Thick film hydrogen silsesquioxane planarization for passive component technology associated with electronic-photonic integrated circuits

Abstract

Thick film hydrogen silsesquioxane planarization for passive component technology associated with electronic-photonic integrated circuits.

EML Based on Lumped Configuration, Identical Epitaxial Layer and HSQ Planarization

“…The electrode of the EAM is designed with a circular pad of 60 µm diameter integrated on a thick low-permittivity insulator. The HSQ planarization method explained in [10], is used to fabricate the insulating layer. This approach is for the first time applied here to reduce the bond-pad capacitance in this type of photonic integration.…”

“…The capacitance can be reduced by using a low-permittivitymaterial as the insulator for the bond pad which can also provide the necessary planarization. Conventional planarization methods such as those based on BCB (benzocyclobutene) or polyimide materials are difficult to apply or are incompatible with some photonic integration steps [10]. Another option, Hydrogen Silsesquioxane (HSQ) planarization is commonly used in standard integrated circuits for multilevel metal interconnects [11].…”

“…Based on the spin-on coating technique, film thicknesses up to 800 nm in a single spin can be achieved. Thicker dielectricfilms of up to 10 µm can be planarized using the method explained in [10], [13].…”

Novel Electroabsorption Modulator Design Based on Coplanar Waveguide Configuration

“…An additional etch step is needed to deep etch the EAM section. The lowpermittivity film required for the connection to the EAM was built up using successive HSQ spin-on coatings [9], with 5 spin coatings required to obtain a 6 µm film thickness. After each spin coating, the sample was patterned using Electron Beam (EB), followed by deposition of 40 nm of SiO2 using Plasma-Enhanced Chemical Vapor Deposition (PECVD).…”

Traveling-Wave Electroabsorption Modulated Laser Based on Identical Epitaxial Layer Scheme and HSQ Planarization

“…In this work we report, for the first time, an EML integrated with TW EAM based on the identical epitaxial layer design and using a side-wall grating (SWG) for the DFB laser. A novel planarization method based on hydrogen silsesquioxane (HSQ) spin-on coating [4], was used to create a 2.4-µm-thick low-permittivity film (εr ≈ 3.8) on which the TW electrode was fabricated. The EML chip comprised a DFB, EAM, and semiconductor optical amplifier (SOA) of lengths 600 µm, 150 µm, and 320 µm, respectively.…”