JP2002158925A - Solid-state image pickup device and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To thin out pixels horizontally in a solid-state image pickup device with a shunt structure. SOLUTION: This solid state image pickup device has a plurality of light receiving regions 11 arranged two-dimensionally into a matrix form, transfer electrodes 3 and 4 which transfer signal charge in the vertical direction of the two-dimensional arrangement, and shunt wirings 2 extended between the respective light receiving regions 11 in the charge transfer direction. There are provided unconnected parts 5 which cut off electrical connections in the horizontal directions of the transfer electrodes 3 and 4 extending horizontally in the two-dimensional arrangement between the respective light receiving regions 11. Unit shunt wiring groups are obtained by the unconnected parts 5 separating the groups. A driving mode is switched between a mode that a drive signal is supplied to one unit shunt wiring group and a mode that a drive signal is not supplied to the unit shunt wiring group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a solid-state image pickup device having a shunt structure, that is, a shunt wiring, and a driving method thereof.

[0002]

2. Description of the Related Art Some solid-state imaging devices used as imaging devices have an auxiliary wiring for preventing propagation delay, that is, a shunt wiring. For example, a CCD solid-state image pickup having an FIT structure having an image pickup size of 2/3 type or larger, a frame rate of, for example, the HD / SD standard (1/30 second, 1/60 second), and a high-speed frame shift operation. The device employs a shunt structure in order to suppress the propagation delay of the vertical transfer clock pulse.

Conventionally, a CCD solid-state image pickup device having a shunt structure, as shown in FIG. 3, for example, transfers an image pickup area 10 for performing photoelectric conversion on a pixel basis and a signal charge read from the image pickup area 10 in a horizontal direction. Horizontal transfer register 2
In addition to 0, a shunt bus line 31 and a shunt wiring 32 are provided. The shunt bus line 31 is located on the opposite side of the horizontal transfer register 20 with respect to the imaging area 10, and the shunt wiring 32 is provided between the pixel rows of the imaging area 10 with respect to the imaging area 10. Have been.

In the CCD solid-state image pickup device having such a shunt structure, the image pickup area 10 is constituted, for example, as shown in FIG. That is, in the imaging area 10,
A plurality of light receiving regions 11 are two-dimensionally arranged in a matrix on the front surface side of the substrate of the CCD solid-state imaging device.

A first transfer electrode 1 made of, for example, polysilicon (Poly-Si) for transferring charges in a two-dimensional array in a vertical direction (the direction of arrow a in the figure) is provided between each light receiving region 11.
Second and second transfer electrodes 13 are provided. Each of the first transfer electrode 12 and the second transfer electrode 13 extends in a two-dimensional array horizontal direction (a direction orthogonal to the charge transfer direction a) between the respective light receiving regions 11, and each extends between the light receiving regions 11. It is arranged alternately every time. Then, between the respective rows of the light receiving regions 11 along the charge transfer direction a, the respective ends are stacked via an insulating film.

A buffer film 14 made of, for example, Poly-Si is provided between the columns of the light receiving region 11 on the first transfer electrode 12 and the second transfer electrode 13 via an insulating film. Shunt wirings 32 made of a material having a low resistance, such as aluminum (Al) or tungsten (W), are provided through the film so as to extend along the charge transfer direction a. The shunt wiring 32 is disposed with an insulating film interposed between the first transfer electrode 12 and the second transfer electrode 13. Each is electrically connected to the first transfer electrode 12 or the second transfer electrode 13. That is, the shunt wiring 32 is wired to the first transfer electrode 12 or the second transfer electrode 13 via the contact portion 15.

Although not shown, in the upper layer of the shunt wiring 32, only the light receiving region 11 is opened.
Al or W for shading is formed.

In the CCD solid-state image pickup device thus constructed, when a vertical transfer clock pulse, for example, V1 to V4 in the case of four-phase driving, is applied to each shunt wiring 32 through the shunt bus line 31, the pulse V1 to V4 is applied. Is applied to the first transfer electrode 12 or the second transfer electrode 13 via the shunt wiring 32 and the contact portion 15, whereby the signal charges accumulated in each light receiving region 11 are transferred between the columns of the light receiving region 11. It will be transferred in the direction a. In other words, since the vertical transfer clock pulse is supplied from the shunt wiring 32 provided between each column of the light receiving region 11, the number of the light receiving regions 11 forming the imaging area 10 is large, and the first transfer electrode 12 and the second transfer Even when the electrode 13 becomes longer in the horizontal direction, the propagation delay of the vertical transfer clock pulse does not occur. The signal charges read from the imaging area 10 in this manner are subsequently transferred by the horizontal transfer register 20 in the horizontal direction (the direction of the arrow b in FIG. 3).

[0009]

By the way, in recent years, CC
The D solid-state imaging device is required to support a large number of pixels (for example, 10 million pixels) and a large imaging size (for example, 35 mm size). However, in order to meet these requirements, if all the signal charges obtained in each light receiving region 11 are to be taken out from the horizontal transfer register 20, that is, from one output, a horizontal transfer clock pulse of a very high frequency is required. Would.

For this reason, in the CCD solid-state imaging device, for example, a monitoring mode for merely confirming a captured image in order to suppress a rise in the frequency of a clock pulse for transferring signal charges (hereinafter referred to as “driving frequency”) as much as possible. When it is not necessary to read out the signal charges from all the light receiving regions 11 as in the case of time, it is generally performed to read out the pixels by thinning them out.

However, the conventional shunt structure CC
In the D solid-state imaging device, thinning of pixels arranged in the vertical direction can be performed by controlling the vertical transfer clock pulse.
In addition, since the second transfer electrode 13 is an electrode that extends and is connected horizontally, thinning out of pixels arranged in a horizontal direction cannot be performed in principle. Therefore, for example, even in the monitoring mode, the driving frequency in the horizontal direction cannot always be sufficiently suppressed.

In view of the above, the present invention provides a shunt-structure solid-state imaging device that can also perform thinning of pixels in the horizontal direction, and is particularly applicable to a case where the number of pixels is increased or the imaging size is increased. It is an object of the present invention to provide a suitable solid-state imaging device and a driving method thereof.

[0013]

The present invention is a solid-state imaging device devised to achieve the above object. That is,
A plurality of light receiving regions arranged two-dimensionally in a matrix,
A transfer electrode for transferring the charge accumulated in each light receiving region in the vertical direction of the two-dimensional array, and a transfer electrode disposed between the light receiving regions so as to extend along the transfer direction of the charge by the transfer electrode. In a solid-state imaging device including a shunt wiring and a contact portion that electrically connects the transfer electrode and the shunt wiring, the transfer electrode extending in the horizontal direction of the two-dimensional array between light receiving regions. It is characterized in that a non-connection portion for cutting off the electrical connection in the horizontal direction is provided.

Further, the present invention is a method for driving a solid-state imaging device devised to achieve the above object. That is,
A plurality of light receiving regions arranged two-dimensionally in a matrix,
A transfer electrode for transferring the charge accumulated in each light receiving region in the vertical direction of the two-dimensional array, and a transfer electrode disposed between the light receiving regions so as to extend along the transfer direction of the charge by the transfer electrode. A method for driving a solid-state imaging device comprising a shunt wiring and a contact portion for electrically connecting the transfer electrode and the shunt wiring, wherein the two-dimensional array extends in a horizontal direction between light receiving regions. A non-connection portion is provided to disconnect the electrical connection of the transfer electrode in the horizontal direction for each shunt wiring corresponding to an integral multiple of the number of phases of the drive signal applied to the transfer electrode, For each shunt wiring lined up in the horizontal direction of the array, whether or not to apply the drive signal is switched for each shunt wiring group which is one unit due to disconnection of the non-connection portion.

According to the solid-state image pickup device having the above configuration and the method for driving the solid-state image pickup device according to the above procedure, even if the transfer electrode extends in the horizontal direction, the electrical connection in the horizontal direction is cut off by the non-connection portion. . Therefore, even if a drive signal is given to a certain shunt wiring, unless a drive signal is given to a shunt wiring adjacent to the shunt wiring with a non-connection portion interposed therebetween, charges are read only from the row of the light receiving region corresponding to the shunt wiring. No charge is read out from the row of the light receiving region corresponding to the shunt wiring adjacent to the shunt wiring. That is, thinning can be performed on a plurality of light receiving regions arranged two-dimensionally in a matrix for each column of the light receiving regions disconnected by the non-connection portion.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a solid-state imaging device according to the present invention and a driving method thereof will be described with reference to the drawings. FIG. 1 is a plan view illustrating a main part of an example of a solid-state imaging device according to the present invention, and FIG. 2 is a plan view illustrating a schematic configuration of an example of the solid-state imaging device according to the present invention. In the drawings, components that are substantially the same as those of the related art (see FIGS. 3 and 4) are given the same reference numerals, and detailed descriptions thereof will be omitted.

As shown in FIG. 2, the CCD solid-state imaging device described in the present embodiment also has a shunt bus line 1 and a shunt wiring line in addition to an imaging area 10 and a horizontal transfer register 20, in substantially the same manner as the conventional one. 2 is provided.

However, the shunt bus line 1 differs from the conventional one in the following points. Conventionally, if the vertical transfer is, for example, four-phase drive, it has four pads (electrodes) and four bus lines corresponding to V1 to V4, and V1 and V2 between each pixel column of the imaging area 10. , V3, V4,.
On the other hand, in the shunt bus line 1 described in the present embodiment, V1 is set to V1A and V1B, and V3 is set to V3A and V3B.
And has six pads (electrodes) and six bus lines corresponding to them, respectively, and the shunt wiring 2 extending to the imaging area 10 is also V1A, V2, V3A, V4, V
1B, V2, V3B, V4,...

Also, as shown in FIG.
Also, in substantially the same manner as in the prior art, a plurality of light receiving areas 11 and a first transfer electrode 3 and a second transfer electrode 4 arranged between the light receiving areas 11 are provided on the surface side of the substrate of the CCD solid-state imaging device. ,
The shunt wiring 2 is provided with a buffer film 14 and shunt wirings 2 arranged along the charge transfer direction, and a contact portion 15 appropriately provided for each shunt wiring 2.

However, the first transfer electrode 3 and the second transfer electrode 4 are different from the conventional one in the following points. That is, each of the first transfer electrode 3 and the second transfer electrode 4 extends in the horizontal direction of the two-dimensional array between the respective light receiving regions 11 in substantially the same manner as the conventional one. Non-connection portions 5 for disconnecting the electrical connection in the horizontal direction are provided at a plurality of locations described later.

The non-connection portion 5 is made of, for example, an insulating film. The non-connection portion 5 is formed on the substrate by making the mask pattern for forming the first transfer electrode 3 and the second transfer electrode 4 different from the conventional one. Things. This non-connection part 5
Does not require a special step (process) for its formation, and thus can be easily formed.

The non-connection portions 5 are arranged between the adjacent shunt wirings 2. When a plurality of non-connection portions 5 are provided in the horizontal direction, a predetermined number of the non-connection portions 5 are arranged between the non-connection portions 5 arranged in the horizontal direction. Are arranged such that the shunt wirings 2 exist. Here, the predetermined number is a number corresponding to an integral multiple of the number of phases of the vertical transfer clock pulse applied to the first transfer electrode 3 and the second transfer electrode 4. For example, in the case of four-phase drive, four (four-phase × one) shunt wires 2 corresponding to V1A, V2, V3A, and V4 exist between the non-connection portions 5 as shown in the figure. Shall be. That is, the non-connection portions 5 are provided for each shunt wiring 2 in a number corresponding to an integral multiple of the number of phases of the vertical transfer clock pulse in the horizontal direction of the two-dimensional array.

Therefore, in the imaging area 10, if a group of shunt wirings (four shunt wirings 2 in the illustrated example) sandwiched between the non-connection portions 5 is one unit, a certain unit is V
1A, V2, V3A, and V4, each of which includes four shunt wirings 2 adjacent to each other across the non-connection portion 5, and four shunt wirings corresponding to V1B, V2, V3B, and V4. The arrangement that the wiring 2 is included is repeated in the horizontal direction of the two-dimensional array.

In the CCD solid-state image pickup device thus configured, each shunt wiring 2 is connected through the shunt bus line 1.
Is applied to the first transfer electrode 3 or the second transfer electrode 4 via the shunt wiring 2 and the contact portion 15, the pulse is accumulated in each light receiving region 11. The signal charges are transferred in the charge transfer direction a between the columns of the light receiving region 11. Then, the signal charges read from the imaging area 10 are transferred by the horizontal transfer register 20 in the horizontal direction (the direction of the arrow b in FIG. 2).

At this time, if the vertical transfer clock pulse applied to the shunt bus line 1 is controlled in the same manner as in the prior art, it is possible to perform 1/2 thinning of the pixels arranged in the vertical direction. Note that this vertical thinning is completely the same as the conventional one, and thus a detailed description thereof is omitted here.

The shunt bus line 1 to which the vertical transfer clock pulse is applied changes V1 to V1A and V1B.
In addition, V3 is divided into V3A and V3B, and has six pads and six bus lines corresponding to each. Therefore, when a vertical transfer clock pulse is applied to the shunt bus line 1, for example, V1A and V3A
Is given the pulse (charge reading pulse), and V1B
And V3B are not given the pulse,
In the CCD solid-state imaging device according to the present embodiment, it is possible to perform の 間 thinning of pixels in the horizontal direction in addition to 間 thinning of pixels in the vertical direction.

More specifically, if a vertical transfer clock pulse to which a read pulse is applied is applied to V1A and V3A, V1A, V2, V3A, and V4 constituting one unit are provided.
, The vertical transfer clock pulse is applied to the four shunt wiring groups, so that signal charges are read out from the respective light receiving regions 11 corresponding to the shunt wiring groups, and the signal charges are directed to the horizontal transfer register 20. Will be transferred vertically. However, by applying a vertical transfer clock pulse to which no read pulse is applied to V1B and V3B, the shunt wirings corresponding to V1B and V3B for one unit described above and other units adjacent to each other across the non-connection portion 5 are provided. 2 does not transmit the read clock pulse, so that signal charges to the horizontal transfer register 20 are not read and transferred from each light receiving region 11 corresponding to the shunt wiring group constituting the unit.

That is, whether or not a vertical transfer clock pulse is applied is switched for each unit (shunt wiring group) divided by the non-connection portion 5, and any one of the units adjacent to each other with the non-connection portion 5 interposed therebetween is selected. By giving a vertical transfer clock pulse to which only one of the readout pulses is applied, in the CCD solid-state imaging device of the present embodiment, it is possible to perform １ ／ thinning of pixels in the horizontal direction.

On the other hand, V1A and V1B, V3A and V3B
In the case where the same pulse is applied, the signal charges are read out and transferred from all the light receiving areas 11 constituting the imaging area 10, and the same operation as in the conventional case where normal thinning is not performed is enabled.

As described above, according to the CCD solid-state imaging device and the driving method of the present embodiment, the horizontal connection of the first transfer electrode 3 and the second transfer electrode 4 is disconnected by the non-connection portion 5. By doing so, it is possible to perform pixel thinning in the horizontal direction even in a shunt structure. Therefore, for example, when it is not necessary to read out signal charges from all the light receiving regions 11 as in the monitoring mode,
By performing pixel thinning in the horizontal direction, it is possible to suppress the driving frequency in the horizontal direction, and it is possible to avoid as much as possible the adverse effects (such as the influence of noise and a rise in device temperature) due to the increase in the driving frequency. This is suitable for use in cases such as a large imaging size.

In the present embodiment, the case where the transfer in the vertical direction is four-phase drive and the non-connection portion 5 is provided for every four (four-phase × one-time) shunt wirings 2 will be described as an example. However, the present invention is not limited to this. For example, even when signal charges are transferred by two-phase driving,
It is conceivable to apply it in exactly the same way. Also, the number of shunt wires 2 constituting one unit may be an integral multiple of the number of drive phases, such as eight, twelve, etc. in the case of four-phase drive. However, if the number of shunt wirings 2 is made equal to the number of driving phases (the number of phases × 1), the pitch at the time of performing pixel thinning in the horizontal direction can be made the finest. It is possible to minimize discomfort to the image).

In the present embodiment, the solid-state imaging device having the two-layer structure of the first transfer electrode 3 and the second transfer electrode 4 has been described as an example. It is conceivable to apply.

[0033]

As described above, according to the solid-state imaging device and the method of driving the same according to the present invention, it is possible to thin out pixels in the horizontal direction even in a shunt structure. Can be suppressed,
In particular, it is suitable for use in responding to an increase in the number of pixels and a large imaging size.

[Brief description of the drawings]

FIG. 1 is a plan view showing a main part of an example of a solid-state imaging device according to the present invention.

FIG. 2 is a plan view illustrating a schematic configuration of an example of a solid-state imaging device according to the present invention.

FIG. 3 is a plan view illustrating a schematic configuration of an example of a conventional solid-state imaging device.

FIG. 4 is a plan view showing a main part of an example of a conventional solid-state imaging device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Shunt bus line, 2 ... Shunt wiring, 3 ... First transfer electrode, 4 ... Second transfer electrode, 5 ... Non-connection part, 10 ... Imaging area, 11 ... Light receiving area, 15 ... Contact part

Claims (3)

[Claims] A plurality of light receiving regions arranged two-dimensionally in a matrix; a transfer electrode for transferring charges accumulated in each light receiving region in a vertical direction of the two-dimensional array; A solid-state imaging device comprising: a shunt wiring disposed so as to extend along a transfer direction of charges by the transfer electrode; and a contact portion for electrically connecting the transfer electrode and the shunt wiring. A solid-state imaging device, comprising: a non-connecting portion that disconnects an electrical connection of the transfer electrodes extending in the horizontal direction of the two-dimensional array in the horizontal direction between the regions. 2. The solid-state imaging device according to claim 1, wherein the non-connection portion is provided for each shunt wiring corresponding to an integral multiple of the number of phases of a drive signal applied to the transfer electrode. element. 3. A plurality of light receiving regions arranged two-dimensionally in a matrix, a transfer electrode for transferring electric charges accumulated in each light receiving region in a vertical direction of the two-dimensional arrangement, and each light receiving region. A solid-state imaging device, comprising: a shunt wiring disposed so as to extend along a direction in which charges are transferred by the transfer electrode; and a contact portion that electrically connects the transfer electrode and the shunt wiring. The electrical connection in the horizontal direction of the transfer electrodes extending in the horizontal direction of the two-dimensional array between the light receiving regions,
A disconnection portion is provided for each shunt wiring corresponding to an integral multiple of the number of phases of the drive signal applied to the transfer electrode, and the shunt wirings arranged in the horizontal direction in the two-dimensional array are provided with the non-connection portions. A method for driving a solid-state imaging device, wherein whether to supply the drive signal is switched for each shunt wiring group, which is one unit, by disconnection of a connection portion.