resumo
A special surface pre-treatment protocol consisting of four steps is proposed to provide high adhesion levels for CVD diamond by hot-filament technique. In step 1, the silicon nitride ceramic substrates are surface ground with 15 mu m diamond slurry and mirror-like polished with colloidal silica (0.05 mu m). In step 2, plasma etching with CF(4) (PE), mechanical anchoring is promoted due to the surface roughness increment. Surface activation (SA) is the following step, where the substrates are subjected to CVD diamond growth conditions for a short time (30 min), leading to the deposition of an amorphous carbon layer responsible for enhancing the nucleation density and the further growth of diamond during early stages of deposition. The final step 4 is 0.5-1 mu m diamond powder seeding in an ultrasonic bath. The results show that the Si(3)N(4) ceramic surface modified by the surface pre-treatment protocol allowed a high nucleation density promoting a continuous and homogeneous film of equally sized diamond grains, at a growth rate of ap. 1.5 mu m h(-1). Brale tip indentation tests confirmed that highly adherent films are thus produced (no delamination under 900 N). (C) 2010 Elsevier B.V. All rights reserved.
palavras-chave
SILICON-NITRIDE; RAMAN-SCATTERING; THIN-FILMS; NUCLEATION; DEPOSITION; GROWTH; PRETREATMENTS; QUALITY; HFCVD; NCD
categoria
Materials Science; Physics
autores
Amaral, M; Almeida, F; Fernandes, AJS; Costa, FM; Oliveira, FJ; Silva, RF
nossos autores
Filipe José Alves de Oliveira
Investigador Principal
Flávia Aparecida de Almeida
Bolseiro de pós-Doutoramento
Margarida Isabel dos Santos Amaral
Bolseiro de pós-Doutoramento
Rui Ramos Ferreira e Silva
Professor associadoagradecimentos
M. Amaral and F. Almeida acknowledge the FCT for the grants SFRH/BPD/26787/2006 and SFRH/BPD/34869/2007, respectively.