# US 11,444,110 B2 · Pixel comprising a charge storage zone

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- Number: US 11,444,110 B2
- Document ID: US11444110B2
- Status: Granted
- Kind: B2
- Application number: 17/225,329
- Filed: 2021-04-08
- Published: 2021-11-04
- Granted: 2022-09-13
- Earliest claimed: 2020-04-30
- Assignees: STMicroelectronics (Crolles 2) SAS
- Applicants: STMicroelectronics (Crolles 2) SAS
- Inventors: Boris Rodrigues Goncalves; Frederic Lalanne
- Web page: https://patentgrep.com/patent/US11444110B2

## CPC

- H10F 39/80373: {characterised by the gate of the transistor}
- H10F 39/807: {Pixel isolation structures}
- G01S 7/4863: Detector arrays, e.g. charge-transfer gates
- G01S 7/4914: of detector arrays, e.g. charge-transfer gates
- H04N 25/703: SSIS architectures incorporating pixels for producing signals other than image signals
- H04N 25/78: Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters
- H10F 39/18: Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors
- H10F 39/802: {Geometry or disposition of elements in pixels, e.g. address-lines or gate electrodes}
- H10F 39/8027: {Geometry of the photosensitive area}
- H10F 39/8037: {the integrated elements comprising a transistor}
- H10F 39/80377: {characterised by the channel of the transistor, e.g. channel having a doping gradient}
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A pixel includes a photoconversion zone, an insulated vertical electrode and at least one charge storage zone. The photoconversion zone belongs to a first part of a semiconductor substrate and each charge storage zone belongs to a second part of the substrate physically separated from the first part of the substrate by the insulated vertical electrode.

## Claims

### Claim 1

A pixel comprising:
a photoconversion zone;
an insulated vertical electrode; and
at least one charge storage zone;
wherein the photoconversion zone belongs to a first part of a semiconductor substrate;
wherein each charge storage zone belongs to a second part of the semiconductor substrate that is physically separated from the first part of the semiconductor substrate by the insulated vertical electrode;
wherein the insulated vertical electrode passes through the semiconductor substrate from a first face of the semiconductor substrate; and
for each charge storage zone:
a first doped zone in contact with said charge storage zone in the second part;
a second doped zone in the first part;
a gate resting on the first face of the semiconductor substrate between the photoconversion zone and said second doped zone; and
an electrical connection between the first doped zone and the second doped zone;
wherein the insulated vertical electrode is configured, for each charge storage zone, to electrically and optically insulate the first part of the semiconductor substrate comprising the photoconversion zone and the second doped zone from the second part of the semiconductor substrate comprising the charge storage zone and the first doped zone.

### Claim 2 (depends on 1)

The pixel according to claim 1, wherein, for each charge storage zone, said electrical connection is arranged outside the semiconductor substrate, above the first face of the semiconductor substrate.

### Claim 3 (depends on 1)

The pixel according to claim 1, wherein, each charge storage zone is delimited laterally, widthwise, by two portions of the insulated vertical electrode that are parallel and facing one another, the first doped zone in contact with the charge storage zone being arranged at one end of the charge storage zone taken lengthwise.

### Claim 4 (depends on 1)

The pixel according to claim 1, wherein:
the semiconductor substrate is doped with a first type of conductivity;
the photoconversion zone comprises a layer doped with a second type of conductivity, arranged in the semiconductor substrate on the first face of the semiconductor substrate;
for each charge storage zone, the first and second doped zones are arranged in the semiconductor substrate, on the first face of the semiconductor substrate, and are doped with the second type of conductivity; and
each charge storage zone comprises a region doped with the second type of conductivity, arranged in the semiconductor substrate, on the first face of the semiconductor substrate.

### Claim 5 (depends on 4)

The pixel according to claim 4, wherein, for each charge storage zone, the first and second doped zones have a same doping level.

### Claim 6 (depends on 4)

The pixel according to claim 4, wherein, for each charge storage zone, the first and second doped zones have a same doping level as the layer of the photoconversion zone.

### Claim 7 (depends on 4)

The pixel according to claim 4, wherein, for each charge storage zone, the region of the charge storage zone is more greatly doped than the first doped zone.

### Claim 8 (depends on 4)

The pixel according to claim 4, wherein, for each charge storage zone, said gate rests on a channel region extending from the second doped zone to the layer of the photoconversion zone, the channel region being less heavily doped with the second type of conductivity than the layer of the photoconversion zone and the second doped zone.

### Claim 9 (depends on 8)

The pixel according to claim 8, wherein, for each charge storage zone, the channel region comprises a first portion and a second portion less heavily doped than the first portion, the second portion extending from the layer of the photoconversion zone to the first portion and the first portion extending from the second portion to the second doped zone.

### Claim 10 (depends on 8)

The pixel according to claim 8, wherein, for each charge storage zone, the second doped zone is separated from the layer of the photoconversion zone by the channel region and by a region of the semiconductor substrate doped with the first type of conductivity.

### Claim 11 (depends on 1)

The pixel according to claim 1, wherein, for each charge storage zone, the pixel comprises:
a doped reading zone arranged in the semiconductor substrate on the side of the first face in the second part of the semiconductor substrate with the charge storage zone; and
an additional gate resting on a portion of the semiconductor substrate extending between the charge storage zone and the reading zone, the additional gate spreading to the charge storage zone.

### Claim 12 (depends on 1)

The pixel according to claim 1, wherein at least two charge storage zones belong to a same second part of the semiconductor substrate.

### Claim 13

A pixel comprising:
a photoconversion zone;
an insulated vertical electrode; and
at least one charge storage zone;
wherein the photoconversion zone belongs to a first part of a semiconductor substrate;
wherein each charge storage zone belongs to a second part of the semiconductor substrate that is physically separated from the first part of the semiconductor substrate by the insulated vertical electrode; and
a circuit configured:
to apply a first polarization potential to the first part of the semiconductor substrate; and
for each charge storage zone:
to apply the first polarization potential to the second part of the semiconductor substrate during each reading phase of the charge storage zone; and
to apply a second polarization potential to the second part of the semiconductor substrate outside of reading phases of said charge storage zone;
wherein the first and second polarization potentials are configured so that a potential well in the charge storage zone is deeper when the second polarization potential is applied than when the first polarization potential is applied.

### Claim 14 (depends on 13)

The pixel according to claim 13, wherein at least two charge storage zones belong to a same second part of the semiconductor substrate.

### Claim 15

A sensor, comprising a plurality of pixels, wherein each pixel comprises:
a photoconversion zone;
an insulated vertical electrode; and
at least one charge storage zone;
wherein the photoconversion zone belongs to a first part of a semiconductor substrate; and
wherein each charge storage zone belongs to a second part of the semiconductor substrate that is physically separated from the first part of the semiconductor substrate by the insulated vertical electrode; and
wherein two adjacent pixels share same first part of the semiconductor substrate.

### Claim 16 (depends on 15)

The sensor according to claim 15, wherein two adjacent pixels share a same second part of the semiconductor substrate.

### Claim 17 (depends on 15)

The sensor according to claim 15, further comprising a circuit configured:
to apply a first polarization potential to the first part of the semiconductor substrate; and
for each charge storage zone:
to apply the first polarization potential to the second part of the semiconductor substrate comprising the storage zone during each reading phase of the charge storage zone; and
to apply a second polarization potential to the second part outside of reading phases of said charge storage zone;
wherein the first and second polarization potentials are configured so that a potential well in the charge storage zone is deeper when the second polarization potential is applied to the second part of the semiconductor substrate than when the first polarization potential is applied to the second part of the semiconductor substrate.

### Claim 18

A control method for a pixel that includes a photoconversion zone, an insulated vertical electrode, and at least one charge storage zone, wherein the photoconversion zone belongs to a first part of a semiconductor substrate, and wherein each charge storage zone belongs to a second part of the semiconductor substrate that is physically separated from the first part of the semiconductor substrate by the insulated vertical electrode, comprising:
polarizing the first part of the semiconductor substrate with a first polarization potential; and
for each charge storage zone:
polarizing the second part of the semiconductor substrate with the first polarization potential during each reading phase of the charge storage zone; and
polarizing said second part outside of reading phases of said charge storage zone with a second polarization potential;
wherein the first and second polarization potentials are configured so that a potential well in the charge storage zone is deeper when the second polarization potential is applied to the second part of the semiconductor substrate than when the first polarization potential is applied to the second part of the semiconductor substrate.

### Claim 19

A pixel comprising:
a semiconductor substrate;
a photoconversion zone in a first part of a semiconductor substrate;
a charge storage zone in a second part of the semiconductor substrate;
an insulated vertical electrode extending completely through the semiconductor substrate and positioned to electrically and optically insulate the charge storage zone from the photoconversion zone;
a first doped zone in the second part of the semiconductor substrate in contact with said charge storage zone;
a second doped zone in the first part of the semiconductor substrate;
a gate structure over the semiconductor substrate and positioned between the photoconversion zone and said second doped zone; and
an electrical connection between the first doped zone and the second doped zone.

### Claim 20 (depends on 19)

The pixel according to claim 19, wherein said electrical connection is arranged above the semiconductor substrate and extends over the insulated vertical electrode.

### Claim 21 (depends on 19)

The pixel according to claim 19, wherein two portions of the insulated vertical electrode extending parallel to and facing one another delimit the charge storage zone in width, and wherein two other portions of the insulated vertical electrode extending parallel to and facing one another delimit the charge storage zone in length.

### Claim 22 (depends on 19)

The pixel according to claim 19, further comprising:
a doped reading zone in the second part of the semiconductor substrate; and
an additional gate structure resting on a portion of the semiconductor substrate in the second part extending over the semiconductor substrate and positioned between the charge storage zone and the doped reading zone.

### Claim 23 (depends on 19)

The pixel according to claim 19, wherein:
the semiconductor substrate is doped with a first type of conductivity;
the photoconversion zone comprises a layer doped with a second type of conductivity; and
the charge storage zone is doped with the second type of conductivity.

### Claim 24 (depends on 23)

The pixel according to claim 23, wherein the second doped zone is separated from the layer of the photoconversion zone by a channel region over which said gate structure extends.

### Claim 25 (depends on 24)

The pixel according to claim 24, wherein the channel region comprises:
a first doped portion in contact with the second doped zone; and
a second doped portion in contact with the photoconversion zone.

### Claim 26

A pixel comprising:
a semiconductor substrate;
a photoconversion zone in a first part of a semiconductor substrate;
a charge storage zone in a second part of the semiconductor substrate;
an insulated vertical electrode extending completely through the semiconductor substrate and positioned to electrically and optically insulate the charge storage zone from the photoconversion zone; and
a circuit configured:
to apply a first polarization potential to the first part of the semiconductor substrate;
to apply the first polarization potential to the second part of the semiconductor substrate during each reading phase of the charge storage zone; and
to apply a second polarization potential, different from the first polarization potential, to the second part of the semiconductor substrate outside of reading phases of said charge storage zone.