Optical waveguide fabrication by combination of spin-on-glass and plasma-enhanced chemical vapor deposition for optoelectronic integration

Abstract

Low-loss optical waveguides for optoelectronic integration were realized by the combination of spin-on- glass (SOG) and plasma-enhanced chemical vapor deposi- tion (PECVD). Undercladdings of 20-mm thickness together with cores of 6-mm height and 8-mm width were formed on Si substrates by PECVD and reactive ion etching. Overclad- dings were formed by a combination of SOG and PECVD SiO2 films. This method successfully filled narrow gaps be- tween cores of optical circuits. The refractive index of over- claddings was adjusted by SOG curing and fluorine incorpo- ration in PECVD SiO2 films. A buried-type optical waveguide formed by the combination of SOG and PECVD showed single-mode propagation. Propagation losses and polariza- tion dependent losses at the 1.3-mm wavelength were mea- sured to be 0.3 dB/cm and below 0.15 dB, respectively. © 2003 Society of Photo-Optical Instrumentation Engineers.