Detalhes bibliográficos
| Ano de defesa: |
2012 |
| Autor(a) principal: |
Esteves, Christian Roberto Becker
 |
| Orientador(a): |
Papaléo, Ricardo Meurer
|
| Banca de defesa: |
Não Informado pela instituição |
| Tipo de documento: |
Dissertação
|
| Tipo de acesso: |
Acesso aberto |
| Idioma: |
por |
| Instituição de defesa: |
Pontifícia Universidade Católica do Rio Grande do Sul
|
| Programa de Pós-Graduação: |
Programa de Pós-Graduação em Engenharia e Tecnologia de Materiais
|
| Departamento: |
Faculdade de Engenharia
|
| País: |
BR
|
| Palavras-chave em Português: |
|
| Área do conhecimento CNPq: |
|
| Link de acesso: |
http://tede2.pucrs.br/tede2/handle/tede/3258
|
Resumo: |
In this study, we investigated the formation and thermal stability of PMMA ultrathin films of different thicknesses h from 2 to 50 nm deposited on Si wafers. To observe the effects caused by temperature in the surface morphology annealings at predetermined times were performed in air, N2 or vacuum atmospheres, at temperatures above (150 ° C), closed to (100 and 120 ° C) or much below the glass transition temperature Tg at the material. We also studied the effect of pre-irradiation with high-energy ions (300 keV and 2 MeV of H+ and 18 MeV of Au7+) on the stability of the films in vacuum. The as deposited films showed smooth and uniform surfaces, except in a few movies which presented circular holes of sizes between 100 and 300 nm in some regions. We observed a slight crease in the roughness of the films with increasing thickness up to h ~ 10 nm. For films with h> 10 nm, the root mean square roughness (RRMS) tended to stabilize around ~ 0.25 nm. The films maintained in air at ambient temperature showed, in some cases an aging effect with a increase in roughness of up to 20% after 60 days. For short periods, no significant effect was observed RRMS increased in all films treated at temperatures near or above the Tg values for all kinds of atmospheres. The magnitude of variation was however larger for films treated in vacuum. The roughness of the films reached up to three times the initial value after a period of 24h. In general, the thinnest films were more stable in all different environments. This result may be linked to the predominance of polar interactions at the interface (between the native oxide on the silicon surface and COO groups of PMMA) in the ultrathin films. The irradiation with heavy ions increased the roughness of the films for all fluences used. Irradiation with light ions, in the two energies used, accelerated the destabilization of the films at low doses, but generated an improvement in stability in intermediate doses. These effects can be attributed to the types of changes introduced by the ions in each energy regime. For the Au+ ion sputtering and damage are much more pronounced favoring formation of holes in the surface. For H+ ions predominate the diluted effects of secondary electrons that can increase the mobility of the chains via the fission process at low fluences, but eventually favoris crosslinking and stabilization for higher doses |
