JPH07105865A - Image pickup device and method for operating it - Google Patents

Abstract

PURPOSE:To provide an image pickup device using a photoconductive film of an amorphous semiconductor which keeps an initial image plane of good quality and suppressing the image deterioration after a long-time use. CONSTITUTION:An ion-etched area 2 containing a scanning area and an non-ion etched area 3 are formed on a base 1, a conductive film 4, a positive hole injection arresting layer, a photoconductive layer 6 of amorphous semiconductor, and an electron beam landing layer are accumulated thereon, and the photoconductive film 6 is set in such a manner that it never reach the non-ion etched area 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device using an amorphous semiconductor for a photoconductive film and its operating method.

[0002]

2. Description of the Related Art As a conventional image pickup device using an amorphous semiconductor as a photoconductive film, for example, a photoconductive film made of an amorphous semiconductor mainly composed of a conductive film, a hole injection blocking layer and Se is formed on a substrate. A blocking-type image pickup tube including an image pickup tube target portion in which a film and a beam landing layer are sequentially deposited, an electron gun for emitting an electron beam, and a scanning electron beam generation portion having an electrode for focusing and deflecting the electron beam is provided. is there. Since such an image pickup tube has sensitivity to visible light, ultraviolet rays or X-rays, and has low afterimage and high resolution, it is used in various fields. Regarding the above-mentioned image pickup tube, for example, Japanese Patent Publication No.
No. -30382 and the National Conference of Television Society Proceedings (1982), pages 81-82. In addition, avalanche multiplication is performed by applying an electric field of about 0.8 to 2 megavolts / centimeter to a photoconductive film made of an amorphous semiconductor mainly composed of Se to operate, and a high sensitivity is achieved. Type imaging tube. Regarding the above-mentioned image pickup tube, for example, Technical Report 10 of the Television Society
Volume, N0.45, pp. 1-6, ED-'87 (Showa 62)
Year). As a means for improving the initial screen defect that occurs in these image pickup devices, for example, a method of subjecting the surface of the substrate to an ion etching treatment has been proposed (JP-A-1-192177).

[0003]

Since the photoconductive film of the image pickup device is amorphous, the image pickup device has a drawback in that when it is used for a long period of time, image deterioration is likely to occur due to changes with time such as volume shrinkage and crystallization. It was The volume contraction of the photoconductive film causes cracks in the photoconductive film or a thin film layer deposited on the photoconductive film for the purpose of blocking carrier injection or the like, which causes a screen defect. Further, if the amorphous material is crystallized, the electrical characteristics and the optical characteristics are changed, so that a screen defect also occurs. Due to these factors, the conventional image pickup device using the amorphous semiconductor for the photoconductive film has a problem that sufficient life characteristics cannot always be obtained when used for a long time.

It is an object of the present invention to maintain an image quality of an image pickup device using a photoconductive film made of an amorphous semiconductor, which is the same as that of a conventional one, which is obtained in the initial stage, and suppress the deterioration of the screen after long-term use. And

[0005]

The above-mentioned object is provided with a substrate, a conductive film provided on the substrate, and a photoconductive film at least a part of which is rectifying bonded to the conductive film and which is amorphous. An image pickup device comprising a photoelectric conversion unit and a scanning unit for reading out signal charges generated in the photoconductive film in time series, wherein an ion etching treatment region including the entire scanning region and ions are provided on the substrate. And a non-etched region, wherein at least a part of the photoconductive film reaches the untreated region of the substrate.

[0006]

In the image pickup tube using the amorphous semiconductor mainly composed of Se as the photoconductive film of the target portion of the image pickup tube, the inventors of the present invention have determined the life characteristics of the screen defect, that is, the screen defect, which occurs when used for a long time. As a result of the investigation, it was clarified that the crystallization that occurred at the substrate side interface of the photoconductive film and the crack of the photoconductive film were the main causes. Furthermore, as a result of detailed investigation of the relationship between these screen defects and the ion etching treatment of the substrate surface, which is a means for improving the initial screen defects, when the ion etching treatment is carried out, the local crystal of the photoconductive film is crystallized. It was clarified that the life characteristics deteriorate due to aging and cracking. Therefore, the substrate surface of the image pickup tube target portion is provided with an ion-etched treated region and a non-treated region that is not ion-etched, the treated region includes the entire scanning region, and the peripheral portion of the photoconductive film is the untreated region. As a result of the structure to reach, screen defects were less likely to occur both initially and when used for a long time.

Next, an example of a concrete embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic structural view showing an image pickup tube target portion in an image pickup apparatus of the present invention.
1A is a plan view of the target portion, and FIG. 1B is a sectional view. In the figure, reference numeral 1 denotes a substrate, which has a region 2 subjected to ion etching treatment and a region 3 not subjected to ion etching treatment on its surface. Reference numeral 4 is a conductive film, 5 is a hole injection blocking layer, 6 is a photoconductive film at least a part of which is composed of an amorphous semiconductor layer, 7 is an electron beam landing layer, broken line 8 is a line showing a scanning region, and broken line 8 The inside is scanned with an electron beam during use. Here, the structure in which the hole injection blocking layer 5 is formed between the conductive film 4 and the photoconductive layer 6 for the purpose of assisting the rectification property in which the current flows in only one direction is shown, but the sufficient rectification property is obtained. If so, the conductive film 4 and the photoconductive layer 6 may be brought into direct contact with each other. The image pickup tube target portion having the above structure,
The image pickup apparatus of the present invention can be obtained by combining with a scanning electron beam generating unit provided with an electron gun for emitting an electron beam and an electrode for focusing and deflecting the electron beam.

In FIG. 1, the ion-etched region 2 on the surface of the substrate 1 has a circular shape, but it does not have to be circular, and if the entire scanning region surrounded by the broken line 8 is covered, it has a quadrangle or an ellipse. The shape may be the same. What is important is that the entire scanning region 8 is included in the ion-etched region 2 and that at least a part of the photoconductive film 6 reaches the non-ion-etched region 3. is there. Although FIG. 1 shows a preferable structure in which the entire peripheral portion of the photoconductive film 6 reaches the region 3 which is not subjected to the ion etching treatment, at least a part of the photoconductive film 6 overlaps with the untreated region 3. Is effective. Here, the larger the overlapping area of the photoconductive film 6 and the region 3 not subjected to the ion etching treatment, the more preferable. Further, FIG. 1 shows a structure in which the conductive film 4 is interposed between the peripheral portion of the photoconductive film 6 and the region 3 of the substrate 1 which is not subjected to the ion etching treatment. The layer may be in direct contact with the substrate 1, or any one of the conductive film 4, the hole injection blocking layer 5 and the like, which exists between the amorphous layer in the photoconductive layer 6 and the substrate 1. Alternatively, a plurality of thin film layers may be interposed. Although FIG. 1 shows the case where the ion etching treatment is directly performed on the substrate 1, the conductive film 4
Or any of the thin film layers existing between the amorphous layer in the photoconductive film 6 such as the hole injection blocking layer 5 and the substrate 1 is deposited,
Ion etching treatment may be performed.

As the photoconductive film used in the present invention, there is an amorphous semiconductor mainly composed of Se. In the amorphous semiconductor mainly composed of amorphous Se, a charge multiplication phenomenon is observed when an electric field of about 0.8 to 2 megavolt / cm is applied. It is a material having a so-called avalanche multiplication function. When this material is used as a photoconductive film and further operated by applying an electric field such that the avalanche multiplication occurs,
The sensitivity can be increased. The present invention was particularly effective when used under high electric field conditions as described above. Also,
The material of the photoconductive film may be amorphous, which mainly contains elements such as Te and Si in addition to Se, and As, Li,
Elements such as F and H may be added and used. For example, the addition of an element such as Te to Se to obtain a red sensitizing effect is disclosed in JP-A-49-24619, but all of these photoconductive films can be used. Further, the photoconductive film may be composed of amorphous layers made of different materials. Further, it is not necessary that all of the photoconductive film is made of an amorphous layer, and at least a part of the photoconductive film is provided for the purpose of obtaining a red sensitizing effect.
It may be a polycrystalline semiconductor layer made of a material such as Te.

As a method of forming a region subjected to ion etching treatment and a region not subjected to treatment on the substrate, for example, a high frequency sputtering apparatus shown in FIG. 6 is used, a substrate 603 is set on a negative electrode 601 in the apparatus, and a mask is used. After covering the peripheral portion of the substrate 603 with 604, Ar, H
It is realized by performing high frequency discharge in an atmosphere of an inert gas such as e or N ₂ . The atmosphere for high frequency discharge is Ar, He,
Inert gas such as N ₂ or other H ₂ O, O ₂ etc. 1
One or more kinds of gases may be mixed and used. In this case, it is important to adjust the mask 604 to form a treated region exposed to discharge ions and a non-treated region on the substrate 603, and at least the entire scanning region is within the treated region. And that at least a part of the region where the photoconductive film is deposited reaches the untreated region. Further, when the above method is used, if the surface of the substrate 603 and the mask 604 are brought into contact with each other, dust adheres to the surface of the substrate 603 and causes a screen defect, which is not preferable. If the distance between the two is too large, the effect of the mask will be lost. Therefore,
The distance between them is preferably 0.1 mm or more and 10 mm or less.
Furthermore, it is more preferable that the distance between the two is 0.2 mm or more and 10 mm or less, because the boundary between the treated region and the untreated region becomes gentle and there is no possibility of crystallization at this portion. Further, when the above ion etching treatment is performed, part of the material included in the mask 604 is partially removed from the substrate 603.
Therefore, the material of the mask 604 is preferably a material that is not easily ion-etched in a discharge atmosphere or a material included in the surface to be ion-etched, and the same material as the surface to be ion-etched is preferable. More preferable. Although the case where the high frequency sputtering device is used is described here, even if a magnetron sputtering device or a plasma asher device is used,
A similar ion etching process can be performed.

As another method, for example, an ion beam irradiation apparatus shown in FIG. 7 is used, and a substrate holder 7 in the apparatus is used.
01, a substrate 704 is placed on the substrate 101, and an inert gas such as Ar, He, N ₂ or the like, or a mixed gas of any one or more kinds of H ₂ O, O ₂ or the like is ion beam source 702. It is realized by irradiating as 703. In this case, it is important to control the ion beam source 702 so that at least a part of the region on the substrate 704 where the photoconductive film is deposited is not irradiated with the ion beam 703, and at least the scanning region. That is, the ion beam 703 is applied so as to cover the entire surface. When the ion beam irradiation method as described above is used, the substrate is not covered with a mask during the ion etching process, so that there is an advantage that dust is less likely to adhere to the substrate surface as compared with the case where the high frequency sputtering method is used. .

Table 1 below shows an example of the screen defect reducing effect in the image pickup tube in which the present invention is implemented.

[0013]

[Table 1]

In the table, a indicates a case where a glass substrate not subjected to ion etching treatment is used, b indicates a case where a glass substrate subjected to ion etching treatment on the entire surface is used, and c indicates a case where the present invention is carried out. Forming a treated region that has been subjected to ion etching and a non-treated region that is not treated,
In the case where the entire scanning area is included in the processing area and the entire peripheral portion of the photoconductive film reaches the non-processing area, an initial screen defect occurs in the image pickup tube and crystallization after continuous operation for 1000 hours. And shows the occurrence of screen defects due to cracks. By implementing the present invention, it has been clarified that the screen defect does not occur even in the initial stage, and the screen defect does not easily occur even when used for a long time.

The image pickup tube has been described above as an example of the embodiment of the present invention. However, in the present invention, the scanning unit has a plurality of electron beam emission sources, and the electron beam emission electron is emitted in the electron beam emission sources. The image pickup device may have a means for changing the beam source with time, and a plurality of pixel electrodes rectifying and joined to the photoconductive film and a time-changing electrical contact with the pixel electrodes may be provided. It may be a solid-state imaging device consisting of possible scanning electronics or a light-receiving device such as a line sensor. The present invention is also effective for a solid-state imaging device using an IC substrate whose substrate has a scanning function.

[0016]

Embodiments of the present invention will now be described with reference to the drawings. 2 is a schematic view showing a first embodiment of an image pickup tube target section in an image pickup apparatus of the present invention, FIG. 3 is a schematic view showing a second embodiment of the image pickup tube target section, and FIG. 4 is a diagram showing an image pickup apparatus according to the present invention. FIG. 5 is a structural diagram of a licensor shown as a third embodiment, and FIG. 5 is a fourth embodiment showing a solid-state image pickup device according to the present invention.

First Embodiment In FIG. 2 showing an image pickup tube target portion in an image pickup apparatus of the present invention, (a) is a plan view and (b) is a sectional view.
A region 202 subjected to ion etching treatment and a region 20 not subjected to ion etching treatment were performed on the translucent glass substrate 201 having a diameter of 26 mmφ to which the electrode pins 209 are welded by using the high frequency sputtering device as shown in FIG.
3 and 3 are formed. As shown in FIG. 2, on the substrate 201, a transparent conductive film 204 made of In ₂ O ₃ having a film thickness of 20 nm and a positive electrode made of CeO _{2 having a} film thickness of 10 nm are formed in a region surrounding the scanning region 208 and the electrode pins 209. Hole injection blocking layer 205
Are sequentially deposited by a vacuum vapor deposition method using a vapor deposition mask. Here, the region 202 subjected to the ion etching treatment
Is controlled to a range slightly larger than the deposition region of the conductive film 204 and the hole injection blocking layer 205 by controlling the mask used during the ion etching process. Further, a photoconductive film 206 made of amorphous Se and having a diameter of 20 mmφ and a film thickness of 2 μm is deposited on the hole injection layer 205 by a vacuum deposition method using a deposition mask. Sb ₂ S ₃ was vapor-deposited thereon in a N ₂ gas atmosphere with a pressure of 0.2 Torr using a vapor deposition mask, and porous Sb ₂ S ₃ having a diameter of 20 mmφ and a film thickness of 100 nm was formed.
An electron beam landing layer 207 is formed to obtain an image pickup tube target. The obtained tube target,
The scanning electron beam generator including an electron gun for emitting an electron beam and an electrode for focusing and deflecting the electron beam is provided with an In
After crimping through, the inside of the tube is vacuum-sealed to obtain an image pickup tube.

Since the conductive layer area is made as small as possible, this embodiment has an advantage that the parasitic capacitance is reduced and a high SN ratio can be obtained. Further, in this embodiment, the area where the region not subjected to the ion etching treatment and the photoconductive film overlap is
This is an extremely preferable structure for an image pickup tube target of this size, which is close to the maximum value and has good life characteristics.

Second Embodiment In FIG. 3 showing a second embodiment of the target portion of the above-mentioned image pickup tube, (a) is a plan view and (b) is a sectional view. On transparent glass substrate 301, diameter 24mmφ and film thickness 500n
A transparent conductive film 304 made of Sn ₂ O _{3 of} m is deposited by the CVD method. On the substrate on which the conductive film 304 is deposited, using an ion beam irradiation device as shown in FIG.
Ion-etched area 302 with a diameter of 17 mm
And a region 303 not to be ion-etched are formed. A film with a diameter of 20 mm and a film thickness of 15
hole injection blocking layer 305 made of CeO _{2 of} m, and Cd provided for red sensitization with a diameter of 20 mmφ and a film thickness of 1 μm.
Se polycrystalline layer 306 and Se amorphous layer 30 for causing avalanche multiplication with a diameter of 20 mm and a film thickness of 2 μm.
A photoconductive film 308 composed of 7 is sequentially deposited by a vacuum deposition method using a deposition mask. Sb ₂ S ₃ was vapor-deposited thereon in a N ₂ gas atmosphere with a pressure of 0.2 Torr using a vapor deposition mask, and porous Sb ₂ having a diameter of 20 mmφ and a film thickness of 100 nmφ.
An electron beam landing layer 309 made of S ₃ is formed to obtain an image pickup tube target. The obtained image pickup tube target is pressure-bonded to the scanning electron beam generator via In, and the inside of the tube is vacuum-sealed to obtain an image pickup tube.

Third Embodiment In FIG. 4 showing a line sensor as a third embodiment of the image pickup apparatus of the present invention, (a) is a partial plan view, (b) is a partial plan view.
FIG. 4 is a sectional view taken along the line AA ′ in (a) above. First,
A strip-shaped ion-etched region 402 and a non-ion-etched region 4 were formed on the transparent glass substrate 401 by the same high-frequency sputtering method as in the first embodiment.
And 03. Then, in the ion-etched region 402 on the glass substrate 401, a light-transmitting conductive film 404 made of Al and having a film thickness of 10 nm and a hole injection blocking layer 405 made of CeO ₂ having a film thickness of 20 nm are formed by a vacuum deposition method. The strips are deposited in sequence. Then, a photoconductive film 406 made of a Se—Te based amorphous layer containing Te 5% with a film thickness of 2 μm is formed in a region larger than the ion-etched region 402.
Deposited in strips by vacuum evaporation. On top of that, a film thickness of 50
After depositing nm of Au in strip shape by vacuum evaporation method,
Stripe-shaped pixel electrodes 407 formed by photoetching
To form. In this case, since Au forms a rectifying junction with the Se—Te-based amorphous photoconductive film, it is not necessary to insert an electron injection blocking layer for enhancing the rectifying property between the two. Further, the pixel electrode 407 is connected to a scanning electronic circuit for time-sequentially reading out the signal charges generated in the photoconductive film by a means such as bonding to obtain a licensor according to the present invention.

Compared with the first and second embodiments, this embodiment has the advantages that it has no vacuum portion, is small and lightweight, and is easy to handle. Further, since Te is added to the amorphous Se photoconductive film, the red sensitivity is higher than that in the first embodiment. Further, in the second embodiment, the photoconductive film has a two-layer structure for red sensitization, and there is a possibility that the electrical characteristics may deteriorate due to a rectifying junction or the like at the hetero interface between the two. In the embodiment, there is no such fear because it has a single layer structure.

Fourth Embodiment In FIG. 5 showing a fourth embodiment of the solid-state image pickup device according to the present invention, (a) is a plan view and (b) is a sectional view per pixel of a scanning unit provided in a scanning region. Indicates. The source electrode 5 is formed in the scanning region 514 on the substrate 501 made of single crystal Si.
04, drain electrode 505, gate electrode 506, pixel electrode 507, and insulating layer 508 are two-dimensionally integrated MOS-
The IC scanning unit 513 is formed. An electron injection blocking layer 509 made of Sb ₂ S ₃ having a film thickness of 60 nm is deposited thereon by a vacuum evaporation method, and then the region 502 is ion-etched by a high frequency sputtering method as shown in FIG. On top of that, a photoconductive film 510 of Se—As based amorphous semiconductor containing 2% As of 2 μm thickness, a hole injection blocking layer 511 of CeO _{2 of} 10 nm thickness, and a 10 nm thickness of
And the conductive layer 512 are deposited on the region 515 to obtain the solid-state imaging device according to the present invention.

The present embodiment has the advantage that it is small in size, light in weight, and easy to handle without having a vacuum portion, as compared with the image pickup apparatus of the first and second embodiments. Further, by containing 2% of As, the heat resistance of the photoconductive film made of an amorphous semiconductor mainly composed of Se is improved.

In each of the above-described embodiments, when an amorphous layer mainly composed of Se in the photoconductive film is operated by applying an electric field of about 0.8 to 2 megavolts / centimeter, the amorphous film in the photoconductive film is operated. The avalanche multiplication phenomenon occurs and the sensitivity can be increased. The present invention is particularly effective when operated under such a severe electric field condition.

[0025]

As described above, in the image pickup device and the method of operating the same according to the present invention, at least a part of the substrate, the conductive film provided on the substrate, and the rectifying junction with the conductive film is amorphous. In an imaging device including a photoelectric conversion unit including a photoconductive film formed by: and a scanning unit configured to read out signal charges generated in the photoconductive film in time series, the entire scanning region is formed on the substrate. Since the photoconductive film has an ion-etching treated area and an ion-etching untreated area, and at least a part of the photoconductive film reaches the untreated area of the substrate, the initial quality is the same as the conventional one. It has the effects of maintaining a stable screen state and suppressing deterioration of the screen when used for a long time. This effect is particularly effective when an amorphous semiconductor containing Se as a main material is used as the photoconductive film and a high voltage is applied to the photoconductive film to cause avalanche multiplication to operate.

[Brief description of drawings]

FIG. 1 is a basic structural view of an image pickup tube target portion in an image pickup apparatus of the present invention, in which (a) is a plan view and (b) is a sectional view.

2A and 2B are structural views showing a first embodiment of an image pickup tube target portion in an image pickup apparatus of the present invention, in which FIG. 2A is a plan view and FIG.
Is a sectional view.

3A and 3B are structural views showing a second embodiment of the image pickup tube target portion, wherein FIG. 3A is a plan view and FIG. 3B is a sectional view.

4A and 4B are structural views of a licensor shown as a third embodiment of the image pickup device according to the present invention, in which FIG. 4A is a partial plan view and FIG.
FIG. 6 is a sectional view taken along line AA ′.

5A and 5B are a fourth embodiment showing a solid-state image pickup device according to the present invention, FIG. 5A is a plan view, and FIG. 5B is a sectional view per pixel in a scanning region.

FIG. 6 is a schematic view showing a high frequency sputtering apparatus for ion etching used in the present invention.

FIG. 7 is a schematic view showing an ion beam irradiation apparatus for ion etching used in the present invention.

[Explanation of symbols]

1, 201, 301, 401, 501 ... Substrate 2, 202, 302, 402, 502 ... Ion etching treated region 3, 203, 303, 403, 503 ... Ion etching non-treated region 4, 204, 304, 404, 512 ... Conductive film 6,206, 308, 406, 510 ... Photoconductive film 8, 208, 310, 514 ... Scan area 407, 507 ... Pixel electrode

Front page continuation (72) Inventor Yasushi Nakano 1-280 Higashi Koigokubo, Kokubunji, Tokyo Inside Central Research Laboratory, Hitachi, Ltd. (72) Kazutaka Tsuji 1-280 Higashi Koikeku, Kokubunji, Tokyo Hitachi Central Research Co., Ltd. (72) Inventor Setsu Kubota 1-10-11 Kinuta, Setagaya-ku, Tokyo Broadcasting Technology Research Institute, Japan Broadcasting Corporation (72) Inventor Shiro Suzuki 1-10-11 Kinuta, Setagaya-ku, Tokyo Broadcasting Association of Japan Inside the technical laboratory

Claims (7)

[Claims] 1. A photoelectric conversion part comprising a substrate, a conductive film provided on the substrate, a photoconductive film which is rectifyingly joined to the conductive film and at least a part of which is amorphous, and the photoconductive film. An imaging device comprising a scanning unit for reading out signal charges generated in a film in time series, wherein an ion etching treatment region including the entire scanning region and an ion etching non-treatment region are provided on the substrate. An imaging device in which at least a part of the photoconductive film reaches the unprocessed region of the substrate. 2. The scanning unit includes an electron gun for emitting an electron beam, and an electrode for focusing and deflecting the electron beam.
The scanning electron beam generator is a scanning electron beam generator.
The imaging device described. 3. The scanning section comprises at least a plurality of pixel electrodes rectifyingly joined to the photoconductive film and a scanning electronic circuit capable of making a time-varying electrical contact with the pixel electrodes. The imaging device according to claim 1, further comprising: 4. The image pickup apparatus according to claim 1, wherein the scanning unit is present inside the substrate. 5. The image pickup device according to claim 1, wherein at least a part of the photoconductive film is made of a layer having an avalanche multiplication function. 6. The photoconductive film according to claim 1, wherein at least a part of the photoconductive film is composed of an amorphous layer containing Se as a main component.
Alternatively, the imaging device according to claim 3 or claim 5. 7. An image pickup device using the image pickup device according to any one of claims 1 to 6, wherein at least part of the photoconductive film is operated in an electric field such that avalanche multiplication of charges occurs. How the device works.