Back side illuminated single photon avalanche diode imaging sensor with high short wavelength detection efficiency
First Claim
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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Accused Products
Abstract
A single photon avalanche diode (SPAD) includes an n doped epitaxial layer disposed in a first semiconductor layer. A p doped epitaxial layer is above the n doped epitaxial layer on a back side of the first semiconductor layer. A multiplication junction is defined at an interface between the n doped epitaxial layer and the p doped epitaxial layer. 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. A p− doped guard ring region is implanted in the n doped epitaxial layer surrounding the multiplication junction.
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Citations
18 Claims
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1. A single photon avalanche diode (SPAD), comprising:
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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. - View Dependent Claims (2, 3, 4, 5)
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6. An imaging sensor system, comprising:
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a first semiconductor layer of a first wafer; a single photon avalanche diode (SPAD) imaging array including a plurality of pixels formed in the first semiconductor layer, wherein each pixel includes a SPAD including; an n doped epitaxial layer disposed in the 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; 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;a second semiconductor layer of a second wafer bonded to the first wafer; a plurality of digital counters formed in the second semiconductor layer and electrically coupled to the SPAD imaging array, wherein each one of the plurality of digital counters is coupled to count output pulses generated by a respective one of the plurality of pixels. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification