JP2889621B2 - Image input device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image input device using an optical waveguide,
More specifically, using a plurality of optical waveguides formed in parallel with a minute gap therebetween, optically coupled to these optical waveguides, and for each photoelectric conversion element formed integrally, The present invention relates to an image input device configured to guide reading light from an image on a surface to be read, that is, an improved structure of a so-called image reading element.

[Conventional technology]

FIGS. 6 to 8 schematically show a schematic configuration of an image reading element using this type of optical waveguide according to each conventional example.

That is, FIGS. 6A and 6B are a plan configuration diagram and a cross-sectional configuration diagram showing a basic outline of a conventional image reading element. In each of the drawings, the image reading element is provided on a substrate 1 made of glass, metal, plastics, ceramics, or the like, and a plurality of optical waveguide layers 2 made of glass, plastics, or the like are mutually spaced at a predetermined pitch. P is formed in parallel with a small gap therebetween, and a common transparent lower electrode layer 4 extending between the optical waveguide layers 2 and an individual And an upper electrode layer 5 formed on each photoelectric conversion layer 3.
And

FIGS. 7 (a) and (b) of FIGS. 7 and 8 are a plan view and a sectional view, respectively, showing an outline of another conventional image reading element. In the configuration of FIGS. 7 (a) and 7 (b), in the configuration of FIG. 6, the photoelectric conversion layers 3 are insulated from each other by the interlayer insulating layer 6 and individually separated from the photoelectric conversion layers 3. The upper electrode layer 5 is drawn out, and in the configuration of FIGS. 8A and 8B, similarly, in the configuration of FIG.
The lower electrode layer 4 corresponding to the above is insulated and separated by an interlayer insulating layer 6 and the upper electrode layer 5 is made common. The planar shape of each of the electrode layers 4 is completely different from the planar shape of each of the optical waveguide layers 2.

[Problems to be solved by the invention]

When manufacturing the above-described conventional image reading elements, the photoelectric conversion layer 3 and the upper and lower electrode layers 4 are placed on the optical waveguide film uniformly formed on the substrate 1. After forming each of the photoelectric conversion elements consisting of, and 5, an etching mask in the shape of an optical waveguide is formed at a predetermined position on the optical waveguide film by photolithography, and unnecessary portions of the optical waveguide film are selectively formed. Either use means for forming each desired optical waveguide layer 2 having a desired shape by etching away, or select an unnecessary portion of the optical waveguide film uniformly formed on the substrate 1 in the same manner as described above. After optically removing by etching or selectively and partially depositing an optical waveguide material on the substrate 1 to form each optical waveguide layer 2 having a desired shape, each optical waveguide Compatible with layer 2 To the predetermined position, it is common practice to use a means constituting the newly photoelectric conversion element.

As shown in FIG. 9, the image reading element configured as described above has a surface to be read,
For example, reading light 12 from an image obtained by irradiating the original surface 11 with an appropriate light source is guided to each optical waveguide layer 2, and this optical signal is converted by the photoelectric conversion layer 3 corresponding to each optical waveguide layer 2. When the incident light 12 leaks between adjacent photoelectric conversion layers 3 at this time, the crosstalk increases, and the electric signal is converted to an electric signal. When the degree of optical coupling with the photoelectric conversion layer 3 is small, problems such as a decrease in signal output occur. That is, in conclusion, in the image reading device having the conventional configuration, since the optical waveguide layer 2 and the photoelectric conversion layer 3 are formed by different processes, the optical waveguide layer 2 and the photoelectric conversion layer 3 are formed by different processes. It is extremely difficult to exactly match the position with the photoelectric conversion element part, and based on the displacement between these two parts, the incident light 12 incident on the photoelectric conversion layer 3 part through the optical waveguide layer 2 part This causes the crosstalk to deteriorate and the incident efficiency to decrease.

That is, if this state is described in more detail,
First, as shown in FIG. 10, each of the optical waveguide layers 2 arranged in parallel at a predetermined pitch P is formed.
With respect to each individual photoelectric conversion layer 3 corresponding to each
Is shifted by the distance d in the column direction, the incident light to the corresponding photoelectric conversion layer 3 through the individual optical waveguide layers 2
As the incident light amount decreases, light interference due to an increase in the incident light amount from the adjacent photoelectric conversion layer 3 side increases, and as a result, crosstalk of the image reading element itself deteriorates.

Next, when the arrangement of the photoelectric conversion layer 3 with respect to the optical waveguide layer 2 as shown in FIG. 11A is the interval g as the originally optimum set value, FIG. like,
With respect to the optical waveguide layer 2, the arrangement position of the photoelectric conversion layer 3 is approached in the direction orthogonal to the column, causing a shift of the interval -g. Because it will be lost in the wrapped part,
Usually, in order to avoid such inconveniences, it is necessary to make the above-mentioned set interval g large enough to be several times (about 10 μm at present) the accuracy of the alignment apparatus before manufacturing. There is a disadvantage that the photoelectric conversion layer 3 cannot be arranged at an optimum position with respect to the optical waveguide layer 2, and when the arrangement positions are separated from each other and shifted by an interval + g as shown in FIG. As the distance between the photoelectric conversion layer 3 and the layer 2 increases, the degree of coupling deteriorates, which leads to a decrease in output and an increase in crosstalk.

Therefore, in order to solve such a problem due to the displacement when each of the optical waveguide layers 2 has the predetermined pitch P as described above, the value of the displacement is P / P.
Although it is necessary to reduce the size to about 20 in practice, in photolithography in which the effective width of the element itself is about 200 mm, as in this image reading element, misalignment due to one time alignment is arranged. It is extremely difficult to reduce the thickness of all combinations of the optical waveguide layer 2 and the photoelectric conversion layer 3 to about 2 μm or less. In the case of a high-resolution image reading element, P becomes about 20 μm. The disadvantage of a large misalignment was unavoidable.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image reading device of this type, which eliminates the displacement of each photoelectric conversion layer with respect to each optical waveguide layer in view of such a conventional problem. It is to provide a device.

[Means for solving the problem]

In order to solve the above problem, the image input device according to the present invention is configured such that each of the optical waveguides is arranged in at least a part of a planar shape including at least a portion where each photoelectric conversion layer is arranged in each optical waveguide layer arranged in parallel. Each of the photoelectric conversion layers corresponding to the layers, and finally, the planar shape of the electrode layer provided in each of the photoelectric conversion layers is formed to be the same.

That is, according to the present invention, a plurality of optical waveguide layers formed in parallel with a minute gap for guiding reading light from an image on a surface to be read are optically coupled to each of the optical waveguide layers. In an image input device provided with at least a plurality of photoelectric conversion layers each having an electrode layer, each of the photoelectric conversion layers is disposed on a corresponding optical waveguide layer and provided on the photoelectric conversion layer. The planar shape of one of the electrode layers is formed so as to correspond to the planar shape of at least a portion including the arrangement portion of the photoelectric conversion layer in the corresponding optical waveguide layer, and the optical waveguide layer is formed using the electrode layer as an etching mask. An image input device characterized by being formed by patterning.

[Action]

Therefore, in the image input device of the present invention, the planar shape of at least a portion including the arrangement portion of each photoelectric conversion layer in each optical waveguide layer arranged in parallel corresponds to each of these optical waveguide layers. In each of the photoelectric conversion layers, the planar shape of one of the electrode layers provided in each of the photoelectric conversion layers is formed to be the same, and the optical waveguide layer is patterned and formed using the electrode layer as an etching mask. At the time of manufacturing, the displacement of each photoelectric conversion layer with respect to each optical waveguide layer can be effectively eliminated.

〔Example〕

Hereinafter, other embodiments of the image input apparatus according to the present invention will be described in detail with reference to FIGS. 1 to 5.

FIGS. 1 (a) and 1 (b) are a plan view and a sectional view schematically showing an outline of an image reading element to which a first embodiment as a typical example of the present invention is applied. FIGS. 7A and 7B are plan view patterns respectively showing the lower lower electrode layer and the lower upper electrode layer in the first embodiment. In FIG. 1 and FIG.
In the configuration of the first embodiment shown in the figure, the same reference numerals as those of the conventional example shown in FIGS. 6, 7 and 8 denote the same or corresponding parts.

Also in the configuration of the first embodiment shown in each of FIGS. 1 and 2, the image reading element is mounted on the substrate 1 made of glass, metal, plastics, ceramics, or the like, and the glass or plastics is used. A plurality of optical waveguide layers 2 are formed in parallel with each other with a small gap at a predetermined pitch P, and formed on each of the optical waveguide layers 2. The lower lower electrode layer 4a (FIG. 2 (a)) serving as a common electrode layer to be formed, and the optical waveguide layers 2 on the lower lower electrode layer 4a are laminated and formed at corresponding positions. A transparent lower upper electrode layer 4b (FIG. 2 (b)), a photoelectric conversion layer 3 formed on each of these respective lower upper electrode layers 4b, and optically coupled thereto; Upper electrode layer formed on each photoelectric conversion layer 3 And a respective photoelectric conversion portion comprising a.

The image reading device according to the first embodiment is manufactured sequentially through the following steps.

That is, first, on a substrate 1 made of glass, metal, plastics, ceramics, etc., glass, SiO
Single-layer or multi-layer optical waveguide films made of inorganic materials such as ₂ , Si ₃ N ₄ , SiON, or resins such as PMMA, polyimide, etc., are subjected to plasma CVD, sputtering, vacuum evaporation,
It is deposited by a film forming technique such as a coating method.

Then, on this optical waveguide film, Al, Cr, Au, Cu, A
A lower lower electrode layer 4a made of a metal film such as g, W, Ti, Ta, Mo, or a laminated film of some of them, and a lower upper electrode layer 4b made of a transparent conductive material are sequentially formed. And a photoelectric conversion layer 3 on the lower upper electrode layer 4b and an upper electrode layer 5 on the photoelectric conversion layer 3, respectively.
Unnecessary portions of the optical waveguide film are selectively removed by dry etching to form an intended optical waveguide layer 2, and thus an intended image reading element, that is, an image input device can be configured. You can.

Here, in the dry etching, the material of the optical waveguide film, the material of the lower lower electrode film 4a, and the material of the lower lower electrode layer 4a are so set that the metal film of the lower lower electrode layer 4a serves as an etching mask for the optical waveguide film. The composition of the etching gas is selected for each. That is, for example, when the optical waveguide film is made of SiO ₂ and Si ₃ N ₄ or an intermediate composition thereof, and the lower lower electrode film 4a is made of Al and CHF ₃ is used as an etching gas, this CHF in the dry etching using ₃ gas, whereas the SiO _2, and Si ₃ N ₄ or their intermediate composition, is removed with a large etching rate of 500 to 2000 / min, Al is 50 or less ～200A / min
And the photoconductive film side can be removed with a relatively good selectivity by selecting the etching conditions in this manner. At this time, if necessary, the photoelectric conversion equivalent It is also possible to appropriately protect the portion with masking or a shutter plate.

In the first embodiment, the planar shape of the lower lower electrode layer 4a in the portion corresponding to the photoelectric conversion is the same as the planar shape of the optical waveguide layer 2, but the upper electrode layer in the portion corresponding to the photoelectric conversion is used. Even when the planar shape of the optical waveguide layer 2 is the same as the planar shape of the optical waveguide layer 2, the dry etching process of the optical waveguide layer 2 is shifted after the formation of the upper electrode layer 5, so that the image reading of the same configuration is performed. An element can be obtained.

Thus, in the case of the image reading element of the first embodiment configured as described above, the opening provided corresponding to each optical waveguide layer 2 acts as a window for the incident light 12 to the photoelectric conversion element, The accuracy of the relative position between the position of the optical waveguide layer 2 and the position of the opening in the pattern of the lower lower electrode layer 4a is 0.1 μm.
m or less can be easily achieved by the current technology. Therefore, in the image reading element having the electrode layer having the shape including the shape of the optical waveguide layer in the first embodiment,
There is no fear that problems such as a decrease in the incident efficiency and a deterioration in the crosstalk due to the displacement as in the above-described conventional example will occur.

On the other hand, regarding the manufacturing process, in the case of the configuration of the conventional example, the photoelectric conversion layer 3 is made larger or the upper electrode is made larger in order to absorb the displacement generated when the upper electrode layer 5 is laminated on the photoelectric conversion layer 3. If the layer 5 is made small, that is, if the photoelectric conversion layer 3 is made large in this case, the crosstalk is increased. Therefore, it is necessary to make the upper electrode layer 5 small. Although the area reduction of 3 caused the S / N ratio of the output signal to drop,
In the case of the configuration of the first embodiment, the reading light 12 enters from the opening precisely corresponding to the position of the optical waveguide layer 2, and the sizes of the photoelectric conversion layer 3 and the upper electrode layer 5 are compared. The crosstalk does not worsen even if it is set freely, so that the area of each part can be set appropriately large, so that the crosstalk can be effectively suppressed and a good output signal can be obtained.
This has the advantage that the S / N ratio can be improved at the same time.

Here, the means for manufacturing the image reading element according to the first embodiment will be described more specifically.

Pyrex glass as the substrate 1, SiON film as the optical waveguide layer 2, Al as the lower lower electrode layer 4a, lower upper electrode layer 4
The image reading device according to the first embodiment was manufactured by the following procedure using ITO as b, amorphous Si as the photoelectric conversion layer 3, and Al as the upper electrode layer 5, respectively.

That is, first, after the substrate 1 was cut into a predetermined size and washed, an SiON film was deposited to a thickness of 10 μm on the entire surface of the substrate 1 by a plasma CVD method. At this time, a mixed gas of SiH ₄ gas and N ₂ O gas was used as a raw material gas, and their flow rates were set to 20 cc / min and 100 cc / min, respectively.
The film was formed under the conditions of a substrate temperature of 350 ° C., a pressure of 0.1 Torr, and an RF power density for plasma generation of 0.3 W / cm ² .

Subsequently, over the entire surface of the SiON film on the substrate 1, Al serving as the lower lower electrode layer 4a is deposited to a thickness of 1 μm by a vacuum evaporation method, and this is shown in FIG. 2 (a). It is selectively etched to have a planar shape. At this time, wet etching using an aqueous HCl solution was used as an etching means. In addition, an ITO film to be the lower upper electrode layer 4b is formed on the entire surface of the Al layer by a sputtering method, and is selectively formed so as to have a planar shape shown in FIG. Was formed by patterning.

Next, amorphous Si to be the photoelectric conversion layer 3 was deposited on these entire surfaces by a plasma CVD method. At this time, a mixed gas of SiH ₄ gas and H ₂ gas was used as the raw material gas, and the flow rates thereof were 10 cc / min and 100 cc / min, respectively.
The film was formed under the conditions of a substrate temperature of 300 ° C. and an RF power density of 0.1 W / cm ² . Thereafter, Al serving as the upper electrode layer 5 was deposited by a vacuum evaporation method, and these were selectively patterned and formed into an intended shape.

Further, the SiON film, that is, the Si that becomes the optical waveguide
The ON film is formed by patterning using the etching mask for the lower lower electrode layer 4a. This etching includes electron cyclotron resonance reactive etching,
According to the so-called ECRRIBE method, a mixed gas of CHF ₃ gas and O ₂ gas is used as a source gas, and the flow rate of each gas is set at 50%.
cc / min and 2 cc / min, a pressure of 1 × 10 ⁻⁴ Torr, a microwave power of 800 W, and an ion acceleration energy of 200 V. At this time, the photoelectric conversion element portion was etched by etching. This was done by covering this with a polyimide resin so as not to be performed. That is, by dry etching of the SiON film, the optical waveguide layer 2 is patterned and formed into the same shape as the lower lower electrode layer 4a of Al, and in this way, FIGS. 1 (a) and 1 (b). As a result, the expected image reading device was obtained.

The results of comparison between the characteristics of the image reading device according to the first embodiment having the above-described configuration and the characteristics of the image reading device having the conventional configuration are shown in Table 1 below.

As is clear from the above table, in the image reading device according to the configuration of the first embodiment, in manufacturing,
Effective crosstalk suppression performance and good and sufficient light output can be achieved at the same time without applying special film formation methods or using equipment with sufficiently high alignment accuracy. You can do it.

FIG. 3 is a schematic plan view showing an image reading element according to a second embodiment of the present invention.

In the configuration of the second embodiment, grooves 7 for optical path separation are respectively formed between the above-described photoelectric conversion element portions, particularly, at positions corresponding to both sides of each photoelectric conversion element portion. With the formation of the respective optical path separating grooves 7, 7, the occurrence of the crosstalk can be further reduced.

Here, the formation of each of the grooves 7 for separating the optical path is, on the other hand, in the case of the above-described conventional example configuration, in order to absorb the positional shift indicated by the symbol d in FIG. This means that the area of each photoelectric conversion element must be slightly reduced. In the case of the configuration of the second embodiment,
By applying the means described in the configuration of the first embodiment, the displacement amount d can be made extremely small, and as a result, the area of each photoelectric conversion element can be effectively utilized.

4 (a) and 4 (b) are plan views schematically showing an image reading element according to a third embodiment of the present invention.
FIG.

In the configuration of the third embodiment, the planar shape of each of the above-described upper electrode layers 5 is made to include the planar shape of each of the corresponding optical waveguide layers 2. The configuration of the third embodiment is almost the same as the configuration of the first embodiment, except that the patterning of each optical waveguide layer 2 is performed after the patterning of each upper electrode layer 5.

According to the configuration of the third embodiment,
With respect to the set width of the optical waveguide layer (this set width is determined by the resolution of the image reading element to be obtained), each photoelectric conversion element portion having a size that maximizes the width is used. It can be formed on each optical waveguide portion without displacement. Here, in the case of the above-described conventional example configuration, no matter how high the accuracy of the apparatus and the method means used to obtain the same configuration as the third embodiment, the required accuracy itself is sub- In consideration of the micron class and the fact that the effective width in the parallel direction of each optical waveguide portion of the device itself is about 200 to 300 mm, it was practically impossible to form. However, in the case of the third embodiment, as described above, since there is no possibility that the position shift occurs in principle, the same operation and effect as those of the previous example can be obtained, which is very useful.

FIGS. 5 (a) and 5 (b) are a plan view and a sectional view schematically showing an image reading element according to a fourth embodiment of the present invention.

In the configuration of the fourth embodiment, the planar shape of each of the lower lower electrode layers 4a is the same as the planar shape on the photoelectric conversion element portion side in each corresponding optical waveguide layer 2. In the manufacture, a thin conductive material layer 8 is formed between the substrate 1 and each of the optical waveguide layers 2, and then the respective lower portions formed in the case of the first embodiment are formed. A corresponding part of the lower electrode layer 4a can be formed by selectively removing the same by wet etching in the same manner.

According to the configuration of the fourth embodiment,
In addition to the advantage that the displacement does not occur as described in each of the embodiments, the capacitance between the conductive material layer 8 and each lower lower electrode layer 4a can be adjusted to a desired value. When reading the light output from this device externally, it is possible to obtain the configuration of an image reading element to which an optimum capacitance is added in terms of circuit design.

〔The invention's effect〕

As described in detail above, according to the present invention, a plurality of optical waveguide layers formed in parallel with minute gaps for guiding reading light from an image of a surface to be read, and each of these optical waveguide layers In an image input device having at least a plurality of photoelectric conversion layers that are optically coupled to each other and each of which has an electrode layer, the arrangement of at least each photoelectric conversion layer in each of the optical waveguide layers arranged in parallel With respect to the planar shape of a part including the part, each photoelectric conversion layer corresponding to each of these optical waveguide layers, in other words, in this case, one plane of the electrode layer provided in each photoelectric conversion layer Since the shape is formed identically and the optical waveguide layer is patterned and formed using the electrode layer as an etching mask,
At the time of manufacturing the device, the displacement of each photoelectric conversion layer with respect to each optical waveguide layer can be effectively eliminated without using a special method or a high-precision alignment device. Effective activity of the area given to the element portion can be achieved, and as a result, good and sufficient optical output can be achieved simultaneously with effective and effective crosstalk suppression performance. It has excellent features such as being relatively simple in structure and being easily and inexpensively provided.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) show a first embodiment of the present invention.
FIG. 2A is a plan view schematically showing the outline of an image reading element to which the embodiment is applied, and FIG.
FIG. 3B is a plan view showing the lower lower electrode layer and the lower upper electrode layer of the first embodiment, respectively, and FIG. 3 is a schematic view of an image reading device according to the second embodiment. FIG. 4 (a), (b)
5 is a plan view schematically showing the outline of the image reading device according to the third embodiment, and FIG. 5A and FIG. 5B are schematic sectional views showing the outline of the image reading device according to the fourth embodiment. FIGS. 6 (a) and 6 (b) to 8 (a) and (b) are schematic plan views and cross-sectional views schematically showing different image reading elements according to a conventional example. FIG. 9 is a schematic plan view and a schematic cross-sectional view, respectively. FIG. 9 is a cross-sectional view illustrating an example of an image reading state by the image reading element, and FIGS. 10 and 11 (a) to (c). FIG. 9 is a plan view illustrating another example of a positional shift of the photoelectric conversion element with respect to the optical waveguide in the conventional example. DESCRIPTION OF SYMBOLS 1 ... board | substrate, 2 ... optical waveguide layer, 3 ... photoelectric conversion layer, 4a, 4b ... lower lower side, upper electrode layer, 5 ... upper electrode layer, 7 ... groove | channel part for optical path separation, 8 ... Conductive material layer.

────────────────────────────────────────────────── (5) References JP-A-2-302165 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 27/146 H04N 1/028

Claims (1)

(57) [Claims] 1. A plurality of optical waveguide layers formed in parallel with a minute gap for guiding reading light from an image on a surface to be read, and optically coupled to each of the optical waveguide layers. And an image input device comprising at least a plurality of respective photoelectric conversion layers each having an electrode layer, wherein each of the photoelectric conversion layers is disposed on a corresponding optical waveguide layer and provided on the photoelectric conversion layer. One planar shape of the electrode layer is formed so as to correspond to a planar shape of at least a part including the arrangement portion of the photoelectric conversion layer in the corresponding optical waveguide layer, and the optical waveguide layer is patterned using the electrode layer as an etching mask. An image input device characterized by being formed.