JP2003218344A - Solid state image sensor and its driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid state image sensor and its driving method, in which the generation of a knee component (knee characteristics), i.e., increment in the storage quantity of charges caused by an overflow current, is suppressed without causing any deterioration in sensitivity as an image sensor or deterioration in characteristics, e.g. S/N ratio or dynamic range. <P>SOLUTION: A control electrode 20 for controlling potential at an overflow barrier section 1 is provided and the generation of a knee component at the overflow barrier section 1 is suppressed by controlling the potential of the control electrode 20. The control electrode 20 may be buried in the overflow barrier section 1 or may be arranged to come into electrical contact with the surface of the overflow barrier section 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 sensor and a method for driving the solid-state image sensor.

[0002]

2. Description of the Related Art A solid-state image pickup device (or a functional type also called a charge-coupled image pickup device or a CCD image pickup device) receives light incident from an external subject or the like and responds to the amount of received light. A light-receiving unit (also called a light-receiving region) that generates electric charges, and an overflow barrier unit (also called an overflow barrier region) that determines the saturation signal charge amount that is transferred to the outside of the charge accumulated in the light-receiving unit. There is a so-called overflow drain structure.

A solid-state image pickup device having such a structure is shown in FIG.
As shown in the above example, the P-type overflow barrier portion 1 is, for example, an N-type semiconductor substrate (for example, a silicon wafer).
4 is formed on the Si single crystal portion 4, and a light receiving portion (also referred to as a light receiving region) 2 is formed on the upper layer of the overflow barrier portion 1. A P-type read gate region 3 and a vertical charge transfer region 5 are provided on one side (left side in FIG. 7) of the light receiving unit 2, and a channel stop region is provided on the other side (right side in FIG. 7). 6 is provided.

A transfer electrode 8 is provided on the read gate region 3 and the vertical charge transfer region 5 via an insulating film 7, and an insulating film 7 and a light shielding film 9 are provided on the transfer electrode 8. It is covered. Then, for example, an insulating film / passivation film 10 is formed thereon, and light from an external subject or the like is guided to the light receiving portion 2 to form an image thereon (focusing at a predetermined position). A microlens 11 is formed for this purpose.

In such a solid-state image pickup device, as shown in FIG.
As schematically shown in FIG. 6A, the potential distribution in the depth direction of the semiconductor substrate, the saturation signal charge amount Qs of the light receiving portion 2 is determined by the height of the potential barrier of the P type overflow barrier portion 1. When the amount of light incident on the light receiving unit 2 increases and the accumulated charge amount exceeds the saturation signal charge amount Qs, the excess charge exceeding the excess charge exceeds the potential barrier of the overflow barrier unit 1 (the Si single crystal of the semiconductor substrate 4). Part)).

[0006]

By the way, in the solid-state image pickup device having the above-mentioned structure, even if the accumulated charge amount of the light receiving portion 2 exceeds the saturation signal charge amount Qs and the overflow state occurs, the light receiving amount ( It has a so-called knee characteristic that the amount of accumulated charges increases in response to an increase in the amount of incident light (often in almost proportion). this is,
When the surplus charges flow out over the overflow barrier (the overflow current (Iof) flows), the apparent potential of the overflow barrier section 1 (specifically, the potential of the barrier) becomes higher. This is a phenomenon (characteristic) that occurs due to the occurrence of a knee characteristic (in other words, a knee component that is an increase in the accumulated charge amount due to the knee characteristic) due to the going.

In the solid-state image pickup device having such a knee characteristic, as shown in FIG. 9, an accumulated charge amount corresponding to the maximum light amount in the quality assurance range as a product is 1.8 to the saturated signal charge amount. Since it is 2.0 times, the maximum charge amount (permissible charge amount) that can be handled in the vertical charge transfer region 105 needs to be twice or more the saturation signal charge amount. Therefore, if the area of the entire device is constant,
If the area of the vertical charge transfer region 105 is set to be large, the area that can be used for the other light receiving portions 102 (the area occupied by the light receiving portions 102) is inevitably reduced, and thus the sensitivity as the image pickup device is reduced.

Alternatively, if priority is given to ensuring the sensitivity of such an image pickup device, the area of the vertical charge transfer region 5 cannot be expanded, so that the saturation signal charge amount of 1.8 to 2 as described above is used. Since it is not possible to secure a saturation signal charge amount that is as much as 0.0 times, it is not possible to improve the characteristics such as the S / N ratio of the output and the dynamic range of the image pickup device (in other words, Characteristics deteriorate).

Further, in the case of the solid-state image pickup device set to perform the shutter operation, when the accumulated charge amount reaches 1.8 to 2.0 times the saturation signal charge amount as described above, the shutter is released. The voltage also becomes such a high voltage, which significantly hinders achievement of lowering the voltage of the entire device.

The present invention has been made in view of the above problems, and an object thereof is to reduce the sensitivity as an image pickup device and to reduce S.
Solid-state imaging device and solid-state imaging device capable of suppressing the generation of a knee component (knee characteristic), which is an increase in accumulated charge amount due to an overflow current, without causing deterioration of characteristics such as / N ratio and dynamic range An object is to provide a driving method of an image sensor.

[0011]

A solid-state image pickup device according to the present invention includes a light-receiving portion that receives light and generates an electric charge according to the amount of the received light, and a saturation signal charge amount that is transferred to the outside of the light-receiving portion. A solid-state imaging device, in which a determining overflow barrier portion is provided on a semiconductor substrate, includes a control electrode for controlling the potential of the overflow barrier portion and suppressing the generation of a knee component in the overflow barrier portion. ing.

Another solid-state image sensor according to the present invention is
A solid-state imaging device in which a semiconductor substrate is provided with a light-receiving unit that receives light and generates charges according to the amount of received light, and an overflow barrier unit that determines the amount of saturated signal charges transferred to the outside of the light-receiving unit. The control circuit controls the potential of the semiconductor substrate and suppresses the generation of the knee component in the overflow barrier section.

A method of driving a solid-state image pickup device according to the present invention comprises:
A solid-state imaging device in which a semiconductor substrate is provided with a light-receiving unit that receives light and generates charges according to the amount of received light, and an overflow barrier unit that determines the amount of saturated signal charges transferred to the outside of the light-receiving unit. And a control electrode for controlling the potential of the overflow barrier portion is provided, and the potential of the control electrode is controlled to suppress generation of a knee component in the overflow barrier portion. I'm out.

Further, another solid-state image pickup device driving method according to the present invention includes a light-receiving portion that receives light and generates an electric charge according to the amount of received light, and a saturated signal charge amount transferred to the outside of the light-receiving portion. Is a method of driving a solid-state imaging device provided on a semiconductor substrate, and includes a procedure of controlling the potential of the semiconductor substrate to suppress generation of a knee component in the overflow barrier unit. .

In the solid-state image sensor according to the present invention and the method for driving the solid-state image sensor according to the present invention, a control electrode for controlling the potential of the overflow barrier section is provided,
The potential of the control electrode is controlled to suppress the generation of the knee component in the overflow barrier section.

The control of the potential of the control electrode at this time is performed by applying a predetermined voltage to the control electrode,
It is possible to connect a feedback circuit or the like to the control electrode and feedback control the potential of the control electrode.

The control electrode may be embedded in the overflow barrier portion, or may be provided so as to be in electrical contact with the surface of the overflow barrier portion. In any case, it is desirable that the control electrode be arranged at a position where the potential of the overflow barrier portion can be effectively controlled and the photoelectric conversion action of the light receiving portion is not hindered.

Further, the above-mentioned control electrode is set so that it can also be used as an electrode for performing a shutter operation, and this one control electrode is used for controlling the potential of the overflow barrier portion. It is also possible to separately use the time zone used as the electrode of the above and the time zone used as the electrode for performing the shutter operation in a time sharing manner.

In another solid-state image pickup device according to the present invention and another solid-state image pickup device according to the present invention, the potential of the semiconductor substrate is controlled to suppress the generation of the knee component in the overflow barrier section.

In controlling the potential of the semiconductor substrate at this time, feedback control is performed on the potential of the semiconductor substrate,
The generation of knee components in the overflow barrier section may be suppressed.

The semiconductor substrate is set so that a voltage is actively applied by the voltage applying means, and the voltage applied to the semiconductor substrate by the voltage applying means is the current of the semiconductor substrate as an observed amount. May be used as the control amount, and the feedback control as described above may be performed by changing the control amount corresponding to the observed amount.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment] FIG. 1 is a sectional view showing a schematic configuration of a solid-state image pickup device according to a first embodiment of the present invention. Since the method for driving the solid-state image sensor according to the first embodiment of the present invention is embodied by the operation or action of the solid-state image sensor,
Hereinafter, they will be described together (this also applies to the following second embodiment and the like). Further, in the following description, in order to avoid complication of illustration and description, for example, the active matrix driving method itself of the CCD pixel provided for each pixel in the solid-state image pickup device itself or CC
For the matrix arrangement and wiring of D pixels,
Detailed description and illustration of the general operation and structure of the solid-state image sensor are omitted.

In this solid-state imaging device, a P-type overflow barrier section 1 (also referred to as an overflow barrier region) is formed on a semiconductor substrate 4 such as an N-type Si (silicon) wafer (or a chip obtained by cutting it). The overflow barrier portion 1 is provided on the Si single crystal.
An overflow barrier control electrode (hereinafter, referred to as a control electrode) 20 for controlling the potential of the overflow barrier is embedded in this. Further, a light receiving portion 2 (also referred to as a light receiving region) is formed in a layer above the overflow barrier portion 1.

A P-type read gate region 3 and a vertical charge transfer region 5 are provided side by side in this order on one side (left side in FIG. 1) of the light receiving portion 2, and on the other side (FIG. 1). (Right side)
Is provided with a channel stop region 6. A transfer electrode 8 is provided on the read gate region 3 and the vertical charge transfer region 5 via an insulating film 7, and the transfer electrode 8 is covered with the insulating film 7 and the light shielding film 9. Then, for example, an insulating film / passivation film 10 is formed thereon, and light from an external subject or the like is guided to the light receiving portion 2 to form an image thereon (focusing at a predetermined position). A microlens 11 is formed for this purpose.

As described above, the control electrode 20 is embedded in the overflow barrier portion 1, and the knee component in the overflow barrier portion 1 is controlled by controlling the potential of the overflow barrier portion 1 by the control electrode 20. It is set so that the occurrence of (knee characteristic) can be suppressed.

That is, the control electrode 20 is set so that a predetermined voltage is applied by being connected to, for example, a voltage applying circuit or a power source (not shown), and the control electrode 20 is applied in this manner. Due to this voltage, the potential of the overflow barrier unit 1 can be maintained at a predetermined potential even when the overflow barrier unit 1 is in an overflow state.

Alternatively, a feedback circuit (not shown) may be connected to the control electrode 20 to feedback control the potential of the control electrode 20 when the overflow barrier portion 1 has a potential higher than a predetermined potential that may cause a knee component. Then, even when a light amount such that the overflow barrier portion 1 is in an overflow state is incident, the potential of the overflow barrier portion 1 can be kept at a predetermined potential by the control electrode 20.

The control action of the potential of the overflow barrier section 1 by the control electrode 20 is as schematically shown in FIG. That is, in the conventional general solid-state imaging device, when the amount of light incident on the light receiving unit 2 increases and the accumulated charge amount exceeds the saturation signal charge amount Qs, an overflow current flows, and a broken line curve graph in FIG. As shown, the energy potential of the overflow barrier (specifically, its potential) was further increased, and the knee component (knee characteristic) as shown in FIG. 9 was generated. However, the control electrode 20 of the present embodiment is used. According to the above, the potential of the overflow barrier section 1 is controlled to be kept at a predetermined potential by the control electrode 20, and the energy potential of the overflow barrier does not overflow as shown by the solid curve graph in FIG. Return to the state (or suppress the increase in energy potential)
be able to. As a result, as shown in FIG.
Generation of a knee component (knee characteristic) can be suppressed substantially completely.

The saturation signal charge amount Qs of the light receiving portion 2 in the structure including the control electrode 20 is equal to the control electrode 2
It can be determined by the zero potential. Therefore, it is also possible to perform a so-called shutter operation by sweeping accumulated charges from the overflow barrier using the control electrode 20. By doing so, the overflow barrier can be directly controlled, and this is combined with the effect of suppressing the increase in the energy potential of the overflow barrier by the control electrode 20 as described above, and the conventional general solid-state imaging. The shutter voltage can be made lower than that of the element.

Regarding the method (step) of forming the control electrode 20 so as to be embedded in the overflow barrier section 1, various wirings to be built together in the solid-state image pickup device, photoelectric conversion regions of the light receiving section, etc. Considering the balance (process consistency) with various structures such as
Needless to say, various methods can be adopted, but in any case, the control electrode 20 can effectively control the potential of the overflow barrier section 1, and the photoelectric conversion by the light receiving section 2 is effective. It is desirable to dispose it at a position that does not hinder the conversion action or the action of moving the accumulated charge to the transfer electrode 8.

[Second Embodiment] FIG. 4 is a sectional view showing the schematic arrangement of a solid-state image sensor according to the second embodiment of the present invention.

In the solid-state image sensor according to the second embodiment, the control electrode 21 is not embedded in the semiconductor substrate 4 as in the first embodiment, but is provided beside the light receiving section 2. Surface of overflow barrier part 1 (upper surface in FIG. 4)
It is provided so as to contact with. An overflow drain region 12 is formed adjacent to the overflow barrier portion 1 (on the right side in FIG. 4), and a channel stop region 6 is formed adjacent to the overflow drain region 12 (on the right side in FIG. 4). There is.

With this structure, it is not necessary to add a manufacturing process in which the control electrode 21 is embedded in the overflow barrier section 1 which tends to be relatively complicated, and the overflow barrier section 1 and the overflow drain area are eliminated. Since it is only necessary to form the control electrode 21 on them after forming 12 and the like, there is an advantage that the manufacturing process thereof is simple. However, on the other hand, since the overflow barrier portion 1 and the overflow drain region 12 are arranged side by side in the direction parallel to the surface of the semiconductor substrate 4 (horizontal direction in FIG. 4), the light receiving portion 2 is correspondingly arranged. Effective area is reduced. Therefore, this structure is particularly suitable for a solid-state imaging device having a relatively large cell size. However,
Needless to say, the present invention can be applied to a solid-state imaging device having a small cell size as long as there is no problem of the sensitivity of the light receiving unit 2 being lowered. With such a structure, the first
As in the case of the above embodiment, the generation of the knee component (knee characteristic) can be suppressed substantially completely. Further, also in the solid-state imaging device according to the second embodiment, the control electrode 21 can be used also as an electrode for performing the shutter operation, and by doing so, the conventional general-purpose image sensor can be used. The shutter voltage can be made lower than in the case of such a solid-state image sensor.

[Third Embodiment] FIG. 5 shows a schematic configuration of a solid-state image pickup device according to a third embodiment of the present invention.

In the solid-state image pickup device according to the third embodiment, the light receiving portion 2 that receives light and generates charges according to the amount of received light, and the saturated signal charge transferred to the outside of the light receiving portion 2. Regarding the cross-sectional structure in which the overflow barrier portion 1 that determines the amount is provided in the semiconductor substrate 4,
The semiconductor substrate 4 has the same structure as the solid-state imaging device according to the above-described first and second embodiments, except that the control electrode 20 (or 21) is not provided. It is a characteristic part that the control circuit 30 for controlling the potential of No. 2 to suppress the generation of the knee component in the overflow barrier unit 1 is provided.

More specifically, in the solid-state image pickup device according to the third embodiment, the semiconductor substrate 4 is provided with a voltage application circuit (voltage application means) 31 which is, for example, a combination of a constant voltage power supply and a voltage control circuit. The voltage is set to be actively applied, and the control circuit 30 performs feedback control with respect to the potential of the semiconductor substrate 4 so as to suppress the generation of the knee component in the overflow barrier section 1. Has been done.

More specifically, the control circuit 30 uses, for example, the potential of the semiconductor substrate 4 as a substantially observed amount, and the voltage applied to the semiconductor substrate 4 by the voltage application circuit 31 as a substantially controlled amount, and the observed amount. The feedback control of the potential of the semiconductor substrate 4 is performed by changing the control amount in accordance with.

In the control circuit 30, the substrate current (Isu) due to the overflow current (Iof) caused by the outflow of the excess charge is generated.
b) is detected by the current measuring device 32 as a direct observed amount, and the potential of the overflow barrier portion 1 is substantially set to a knee component (knee characteristic) based on the detected amount of change in the substrate current. The adjustment value of the potential of the semiconductor substrate 4 may be calculated so that it can be suppressed to a potential at which the voltage does not occur, or the potential of the semiconductor substrate 4 is set as a substantial observed amount and the voltage application circuit 31 is used. From the voltage applied to the semiconductor substrate 4 as a substantial control amount, a series of feedback loops of the semiconductor substrate 4 to the control circuit 30 to the voltage application circuit 31 to the semiconductor substrate 4 are configured to output the excess charge in the overflow state. It is also possible to correct the change in the potential of the overflow barrier in the overflow barrier section 1 due to the feedback control by feedback control. It

It goes without saying that various variations can be made to the specific circuit configuration of the control circuit 30 (and the main control method adopted by the control circuit 30). Also, the control method adopted for the feedback control in the control circuit 30 is appropriate from various variations such as a first-order lag system and a second-order lag system in accordance with various aspects of the knee characteristics, for example. It goes without saying that it is desirable to select and use different types. Regarding such a control loop itself, it may be appropriately adopted from among general types,
In any case, the fact that the change in the potential of the overflow barrier due to the outflow of the excess charge in the overflow state is corrected by the feedback control is the outline of the third solid-state imaging device and the driving method thereof according to the present embodiment. This is a characteristic point regarding the configuration.

As schematically shown in FIG. 6, in the conventional general solid-state image pickup device, when the amount of light incident on the light receiving portion 2 increases and the accumulated charge amount exceeds the saturated signal charge amount Qs, the overflow current is increased. Flows, the energy potential (specifically, the potential) of the overflow barrier becomes higher as shown by the broken line curve graph in FIG. 6, and the knee component (knee characteristic) as shown in FIG. 9 occurs. However, according to the solid-state image sensor according to the third embodiment as described above, the feedback control is performed so that the potential in the overflow barrier unit 1 is maintained at a predetermined potential by the control circuit 30, so that one point in FIG. As shown by the chain line curve graph, the energy potential at a position deeper than the light receiving portion 2 of the semiconductor substrate 4 is lowered as a whole, and the overflow barrier It can be corrected in the downward direction (low potential) by feedback control of the distribution curve (or energy potential retract the Nerugi over potential to a state in which overflow does not occur.

At this time, the voltage (absolute value) applied to the semiconductor substrate 4 is increased corresponding to the increase in the energy potential of the overflow barrier, so that the voltage is relatively deeper than the light receiving portion 2 of the semiconductor substrate 4. The energy potential at a position can be lowered overall. As a result, it is possible to substantially completely suppress the generation of the knee component (knee characteristic) as shown in FIG.

The control circuit 30 and the voltage application circuit 31
Needless to say, it may be formed on the semiconductor substrate 4 such as a semiconductor chip, or may be formed separately from the semiconductor substrate 4 and later combined with the semiconductor substrate 4.

[0044]

As described above, according to the first to fourth aspects.
According to the solid-state image sensor according to any one of claims 1 to 8 or the method for driving the solid-state image sensor according to any one of claims 8 to 11, a control electrode for controlling the potential of the overflow barrier unit 1 is provided, By controlling the potential of the overflow barrier section 1 by the potential of the control electrode,
Since the generation of the knee component (knee characteristic) in the overflow barrier section 1 is suppressed, the overflow does not occur without lowering the sensitivity of the image pickup device and deteriorating the characteristics such as the S / N ratio and the dynamic range. It is possible to suppress the generation of the knee component, which is an increase in the accumulated charge amount due to the current.

According to the solid-state image sensor according to any one of claims 5 to 7 or the method for driving the solid-state image sensor according to any one of claims 12 to 14, the potential of the semiconductor substrate is controlled, Since the generation of the knee component in the overflow barrier unit 1 is suppressed, the accumulation caused by the overflow current can be performed without lowering the sensitivity of the image sensor and deteriorating the characteristics such as the S / N ratio and the dynamic range. It is possible to suppress the generation of the knee component, which is an increase in the amount of charge.

In particular, according to the solid-state image pickup device of the fourth aspect or the method of driving the solid-state image pickup device of the eleventh aspect, the control electrode is also used as the control electrode for performing the shutter operation. Therefore, both the control of the generation of the knee component, which is the increase in the accumulated charge amount due to the overflow current, and the shutter operation are realized by one control electrode without complicating the structure. It becomes possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of a solid-state image pickup device according to a first embodiment of the present invention.

FIG. 2 is a diagram schematically showing the control action of the potential of the overflow barrier section by the control electrode.

FIG. 3 is a diagram schematically showing the effect of substantially completely suppressing the generation of a knee component (knee characteristic) by the solid-state imaging device and the driving method thereof according to each embodiment of the present invention.

FIG. 4 is a sectional view showing a schematic configuration of a solid-state image sensor according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a schematic configuration of a solid-state imaging device according to a third embodiment of the present invention.

FIG. 6 is a diagram schematically showing the control action of the potential of the overflow barrier section by the control circuit.

FIG. 7 is a cross-sectional view showing an example of a schematic configuration of a conventional solid-state imaging device having an overflow drain structure.

FIG. 8 is a diagram schematically showing a potential distribution in the depth direction of a semiconductor substrate.

FIG. 9 is a diagram showing a knee component in a solid-state imaging device and a driving method thereof.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Overflow barrier part, 2 ... Light receiving part, 4 ... Semiconductor substrate, 20, 21 ... Control electrode, 30 ... Control circuit, 31
... Voltage application circuit

Claims (14)

[Claims] 1. A semiconductor substrate is provided with a light-receiving portion that receives light and generates charges according to the amount of received light, and an overflow barrier portion that determines the amount of saturated signal charge transferred to the outside of the light-receiving portion. The solid-state imaging device according to claim 1, further comprising a control electrode for controlling the potential of the overflow barrier part and suppressing the generation of a knee component in the overflow barrier part. 2. The control electrode is embedded in the overflow barrier portion.
The solid-state image sensor according to claim 1. 3. The solid-state image pickup device according to claim 1, wherein the control electrode is provided so as to be in electrical contact with the surface of the overflow barrier portion. 4. The solid-state image pickup device according to claim 1, wherein the control electrode is set so as to also serve as a control electrode for performing a shutter operation. 5. A semiconductor substrate is provided with a light-receiving portion that receives light and generates electric charges according to the amount of received light, and an overflow barrier portion that determines the amount of saturated signal charge transferred to the outside of the light-receiving portion. A solid-state image sensor, comprising: a control circuit that controls the potential of the semiconductor substrate to suppress the generation of a knee component in the overflow barrier section. 6. The solid according to claim 5, wherein the control circuit performs feedback control on the potential of the semiconductor substrate to suppress generation of a knee component in the overflow barrier section. Image sensor. 7. The semiconductor substrate is set so that a voltage is actively applied by a voltage applying means, and the control circuit sets the potential of the semiconductor substrate as an observed amount,
The feedback control is performed by using a voltage applied to the semiconductor substrate by the voltage applying unit as a control amount and changing the control amount corresponding to the observed amount. 6. The solid-state image sensor according to 6. 8. A semiconductor substrate is provided with a light-receiving portion that receives light and generates electric charges according to the amount of received light, and an overflow barrier portion that determines the amount of saturated signal charge transferred to the outside of the light-receiving portion. In the method for driving a solid-state imaging device, a control electrode for controlling the potential of the overflow barrier section is provided, and the potential of the control electrode is controlled to control the knee component of the overflow barrier section. A method for driving a solid-state imaging device, the method including a step of suppressing the generation. 9. The method for driving a solid-state image pickup device according to claim 8, wherein the control electrode is embedded in the overflow barrier portion. 10. The method for driving a solid-state image pickup device according to claim 8, wherein the control electrode is provided so as to be in electrical contact with the surface of the overflow barrier portion. 11. The method for driving a solid-state image sensor according to claim 8, wherein the control electrode is also used as a control electrode for performing a shutter operation. 12. A semiconductor substrate is provided with a light-receiving portion that receives light and generates an electric charge according to the amount of received light, and an overflow barrier portion that determines the amount of saturated signal charge transferred to the outside of the light-receiving portion. A method of driving a solid-state image sensor, comprising: controlling the potential of the semiconductor substrate to suppress the generation of a knee component in the overflow barrier section. 13. The method of driving a solid-state imaging device according to claim 12, wherein feedback control is performed on the potential of the semiconductor substrate to suppress the generation of a knee component in the overflow barrier section. 14. The semiconductor substrate is set so that a voltage is actively applied by a voltage applying unit, and the potential of the semiconductor substrate is used as an observation amount, and the voltage is applied to the semiconductor substrate by the voltage applying unit. 14. The method for driving a solid-state imaging device according to claim 13, wherein the feedback control is performed by using a voltage as a control amount and changing the control amount in accordance with the observed amount.