The fabrication of thick SiO2 layer by anodization

Silicon-based silica waveguide (SiO2/Si) devices have huge applications in optical telecommunication. SiO2 up to 25-mu m thick is necessary for some p assive SiO2/Si waveguide devices. Oxidizing porous silicon to obtain thick SiO2 as cladding layer is presented. The experimental results of porous lay er and oxidized porous layer formation were given. The relationship between cracking of SiO2 and temperature varying rate was given experimentally. Su ch conclusions are drawn: oxidation rate of porous silicon is several order s faster than that of bulk silicon; appropriate temperature variation rate during oxidation can prevent SiO2 on silicon substrates from cracking, and 25 mu m thick silicon dioxide layer has been obtained. (C) 2000 Elsevier Sc ience B.V. All rights reserved.