# US 8,785,834 B2 · Solid-state image sensor, control method for the same, and electronic device

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- Number: US 8,785,834 B2
- Document ID: US8785834B2
- Status: Granted
- Kind: B2
- Application number: 13/961,616
- Filed: 2013-08-07
- Published: 2014-03-20
- Granted: 2014-07-22
- Earliest claimed: 2012-09-14
- Assignees: Sony Corporation
- Applicants: Sony Corporation
- Inventors: Yorito Sakano
- Web page: https://patentgrep.com/patent/US8785834B2

## CPC

- H10F 39/80373: {characterised by the gate of the transistor}
- H04N 25/59: by controlling the amount of charge storable in the pixel, e.g. modification of the charge conversion ratio of the floating node capacitance
- H04N 25/771: comprising storage means other than floating diffusion
- 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
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

There is provided a solid-state image sensor including a plurality of unit pixels each including a photoelectric transducer generating a charge corresponding to an amount of incident light and accumulating the charge therein, a first transfer gate transferring the charge accumulated in the photoelectric transducer, a charge holding region where the charge is held, a second transfer gate transferring the charge, a floating diffusion region where the charge is held to be read out as a signal, a charge discharging gate transferring the charge to a charge discharging part, and a structure including an overflow path formed in a boundary portion between the photoelectric transducer and the charge holding region.

## Claims

### Claim 1

A solid-state image sensor comprising:
a plurality of unit pixels each including
a photoelectric transducer which generates a charge corresponding to an amount of incident light and accumulates the charge therein,
a first transfer gate which transfers the charge accumulated in the photoelectric transducer,
a charge holding region in which the charge transferred from the photoelectric transducer by the first transfer gate is held,
a second transfer gate which transfers the charge held in the charge holding region,
a floating diffusion region in which the charge transferred from the charge holding region by the second transfer gate is held to be read out as a signal,
a charge discharging gate which transfers the charge received from the photoelectric transducer, to a charge discharging part, and
a structure including an overflow path formed in a boundary portion between the photoelectric transducer and the charge holding region, the overflow path being formed at a potential for determining a predetermined charge amount and transferring a charge exceeding the predetermined charge amount as a signal charge from the photoelectric transducer to the charge holding region,
wherein as a channel electric-potential of the charge discharging gate, an electric-potential lower than an electric-potential of the overflow path is set, or an electric-potential higher than the electric-potential of the overflow path and lower than an electric-potential causing the photoelectric transducer to be completely depleted is set.

### Claim 2 (depends on 1)

The solid-state image sensor according to claim 1,
wherein when an intermediate electric-potential is applied to the charge discharging gate as a gate electric-potential, the channel electric-potential is set at a predetermined electric-potential.

### Claim 3 (depends on 1)

The solid-state image sensor according to claim 1,
wherein when an electric-potential of a drain of the charge discharging part is driven, the channel electric-potential is set at a predetermined electric-potential.

### Claim 4 (depends on 3)

The solid-state image sensor according to claim 3,
wherein a channel of the charge discharging gate is formed in a region deeper in a direction to a substrate than a silicon surface.

### Claim 5 (depends on 1)

The solid-state image sensor according to claim 1,
wherein an off-state voltage of each of the charge discharging gate, the first transfer gate, and the second transfer gate is a negative voltage.

### Claim 6

A control method for a solid-state image sensor, the solid-state image sensor including
a plurality of unit pixels each including
a photoelectric transducer which generates a charge corresponding to an amount of incident light and accumulates the charge therein,
a first transfer gate which transfers the charge accumulated in the photoelectric transducer,
a charge holding region in which the charge transferred from the photoelectric transducer by the first transfer gate is held,
a second transfer gate which transfers the charge held in the charge holding region,
a floating diffusion region in which the charge transferred from the charge holding region by the second transfer gate is held to be read out as a signal,
a charge discharging gate which transfers the charge received from the photoelectric transducer, to a charge discharging part, and
a structure including an overflow path formed in a boundary portion between the photoelectric transducer and the charge holding region, the overflow path being formed at a potential for determining a predetermined charge amount and transferring a charge exceeding the predetermined charge amount as a signal charge from the photoelectric transducer to the charge holding region,
the method comprising:
as a channel electric-potential of the charge discharging gate, setting an electric-potential lower than an electric-potential of the overflow path, or setting an electric-potential higher than the electric-potential of the overflow path and lower than an electric-potential causing the photoelectric transducer to be completely depleted.

### Claim 7

An electronic device having a solid-state image sensor mounted thereon, the solid-state image sensor including
a plurality of unit pixels each including
a photoelectric transducer which generates a charge corresponding to an amount of incident light and accumulates the charge therein,
a first transfer gate which transfers the charge accumulated in the photoelectric transducer,
a charge holding region in which the charge transferred from the photoelectric transducer by the first transfer gate is held,
a second transfer gate which transfers the charge held in the charge holding region,
a floating diffusion region in which the charge transferred from the charge holding region by the second transfer gate is held to be read out as a signal,
a charge discharging gate which transfers the charge received from the photoelectric transducer, to a charge discharging part, and
a structure including an overflow path formed in a boundary portion between the photoelectric transducer and the charge holding region, the overflow path being formed at a potential for determining a predetermined charge amount and transferring a charge exceeding the predetermined charge amount as a signal charge from the photoelectric transducer to the charge holding region,
wherein as a channel electric-potential of the charge discharging gate, an electric-potential lower than an electric-potential of the overflow path is set, or an electric-potential higher than the electric-potential of the overflow path and lower than an electric-potential causing the photoelectric transducer to be completely depleted is set.