JPH08116403A - Image sensor with light source - Google Patents

Abstract

PURPOSE: To obtain the inexpensive image sensor having light source with thin profile and a subminiature size by forming a thin film light emitting element onto a transparent board and covering the side face of the transparent board with an optical reflecting body reflecting a light. CONSTITUTION: A solid-state image pickup element 10 receiving a reflected light of an original 28 and a read drive circuit 20 of the solid-state image pickup element 10 are formed on a board 1. Furthermore, thin film light emitting elements 30 emitting the original 28 are formed on the transparent board 21 in a line. Then an optical reflection body 29 such as an aluminum is provided at least too one side of the transparent board 21. Then the board 21 of the thin profile light emitting elements 30 is fixed to a side face of the board 1 at the side of the solid-state image pickup element 10 so that the both are almost mated. Then a transparent thin plate 32 is integrated (adhered or molded) onto the solid-state image pickup elements 10 and the transparent board 21 with a transparent adhesives 27 or the like. Thus, a read original face is emitted efficiently. Furthermore, an organic EL film acts like a face light source, emission without unevenness is attained without the need for a light diffusion plate or a lens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image sensor with a light source used for a facsimile or the like.

[0002]

2. Description of the Related Art In recent years, facsimiles have been required to be smaller, lighter, and cheaper in accordance with the spread thereof.
Image sensors used in facsimiles and the like are roughly classified into three types: non-contact type, contact type, and perfect contact type.

The non-contact type using a charge coupled device (CCD) has already been established, and L using a silicon wafer is used.
It is advantageous in terms of price because it can be produced by the SI manufacturing process and the CCD chip can be small, but since the original is projected on the CCD through the reduction lens system, there are two other methods for downsizing and weight reduction. Inferior to.

Further, the contact type image sensor has a merit that it is relatively easy to miniaturize since it does not need a reduction optical system and is gradually gaining acceptance in the market, but its rather high price hinders its popularization. It is in the state of being. Further, since the original is projected on the solid-state image pickup device using the SELFOC lens array and a light emitting diode (LED) array is used as a light source, a certain width and thickness are required (up to 15 mm).

On the other hand, the perfect contact image sensor can be further downsized as compared with the contact image sensor.
Since it is unnecessary to adjust the optical positions of the SELFOC lens array and the image sensor, the assembly process can be simplified easily. However, as in the contact image sensor, the thickness of the LED is still necessary. In addition, since the perfect contact image sensor needs to project light onto the original from the back side of the substrate on which the solid-state image sensor is arranged, it is necessary to form the solid-state image sensor on the transparent substrate, which is formed on the silicon wafer. It has been difficult to form a solid-state image sensor structure for a solid-state image sensor formed on a substrate that does not transmit light, such as a CCD or an alumina substrate.

A conventional example will be described below with reference to the drawings.
FIG. 7 is an explanatory view of a conventional example, and FIG. 7A is an explanation of a conventional contact image sensor. In FIG. 7A, the substrate 1 on which the LED house 42, the SELFOC lens array 43, and the solid-state image sensor are mounted is provided in the housing 41. Also, the LED installed in the LED house
Since it is a point light source, light is homogenized using a light diffusion plate such as frosted glass or a lens. Therefore, it is necessary to keep a distance from the document surface.

In this contact type image sensor, the light emitted from the LED house 42 is reflected by a document (not shown) on the housing 41, and the reflected light passes through the SELFOC lens array 43 and is solid on the substrate 1. It is input to the image sensor.

Such a contact type image sensor is shown in FIG.
(A) As shown by the arrow at the bottom, a certain width and thickness are required. FIG. 7B is a description of a conventional perfect contact type image sensor, in which the substrate 1 on which the solid-state image sensor 10 is mounted is provided on the upper surface of the housing 41, and the substrate 1 transmits light. A slit 40 for doing this is provided. An LED house 42 is provided on the lower surface of the housing 41. In this perfect contact type image sensor, the light emitted from the LED house passes through a slit 40 for transmitting the light provided on the substrate 1 and is reflected by a document (not shown), and the reflected light is reflected by the solid-state image sensor 10. It is input.

This perfect contact type image sensor is shown in FIG.
(B) The thickness of the LED house is required as indicated by the upper and lower arrows at the bottom.

[0010]

SUMMARY OF THE INVENTION The above-mentioned conventional devices have the following problems. Since the non-contact type image sensor projects the original document onto the CCD through the reduction lens system, the size and weight cannot be reduced. Further, since the contact type image sensor has an LED house as a light source, it cannot be downsized to a certain extent. Further, the perfect contact type image sensor requires the thickness of the LED house.

As described above, it has been found that what limits the size of the image sensor is an optical system such as a lens or a light source. In other words, it is necessary to reduce the size of the optical system in order to further reduce the size of the image sensor. Further, these optical systems occupy a ratio equal to or higher than that of the solid-state image pickup device main body from the viewpoint of manufacturing cost, and it can be said that the cost reduction of the optical system is very important for lowering the price.

An object of the present invention is to realize an image sensor with a light source which is thin, ultra-compact and inexpensive.

[0013]

In order to achieve the above object, the present invention is configured as follows. FIG. 1 is a configuration diagram of a first embodiment of the present invention, and FIG. 6 is a configuration diagram of a second embodiment of the present invention. In FIG. 1, a solid-state image sensor 10 to which reflected light of a document 28 is input and a reading drive circuit 20 of the solid-state image sensor 10 are formed on a substrate 1. Further, a thin film light emitting element 30 for irradiating a document 28 with line emission is formed on a transparent substrate 21 (lower surface in FIG. 1) having a thickness substantially the same as the substrate 1, and at least one side surface of the transparent substrate 21 is formed. A light reflector 29 such as aluminum (Al) is provided. Next, the substrate 21 of the thin-film light emitting device 30 is fixed to the side surface of the substrate 1 on the solid-state image pickup device 10 side so that they are substantially flush with each other. Further, the transparent thin plate 32 is integrated (bonded or molded) on the solid-state imaging device 10 and the transparent substrate 21 with the transparent adhesive 27 or the like.

Further, as shown in FIG. 6, the solid-state image pickup device 1
0 is formed on the transparent substrate 1 through the light shielding layer 31, a window 33 is provided in the light shielding layer 31 of the substrate 1, and the transparent substrate 21 of the thin film light emitting element 30 is provided on the lower surface of the substrate 1 provided with the window 33. Close the illuminated surface. Furthermore, the solid-state image sensor 10, the window 33
The transparent thin plate 32 is integrated with the transparent adhesive 27 or the like.

[0015]

The operation of the present invention based on the above configuration will be described. The light emitted from the thin film light emitting device 30 of FIG.
1 and the transparent thin plate 32 are projected onto the original 28, and the reflected light from the original 28 is input to the solid-state imaging device 10 through the transparent thin plate 32 and photoelectrically converted by the solid-state imaging device 10. This photoelectrically converted output is input to the reading drive circuit 20, and a signal corresponding to the lightness and darkness of the original is obtained from the reading drive circuit 20.

As described above, the thin film light emitting device 30 can efficiently irradiate the original 28 with the light reflector 29.
Since the thin film light emitting element 30 uses, for example, a thin film planar organic electroluminescence (hereinafter referred to as EL) element, it can be formed flat on the transparent substrate 21. Therefore, the transparent substrate 21 and the substrate 1 of the solid-state imaging device 10 can be fixed so as to be substantially flush with each other.
It is possible to obtain an image sensor with a light source that is ultra-compact and inexpensive.

Light emitted from the thin film light emitting device 30 of FIG. 6 is transmitted through the transparent substrate 21, the substrate 1 and the window 3 of the light shielding layer 31.
3. The light is projected onto the original 28 through the transparent thin plate 32, and the reflected light from the original 28 is input to the solid-state image sensor 10 through the transparent thin plate 32 and photoelectrically converted by the solid-state image sensor 10. As a result, a signal corresponding to the shading of the original 28 is obtained.

Since the thin film light emitting device 30 is composed of an organic EL device, it can be installed flat on the transparent substrate 21. Therefore, even if the substrate 1 and the transparent substrate 21 are overlapped with each other, it can be made thin, and the original is irradiated through the window 33 opened in the light shielding layer 31 in contact with the solid-state image sensor 10, so that the resolution of the image sensor is improved. be able to.

[0019]

【Example】

[Description of First Embodiment of the Present Invention] A first embodiment of the present invention will be described with reference to FIGS. 1 is a configuration diagram of a first embodiment of the present invention, FIG. 2 is an explanatory diagram of a phototransistor, FIGS. 3 and 4 are explanatory diagrams of a solid-state imaging device forming process, and FIG. 5 is an explanatory diagram of a thin-film light emitting device forming process. .

FIG. 1 shows the configuration of an image sensor with a light source, which will be described below. The solid-state image sensor 10 and the read drive circuit 20 for the solid-state image sensor 10 are formed on the substrate 1. In addition, a thin film light emitting device 30 is formed on a transparent substrate 21 having a thickness approximately the same as the substrate 1, and the side surface of the transparent substrate 21 is a thin film, a thick film or a metal foil that reflects light such as Al. Cover with a reflector 29.

Next, a transparent thin plate 32, which is a thin glass plate having a thickness of 50 to 200 μm, is attached to the upper surfaces of the solid-state image pickup device 10 and the transparent substrate 21 by a transparent adhesive such as an epoxy adhesive or an ultraviolet curing adhesive. The adhesive 27 is used for adhesion. In this case, the original 28 to be read comes into contact with the transparent thin plate 32.

FIG. 2 shows a photo used in the solid-state image sensor 10.
It is explanatory drawing of a transistor. In FIG. 2, 1 is a substrate
And, for example, glass substrate, quartz substrate, ceramics
(Al ₂O₃), Silicon substrate (polycrystal or single crystal), etc.
Is. 2 is an insulating film, and when the substrate 1 is a silicon substrate
If so, it can be formed using a thermal oxidation process. 3 is an active layer,
4 is a gate insulating film, 5 is a gate electrode, 6 is an interlayer insulating film,
7 is a metal wiring electrode, 8 is a so-called source / drain region
Is the impurity introduction part.

This phototransistor uses a thin film phototransistor which can be formed almost at the same time as the process of manufacturing a thin film transistor (TFT). This thin film phototransistor serves as a photoelectric conversion element (solid-state image pickup element) of the image sensor. Figure 2
Then, the input light is input from the upper surface and photoelectrically converted in the active layer 3.

FIG. 3 is an explanatory view (1) of the solid-state image sensor forming process, and FIG. 4 is an explanatory view (2) of the solid-state image sensor forming process.
Is. Hereinafter, description will be given based on FIGS. 3 and 4. Board 1
For example, an inexpensive low-grade single crystal silicon substrate or a polycrystalline silicon substrate is used, and 300 n is obtained by thermal oxidation.
m thermal oxide silicon film is formed. The silicon oxide film thus formed may contain impurities depending on the grade of the silicon substrate 1 used. Therefore, a clean silicon oxide film of 200 nm is further formed by the low pressure vapor deposition (LPCVD) method to form the insulating film 2. Formed (see FIG. 3A).

After that, as the active layer 3, 200 nm thick amorphous silicon is formed by plasma CVD. The film forming conditions at this time were silane used as a reaction gas, a reaction temperature of 200 ° C., a gas pressure of 5.3 Pa,
By performing RF (high frequency) power of 35 W at a deposition rate of 6 nm / min, and further heating at 600 ° C. for 20 hours, amorphous silicon grows in a solid phase and becomes crystalline (FIG. 3).
(B)). An LPCVD method may be used instead of the plasma CVD method.

Polycrystalline silicon active layer 3 thus obtained
Is patterned into an island shape (see FIG. 3C). Subsequently, the polycrystalline silicon active layer 3 is thermally oxidized so that the gate silicon oxide film 4 becomes, for example, 100 nm (FIG. 3).
(D)).

Immediately after the formation of the silicon oxide film 4, L
Phosphorus (P) is used as the gate electrode 5 by the PCVD method.
N doped with about 10 ²⁰ atoms / cm ³ or more
⁺ Polysilicon (poly-Si) is deposited to a thickness of about 200 nm (see FIG. 3E).

Next, the gate electrode 5 is patterned by the dry etching method, and then the silicon oxide film 4 on the active layer 3 forming the contact layer is partially or completely removed (see FIG. 3 (f)).

Impurities are introduced by ion implantation or ion doping to form an impurity introduction part 8. N
Phosphorus (P) is applied to the mold at an acceleration voltage of 60 KV 1 × 1
Implanting 0 ¹⁵ atoms / cm ² (see FIG. 4A).
Further, for the P type, a portion where the introduction of impurities is not desired is covered with a photoresist 9 and boron (B) is added to 40K.
After implanting a dose of 5 × 10 ¹⁵ atoms / cm ² with an accelerating voltage of V (see FIG. 4B), 600 ° C. in a nitrogen atmosphere to activate the introduced impurities.
Heat treatment is performed for 12 hours at the annealing temperature.

Next, a silicon oxide film or PSG (Phospho) is used as the interlayer insulating film 6 by the atmospheric pressure CVD method.
After forming a Silicate Glass film with a thickness of about 800 nm (see FIG. 4C), a contact hole is opened (see FIG. 4D), and aluminum (Al) 7 is formed with a sputtering method (see FIG. 4). (See (e)). After that, patterning is performed to provide Al wiring (see FIG. 4F). Finally, in order to improve electric characteristics, annealing treatment is performed in a hydrogen atmosphere at 350 ° C. for 1 hour. As a result, a desired image sensor, that is, the solid-state image sensor 10 and the reading drive circuit 2
0 can be obtained at the same time.

FIG. 5 is an explanatory view of a process of forming a thin film light emitting device. In FIG. 5, first, a substrate made of glass or the like having substantially the same thickness as the substrate 1 of the solid-state imaging device 10 which is the transparent substrate 21 is washed (see FIG. 5A).

Next, the transparent electrode 22 is formed on the transparent substrate 21.
A film of ITO (Indium Tin Oxide) is formed (see FIG. 5).
(See (b)), and patterning this ITO film (see FIG. 5).
(See (c)), and the insulating film 23 is formed thereon. The insulating film 23 is SiO ₂ is a main component for example SOG (Sp
An in-on glass) film is formed (see FIG. 5D). At this time, hydrogenation treatment is performed as necessary to improve the characteristics of ITO (reduce resistance and improve light transparency).

Next, the insulating film 23 is patterned (see FIG. 5E), and the organic EL film 24 is mask-deposited by resistance heating (see FIG. 5F). This organic EL film 24
5F is composed of, for example, three layers of an electron transport layer 24-1, a hole transport layer 24-2, and a light emitting layer 24-3.

Further, a MgAg (magnesium-silver alloy) film 25 is vapor-deposited (see FIG. 5 (g)), and then the wiring electrode 2 is formed.
As 6 is formed a film of Al by vapor deposition or sputtering (see FIG. 5 (h)).

The Al film is patterned to form the wiring electrode 26.
Then, the thin film light emitting device 30 is formed (see FIG. 5I). Next, as shown in FIG. 1, the side surface of the transparent substrate 21 of the thin film light emitting device 30 is covered with a light reflector 29 such as a thin film, a thick film or a metal foil that reflects light such as Al. Then, the transparent substrate 21 and the substrate 1 on which the solid-state imaging device 10 is formed are fixed to a housing (not shown), so that the transparent substrate 21 is fixed adjacent to the side surface of the substrate 1.

The transparent substrate 21 and the substrate 1 can be fixed in close contact with each other. Further, the light reflector 29 may be provided only on the other side surface when one side surface is in contact with the light reflecting surface.

Further, the solid-state image pickup device 10 and the transparent substrate 2
A transparent thin plate 32 is fixed onto the surface 1 by a transparent adhesive 27 or the like.
As the transparent thin plate 32, a thin glass plate having a thickness of 50 to 200 μm is used. The thickness of this thin glass is 200 μm
In the above case, the adjacent reflected light is mixed in the solid-state image sensor 10, the resolution of the image sensor is deteriorated, and if it is thinner than 50 μm, the strength as a thin plate cannot be maintained.

In this way, it is possible to obtain an image sensor with a light source that is thin, ultra-compact and inexpensive. In addition,
By using a transparent substrate as the substrate 1 of the solid-state imaging device 10, the transparent substrate 21 of the thin-film light emitting device 30 can be the same substrate as the substrate 1, and the cost can be reduced.
Further, the housing for fixing the substrate 1 and the transparent substrate 21 can be an inexpensive flat iron plate or the like.

[Explanatory drawing of the second embodiment] FIG. 6 is an explanatory view of the second embodiment, showing the configuration of an image sensor with a light source. In FIG. 6, the light shielding layer 3 is formed on the substrate 1 such as transparent glass.
1, and a slit-shaped window 33 is formed in the light shielding layer 31. Further, a plurality of solid-state image pickup devices 10, a read drive circuit (not shown), and the like are formed on the light shielding layer 31.

Further, the thin film light emitting element 30 is formed on the transparent substrate 21, and the side surface of the transparent substrate 21 is covered with a light reflector 29 such as a thin film, a thick film or a metal foil which reflects light.
Next, the light irradiation surface of the transparent substrate 21 on which the thin film light emitting element 30 is not formed is brought into close contact with the lower surface of the substrate 1 in which the window 33 is opened. Further, a transparent thin plate 32, which is a thin glass plate, is fixed on the solid-state image sensor 10 and the window 33 with a transparent adhesive 27 or the like.

The solid-state image pickup device 10 and the like and the thin film light emitting device 30 formed on the light shielding layer 31 can be formed of thin films as in the first embodiment. In the second embodiment, the light from the line-shaped thin film light emitting element 30 passes through the transparent substrate 21, the substrate 1, the window 33, and the transparent thin plate 32, and is the original 28.
Is irradiated. The light reflected from the original 28 is transmitted through the transparent thin plate 32.
Is input to the solid-state image sensor 10.

As a result, it is possible to obtain a signal from the solid-state image pickup device 10 according to the shading of the original document 28. In the second embodiment, the substrate 1 of the solid-state image pickup device 10 and the transparent substrate 21 of the thin film light emitting device do not necessarily have to be the same, but the use of the same makes the cost low. Also,
Although the thickness is about twice that of the first embodiment,
If the substrate 1 and the transparent substrate 21 having a thickness of 0.7 to 1.1 mm are used, the size is about 1.4 to 2.2 mm even when they are overlapped, which is smaller than the conventional LED house 42.

Further, since the spot light can be applied to the original through the window opened in the light shielding layer 31 in contact with each solid-state image pickup device 10, the resolution of the image sensor can be improved. Further, in the above description, the organic EL film has a three-layer structure of an electron transport layer, a hole transport layer, and a light emitting layer.
The present invention is of course not limited to this, and for example,
A two-layer structure such as an electron transport layer (light emitting layer) and a hole transport layer, or an electron transport layer and a hole transport layer (a light emitting layer) may be used.

In the above description, the manuscript is not limited to documents and figures written on paper and the like, but also light from a light emitting element such as an object other than paper is reflected and converted into an electric signal. The converted objects are collectively referred to.

[0045]

As described above, the present invention has the following effects. (1) According to the invention described in claim 1, since the side surface of the transparent substrate 21 on which the thin film light emitting element 30 is formed is covered with the light reflector 29 that reflects light, the surface of the read original can be efficiently irradiated. it can. Further, the organic EL film of the thin-film light emitting element 30 is a surface light source unlike a point light source such as a light emitting diode, so that the surface of the read document can be uniformly illuminated without using a light diffusion plate or a lens.

(2) According to the invention described in claim 2, the transparent substrate 21 on which the thin film light emitting device 30 is formed is adjacent to the substrate 1 on which the solid-state image pickup device 10 is formed, and the flat plate surface of the housing is formed. It can be made thin and inexpensive by fixing it to the like.

(3) According to the invention described in claim 3, since the original is irradiated through the window 33 opened in the light shielding layer 31 in contact with the solid-state image sensor 10, the resolution of the image sensor can be improved. it can.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a phototransistor according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram (1) of a forming process of the solid-state image sensor according to the first embodiment of the present invention.

FIG. 4 is an explanatory view (2) of the forming process of the solid-state image sensor according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of the forming process of the thin film light emitting device according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 substrate 10 solid-state image sensor 20 reading drive circuit 21 transparent substrate 27 transparent adhesive 28 original document 29 light reflector 30 thin film light emitting element

Claims (3)

[Claims] 1. A transparent substrate (21) comprising a solid-state imaging device for inputting reflected light of a document and a thin film light emitting device for illuminating the document, wherein the thin film light emitting device has at least one side surface covered with a light reflector. ) An image sensor with a light source characterized by being formed on the above. 2. A substrate (1) on which a solid-state image sensor is formed.
And a transparent substrate (21) on which a thin film light emitting device having substantially the same thickness as the substrate (1) is formed, the transparent substrate (21) is adjacent to the side surface of the substrate (1), and both are substantially in the same plane. The image sensor with a light source according to claim 1, wherein the image sensor is fixed so that 3. A solid-state imaging device is formed on a transparent substrate (1) via a light-shielding layer, a window is provided in the light-shielding layer of the substrate (1), and a bottom surface of the substrate (1) provided with the window is provided. Transparent substrate (21)
The image sensor with a light source according to claim 1, wherein the irradiation surfaces of the image sensor are closely contacted with each other.