JP2005294398A - Image pickup element and image pickup element device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image pickup element which can transfer an electric signal to a reading part at high speed from a light receiving part, and to provide an image pickup element device using the element. <P>SOLUTION: A potential slope where potential on the electric signal sequentially changes from a photodiode 2 to a gate electrode 3 is arranged in the CCD-type solid-state image pickup element (CCD) 1. To put it concretely, impurity constituting the photodiode 2 is diffused in an "X" shape, and width L of impurity is constituted to sequentially extend from the photodiode 2 to the gate electrode 3. Thus, the electric signal is smoothly transferred along the potential slope P without stop of the electric signal from the photodiode 2 to the gate electrode 3 by arranging the slope. Consequently, the electric signal can be transferred at high speed from the photodiode 2 to the gate electrode 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image pickup device including a light receiving portion that receives incident light by converting incident light into an electric signal, a reading portion that reads out an electric signal obtained from the light receiving portion, and an image pickup device using the same. Relates to the device.

As this type of imaging device, for example, there is a CCD (Charge Coupled Device) type solid-state imaging device. Such a CCD solid-state imaging device (hereinafter abbreviated as “CCD”) is obtained from a photodiode corresponding to a light receiving portion that receives incident light by converting incident light into an electrical signal, and the photodiode. And a gate electrode corresponding to a reading unit for reading an electric signal. (For example, refer to Patent Document 1).
JP 2001-127277 A (page 5-7, FIG. 1, FIG. 2, FIG. 5, FIG. 6)

  However, when a CCD is used in a high-speed imaging device, there are the following problems.

  In the case of high-speed imaging, the exposure time is shortened. Therefore, the amount of exposure is reduced, and the amount of electric signal generated by the photodiode is also reduced accordingly. Therefore, it is conceivable to increase the exposure amount by making light incident on the photodiode with strong illumination or increasing the area of the photodiode. However, when the exposure area is increased by increasing the area of the photodiode, the distance from the photodiode to the gate electrode becomes longer, and the transfer time from the photodiode to the gate electrode becomes longer. As a result, the transfer time from the photodiode through the gate electrode also becomes long, and it becomes difficult to transfer at high speed. As described above, when high-speed imaging is performed, the exposure amount is reduced, and there is a problem that high-speed imaging cannot be performed if the area of the photodiode is increased in order to increase the exposure amount.

  The present invention has been made in view of such circumstances, and provides an imaging device capable of transferring an electrical signal from a light receiving unit to a reading unit at high speed, and an imaging device device using the imaging device. Objective.

  In order to achieve such an object, the present invention has the following configuration.

  That is, the invention according to claim 1 is an image pickup device including a light receiving unit that receives incident light by converting incident light into an electric signal, and a reading unit that reads out an electric signal obtained from the light receiving unit. In this case, a potential gradient is provided in which a potential relating to an electric signal sequentially changes from the light receiving portion toward the reading portion.

  [Operation / Effect] According to the invention described in claim 1, the light receiving unit receives the light by converting the incident light into an electric signal, and the reading unit receives the electric power obtained from the light receiving unit. Read the signal. At this time, by providing a potential gradient in which the potential related to the electric signal sequentially changes from the light receiving unit to the reading unit, the electric signal does not stagnate from the light receiving unit to the reading unit, and the electric signal is moved along the potential gradient. Is transferred smoothly. As a result, an electrical signal can be transferred from the light receiving unit to the reading unit at high speed.

  According to a fourth aspect of the present invention, there is provided an imaging device comprising: a light receiving unit that receives incident light by converting incident light into an electric signal; and a reading unit that reads out an electric signal obtained from the light receiving unit. An image sensor device using the above-described device is characterized in that a potential gradient in which a potential related to an electric signal sequentially changes from a light receiving portion toward the reading portion is provided.

  [Operation / Effect] According to the invention described in claim 4, by providing a potential gradient in which the potential relating to the electric signal sequentially changes from the light receiving unit to the reading unit, electric power is generated between the light receiving unit and the reading unit. The electric signal is smoothly transferred along the potential gradient without delaying the signal, and the electric signal can be transferred from the light receiving unit to the reading unit at a high speed.

  In the above-described inventions according to claims 1 and 4, examples of the potential gradient include the following. For example, the potential gradient may be provided by sequentially increasing the width of impurities constituting the light receiving unit from the light receiving unit toward the reading unit (inventions according to claims 2 and 5). In addition, a potential gradient may be provided by sequentially increasing the concentration of impurities constituting the light receiving unit from the light receiving unit toward the reading unit (inventions according to claims 3 and 6).

Further, in the invention according to any one of claims 4 to 6 (apparatus for image pickup device), the apparatus is an analysis device for performing analysis using data of electric signals obtained by the image pickup device, or only data. It may be used as a transfer device for transferring stored and stored data to an external device, or as an imaging device that captures an optical image of a subject, and a light receiving unit converts the captured optical image into an electrical signal to image the subject. It may be used. In the case of the imaging apparatus, the above-described crystal body that captures the optical image of the subject is provided (the invention according to claim 7). In addition, when the imaging device transfers an electrical signal at a high speed, such as a high-speed imaging device having a shooting speed of 1.0 × 10 ⁶ frames / second (1,000,000 frames / second), the present invention is used. Is particularly useful. In the present specification, “high-speed shooting” means that the shooting speed is 100,000 frames / second or more.

  According to the imaging device and the imaging device device using the imaging device according to the present invention, by providing a potential gradient in which the potential related to the electrical signal sequentially changes from the light receiving unit to the reading unit, the light receiving unit to the reading unit can be provided. The electric signal is smoothly transferred along the potential gradient without any delay in the electric signal, and the electric signal can be transferred from the light receiving unit to the reading unit at a high speed.

  Embodiment 1 of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration of a CCD solid-state imaging device (CCD) according to the first embodiment, and FIG. 2A is a plan view illustrating a configuration of each photodiode included in the CCD. 2B is a schematic diagram of the potential shape of the A-B cross section of FIG. 2A, and FIG. 3 is an explanatory diagram of a conventional CCD for comparison with FIG. 3 (a) is a plan view showing the structure of each photodiode constituting the CCD, and FIG. 3 (b) is a schematic diagram of the potential shape of the A-B cross section of FIG. 3 (a). FIG. 4 is a block diagram illustrating an outline of a high-speed imaging device using the CCD according to the first embodiment.

  As shown in FIG. 1, the CCD 1 includes a photodiode 2 that receives light by converting incident light into an electric signal, and a gate electrode 3 that reads an electric signal obtained from the photodiode 2. A plurality of storage CCD cells 4 (four in FIG. 1) for storing the electrical signals read by the gate electrode 3 are provided. The photodiode 2, the gate electrode 3, and the plurality of storage CCD cells 4 are arranged in a matrix form along the two-dimensional array line. The CCD 1 corresponds to the image sensor in the present invention, the photodiode 2 corresponds to the light receiving portion in the present invention, and the gate electrode 3 corresponds to the readout portion in the present invention.

  Of the storage CCD cells 4 arranged in a vertical and horizontal matrix, each storage CCD cell 4 on the most downstream side is connected to a vertical transfer gate 5, and each vertical transfer gate 5 is connected to a horizontal transfer gate 6. It is connected. Each time the electrical signal read out by the gate electrode 3 is sequentially stored in each storage CCD cell 4 and a charge transfer signal synchronized with the electronic shuttering operation is applied to the gate electrode 3 as a gate voltage, it is adjacent. The data are sequentially transferred to the accumulating CCD cell 4 in the direction (horizontal direction) indicated by the arrow in FIG. When all charges are stored as electrical signals in the storage CCD cells 4 arranged in the horizontal direction, they are transferred to the vertical transfer gate 5 in the vertical direction and transferred to the horizontal transfer gate 6 in the horizontal direction.

  The electric signal thus transferred is transferred to the outside of the CCD 1 (AD converter or image processing arithmetic unit of the high-speed imaging device), and various processes are performed to output an image.

  As shown in FIG. 2, a potential gradient P in which a potential related to an electric signal sequentially changes from the photodiode 2 toward the gate electrode 3 is provided. For comparison with FIG. 2, the conventional CCD shown in FIG. 3 will be used together. 2 and FIG. 3 includes an impurity diffusion region, and thus corresponds to an impurity region.

  As shown in FIG. 3A, the conventional CCD 51 has a rectangular photodiode 52. The line A-B in FIG. 3A includes the photodiode 52 to the gate electrode 53, and the potential shape of the cross section AB is as shown in FIG. That is, after the potential increases from the peripheral portion of the photodiode 52 to the vicinity of the center, the same level of potential is maintained from the vicinity of the center to the gate electrode 53. Therefore, the flow F of the electric signal in FIG. 3A is directed to the vicinity of the center, and the electric signal is stagnated in the vicinity of the center of the photodiode 52 (see the vicinity C of the center in FIG. 3A).

  On the other hand, as shown in FIG. 2A, the CCD 1 according to the first embodiment has an “X” -shaped photodiode 2. The width of the impurity constituting the photodiode 2 is “L” as shown in FIG. The “X” -shaped photodiode 2 is configured so that the width L of the impurity gradually increases from the photodiode 2 toward the gate electrode 3. Similarly to FIG. 3A, the line AB in FIG. 2A includes the photodiode 2 to the gate electrode 3, and the potential shape of the AB cross section is as shown in FIG. 2B. become. That is, as shown in FIG. 2B, even after the potential gradually increases from the peripheral portion of the photodiode 2 to the vicinity of the center, the potential sequentially changes from the vicinity of the center to the gate electrode. Therefore, the flow F of the electric signal in FIG. 2B is directed to the data electrode 3 even after going to the vicinity of the center, and the electric signal does not stagnate between the photodiode 2 and the gate electrode 3.

  In the process of manufacturing the CCD, the photodiode 2 may be configured by diffusing (doping) impurities in an “X” shape as shown in FIG. By configuring the photodiode 2 in this way, a potential gradient P is formed in which the potential related to the electrical signal sequentially changes from the photodiode 2 toward the gate electrode 3.

The CCD 1 shown in FIGS. 1 and 2 is used in the high-speed imaging device 10 shown in FIG. 4 in the first embodiment. In the first embodiment, the high-speed imaging device 10 having a shooting speed of 1.0 × 10 ⁶ frames / second (1,000,000 frames / second) is used. The high-speed imaging device 10 is configured such that an optical image of a subject is captured, and the captured optical image is converted into an electrical signal by the photodiode 2 to capture the subject. That is, the high-speed imaging apparatus includes an optical system 20, a CCD 1, an AD converter 30, an image processing calculation unit 40, an image storage unit 50, a monitor 60, an operation unit 70, and a control unit 80. The high-speed imaging device 10 corresponds to the imaging device device in this invention.

  The optical system 20 includes a lens 21 that captures an optical image of a subject, a photomultiplier mechanism (not shown) such as an image intensifier, a mechanical shuttering mechanism (not shown), and the like. The AD converter 30 converts the electrical signal output from the CCD 2 into a digital signal. The image processing calculation unit 40 performs various calculation processes to create a two-dimensional image of the subject based on the electrical signal digitized by the AD converter 30. The image storage unit 50 stores the two-dimensional image created by the image processing calculation unit 40. The monitor 60 outputs the two-dimensional image stored in the image storage unit 50 to the screen. The operation unit 70 performs various operations necessary for executing high-speed imaging. The control unit 80 performs overall control of the entire apparatus in accordance with operations such as shooting conditions set by the operation unit 70. The lens 21 corresponds to the crystalline lens in the present invention.

  According to the CCD 1 and the high-speed imaging device 10 using the CCD 1 described above, the photodiode 2 receives light by converting incident light into an electrical signal, and the gate electrode 3 is obtained from the photodiode 2. Read the electrical signal. At this time, by providing a potential gradient P in which the potential related to the electric signal sequentially changes from the photodiode 2 toward the gate electrode 3, the electric potential does not stagnate between the photodiode 2 and the gate electrode 3, and the potential gradient is increased. The electrical signal is smoothly transferred along P. As a result, an electrical signal can be transferred from the photodiode 2 to the gate electrode 3 at high speed.

  In the first embodiment, the potential gradient P is provided by sequentially increasing the width L of the impurities constituting the photodiode 10 from the photodiode 2 toward the gate electrode 3.

  In addition, the present invention is particularly useful when an electrical signal is transferred at high speed as in the high-speed imaging device 10 of the first embodiment.

  Next, Embodiment 2 of the present invention will be described with reference to the drawings.

  FIG. 5 is a plan view showing the configuration of each photodiode constituting the CCD according to the second embodiment.

In the second embodiment, the CCD 1 has a rectangular photodiode 2 having the same shape as the photodiode 52 (see FIG. 3) of the conventional CCD 51. The concentration of the impurities constituting the photodiode 2 is diffused (doped) so as to increase sequentially from the photodiode 2 toward the gate electrode 3. For example, when the photodiode 2 is divided into regions a ₁ , a ₂ , a ₃ , and a ₄ as shown in FIG. 5, impurities doped in the order of the regions a ₁ , a ₂ , a ₃ , and a ₄ Try to increase the concentration. By configuring the photodiode 2 in this way, a potential gradient P is formed in which the potential related to the electrical signal sequentially changes from the photodiode 2 toward the gate electrode 3.

  According to the second embodiment, the potential gradient P is provided by sequentially increasing the concentration of impurities constituting the photodiode 2 from the photodiode 2 toward the gate electrode 3.

  The present invention is not limited to the above-described embodiment, and can be modified as follows.

  (1) In the first and second embodiments described above, the high-speed imaging device has been described as an example. However, a normal imaging device having a shooting speed of less than 100,000 frames / second may be used.

  (2) In the first and second embodiments described above, an image pickup device represented by a high-speed image pickup device or the like has been described as an example of an image pickup device device using an image pickup device represented by a CCD or the like. If it is an apparatus used, it will not specifically limit. For example, it may be used as an analyzer that performs analysis using electrical signal data obtained by an imaging device, or a transfer device that stores only data and transfers the stored data to an external device.

  (3) In the first and second embodiments, the photodiode is described as an example of the light receiving unit, but the present invention is not limited to this. For example, a photogate may be used as the light receiving unit.

  When a photogate is used as the light receiving portion, a potential gradient may be provided depending on the shape of the gate electrode above the photogate. For example, as shown in FIG. 6, the gate electrode 3 ′ above the photogate 2 ′ is formed in a “Y” shape. Then, the potential gradient P may be provided by sequentially increasing the width L ′ of the gate electrode 3 ′ from the photogate 2 ′ toward the gate electrode 3 ′. Even in the case of a photogate, the concentration and shape of impurities constituting the photogate 2 'may be set as in the embodiment. Further, a potential gradient may be provided by impurities, and a potential gradient may be provided by the shape of the gate electrode 3 ′.

  (4) In Example 1 described above, as shown in FIG. 2, the photodiode 2 is formed in an “X” shape, and the width L of the impurity is gradually expanded from the photodiode 2 toward the gate electrode 3. The shape of the photodiode 2 is not limited.

  (5) You may combine Example 1 and Example 2 which were mentioned above. That is, the impurity width L may be increased gradually from the photodiode 2 toward the gate electrode 3, and the impurity concentration may be increased sequentially from the photodiode 2 toward the gate electrode 3.

1 is a block diagram illustrating a configuration of a CCD solid-state imaging device (CCD) according to Embodiment 1. FIG. (A) is a top view which shows the structure for every photodiode which comprises CCD, (b) is a schematic diagram of the potential shape of the AB cross section of (a). FIG. 3 is an explanatory diagram of a conventional CCD for comparison with FIG. 2, wherein (a) is a plan view showing a configuration of each photodiode constituting the CCD, and (b) is a plan view of (a). It is a schematic diagram of the potential shape of an A-B cross section. 1 is a block diagram illustrating an outline of a high-speed imaging device using a CCD according to Embodiment 1. FIG. 6 is a plan view showing a configuration of each photodiode constituting the CCD according to Embodiment 2. FIG. It is a top view which shows the structure for every photogate based on this invention.

Explanation of symbols

1 ... CCD
2 ... Photodiode 3 ... Gate electrode 10 ... High-speed imaging device 21 ... Lens P ... Potential gradient L ... Impurity width F ... Electric signal flow

Claims (7)

  An imaging device including a light receiving unit that receives incident light by converting incident light into an electric signal, and a reading unit that reads out an electric signal obtained from the light receiving unit, from the light receiving unit to the reading unit An image pickup device characterized by providing a potential gradient in which a potential related to an electric signal changes sequentially.   The imaging device according to claim 1, wherein the potential gradient is provided by sequentially expanding a width of an impurity constituting the light receiving unit from the light receiving unit toward the reading unit.   3. The image sensor according to claim 1, wherein the potential gradient is provided by sequentially increasing a concentration of an impurity constituting the light receiving portion from the light receiving portion toward the reading portion. Image sensor.   An image sensor device using an image sensor including a light receiving unit that receives light by converting incident light into an electric signal, and a reading unit that reads an electric signal obtained from the light receiving unit, An apparatus for an image sensor, comprising a potential gradient in which a potential related to an electric signal sequentially changes from a light receiving unit toward the reading unit.   5. The image sensor device according to claim 4, wherein the potential gradient is provided by sequentially widening the width of an impurity constituting the light receiving unit from the light receiving unit toward the reading unit. apparatus.   6. The image sensor device according to claim 4 or 5, wherein the potential gradient is provided by sequentially increasing the concentration of impurities constituting the light receiving unit from the light receiving unit toward the reading unit. An image sensor device. 7. The image sensor device according to claim 4, wherein the device captures an optical image of a subject, and the light receiving unit converts the captured optical image into an electric signal to capture an image of the subject. An image sensor device, comprising: a crystal body that is used as an image pickup device and captures an optical image of the subject.

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