JP2003234466A - Solid-state image pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize low power consumption by suppressing the increase of a driving frequency and a driving voltage even in a solid-state image pickup device in which a chip size is large or the number of pixels is large. <P>SOLUTION: A light receiving area where light receiving parts 101 and vertical charge transferring parts (VCCD) 102 adjacent to the light receiving parts 101 are arranged like a two-dimensional plane is divided into almost halves to the longitudinal direction of the VCCD 102, that is, vertically almost halves so that two system light receiving areas 111 and 112 can be obtained. The vertical edges of the light receiving areas 111 and 112 are respectively provided with horizontal charge transferring parts (HCCD) 121 and 122, the edge of each VCCD 102 is connected to those HCCD 121 and 122, and signal reading circuits 123 and 124 are respectively connected to the terminals of the HCCD 121 and 122. The two light receiving areas 111 and 112 are configured so that the moving directions (transferring directions) in the VCCD 102 of charges generated in the light receiving parts 101 can be made different from each other, and that they can be independently read out. <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, and more particularly, to a structure of a charge transfer section in an all-pixel readout type solid-state image pickup device.

[0002]

2. Description of the Related Art In recent years, electronic cameras (digital still cameras) for taking still images have become widespread. When capturing a still image, a solid-state image sensor of an all-pixel (progressive) read system is suitable as an image sensor, instead of an interlace read system of a so-called interlaced scan corresponding to a television signal. In shooting still images, unlike moving images, image quality such as resolution and color reproduction is an important factor, and the number of pixels (the number of pixels) of solid-state image pickup devices is rapidly increasing.

FIG. 9 shows a conventional interline transfer type CCD.
It is explanatory drawing which showed the schematic structure of (it is hereafter called IT-CCD). In the light receiving region 51, light receiving portions 52 formed by photoelectric conversion elements such as photodiodes are arranged in a square lattice shape,
A vertical charge transfer unit (V) that transfers the charges accumulated in the light receiving unit 52 in the vertical direction (vertical direction) is provided on the side of the row of the light receiving units 52.
CCD) 53 is extended. A horizontal charge transfer unit (HCC) for horizontally transferring charges is provided below the light receiving region 51.
D) 54 is provided, and the ends of each VCCD 53 are connected. An output amplifier (FD
A: A signal reading circuit 55 including a floating diffusion amplifier) is connected, and the signal charges are read out of the CCD element by the signal reading circuit 55.

Such an IT-CCD is widely used in consumer video cameras, and an interlaced readout type solid-state image pickup device is generally used. In order to read all pixels with a solid-state image sensor with a square lattice array,
As shown in the figure, VCCD is used for three-phase transfer pulses φ1, φ
It is necessary to drive with 2 and φ3. The HCCD is driven by two-phase transfer pulses H1 and H2.

Further, conventionally, since the image pickup device for the video camera has been improved and used for the digital still camera, the chip size (1/2 inch type, 2/3 inch type, etc.) is also adapted to the video camera. It was the mainstream.
However, there is a need to use a digital still camera under the same conditions as a conventional silver salt (film) camera, for example, using an interchangeable lens and a camera body in common, and for astronomical observation and medical applications, etc. Development of an image pickup device having an extremely large image pickup area is required. In the former case, for example, 135 size film or APS
An image pickup device having an image pickup area having a size corresponding to a film or a Brownie size film can be considered.

In the IT-CCD, the number of pixels is increased (the number of pixels is increased).
In that case, the number of transfer stages of the VCCD and the HCCD increases, so that it is necessary to increase the drive frequency and drive at high speed.
A so-called dual HCCD type solid-state image pickup device having two HCCD systems as shown in FIG. 10 has been proposed as a configuration of the solid-state image pickup device in which the transfer speed of the HCCD is increased. In this solid-state imaging device, two systems of HCCDs 61 and 62 are provided in parallel under a light receiving region 51, and each HCCD
Signal reading circuits 63 and 64 equipped with FDA or the like are connected to the ends of 61 and 62. These two systems of HCCD6
1, 62, the data transfer rate in the HCCD can be doubled.

Further, in a high-pixel (multi-pixel) solid-state image pickup device, it is important to suppress smear (such as vertical light bleeding appearing in an image when a high-luminance subject such as the sun is photographed). . A frame interline transfer CCD (hereinafter referred to as FIT-CCD) as shown in FIG. 11 has been developed as a high-quality CCD image pickup device having an ultra-low smear characteristic. In this solid-state image sensor, a storage region 57 for storing image signal charges for one field is provided below the light receiving region 51, and the HCCD 5 is provided below the storage region 57.
4 are provided.

Generally, the FIT-CCD has limited applications,
For example, it is used in applications such as broadcasting stations where particularly high image quality is required. In this case, an interlaced readout system is used for capturing a moving image based on the standard television system. The signal charges accumulated in the light receiving unit 52 are read out to the VCCD 52 during the vertical retrace line period,
At D52, a vertical transfer pulse is used to transfer the data at high speed to the storage area 57 for temporary storage (recording). Storage area 5
The signal charge stored in 7 is 1 using the horizontal blanking period.
Each horizontal line is sent to the HCCD 54, and the HCCD 54
It is transferred in the horizontal direction and guided to the output end of the signal reading circuit 55. In the FIT-CCD, since the VCCD can be operated at high speed to transfer the signal charge at high speed and send it to the storage area, the signal charge of each pixel stays in the VCCD for a short time and is not easily affected by smear. can do.

[0009]

In the solid-state image sensor as described above, the VCCD transfer electrode is an electrical contact (contact portion) with the drive signal supply path outside the light receiving area.
However, there is no such contact inside the light receiving area. Therefore, the number of pixels of the solid-state image sensor is increased (multi-pixel)
As the size of the chip increases, the electric resistance of the transfer electrode increases as it gets closer to the center of the light receiving region, and problems such as an increase in drive voltage and incomplete transfer become serious. Also, V
Since the number of transfer stages of CCD and HCCD increases as the number of pixels increases, it is necessary to increase the driving frequency, and there is a problem that an increase in power consumption cannot be avoided.

The above-mentioned conventional dual HCCD system I
In the T-CCD, when the driving frequency of the HCCD is the same, the substantial data transfer rate of the HCCD can be doubled, but the moving distance of the signal charges in the VCCD, that is, the time required for moving is not shortened. Therefore, an increase in driving voltage due to an increase in the electric resistance of the VCCD transfer electrode accompanying the increase in the number of pixels, an increase in the driving frequency for completing the charge transfer within a fixed time, and the like, and an increase in the power consumption due to the smear. The characteristics are not improved. Further, in the conventional FIT-CCD, the smear characteristic can be improved by moving the signal charges from the VCCD to the storage area at a high speed, but the number of transfer stages of the VCCD is increased, that is, the imaging area is further increased and the number of pixels is increased. In order to cope with this, an increase in drive voltage and an increase in drive frequency cannot be avoided, and there is a limit to high-speed drive from the viewpoint of charge transfer efficiency and power consumption.

As described above, in a solid-state image pickup device having a larger chip size or a larger number of pixels than the conventional general type, it is an object to suppress the increase of the drive frequency and the drive voltage and realize the low power consumption. Has become. In particular, in an all-pixel readout type solid-state imaging device mainly used for still image shooting, there is a strong need for larger size and higher pixel counts, so there is a demand for a configuration that can accommodate even larger size and higher pixel counts. .

The present invention has been made in view of the above circumstances, and an object thereof is to suppress an increase in drive frequency and drive voltage even in a solid-state image pickup device having a large chip size or a large number of pixels, and to reduce power consumption. An object of the present invention is to provide a solid-state imaging device capable of realizing the above.

Another object of the present invention is to shorten the time and distance for charges to move in the VCCD, thus increasing the size of the device.
It is an object of the present invention to provide a solid-state imaging device that can easily realize low power consumption without having to increase the driving frequency and the driving voltage even if the number of pixels is increased. Still another object of the present invention is to improve the data transfer rate of transfer charges without increasing the area of the HCCD, and to increase the drive frequency and drive voltage even if the device is enlarged and the number of pixels is increased. It is an object of the present invention to provide a solid-state image pickup device that can easily realize low power consumption.

[0014]

According to the present invention, a large number of light receiving portions are arranged on a semiconductor substrate at a constant pitch in a row direction and a column direction orthogonal to the row direction. A vertical charge transfer unit that extends in the column direction and transfers the charge generated in the light receiving unit in the light receiving unit column direction, and reads out the signal charge generated in the light receiving unit to the vertical charge transfer unit at once. A solid-state imaging device capable of reading out pixels,
The light receiving region in which the light receiving unit and the vertical charge transfer unit are arranged has a first light receiving region and a second light receiving region which are divided into two in the longitudinal direction of the vertical charge transfer unit. In the light receiving region, the charge transfer directions of the respective vertical charge transfer units are different from each other, and the horizontal charge transfer unit transfers the charges from the vertical charge transfer units to the ends of the first light receiving region and the second light receiving region. It is characterized in that each is provided with a charge transfer unit.

In the present invention, the light receiving region is divided into the first light receiving region and the second light receiving region, and vertical charge transfer is performed so that the charges generated in the light receiving portion in each light receiving region are transferred in the opposite directions. The maximum charge transfer distance is about 1 /
2 Therefore, the charge transfer time in the vertical charge transfer unit is shortened and the signal charge stays in the vertical charge transfer unit for a short time, so that the smear characteristic is improved. In this case, since the horizontal charge transfer section is provided in two systems corresponding to each light receiving area and is read from the output amplifier respectively, the data transfer rate is substantially doubled at the same drive frequency. Therefore, it is not necessary to increase the drive frequency even if the total number of pixels is large, and it is easy to increase the size of the image sensor (increasing the number of pixels) and reduce power consumption.

Further, according to the present invention, a large number of light receiving portions arranged on a semiconductor substrate in a row direction and a column direction orthogonal to the row direction and a plurality of light receiving portions extending in the column direction adjacent to the light receiving portions. And a vertical charge transfer unit that transfers the charges generated in the light receiving unit in the column direction of the light receiving unit, and all-pixel reading is possible in which the signal charges generated in the light receiving unit are read out to the vertical charge transfer unit at once. A solid-state imaging device, comprising a horizontal charge transfer unit for transferring charges from each vertical charge transfer unit at an end of a light receiving region in which the light receiving unit and the vertical charge transfer unit are arranged, and the horizontal charge transfer unit includes It has a first horizontal charge transfer section and a second horizontal charge transfer section divided into two in the longitudinal direction, and the charge transfer directions of these horizontal charge transfer sections are different from each other. Is characterized by.

According to the present invention, the horizontal charge transfer section is divided into the first horizontal charge transfer section and the second horizontal charge transfer section, and the charges are transferred in the opposite directions in the respective horizontal charge transfer sections to be output from the output amplifier. The maximum number of charge transfer stages in the horizontal charge transfer portion is about ½ so that the horizontal charge transfer portion can be read. Therefore, the data transfer rate of the signal charges output from the horizontal charge transfer section is substantially doubled at the same drive frequency. Therefore, it is not necessary to increase the drive frequency even if the total number of pixels is large, and it is easy to increase the size of the image sensor (increasing the number of pixels) and reduce power consumption.

Further, according to the present invention, a large number of light receiving portions arranged on a semiconductor substrate in a row direction and a column direction orthogonal to the row direction and a plurality of light receiving portions extending in the column direction adjacent to the light receiving portions. And a vertical charge transfer unit that transfers the charges generated in the light receiving unit in the column direction of the light receiving unit, and all-pixel reading is possible in which the signal charges generated in the light receiving unit are read out to the vertical charge transfer unit at once. In the solid-state imaging device, the light receiving region in which the light receiving unit and the vertical charge transfer unit are arranged is divided into two in the longitudinal direction of the vertical charge transfer unit, that is, a first light receiving region and a second light receiving region. In the light receiving regions, the charge transfer directions of the vertical charge transfer units are different from each other, and the vertical charge transfer units are provided at the end portions of the first light receiving region and the second light receiving region. Horizontal charge to transfer charge from Each of the horizontal charge transfer sections includes a first horizontal charge transfer section and a second horizontal charge transfer section, which are divided into two in the longitudinal direction. It is characterized in that the charge transfer directions are different from each other.

According to the present invention, the light receiving area is divided into the first light receiving area and the second light receiving area, and the vertical charge transfer is performed so that the charges generated in the light receiving section in each light receiving area are transferred in the opposite directions. The maximum charge transfer distance is about 1 /
2, and the horizontal charge transfer unit is divided into a first horizontal charge transfer unit and a second horizontal charge transfer unit, and charges are transferred in the opposite directions in each horizontal charge transfer unit and read out from the output amplifier. Thus, the maximum number of charge transfer stages in the horizontal charge transfer section is about 1/2. Therefore, the charge transfer time in the vertical charge transfer unit is shortened and the signal charge stays in the vertical charge transfer unit for a short time, so that the smear characteristic is improved. Further, since the horizontal charge transfer section has four systems, the data transfer rate is substantially increased by about four times at the same drive frequency. Therefore, it is not necessary to increase the drive frequency even if the total number of pixels is large, and it is easy to increase the size of the image sensor (increasing the number of pixels) and reduce power consumption.

Further, the present invention is characterized in that a charge storage region for temporarily storing charges from the vertical charge transfer unit is provided between the light receiving region and the horizontal charge transfer unit.

According to the present invention, a frame interline transfer type CCD (FIT-CCD) having a storage unit can be easily constructed. That is, in the FIT-CCD,
High-speed driving of the VCCD is required to reduce smear, but it is possible to increase the substantial data transfer rate at the same driving frequency, so that the FIT-CCD can be upsized and the number of pixels can be increased. Power consumption can be reduced compared to the conventional one. As a result, it is possible to realize an all-pixel-reading-type solid-state image sensor having ultra-low smear characteristics and low power consumption. It can be easily configured, the smear characteristics of this solid-state image pickup device can be improved, the data transfer rate can be increased, and the size of the image pickup device (pixel increase) and power consumption reduction can be achieved without increasing the drive frequency. It will be easier. For this reason,
It becomes possible to realize a solid-state image pickup device of an all-pixel readout system with ultra-low smear characteristics and low power consumption.

According to the present invention, the light receiving section of the light receiving region is
It is characterized in that the pixels of the light receiving portion adjacent to the pixels of a certain light receiving portion are arranged at positions shifted by about half of the pixel pitch in the row direction and the column direction.

In the present invention, the pixel of the light receiving portion is shifted by about 1/2 of the pixel pitch in the row direction and the column direction with respect to the adjacent pixel, so that the pixel array of the light receiving portion is arranged in a honeycomb shape. The configuration of any one of the above inventions is applied to the CCD image pickup device. In this case, in the all-pixel reading type solid-state image sensor, the transfer electrodes of the vertical charge transfer unit are
Since the layered polysilicon electrode can be used and the layout efficiency of the light-receiving portion and the vertical charge transfer portion in the light-receiving region is good, the solid-state imaging device can be easily increased in size (higher in number of pixels) and higher in density. Therefore, it is particularly effective to improve the smear characteristics and the data transfer rate by dividing the vertical charge transfer unit and the horizontal charge transfer unit described above, and to enlarge all (pixel increase) and low power consumption all-pixel reading A solid-state image sensor of the system can be realized.

[0024]

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 configuration explanatory view showing a configuration of a solid-state imaging device according to a first embodiment of the present invention, and FIG. 2 is an enlarged view of a light receiving part and a vertical charge transfer part of the solid-state imaging device. In the present embodiment, in the image pickup area (light receiving area) provided with the light receiving section by the photoelectric conversion element such as the photodiode, the light receiving section adjacent to a certain light receiving section is arranged at a position shifted by half the pixel pitch in the horizontal and vertical directions. That is, a configuration example in which a so-called honeycomb array CCD image sensor (hereinafter referred to as a honeycomb CCD) in which the pixel array of the light receiving portion is arranged in a honeycomb shape is used as a solid-state image sensor is shown. In addition,
The present invention can be similarly applied to a CCD image pickup device (hereinafter, referred to as a square lattice CCD) having a square lattice array in which light receiving portions are arranged in a square lattice.

As shown in FIGS. 1 and 2A, in the light receiving area of the solid-state image sensor, the light receiving section 101 and the vertical charge transfer section (VCCD) 102 adjacent to the light receiving section 101 are arranged in a two-dimensional plane. It is arranged. One horizontal pixel row in the light receiving unit 101 is offset from the adjacent pixel row in the horizontal direction (horizontal direction) by 1/2 of the horizontal pixel pitch, and one vertical pixel row is perpendicular to the adjacent pixel row. The so-called honeycomb arrangement is formed by arranging in the direction (vertical direction) with a shift of 1/2 of the vertical pixel pitch. That is, the light receiving units 101 are arranged in a state of being shifted by half the pixel pitch in the horizontal and vertical directions with respect to the adjacent light receiving units, and are located at the positions of the center points of the square lattices formed in the horizontal and vertical directions in a certain light receiving unit. The light receiving portions adjacent to each other are arranged. As a result, a light receiving region is formed in which the light receiving portions are arranged in a state in which a square lattice having a pitch of 1 / √2 of the pixel pitch in the horizontal and vertical directions is inclined by 45 degrees.

As shown in FIG. 2B, the light receiving section 101
Is composed of an embedded photodiode including a P-type low-concentration impurity region (P-well), an N-type high-concentration impurity layer 201, and a P-type high-concentration impurity layer 202 on the surface. The adjacent area around the light-receiving unit 101 has a vertical direction (see FIG.
A charge transfer path 203 made of an N-type high-concentration impurity for transferring the charge accumulated in the light receiving unit 101 is provided in a form meandering in the vertical direction in (A). Transfer electrodes 211 and 21 made of polysilicon having a two-layer structure of a first layer 204 and a second layer 205 are formed on the charge transfer path 203.
2, 213 and 214 are formed. The two-layer polysilicon electrode is formed by forming the first layer 204 and then forming the second layer 205 via the insulating film 208 so that the ends overlap.

A read gate 206 for reading out the charges accumulated by photoelectric conversion to the charge transfer path 203 is provided on one side of the outer periphery of the light receiving section 101, and the other side of the adjacent pixel column is vertically extended. An element isolation region (channel stop) 207 is formed by a P-type high-concentration impurity that blocks an electric charge from flowing in the charge transfer path. The insulating film 20 made of an oxide film such as SiO ₂ is formed on the surfaces of the light receiving portion 101, the charge transfer path 203, the first-layer polysilicon electrode 204, and the second-layer polysilicon electrode 205.
8 are formed and are electrically insulated from each other by the insulating film 208.

The VCCD 102 has the charge transfer path 203.
And the transfer electrodes 211 to 214, and the light receiving unit 10
1, the charge accumulated in 1 is transferred to the charge transfer path 203 in the vertical direction.
Is to be transferred along. This VCCD 102 has four transfer electrodes 211, 212, 2 for one pixel.
13, 214 are provided. Each transfer electrode extends in the horizontal direction and is formed in a meandering manner so as to avoid the light receiving portion 101. These transfer electrodes 211 and 211
12, 213, 214, for example, φ1, φ2, φ
Charge transfer path 20 is applied by applying four-phase transfer pulses of 3 and φ4.
3 can be driven to read all pixels.

The light receiving area having the light receiving portion 101 and the VCCD 102 is constituted by two light receiving areas 111 and 112 which are separated into two systems in the longitudinal direction of the VCCD 102, that is, approximately half, that is, approximately half in the vertical direction. In FIG. 1, the arrow line along the VCCD 102 indicates the transfer direction of the signal charge. Horizontal charge transfer units (HCCD) 121 and 122 for transferring charges in the horizontal direction are provided at the upper and lower ends of these light receiving regions 111 and 112, respectively.
The ends of D102 are connected. These HCCD1
The output amplifier (FD
A: signal reading circuits 123 and 124 each having a floating diffusion amplifier) are connected.

Although not shown, a protective film (planarizing film) is provided on the surface of the solid-state image sensor of this embodiment. A light-shielding film, a color filter, a microlens, and the like are formed on the surface protective film in the same manner as in a normal CCD image pickup device, and form a high-sensitivity color solid-state image pickup device.

In the two light receiving regions, in the first light receiving region 111 in the lower half and the second light receiving region 112 in the upper half, the moving direction (transfer direction) of the charges generated in the light receiving unit 101 in the VCCD 102 is the same. Differently, each is read independently. The charges generated in the light receiving portion of the first light receiving region 111 are transferred downward, and the first HCCD
Sent to 121. On the other hand, the second light receiving region 11
The electric charge generated in the second light receiving portion is transferred to the second H
It is sent to the CCD 122. The first light receiving region 111 and the second
The transfer path of the VCCD is not electrically connected to the light receiving area 112, and is not electrically connected, so that the charges in both areas are not mixed with each other. In the present embodiment, the two light receiving regions 111 and 112 are formed in the central portion of the semiconductor substrate in a meandering manner, and the element isolation region 12 is formed by a P-type high concentration impurity.
Separated by 5.

The VCCD 102 is driven by, for example, four-phase transfer pulses φ1 to φ4. In the present embodiment, transfer pulses having mutually different phases are supplied to the respective light receiving regions 111 and 112 at a predetermined timing, and the light receiving regions 111 and 112 are driven so that the signal charges are transferred in the opposite directions from the central portion in the vertical direction. The signal charges sent to the HCCDs 121 and 122 are the respective HCCDs 121 and 122.
The signal read circuit 12 at the end is transferred in the horizontal direction.
Signal charges are read out from the CCD 3,124 to the outside of the CCD element.

In the all-pixel readout type solid-state image sensor,
Since the interlaced reading is not performed, the correlation between the upper and lower horizontal lines is unnecessary, and the harmful effect of dividing the light receiving area into the upper and lower portions does not occur. Two divided light receiving areas 11
By reading out the signal charges from each of the pixels 1 and 112 and synthesizing them, an image signal for one screen obtained by photoelectrically converting the subject image on the light receiving region can be obtained.

In the honeycomb CCD, for example, in the case of the pixel configuration shown in FIG. 3, the pixel signals of each horizontal line are as follows: Line 1: GRGBGRGB ... Line 2: GBBGRGBGR. Since each line always contains R, G, and B color components, signal processing such as image signal thinning, addition, and complementation is easy, and an external line memory or the like is not required.

On the other hand, in the case of the square lattice CCD, for example, in the case of the pixel configuration shown in FIG.
Since it is composed only of color components of colors, an external line memory may be required for signal processing such as thinning, addition, and complement of image signals. Line 1 (ODD): GRGRGRGR ... Line 2 (EVEN): BGBGBGBG ...

As described above, in the present embodiment, each VCCD in the light receiving area of the solid-state image pickup device is vertically divided into approximately half and the upper half of the light receiving area is provided with the HCC.
In D, the lower half of the light receiving area is provided with HCC
The charge is transferred to and read from each D. As a result, the distance traveled by the charges in the VCCD, the number of transfer stages, and the time can be shortened. Therefore, the signal charge is V
The time spent in the CCD can be shortened and the smear characteristic can be improved. Further, since the HCCD has two upper and lower systems, the data transfer rate can be doubled at the same drive frequency as compared to the one having one HCCD.

Therefore, even if the chip size is increased or the number of pixels is increased, an increase in drive frequency and drive voltage is suppressed and power consumption can be reduced as compared with the conventional CCD.

FIG. 5 is a structural explanatory view showing a structure of a solid-state image pickup device according to a second embodiment of the present invention, and FIG. 6 is a structural explanatory view showing a schematic sectional structure of an HCCD in the second embodiment. The second embodiment shows an example in which the structure of the HCCD has a new structure.

The light receiving area having the light receiving portion 101 and the VCCD 102 is divided into two upper and lower light receiving areas 111 and 112, as in the first embodiment. These light receiving areas 1
HCCDs for transferring charges in the horizontal direction are provided at the upper and lower ends of 11, 112, respectively, and the ends of each VCCD 102 are connected. The HCCD of the second embodiment has two HCCDs 12 each of which is divided into approximately half in the longitudinal direction of the HCCD, that is, in the horizontal direction to have a length of about 1/2.
1A, 121B and HCCD 122A, 122B. These HCCD 121A, 121B, 1
Signal reading circuits 123A, 123B, and 124 having FDA or the like at the ends of 22A and 122B, respectively.
A and 124B are connected.

As shown in FIG. 6A, the HCCD 121
A and 121B (122A and 122B) are a P-type low concentration impurity region (P-well) 132 and an N-type low concentration impurity region (N-well (N well)) 133 on the N-type silicon substrate 131. Is formed, a P-type impurity region 134 is further formed thereon, and the gate oxide film 1 is further formed thereon.
This is a CCD register in which a two-layer polysilicon electrode composed of a first layer 137 and a second layer 138 is formed via 36. In addition, HCCD121A and HCCD121B and H
Between the CCD 122A and the HCCD 122B, there is an element isolation region 135 formed by a P-type high concentration impurity so that signal charges are not mixed with each other. HCCD12
1A, 121B, 122A and 122B are driven by two-phase transfer pulses H1 and H2. In this embodiment, as shown in FIG.
In the CCDs 121A (122A) and 121B (122B), transfer pulses H1 having opposite phases to each other at a predetermined timing.
H2 is supplied and driven so that the signal charges are transferred in the opposite directions from the central portion in the left-right direction.

The charges sent to the first HCCD 121A (122A) are transferred to the left and sent to the first signal reading circuit 123A (124A). On the other hand, the second HCC
The charges sent to D121B (122B) are transferred to the right and sent to the second signal reading circuit 123B (124B). Between the first HCCD 121A (122A) and the second HCCD 121B (122B), the transfer paths of the HCCD are electrically separated from each other and are not in conduction, so that the charges on both transfer paths are prevented from being mixed with each other. There is. HCCD1
21A, 121B, 122A and 122B respectively transfer the signal charges to the signal read circuits 123A and 123.
The data is read out from the B, 124A, and 124B to the outside of the CCD element.

In the solid-state image pickup device, as the size of the chip and the number of pixels increase, it becomes difficult to drive the HCCD at high speed. Therefore, in the second embodiment, the HCCD is divided into about half left and right to reduce the number of transfer stages to about ½, and the charges are moved in the opposite left and right directions to be read out independently, so that signals are generated even at the same drive frequency. The charge reading speed can be further increased. In this case, the data transfer rate of the HCCD can be increased to about 4 times as high as that of the HCCD having one system.

FIG. 7 is a structural explanatory view showing the structure of a solid-state image pickup device according to the third embodiment of the present invention. The third embodiment shows an example in which a storage region is provided in addition to the configuration of the first embodiment.

The light receiving area having the light receiving portion 101 and the VCCD 102 is divided into two upper and lower light receiving areas 111 and 112, as in the first embodiment. These light receiving areas 1
At both upper and lower ends of 11, 112, VCCD10
Storage areas 141, 14 for accumulating the charges transferred from
2 is provided, and an all-pixel read-out type FIT having a honeycomb structure
-It constitutes a CCD. The capacity of the storage area corresponds to the number of pixels of the light receiving area, and is a capacity (for one frame) capable of accumulating charges of substantially all the pixels. Since this storage region has no photodiode, the VCC in the storage region is
D is formed in a straight line without meandering. Two
Each of the storage areas 141 and 142 is driven by, for example, four-phase transfer pulses φs1 to φs4.

The HCCD 12 for transferring charges in the horizontal direction is provided at the upper and lower ends of the storage areas 141, 142, respectively.
1, 122 are provided to connect the transfer paths of the storage areas, and the signal readout circuits 123, 1 having FDA or the like are provided at the ends of the HCCDs 121, 122, respectively.
24 is connected.

The longer the charge stays in the VCCD in the light receiving area, the more the smear is affected. Therefore, in order to reduce the smear, it is important how quickly the charge in the VCCD is transferred to the shaded area. . The read speed of the HCCD is usually 10 to 20 MHz or higher, and it is difficult to dramatically increase the read speed. Therefore, in this embodiment,
A so-called FIT-CCD having a storage area is constructed, and the signal charge of each pixel is once transferred at a high speed to the storage area that is completely shielded, and then read out to the outside via the HCCD.

In this case, in order to quickly move the charges in the VCCD to the storage area, it is necessary to increase the frequency (driving frequency) of the transfer pulse supplied to the VCCD. In addition to this, the transfer distance of the VCCD is shortened. It is also effective to do. Therefore, in the third embodiment, as in the first embodiment, the VCCD in the light-receiving area is divided into two upper and lower parts, and
Two storage regions 141 and 142 are provided between the two independently driven HCCDs (upper and lower ends of the light receiving region).
Should be provided.

In the light receiving area, the charges generated in the light receiving portion of the first light receiving area 111 in the lower half are transferred downward, move to the first storage area 141 arranged below the light receiving area, and are temporarily stored. . On the other hand, the second light receiving area 1 in the upper half
The charges generated in the 12 light receiving portions are transferred upward, move to the second storage region 142 arranged above the light receiving region, and are temporarily stored. Then, from the storage areas 141, 142 to H
The signal charges sent to the CCDs 121 and 122 are horizontally transferred through the respective HCCDs 121 and 122, and the signal charges are CCs from the terminal signal reading circuits 123 and 124.
It is read out of the D element.

As described above, in this embodiment, the charge is VCC.
Since the distance to move in D can be shortened, the time required to move the charge to the storage region is about 1/2 of that in the conventional case at the same drive frequency, so the charge transfer time can be shortened and the smear effect It is possible to make it hard to receive.

Further, in this structure, since the storage regions having substantially the same area are provided above and below the light receiving region, the symmetry of the chip layout is enhanced, and the film thickness, shape, etc. of the microlenses and color filters can be kept more uniform. Has the effect of facilitating.

FIG. 8 is a structural explanatory view showing the structure of a solid-state image pickup device according to the fourth embodiment of the present invention. The fourth embodiment shows a configuration example in which the second embodiment and the third embodiment are combined.

The light receiving area having the light receiving portion 101 and the VCCD 102 is divided into two upper and lower light receiving areas 111 and 112, as in the first embodiment. These light receiving areas 1
At both upper and lower ends of 11, 112, VCCD10
Storage areas 141, 14 for accumulating the charges transferred from
2 is provided, and an all-pixel read-out type FIT having a honeycomb structure
-It constitutes a CCD. These storage areas 141, 1
At the upper and lower ends of 42, the left and right H
CCD 121A, 121B and HCCD 122A, 122
B is provided and each transfer path of the storage area is connected.
These HCCD 121A, 121B, 122A, 12
Signal reading circuits 123A, 123B, 124A, and 124B each having an FDA or the like are connected to the ends of 2B.

In the solid-state image pickup device, as the size of the chip and the number of pixels increase, it becomes difficult to drive the HCCD at high speed. Particularly in a CCD having a storage area, the driving frequency of the VCCD is high, and the power consumption of the entire device increases. Therefore, the fourth embodiment has a structure having the respective characteristics of the second embodiment and the third embodiment together to prevent an increase in power consumption. That is, the light receiving area is divided into two
The transfer path distance of the CD is about 1/2, and the HCCD is 2
In a charge reading structure that is divided into two and the number of transfer stages of the HCCD is about ½, it is configured to have two storage regions above and below the light receiving region.

As a result, the data transfer rate of the VCCD can be doubled and the data transfer rate of the HCCD can be doubled without increasing the driving frequency of the VCCD. Therefore, in the FIT-CCD requiring ultra-low smear characteristics, it is possible to easily increase the size of the element, increase the number of pixels, and reduce the power consumption, as compared with the conventional one. Further, in this configuration, since the storage regions having substantially the same area are provided above and below the light receiving region, the symmetry of the chip layout becomes high, and it becomes easy to keep the film thickness, shape, etc. of the microlenses and color filters more uniform. effective.

As described above, according to the structure of this embodiment, the VCCD in the light receiving region is divided into two, the charge transfer directions are made different from each other, and the charges are read out in the opposite direction.
Since the charge transfer time during D is shortened and the time during which the signal charge stays in the VCCD can be shortened, the smear characteristic can be improved. In this case, since the system has two HCCDs, the data transfer rate can be doubled. Furthermore, by dividing the HCCD into two, VCC can be maintained at the same drive frequency.
Since the time for the charge to move in D is shortened and four HCCDs are provided, the data transfer rate can be increased about four times. Therefore, even if the total number of pixels is doubled or quadrupled, it is not necessary to increase the driving frequency, and it is easy to increase the size of the CCD image pickup device (increasing the number of pixels) and reduce the power consumption. Therefore, the present embodiment is particularly effective for an element having a large chip size, an element having a large number of pixels, and an element that needs to be driven at high speed.

[0056]

As described above, according to the present invention, V
(EN) Provided is a solid-state image pickup device which can shorten the time and distance for electric charges to move in a CCD and does not need to increase the drive frequency and drive voltage even if the element is made larger and the number of pixels is increased, and can easily realize low power consumption. It is possible to Also, HCC
The data transfer rate of the transfer charge can be improved without increasing the area for arranging D, and it is not necessary to increase the drive frequency and drive voltage even if the element is made larger and the number of pixels is increased, and low power consumption is easily realized. It is possible to provide a solid-state imaging device that can do this.

Therefore, even in a solid-state image pickup device having a large chip size or a large number of pixels, it is possible to suppress an increase in driving frequency and driving voltage and to achieve low power consumption. In addition, since the charge transfer time in the vertical charge transfer unit is shortened and the signal charge stays in the vertical charge transfer unit for a short time, a solid-state imaging device having an ultra-low smear characteristic can be realized.

[Brief description of drawings]

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

FIG. 2 is an enlarged view showing a light receiving portion and a vertical charge transfer portion of the solid-state imaging device used in the embodiment of the present invention,
(A) is a plan view and (B) is a sectional view taken along line AA.

FIG. 3 is a configuration explanatory view showing an example of a pixel configuration of a honeycomb CCD and an output pixel signal.

FIG. 4 is a configuration explanatory diagram showing an example of a pixel configuration of a square lattice CCD and an output pixel signal.

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

FIG. 6 is a structural explanatory view showing a schematic sectional structure of an HCCD in the second embodiment.

FIG. 7 is a configuration explanatory diagram showing a configuration of a solid-state imaging device according to a third embodiment of the present invention.

FIG. 8 is a configuration explanatory diagram showing a configuration of a solid-state imaging device according to a fourth embodiment of the present invention.

FIG. 9 is a conventional interline transfer CCD (IT-C.
It is an explanatory view showing a schematic structure of (CD).

FIG. 10 is a conventional dual HCCD type IT-CCD.
It is an explanatory view showing a schematic configuration of.

FIG. 11 is a conventional frame interline transfer type CCD.
It is explanatory drawing which showed the schematic structure of (FIT-CCD).

[Explanation of symbols]

101 light receiving part 102 vertical charge transfer part (VCCD) 111, 112 light receiving regions 121, 122, 121A, 121B, 122A, 12
2B Horizontal charge transfer unit (HCCD) 123, 124, 123A, 123B, 124A, 12
4B Signal readout circuit 125, 133 Element isolation region 131 Silicon substrate 135 First layer (polysilicon electrode) 136 Second layer (polysilicon electrode) 141, 142 Storage region

Continued front page    F-term (reference) 4M118 AA04 AA10 AB01 BA12 BA13                       CA04 CA20 DA13 DB01 DB06                       DB07 DB08 FA02 FA06 FA26                       FA38 FA44 GC08                 5C024 CX00 CX13 CY42 EX43 EX52                       GX03 GX21 GY02 GY04 GY07                       GY18 GZ44 GZ47 JX25

Claims (5)

[Claims] 1. A plurality of light receiving sections arranged on a semiconductor substrate at a constant pitch in a row direction and a column direction orthogonal to the row direction, and a plurality of light receiving sections extending in the column direction adjacent to the light receiving sections. And a vertical charge transfer unit for transferring charges generated in the light receiving unit in the column direction of the light receiving unit, and capable of reading all pixels at one time to read out the signal charges generated in the light receiving unit to the vertical charge transfer unit. The light receiving region in which the light receiving unit and the vertical charge transfer unit are arranged has a first light receiving region and a second light receiving region which are divided into two in the longitudinal direction of the vertical charge transfer unit. In these light receiving regions, the charge transfer directions of the vertical charge transfer units are different from each other, and the charge from each vertical charge transfer unit is provided at the end of the first light receiving region and the second light receiving region. It is a horizontal charge transfer unit that transfers A solid-state imaging apparatus characterized by comprising been. 2. A plurality of light receiving sections arranged on a semiconductor substrate at a constant pitch in a row direction and a column direction orthogonal to the row direction, and a plurality of light receiving sections extending in the column direction adjacent to the light receiving sections. And a vertical charge transfer unit for transferring charges generated in the light receiving unit in the column direction of the light receiving unit, and capable of reading all pixels at one time to read out the signal charges generated in the light receiving unit to the vertical charge transfer unit. In addition, a horizontal charge transfer unit that transfers the charge from each vertical charge transfer unit is provided at the end of the light receiving region where the light receiving unit and the vertical charge transfer unit are arranged, and the horizontal charge transfer unit is arranged in the longitudinal direction. It is characterized by comprising a first horizontal charge transfer section and a second horizontal charge transfer section which are divided into two, and the charge transfer directions of these horizontal charge transfer sections are different from each other. Solid-state imaging device. 3. A plurality of light receiving sections arranged on a semiconductor substrate at a constant pitch in a row direction and a column direction orthogonal to the row direction, and a plurality of light receiving sections extending in the column direction adjacent to the light receiving sections. And a vertical charge transfer unit for transferring charges generated in the light receiving unit in the column direction of the light receiving unit, and capable of reading all pixels at one time to read out the signal charges generated in the light receiving unit to the vertical charge transfer unit. The light receiving region in which the light receiving unit and the vertical charge transfer unit are arranged has a first light receiving region and a second light receiving region which are divided into two in the longitudinal direction of the vertical charge transfer unit. In these light receiving regions, the charge transfer directions of the vertical charge transfer units are different from each other, and the charge from each vertical charge transfer unit is provided at the end of the first light receiving region and the second light receiving region. It is a horizontal charge transfer unit that transfers The horizontal charge transfer section comprises a first horizontal charge transfer section and a second horizontal charge transfer section which are divided into two in the longitudinal direction, and the horizontal charge transfer section has charge transfer directions. The solid-state imaging device is characterized by being configured so as to be different from each other. 4. The charge storage region according to claim 1, further comprising a charge storage region between the light receiving region and the horizontal charge transfer unit for temporarily storing charges from the vertical charge transfer unit. The solid-state imaging device described. 5. The light receiving section of the light receiving area is arranged such that a pixel of the light receiving section adjacent to a pixel of a certain light receiving section is shifted by about half of a pixel pitch in the row direction and the column direction. The solid-state imaging device according to any one of claims 1 to 4.