Method for manufacturing an imaging device

Abstract

To provide an image sensor which can be configured to be compact without needing pixel miniaturization to form a free curved shape and without needing a complicated control method to compensate variations between sensors while needing no advanced alignment of an optical system, and a manufacturing method thereof.SOLUTION: An image sensor includes a plurality of image sensor units 10 stacked on the top face of a thin film substrate 21 and having a light-receiving surface with a non-planar shape, each image sensor unit including: a thin film substrate 21; an organic photoelectric conversion element 22 including a pixel electrode 23, an organic film 24 and a counter electrode 25 which are stacked in this order on a lateral face of the thin film substrate 21 so as to form the light-receiving surface where light from the side of the thin film substrate 21 enters; and a readout circuit 26 for reading out signals from the organic photoelectric conversion element 22, the readout circuit being formed on the top face of the thin film substrate 21.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an image sensor used as various sensors and a method for manufacturing the same. Specifically, the present invention relates to an image sensor that operates by connecting a photoelectric conversion unit provided on a substrate to a readout circuit. Child It relates to a manufacturing method.

Background Art

[0002] The realization of a curved surface sensor having a non-planar shape of a light receiving portion, such as a wide viewing angle sensor using a ball lens or a contact type sensor directly attached to the skin, has been desired. In a conventional sensor using a ball lens, a device in which an optical fiber or an optical waveguide and a planar sensor are combined in a light receiving portion (see Patent Documents 1 and 2 below), or a device in which a plurality of planar sensors are combined in a light receiving portion of a ball lens (see Patent Document 3 below) has been proposed.

[0003] In addition, in a contact type sensor or the like, a method of forming a sensor on a flexible non-planar body by a transfer technique (see Patent Document 4 below) has been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the above-described wide viewing angle sensor or the like, when the light receiving portion is configured by combining a complex optical system such as an optical fiber or an optical waveguide, it is difficult to make the configuration of the sensor compact, and there is a problem that high-precision alignment is also required. Further, when the light receiving portion is configured by combining a plurality of planar sensors, in addition to the need to perform high-precision optical axis alignment, there is a problem that it is necessary to incorporate a complicated control method for correcting variations between the sensors.

[0006] Further, when the sensor is formed on a flexible non-planar body by a transfer technique, there are problems that high-precision alignment is difficult and it is difficult to miniaturize pixels in order to form a free curved surface shape.

[0007] The present invention has been made to solve such problems, and it is unnecessary to perform high-precision alignment of the optical system, it is unnecessary to miniaturize pixels for forming a free curved surface shape, and it is unnecessary to perform a complicated control method for correcting variations between the sensors. It is an object of the present invention to provide an imaging element manufacturing method that can have a compact configuration. Child

Means for Solving the Problems

Means for Solving the Problems

[0008] In order to achieve the above object, the imaging element manufacturing method of the present invention has the following configuration. Child The manufacturing method is configured as follows.

[0014] That is A first method for manufacturing an imaging element according to the present invention includes: preparing a substrate in a desired curved shape, a first step of forming a light receiving portion having a light receiving surface for receiving light incident from the side of the substrate on the side surface of the substrate by laminating a pixel electrode, an organic film, and a counter electrode in this order; a second step of forming a readout circuit for reading out a signal from the organic optoelectronic conversion element on the upper surface of the substrate; and a third step of laminating a plurality of imaging element units created by performing the first step and the second step in the direction in which the upper surface faces. It is characterized by the following.

[0015] Next, the second method for manufacturing an image sensor according to the present invention is as follows. Prepare a substrate with a desired curved shape. In a region on the substrate on the incident side of the light, a light-receiving portion having a light-receiving surface for receiving light incident from the side of the substrate is formed by laminating a pixel electrode, an organic film, and a counter electrode in this order in a direction perpendicular to the direction in which the light is incident to form an organic optoelectronic conversion element in a first step. In a second step, a reading circuit for reading a signal from the organic optoelectronic conversion element, which is electrically connected to the pixel electrode, is formed in a predetermined region on the substrate. It consists of a third step of laminating a plurality of image sensor units created by performing the first step and the second step in the perpendicular direction. It is characterized by the following.

Advantages of the Invention

[0016] The image sensor of the present invention Child According to the manufacturing method, since a transfer technique is not required for forming the light-receiving surface, it is possible to easily miniaturize the pixels and form a free curved surface shape. Also, since a transfer technique for the light-receiving surface is not required, high-precision alignment can be dispensed with.

[0017] In addition, when forming a sensor with a wide viewing angle, etc., it is not necessary to combine a complex optical system such as an optical fiber or an optical waveguide to configure the light-receiving portion. Therefore, the configuration of the sensor can be made compact, and high-precision alignment can also be dispensed with. Furthermore, since it is not required to configure the light-receiving portion by combining a plurality of planar sensors, it is not required to perform high-precision optical axis alignment as in the conventional technology described above, and it is not necessary to adopt a complicated control method for correcting variations between the sensors.

[0018] Also, by laminating a plurality of image sensor units to form a stacked image sensor, it is possible to form a large-area sensor with a desired number of pixels.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 3C

Figure 4A

Figure 4B

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0020] Hereinafter, an image sensor and a method for manufacturing the same according to an embodiment of the present invention will be described with reference to the drawings. <First Embodiment> (Configuration of the Image Sensor) FIG. 1(a) is an external view showing the overall structure of an image sensor (curved stacked image sensor) 10A according to the first embodiment, FIG. 1(b) is a conceptual diagram showing an enlarged partial configuration of this curved stacked image sensor 10A, and FIG. 1(c) is a further enlarged view showing a part of one pixel unit 10 constituting this curved stacked image sensor 10A.

[0021] That is, as shown in FIG. 1(c), the pixel unit 10 includes a thin film substrate 21, and an organic photoelectric conversion element 22 formed by laminating a pixel electrode 23, an organic film 24, and a counter electrode 25 in this order on the side surface of the thin film substrate 21 so as to form a light receiving surface on which light from the side of the thin film substrate 21 is incident, and a readout circuit 26 formed on the upper surface of the thin film substrate 21 for reading out signals from the organic photoelectric conversion element (specifically, the pixel electrode 23). The above-described light receiving surface is configured to form a curved cylindrical surface shape. Note that by forming the thin film substrate 21 itself in the curved shape shown in FIG. 1(a), the light receiving surface of the pixel unit 10 can be formed in a predetermined curved shape.

[0022] The pixel unit 10 can constitute an image sensor (sensor) alone, but usually, as shown in Fig. 1(b), for example, the pixel units 10 for R, G, and B are combined (stacked on the upper surface of the thin film substrate 21) to form a color imaging unit of the pixel unit 10. Furthermore, as shown in Fig. 1(a), a plurality of pixel units 10 (preferably regarded as a color imaging unit) (the number designed as the number of pixels in the axial direction of the cylinder) are stacked in the direction in which the upper surface faces (the depth direction in Fig. 1(a)) to form a laminate 29, thereby constructing a curved stacked image sensor 10A. Although not explicitly shown, input / output electrodes are formed on the side of the thin film substrate 21 opposite to the formation side of the organic optoelectronic conversion element 22.

[0023] Note that the pixel electrode 23, the readout circuit 26, and the input / output electrodes are electrically connected in this order. An external voltage is applied to the input / output electrodes and the counter electrode 25. On the other hand, the charges photoelectrically converted by the organic optoelectronic conversion element 22 are read out by the readout circuit 26 from the pixel electrode 23, amplified as appropriate, and output to the outside from the input / output electrodes. Also, in Fig. 1(c), the size of the pixel electrode (the vertical width of the pixel electrode 23 in Fig. 1(c)) is formed to be equal to the thickness of the thin film substrate 21, but it may be formed smaller than the thin film substrate 21 by patterning.

[0024] As described above, the image sensor (curved stacked image sensor 10A) of this embodiment is a curved surface sensor having a shape in which the light receiving surface is curved in one direction, and an organic optoelectronic conversion element 22 in which a pixel electrode 23, an organic film 24, and a counter electrode 25 are stacked in this order is provided on the light receiving surface (the side surface of the thin film substrate 21).

[0025] In the image sensor of this embodiment, since a transfer technique is not required for the formation of the light receiving surface, miniaturization of pixels is easy, formation of a free curved surface shape is easy, and high-precision alignment of the pixel units 10 is not required. Furthermore, when forming a sensor with a wide viewing angle, etc., there is no need to configure the light-receiving part by combining complex optical systems such as optical fibers and optical waveguides. The configuration of the sensor can be made compact, and high-precision alignment is not required. Moreover, since there is no need to configure the light-receiving part by combining a plurality of planar sensors, there is no need to perform highly accurate optical axis alignment, and there is no need to adopt a complicated control method for correcting variations between the sensors. Therefore, the curved surface sensor has many advantages in easily manufacturing it.

[0026] Also, in the image sensor of the present embodiment, it is preferable that each of the image sensor units 10 constitutes a one-line sensor, and it is possible to configure to perform pixel extraction for each image sensor unit 10. As the thin film substrate 21, a thin plastic or a thin metal such as aluminum foil with an insulating film formed thereon can be used.

[0027] By forming the thin film substrate 21 with a resin material such as plastic, the bonding and position adjustment of the image sensor units 10 can be performed flexibly. That is, when the thin film substrate 21 is formed of a hard material, mutual substrates are likely to be damaged due to contact during bonding and position adjustment, but this can be prevented. Also, when a resin material such as plastic is used as the thin film substrate 21, in addition to the advantage that film thickness control is easy, it is also advantageous for mass production and has a great advantage in terms of manufacturing cost.

[0028] Also, although details will be described later, it is also possible to easily form a wide viewing angle sensor in combination with a ball lens.

[0029] Note that the image sensor of the present embodiment is characterized in that, unlike the image sensor of the second embodiment described later, the organic photoelectric conversion element 22 is laminated and formed on the side surface of the thin film substrate 21. As a result of such a configuration, the size of the pixel can be adjusted by the thickness of the thin film substrate 21.

[0030] Hereinafter, the details of the curved stacked image sensor 10A according to the first embodiment will be further described. As described above, in the curved stacked image sensor 10A according to the present embodiment, the organic film 24 is used as the photoelectric conversion film, and the photoelectric conversion element is formed as the organic photoelectric conversion element 22. In addition, the counter electrode 25 can be a common electrode that conducts with each other in all pixels. When the counter electrode 25 is commonly formed in all pixels, it can be configured by connecting only one end of the counter electrode 25 to an external power source or the like.

[0031] In addition, as the material of the organic photoelectric conversion film, a material having sensitivity to a predetermined wavelength can be applied for each image sensor unit 10, and the image sensor units 10 using different materials can be laminated so as to be adjacent to each other. For example, when an organic film material can be formed by coating, a color image sensor may be formed by using a curved stacked image sensor 10A in which the image sensor units 10 to be laminated are arranged in the order of R, G, B (or in the order of R, B, G, or in the order of R, G, B, G, etc.). Furthermore, a color filter and the photoelectric conversion film of the organic film may be combined. In this case, the color separation of the color filter can be either for each line or for each pixel.

[0032] The readout circuit 26 is a circuit necessary for reading out signals from the organic photoelectric conversion element 22, and includes a driving TFT, a selection TFT, a reset TFT, a load capacitor, etc. used in a conventional CMOS pixel circuit, as well as an amplification circuit, various arithmetic circuits, and a circuit for noise reduction. The semiconductor circuit manufacturing technology used in a conventional CMOS image sensor can be used. In addition, a signal readout circuit 26 can also be configured by combining oxide semiconductor TFTs. As a signal readout method from the organic photoelectric conversion element 22, it may correspond to various digital drives, or a normal method of amplifying and reading out each pixel may be applied.

[0033] In addition, in the curved stacked image sensor 10A according to the present embodiment, since a readout circuit and an arithmetic circuit are incorporated for each pixel, the readout method can be freely set for each image sensor unit 10, such as line sensor readout, single-pixel readout, and multi-pixel readout. Further, the arithmetic circuit and the like may be formed on the thin film substrate 21 using a transfer technique.

[0034] The thickness of the thin film substrate 21 can be freely selected according to the material, and can be freely selected within a range of about several 100 nm to several 100 μm, for example, according to the simplicity of the manufacturing process during lamination, the light utilization efficiency, and further according to the use of the element.

[0035] For example, when applying a resin material capable of coating film formation, it is possible to control the thickness to less than 1 μm by applying it extremely thinly and curing it, but it is also possible to form a thin film substrate with a film thickness of 100 μm or more.

[0036] Here, the modes of the curved surface shape of the curved stacked image sensor in the image sensor according to the present embodiment are shown in FIGS. 2(a) and (b). FIG. 2(a) shows a curved stacked image sensor 10B having an inverted S-shaped curved surface shape, and FIG. 2(b) shows a curved stacked image sensor 10C having a spherical curved surface shape. As shown in FIGS. 2(a) and (b), by changing the curved surface shape of the light receiving surface and the lamination method, curved stacked image sensors of various desired shapes can be formed. Note that the timing of processing the light receiving surface into a curved surface can be a timing that is easy to manufacture. Generally, however, it is preferable to set a desired curved shape when creating the thin film substrate 21 and perform subsequent film formation on this curved thin film substrate 21 because it is easy in manufacturing.

[0037] In FIG. 2(a), an aspect is shown in which a plurality of image sensor units 10 (left figure) created by forming each layer on a thin film substrate 21 processed into an S shape are laminated to form a curved stacked image sensor 10B (right figure). On the other hand, in FIG. 2(b), a plurality of pixel element units 10 created by forming each layer on a thin film substrate 21 processed into a semi-circular peripheral shape are laminated to form a curved laminated type pixel element 10C (left figure), and further, with these pixel element units 10 using the central axis (central axis of a virtual sphere) as a support axis, they are opened in the circumferential direction so as to be spaced apart from each other, and an overall spherical ((1 / 4) spherical state) curved laminated type pixel element 10C (right figure) is formed.

[0038] (Manufacturing method of laminated type pixel element) Next, the manufacturing method of the pixel element according to the present embodiment will be described with reference to FIGS. 3A to 3C. First, a large-sized thin film substrate 21 is prepared, and a plurality of basic circuits (readout circuits and wiring electrodes) are simultaneously formed on the surface of this thin film substrate 21. In addition, an arithmetic circuit or the like is also formed as necessary (FIG. 3A(a)).

[0039] Next, the thin film substrate 21 is cut for each basic circuit (FIG. 3A(b)). When it is difficult to form (pattern) electrodes or the like up to the end of the thin film substrate 21, the end of the thin film substrate 21 is cut and removed so that the end of the pattern of the electrodes or the like is located at the end of the thin film substrate 21. Each thin film substrate 21 obtained by cutting is arranged in parallel so that the light receiving surfaces are located on the same plane (FIG. 3A(c)), and a pixel electrode 23 is formed at the light receiving surface position of each thin film substrate 21 using a vapor deposition method, a sputtering method, a coating method, or the like (patterning is also performed simultaneously) (FIG. 3B(d)).

[0040] Next, an organic film 24 (organic photoelectric conversion film, blocking layer, etc.) is formed on the pixel electrode 23 of each thin film substrate 21 using an arbitrary film forming method such as a vapor deposition method or a coating method (FIG. 3B(e)). As shown in the figure, when coating the three RGB photoelectric conversion film materials separately, an organic film 24 (organic film (B) 24B, organic film (G) 24G, organic film (R) 24R) is formed for each color.

[0041] An adhesive layer 28 is applied to the surface side of each thin film substrate 21 (Fig. 3C(f)), and the thin film substrates 21 for each color are bonded together so as to be laminated in a desired order as shown in Fig. 1(b) (Fig. 3C(g)). Thereafter, a curing treatment of the adhesive layer 28 is performed as necessary. Finally, as shown in Fig. 3C(h), a common counter electrode 25 is formed on the organic films 24 (organic film (B) 24B, organic film (G) 24G, organic film (R) 24R) of all the thin film substrates 21 using an arbitrary film forming method such as vapor deposition, sputtering, or coating.

[0042] Regarding the method for manufacturing the image sensor according to the embodiment, it is also possible to use the methods shown in Figs. 4A and 4B instead of the methods shown in Figs. 3A to 3C. That is, in the method of the above-described embodiment, after forming each organic film 24B, 24G, 24R as shown in Fig. 3B(e), as shown in Fig. 3C(g), the thin film substrates 21 are bonded together, and then, as shown in Fig. 3C(h), the counter electrode 25 is formed. However, when using an apparatus capable of film formation according to the curved surface, after bonding the thin film substrates 121 together, it is also possible to use a method of forming the organic film 124 or the like.

[0043] That is, among the series of manufacturing steps shown in Figs. 4A(a) to 4B(f), as shown in Fig. 4A(c), the thin film substrates 121 are bonded together, and then, as shown in Fig. 4B(d), a pixel electrode 123 is formed on the light receiving surface of each thin film substrate 121. Further, as shown in Fig. 4B(e), a step of forming an organic film 124 on the pixel electrode 123 may be used. Note that among the series of manufacturing steps shown in Figs. 4A(a) to 4B(f), the other steps are the same as those of the method of the above-described embodiment shown in Figs. 3A to 3C, and thus the description thereof is omitted. Note that among the members shown in Figs. 4A(a) to 4B(f), the reference numerals of the members corresponding to the members shown in Figs. 3A(a) to 3C(h) are represented by adding 100 to the reference numerals of the members shown in Figs. 3A(a) to 3C(h).

[0044] <Second Embodiment> (Configuration of Image Sensor) FIG. 5(a) is an external view showing the overall structure of the imaging device (curved stacked imaging device) 210A according to the second embodiment, FIG. 5(b) is a conceptual diagram showing an enlarged partial configuration of this curved stacked imaging device 210A, and FIG. 5(c) is a further enlarged view showing one imaging device unit 210 that constitutes this curved stacked imaging device 210A.

[0045] That is, as shown in FIG. 5(c), the imaging device unit 210 includes a thin film substrate 221, and an organic photoelectric conversion element 222 formed by laminating a pixel electrode 223, an organic film 224, and a counter electrode 225 in this order at the light incident side end on the thin film substrate 221 so as to form a light receiving surface for light incident from the side of the thin film substrate 221, and a readout circuit 226 formed on the upper surface of the thin film substrate 221 for reading out signals from the organic photoelectric conversion element 222 (specifically, the pixel electrode 223). The light receiving surfaces of the above-described respective imaging device units 210 are configured to form the same cylindrical surface shape that is curved.

[0046] The imaging device unit 210 can also constitute a curved imaging device (sensor) alone, but usually, for example, imaging device units for R, G, and B are combined in a predetermined order (laminated in a predetermined order in the upper surface direction of the imaging device unit 210) to constitute a color imaging unit of the imaging device unit 210. Furthermore, as shown in FIG. 5(a), a plurality of (the number corresponding to the number of pixels in the axial direction of the cylinder) color imaging units of the imaging device unit 210 are laminated in the upper surface direction thereof to form a laminate 229, thereby constructing the curved stacked imaging device 210A. Note that input / output electrodes 227 are formed on the side of the thin film substrate 221 opposite to the side where the organic photoelectric conversion element 222 is disposed (light incident side).

[0047] Note that the pixel electrode 223, the readout circuit 226, and the input / output electrode 227 are electrically connected in this order, and an external voltage is applied between the pixel electrode 223 and the counter electrode 225 via the input / output electrode 227 and the readout circuit 226. On the other hand, the detection signal (imaging signal) of the organic photoelectric conversion element 222 read out by the readout circuit 226 is output to the outside from the input / output electrode 227.

[0048] As described above, the imaging device 210 of the present embodiment is a curved surface sensor having a shape in which the light receiving surface is curved in one direction, and an organic photoelectric conversion element 222 in which a pixel electrode 223, an organic film 224, and a counter electrode 225 are laminated in this order is provided on the upper surface of the thin film substrate 221.

[0049] In the imaging device of the present embodiment, since a transfer technique is not required for forming the light receiving surface, miniaturization of pixels is easy, formation of a free curved surface shape is easy, and high-precision alignment of the imaging device is not required. Furthermore, even when forming a sensor with a wide viewing angle, etc., it is not necessary to configure the light receiving part by combining a complicated optical system such as an optical fiber or an optical waveguide, the configuration of the sensor can be made compact, and high-precision alignment is not required either. Furthermore, since it is not necessary to configure the light receiving part by combining a plurality of planar sensors, it is not necessary to perform high-precision optical axis alignment, and it is not necessary to adopt a complicated control method for correcting variations between the sensors. Therefore, it has many advantages in terms of easy manufacturing.

[0050] Also, in the curved laminated type imaging device 210A of the present embodiment, it is preferable that each of the imaging device units 210 constitutes a one-line sensor, and it is possible to configure the device to perform pixel extraction for each imaging device unit 210. As the thin film substrate 221, a thin plastic or a thin metal such as aluminum foil with an insulating film formed thereon can be used.

[0051] By forming the thin film substrate 221 from plastic, the bonding and position adjustment of the pixel units 210 can be performed flexibly. That is, when the thin film substrate 221 is formed from a hard material, damage is likely to occur due to the contact of the substrates with each other during bonding and position adjustment, but this can be prevented. Also, when a resin material such as plastic is used as the thin film substrate 221, in addition to the advantage of easy film thickness control, it is also advantageous for mass production and has a great advantage in terms of manufacturing cost.

[0052] Also, although details will be described later, similar to the first embodiment, it is also possible to easily form a wide viewing angle sensor in combination with a ball lens.

[0053] Note that the image sensor of this embodiment is characterized in that, unlike the image sensor of the first embodiment described above, the organic photoelectric conversion element 222 is laminated on the upper surface of the thin film substrate 221 (the surface on which the readout circuit 226 is formed). As a result of such a configuration, the pixel size does not depend on the thickness of the thin film substrate 221. Therefore, compared with the image sensor of the first embodiment described above, the pixels can be made denser, and by making the pixel electrodes larger, incident light can be sufficiently absorbed, so there are advantages such as good light reception efficiency. Furthermore, since the lamination direction in each manufacturing process is all upward on the thin film substrate 21, there is also an advantage that the fabrication of the image sensor is easier compared to the image sensor of the first embodiment. Note that in the pixel unit 210 of the curved laminated type image sensor 210A of this embodiment, the light receiving area of the organic photoelectric conversion element 222 depends on each value of (the length of the side along the thin film substrate 221 at the end face of the pixel electrode 223 on the light receiving surface side) and (the thickness of the organic film 224).

[0054] In addition, in the image sensor of the present embodiment, since it is a so-called side-illuminated image device, it is not necessary to form the counter electrode 225 transparently. Rather, since color mixing between adjacent pixels in the stacking direction (vertical direction) of the pixel electrode 223 and the counter electrode 225 is prevented, it is preferable that these pixel electrodes 223 and counter electrodes 225 be opaque. Therefore, various opaque electrode materials can be applied, and it is also possible to select a material that causes less damage to the organic film 224.

[0055] In addition, in the image sensor of the present embodiment, the pixel electrode 223 can have a large depth direction with respect to the light receiving surface, and since the organic film 224 does not have wavelength dependence in the depth direction, all incident light can be absorbed and utilized without waste, and furthermore, good wavelength characteristics according to the material can be obtained.

[0056] Hereinafter, the details of the image sensor (curved stacked type image sensor) 210A according to the second embodiment will be further described. As described above, in the curved stacked type image sensor 210A according to the present embodiment, the organic film 224 is used as the photoelectric conversion film, and the photoelectric conversion element is formed as the organic photoelectric conversion element 222. In addition, the counter electrode 225 can be a common electrode that conducts with each other in all pixels. When the counter electrode 225 is commonly formed in all pixels, it can be configured by connecting only one end of the counter electrode 225 to an external power source or the like. Note that not only the pixel electrode 223 but also this counter electrode 225 can be connected to the readout circuit 226.

[0057] In addition, as the material of the organic photoelectric conversion film, a material having sensitivity to a predetermined wavelength can be applied for each image sensor unit 210. The image sensor units 210 using different materials in this way can be stacked so as to be adjacent to each other. For example, when an organic film material can be formed by coating, a color image sensor may be formed by using a curved stacked type image sensor 210A in which the image sensor units 210 to be stacked are arranged in the order of R, G, B (or in the order of R, B, G or R, G, B, G, etc.). Furthermore, a color filter may be combined with the photoelectric conversion film of the organic film 224. In this case, the color separation of the color filter can be either for each line or for each pixel. Also, when it is possible to apply and form the organic film 224, it is also possible to perform, for example, RGB coating using different materials within one imaging element unit 210.

[0058] The readout circuit 226 is a circuit necessary for reading the signal from the organic photoelectric conversion element 222, and uses semiconductor circuit fabrication techniques used in conventional CMOS image sensors, such as driving TFTs, selection TFTs, reset TFTs, load capacitors, etc. used in conventional CMOS pixel circuits, as well as amplifier circuits, various arithmetic circuits, and circuits for noise reduction. Also, a signal readout circuit 226 can be configured by combining oxide semiconductor TFTs. As a signal readout method from the organic photoelectric conversion element 222, it may correspond to various digital drives, or a normal method of amplifying and reading out each pixel may be applied.

[0059] Also, in the curved stacked type imaging element 210A according to the present embodiment, since a readout circuit and an arithmetic circuit are incorporated for each pixel, the readout method can be freely set in each imaging element unit 210, such as line sensor readout, single pixel readout, multiple pixel readout, etc. Also, the arithmetic circuit etc. may be formed on the thin film substrate 221 using a transfer technique.

[0060] The thickness of the thin film substrate 221 can be freely selected according to the material, and can be freely selected within a range of about several 100 nm to several 100 μm, for example, depending on the simplicity of the manufacturing process during lamination, the light utilization efficiency, etc., and further depending on the use of the element.

[0061] For example, when applying a resin material capable of coating and film formation, it is possible to control the thickness to less than 1 μm by applying it extremely thinly and curing it, but it is also possible to form a thin film substrate 221 with a film thickness of 100 μm or more.

[0062] Here, conceptual diagrams showing the aspect of the curved surface shape of the curved laminated image sensor in the image sensor according to the present embodiment are shown in FIGS. 2(a) and (b). Since the explanation is the same as that in the case of the first embodiment, repeated explanations for the case of the second embodiment are omitted.

[0063] (Method for manufacturing a laminated image sensor) Next, the method for manufacturing the image sensor according to the present embodiment will be described with reference to FIG. 6. First, a thin film substrate 221 of a predetermined size is prepared (FIG. 6(a)), and a pixel electrode 223, a readout circuit 226, an input / output electrode 227, and further, an arithmetic circuit or the like is formed on the surface of the thin film substrate 221 as necessary (FIG. 6(b)).

[0064] Next, an organic film 224 is formed on the pixel electrode 223 formed on the light incident side of the thin film substrate 221 (FIG. 6(c)). For the formation of the organic film 224, any of dry methods such as vapor deposition method, wet methods such as spin coating method and inkjet method can be used.

[0065] Subsequently, a counter electrode 225 is formed on the organic film 224 (which can be common to all the organic films 224 arranged on the same plane) (FIG. 6(d)). As this formation method, any method such as vapor deposition method, sputtering method, coating method, etc. can be used. At this time, when the input / output electrode 227 cannot be formed up to the end of the thin film substrate 221, a cutting process is performed on the end of the thin film substrate 221, and an auxiliary process is performed so that the input / output electrode 227 is arranged at the end of the thin film substrate 221.

[0066] Finally, an adhesive is applied to a predetermined position on the surface of each thin film substrate 221 to form an adhesive layer 228 (FIG. 6(e)). After that, alignment of the thin film substrates 221 to be laminated is performed, and they are bonded via the adhesive layer 228, and the bonding operation is repeated to form a laminate 229 and complete the curved laminated image sensor 210A (FIG. 6(f)).

[0067] (Additional matters according to the embodiment) Other considerations ((a) to (i)) for each of the above-described embodiments will be described in a list format. (a) Since it is difficult to pattern the electrodes on the light-receiving part by ordinary methods, it is preferable to perform patterning using a shadow mask or the like during the film formation of the electrodes. Instead of the patterning method using a shadow mask, for example, it is also possible to use a method in which a thin wire is used as a mask to form an opening and perform patterning of the electrodes.

[0068] (b) From the viewpoint of improving the manufacturing accuracy, it is preferable to form the organic films 24 and 224 for each pixel element unit 10 and 210 at once for each color (for example, R, G, B). Therefore, it is recommended that all the pixels in one line of the same pixel element units 10 and 210 form the organic films 24 and 224 for the same color. (c) Also, when using a color filter, it is efficient to perform the steps of <1> forming the pixel electrodes 23 and 223, <2> forming the organic films 24 and 224, <3> forming the color filter (preferably forming for each color, and preferably all in the same color for one line as in the case of the organic films 24 and 224), <4> bonding the pixel element units 10 and 210, and <5> forming the counter electrodes 25 and 225.

[0069] (d) Also, in the case of monochrome image imaging etc., when color separation of the organic films 24 and 224 is not required, it is efficient to perform the steps of <1> forming the pixel electrodes 23 and 223, <2> bonding the pixel element units 10 and 210, <3> forming the organic films 24 and 224, and <4> forming the counter electrodes 25 and 225.

[0070] (e) In the process of bonding the above-described imaging element units 10 and 210, as described above, it is effective to form adhesive layers 28 and 228 on the respective thin film substrates 21 and 221, and stack the imaging element units 10 and 210 by overlapping and bonding them to each other. At that time, in order to improve the lamination accuracy, it is necessary to perform the bonding process while aligning the positions of the imaging element units 10 and 210. For this reason, as shown in FIG. 7, it is preferable to use a lamination jig 350 having a curved inner wall surface that conforms to the outer shape of the imaging element unit 310, arrange the imaging element units 310 sequentially along the inner wall surface of the lamination jig 350, and bond them sequentially to produce a curved laminated imaging element 310A.

[0071] (f) The formation of the readout circuits 26 and 226, the input / output electrodes 227, etc. can apply general methods used in semiconductor processes, and there are no particular restrictions on the constituent materials and manufacturing methods. For example, as the electrodes, general conductive materials such as metals and organic conductive films can be applied, and their film formation can be appropriately adopted according to the material, such as sputtering, evaporation, CVD, and various printing methods.

[0072] (g) The patterning of the electrodes can be performed simultaneously with film formation by printing methods or the like in addition to the photolithography method. (h) When crossing various wirings, etc., it is possible to form an insulating film between the wirings as necessary, and their materials and film formation methods can also apply general methods used in semiconductor processes. The same applies to the etching process of the insulating film.

[0073] (i) In the imaging element of this embodiment, as described with reference to FIG. 2(b), a spherical (or a part of a sphere) curved laminated imaging element 10C can be easily formed as a whole. That is, a plurality of image sensor units 10 created by forming each layer on a thin film substrate 21 processed into a semi-circular peripheral shape are stacked to form a curved stacked type image sensor 10C as shown in the left figure of Fig. 2(b). Further, these image sensor units 10 can be opened in the circumferential direction with a central axis (the central axis of a virtual sphere) as a support axis and spaced apart from each other to form a curved stacked type image sensor 10C as shown in the right figure of Fig. 2(b). Furthermore, as shown in Fig. 8, by disposing a ball lens 440 inside the curved stacked type image sensor 410C and holding it by a transparent support 442 so that the ball lens 440 is positioned at the center of the curved stacked type image sensor 410C (furthermore, surrounded by a plurality of image sensor units 410), it is possible to easily form an ultra-wide viewing angle sensor.

[0074] In the image sensor and its manufacturing method of the present invention, it is not limited to the above-described embodiment, and various other modifications are possible. For example, it is also possible to use an image sensor unit to which a photoelectric conversion layer having sensitivity to ultraviolet rays or infrared rays is applied. Also, in the above-described second embodiment, the readout circuit is formed in a region where the organic photoelectric conversion element is not formed. However, in the stacked type image sensor of the present invention, the readout circuit may be formed in a region where the organic photoelectric conversion element is formed, and this readout circuit may be configured to be covered with an organic film or a counter electrode. Also, as the manufacturing method of the stacked type image sensor of the present invention, it is not limited to the order of the steps according to the above-described embodiment. In particular, the manufacturing process of the light receiving part (organic photoelectric conversion element) (the first step) and the manufacturing process of the readout circuit (the second step) may be performed in either order first, or any stage of the first step and any stage of the second step may be performed in either order (even simultaneously).

Explanation of Reference Numerals

[0075] 10, 210, 310, 410 Image sensor unit 10A, 10B, 10C, 210A, 310A, 410C Curved stacked type image sensor 21, 121, 221 Thin film substrate 22, 222 Organic optoelectronic conversion element 23, 123, 223 Pixel electrode 24, 24B, 24G, 24R, 124, 224 Organic film 25, 125, 225 Counter electrode 26, 126, 226 Readout circuit 227 Input / output electrode 28, 128, 228 Adhesive layer 29, 129, 229 Laminate 350 Laminating jig 440 Ball lens 442 Transparent support

Claims

1. Prepare a substrate in a desired curved shape, a first step of forming an organic optoelectronic conversion element by laminating a pixel electrode, an organic film, and a counter electrode in this order on a side surface of the substrate to form a light receiving portion having a light receiving surface for receiving light incident from the side of the substrate; a second step of forming a readout circuit for reading a signal from the organic optoelectronic conversion element on the upper surface of the substrate; a third step of laminating a plurality of the pixel element units created by performing the first step and the second step in the direction in which the upper surface faces; A method for manufacturing an image sensor, characterized by the above.

2. Prepare a substrate in a desired curved shape, a first step of forming an organic optoelectronic conversion element by laminating a pixel electrode, an organic film, and a counter electrode in this order in a direction orthogonal to the direction in which the light is incident on a region on the light incident side of the substrate on the substrate to form a light receiving portion having a light receiving surface for receiving light incident from the side of the substrate; a second step of forming a readout circuit for reading a signal from the organic optoelectronic conversion element, which is electrically connected to the pixel electrode, in a predetermined region on the substrate; a third step of laminating a plurality of the pixel element units created by performing the first step and the second step in the orthogonal direction; A method for manufacturing an image sensor, characterized by the above.

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