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.
CITATION STYLE
Ono, A., Hashimoto, K., & Teranishi, N. (2021). Near-infrared sensitivity improvement by plasmonic diffraction for a silicon image sensor with deep trench isolation filled with highly reflective metal. Optics Express, 29(14), 21313. https://doi.org/10.1364/oe.428314
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