Semiconductor light detecting element having silicon substrate and conductor

Patent metadata

Field	Value
Publication number	US-9293499-B2
Application number	US-201113634249-A
Country	US
Kind code	B2
Filing date	Feb 22, 2011
Priority date	Apr 14, 2010
Publication date	Mar 22, 2016
Grant date	Mar 22, 2016

Abstract

A semiconductor light detecting element is provided with a silicon substrate having a semiconductor layer, and an epitaxial semiconductor layer grown on the semiconductor layer and having a lower impurity concentration than the semiconductor layer; and conductors provided on a surface of the epitaxial semiconductor layer. A photosensitive region is formed in the epitaxial semiconductor layer. Irregular asperity is formed at least in a surface opposed to the photosensitive region in the semiconductor layer. The irregular asperity is optically exposed.

First claim

The invention claimed is:

1. A semiconductor light detecting element comprising:
a silicon substrate having a semiconductor layer having a first impurity concentration, and an epitaxial semiconductor layer grown on the semiconductor layer and having a second impurity concentration lower than the first impurity concentration; and
a conductor provided on a surface of the epitaxial semiconductor layer,
wherein a photosensitive region is formed in the epitaxial semiconductor layer,
wherein irregular asperity is formed at least in a surface opposed to the photosensitive region in the semiconductor layer,
wherein the irregular asperity is optically exposed,
wherein the irregular asperity is formed by applying pulsed laser light,
light incident into the silicon substrate is scattered, diffused, or reflected by the irregular asperity to travel in the silicon substrate, and
the photosensitive region is configured to generate an electric charge in response to incident light.

2. The semiconductor light detecting element according to claim 1 ,
wherein the conductor comprises a photogate electrode provided on the surface of the epitaxial semiconductor layer, and first and second gate electrodes provided adjacent to the photogate electrode on the surface of the epitaxial semiconductor layer,
the semiconductor light detecting element further comprising:
first and second semiconductor regions formed in the epitaxial semiconductor layer, for reading out respective charges flowing from a region immediately below the photogate electrode to immediately below the first and second gate electrodes,
wherein the irregular asperity is formed at least in a surface opposed to the region immediately below the photogate electrode in the semiconductor layer.

3. The semiconductor light detecting element according to claim 1 ,
wherein a photodiode to generate charge in a quantity according to an intensity of incident light is formed as the photosensitive region in the epitaxial semiconductor layer, and
wherein the irregular asperity is formed at least in a surface opposed to the photodiode in the semiconductor layer.

4. The semiconductor light detecting element according to claim 3 , further comprising:
an amplification transistor to output a voltage value according to a quantity of charge input at a gate terminal thereof;
a transfer transistor to transfer the charge generated in the photodiode, to the gate terminal of the amplification transistor;
a discharge transistor to discharge the charge at the gate terminal of the amplification transistor; and
a selection transistor to selectively output the voltage value output from the amplification transistor.

5. The semiconductor light detecting element according to claim 1 ,
wherein the epitaxial semiconductor layer has a plurality of multiplication regions forming pn junctions at interfaces to the semiconductor layer and configured to achieve avalanche multiplication of carriers generated with incidence of light to be detected,
wherein the conductor includes a plurality of resistors each having two end portions, provided for the respective multiplication regions, electrically connected to the epitaxial semiconductor layer through one of the end portions, and connected to a signal conductor line through the other of the end portions, and
wherein the irregular asperity is formed at least in a surface opposed to each of the multiplication regions in the semiconductor layer.

6. The semiconductor light detecting element according to claim 1 ,
wherein the epitaxial semiconductor layer has a plurality of multiplication regions to achieve avalanche multiplication of carriers generated with incidence of light,
wherein semiconductor regions forming pn junctions at interfaces to the epitaxial semiconductor layer are formed corresponding to the multiplication regions in the epitaxial semiconductor layer,
wherein the conductor includes a plurality of resistors each having two end portions, provided for the respective semiconductor regions in the epitaxial semiconductor layer, electrically connected to the respective semiconductor regions in the epitaxial semiconductor layer through one of the end portions, and connected to a signal conductor line through the other of the end portions, and
wherein the irregular asperity is formed at least in a surface opposed to each of the semiconductor regions in the semiconductor layer.

Assignees

• Mase Mitsuhito
• Sakamoto Akira
• Suzuki Takashi
• Yamazaki Tomohiro
• Fujii Yoshimaro
• Hamamatsu Photonics Kk

Inventors

• Mase Mitsuhito
• Sakamoto Akira
• Suzuki Takashi
• Yamazaki Tomohiro
• Fujii Yoshimaro

Classifications

• H10F77/70

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• H10F39/807 Primary

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  Electricity · mapped topic