JPH05326914A - Solid-state image sensing device - Google Patents

Abstract

PURPOSE:To increase the maximum amount of charge that can be transferred to the value larger than the conventional value without deteriorating the reading characteristic when the signal charge from a photoelectric conversion part is read out. CONSTITUTION:In a solid-state image sensing device, a special transfer electrode 3 and an electrode 4, which also serves the role of transfer reading, are arranged on a charge transfer part 2. The width of the electrode 4, which also serves the role of the transfer reading, is decreased toward the opposite side from the signal reading side at a constant ratio.

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 used for an image sensor, an image scanner or the like.

[0002]

2. Description of the Related Art In recent years, solid-state image pickup devices have rapidly spread in place of image pickup tubes for both industrial and home use. However, the number of electrodes required to drive the solid-state imaging device has increased, and the power consumption has accordingly increased. As one method of reducing this power consumption, a structure provided with a transfer / reading electrode that can be used for both reading and transferring the signal charges from the photoelectric conversion unit in order to reduce the number of electrodes has been proposed.

A conventional solid-state image pickup device will be described below with reference to the drawings. FIG. 5 is a schematic diagram of an imaging surface of a conventional solid-state imaging device. In FIG. 5, reference numeral 1 is a photoelectric conversion part made of an N-type semiconductor region, 2 is a charge transfer part made of an N-type semiconductor region, 3 is a lower first transfer-dedicated electrode, 4 is an upper first-read / read electrode. Is a second transfer-dedicated electrode in the lower layer, and 6 is a second transfer / readout electrode in the upper layer.

The operation of the solid-state image pickup device configured as described above will be described below. First, when light enters the photoelectric conversion unit 1, signal charges are generated and accumulated. Then, within the vertical blanking period, the electrode 4 or 6 also serving as the readout and reading
When a read pulse is applied to, the accumulated signal charges are read to the charge transfer unit 2. The signal charges read out thereafter are transferred to the charge transfer unit 2 when a transfer pulse is applied to the transfer dedicated electrodes 3 and 5 and the transfer read / read electrodes 4 and 6.
Transferred in. In this case, when a high voltage is applied to the transfer / reading combined electrode 4, signal charges are read out from the photoelectric conversion unit 1 to the charge transfer unit 2, so that the transfer-dedicated electrode 5 is transferred at the time of transfer.
There is a restriction that a high voltage cannot be applied,
Considering that point, one electrode can be used as the charge transfer electrode and the charge read electrode. In this way
It is possible to reduce the number of electrodes and prevent an increase in power consumption.

[0005]

However, in the above-mentioned conventional configuration, the area occupied by the transfer-dedicated electrodes is only about 50% of all transfer electrodes. Therefore, when the voltage of the pulse applied to the transfer-dedicated electrodes is increased. However, there is a problem that the maximum transferable charge amount cannot be increased so much.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a solid-state image pickup device capable of further increasing the maximum transferable charge amount.

[0007]

In order to achieve this object, a solid-state image pickup device according to the present invention has a transfer-dedicated electrode and a transfer-read / read electrode arranged on an electric charge transfer section via an insulating film. The width of the transfer / read electrode also decreases from the side from which the signal charge is read to the side opposite thereto at a constant rate.

[0008]

With this configuration, the width of the signal reading side of the transfer / read-out electrode, that is, the photoelectric conversion portion side is equal to that in the conventional case, and the area occupied by the transfer-dedicated electrode can be made larger than in the conventional case. When the pulse voltage is increased, the maximum transferable charge amount can be increased more than before.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A solid-state image pickup device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of an image pickup surface of a solid-state image pickup device according to the first embodiment of the present invention. In FIG. 1, reference numeral 1 is a photoelectric conversion unit made of an N-type semiconductor region, 2 is a charge transfer unit made of an N-type semiconductor region, 3
Is a lower-layer first transfer / read-only electrode, 4 is an upper-layer first transfer / read-only electrode, 5 is a lower-layer second transfer-only electrode, and 6 is an upper-layer second transfer-read / read electrode. In this embodiment, the width of the first transfer / read-only electrode 4 is narrowed from the photoelectric conversion portion 1 side to the opposite side at a constant rate, and the area of the first transfer / dedicated electrode 3 is increased accordingly. Therefore, although the read characteristic from the photoelectric conversion unit 1 is equivalent to that of the conventional one, the area of the first transfer-dedicated electrode 3 increases, and as a result, the maximum transfer charge amount increases.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a schematic view of the image pickup surface of the solid-state image pickup device according to the second embodiment of the present invention. In the present embodiment, the width of the first transfer / readout combined electrode 4 is set to the photoelectric conversion unit 1.
It is constant from the side to a predetermined position and then narrows at a constant rate. In this case as well, the read characteristic from the photoelectric conversion unit 1 is equivalent to that of the conventional one, but the area of the first transfer-dedicated electrode 3 increases, and as a result, the maximum transfer charge amount increases.

Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a schematic diagram of an image pickup surface of a solid-state image pickup device according to the third embodiment of the present invention. In the present embodiment, the width of the first transfer / readout combined electrode 4 is set to the photoelectric conversion unit 1.
The width is constant from the side to a predetermined position, and thereafter, the width is once narrowed and has a constant width. In this case as well, the read characteristic from the photoelectric conversion unit 1 is equivalent to that of the conventional one, but the area of the first transfer-dedicated electrode 3 increases, and as a result, the maximum transfer charge amount increases.

Next, the maximum transferable charge amount in the above-mentioned first, second and third embodiments will be described. Figure 4 (a)
FIG. 4 is a diagram schematically showing the maximum transferable charge amount of the solid-state imaging device in the example of the present invention, and FIG.
The maximum transferable charge amount of the conventional solid-state imaging device is shown in (b). In these figures, the shaded area corresponds to the maximum transferable charge amount. As shown in FIGS.
In each of the embodiments of the present invention, the electrodes 4 and 6 also serving as the read / read function are all used.
The width of the portion for reading out the signal charges is the same as that of the conventional case shown in FIG. 5, and the reading characteristics are not changed. on the other hand,
By making the area occupied by the transfer-dedicated electrodes 3, 5 larger than in the conventional case, the transferable signal charge amount as shown in FIG. 4A can be made larger than that in the conventional case shown in FIG. 4B. it can.

Although the above description has been made only with respect to the first transfer-dedicated electrode 3 and the first transfer / read-only electrode 4, the same applies to the other transfer-dedicated electrodes and the transfer / read-only electrodes.

[0014]

As described above, according to the present invention, the transfer-dedicated electrode and the transfer / read / read electrode are arranged on the charge transfer portion via the insulating film, and the width of the transfer / read / read electrode reads the signal charge. It has a configuration in which it decreases from one side to the other side at a fixed rate, and the maximum transferable charge amount can be increased by increasing the area occupied by the transfer-dedicated electrode without degrading the signal reading characteristics. It is possible to realize an excellent solid-state imaging device that can be increased in number as compared with the related art.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an image pickup surface of a solid-state image pickup device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of an image pickup surface of a solid-state image pickup device according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram of an image pickup surface of a solid-state image pickup device according to a third embodiment of the present invention.

FIG. 4A is a diagram schematically showing the maximum transferable charge amount of the solid-state imaging device according to the embodiment of the present invention. FIG. 4B is a diagram schematically showing the maximum transferable charge amount of the conventional solid-state imaging device.

FIG. 5 is a schematic diagram of an imaging surface of a conventional solid-state imaging device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photoelectric conversion part 2 Charge transfer part 3 1st transfer-dedicated electrode (transfer-dedicated electrode) 4 1st transfer-reading combined electrode (transfer-reading combined electrode)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noboru Kokusenya 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electronics Industrial Co., Ltd. (72) Yukio Saito 1006 Kadoma, Kadoma City, Osaka Matsushita Electronics Industrial Co., Ltd. (72) Inventor Ryoichi Nagayoshi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electronics Industrial Co., Ltd.

Claims (3)

[Claims] 1. A photoelectric conversion part formed in a region of opposite conductivity type on the surface of a semiconductor substrate of one conductivity type, and charges for transferring signal charges generated in the photoelectric conversion part formed in a region of opposite conductivity type. A transfer section, a transfer-dedicated electrode for signal charge transfer on the charge transfer section, and a transfer / read-out electrode for both signal charge transfer and signal charge read; and the transfer-dedicated electrode on the charge transfer section. The transfer / read / use electrode is disposed via an insulating film, and the width of the transfer / read / use electrode is reduced at a constant rate from the side from which the signal charge is read to the opposite side. Solid-state imaging device. 2. A photoelectric conversion part formed in a region of opposite conductivity type on a surface of a semiconductor substrate of one conductivity type, and charges for transferring signal charges generated in the photoelectric conversion part formed in a region of opposite conductivity type. A transfer section, a transfer-dedicated electrode for signal charge transfer on the charge transfer section, and a transfer / read-out electrode for both signal charge transfer and signal charge read; and the transfer-dedicated electrode on the charge transfer section. The transfer / read-out electrode is disposed via an insulating film, and the width of the transfer / read-out electrode is constant from a side for reading out signal charges to a predetermined position from the side where the signal charges are read out to a predetermined position. A solid-state imaging device characterized by decreasing in proportion. 3. A photoelectric conversion part formed in a region of opposite conductivity type on the surface of a semiconductor substrate of one conductivity type, and a charge formed in the region of opposite conductivity type for transferring signal charges generated in the photoelectric conversion part. A transfer section, a transfer-dedicated electrode for signal charge transfer on the charge transfer section, and a transfer / read-out electrode for both signal charge transfer and signal charge read; and the transfer-dedicated electrode on the charge transfer section. The transfer / read-out electrode is disposed via an insulating film, and the width of the transfer / read-out electrode is constant from a side for reading out signal charges to a predetermined position from the side opposite to the side where the signal charges are read out, and thereafter the above-mentioned A solid-state imaging device having a constant width different from the width.