Presentation
4 March 2019 Trimming of silicon-on-insulator devices via localised laser annealing (Conference Presentation)
Author Affiliations +
Proceedings Volume 10923, Silicon Photonics XIV; 109230A (2019) https://doi.org/10.1117/12.2507212
Event: SPIE OPTO, 2019, San Francisco, California, United States
Abstract
Silicon-on-Insulator devices are particularly sensitive to fabrication errors. As an example, a deviation in waveguide height or width of as little as 1nm translates directly to a 1nm offset in the transfer function of any interferometric devices (such as a ring resonator) constructed using the said waveguide. Therefore, even as fabrication tolerance continues to improve, post-fabrication treatment is often the only way of ensuring device uniformity for particularly demanding applications. This work proposes a novel approach for post fabrication trimming of SOI devices based on localised laser annealing of HSQ cladding layer. HSQ is a versatile material often used in fabrication of SOI devices as both the mask material for electron-beam lithography resist and as a cladding or planarization layer due to its similarity to conventional silica. However, unlike silica, the refractive index of HSQ can be changed significantly (up to ΔnHSQ = 3.26*10-2) by thermal processing. We utilise this property for trimming by cladding a conventional SOI waveguide optimised for TE propagation (height h=220 nm, width=500nm) with a layer of HSQ and then permanently changing the refractive index of the cladding via laser annealing. This approach allows us to select individual devices and only apply the change where necessary. As a demonstrator, we trim a resonance of a racetrack resonator by 1.3nm. The technique has proven to be robust with no parameter drift observed 7 days after trimming and no thermal cross-talk to neighbouring devices. Furthermore, unlike its predecessors, it is based on a standard fabrication process and does not require expensive specialised equipment.
Conference Presentation
© (2019) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Vera Biryukova, Graham J. Sharp, Charalambos Klitis, Sarah Ruddell, and Marc Sorel "Trimming of silicon-on-insulator devices via localised laser annealing (Conference Presentation)", Proc. SPIE 10923, Silicon Photonics XIV, 109230A (4 March 2019); https://doi.org/10.1117/12.2507212
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KEYWORDS
Annealing

Silicon

Cladding

Semiconductor lasers

Waveguides

Refractive index

Resonators

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