Part of the work has been performed in the project JEMSiP_3D, which is funded by the Public Authorities in France, Germany, Hungary, The Netherlands, Norway and Sweden, as well as by the ENIAC Joint Undertaking. The authors would like to thank the Dimes Technology Centre staff for processing support.

Atenção: Por favor, consulte todas as fichas de dados de segurança do material (MSDS) relevantes antes de usar. Vários dos produtos químicos utilizados no presente processo de fabricação são altamente tóxicos e cancerígenos. Os nanomateriais podem ter riscos adicionais em comparação com o seu homólogo granel. Utilize todas as práticas de segurança adequadas quando trabalhar com equipamentos, produtos químicos ou nanomateriais, incluindo o uso de controles de engenharia (extractor de fumo) e equipamentos de proteção individual (óculos de segurança, luvas, roupas de sala limpa). 1. Alinhamento marcador de definição para Litografia <ol><li> Comece com grau industrial polido single-sided Si (100) bolachas com qualquer n ou p-type doping. </li><li> Revestir a bolacha com 1,4 uM de fotorresistente positivo. Executar uma 90 seg hexametildissilazano (HMDS) de tratamento a 130 ° C para promover a adesão do foto-resistente, seguido de arrefecimento da bolacha em uma placa fria, spin-coating à velocidade apropriada (3.500 rpm), e um 90 seg coza macio umt 95 ° C. </li><li> O uso da máscara foto-litografia e uma ferramenta de exposição expor as marcas de alinhamento, dose de exposição de 120 mJ / cm 2. </li><li> Realize um único processo de desenvolvimento poça. Executar um 90 seg 115 ° C coza pós-exposição, seguido por 60 sec desenvolvimento utilizando desenvolvedor e asse dura 90 seg a 100 ° C para curar a resistir. </li><li> Usar um microscópio para inspeccionar se as aberturas na parte de resistir são as dimensões correctas. </li><li> Etch 120 nm de Si usando corrosão por plasma de cloro. Esta espessura confere um bom contraste para os sistemas de alinhamento automático da ferramenta de exposição utilizado neste trabalho. Por exemplo, utilizando um plasma indutivo acoplado (ICP): 20/40 sccm de O2 / CF 4, 5 mTorr, 60/500 W cilindro / potência de RF ICP, 10 seg avanço óxido de decapagem, seguido por 80/40 sccm Cl 2 / HBr , 60 mTorr, 20/500 W placa / potência ICP RF, 35 seg Si gravar. </li><li> Use um descascador de plasma de oxigênio para remover o fotorresiste (1 kW, 400 sccm O 2 com endpodetecção int e 2 min overetch). À medida que o revestimento fotoprotector é curado pelo solvente como acetona plasma normal não pode ser utilizado. </li><li> Limpe as bolachas. Primeiro colocá-los durante 10 min em 99% HNO 3, seguido de enxaguamento com água desionizada até que a resistividade da água é de 5 mohms (limpo orgânico). Após este limpa as bolachas durante 10 min em HNO3 65% a 110 ° C, seguido de enxaguamento com água desionizada até que a resistividade da água é de 5 mohms (metal limpo). Use um secador para secar rinser as bolachas. </li></ol> 2. metal inferior e Interlayer dielétrica Deposição <ol><li> Use pulverização por magnetrão a depositar a camada de metal da parte inferior através do teste. Uma pilha de três camadas metálicas tem de ser depositado: 500 nm de Ti, de 50 nm de TiN, Ti e 100 nm. A primeira camada de Ti é reduzir a resistência da pilha, a lata é a camada de suporte para o crescimento efectivo CNT, e o topo Ti é para proteger o TiN contra danos plasma quando condicionamento da camada de SiO2 12 </sup&gt;. Realizar Ti pulverização catódica utilizando um alvo de Ti puro com Ar-plasma a uma temperatura de substrato de 350 ° C. De estanho na forma de pulverização catódica reactiva usar uma combinação de Ar e n 2, de novo, a 350 ° C temperatura do substrato. </li><li> Usando deposição de vapor químico melhorado por plasma (PECVD), depositar um 1 um espessa camada de SiO2. Aqui ortossilicato de tetraetilo (TEOS) é usado como precursor a uma temperatura de cilindro de 350 ° C. <ol><li> Verifique a espessura da camada de SiO 2, utilizando uma ferramenta adequada, por exemplo um reflectómetro ou elipsometria. </li></ol></li><li> Revestir a bolacha com 1,4 uM de fotorresistente positiva, começando com um tratamento de 90 seg HMDS a 130 ° C, seguido de arrefecimento da bolacha em uma placa fria, spin-coating à velocidade apropriada (3.500 rpm), e um 90 seg suave cozer a 95 ° C. </li><li> O uso da máscara foto-litografia e uma ferramenta de exposição, expor o padrão desejado de aberturas, que será mais tarde a gravadas em SiO2 to formar as vias, alinhados com os marcadores de alinhamento, dose de exposição de 140 mJ / cm 2. </li><li> Realizar um único processo de desenvolvimento de uma poça de partida com 90 seg 115 ° C de pós-exposição assar, seguido por 60 seg desenvolvimento utilizando revelador e coze dura 90 segundos a 100 ° C. </li><li> Usar um microscópio para inspeccionar se as aberturas na parte de resistir são as dimensões correctas e se a sobreposição para os marcadores de alinhamento está correcto. </li><li> Plasma gravar as aberturas de contacto no SiO 2. Por exemplo, usar um etcher plasma triodo com C 2 F 6 / CHF 3 36/144 sccm a 180 mTorr e 300 W de potência de RF. Se necessário, efectuar testes de taxa de corrosão sobre uma bolacha de teste, a fim de minimizar mais de gravura a 5% -10% no tempo. Nota: Embora o Ti é resistente ao ataque químico reactivo neste flúor química, a exposição prolongada ao plasma resultará na corrosão física da camada de Ti. Se a camada de estanho é exposta ao plasma isso terá um influenzae negativoce sobre o crescimento da CNT 12. Não use condicionamento úmido, pois isso irá resultar em muito alargamento das aberturas, tornando o top de metalização na parte 4 problemático. </li><li> Retirar a camada de Ti sacrificial por ataque úmido em 0,55% HF durante 60 segundos. Depois de gravar lavar as bolachas com água DI até a resistividade da água é de 5 mohms e usar um secador para secar rinser as bolachas. Nota: Usando um microscópio pode ser verificado se a camada de Ti está gravado, a camada de estanho terá uma cor marrom-ouro, enquanto o Ti é cinza metálico. </li></ol> 3. Catalisador Deposição e Crescimento CNT <ol><li> Evapora-se 5 nM de Co utilizando um evaporador e-beam. Bombear para baixo até pelo menos 2x10 -6 Torr, e aquecer as bolachas a 60 ° C, utilizando lâmpadas sob vácuo antes de depositar para remover qualquer película de água. A foto-resiste usado para definir as aberturas de contato é mantido na bolacha de proporcionar auto-alinhamento do catalisador para as aberturas de contacto no SiO 2. </li><li> Removero Co fora das aberturas de contacto por lift-off. Para a co, verificou-se que o tetra-hidrofurano (THF) dá os melhores resultados de lift-off e crescimento a baixas temperaturas. N-metil-2-pirrolidona (NMP), que foi previamente utilizado para a descolagem Fe após evaporação, foi encontrada a danos Co demasiado tal forma a impedir qualquer crescimento CNT alinhados. Coloque a bolacha durante 15 minutos num banho de ultrassons com THF a 35 ° C. Lavar com água desionizada, durante 5 min e secar utilizando uma pistola de Spinner ou azoto. </li><li> Inspecione o wafer debaixo de um microscópio e verificar se há resíduos de resistir. Se os resíduos permanecem realizar um tratamento mais ultra-som em THF, e, opcionalmente, use um cotonete macio especial para fins de lift-off para limpar manualmente longe resíduos. </li><li> Execute o crescimento CNT usando deposição de vapor químico de baixa pressão (LPCVD). Utilize a seguinte receita: 8 min de pré-recozimento a 350 ° C com 700 sccm de H 2 a 80 mbar, seguido de crescimento CNT por adição de 50 sccm C 2 H 2. A 350 ° C, 60min de crescimento dá cerca de 1 uM de CNT. Se for necessário efectuar um teste de crescimento para ajustar a altura, que devem ser da mesma espessura que a camada de SiO2. Resfriar o reator e limpar usando N2. </li><li> Use um microscópio eletrônico de varredura para verificar a altura do CNT no interior das aberturas sob 45 ° de inclinação, ou através da preparação de uma secção transversal. </li><li> Inspeccionar as amostras utilizando espectroscopia de Raman para determinar a cristalinidade do CNT 18. </li></ol> 4. Topside Metalização <ol><li> Use pulverização catódica para depositar o topo metal. Como Ti é um bom metal para o contactar CNT 19, primeiro por pulverização catódica 100 nm de Ti, seguido por 2 mm de Al (1% Si) sem quebrar o vácuo. </li><li> Revestir a bolacha com 3,1 uM de fotorresistente positiva com viscosidade mais elevada, a partir de um tratamento de 90 seg HMDS a 130 ° C, seguido de arrefecimento da bolacha em uma placa fria, spin-coating a 3.000 rpm, e um cozimento macio 90 seg a 95° C. </li><li> O uso da máscara foto-litografia e uma ferramenta de exposição expor o padrão de metal superior alinhada com as marcas de alinhamento, dose de exposição de 420 mJ / cm 2, o foco de -1. </li><li> Realize um único processo de desenvolvimento poça. Isso começa com um 90 seg 115 ° C pós-exposição de bolos, seguido por 60 sec desenvolvimento utilizando desenvolvedor e asse dura 90 seg a 100 ° C. </li><li> Usar um microscópio para inspeccionar se as linhas no resistir são das dimensões correctas e se a sobreposição para os marcadores é correcta. </li><li> Etch a pilha de Ti / Al utilizar gravação por plasma de cloro. Por exemplo, utilizando um plasma indutivo: 30/40 sccm Cl 2 / HBr, 5 mTorr, 40/500 poder W Platen / ICP RF com detecção de endpoint e 80% overetch usando 15/30 sccm Cl 2 / HBr. </li><li> Use um descascador de plasma de oxigênio para remover o fotorresiste (1 kW, 400 sccm O 2 com a detecção de endpoint e 2 min overetch). Se a cobertura não é completa de metal (isto é, existem orifícios em torno daCNT) usar um solvente orgânico (por exemplo, NMP) para remover o material fotosensitivo, a fim de evitar danos no plasma para o CNT. </li><li> Limpe as bolachas. Colocá-los durante 10 min em 99% HNO 3, seguido de enxaguamento com água desionizada até que a resistividade da água é de 5 mohms (limpo orgânico). Use um secador para secar rinser as bolachas. </li></ol> 5. Medições <ol><li> Use um microscópio eletrônico de varredura de acordo com as instruções do fabricante para verificar o top metalização das bolachas. Nota:. Como as amostras são electricamente condutora ter para ser usado sem passos de tratamento adicionais, se necessário, a bolacha pode ser clivado mecanicamente, a fim de verificar o CNT completa através de usar uma inclinação amostra de 90 °, resultando em imagens, como mostrado na Figura 3 e as amostras podem ser directamente montado no SEM. Geralmente, tensões de aceleração de 15 kV ou 20 pode ser utilizado, mas, se a camada de SiO2 está a carregar-se demasiado este pode ser reduzido tO 5 kV. </li><li> Efectuar as medições de 4 pontos sonda IV, utilizando uma estação sonda, em combinação com um parâmetro analisador semicondutor, tal como descrito na Figura 1 e na Vollebregt et ai. 16. Nota: Normalmente uma varredura tensão de -0,5 a 0,5 V é suficiente, como a queda de potencial através de uma interligação ideal é pequena. Ao usar uma configuração de sonda de 4 pontos a resistência de contato das agulhas da sonda e as resistências de fio da configuração são omitidos. </li></ol>

<ol>
	<li>Sun, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Process+technologies+for+advanced+metallization+and+interconnect+systems.">Process technologies for advanced metallization and interconnect systems.</a> Technical digest of the IEEE International Electron Devices Meeting. , 765-768 (1997).</li><li>Robertson, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth+of+nanotubes+for+electronics.">Growth of nanotubes for electronics.</a> Mater. Today. 10 (1-2), 36-43 (2007).</li><li>Wei, B. Q., Vajtai, R., Ajayan, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reliability+and+current+carrying+capacity+of+carbon+nanotubes.">Reliability and current carrying capacity of carbon nanotubes.</a> Appl. Phys. Lett. 79 (8), 1172-1174 (2001).</li><li>Rossnagel, S. M., Wisnieff, R., Edelstein, D., Kuan, T. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interconnect+issues+post+45nm.">Interconnect issues post 45nm.</a> Technical digest of the IEEE International Electron Devices Meeting. , 89-91 (2005).</li><li>Pop, E., Mann, D., Wang, Q., Goodson, K., Dai, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermal+Conductance+of+an+Individual+Single-Wall+Carbon+Nanotube+above+Room+Temperature.">Thermal Conductance of an Individual Single-Wall Carbon Nanotube above Room Temperature.</a> Nano Lett. 6 (1), 96-100 (2006).</li><li>Chiodarelli, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+the+electrical+resistivity+and+contact+resistance+of+vertical+carbon+nanotube+bundles+for+application+as+interconnects.">Measuring the electrical resistivity and contact resistance of vertical carbon nanotube bundles for application as interconnects.</a> Nanotechnology. 22 (8), 085302 (2011).</li><li>Choi, Y. -. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integration+and+Electrical+Properties+of+Carbon+Nanotube+Array+for+Interconnect+Applications.">Integration and Electrical Properties of Carbon Nanotube Array for Interconnect Applications.</a> Proceedings of the Sixth IEEE Conference on Nanotechnology. , 262-265 (2006).</li><li>Dijon, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultra-high+density+Carbon+Nanotubes+on+Al-Cu+for+advanced+Vias.">Ultra-high density Carbon Nanotubes on Al-Cu for advanced Vias.</a> Technical digest of the IEEE International Electron Devices Meeting. , 33-34 (2010).</li><li>Kreupl, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+nanotubes+in+interconnect+applications.">Carbon nanotubes in interconnect applications.</a> Microelectron. Eng. 64 (1-4), 399-408 (2002).</li><li>Vereecke, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+carbon+nanotube+based+vertical+interconnects.">Characterization of carbon nanotube based vertical interconnects.</a> Extended Abstracts of the 2012 International Conference on Solid State Devices and Materials. , 648-649 (2012).</li><li>Vollebregt, S., Ishihara, R., Derakhshandeh, J., vander Cingel, J., Schellevis, H., Beenakker, C. I. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrating+low+temperature+aligned+carbon+nanotubes+as+vertical+interconnects+in+Si+technology.">Integrating low temperature aligned carbon nanotubes as vertical interconnects in Si technology.</a> Proceedings of the 11th IEEE Conference on Nanotechnology. , 985-990 (2011).</li><li>Yokoyama, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+Properties+of+Carbon+Nanotubes+Grown+at+a+Low+Temperature+for+Use+as+Interconnects.">Electrical Properties of Carbon Nanotubes Grown at a Low Temperature for Use as Interconnects.</a> Jpn J. App. Phys. 47 (4), 1985-1990 (2008).</li><li>Van der Veen, M. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+Improvement+of+CNT+Contacts+with+Cu+Damascene+Top+Metallization.">Electrical Improvement of CNT Contacts with Cu Damascene Top Metallization.</a> Proceedings of the IEEE International Interconnect Technology Conference. , 193-195 (2013).</li><li>Istratov, A. A., Hieslmair, H., Weber, E. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Iron+contamination+in+silicon+technology.">Iron contamination in silicon technology.</a> Appl. Phys. A. 70, 489-534 (2000).</li><li>Vollebregt, S., Tichelaar, F. D., Schellevis, H., Beenakker, C. I. M., Ishihara, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+nanotube+vertical+interconnects+fabricated+at+temperatures+as+low+as+350+&#176;C.">Carbon nanotube vertical interconnects fabricated at temperatures as low as 350 &#176;C.</a> 71, 249-256 (2014).</li><li>Kikkawa, T., Inoue, K., Imai, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cobalt+silicide+technology.">Cobalt silicide technology.</a> Silicide Technology for Integrated Circuits. , 77-94 (2004).</li><li>Vollebregt, S., Ishihara, R., Tichelaar, F. D., Hou, Y., Beenakker, C. I. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+the+growth+temperature+on+the+first+and+second-order+Raman+band+ratios+and+widths+of+carbon+nanotubes+and+fibers.">Influence of the growth temperature on the first and second-order Raman band ratios and widths of carbon nanotubes and fibers.</a> Carbon. 50 (10), 3542-3554 (2012).</li><li>Lim, S. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contact+resistance+between+metal+and+carbon+nanotube+interconnects:+Effect+of+work+function+and+wettability.">Contact resistance between metal and carbon nanotube interconnects: Effect of work function and wettability.</a> Appl. Phys. Lett. 95 (26), 264103 (2009).</li><li>Awano, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+nanotube+via+interconnect+technologies:+size-classified+catalyst+nanoparticles+and+low-resistance+ohmic+contact+formation.">Carbon nanotube via interconnect technologies: size-classified catalyst nanoparticles and low-resistance ohmic contact formation.</a> Phys. Status Solidi (a). 203 (14), 3611-3616 (2006).</li><li>Van der Veen, M. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+characterization+of+CNT+contacts+with+Cu+Damascene+top+contact.">Electrical characterization of CNT contacts with Cu Damascene top contact.</a> Microelectron. Eng. 106, 106-111 (2012).</li><li>Horibe, M., Nihei, M., Kondo, D., Kawabata, A., Awano, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+Polishing+Technique+for+Carbon+Nanotube+Interconnects+in+ULSIs.">Mechanical Polishing Technique for Carbon Nanotube Interconnects in ULSIs.</a> Jpn J. App. Phys. 43 (9A), 6499-6502 (2004).</li><li>Vollebregt, S., Chiaramonti, A. N., Ishihara, R., Schellevis, H., Beenakker, C. I. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contact+resistance+of+low-temperature+carbon+nanotube+vertical+interconnects.">Contact resistance of low-temperature carbon nanotube vertical interconnects.</a> Proceedings of the 12th IEEE Conference on Nanotechnology. , 424-428 (2012).</li><li>Fiorentino, G., Vollebregt, S., Tichelaar, F. D., Ishihara, R., Sarro, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+the+atomic+layer+deposition+precursors+diffusion+on+solid-state+carbon+nanotube+based+supercapacitors+performances.">Impact of the atomic layer deposition precursors diffusion on solid-state carbon nanotube based supercapacitors performances.</a> Nanotechnology. 26 (6), 064002 (2015).</li></ol>

The authors have nothing to disclose.

A Figura 1 mostra uma vista geral esquemática da estrutura fabricada neste trabalho, e que foi utilizado para as medições de sonda de 4 pontos. À medida que o potencial é medido por meio de sondas que transportam nenhuma corrente, a queda de potencial exacto (VH-VL) através do feixe CNT central e os contactos para o metal pode ser medido. Maior diâmetro feixes CNT são usadas para contactar a camada de estanho inferior das almofadas de contacto, a fim de reduzir a resistência total pa...

Cobre e tungstênio, os metais que são actualmente utilizados para as interconexões em tecnologia state-of-the-art de muito grande escala de integração (VLSI), estão se aproximando de seus limites físicos em termos de confiabilidade e condutividade elétrica 1. Enquanto transistores down-dimensionamento geralmente melhora seu desempenho, ele realmente aumenta a resistência ea densidade de corrente das interconexões. Isto resultou em interconexões dominando o desempenho do circuito integrado (IC) em termos de atraso e consumo de energia 2. Os nanotubos de carbono (CNT) têm sido sugeridos como alternativa para o Cu e W metalização, especialmente para interconexões verticais (vias) como facilmente pode CNT sido cultivadas verticais 3. CNT tenha sido demonstrado que possuem uma excelente fiabilidade eléctrica, permitindo um até 1000 vezes mais elevada do que a densidade de corrente de Cu 4. Além disso, a CNT não sofrem de superfície e contorno de grão de dispersão, que está a aumentar o resistivity de Cu em escala nanométrica 5. Finalmente, CNT foram mostrados para ser excelentes condutores térmicos 6, que podem ajudar no tratamento térmico em chips VLSI. Para a integração bem sucedida da tecnologia CNT em VLSI, é importante que os processos de crescimento para o CNT é tornado compatível com o fabrico de semicondutores. Isto exige que o baixo crescimento da temperatura do CNT (&lt;400 ° C), utilizando materiais e equipamentos que são considerados compatíveis e escalável para a fabricação em grande escala. Embora muitos exemplos de vias de teste CNT tem sido demonstrado na literatura 7,8,9,10,11,12,13,14, a maioria destes Fe utilizar como catalisador o que é considerado como um contaminante no fabrico de IC 15. Além disso, a temperatura de crescimento utilizados em muitos destes trabalhos é muito maior do que o limite superior de 400 ° C. Preferencialmente CNT deve ainda ser cultivadas abaixo de 350 ° C, a fim de permitir a integração com baixo-k dieléctricos modernos ou flexívelsubstratos. Aqui é apresentado um método para o cultivo de escalável CNT a temperaturas tão baixas como 350 ° C, utilizando como catalisador Co 16. Este método é de interesse para a fabricação de diferentes estruturas eléctricas que consistem em alinhados verticalmente CNT em circuitos integrados, variando de interconexão e eletrodos para capacitores super e dispositivos de emissão de campo. O catalisador de metal de Co é muitas vezes usado no fabrico de circuitos integrados para a fabricação de silicieto de 17, enquanto o estanho é um material de barreira usado muitas vezes 7. Além disso, nós demonstramos um processo para a fabricação de vias de teste CNT enquanto apenas utilizando técnicas de fabricação de semicondutores padrão. Com isso, vias de teste CNT são fabricados, inspecionado por microscopia eletrônica de varredura (MEV) e espectroscopia Raman, e eletricamente caracterizada.

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			<td height="21" style="height:21px;width:307px;">Materials</td>
			<td style="width:188px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td style="width:291px;">Comments/Description</td>
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			<td height="21" style="height:21px;width:307px;">Si (100) wafer 4&#34;</td>
			<td style="width:188px;">International Wafer Service</td>
			<td style="width:119px;"></td>
			<td>Resisitivity: 2-5 m&#937;-cm, thickness: 525 &#181;m&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Ti-sputtertarget (99.995 % purity)</td>
			<td style="width:188px;">Praxair</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Al (1% Si)-sputtertarget (99.999 % purity)</td>
			<td style="width:188px;">Praxair</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Co (99.95 % purity)</td>
			<td style="width:188px;">Kurt J. Lesker</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Chemicals</td>
			<td style="width:188px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">SPR3012 positive photoresist</td>
			<td style="width:188px;">Dow Electronic Materials</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">MF-322 developer</td>
			<td style="width:188px;">Dow Electronic Materials</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">HNO3 (99.9 %)</td>
			<td style="width:188px;">KMG Ultra Pure Chemicals</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">HNO3 (69.5%)</td>
			<td style="width:188px;">KMG Ultra Pure Chemicals</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">HF 0.55%</td>
			<td style="width:188px;">Honeywell</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Tetrahydrofuran</td>
			<td style="width:188px;">JT Baker</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Acetone</td>
			<td style="width:188px;">Sigma-Aldrich</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">ECI3027 positive photoresist</td>
			<td style="width:188px;">AZ</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Tetraethyl orthosilicate (TEOS)</td>
			<td style="width:188px;">Praxair</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Gasses</td>
			<td style="width:188px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">N2 (99.9990%)</td>
			<td style="width:188px;">Praxair</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">O2 (99.9999%)</td>
			<td style="width:188px;">Praxair</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">CF4 (99.9970%)</td>
			<td style="width:188px;">Praxair</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">CL2 (99.9900%)</td>
			<td style="width:188px;">Praxair</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">HBr (99.9950%)</td>
			<td style="width:188px;">Praxair</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Ar (99.9990%)</td>
			<td style="width:188px;">Praxair</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">C2F6 (99.9990%)</td>
			<td style="width:188px;">Praxair</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">CHF3 (99.9950%)</td>
			<td style="width:188px;">Praxair</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">H2 (99.9950%)</td>
			<td style="width:188px;">Praxair</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">C2H2 (99.6000%)</td>
			<td style="width:188px;">Praxair</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Equipment</td>
			<td style="width:188px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">EVG 120 coater/developer</td>
			<td style="width:188px;">EVG</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">ASML PAS5500/80 waferstepper</td>
			<td style="width:188px;">ASML</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">SPTS &#937;mega 201 plasma etcher</td>
			<td style="width:188px;">SPTS</td>
			<td style="width:119px;"></td>
			<td>Used for Si and metal etching</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">SPTS &#931;igma sputter coater</td>
			<td style="width:188px;">SPTS</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Novellus Concept One PECVD</td>
			<td style="width:188px;">LAM</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Drytek 384T plasma etcher</td>
			<td style="width:188px;">LAM</td>
			<td style="width:119px;"></td>
			<td>Used for oxide etching</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">CHA Solution e-beam evaporator</td>
			<td style="width:188px;">CHA</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">AIXTRON BlackMagic Pro CVD tool</td>
			<td style="width:188px;">AIXTRON</td>
			<td style="width:119px;"></td>
			<td>Carbon nanotube growth</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Philips XL50 scanning electron microscope</td>
			<td style="width:188px;">FEI</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Tepla 300</td>
			<td style="width:188px;">PVA TePla</td>
			<td style="width:119px;"></td>
			<td>Resist plasma stripper</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Avenger rinser dryer</td>
			<td style="width:188px;">Microporcess Technologies</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Leitz MPV-SP reflecometer</td>
			<td style="width:188px;">Leitz</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Renishaw inVia Raman spectroscope</td>
			<td style="width:188px;">Renishaw</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Agilent 4156C parameter spectrum analyzer</td>
			<td style="width:188px;">Agilent</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Cascade Microtech probe station</td>
			<td style="width:188px;">Cascade Microtech</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

fabrication of low temperature carbon nanotube vertical interconnects compatible with semiconductor technology

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive thin-films. Due to the low growth temperature, the process allows integration with modern low-&#954; dielectrics and some flexible substrates. The process is compatible with standard semiconductor fabrication, and a method for the fabrication of electrical 4-point probe test structures for vertical interconnect test structures is presented. Using scanning electron microscopy the morphology of the CNT bundles is investigated, which demonstrates vertical alignment of the CNT and can be used to tune the CNT growth time. With Raman spectroscopy the crystallinity of the CNT is investigated. It was found that the CNT have many defects, due to the low growth temperature. The electrical current-voltage measurements of the test vertical interconnects displays a linear response, indicating good ohmic contact was achieved between the CNT bundle and the top and bottom metal electrodes. The obtained resistivities of the CNT bundle are among the average values in the literature, while a record-low CNT growth temperature was used.

O design da estrutura de medição utilizado neste trabalho podem ser encontrados na Figura 1. Empregando uma tal estrutura a medição da resistência feixe CNT e as resistências de contacto de metal-CNT pode ser determinada com precisão, como sonda e resistências de arame são contornadas. A resistência do pacote é uma medida para a qualidade e densidade do pacote CNT. A fim de determinar os feixes de resistência de contacto de comprimentos diferentes devem ser medidos. <p c...

Watch this Scientific Journal Video about Fabrication of Low Temperature Carbon Nanotube Vertical Interconnects Compatible with Semiconductor Technology at JoVE.com

Fabrication of Low Temperature Carbon Nanotube Vertical Interconnects Compatible with Semiconductor Technology

A method for the growth of low temperature vertically-aligned carbon nanotubes, and the subsequent fabrication of vertical interconnect electrical test structures using semiconductor fabrication is presented.

Fabricação de Baixa Temperatura de Nanotubos de Carbono Vertical Interconexões Compatível com Semiconductor Tecnologia

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive ...

fabrication-low-temperature-carbon-nanotube-vertical-interconnects

Research

JoVE Journal

Engineering

7.6K visualizações.  Delft University of Technology. A method for the growth of low temperature vertically-aligned carbon nanotubes, and the subsequent fabrication of vertical interconnect electrical test structures using semiconductor fabrication is presented.

Vídeo: Fabrication of Low Temperature Carbon Nanotube Vertical Interconnects Compatible with Semiconductor Technology

Fabrication, Densification, and Replica Molding of 3D Carbon Nanotube Microstructures

The introduction of new materials and processes to microfabrication has, in large part, enabled many important advances in microsystems, lab-on-a-chip devices, and their applications. In particular, capabilities for cost-effective fabrication of polymer microstructures were transformed by the advent of soft lithography and other micromolding techniques 1, 2, and this led a revolution in applications of microfabrication to biomedical engineering and biology. Nevertheless, it remains challenging to fabricate microstructures with well-defined nanoscale surface textures, and to fabricate arbitrary 3D shapes at the micro-scale. Robustness of master molds and maintenance of shape integrity is especially important to achieve high fidelity replication of complex structures and preserving their nanoscale surface texture. The combination of hierarchical textures, and heterogeneous shapes, is a profound challenge to existing microfabrication methods that largely rely upon top-down etching using fixed mask templates. On the other hand, the bottom-up synthesis of nanostructures such as nanotubes and nanowires can offer new capabilities to microfabrication, in particular by taking advantage of the collective self-organization of nanostructures, and local control of their growth behavior with respect to microfabricated patterns. 
Our goal is to introduce vertically aligned carbon nanotubes (CNTs), which we refer to as CNT "forests", as a new microfabrication material. We present details of a suite of related methods recently developed by our group: fabrication of CNT forest microstructures by thermal CVD from lithographically patterned catalyst thin films; self-directed elastocapillary densification of CNT microstructures; and replica molding of polymer microstructures using CNT composite master molds. In particular, our work shows that self-directed capillary densification ("capillary forming"), which is performed by condensation of a solvent onto the substrate with CNT microstructures, significantly increases the packing density of CNTs. This process enables directed transformation of vertical CNT microstructures into straight, inclined, and twisted shapes, which have robust mechanical properties exceeding those of typical microfabrication polymers. This in turn enables formation of nanocomposite CNT master molds by capillary-driven infiltration of polymers. The replica structures exhibit the anisotropic nanoscale texture of the aligned CNTs, and can have walls with sub-micron thickness and aspect ratios exceeding 50:1. Integration of CNT microstructures in fabrication offers further opportunity to exploit the electrical and thermal properties of CNTs, and diverse capabilities for chemical and biochemical functionalization 3.

We present methods for fabrication of patterned microstructures of vertically aligned carbon nanotubes (CNTs), and their use as master molds for production of polymer microstructures with organized nanoscale surface texture. The CNT forests are densified by condensation of solvent onto the substrate, which significantly increases their packing density and enables self-directed formation of 3D shapes.

Fabricação, Densificação e Replica Moldagem de Microestruturas de Nanotubos de Carbono 3D

The introduction of new materials and processes to microfabrication has, in large part, enabled many important advances in microsystems, lab-on-a-chip ...

Engenharia

Dry Oxidation and Vacuum Annealing Treatments for Tuning the Wetting Properties of Carbon Nanotube Arrays

In this article, we describe a simple method to reversibly tune the wetting properties of vertically aligned carbon nanotube (CNT) arrays. Here, CNT arrays are defined as densely packed multi-walled carbon nanotubes oriented perpendicular to the growth substrate as a result of a growth process by the standard thermal chemical vapor deposition (CVD) technique.1,2 These CNT arrays are then exposed to vacuum annealing treatment to make them more hydrophobic or to dry oxidation treatment to render them more hydrophilic. The hydrophobic CNT arrays can be turned hydrophilic by exposing them to dry oxidation treatment, while the hydrophilic CNT arrays can be turned hydrophobic by exposing them to vacuum annealing treatment. Using a combination of both treatments, CNT arrays can be repeatedly switched between hydrophilic and hydrophobic.2 Therefore, such combination show a very high potential in many industrial and consumer applications, including drug delivery system and high power density supercapacitors.3-5
The key to vary the wettability of CNT arrays is to control the surface concentration of oxygen adsorbates. Basically oxygen adsorbates can be introduced by exposing the CNT arrays to any oxidation treatment. Here we use dry oxidation treatments, such as oxygen plasma and UV/ozone, to functionalize the surface of CNT with oxygenated functional groups. These oxygenated functional groups allow hydrogen bond between the surface of CNT and water molecules to form, rendering the CNT hydrophilic. To turn them hydrophobic, adsorbed oxygen must be removed from the surface of CNT. Here we employ vacuum annealing treatment to induce oxygen desorption process. CNT arrays with extremely low surface concentration of oxygen adsorbates exhibit a superhydrophobic behavior.

This article describes a simple method to fabricate vertically aligned carbon nanotube arrays by CVD and to subsequently tune their wetting properties by exposing them to vacuum annealing or dry oxidation treatment.

Oxidação seca e vácuo Annealing Tratamentos para Ajustando as propriedades de umectação Matrizes Nanotubos de Carbono

In this article, we describe a simple method to reversibly  tune the wetting properties of vertically aligned carbon nanotube (CNT) arrays.  Here, CNT ...

Synthesis and Functionalization of Nitrogen-doped Carbon Nanotube Cups with Gold Nanoparticles as Cork Stoppers

Nitrogen-doped carbon nanotubes consist of many cup-shaped graphitic compartments termed as nitrogen-doped carbon nanotube cups (NCNCs). These as-synthesized graphitic nanocups from chemical vapor deposition (CVD) method were stacked in a head-to-tail fashion held only through noncovalent interactions. Individual NCNCs can be isolated out of their stacking structure through a series of chemical and physical separation processes. First, as-synthesized NCNCs were oxidized in a mixture of strong acids to introduce oxygen-containing defects on the graphitic walls. The oxidized NCNCs were then processed using high-intensity probe-tip sonication which effectively separated the stacked NCNCs into individual graphitic nanocups. Owing to their abundant oxygen and nitrogen surface functionalities, the resulted individual NCNCs are highly hydrophilic and can be effectively functionalized with gold nanoparticles (GNPs), which preferentially fit in the opening of the cups as cork stoppers. These graphitic nanocups corked with GNPs may find promising applications as nanoscale containers and drug carriers.

We discussed the synthesis of individual graphitic nanocups using a series of techniques including chemical vapor deposition, acid oxidation and probe-tip sonication. By citrate reduction of HAuCl4, the graphitic nanocups were effectively corked with gold nanoparticles due to the chemically reactive edges of the cups.

Síntese e funcionalização de nitrogênio dopado Copas de Nanotubos de Carbono com nanopartículas de ouro como Rolhas

Nitrogen-doped carbon  nanotubes consist of many cup-shaped graphitic compartments termed as  nitrogen-doped carbon nanotube cups (NCNCs).  These ...

Writing and Low-Temperature Characterization of Oxide Nanostructures

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions. Oxide interfaces exhibit a wide range of properties that can be controlled include conduction, piezoelectric behavior, ferromagnetism, superconductivity and nonlinear optical properties. Recently, methods for controlling these properties at extreme nanoscale dimensions have been discovered and developed. Here are described explicit step-by-step procedures for creating LaAlO3/SrTiO3 nanostructures using a reversible conductive atomic force microscopy technique. The processing steps for creating electrical contacts to the LaAlO3/SrTiO3 interface are first described. Conductive nanostructures are created by applying voltages to a conductive atomic force microscope tip and locally switching the LaAlO3/SrTiO3 interface to a conductive state. A versatile nanolithography toolkit has been developed expressly for the purpose of controlling the atomic force microscope (AFM) tip path and voltage. Then, these nanostructures are placed in a cryostat and transport measurements are performed. The procedures described here should be useful to others wishing to conduct research in oxide nanoelectronics.

Oxide nanostructures provide new opportunities for science and technology. The interfacial conductivity between LaAlO3 and SrTiO3 can be controlled with near-atomic precision using a conductive atomic force microscopy technique. The protocol for creating and measuring conductive nanostructures at LaAlO3/SrTiO3 interfaces is demonstrated.

Escrita e Caracterização baixa temperatura de óxido de Nanoestruturas

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions.  Oxide ...

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures

Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor performance, which suggest a new direction for the development of next-generation ultrathin and flexible photonic and electronic devices. Enhanced luminescence quantum efficiency has been widely observed in these atomically thin 2D crystals. However, dimension effects beyond quantum confinement thicknesses or even at the micrometer scale are not expected and have rarely been observed. In this study, molybdenum diselenide (MoSe2) layer crystals with a thickness range of 6-2,700 nm were fabricated as two- or four-terminal devices. Ohmic contact formation was successfully achieved by the focused-ion beam (FIB) deposition method using platinum (Pt) as a contact metal. Layer crystals with various thicknesses were prepared through simple mechanical exfoliation by using dicing tape. Current-voltage curve measurements were performed to determine the conductivity value of the layer nanocrystals. In addition, high-resolution transmission electron microscopy, selected-area electron diffractometry, and energy-dispersive X-ray spectroscopy were used to characterize the interface of the metal&#8211;semiconductor contact of the FIB-fabricated MoSe2 devices. After applying the approaches, the substantial thickness-dependent electrical conductivity in a wide thickness range for the MoSe2-layer semiconductor was observed. The conductivity increased by over two orders of magnitude from 4.6 to 1,500 &#937;&#8722;1 cm&#8722;1, with a decrease in the thickness from 2,700 to 6 nm. In addition, the temperature-dependent conductivity indicated that the thin MoSe2 multilayers exhibited considerably weak semiconducting behavior with activation energies of 3.5-8.5 meV, which are considerably smaller than those (36-38 meV) of the bulk. Probable surface-dominant transport properties and the presence of a high surface electron concentration in MoSe2 are proposed. Similar results can be obtained for other layer semiconductor materials such as MoS2 and WS2.

We describe the approaches for the device fabrication and electrical characterization of molybdenum diselenide (MoSe2) layer semiconductor nanostructures with different thicknesses. In addition, the fabrication of ohmic contacts for MoSe2-layer nanocrystals by the focused-ion beam deposition method using platinum (Pt) as a contact metal is described.

Ohmic Contato Fabrication usando uma técnica Focused-ion Beam e caracterização elétrica para camada semicondutora Nanoestruturas

Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor ...

Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film synthesis) for the purpose of exploratory materials research. Certain materials pose a challenge wherein the traditional bulk Hall bar device fabrication method is insufficient to produce a measureable device for sample transport measurement, principally because the single crystal size is too small to attach wire leads to the sample in a Hall bar configuration. This can be, for example, because the first batch of a new material synthesized yields very small single crystals or because flakes of samples of one to very few monolayers are desired. In order to enable rapid characterization of materials that may be carried out in parallel with improvements to their growth methodology, a method of device fabrication for very small samples has been devised to permit the characterization of novel materials as soon as a preliminary batch has been produced. A slight variation of this methodology is applicable to producing devices using exfoliated samples of two-dimensional materials such as graphene, hexagonal boron nitride (hBN), and transition metal dichalcogenides (TMDs), as well as multilayer heterostructures of such materials. Here we present detailed protocols for the experimental device fabrication of fragments and flakes of novel materials with micron-sized dimensions onto substrate and subsequent measurement in a commercial superconducting magnet, dry helium close-cycle cryostat magnetotransport system at temperatures down to 0.300 K and magnetic fields up to 12 T.

We describe the methodology of mechanical exfoliation and deposition of flakes of novel materials with micron-sized dimensions onto substrate, fabrication of experimental device structures for transport experimentation, and the magnetotransport measurement in a dry helium close-cycle cryostat at temperatures down to 0.300 K and magnetic fields up to 12 T.

Métodos experimentais avançados para baixa temperatura Magnetotransporte Medição de novos materiais

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film ...

Precision Milling of Carbon Nanotube Forests Using Low Pressure Scanning Electron Microscopy

A nanoscale fabrication technique appropriate for milling carbon nanotube (CNT) forests is described. The technique utilizes an environmental scanning electron microscope (ESEM) operating with a low pressure water vapor ambient. In this technique, a portion of the electron beam interacts with the water vapor in the vicinity of the CNT sample, dissociating the water molecules into hydroxyl radicals and other species by radiolysis. The remainder of the electron beam interacts with the CNT forest sample, making it susceptible to oxidation from the chemical products of radiolysis. This technique may be used to trim a selected region of an individual CNT, or it may be used to remove hundreds of cubic microns of material by adjusting ESEM parameters. The machining resolution is similar to the imaging resolution of the ESEM itself. The technique produces only small quantities of carbon residue along the boundaries of the cutting zone, with minimal effect on the native structural morphology of the CNT forest.

Low pressure scanning electron microscopy in a water vapor ambient is used to machine nanoscale to microscale features in carbon nanotube forests.

Precision Fresagem de Nanotubos de Carbono Florestas Usando Baixa Pressão Scanning Electron Microscopy

A nanoscale fabrication technique appropriate for milling carbon nanotube (CNT) forests is described. The technique utilizes an environmental scanning ...

High Temperature Fabrication of Nanostructured Yttria-Stabilized-Zirconia (YSZ) Scaffolds by In Situ Carbon Templating Xerogels

We demonstrate a method for the high temperature fabrication of porous, nanostructured yttria-stabilized-zirconia (YSZ, 8 mol% yttria - 92 mol% zirconia) scaffolds with tunable specific surface areas up to 80 m2&#183;g-1. An aqueous solution of a zirconium salt, yttrium salt, and glucose is mixed with propylene oxide (PO) to form a gel. The gel is dried under ambient conditions to form a xerogel. The xerogel is pressed into pellets and then sintered in an argon atmosphere. During sintering, a YSZ ceramic phase forms and the organic components decompose, leaving behind amorphous carbon. The carbon formed in situ serves as a hard template, preserving a high surface area YSZ nanomorphology at sintering temperature. The carbon is subsequently removed by oxidation in air at low temperature, resulting in a porous, nanostructured YSZ scaffold. The concentration of the carbon template and the final scaffold surface area can be systematically tuned by varying the glucose concentration in the gel synthesis. The carbon template concentration was quantified using thermogravimetric analysis (TGA), the surface area and pore size distribution was determined by physical adsorption measurements, and the morphology was characterized using scanning electron microscopy (SEM). Phase purity and crystallite size was determined using X-ray diffraction (XRD). This fabrication approach provides a novel, flexible platform for realizing unprecedented scaffold surface areas and nanomorphologies for ceramic-based electrochemical energy conversion applications, e.g. solid oxide fuel cell (SOFC) electrodes.

High Temperature Fabrication of Nanostructured Yttria-Stabilized-Zirconia YSZ Scaffolds by In Situ Carbon Templating Xerogels

A protocol for fabricating porous, nanostructured yttria-stabilized-zirconia (YSZ) scaffolds at temperatures between 1,000 &#176;C and 1,400 &#176;C is presented.

Fabricação de alta temperatura de nanoestruturado ria-Stabilized Zirconia-Scaffolds (ZEI) pela<em&gt; In Situ</em&gt; Carbono Templating xerogéis

We demonstrate a method for the high temperature fabrication of porous, nanostructured yttria-stabilized-zirconia (YSZ, 8 mol% yttria - 92 mol% zirconia) ...

Fabrication of 3D Carbon Microelectromechanical Systems (C-MEMS)

A wide range of carbon sources are available in nature, with a variety of micro-/nanostructure configurations. Here, a novel technique to fabricate long and hollow glassy carbon microfibers derived from human hairs is introduced. The long and hollow carbon structures were made by the pyrolysis of human hair at 900 &#176;C in a N2 atmosphere. The morphology and chemical composition of natural and pyrolyzed human hairs were investigated using scanning electron microscopy (SEM) and electron-dispersive X-ray spectroscopy (EDX), respectively, to estimate the physical and chemical changes due to pyrolysis. Raman spectroscopy was used to confirm the glassy nature of the carbon microstructures. Pyrolyzed hair carbon was introduced to modify screen-printed carbon electrodes ; the modified electrodes were then applied to the electrochemical sensing of dopamine and ascorbic acid. Sensing performance of the modified sensors was improved as compared to the unmodified sensors. To obtain the desired carbon structure design, carbon micro-/nanoelectromechanical system (C-MEMS/C-NEMS) technology was developed. The most common C-MEMS/C-NEMS fabrication process consists of two steps: (i) the patterning of a carbon-rich base material, such as a photosensitive polymer, using photolithography; and (ii) carbonization through the pyrolysis of the patterned polymer in an oxygen-free environment. The C-MEMS/NEMS process has been widely used to develop microelectronic devices for various applications, including in micro-batteries, supercapacitors, glucose sensors, gas sensors, fuel cells, and triboelectric nanogenerators. Here, recent developments of a high-aspect ratio solid and hollow carbon microstructures with SU8 photoresists are discussed. The structural shrinkage during pyrolysis was investigated using confocal microscopy and SEM. Raman spectroscopy was used to confirm the crystallinity of the structure, and the atomic percentage of the elements present in the material before and after pyrolysis was measured using EDX.

Fabrication of 3D Carbon Microelectromechanical Systems C-MEMS

Long and hollow glassy carbon microfibers were fabricated based on the pyrolysis of a natural product, human hair. The two fabrication steps of carbon microelectromechanical and carbon nanoelectromechanical systems, or C-MEMS and C-NEMS, are: (i) photolithography of a carbon-rich polymer precursor and (ii) pyrolysis of the patterned polymer precursor.

Fabricação de sistemas 3D Microelectromecânicos de Carbono (C-MEMS)

A wide range of carbon sources are available in nature, with a variety of micro-/nanostructure configurations. Here, a novel technique to fabricate long ...

Flow-assisted Dielectrophoresis: A Low Cost Method for the Fabrication of High Performance Solution-processable Nanowire Devices

Flow-assisted dielectrophoresis (DEP) is an efficient self-assembly method for the controllable and reproducible positioning, alignment, and selection of nanowires. DEP is used for nanowire analysis, characterization, and for solution-based fabrication of semiconducting devices. The method works by applying an alternating electric field between metallic electrodes. The nanowire formulation is then dropped onto the electrodes which are on an inclined surface to create a flow of the formulation using gravity. The nanowires then align along the gradient of the electric field and in the direction of the liquid flow. The frequency of the field can be adjusted to select nanowires with superior conductivity and lower trap density. 
In this work, flow-assisted DEP is used to create nanowire field effect transistors. Flow-assisted DEP has several advantages: it allows selection of nanowire electrical properties; control of nanowire length; placement of nanowires in specific areas; control of orientation of nanowires; and control of nanowire density in the device. 
The technique can be expanded to many other applications such as gas sensors and microwave switches. The technique is efficient, quick, reproducible, and it uses a minimal amount of dilute solution making it ideal for the testing of novel nanomaterials. Wafer scale assembly of nanowire devices can also be achieved using this technique, allowing large numbers of samples for testing and large-area electronic applications.

In this paper, flow assisted dielectrophoresis is demonstrated for the self-assembly of nanowire devices. The fabrication of a silicon nanowire field effect transistor is shown as an example.

Dieletroforese assistida por fluxo: Um método de baixo custo para a fabricação de dispositivos de solução-processable nanofio de alto desempenho

Flow-assisted dielectrophoresis (DEP) is an efficient self-assembly method for the controllable and reproducible positioning, alignment, and selection of ...