Open AccessNear-infrared sensitivity improvement by plasmonic diffraction for a silicon image sensor with deep trench isolation filled with highly reflective metal
Author(s) -
Akira Ono,
Kazuma Hashimoto,
Nobukazu Teranishi
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.428314
Subject(s) - materials science , optics , silicon , diffraction , plasmon , optoelectronics , grating , surface plasmon polariton , diffraction grating , shallow trench isolation , diffraction efficiency , surface plasmon , trench , layer (electronics) , nanotechnology , physics
We propose a plasmonic diffraction structure combined with deep trench isolation (DTI) filled with highly reflective metal to enhance the near-infrared (NIR) sensitivity of image sensors. The plasmonic diffraction structure has a silver grating on the light-illuminated surface of a typical silicon backside-illuminated CMOS image sensor. The structural parameters of the silver grating were investigated through simulations, and the mechanism of the NIR sensitivity enhancement was clarified. Under the quasi-resonant conditions of surface plasmon polaritons, incident NIR light effectively diffracted as a propagating light to the sensor silicon layer. The diffracted light travelled back and forth between the DTIs. The effective propagation length in silicon was extended to six times by silver-filled DTI, resulting in approximately five times improvement of the 3-µm-thick silicon absorption at a wavelength of 940 nm.