Solid-state imaging element and method for manufacturing the same
View Patent ↗A solid-state imaging element includes a layered substrate made of silicon and composed of, for example, an N-type substrate, a P-type layer, and an N-type layer. In the layered substrate, an imaging region in which a plurality of pixels are arranged and a peripheral circuit region are formed. A recess reaching the reverse face of the P-type layer is formed in a reverse face portion of the layered substrate in the imaging region, and a reflective film is formed on at least the inner face of the recess. Light is reflected on the reverse face and the obverse face of the layered substrate.
1. A solid-state imaging element in which an imaging region in which a plurality of pixels each including a photoelectric converter and a transistor are provided and a peripheral circuit region are formed, comprising:
a substrate including a silicon substrate and a first semiconductor layer containing a P-type impurity at a concentration higher than that in the silicon substrate and having an obverse face on which the plurality of pixels are provided and a reverse face portion,
wherein a recess reaching the reverse face of the first semiconductor layer is formed in the reverse face portion of the substrate in the imaging region.
2. The solid-state imaging element of claim 1 , wherein
the substrate further includes a second semiconductor layer provided on the first semiconductor layer.
3. The solid-state imaging element of claim 2 , wherein
the first semiconductor layer and the second semiconductor layer are formed by epitaxial growth.
4. The solid-state imaging element of claim 1 , wherein
the first semiconductor layer is formed by ion implantation to form an impurity concentration peak, and
a part under the photoelectric converter which forms the impurity concentration peak is located shallower than a part under the transistor which forms the impurity concentration.
5. The solid-state imaging element of claim 1 , further comprising:
a light reflective film formed on an inner face of the recess.
6. The solid-state imaging element of claim 1 , further comprising:
in the peripheral circuit region, a substrate contact part including a substrate contact provided on the substrate and a pad connected to the substrate contact.
7. The solid-state imaging element of claim 1 , further comprising:
a silicon germanium layer formed on a region of the substrate in which the photoelectric converter is formed and having the same conductivity as the first semiconductor layer.
8. The solid-state imaging element of claim 2 , wherein
a total thickness of the first semiconductor layer and the second semiconductor layer in a region where the recess is formed is in a range between 5 μm and 8 μm, both inclusive.
9. The solid-state imaging element of claim 1 , further comprising:
a wiring over the photoelectric converter,
wherein the first semiconductor layer is in contact with the bottom of the photoelectric converter.
10. The solid-state imaging element of claim 1 , wherein
the first semiconductor layer has an impurity concentration in a range between 1×10 18 atoms/cm 3 and 1×10 21 atoms/cm 3 , both inclusive.
11. The solid-state imaging element of claim 5 , wherein
the light reflective film is made of a metal material, a dielectric material, or an organic material.