Enhancing silicon nitride waveguide performance: optimization of sidewall roughness for low-loss applications through resist reflowing via tree-based modeling of relevant processing parameters

Jakob Wilhelm Hinum-Wagner; Samuel Marko Hoermann; Gandolf Feigl; Christoph Schmidt; Jochen Kraft; Alexander Bergmann

doi:10.1117/12.3017081

18 June 2024 Enhancing silicon nitride waveguide performance: optimization of sidewall roughness for low-loss applications through resist reflowing via tree-based modeling of relevant processing parameters

Jakob Wilhelm Hinum-Wagner, Samuel Marko Hoermann, Gandolf Feigl, Christoph Schmidt, Jochen Kraft, Alexander Bergmann

Author Affiliations +

Proceedings Volume 13011, Data Science for Photonics and Biophotonics; 1301102 (2024) https://doi.org/10.1117/12.3017081
Event: SPIE Photonics Europe, 2024, Strasbourg, France

Abstract

This study introduces an innovative chip-upending technique to enhance the quality of silicon nitride waveguides by minimizing sidewall roughness, which is critical for reducing optical propagation losses. By reflowing the resist after development, we effectively control the resist expansion effect typically observed in standard procedures. Our analysis indicates that this method can decrease line edge roughness (LER). We employ atomic force microscopy (AFM) to measure the LER of the resist and the waveguide sidewalls via a special tilting technique, ensuring precise characterization of the surface topography. The fabrication is carried out by the choice of a suitable DOE for ensuring the statistical robustness in the evaluation process. Additionally, we conduct propagation and bend loss measurements at 850 nm across waveguides of various widths, with thicknesses ranging from 200 to 400 nm. These measurements in correlation with the roughness analysis confirms that sidewall roughness is indeed smoothed, resulting in notable improvements in light propagation efficiency. The versatility of the low-temperature reflow process is further demonstrated by its compatibility with several waveguide geometry alterations . The inclusion of tree-based modeling in optimizing relevant parameters in the fabrication, foremost the reflow parameters, thereby contributing to a more efficient and controlled reflow process. The findings suggest that our approach can be universally adopted for the fabrication of low-loss waveguides in photonic integrated circuits, with necessary wafer-to-wafer stability.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Jakob Wilhelm Hinum-Wagner, Samuel Marko Hoermann, Gandolf Feigl, Christoph Schmidt, Jochen Kraft, and Alexander Bergmann "Enhancing silicon nitride waveguide performance: optimization of sidewall roughness for low-loss applications through resist reflowing via tree-based modeling of relevant processing parameters", Proc. SPIE 13011, Data Science for Photonics and Biophotonics, 1301102 (18 June 2024); https://doi.org/10.1117/12.3017081

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available