"dc:title","label":"Title","values":["Pulsed Sheet Electron Beam Plasma-Assisted CVD of Silicon Films"]}]}],"canonical_facts":{"dc:contributor":["Ruzic, David N."],"dc:creator":["Shaheen, Mohammad A."],"dc:date":["2015-09-28T14:51:20Z","10000-01-01","1997"],"dc:description":["Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997.","Embargo set by: Seth Robbins for item 87216 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","307 p.","Pulsed Sheet Electron Beam Plasma-Assisted Chemical Vapor Deposition (PSEB-CVD) is a novel method of thin film deposition which is a variant on the conventional PECVD and an alternative to remote PECVD. PSEB-CVD uses a pulsed electron beam generated plasma, whose dimension is confined to a narrow sheet that passes over the substrate at a controllable height. Variations in plasma pulse width, cathode voltage, sheet beam-to-substrate distance, gas type and pressure can vary the type and energy of the species arriving at the substrate. Specifically, the ratio of $\\rm SiH\\sb3/SiH\\sb2$ flux to the substrate can be increased by a factor of 10 by placing the wafer at least 5 cm from the sheet beam and increased by 3 orders of magnitude by operating the plasma at a 10% duty cycle. The increased $\\rm SiH\\sb3/SiH\\sb2$ flux ratio results in better film quality due to the larger surface mobility of SiH$\\sb3$ when compared to SiH$\\sb2.$ This improvement, however, is accompanied by a linear decrease in deposition rate, from 25 A/min for the dc case without a sheet beam, to 5 A/m for the 0.5 duty cycle case with the wafer at 5 cm from the substrate. A system based on the PSEB-CVD principles was designed and built to allow the creation of a sheet e-beam at a variable distance from a heated substrate in a 5% silane/He plasma. Also, a plasma-pulsing circuit that can deliver square pulses of widely varying shapes has been built and used to create a pulsed e-beam plasma with varying pulsing conditions. A model of the sheet e-beam plasma kinetics, silane chemistry and surface deposition is used to guide the choice of the experimental parameters so as to effectively select a specific radical for deposition. The pulsed plasma was characterized with Langmuir probe analysis which showed that for the case of a He plasma there was a sharp increase in electron density immediately after the pulse was turned off. For the pulsed silane/He plasma, this effect was not as large, but unlike the He plasma, the floating potential increased for a few ms's after initiating the pulse. The silane/He plasma may have had a strong e-beam component. A recipe was developed for the optimum operating conditions of the PSEB-CVD system based on an analysis of the system operating under a variety of conditions. Growth of Si films in the 100-600 A thickness range was demonstrated as a proof of principle of the PSEB-CVD method. The films were characterized for uniformity, impurity content and crystallinity by a variety of surface analysis techniques including Profilometer, AES, EBSD, SEM, XRD and AFM. The films grown were found to be pure to a detection limit of 0.2%. Diffraction data, as well as grain surface morphology, were used to characterize crystallinity. The films deposited without a sheet beam were found to be amorphous, while the ones grown in a sheet beam were partially polycrystalline (30%). An x-ray diffraction analysis on films deposited in pulsed (0.5 duty cycle) sheet beam (substrate height = 5 cm) indicated the possibility that the films could be preferentially oriented. The films were typically grown at temperatures of 370$\\sp\\circ$C and 250 mTorr pressure. The Nm uniformity was also greatly improved with the use of the sheet e-beam configuration. The improved crystallinity confirms that deposition quality is improved as a result of beam confinement and plasma pulsing.","Made available in DSpace on 2015-09-28T14:51:20Z (GMT). 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