JPH05110057A - Solid-state imaging device - Google Patents

Abstract

PURPOSE:To provide a solid-state imaging device improved in afterimage properties by a method wherein transfer sections where signal charge is inputted first after it is made to pass through a read gate are structured so as to enable a boundary line between the transfer sections not to cross the transfer direction of the signal charge at a right angle. CONSTITUTION:A solid-state image sensing device is composed of a photoelectric conversion element 1 where photoelectrically converted signal charge is stored; transfer sections 7 and 8 equipped with transfer gates which transfer signal charge, and a read gate 6 which reads out the signal charge from the photoelectric conversion element 1 to the transfer section 7; where a boundary line 11a of the transfer section T which signal charge is made to enter first after it passes through the read gate 6 is structured so as not to cross the transfer direction of signal charge at a right angle.

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.

[0002]

2. Description of the Related Art In recent years, the development of solid-state image pickup devices has progressed, and there are some that are comparable to or superior to image pickup tubes in terms of performance. Among them, the interline transfer type CCD solid-state imaging device (hereinafter abbreviated as IT-CCD) has particularly excellent characteristics and has been put to practical use.

A conventional solid-state image pickup device will be described below. FIG. 2 is a block diagram of a conventional IT-CCD. In FIG. 2, 1 is a photoelectric conversion element, 2 is a vertical CCD (hereinafter abbreviated as VCCD) that vertically transfers the signal charges accumulated in the photoelectric conversion element 1, and 3 is a horizontal CCD that transfers the signal charges transferred by the VCCD 2. Horizontal CCD to transfer (hereinafter HCCD
(Abbreviated)) 4 is an output amplifier unit for detecting the signal charges transferred by the HCCD 3.

FIG. 3 is a plan view of a main part of a conventional solid-state image pickup device, which is an enlarged view of a portion A surrounded by a broken line in FIG.
In FIG. 3, 5 is a separation region for separating the photoelectric conversion element 1, 6 is a read gate for reading out the signal charge from the photoelectric conversion element 1 to the VCCD 2, and 7 is the photoelectric conversion element 1 for the signal charge.
, A transfer unit for reading signal charges that first enters from the read gate 6, a transfer unit that only transfers signal charges, a gate width of the read gate 6, a unit pixel pitch, and a transfer unit A boundary line between 7 and the transfer unit 8 and 12 is a transfer direction of signal charges.

The operation of the conventional solid-state image pickup device configured as described above will be described below. First, the signal charges generated and accumulated in the photoelectric conversion element 1 enter the transfer unit 7 for reading the signal charges through the read gate 6.
Transfer electrodes (not shown) are provided on the transfer units 7 and 8, and a transfer pulse is applied to the transfer electrodes to transfer the signal charges of the transfer unit 7 to the transfer unit 8 to transfer the charge in the HCCD 3 shown in FIG. The signal charge is transferred to the output amplifier section 4.

In the conventional solid-state image pickup device, as shown in FIG. 3, the boundary line 11 between the transfer units 7 and 8 is determined by the boundary between the transfer electrodes and is orthogonal to the transfer direction 12 of the VCCD 2. That is, the transfer electrodes of the transfer unit 7 are equal on the read gate 6 side and on the side far from the read gate 6. Further, the surface areas of the transfer electrodes are made substantially equal in order to make the transfer charge amounts in the transfer sections 7 and 8 substantially equal.

[0007]

However, in the above-mentioned conventional configuration, the pitch of the unit pixels becomes shorter as the density becomes higher, and the area of the transfer portion is made equal to make the transfer charge amount equal. Then, the gate width of the read gate is narrowed, and there is a problem that the conductance when reading the signal charge from the photoelectric conversion element to the transfer unit is small. Therefore, signal charges are likely to remain in the photoelectric conversion element, and the afterimage characteristic is poor.

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 having improved afterimage characteristics.

[0009]

In order to achieve this object, the solid-state image pickup device of the present invention is configured such that a side of a transfer electrode of a transfer electrode that first enters after a signal charge passes through a read gate has a signal crossing side. It has a configuration that is not orthogonal to the charge transfer direction.

[0010]

With this structure, the width of the read gate can be widened even when the pitch of the unit pixel is small, so that the conductance of the read gate can be increased. As a result, when the signal charge is read from the photoelectric conversion element, the signal charge remaining in the photoelectric conversion element can be eliminated, and the afterimage characteristic can be improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of a main part of a solid-state imaging device according to an embodiment of the present invention. In FIG. 1, the same parts as those of the conventional example shown in FIG. Note that 11a is a boundary line between the transfer units 7 and 8. In the present embodiment, as shown in FIG. 1, by making the side of the transfer section 7 on the side of the read gate 6 longer and shortening the opposite side to form a trapezoidal shape, reading is performed even when the pitch 10 of the unit pixel becomes small. The width 9 of the gate 6 can be widened. That is, in this embodiment, the boundary line 11a is different from the conventional example shown in FIG.
Is not orthogonal to. In this way, the read gate 6
The afterimage characteristic can be improved by increasing the conductance of.

Further, when the transfer section 7 has a trapezoidal shape as in this embodiment, the areas of the transfer section 7 and the transfer section 8 can be easily made equal to each other, and the respective transfer capacities are different from those of the conventional example. There can be no configuration.

In this embodiment, the case where the shape of the transfer portion 7 is a trapezoid has been described, but the same effect can be obtained even when the shape of the transfer line 7 is a parallelogram in which the boundary line 11a is not orthogonal to the transfer direction 12.

A boundary line 11a between the transfer unit 7 and the transfer unit 8
The trapezoidal shape of the transfer portion 7 is determined by one side of the transfer electrode (not shown).

[0015]

As described above, according to the present invention, the side crossing the transfer portion of the transfer electrode of the transfer portion that first enters after the signal charge passes through the read gate is not orthogonal to the transfer direction of the signal charge. As a result, it is possible to realize an excellent solid-state image pickup device in which the afterimage characteristics are improved and the transfer capacity of each transfer unit is almost the same as the conventional one.

[Brief description of drawings]

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

FIG. 2 is a block diagram of a conventional interline transfer type CCD solid-state imaging device.

FIG. 3 is a plan view of a main part of a conventional solid-state imaging device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoelectric conversion element 6 Read gate 7 Transfer unit 8 Transfer unit 11a Boundary line (side crossing transfer unit) 12 Transfer direction

Claims (1)

[Claims] 1. A photoelectric conversion element for accumulating signal charges converted by photoelectric conversion, a plurality of transfer sections each having a transfer electrode for transferring the signal charges, and reading the signal charges from the photoelectric conversion elements to the transfer section. And a read gate for
A solid-state imaging device, wherein a side of a transfer electrode of a transfer unit that first enters the signal charge after passing through the read gate is not orthogonal to a transfer direction of the signal charge.