Calcium copper titanium oxide thin films for microelectronic applications

Detalhes bibliográficos
Autor(a) principal: Valente, João Pedro Mire Dores Pulido
Data de Publicação: 2010
Tipo de documento: Dissertação
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10773/7612
Resumo: Recent research has shown that the perovskite-related body-centred cubic material CaCu3Ti4O12 (CCTO) exhibit extraordinarily giant dielectric constant at room temperature (ε ≈ 104-105). Besides, these high dielectric constants were found to be nearly constant in the temperature range between 100 and 500K [1, 2]; which makes it even more attractive from the technological point of view. These properties are very important for device implementation and make CCTO a promising candidate for microelectronic applications (like decoupling capacitors, random access memories), microwave devices (for applications in mobile phones), antennas (for example, planar micro-strip antenna on CCTO substrate for 3-GHz operation) [3]. In the microelectronics device field, homogeneous and smooth thin films with colossal dielectric constant and with low dielectric loss are desirable. In the literature, only five reports on undoped CCTO films on silicon based substrates prepared by sol-gel method can be found. The majority of these authors did not present the dielectric and microstructural properties of the produced CCTO films. In this work, thin films of CCTO were prepared by sol-gel method by spin coating a nontoxic chemical solution on typical microelectronic substrates, Si (wafer) / SiO2 (300 nm) / TiO2 (20 nm) / Pt (150 nm). Two different precursor solutions were studied and optimized for film production. These two solutions differ mainly on the titanium precursor, although some preparation parameters where changed as well. One of the main objectives of the thesis was to develop nontoxic precursors for CSD method and accordingly, solutions were prepared without methoxyethanol (highly toxic). This constitutes a great improvement considering the good properties obtained for the 300-400 nm thick CCTO films prepared in this work: dielectric permittivity, ε of 500 and dielectric loss, tan of 0.19, for films derived from titanium butoxide precursor solutions (BUT-CCTO) and ε ≈ 620 and dielectric loss 0.18 for those derived from titanium isopropoxide precursor solutions (ISO-CCTO), all values at 1 kHz. In literature, toxic precursor solution of CCTO leads to films with values for dielectric permittivity of 1000-2000 and dielectric loss between 0.5 – 0.04 [52]. Best reports on nontoxic solutions for spin coating method presented dielectric constant (≈ 150-250) and losses around 0.2-0.5 [45]. The physical properties of the films were characterised. The structural and microstructural characterization was conducted via X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). [CALCIUM COPPER TITANIUM OXIDE THIN FILMS FOR MICROELECTRONIC APPLICATIONS] 10 For the electrical characterization the dielectric constant and dielectric losses were measured at room temperature in the range 100 Hz-1 MHz. AFM microstructure and especially potential images, confirmed IBLC model for conduction, since grain and grain boundaries presented different potentials due to their different electrical behaviour. This result was obtained for every sample made with both solutions. Grain size has a considerable influence on the dielectric properties of the thin films. grain films present high dielectric constant and high dielectric loss. Small grain origins lower dielectric constant but also low dielectric loss. In this work and based on IBLC model, it was found that grain and high grain boundaries density will guarantee good permittivity according with [6, 9], although with grain size increase, grain boundaries density decrease. An intermediate stage for grain size must be achieved depending on the solution used. Considering the dielectric loss, it was found to respect mainly to grain boundaries. High density of grain boundaries promotes second phase segregation (TiO2) due to low temperature heat treatments and worst insulator behaviour [18,24]. For one side, high density will lower dielectric loss confirming [6,13], on the other side, second phase segregation will increase it, as reported in [18, 24]. A compromise between the capacity of the semiconductor grains to admit charges and the resistivity of the insulator grain boundaries must be achieved to obtain good quality CCTO thin films. The admission of charges by the grain is controlled by the grain size (heat treatment procedure) meanwhile the current density of the grain boundaries is controlled by second phase segregation (solution procedure) and grain boundaries density (heat treatment procedure). As a final output of this work a new non-toxic precursor solution was developed as an alternative way for preparing CCTO thin films of high dielectric constant for microelectronic applications.
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spelling Calcium copper titanium oxide thin films for microelectronic applicationsCiência dos materiaisFilmes finosRevestimentos protectoresÓxidos metálicosCobreTitânioMicroelectrónica - MateriaisRecent research has shown that the perovskite-related body-centred cubic material CaCu3Ti4O12 (CCTO) exhibit extraordinarily giant dielectric constant at room temperature (ε ≈ 104-105). Besides, these high dielectric constants were found to be nearly constant in the temperature range between 100 and 500K [1, 2]; which makes it even more attractive from the technological point of view. These properties are very important for device implementation and make CCTO a promising candidate for microelectronic applications (like decoupling capacitors, random access memories), microwave devices (for applications in mobile phones), antennas (for example, planar micro-strip antenna on CCTO substrate for 3-GHz operation) [3]. In the microelectronics device field, homogeneous and smooth thin films with colossal dielectric constant and with low dielectric loss are desirable. In the literature, only five reports on undoped CCTO films on silicon based substrates prepared by sol-gel method can be found. The majority of these authors did not present the dielectric and microstructural properties of the produced CCTO films. In this work, thin films of CCTO were prepared by sol-gel method by spin coating a nontoxic chemical solution on typical microelectronic substrates, Si (wafer) / SiO2 (300 nm) / TiO2 (20 nm) / Pt (150 nm). Two different precursor solutions were studied and optimized for film production. These two solutions differ mainly on the titanium precursor, although some preparation parameters where changed as well. One of the main objectives of the thesis was to develop nontoxic precursors for CSD method and accordingly, solutions were prepared without methoxyethanol (highly toxic). This constitutes a great improvement considering the good properties obtained for the 300-400 nm thick CCTO films prepared in this work: dielectric permittivity, ε of 500 and dielectric loss, tan of 0.19, for films derived from titanium butoxide precursor solutions (BUT-CCTO) and ε ≈ 620 and dielectric loss 0.18 for those derived from titanium isopropoxide precursor solutions (ISO-CCTO), all values at 1 kHz. In literature, toxic precursor solution of CCTO leads to films with values for dielectric permittivity of 1000-2000 and dielectric loss between 0.5 – 0.04 [52]. Best reports on nontoxic solutions for spin coating method presented dielectric constant (≈ 150-250) and losses around 0.2-0.5 [45]. The physical properties of the films were characterised. The structural and microstructural characterization was conducted via X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). [CALCIUM COPPER TITANIUM OXIDE THIN FILMS FOR MICROELECTRONIC APPLICATIONS] 10 For the electrical characterization the dielectric constant and dielectric losses were measured at room temperature in the range 100 Hz-1 MHz. AFM microstructure and especially potential images, confirmed IBLC model for conduction, since grain and grain boundaries presented different potentials due to their different electrical behaviour. This result was obtained for every sample made with both solutions. Grain size has a considerable influence on the dielectric properties of the thin films. grain films present high dielectric constant and high dielectric loss. Small grain origins lower dielectric constant but also low dielectric loss. In this work and based on IBLC model, it was found that grain and high grain boundaries density will guarantee good permittivity according with [6, 9], although with grain size increase, grain boundaries density decrease. An intermediate stage for grain size must be achieved depending on the solution used. Considering the dielectric loss, it was found to respect mainly to grain boundaries. High density of grain boundaries promotes second phase segregation (TiO2) due to low temperature heat treatments and worst insulator behaviour [18,24]. For one side, high density will lower dielectric loss confirming [6,13], on the other side, second phase segregation will increase it, as reported in [18, 24]. A compromise between the capacity of the semiconductor grains to admit charges and the resistivity of the insulator grain boundaries must be achieved to obtain good quality CCTO thin films. The admission of charges by the grain is controlled by the grain size (heat treatment procedure) meanwhile the current density of the grain boundaries is controlled by second phase segregation (solution procedure) and grain boundaries density (heat treatment procedure). As a final output of this work a new non-toxic precursor solution was developed as an alternative way for preparing CCTO thin films of high dielectric constant for microelectronic applications.Universidade de Aveiro2012-03-30T14:26:47Z2010-01-01T00:00:00Z2010info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisapplication/pdfhttp://hdl.handle.net/10773/7612engValente, João Pedro Mire Dores Pulidoinfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2024-02-22T11:13:17Zoai:ria.ua.pt:10773/7612Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-20T02:45:17.047097Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Calcium copper titanium oxide thin films for microelectronic applications
title Calcium copper titanium oxide thin films for microelectronic applications
spellingShingle Calcium copper titanium oxide thin films for microelectronic applications
Valente, João Pedro Mire Dores Pulido
Ciência dos materiais
Filmes finos
Revestimentos protectores
Óxidos metálicos
Cobre
Titânio
Microelectrónica - Materiais
title_short Calcium copper titanium oxide thin films for microelectronic applications
title_full Calcium copper titanium oxide thin films for microelectronic applications
title_fullStr Calcium copper titanium oxide thin films for microelectronic applications
title_full_unstemmed Calcium copper titanium oxide thin films for microelectronic applications
title_sort Calcium copper titanium oxide thin films for microelectronic applications
author Valente, João Pedro Mire Dores Pulido
author_facet Valente, João Pedro Mire Dores Pulido
author_role author
dc.contributor.author.fl_str_mv Valente, João Pedro Mire Dores Pulido
dc.subject.por.fl_str_mv Ciência dos materiais
Filmes finos
Revestimentos protectores
Óxidos metálicos
Cobre
Titânio
Microelectrónica - Materiais
topic Ciência dos materiais
Filmes finos
Revestimentos protectores
Óxidos metálicos
Cobre
Titânio
Microelectrónica - Materiais
description Recent research has shown that the perovskite-related body-centred cubic material CaCu3Ti4O12 (CCTO) exhibit extraordinarily giant dielectric constant at room temperature (ε ≈ 104-105). Besides, these high dielectric constants were found to be nearly constant in the temperature range between 100 and 500K [1, 2]; which makes it even more attractive from the technological point of view. These properties are very important for device implementation and make CCTO a promising candidate for microelectronic applications (like decoupling capacitors, random access memories), microwave devices (for applications in mobile phones), antennas (for example, planar micro-strip antenna on CCTO substrate for 3-GHz operation) [3]. In the microelectronics device field, homogeneous and smooth thin films with colossal dielectric constant and with low dielectric loss are desirable. In the literature, only five reports on undoped CCTO films on silicon based substrates prepared by sol-gel method can be found. The majority of these authors did not present the dielectric and microstructural properties of the produced CCTO films. In this work, thin films of CCTO were prepared by sol-gel method by spin coating a nontoxic chemical solution on typical microelectronic substrates, Si (wafer) / SiO2 (300 nm) / TiO2 (20 nm) / Pt (150 nm). Two different precursor solutions were studied and optimized for film production. These two solutions differ mainly on the titanium precursor, although some preparation parameters where changed as well. One of the main objectives of the thesis was to develop nontoxic precursors for CSD method and accordingly, solutions were prepared without methoxyethanol (highly toxic). This constitutes a great improvement considering the good properties obtained for the 300-400 nm thick CCTO films prepared in this work: dielectric permittivity, ε of 500 and dielectric loss, tan of 0.19, for films derived from titanium butoxide precursor solutions (BUT-CCTO) and ε ≈ 620 and dielectric loss 0.18 for those derived from titanium isopropoxide precursor solutions (ISO-CCTO), all values at 1 kHz. In literature, toxic precursor solution of CCTO leads to films with values for dielectric permittivity of 1000-2000 and dielectric loss between 0.5 – 0.04 [52]. Best reports on nontoxic solutions for spin coating method presented dielectric constant (≈ 150-250) and losses around 0.2-0.5 [45]. The physical properties of the films were characterised. The structural and microstructural characterization was conducted via X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). [CALCIUM COPPER TITANIUM OXIDE THIN FILMS FOR MICROELECTRONIC APPLICATIONS] 10 For the electrical characterization the dielectric constant and dielectric losses were measured at room temperature in the range 100 Hz-1 MHz. AFM microstructure and especially potential images, confirmed IBLC model for conduction, since grain and grain boundaries presented different potentials due to their different electrical behaviour. This result was obtained for every sample made with both solutions. Grain size has a considerable influence on the dielectric properties of the thin films. grain films present high dielectric constant and high dielectric loss. Small grain origins lower dielectric constant but also low dielectric loss. In this work and based on IBLC model, it was found that grain and high grain boundaries density will guarantee good permittivity according with [6, 9], although with grain size increase, grain boundaries density decrease. An intermediate stage for grain size must be achieved depending on the solution used. Considering the dielectric loss, it was found to respect mainly to grain boundaries. High density of grain boundaries promotes second phase segregation (TiO2) due to low temperature heat treatments and worst insulator behaviour [18,24]. For one side, high density will lower dielectric loss confirming [6,13], on the other side, second phase segregation will increase it, as reported in [18, 24]. A compromise between the capacity of the semiconductor grains to admit charges and the resistivity of the insulator grain boundaries must be achieved to obtain good quality CCTO thin films. The admission of charges by the grain is controlled by the grain size (heat treatment procedure) meanwhile the current density of the grain boundaries is controlled by second phase segregation (solution procedure) and grain boundaries density (heat treatment procedure). As a final output of this work a new non-toxic precursor solution was developed as an alternative way for preparing CCTO thin films of high dielectric constant for microelectronic applications.
publishDate 2010
dc.date.none.fl_str_mv 2010-01-01T00:00:00Z
2010
2012-03-30T14:26:47Z
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url http://hdl.handle.net/10773/7612
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dc.publisher.none.fl_str_mv Universidade de Aveiro
publisher.none.fl_str_mv Universidade de Aveiro
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reponame_str Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
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repository.name.fl_str_mv Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
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