JP2003174156A - Solid-state imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging device which has dark output nonuniformity improved. <P>SOLUTION: The device is constituted by providing a drain area 3, which stops excited electric charges from entering a photodetection part 1 from a peripheral circuit 2, in the space between the peripheral circuit 2 and photodetection part 1. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device used for an image sensor for reading an image, a camera and the like, and more particularly to a solid-state image pickup device with improved non-uniformity in dark output.

[0002]

2. Description of the Related Art In recent years, solid-state image pickup devices using CCDs have
Because of its small size, light weight, and high performance, it is widely used in image sensors for reading images, video cameras, and the like. Among the solid-state image pickup devices using a CCD, the basic structure of the interline transfer type solid-state image pickup device has a light receiving part (pixel) for accumulating signal charges obtained by photoelectrically converting incident light by a photodiode or the like, and a transfer Gate (storage electrode)
Via the CCD, the vertical CCD transfer unit that receives the signal charge accumulated in the light receiving unit and transfers the signal charge in the vertical direction and the signal charge of one line transferred by the vertical CCD transfer unit in the horizontal direction Horizontal CCD transfer unit, transfer gate,
A drive control circuit for driving and controlling the vertical CCD transfer unit and the horizontal CCD transfer unit, and an output circuit for outputting the signal charges transferred by the horizontal CCD transfer unit to the outside are provided.

In such a structure, when the drive control circuit and the output circuit, which are peripheral circuits arranged around the core section, operate with respect to the core section including the light receiving section, the transfer gate and the transfer section, the operation is performed. Along with this, excitation charges are generated from the transistors such as MOSFETs that constitute the peripheral circuit. As shown in FIG. 5 (A) and FIG. 5 (B) (a cross-sectional view taken along the line AA in FIG. 5 (A)), the excitation charge is generated in the N-type light receiving portion (pixel) 51 and its periphery. Circuit 52
It was easy for the peripheral circuit 52 to enter the light receiving portion 51 through the P-type well region 53 in which the holes were formed. For this reason, even when the incident light is not applied to the light receiving section 51, the excitation charge has accumulated in the light receiving section 51 into which the excitation charges have entered, and the accumulated charges have been read out to the outside. Therefore, although the incident light is not applied to the light receiving unit 51 (in the dark time), an output is generated depending on the light receiving unit 51, which is one of the characteristics of the solid-state imaging device, and the dark-time output nonuniformity. (DSNU) was deteriorating.

[0004]

As described above,
In the conventional solid-state imaging device, the peripheral circuits arranged around the core unit including the light receiving unit, the transfer gate, and the transfer unit operate, so that the excitation charges generated in the transistors forming the peripheral circuit are transferred to the light receiving unit. It was easy to break in. As a result, even in a dark time when the incident light is not applied to the light receiving portion, the light receiving portion accumulates and outputs the electric charge, which causes a problem that the characteristic of the output nonuniformity in the dark is deteriorated. I was invited.

Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a solid-state image pickup device with improved non-uniformity in dark output.

[0006]

Means for Solving the Problems In order to achieve the above object, means for solving the problems are as follows: a light receiving section for accumulating signal charges obtained by photoelectrically converting incident light, and a light receiving section via a transfer gate. A signal charge accumulated in the transfer section, the transfer section transferring the signal charge, the transfer gate, a drive control circuit driving and controlling the transfer section, and outputting the signal charge transferred by the transfer section to the outside. And an excitation charge generated in the peripheral circuit, which is provided at least between the output circuit, the core unit including the light receiving unit, the transfer gate, and the transfer unit, and the peripheral circuit including the drive control circuit and the output circuit. And a drain region that blocks the excitation charges from entering the light receiving portion.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a solid-state image pickup device according to an embodiment of the present invention. FIG. 1A is a plan view and FIG. 1B is a line AA in FIG. It is sectional drawing along. In FIG. 1, the solid-state imaging device according to the present embodiment shows a light receiving portion (pixel) 1 for accumulating signal charges obtained by photoelectrically converting incident light, and a signal charge accumulated in the light receiving portion 1 via a transfer gate. A core unit including a transfer unit configured to receive and transfer the signal charge, for example, a CCD shift register, a transfer gate, a drive control circuit for driving and controlling the transfer unit, and the signal charge transferred by the transfer unit to the outside And a drain region 3.

When the solid-state image pickup device is formed on an N-type semiconductor substrate, the drain region 3 forms an N-type light receiving region formed on a P-type well region 4 formed on the N-type semiconductor substrate. P-type impurities are formed in the P-type well region 4 by implanting P-type well regions 4 into the transistors, such as MOSFET, that form the portion 1 and the peripheral circuit 2. The drain region 3 is provided at least between the core portion and the peripheral circuit 2, and is arranged and formed, for example, as shown in FIGS. In the embodiment shown in FIG. 2, the drain region 3 is arranged and formed so as to surround the periphery of the core portion 7 with respect to the peripheral circuits including the drive control circuit 5 and the output circuit 6. In the embodiment shown in FIG. 3, the drain region 3 includes a region between the core unit 7 and the drive control circuit 5 where the core unit 7 and the drive control circuit 5 face each other, and the core unit 7.
And the output circuit 6 are arranged and formed in a region between the core portion 7 and the output circuit 6 facing each other. In the embodiment shown in FIG. 4, the drain region 3 is driven except for the core portion 7 and the drive control circuit 5 and the output circuit 6 where the core portion 7 and the drive control circuit 5 and the output circuit 6 do not face each other. The control circuit 5 and the output circuit 6 are arranged and formed so as to surround part of them.

As described above, the drain region 3 formed between the core portion 7 and the peripheral circuit 2 is applied with a potential at least higher than the potential potential of the light receiving portion 1, preferably the potential potential of the light receiving portion 1. 2 times or more, and generally a high power supply potential is applied.

In such a structure, when the excitation charge is generated by the operation of the transistor of the peripheral circuit, the excitation charge, which is generated from the peripheral circuit 2 toward the light receiving section 1 through the well region 4, among the generated excitation charges. The charges are trapped and absorbed in the drain region 3.

As a result, the excitation charges are blocked and prevented from entering the light receiving portion 1, and the excitation charges are prevented from being accumulated in the light receiving portion 1 in the dark. As a result, the dark output nonuniformity (DSNU) characteristic can be improved.

The solid-state image pickup device of such an embodiment can be implemented with a line sensor or area sensor, and similar effects can be obtained. Also,
For example, a CCD shift register that constitutes a transfer unit that transfers signal charges includes a shift register that transfers signal charges accumulated in pixels in odd columns and a shift register that transfers signal charges accumulated in pixels in even columns. Even in the case where the shift register is composed of two columns, it can be carried out in the same manner as the above-mentioned embodiment, and the same effect can be obtained.

[0014]

As described above, according to the present invention, since the drain region for blocking the excitation charge that tries to enter the light receiving portion from the peripheral circuit is provided, the excitation charge is accumulated in the light receiving portion in the dark. Can be prevented and the characteristics of dark output non-uniformity (DSNU) can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a solid-state imaging device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement example of drain regions.

FIG. 3 is a diagram showing another arrangement example of drain regions.

FIG. 4 is a diagram showing another arrangement example of drain regions.

FIG. 5 is a diagram showing a configuration of a conventional solid-state imaging device.

[Explanation of symbols]

1 Light receiving part 2 peripheral circuits 3 drain region 4 P well 5 Drive control circuit 6 Output circuit 7 core part

Claims (4)

[Claims] 1. A light receiving section for accumulating signal charges obtained by photoelectrically converting incident light, and a transfer section for receiving the signal charges accumulated in the light receiving section via a transfer gate and transferring the signal charges. A drive control circuit that drives and controls the transfer gate and the transfer unit; an output circuit that outputs the signal charges transferred by the transfer unit to the outside; and a core that includes the light receiving unit, the transfer gate, and the transfer unit. A drain region that is provided at least between a drive circuit and a peripheral circuit including the drive control circuit and the output circuit, captures the excitation charge generated in the peripheral circuit, and blocks the intrusion of the excitation charge into the light receiving unit. And a solid-state image pickup device. 2. The solid-state imaging device according to claim 1, wherein the drain region is arranged and formed so as to surround the core portion. 3. The solid-state imaging device according to claim 1, wherein the drain region is arranged and formed in a region where the core portion and the peripheral circuit face each other. 4. The solid-state imaging device according to claim 1, wherein the drain region is arranged and formed around a part of the peripheral circuit including a region where the core portion and the peripheral circuit face each other. .