JPS5985187A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To obtain a solid-state image pickup device with high resolution by impressing respectively a voltage with a charge storage section and a pair of electrodes provided on a photo conductor having a rectifying characteristic, splitting the electrode formed at unit element into two for signal readout. CONSTITUTION:A voltage is impressed to one of electrodes 18, 19, e.g., 18 only or the electrode is brought into a ground potential at the 1st frame period, and the other electrode 19 is floated. A reading pulse is impressed to a gate electrode 14 in this state. When an incident light 20 enters the photo conductor 17, electron and positive hole pairs are produced, the electrons are collected on the electrode 16 and the positive holes are collected on the electrode 18 and the diode potential is decreased. In this case, since the other electrode 19 is floated, the incident light 20 to this part is not used at all, and only the part corresponding to the 18 of the electrode 16 becomes one picture element. At the next frame period, a voltage is impressed to the other electrode 19 or the electrode is connected to ground, the other electrode 18 is floated, then the unit picture element corresponding to the electrode is doubled for attaining high resolution.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a solid-state imaging device, and particularly relates to a high-resolution solid-state imaging device in which a photoconductor is formed as a light receiving element on a semiconductor substrate having a charge transfer function. be.

[Technical background of the invention and its problems]

Conventionally, there are solid-state imaging devices that use a photodiode as a photodetector and a charge transfer device (hereinafter referred to as CCD) that transfers the charge accumulated in the photodiode, but most of these devices have a photodiode and a charge transfer device that transfers the charge accumulated in the photodiode. Since it is necessary to configure both parts on the same substrate surface, the light utilization efficiency per unit area has been 20 to 30% at most. Furthermore, if an overflow drain is formed to suppress blooming, the light utilization efficiency will further decrease. In order to eliminate this problem, a solid-state imaging device has been proposed in which a photoconductor has photosensitivity instead of a photodiode in the photodetector section and is combined with a CCD.

Such a solid-state imaging device includes an insulating layer provided on a semiconductor substrate so as to partially have an opening, and a first electrode that is electrically coupled to a charge storage section through an opening for each unit element. is formed on an insulating layer.

Therefore, the light utilization rate can be set to 50 to 75%.

However, color cameras are currently becoming smaller in size from 2/3 inch to 1/2 inch. In this case, in order to obtain a resolution high enough to be used for broadcasting, approximately 800 picture elements horizontally and approximately 500 picture elements vertically, that is, approximately 400,000 picture elements on the entire surface, are required. Therefore, the size of the unit picture element is 2/3
Calculated in terms of 11 μm horizontally and 13 μm vertically.

If a diode section, a read gate section, and a transfer section are provided in a unit pixel of this size as in an interline transfer type CCD, it is impossible to manufacture using current integrated circuit technology. In particular, when the width of the transfer section is narrower than 4 to 5 μm, it becomes a narrow channel.
) effect makes it impossible to transfer a sufficient amount of charge,
The width cannot be made smaller than 5 μm.

[Object of the Invention] The present invention has been made in view of the above-mentioned problems, and involves applying a voltage alternately between a pair of second electrodes provided on a photoconductor having rectifying characteristics and a charge storage section. However, it is an object of the present invention to provide a high-resolution solid-state imaging device by further dividing the first electrode formed for each unit element into two and reading out signals.

[Summary of the invention]

That is, the present invention provides a semiconductor substrate having a charge transfer section for transferring the charges accumulated in the charge accumulation section of the charge accumulation section, and a semiconductor substrate provided with an opening in a part of the charge accumulation section. a first electrode formed for each unit element on the insulating layer so as to be electrically coupled to the charge storage part through the opening, and a first electrode formed to cover the first electrode and the insulating layer. a pair of transparent electrodes arranged in a comb-like shape as a second electrode, and each comb-teeth of the transparent electrode is provided in a region corresponding to the first electrode;
A voltage is alternately applied between the pair of transparent electrodes and the charge storage section, so that signals from regions obtained by further dividing the first electrode region formed for each unit element into two can be read out alternately. The solid-state imaging device is characterized in that the comb teeth are perpendicular to the scanning line direction, and the vertical G, B, In this embodiment, R, G, Cy, and Mg stripe filters are combined to obtain a color output signal.

[Embodiments of the invention] Next, each embodiment of the present invention will be described according to the drawings.

Figures 1(a) and (b) show the cross-sectional structure of one unit of each embodiment, and Figure 1(a) shows the case where the charge storage section is a diode and the charge transfer section is a surface channel CCD. However, the present invention is not limited to this, and as shown in FIG. 1(b), for example, the charge storage section may form a potential well (8) using the gate electrode (9), and the charge transfer section may form a potential well (8). It may also be a buried channel CCD or BBD.

That is, first, an n+ type region (11) is formed on a P type semiconductor substrate (10).
) and provide a diode. (12) is a transfer gate electrode for charge transfer, which allows the half-substrate (
A depletion layer (13) is formed in 10). (14) is a first gate electrode for reading the charge accumulated in the diode (11) into the transfer section (13), and (15) is an insulating layer. The first electrode (16) electrically coupled to the diode (11) and separated into each picture element portion is a photoconductor layer. A pair of second electrodes (18) and (19) are formed corresponding to the first electrode (16) constituting a picture element, and a voltage is alternately applied to each of them for a predetermined period of time. (2
0) is the incident light.

Figure 2 shows the second electrode for the first electrode (16'), (16'').
An example of the overall configuration when the electrodes (18) and (19) are arranged two-dimensionally is shown. That is, the second electrode (18) (19)
A pair of transparent electrodes arranged in a comb-like shape are used as the electrodes.

Next, the reading operation of each embodiment will be explained using FIGS. 1 and 2.

During the first frame period, one of the second electrodes (18) and (19), for example, only (18) is applied with a voltage or set to the ground potential, while the other (19) is left floating. In this state, the first gate electrode (14) is left floating. ) is read pulse (VCH
), the potential of the diode (11) becomes (
VCH-VT). Here (VT) is the threshold voltage.

When the incident light (20) enters the photoconductor (17), it creates electron-hole pairs, and the electrons are collected at the first electrode (16);
The holes are collected at the second electrode (18), lowering the diode potential. In this case, since the other side of the second electrode (19) is floating, the incident light (20) on this part
is not used at all, and only the portion on the first electrode (16) corresponding to one side (18) of the second electrode becomes one picture element. In the case of the interlaced method, the optical signal obtained in this way is read out in two fields to form one frame, and in the next frame period, a voltage is applied only to the other side of the second electrode (19) or connected to the ground potential, If one of the second electrodes (18) is made floating, high-resolution operation with double the number of unit pixels corresponding to the first electrode becomes possible.

According to each example, in order to obtain approximately 800 pixels horizontally, 2
The unit picture element is approximately 22 μ horizontally in 3 inches, and can be easily manufactured using current integrated circuit technology, and its industrial value is extremely large.

It is also possible to use the solid-state imaging device of the embodiment for color imaging; for example, a pair of second electrodes (18) (19)
G, B. in the vertical direction corresponding to only one of them. repeating R, or G. Cy. It goes without saying that color signals that are easy to process can be obtained by combining Mg repeating color stripe filters.

Further, one or more storage sections having the same number of unit elements are formed adjacent to the same substrate as the solid-state imaging device of the embodiment, so that the area is 1/60 to 1/1.
Of course, it is also possible to read signals every 20 seconds and synthesize them as a standard television signal corresponding to 1/30 second accumulation.

Next, an example of a method for manufacturing the solid-state imaging plate of the embodiment will be described. First, an n+ type region (11) is formed in a p-type Si substrate (10) by an ion implantation method. Next, a transfer gate electrode (1
After forming and insulating the first gate electrode (2), the first gate electrode (1
4) Form. Next, SiO2 is formed as an insulating layer (15) by the CVD method, and a contact hole is formed so as to be located in the n+ type region (11).
The first electrode (16) is formed by etching and separated into unit picture elements.

α-
Form 1 to 4μ of Si:H, and then add α-Si as a P layer.
Form C:H at 100-500A. Furthermore, the second
Transparent electrodes as electrodes (18) and (19) were used as I. T. O(
5 using IndumTin Oxide) target.
After forming by 00 to 2000A magnetron sputter deposition method, the fruit is etched into a comb shape as shown in FIG. 2, thereby constructing a solid-state imaging device.

The embodiments and manufacturing methods described above are representative, and it goes without saying that various other structures and manufacturing methods can be considered.

〔Effect of the invention〕

As described above, according to the present invention, a voltage is alternately applied between the pair of second electrodes provided on the photoconductor having rectifying characteristics and the charge storage portion, and the second electrodes formed for each unit element are Since a high-resolution solid-state imaging device can be obtained by further dividing one electrode into two and reading signals, its industrial value is extremely large.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are diagrams showing each embodiment of the present invention,
Figures 1 (a) and (b) are cross-sectional views of one unit of each example, and Figures 2 (a) and (b) are explanatory diagrams showing the relationship between the first electrode and the second electrode in each example. be. 10...P type semiconductor substrate 11...n+ type region 12
...Transfer gate electrode 13...Depletion layer 14...First gate electrode 15...Insulating layer 16, 16', 16''
...First electrode 17...Photoconductor layer 18, 19...
Second electrode 20...Incoming light agent Patent attorney Kazuo Inoue Figure 1 ((1) (b> Figure 2 (Q)

Claims (3)

[Claims] (1) A semiconductor substrate having a charge storage section and a charge transfer section that transfers the charges accumulated in the charge storage section, and a semiconductor substrate provided on the semiconductor substrate so as to have an opening in a part of the charge storage section. a first electrode formed for each unit element on the insulating layer so as to be electrically coupled to the charge storage section through the opening, and the first electrode and the insulating layer It consists of a photoconductor having rectifying properties formed to cover the photoconductor, and a pair of transparent electrodes arranged in a comb-like shape as a second electrode formed on the photoconductor, and each of the above-mentioned Comb teeth of each of the pair of transparent electrodes are provided in a corresponding area on one electrode, and a voltage is alternately applied between the pair of transparent electrodes and the charge storage section, and each of the unit elements is The area of the first electrode formed in
A solid-state imaging device characterized in that signals from divided regions can be read out alternately. (2) The solid-state imaging device according to claim 1, wherein the comb teeth are perpendicular to the scanning line direction. (3) G in the vertical direction corresponding to only one of the pair of comb-shaped transparent electrodes. B. R or G. Cy. 2. The solid-state imaging device according to claim 1, wherein a color output signal is obtained by combining Mg stripe filters.