Semiconductor photodetector device with protection against ambient back light
The semiconductor photodetector device comprises a substrate of semiconductor material of a first type of electric conductivity, an epitaxial layer of an opposite second type of electric conductivity, a further epitaxial layer of the first type of electric conductivity and photodetectors. The epitaxial layer functions as a shielding layer for charge carriers (e − , h + generated by radiation that is incident from a rear side opposite the photodetectors.
1. A semiconductor photodetector device, comprising:
a substrate of semiconductor material of a first type of electric conductivity,
an epitaxial layer on the substrate, the epitaxial layer being doped for a second type of electric conductivity, which is opposite to the first type of electric conductivity,
a further epitaxial layer on the epitaxial layer, the further epitaxial layer being doped for the first type of electric conductivity, the epitaxial layer being arranged between the substrate and the further epitaxial layer,
an electric conductor shorting the substrate, the epitaxial layer and the further epitaxial layer; and
a photodetector or plurality of photodetectors arranged in the substrate or in the further epitaxial layer.
2. The semiconductor photodetector device of claim 1 , wherein
the photodetector or plurality of photodetectors is arranged in the further epitaxial layer.
3. The semiconductor photodetector device of claim 1 , further comprising:
a trench in the epitaxial layer and the further epitaxial layer, the trench reaching to the substrate, and
a metallization in the trench forming the electric conductor.
4. The semiconductor photodetector device of claim 1 , further comprising:
a trench in the epitaxial layer and the further epitaxial layer, the trench reaching to the substrate, and
a filling of electrically conductive poly silicon of the first type of conductivity in the trench forming the electric conductor.
5. The semiconductor photodetector device of claim 1 , wherein
the substrate is more highly doped for the first type of electric conductivity than the further epitaxial layer.
6. The semiconductor photodetector device of claim 1 , wherein
the first type of electric conductivity is p-type conductivity, and
the second type of electric conductivity is n-type conductivity.
7. A semiconductor photodetector device, comprising:
a substrate of semiconductor material, the substrate being doped for a first type of electric conductivity,
an epitaxial layer on the substrate, the epitaxial layer being doped for a second type of electric conductivity, which is opposite to the first type of electric conductivity,
a further epitaxial layer on the epitaxial layer, the further epitaxial layer being doped for the first type of electric conductivity, the epitaxial layer being arranged between the substrate and the further epitaxial layer,
a trench in the epitaxial layer and the further epitaxial layer, the trench reaching to the substrate,
an electric conductor in the trench, the electric conductor shorting the substrate, the epitaxial layer and the further epitaxial layer; and
a functional region of the further epitaxial layer, the functional region including a photodetector or plurality of photodetectors and an integrated circuit.
8. The semiconductor photodetector device according to claim 7 , wherein
the substrate is more highly doped than the further epitaxial layer,
the first type of electric conductivity is p-type conductivity, and
the second type of electric conductivity is n-type conductivity.