Evaluation of halogenated polyimide etching for optical waveguide fabrication by using inductively coupled plasma

Han, Ki Jun; Kim, Jung-Hee; Jang, Woo–Hyuk

doi:10.1002/1097-4628(20010103)79:1<176::aid-app200>3.0.co;2-7

Cited by 5 publications

(2 citation statements)

References 13 publications

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“…There should be no polymer passivation layer formed on the sidewalls of the waveguides when using the CF 4 /O 2 plasma to etch the As 2 S 3 , since the O 2 plasma is very effective to remove the polymer layer deposited from any carbon fluoride gases, 20 and the oxygen acts as scavenger of CF x radicals, reducing the sources for the polymer formation. We have originally suspected that there could be an oxide layer formed on the sidewall of the waveguide, which might act as a passivation layer to inhibit the undercutting.…”

Section: Profile Of the Etched Waveguidesmentioning

confidence: 99%

Dry-etch of As2S3 thin films for optical waveguide fabrication

Ruan

Luther‐Davies

et al. 2005

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Plasma etching to As 2 S 3 thin films for optical waveguide fabrication has been studied using a helicon plasma etcher. The etching effects using the processing gases or gas mixtures of O 2 , Ar, and CF 4 were compared. It was found that the O 2 plasma had no chemical etching effect to the As 2 S 3 , but it could oxidize the surface of the As 2 S 3. The Ar plasma provided a strong ion sputtering effect to the films. The CF 4 plasma exhibited a too strong chemical etch to the As 2 S 3 , leading to serious undercutting and very rough sidewalls of the waveguides. Ar and O 2 gases were compared as the additives to dilute the CF 4 processing gas. The etch rate of the As 2 S 3 was reduced dramatically from over 2000 nm/ min to a few hundred nm/min when the pure CF 4 gas was heavily diluted with 70% Ar or O 2 gas. The undercutting and sidewall roughness of the etched waveguides were also decreased greatly when above dilution was made, which was associated with an enormous weakening of the isotropic chemical etch induced by neutral reactants in the plasma. In addition, the O 2 showed a better dilution effect than the Ar in reducing the etch rate of the As 2 S 3 ; and the O 2 /CF 4 plasma also enabled a much lower erosion rate to Al mask layers than the Ar/ CF 4 plasma at similar plasma conditions. The As 2 S 3 waveguides with near vertical and very smooth sidewalls were obtained using an optimized O 2 /CF 4 plasma. Moreover, the etching behaviors and mechanisms were explained base on the etching results, and on the characteristics of the applied plasma diagnosed using Langmuir probe and optical spectroscopy techniques.

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Section: Profile Of the Etched Waveguidesmentioning

confidence: 99%

Dry-etch of As2S3 thin films for optical waveguide fabrication

Ruan

Luther‐Davies

et al. 2005

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…In contrast, we need to achieve a sidewall angle of 90°± 1°to achieve high optical efficiency. a͒ Electronic mail: nordin@ee.byu.edu While oxygen is typically used as the primary gas in plasma etching of polymers due to its high reactivity, ion induced lateral spontaneous etching is also present, 14,15 which usually results in linewidth broadening and nonvertical sidewalls, particularly for etches conducted at room temperature or above. To reduce or eliminate this lateral etching, a gas can be added to the plasma to create a protective passivation layer on the sidewalls.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic high aspect ratio etch for perfluorcyclobutyl polymers with stress relief technique

Rahmanian

Kim

Nordin

2006

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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The authors have developed an anisotropic, high aspect ratio (18:1) etch for perfluorocyclobutyl (PFCB) polymers with trenches as narrow as 800nm using a CO∕O2 etch chemistry in an inductively coupled plasma reactive ion etcher. Anisotropy is achieved by carbon sidewall passivation. The motivation for this etch development is to use the air trenches as very compact waveguide splitters [S. Kim et al., Opt. Eng. 45, 054602 (2006)]. The authors report a new trench widening mechanism due to tensile stress of the PFCB films and a method of avoiding this widening through the use of additional stress relief trenches on both sides of the desired trench.

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