JPH04365274A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To obtain the solid-state image pickup device which can sufficiently reduce smear without increasing a chip area and has no unnatural distortion on a reproduced picture even when a camera is moved. CONSTITUTION:For this sold-state image pickup device, on a semiconductor substrate, photosensitive parts 11-18 arranged in the shape of a matrix are provided, a signal charge read part is provided to read signal charges stored in these photosensitive parts 11-18, signal charge transfer parts 21-28 are provided to unidirectionally transfer the signal charges read by the signal charge read part, and output parts 9 and 100 are provided to detect the signal charges transferred by the signal charge transfer parts 21-28 as output signals. The signal charge transfer parts 21-28 are respectively arranged in a row direction corresponding to the respective rows of the matrix-arranged photo-sensitive parts 11-18, and the signal charge transfer parts 21-28 are independently driven for each row.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging device, and more particularly to a solid-state imaging device that reduces smear suspicious signals.

0002

2. Description of the Related Art In recent years, solid-state imaging devices, which have the features of being smaller, lighter, and have a longer lifespan than image pickup tubes, have been widely used as an alternative to image pickup tubes. In particular, interline transfer CCD (hereinafter referred to as IT-CCD)
) are widely used in home video cameras, handheld cameras for broadcasting, etc.

However, solid-state imaging devices have a unique phenomenon called smear. Smear is a phenomenon in which the image of a high-brightness object draws thin bands above and below in an image, and this phenomenon has been a major problem, especially in broadcast video cameras. Recently, new problems have arisen, such as smear enhancement when the electronic shutter of a home video camera is operated, and input errors in industrial image data due to smear.

[0004] The cause of smear generation in IT-CCD is as follows.
Two points can be considered: lateral diffusion of charges generated within the Si substrate and leakage of light through the interlayer SiO2 film between the Si substrate and the Al light shielding film. In addition, as these measures,
Proposals include providing a double well around the CCD channel region and reducing the thickness of the interlayer SiO2 film to 0.2 μm. However, a sufficient reduction effect has not yet been obtained.

Furthermore, since smear occurs due to charge leaking into the transfer section during transfer, it can also be reduced by shortening the transfer time. Focusing on this, we created a frame transfer interline CCD that combines an IT-CCD and a frame transfer CCD.
(hereinafter referred to as FIT-CCD) has been proposed. However, in the FIT-CCD, since the signal charge accumulation region must be provided separately from the photosensitive region, there is a problem that the chip area increases.

Furthermore, whereas displays such as cathode ray tubes and liquid crystal panels scan one line at a time, CC
The D image sensor uses a method to read out the signals of all pixels to the transfer unit at the same time, and due to the difference in scanning method and readout method, there is a problem that distortion occurs on the playback screen of the display when a moving image is captured with a CCD. There is also.

[0007]

[Problems to be Solved by the Invention] As described above, the occurrence of smear is a major problem in conventional solid-state imaging devices, and conventional smear reduction measures may not have sufficient reduction effects or may lead to an increase in chip area. There was a problem. Furthermore, since there is a difference between the scanning method of the display and the signal reading method of the imaging device, there is a problem in that when a moving image is captured, distortion occurs on the playback screen.

The present invention has been made in consideration of the above circumstances, and its purpose is to be able to sufficiently reduce smear without increasing the chip area, and to be able to reduce smear even when the camera is moved. An object of the present invention is to provide a solid-state imaging device without unnatural distortion on a playback screen.

[0009]

[Means for Solving the Problems] The gist of the present invention is to select each row in chronological order without performing vertical transfer when transferring signal charges accumulated in photosensitive parts arranged in a matrix. The purpose is to perform horizontal transfer only.

That is, the present invention has a photosensitive section arranged in a matrix on a semiconductor substrate, a signal charge readout section for reading out signal charges accumulated in the photosensitive section, and a signal charge readout section that reads signal charges accumulated in the photosensitive section. A solid-state imaging device comprising a signal charge transfer section that transfers signal charges in one direction, and an output section that detects the signal charges transferred by the signal charge transfer section as an output signal, the signal charge transfer section comprising: It is characterized in that it is arranged in the row direction corresponding to each row of photosensitive parts arranged in a matrix, and the signal charge transfer parts are driven independently for each row.

[0011]

[Operation] According to the present invention, by driving the signal charge transfer sections arranged corresponding to each row of the photosensitive section independently for each row, the signal charges read out by the signal charge readout section are transferred vertically. The output signal can be extracted by transferring only in the horizontal direction without transferring in the horizontal direction. In this case, the signal charges accumulated in the photosensitive area are transferred only in the horizontal direction, which can be driven at high speed, so in principle, smearing is performed at the ratio of the horizontal transfer time to the conventional vertical transfer time. It becomes possible to reduce the amount. Also, F
Unlike IT-CCDs, there is no need to provide a separate storage region for signal charges, so there is no increase in chip area.

[0012] Furthermore, as a method for reading signal charges, it is possible to adopt a method adapted to the display scanning method in which signal charges in each row are sequentially read out in time series, so that even if a moving image is captured, it will not appear unnatural on the playback screen. No distortion occurs.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be explained below with reference to illustrated embodiments.

FIG. 1 is a schematic plan view showing the basic configuration of a solid-state imaging device according to an embodiment of the present invention. In FIG. 1, a photosensitive section 10 (11 to 1
8) are arranged in a matrix. In FIG. 1, in order to simplify the explanation, the number of lines is eight, and the same reference numerals are given to the photosensitive parts in the same line.

A horizontal transfer section 20 (21-28) consisting of a CCD is provided corresponding to the photosensitive sections 11-18. That is, the horizontal transfer sections 21 to 28 are arranged between the photosensitive sections 10 along the horizontal direction (row direction), and input signal charges from the adjacent photosensitive sections 11 to 18 and transfer them in the horizontal direction. It becomes.

As means for selectively applying drive pulses to these horizontal transfer units 21 to 28, a drive pulse input unit P is used.
1, P2, a drive pulse scanning section 3, and a mode switching section 4 for interlace operation. and,
The horizontal transfer units 21 to 28 are selectively driven.

The horizontal transfer units 21 to 28 are designed to transfer data by two-phase drive, and each transfer electrode has two
The book drive wirings 81 and 82 are connected. Further, the output unit 100 is configured so that the signals transferred in time series by the horizontal transfer units 21 to 28 can be outputted by one output unit 100.
A signal gathering section 9 consisting of a changeover switch and the like is provided between the horizontal transfer section 00 and the horizontal transfer sections 21 to 28.

FIG. 2 is a plan view of one pixel portion showing a more specific version of FIG. A signal charge readout section 5 is provided adjacent to the photosensitive section 10. Since the transfer section 20 operates with two-phase drive, barrier electrodes 61 and 71, which determine the transfer direction during the transfer of signal charges formed of the first layer poly-Si, and the second
Storage electrodes 62 and 72 formed of a poly-Si layer are provided to store signal charges during transfer of the signal charges. Further, electrodes 61 and 62, 71 and 72 are electrically connected by drive wiring lines 81 and 82, respectively, and a horizontal CCD channel 90 is formed below these electrodes. Furthermore, a portion of the electrodes 71 and 72 connected to the drive wiring 81 also serves as the gate of the signal readout section 5. Next, a method of driving the device of this embodiment will be explained.

FIG. 3 shows the input pulse waveform and the output waveform of the drive pulse scanning section 3 in this embodiment. Here, explanation will be given using frame accumulation operation. φP1 and φP2 shown in FIG. 3 are input to the drive pulse input sections P1 and P2, respectively.

[0020] φP1 is the value of the photosensitive portion 10 within one horizontal scanning period.
A pulse A for reading out signal charges accumulated in the signal charge readout unit 5, and a pulse B for horizontal direction transfer.
1, and half the number of A, B of all rows in one field period
It has a set of 1.

On the other hand, φP2 has a pulse B2 for horizontal transfer within one horizontal scanning period, and similarly to φP1, it has half the number of B2s of all rows in one field period. Here, since B1 and B2 are pulses for performing two-phase driving, they have opposite phases.

The drive pulse scanning section 3 has input sections P1 and P2.
Input pulses φP1, φP2 from the outside and a pulse φHD having a length of one horizontal period at the beginning of one field period from the outside.
is input. The drive pulse scanning unit 3 outputs φD11 to φD41 from these inputs to output terminals D11 to D41, respectively.
φD12 to φD42 are output to output terminals D12 to D42, respectively.

As shown in FIG. 3, φD11 to φD41 have one set of A and B1 during one field period, and φD1
They are arranged in the order of φD41 at timings shifted by one horizontal period. On the other hand, φD12 to φD42 are also B
2 are pulses arranged at timings shifted by one horizontal period. As a result, the horizontal transfer units are selectively driven in ascending order of number. Furthermore, a pulse that is inverted for each field is applied to the mode switching section 4, so that the output of the drive pulse scanning section 3 can be selectively applied to odd-numbered rows and even-numbered rows for each field for interlaced operation.

As described above, odd-numbered photosensitive sections 11, 13, 1 among the photosensitive sections 11 to 18 are arranged in odd-numbered fields.
Signals 5 and 17 are transferred and output in chronological order in ascending order. On the other hand, in an even field, the even numbered photosensitive areas 12
, 14, 16, and 18 are transferred and output in chronological order in ascending order. Since the signals of each row are selectively read out in time series in this way, it is compatible with the display scanning method.

Now, considering the transfer time related to the mixing of smear signals, one vertical transfer period (for one pixel) in a conventional solid-state imaging device corresponds to one horizontal transfer period. In contrast, in this embodiment, the signal charge is transferred only in the high-speed horizontal direction, and the total number of pixels in the horizontal direction is transferred in one horizontal transfer period, so the time for one transfer is shorter than the conventional transfer time. It becomes 1/the number of pixels in the horizontal direction. In principle, smear can be reduced by the proportion of this transfer time.

Next, the signal gathering section 9 in FIG. 1 will be explained. FIG. 4 shows a specific example of the signal gathering section 9. In FIG. 4, each horizontal transfer section 20 is provided with signal charge detection sections 111 to 118 independently. The output terminals of the signal charge detection units 111 to 118 are provided with an output mode switching unit 13 having the same function as the mode switching unit 4 described above.
is provided, and its output terminal is half the total number of rows in the horizontal transfer section. Output terminal 1 of output mode switching section 13
One of the MOS switches 121 to 124 is connected to each of the MOS switches 31 to 134, and the other ones are all connected to the output section 100. Further, the output terminal of the shift register 14 is connected to the gates of the MOS switches 121 to 124, and the MOS
O for each horizontal period in ascending order of switches 121 to 124
A pulse is applied so that the voltage becomes N. That is, the horizontal transfer section of the row transferring the signal sequentially outputs the output section 1 every horizontal period.
This means that it is connected to 00.

As described above, in this embodiment, the horizontal transfer section 20 is separated for each row of the photosensitive sections 10 arranged in a matrix.
Since signal charges are transferred only by high-speed horizontal transfer, smear can be significantly reduced. Furthermore, since there is no need to separately provide a signal charge accumulation region unlike in FIT-CCD, the chip area does not increase. In addition, since the signals of each row are read out sequentially in chronological order, the signal can be read out in a way that is compatible with the operating method of the display, making it possible to prevent unnatural distortion from occurring on the playback screen. .

Note that the present invention is not limited to the embodiments described above. In the embodiment, an example was shown in which MOS switches were used to output signals from multiple rows of horizontal CCDs from one output section, but between the horizontal transfer section and the output section, one Alternatively, two CCD transfer channels may be formed, and the CCD transfer channels may be bundled together and connected to the output section. In addition, although the example shows an example in which the photosensitive part and the signal charge transfer part are formed on the same surface, a multilayer type in which a photoconductive film as a photosensitive part is laminated on a solid-state image sensor chip as shown in FIG. It is also possible to apply this method to other solid-state imaging devices. In addition, various modifications can be made without departing from the gist of the present invention.

[0029]

[Effects of the Invention] As explained above, according to the present invention, when transferring signal charges accumulated in photosensitive parts arranged in a matrix, each row is selected in chronological order without performing vertical transfer. By performing only horizontal transfer, it is possible to sufficiently reduce smear without increasing the chip area, and to create a solid-state imaging device that does not cause unnatural distortion on the playback screen even when the camera is moved. It becomes possible to realize this.

[Brief explanation of drawings]

FIG. 1 is a plan view schematically showing the basic configuration of a solid-state imaging device according to an embodiment of the present invention;

FIG. 2 is a plan view of one pixel portion showing a more specific version of FIG. 1;

FIG. 3 is a signal waveform diagram for explaining the operation of the embodiment;

[
FIG. 4 is a circuit configuration diagram showing a specific configuration of the collection section used in the example.

[Explanation of symbols]

10 (11-18)...photosensitive part, 20 (21 to 28)...horizontal transfer section, 3, 13... drive pulse scanning section, 4...mode switching section, 9...Signal aggregation section, 14...Shift register, 61, 71...barrier electrode, 62, 72...storage electrode, 81, 82...drive wiring, 100...Output section.

Claims (2)

[Claims] 1. A photosensitive section arranged in a matrix on a semiconductor substrate, a signal charge readout section for reading out signal charges accumulated in the photosensitive section, and a signal charge readout section for reading out signal charges read out by the signal charge readout section. The signal charge transfer section includes a signal charge transfer section that transfers in one direction, and an output section that detects the signal charge transferred by the signal charge transfer section as an output signal, and the signal charge transfer sections are arranged in the matrix. A solid-state imaging device characterized in that the signal charge transfer sections are arranged in the row direction corresponding to each row of photosensitive sections, and the signal charge transfer section is driven independently for each row. 2. The output section detects a plurality of rows of signal charges transferred in time series from a plurality of signal charge transfer sections,
The solid-state imaging device according to claim 1, wherein the solid-state imaging device outputs to one output line.