Damascene Process Development for Low-Loss Photonics Devices with Applications in Frequency Comb

Silicon nitride (SiN) is emerging as a material of choice for photonic integrated circuits (PICs) due to its ultralow optical losses, absence of two-photon absorption in telecommunication bands, strong Kerr nonlinearity and high-power handling capability. These properties make SiN particularly well-...

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Bibliographic Details
Published inPhotonics Vol. 11; no. 4; p. 375
Main Authors Zhou, Qiaoling, Jin, Yejia, Zheng, Shaonan, Zhao, Xingyan, Qiu, Yang, Jia, Lianxi, Dong, Yuan, Zhong, Qize, Hu, Ting
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.04.2024
Subjects
Annealing
Chemical vapor deposition
damascene process
Delay lines
Etching
Film thickness
Hydrogen bonds
Integrated circuits
Lasers
Low pressure
Nitrides
Nonlinear systems
Optical frequency
optical frequency comb
Photon absorption
Photonics
photonics devices
R&D
Research & development
Silicon
Silicon nitride
Silicon wafers
Stress
Technology application
Waveguides
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Summary:Silicon nitride (SiN) is emerging as a material of choice for photonic integrated circuits (PICs) due to its ultralow optical losses, absence of two-photon absorption in telecommunication bands, strong Kerr nonlinearity and high-power handling capability. These properties make SiN particularly well-suited for applications such as delay lines, chip-scale frequency combs and narrow-linewidth lasers, especially when implemented with thick SiN waveguides, which is achieved through low-pressure chemical vapor deposition (LPCVD). However, a significant challenge arises when the LPCVD SiN film thickness exceeds 300 nm on an 8-inch wafer, as this can result in cracking due to high stress. In this work, we successfully develop a damascene process to fabricate 800 nm-thick SiN photonics devices on an 8-inch wafer in a pilot line, overcoming cracking challenges. The resulting 2 × 2 multimode interference (MMI) coupler exhibits low excess loss (−0.1 dB) and imbalance (0.06 dB) at the wavelength of 1310 nm. Furthermore, the dispersion-engineered SiN micro-ring resonator exhibits a quality (Q) factor exceeding 1 × 106, enabling the generation of optical frequency combs. Our demonstration of photonics devices utilizing the photonics damascene process sets the stage for high-volume manufacturing and widespread deployment.
ISSN:2304-6732
2304-6732
DOI:10.3390/photonics11040375