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Back side illuminated single photon avalanche diode imaging sensor with high short wavelength detection efficiency

  • US 9,331,116 B2
  • Filed: 01/15/2014
  • Issued: 05/03/2016
  • Est. Priority Date: 01/15/2014
  • Status: Active Grant
First Claim
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1. A single photon avalanche diode (SPAD), comprising:

  • an n doped epitaxial layer disposed in a first semiconductor layer;

    a p doped epitaxial layer formed over the n doped epitaxial layer on a back side of the first semiconductor layer, wherein the p doped epitaxial layer covers the entire back side of the first semiconductor layer;

    a multiplication junction defined at an interface between the n doped epitaxial layer and the p doped epitaxial layer, wherein a multiplication junction is reversed biased above a breakdown voltage such that a photon received through the back side of the first semiconductor layer triggers an avalanche multiplication process in the multiplication junction; and

    a p−

    doped guard ring region implanted in the n doped epitaxial layer surrounding the multiplication junction, wherein the p doped epitaxial layer covers the entire p−

    doped guard ring from the back side of the first semiconductor layer.

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