Low temperature PECVD processes for the fabrication of integrated symmetrical resonant UV210 Organic/Semiconductor structures

Jordan Gastebois (1) , Nathalie Coulon (1) , Hervé Cormerais (2, 1) , Christophe Levallois (3, 4) , Eric Bêche (5) , Jerome Esvan (6) , Alain Moréac (7, 8) , Hervé Lhermite (1) , Lucas Garnier (1) , Bruno Bêche (9, 1)

1 IETR - Institut d'Électronique et des Technologies du numéRique
2 CentraleSupélec [campus de Rennes]
3 FOTON - Institut des Fonctions Optiques pour les Technologies de l'informatiON
4 INSA Rennes - Institut National des Sciences Appliquées - Rennes
5 PROMES - Procédés, Matériaux et Energie Solaire
6 CIRIMAT - Centre interuniversitaire de recherche et d'ingénierie des matériaux
7 IPR - Institut de Physique de Rennes
8 ScanMAT - Synthèse Caractérisation Analyse de la Matière
9 UR - Université de Rennes

The resonant structures used as sensors for investigating specific dark and opaque substances may pose difficulties due to their potential aggressiveness towards photonic chips and the risk of destruction upon contact. To avoid it, this study presents a detailed description of a novel symmetrical waveguide structure with UV210 enclosed between Si/SiO2 bi-layers implemented for integrated photonics. The fabrication process is thoroughly explained, accompanied by various analyses conducted for characterizations purposes. The structure is composed of an organic UV210 material developed using deep UV lithography at 248 nm and fabricated onto an oxidized silicon layer, resulting in a Si/SiO2 bi-layer configuration. This process enables the fabrication of μm-scale access waveguides and racetrack Micro-Resonators (MRs) with a 400-nanometers gap. Several multilayer families have been produced using various low-temperature PECVD processes to obtain symmetrical Si/SiO2/UV210/Si/SiO2 structures and then properly characterized using non-destructive analyses and imaging techniques. The advantage of structural symmetry is primarily related to the electromagnetism and guidance equations, which eliminate the requirement for a cut-off thickness (or frequency), enabling significant miniaturization. Additionally, the upper cladding composed of a Si/SiO2 bi-layer offers protection against potentially aggressive substances directly in contact with the organic waveguide core and MRs. Different bi-layer upper cladding families, produced under various PECVD conditions, were characterized using XPS to understand the bonding mechanism between the silicon and UV210 organic. In addition, ellipsometric analyses were conducted to determine the real and imaginary components of the refractive index of the global structure and the upper cladding bi-layer. Structure imaging were obtained by Raman analyses and optical statistical measurements were conducted on four different types of heterostructures, with silica temperatures ranging from 120°C to 150°C during the second PECVD process. The resonance analysis, performed through Free Spectral Range (FSR) measurements, allowed us to draw conclusions regarding the stability and reproducibility of the fabrication process, as well as the impact of PECVD processes conditions on the optical measurements. Such optoelectronic resonant elements and hybrid heterostructures enable the investigation of aggressive substances in direct contact.

Keywords: Integrated organic photonic with PECVD Semiconductor-On-Insulator with organic (SOI on Org.) Ellipsometric analyses Raman analyses XPS analyses Resonators cavities; Integrated organic photonic with PECVD; Semiconductor-On-Insulator with organic (SOI on Org.); Ellipsometric analyses; Raman analyses; XPS analyses; Resonators cavities

Domains: Micro and nanotechnologies/Microelectronics; Physics [physics]; Materials Science [cond-mat.mtrl-sci]; Chemical Physics [physics.chem-ph]; Electromagnetism; Materials; Optics / Photonic

Jordan Gastebois, Nathalie Coulon, Hervé Cormerais, Christophe Levallois, Eric Bêche, et al.. Low temperature PECVD processes for the fabrication of integrated symmetrical resonant UV210 Organic/Semiconductor structures. Materials Today Communications, 2024, 39 (109173), pp.1-13. ⟨10.1016/j.mtcomm.2024.109173⟩. ⟨hal-04573857⟩