Optimized oxygen plasma etching of polyimide films for low loss optical waveguides
- 1 September 2002
- journal article
- Published by American Vacuum Society in Journal of Vacuum Science & Technology A
- Vol. 20 (5), 1587-1591
- https://doi.org/10.1116/1.1494816
Abstract
Sidewall roughness in waveguides is one of the consequences of a reactive ion etch (RIE) step. Sidewall roughness increases scattering losses and can impediment the scaling of waveguide dimensions to on-chip levels. This article presents results from our experiments on the study of optimal RIE conditions to minimize roughness on waveguide sidewalls. Roughness in planar polyimide films was studied for different plasma etch conditions to obtain an understanding of how roughness evolves. Pressure was found to be the dominant factor affecting interface roughness. RIE done at lower pressures was found to increase the roughness on the film surface. We propose that the roughness produced depends on the angle of incidence of the etchant species with respect to the surface the more obliquely the etchant species were incident on the surface, the lower was the roughness produced. Roughness produced on waveguide sidewalls was studied by measuring their propagation loss. For sidewalls, lower pressure RIE resulted in smoother sidewalls. This result was correlated with the previously obtained results for thin film surfaces. Based on our experiments we propose low pressure RIE to minimize sidewall roughness and fabricate low loss optical waveguides.Keywords
This publication has 13 references indexed in Scilit:
- Roughness evolution in polyimide films during plasma etchingApplied Physics Letters, 2001
- Effect of size and roughness on light transmission in a Si/SiO2 waveguide: Experiments and modelApplied Physics Letters, 2000
- Mechanisms for plasma and reactive ion etch-front rougheningPhysical Review B, 2000
- Polymer-based waveguide devices for WDM applicationsPublished by SPIE-Intl Soc Optical Eng ,1999
- Optical Properties of a Polyimide for Waveguide Applications in On-Chip InterconnectsMRS Proceedings, 1999
- Loss mechanisms in polyimide waveguidesJournal of Applied Physics, 1994
- Effect of side wall roughness in buried channel waveguidesIEE Proceedings - Optoelectronics, 1994
- Sheath collision processes controlling the energy and directionality of surface bombardment in O2 reactive ion etchingJournal of Applied Physics, 1988
- Dynamic Scaling of Growing InterfacesPhysical Review Letters, 1986
- The surface statistics of a granular aggregateProceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 1982