Imaging device

Abstract

This imaging device is provided with a first electrode, a photoelectric conversion film, and a second electrode. The photoelectric conversion film is positioned lower than the first electrode. The second electrode is positioned lower than the first electrode. The second electrode is composed of a plurality of layers. The plurality of layers include a first layer including tantalum nitride. An uppermost layer among the plurality of layers includes a metal nitride.

Description

Technical Field

[0001] The present disclosure relates to an imaging device.

Background Art

[0002] A stacked imaging device is known. The stacked imaging device has a stacked structure including a semiconductor substrate and a photoelectric conversion film. An example of the stacked imaging device is described in Patent Document 1. The electrode of the imaging device of Patent Document 1 has a TiN / Ti structure, that is, a structure in which a titanium nitride layer is disposed on a titanium layer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the electrode of Patent Document 1, metal derived from the outside of the electrode can diffuse.

Means for Solving the Problems

[0005] An imaging device according to an aspect of the present disclosure includes a first electrode, a photoelectric conversion film located below the first electrode, and a second electrode located below the first electrode. The second electrode is composed of a plurality of layers. The plurality of layers includes a first layer containing tantalum nitride. The uppermost layer of the plurality of layers contains a metal nitride.

Effects of the Invention

[0006] In the second electrode according to the present disclosure, diffusion of metal derived from the outside of the second electrode can be suppressed. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic plan view showing the configuration of the imaging device. [Figure 2] Figure 2 is a schematic cross-sectional view showing a part of the imaging device. [Figure 3] Figure 3 is a schematic cross-sectional view showing a portion of the pixel area of ​​an imaging device. [Figure 4A] Figure 4A is a schematic cross-sectional view showing the configuration of the second electrode. [Figure 4B] Figure 4B is a schematic cross-sectional view showing the configuration of the second electrode. [Figure 4C] Figure 4C is a schematic cross-sectional view showing the configuration of the second electrode. [Figure 4D] Figure 4D is a schematic cross-sectional view showing the configuration of the second electrode. [Figure 4E] Figure 4E is a schematic cross-sectional view showing the configuration of the second electrode. [Figure 5] Figure 5 is a schematic top view showing the configuration of the second electrode. [Figure 6A] Figure 6A is a schematic process diagram showing part of the manufacturing process of an imaging device. [Figure 6B] Figure 6B is a schematic process diagram showing part of the manufacturing process of the imaging device. [Figure 6C] Figure 6C is a schematic process diagram showing part of the manufacturing process of the imaging device. [Figure 6D] Figure 6D is a schematic process diagram showing part of the manufacturing process of the imaging device. [Figure 6E] Figure 6E is a schematic process diagram showing part of the manufacturing process of an imaging device. [Figure 6F] Figure 6F is a schematic process diagram showing part of the manufacturing process of the imaging device. [Figure 7A] Figure 7A is a schematic cross-sectional view showing the abnormal oxidation of copper. [Figure 7B] Figure 7B is a schematic cross-sectional view showing the abnormal oxidation of copper. [Figure 8A] Figure 8A is a schematic cross-sectional view showing the configuration of the second electrode. [Figure 8B] FIG. 8B is a schematic cross-sectional view showing the configuration of the second electrode. [Figure 9] FIG. 9 is a schematic cross-sectional view showing the configuration of the second electrode. [Figure 10A] FIG. 10A is a schematic top view showing the configuration of the second electrode. [Figure 10B] FIG. 10B is a schematic top view showing the configuration of the second electrode. [Figure 11A] FIG. 11A is a schematic process diagram showing a part of the manufacturing process of the imaging device. [Figure 11B] FIG. 11B is a schematic process diagram showing a part of the manufacturing process of the imaging device. [Figure 11C] FIG. 11C is a schematic process diagram showing a part of the manufacturing process of the imaging device. [Figure 11D] FIG. 11D is a schematic process diagram showing a part of the manufacturing process of the imaging device. [Figure 12A] FIG. 12A is a schematic process diagram showing a part of the manufacturing process of the imaging device. [Figure 12B] FIG. 12B is a schematic process diagram showing a part of the manufacturing process of the imaging device. [Figure 12C] FIG. 12C is a schematic process diagram showing a part of the manufacturing process of the imaging device. [Figure 12D] FIG. 12D is a schematic process diagram showing a part of the manufacturing process of the imaging device. [Figure 13A] FIG. 13A is a schematic process diagram showing a part of the manufacturing process of the imaging device. [Figure 13B] FIG. 13B is a schematic process diagram showing a part of the manufacturing process of the imaging device. [Figure 13C] FIG. 13C is a schematic process diagram showing a part of the manufacturing process of the imaging device. [Figure 13D] FIG. 13D is a schematic process diagram showing a part of the manufacturing process of the imaging device. [Figure 13E] FIG. 13E is a schematic process diagram showing a part of the manufacturing process of the imaging device. [Figure 14] FIG. 14 is a schematic cross-sectional view showing the state of abnormal oxidation of copper. [Figure 15] Figure 15 is a schematic cross-sectional view showing a photoelectric conversion film. [Figure 16] Figure 16 is a schematic diagram of the camera system. [Modes for carrying out the invention]

[0008] (Knowledge that forms the basis of this disclosure) The electrodes of the imaging device described in Patent Document 1 have a TiN / Ti structure. In these electrodes, metals originating from outside the electrode can diffuse. Such diffusion can lead to various disadvantages, for example, during the manufacturing process of the imaging device.

[0009] For example, if the upper surface of an electrode is exposed to oxygen while metal is diffused on its surface during the manufacturing process, the metal may undergo abnormal oxidation, and clumps of metal oxide may form on the upper surface of the electrode. When a photoelectric conversion film is placed on this electrode, metal atoms from the clumps may diffuse into the photoelectric conversion film, potentially degrading the leakage characteristics of the film. Furthermore, when wiring or another electrode is connected to the upper surface of this electrode, the clumps may interfere with these connections.

[0010] (Summary of one aspect of this disclosure) The imaging device relating to the first aspect of this disclosure is First electrode and, A photoelectric conversion film located below the first electrode, The device comprises a second electrode located below the first electrode. The second electrode is composed of multiple layers. The multiple layers include a first layer containing tantalum nitride. The uppermost layer of the multiple layers contains a metal nitride.

[0011] In the second electrode according to the first embodiment, the diffusion of metals originating from outside the second electrode can be suppressed.

[0012] In a second aspect of this disclosure, for example, in the imaging device according to the first aspect, The aforementioned uppermost layer may be a second layer separate from the first layer.

[0013] According to the second embodiment, the advantages derived from metal nitrides are easily enjoyed while suppressing the disadvantages derived from tantalum nitride.

[0014] In a third aspect of this disclosure, for example, in the imaging device according to the second aspect, The aforementioned second layer may contain titanium nitride.

[0015] According to the third embodiment, a second electrode that takes advantage of the properties of titanium nitride can be realized.

[0016] In a fourth aspect of this disclosure, for example, in an imaging device according to the second or third aspect, The first layer may be thinner than the second layer.

[0017] According to the fourth embodiment, the advantages derived from metal nitrides are easily enjoyed while suppressing the disadvantages derived from tantalum nitride.

[0018] In a fifth aspect of this disclosure, for example, in the imaging device according to the first aspect, The uppermost layer may be the first layer.

[0019] In the uppermost layer according to the fifth embodiment, the diffusion of metals originating from outside the second electrode can be suppressed.

[0020] In the sixth aspect of this disclosure, for example, in an imaging device according to any one of the first to fifth aspects, The bottom layer of the aforementioned multiple layers may contain tantalum.

[0021] According to the sixth embodiment, the second electrode is easily joined to a structure containing a material with high bonding properties to tantalum.

[0022] The imaging device relating to the seventh aspect of this disclosure is: First electrode and, A photoelectric conversion film located below the first electrode, The device comprises a second electrode located below the first electrode. The second electrode includes an electrode body and an insulating film. At least a portion of the upper surface of the second electrode is formed by the electrode body. At least a portion of the lower surface of the second electrode is formed by the electrode body.

[0023] In the second electrode according to the seventh embodiment, the diffusion of metals originating from outside the second electrode can be suppressed.

[0024] In the eighth aspect of this disclosure, for example, the imaging device according to the seventh aspect is: In a cross-section perpendicular to the thickness direction of the insulating film, the insulating film may be surrounded by the electrode body.

[0025] In the second electrode according to the eighth embodiment, the diffusion of externally derived metals into the second electrode can be suppressed while suppressing an increase in the resistance value of the second electrode.

[0026] In the ninth aspect of this disclosure, for example, the imaging device according to the seventh or eighth aspect is: The device may further include a plug having a connecting surface connected to the second electrode and containing metal.

[0027] According to the ninth embodiment, the diffusion of metal originating from the plug can be suppressed in the second electrode, while charge can be extracted from the second electrode by the plug.

[0028] In the tenth aspect of this disclosure, for example, in the imaging device according to the ninth aspect, The electrode body may include a first layer disposed between the plug and the insulating film. The insulating film may contain an oxide, The first layer may contain a non-oxide.

[0029] According to the tenth embodiment, the metal in the plug is less likely to react with oxides derived from the insulating film.

[0030] In the eleventh aspect of this disclosure, for example, in the imaging device according to the ninth or tenth aspect, When viewed from above, at least a portion of the insulating film and at least a portion of the connection surface of the plug may overlap.

[0031] According to the eleventh embodiment, the diffusion of metal originating from the plug is easily suppressed in the second electrode.

[0032] In a twelfth aspect of this disclosure, for example, in the imaging device according to the eleventh aspect, When viewed from above, the entire connection surface may overlap with the insulating film.

[0033] According to the twelfth embodiment, the diffusion of metal originating from the plug is easily suppressed in the second electrode.

[0034] In a thirteenth aspect of this disclosure, for example, in an imaging device according to any one of the ninth to twelfth aspects, The plug may contain copper.

[0035] In the second electrode according to the 13th embodiment, the diffusion of copper originating from the plug can be suppressed.

[0036] In a 14th aspect of this disclosure, for example, in an imaging device according to any one of the 7th to 13th aspects, The electrode body may include a second layer that constitutes the entire upper surface of the second electrode.

[0037] According to the 14th embodiment, the second layer can provide the upper surface of the second electrode with desired characteristics.

[0038] In a 15th aspect of this disclosure, for example, in an imaging device according to any one of the 7th to 9th aspects, The electrode body may include a first layer and a second layer. The insulating film may be located between the first layer and the second layer.

[0039] The configuration of the 15th embodiment is a specific example of a configuration that the second electrode may have.

[0040] In the sixteenth aspect of this disclosure, for example, in an imaging device according to any one of the seventh to fifteenth aspects, The thickness of the insulating film may be 10 nm or more.

[0041] According to the 16th embodiment, the above-mentioned diffusion suppression effect is easily ensured.

[0042] In a 17th aspect of this disclosure, for example, in an imaging device according to any one of the 1st to 16th aspects, In a cross-section parallel to the thickness direction of the photoelectric conversion film, the angle formed between the side surface of the photoelectric conversion film and the lower surface of the photoelectric conversion film may be 70° or more and 90° or less. In the cross-section, at least a portion of the second electrode may be located laterally than the side surface.

[0043] The shape of the photoelectric conversion film in the 17th embodiment can be obtained by dry etching using oxygen. Oxygen can oxidize metals. However, the second electrode in the 17th embodiment can suppress the diffusion of metals originating from outside the second electrode. Therefore, even if the upper surface of the second electrode is exposed to oxygen while the lower surface of the second electrode is in contact with a metal-containing structure, abnormal oxidation of the metal can be suppressed.

[0044] The embodiments of this disclosure will be described in detail below with reference to the drawings.

[0045] The embodiments described below are all either comprehensive or specific examples.

[0046] The numerical values, shapes, materials, components, arrangement and connection configurations of components, steps, and the order of steps shown in the following embodiments are examples only and are not intended to limit the scope of this disclosure. The various embodiments described herein can be combined with each other as long as they do not conflict. Furthermore, among the components in the following embodiments, those not described in the independent claim representing the highest-level concept are described as optional components. Also, each figure does not necessarily illustrate each component precisely. In the following description, components having substantially the same function are indicated by a common reference numeral, and redundant descriptions may be omitted or simplified.

[0047] An imaging device according to one aspect of this disclosure has a photoelectric conversion film on the upper layer that performs photoelectric conversion to convert incident light into an electrical signal, and a signal processing circuit section including a silicon-based CMOS circuit that extracts the electrical signal obtained by the photoelectric conversion film to the outside on the lower layer. In this way, in the imaging device according to one aspect of this disclosure, the photoelectric conversion film and the signal processing circuit section are stacked, so they can be designed independently.

[0048] In the following explanation, terms such as "up," "down," and "side" are used solely to specify the relative positions of the components and are not intended to limit the orientation of the imaging device during use. The same applies to the X, Y, and Z directions. In the diagram, the X and Y directions may correspond to the side directions, and the Z direction may correspond to the up and down directions.

[0049] In the following explanation, the main component refers to the component that is present in the largest quantity by mass. In one example, the main component is a component that makes up more than 50% by mass. In a specific example, the main component is a component that makes up more than 80% by mass.

[0050] (First Embodiment) [1-1. Overall configuration of imaging device 1] The overall configuration of the imaging device 1 according to the first embodiment will be explained with reference to Figure 1.

[0051] Figure 1 is a schematic plan view showing the configuration of the imaging device 1 according to the first embodiment. As shown in Figure 1, the imaging device 1 includes a plurality of pixels 100. The plurality of pixels 100 are arranged in a matrix in the XY direction. In the imaging device 1, a pixel region 10 including the plurality of pixels 100 is formed.

[0052] The pixel region 10 includes multiple readout circuits. Specifically, each pixel 100 includes a readout circuit. In Figure 1, the readout circuits are not shown.

[0053] Outer periphery of the pixel area 10, a vertical driver 12, a timing generator 13, a signal processing circuit 14, a horizontal driver 15, an LVDS (Low Voltage Differential Signaling) device 16, a serial conversion unit 17, a counter electrode voltage supply unit 18, and a plurality of pads 19 are provided.

[0054] The vertical driver 12 performs control to read signals from each readout circuit.

[0055] The timing generator 13 generates and supplies timing for driving the imaging device 1. The timing generator 13 also performs readout control such as decimal readout and partial readout.

[0056] Multiple read circuits constitute multiple columns. The signal processing circuit 14 comprises multiple column circuits. Each of the multiple column circuits is associated one-to-one with each of the columns of the read circuits. Each column circuit performs correlated double sampling (CDS) processing and subsequent AD conversion on the signal output from the corresponding column of the read circuit. The resulting digital signal is stored in a memory provided for each column circuit. Figure 1 omits the illustration of the column circuits.

[0057] The horizontal driver 15 controls the signal processing circuit 14 to sequentially read out one line of signals stored in its memory and output them to the LVDS device 16. The LVDS device 16 transmits digital signals according to LVDS technology. The serial conversion unit 17 converts the input parallel digital signals into serial signals and outputs them.

[0058] The serial conversion unit 17 is optional. Alternatively, the signal processing circuit 14 may perform only correlated double sampling and an AD conversion circuit may be provided instead of the LVDS device 16.

[0059] Alternatively, the signal processing circuit 14 may perform only correlated double sampling, and the LVDS device 16 and serial conversion unit 17 may be omitted. In this case, the AD conversion circuit may be provided outside the chip on which the imaging device 1 is installed.

[0060] Alternatively, a signal processing circuit 14, an LVDS device 16, and a serial conversion unit 17 may be placed in each of the regions adjacent to the pixel region 10. In this case, the rows of multiple read circuits in the pixel region 10 can be processed by the two signal processing circuits 14. For example, half of these rows of read circuits (e.g., odd-numbered rows) can be processed by the signal processing circuit 14 in the region adjacent to the pixel region 10. The remaining half of these rows of read circuits (e.g., even-numbered rows) can be processed by the signal processing circuit 14 in the region adjacent to the pixel region 10.

[0061] [1-2. Detailed Configuration of Imaging Device 1] The detailed configuration of the imaging device 1 will be explained using Figures 2 and 3. Figure 2 is a schematic cross-sectional view showing a part of the imaging device 1. Specifically, Figure 2 refers to a part of the cross-section of Figure 1 cut along the line II-II. Note that in Figure 1, some elements such as the connecting electrode 103 in Figure 2 are not shown. Figure 3 is a schematic cross-sectional view showing a part of the pixel area 10 in the imaging device 1.

[0062] As shown in Figure 2, the imaging device 1 comprises a substrate 101 and an insulating layer 102. The insulating layer 102 is provided on the substrate 101. The insulating layer 102 is supported by the substrate 101. The insulating layer 102 includes constituent layers 102a, 102b, 102c, 102d, 102e, and 102f.

[0063] The substrate 101 is, for example, a glass substrate, a semiconductor substrate, etc. The semiconductor that the semiconductor substrate 101 may contain is silicon (Si), etc.

[0064] The insulating layer 102 includes, for example, silicon oxide (SiO2). The constituent layers 102a to 102f also include, for example, silicon oxide (SiO2).

[0065] In the pixel region 10, each pixel 100 includes a readout circuit 115. The readout circuit 115 is provided within the substrate 101 and within the insulating layer 102.

[0066] In the pixel region 10, multiple pixel electrodes 104 are provided on the upper main surface, or top surface, of the insulating layer 102 along the Z-axis. The multiple pixel electrodes 104 are arranged two-dimensionally on the top surface of the insulating layer 102 along two axes: the X-axis and the Y-axis perpendicular to the plane of the paper. In other words, the pixel electrodes 104 are arranged in a matrix. These pixel electrodes 104 are arranged at a constant distance from each other. The arrangement of the pixel electrodes 104 corresponds to the arrangement of pixels 100 in Figure 1.

[0067] In the example shown in Figure 2, multiple pixel electrodes 104 are associated one-to-one with multiple readout circuits 115. Each pixel electrode 104 is connected to the corresponding readout circuit 115 by a plug 105.

[0068] In the pixel region 10, a constituent layer 102f is provided in the gap between adjacent pixel electrodes 104. The multiple pixel electrodes 104 have a uniform film thickness, and their upper main surface, i.e., the top surface, is flattened along the Z-axis.

[0069] A photoelectric conversion film 107 is provided on the pixel electrode 104 and the constituent layer 102f. On the photoelectric conversion film 107, a counter electrode 108, a buffer layer 109, and a sealing layer 110 are stacked in order. Multiple color filters 111 and microlenses 113 are provided on the sealing layer 110. In the example in Figure 2, each pixel 100 has one color filter 111 and one microlens 113. The transmission wavelength range of each color filter 111 is set for each pixel 100. In addition, a planarization layer 112 is provided so as to include the portion located between the sealing layer 110 and the microlenses 113.

[0070] The photoelectric conversion film 107 generates an electric charge in response to incident light. The charge generated by the photoelectric conversion film 107 is collected by the pixel electrode 104.

[0071] In this embodiment, the photoelectric conversion film 107 has a constant thickness on the pixel electrode 104 in the pixel region 10. In regions other than on the pixel electrode 104, the thickness of the photoelectric conversion film 107 may be constant or may vary.

[0072] The photoelectric conversion film 107 may include, for example, an organic semiconductor. The photoelectric conversion film 107 may include one or more organic semiconductor layers. For example, in addition to the photoelectric conversion layer that generates hole-electron pairs, the photoelectric conversion film 107 may include a carrier transport layer that transports electrons or holes, a blocking layer that blocks carriers, and the like. Known organic p-type semiconductors and organic n-type semiconductors can be used for the organic semiconductor layers. The photoelectric conversion film 107 may also be, for example, a mixed film of organic donor molecules and acceptor molecules, a mixed film of semiconductor carbon nanotubes and acceptor molecules, or a quantum dot-containing film. The photoelectric conversion film 107 may also include inorganic materials such as amorphous silicon.

[0073] The counter electrode 108 faces the pixel electrode 104. The counter electrode 108 transmits light to the photoelectric conversion film 107.

[0074] The counter electrode 108 contains a light-transmitting conductive material. Examples of conductive materials included in the counter electrode 108 are ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), etc. In this embodiment, the counter electrode 108 mainly contains ITO.

[0075] A counter electrode region is provided on the outer periphery of the pixel region 10. In the counter electrode region, the counter electrode 108 is connected to the connecting electrode 103.

[0076] The plug 105 passes through the constituent layers 102a to 102e. The plug 105 electrically connects each pixel electrode 104 to the corresponding readout circuit 115. Specifically, the plug 105 works in cooperation with the multilayer wiring to electrically connect each pixel electrode 104 to the corresponding readout circuit 115. The top layer wiring 116, which is the top layer wiring of the multilayer wiring, is located above the constituent layer 102d and below the constituent layer 102e.

[0077] The plug 106 passes through the constituent layer 102e. The counter electrode voltage supply unit 18 is located above the constituent layer 102d and below the constituent layer 102e. The plug 106 electrically connects the connecting electrode 103 and the counter electrode voltage supply unit 18. Voltage is applied to the counter electrode 108 via the counter electrode voltage supply unit 18, the plug 106, and the connecting electrode 103 in this order. Note that only a portion of the counter electrode voltage supply unit 18 is shown in Figure 2.

[0078] Plugs 105 and 106 are formed, for example, by embedding conductive material.

[0079] Each readout circuit 115 reads a signal corresponding to the charge collected from the corresponding pixel electrode 104. The readout circuit 115 is constructed using, for example, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or a TFT (Thin Film Transistor). The readout circuit 115 is shielded from light by a light-shielding layer provided, for example, inside the insulating layer 102. In Figure 2, the light-shielding layer is not shown.

[0080] Although not shown in the diagram, a light-shielding layer is provided in areas of the sealing layer 110 other than the area where the color filter 111 is provided. The light-shielding layer blocks external light from reaching areas other than the effective pixel area. This prevents light from entering the photoelectric conversion film 107 in areas other than the effective pixel area.

[0081] In this embodiment, as shown in Figures 1 and 2, one set of combinations consisting of one connecting electrode 103, at least one plug 106, and at least one counter electrode voltage supply unit 18 is electrically connected to one counter electrode 108. However, multiple sets of the above combinations may be electrically connected to one counter electrode 108. The number of sets of the above combinations electrically connected to one counter electrode 108 can be determined by appropriately increasing or decreasing them, taking into account the chip area, wiring width, etc., in the device.

[0082] A peripheral circuit region is provided on the outer periphery of the counter electrode region. Within the peripheral circuit region, peripheral circuits are provided. These peripheral circuits include the vertical driver 12, timing generator 13, signal processing circuit 14, horizontal driver 15, LVDS device 16, serial conversion unit 17, and counter electrode voltage supply unit 18 shown in Figure 1. The metal layer in the peripheral circuit region is formed using, for example, copper (Cu).

[0083] A pad region is provided on the outer periphery of the peripheral circuit region. In the pad region, recesses are provided that penetrate the planarization layer 112, the sealing layer 110, and the buffer layer 109, reaching the upper surface of the constituent layer 102d. A pad 19 is provided on the bottom surface of the recess. Although detailed illustrations are omitted, the pad 19 is electrically connected to various circuits such as signal input / output circuits and voltage supply circuits.

[0084] Next, the imaging mechanism will be explained using Figure 3.

[0085] As shown in Figure 3, light incident from above the Z-axis enters the photoelectric conversion film 107 through the sealing layer 110, the buffer layer 109, and the counter electrode 108. The photoelectric conversion film 107 converts the incident light into electricity and generates charge when an appropriate bias voltage is applied by the pixel electrode 104 and the counter electrode 108. Here, the potential difference between the counter electrode 108 and the pixel electrode 104 becomes the bias voltage applied to the photoelectric conversion film 107. In Figure 3, the charge is represented by white circles.

[0086] As described above, the charge generated by the photoelectric conversion film 107 is transferred from the pixel electrode 104 via the plug 105 to the storage diode 115d in the readout circuit 115, where it is temporarily stored. Then, through the switching operation of transistor elements and other components in the readout circuit 115, it is output to the outside as a signal in a timely manner.

[0087] [1-3. Electrode Configuration, etc.] The configuration of the electrodes in this embodiment will now be described. In the following description, the terms "first electrode" and "second electrode" will be used. The first electrode may correspond to the counter electrode 108. The second electrode may correspond to the pixel electrode 104. The second electrode may correspond to the connecting electrode 103. The first electrode may have the characteristics of the counter electrode 108 described above and below. The second electrode may have the characteristics of the pixel electrode 104 and the connecting electrode 103 described above and below. However, the electrodes that can correspond to the first electrode and the second electrode are not limited to these.

[0088] The imaging device 1 of this embodiment comprises a first electrode, a photoelectric conversion film 107, and a second electrode. The photoelectric conversion film 107 is located below the first electrode. The second electrode is located below the first electrode.

[0089] In this embodiment, the first electrode is the counter electrode 108. When viewed from above, the first electrode and the photoelectric conversion film 107 overlap at least partially. Specifically, when viewed from above, more than 80% of the area of ​​the photoelectric conversion film 107 overlaps with the first electrode. When viewed from above, the entire photoelectric conversion film 107 may overlap with the first electrode.

[0090] In one example, the second electrode is the pixel electrode 104. In this case, the photoelectric conversion film 107 may be placed between the first electrode and the second electrode. In this case, when viewed from above, 80% or more of the area of ​​the second electrode, or the entire area, may overlap with the first electrode. Also in this case, when viewed from above, 80% or more of the area of ​​the second electrode, or the entire area, may overlap with the photoelectric conversion film 107.

[0091] In another example, the second electrode is a connecting electrode 103. In this case, when viewed from above, at least a part of the second electrode, for example, the whole, may be in a position that overlaps with the first electrode. Or, when viewed from above, at least a part of the second electrode, for example, the whole, may be in a position that does not overlap with the first electrode. Also, in this case, when viewed from above, at least a part of the second electrode, for example, the whole, may be in a position that does not overlap with the photoelectric conversion film 107.

[0092] In this embodiment, there is an insulating layer 102 on the substrate 101. A second electrode is located on the insulating layer 102. Specifically, the second electrode is in contact with the insulating layer 102.

[0093] Figures 4A to 4E are schematic cross-sectional views showing the configuration of the second electrode 120 in this embodiment. In the example shown in Figures 4A to 4E, the second electrode 120 is connected to the plug 130. Specifically, the lower surface 120b of the second electrode 120 is connected to the plug 130.

[0094] Plug 130 may correspond to plug 105 or plug 106. Plug 130 may have the features described above and below relating to plug 105. Plug 130 may have the features described above and below relating to plug 106. However, plugs that may correspond to plug 130 are not limited to these.

[0095] In the examples shown in Figures 4A to 4E, the second electrode 120 has a multi-layer structure composed of multiple layers. The uppermost layer 120t of the second electrode 120 contains metal nitride. The second electrode 120 has a first layer 121. The first layer 121 contains tantalum nitride (TaN). Specifically, the uppermost layer 120t of the second electrode 120 contains metal nitride as its main component. The first layer 121 contains tantalum nitride as its main component.

[0096] The second electrode 120 has a multi-layer structure and therefore has not only the first layer 121 but also other layers. These other layers may contain a material with lower electrical resistance than tantalum nitride. As a result, the second electrode 120, having a multi-layer structure, may have lower electrical resistance compared to the case where the first layer 121 is a single layer. Furthermore, these other layers may contain a material that is easier to process than tantalum nitride. As a result, the second electrode 120, having a multi-layer structure, may have higher processability compared to the case where the first layer 121 is a single layer.

[0097] Metal nitrides have high chemical stability. Therefore, the uppermost layer 120t of the second electrode 120 can have high chemical stability. As a result, the second electrode 120 can be protected from chemical reactions by the uppermost layer 120t. This effect can be exerted, for example, when the uppermost layer 120t is exposed to oxygen or high temperature during the manufacturing process of the imaging device 1.

[0098] Tantalum nitride has an amorphous crystalline structure. This amorphous crystalline structure allows for a dense structure. Therefore, in the second electrode 120, the first layer 121 can suppress the diffusion of metals from outside the second electrode 120. In other words, the first layer 121 can provide a barrier property to metals from outside the second electrode 120. This barrier property can be called a metallic barrier property. The metal in question is, for example, copper. That is, the second electrode 120 can have a Cu barrier property based on the first layer 121.

[0099] It should be noted that there are other materials with amorphous crystalline structures besides tantalum nitride. For example, titanium is a material with an amorphous crystalline structure. However, tantalum nitride has high density even among materials with amorphous crystalline structures. For this reason, tantalum nitride has high metal barrier properties among materials with amorphous crystalline structures. Specifically, tantalum nitride has higher density than titanium, and therefore higher metal barrier properties. Generally, in nitrides obtained by adding nitrogen to a single element, nitrogen can contribute to improving density. For this reason, nitrogen in tantalum nitride can contribute to improving density.

[0100] In the examples shown in Figures 4A to 4E, the plug 130 contains metal. In these examples, the plug 130 can extract charge from the second electrode 120 while suppressing the diffusion of metal originating from the plug 130 at the second electrode 120. Specifically, the plug 130 contains metal as its main component.

[0101] In the examples shown in Figures 4A to 4E, the plug 130 contains copper (Cu). In the second electrode 120 of these examples, the diffusion of copper originating from the plug 130 can be suppressed. Furthermore, copper is a material commonly used as multilayer wiring in devices manufactured through semiconductor processes and has high process compatibility. For this reason, the inclusion of copper in the plug 130 is advantageous from the standpoint of reducing manufacturing costs. In this context, the copper is metallic copper. Specifically, the plug 130 contains copper as its main component.

[0102] Plug 130 may contain materials other than copper. For example, plug 130 may contain tungsten. In this context, tungsten refers to metallic tungsten. Plug 130 may contain tungsten as its main component.

[0103] In the examples shown in Figures 4A to 4E, the metal of the plug 130 is in contact with the second electrode 120. Specifically, the copper of the plug 130 is in contact with the second electrode 120. More specifically, the metal of the plug 130 is in contact with the lower surface 120b of the second electrode 120.

[0104] In the examples shown in Figures 4A to 4D, the top layer 120t is the second layer 122. The second layer 122 is a different layer from the first layer 121. The tantalum nitride contained in the first layer 121 is a metal nitride, and therefore has advantages derived from metal nitrides. However, tantalum nitride also has its own disadvantages. In this respect, in the examples shown in Figures 4A to 4D, not only the first layer 121 but also the second layer 122 contains a metal nitride. In these examples, because the second layer 122 contains a metal nitride other than tantalum nitride, it is possible to enjoy the advantages derived from metal nitrides while suppressing the disadvantages derived from tantalum nitride. For example, the top layer 120t can be made of a material that has lower electrical resistance than tantalum nitride. Alternatively, the top layer 120t can be made of a material that is easier to process than tantalum nitride.

[0105] In the examples shown in Figures 4A to 4D, the first layer 121 is thinner than the second layer 122. In this case, the above advantages can be easily enjoyed while suppressing the above disadvantages. However, the thickness of the first layer 121 may be the same as the thickness of the second layer 122. The first layer 121 may also be thicker than the second layer 122.

[0106] The thickness of the first layer 121 is, for example, 5% to 70% of the thickness of the second electrode 122. The thickness of the first layer 121 may also be, for example, 10% to 60% of the thickness of the second electrode 122, or 10% to 40%.

[0107] The thickness of the first layer 121 is, for example, 5 to 70 nm. The thickness of the first layer 121 may also be 10 to 60 nm, or 10 to 40 nm.

[0108] The thickness of the second layer 122 is, for example, 25 to 90 nm. The thickness of the second layer 122 may also be 30 to 90 nm, or 30 to 70 nm.

[0109] The second layer 122 may contain materials different from the first layer 121. Specifically, the second layer 122 may contain a material different from the first layer 121 as its main component. The material different from the first layer 121 is, specifically, a material other than tantalum nitride.

[0110] In the examples shown in Figures 4A to 4D, the second layer 122 contains titanium nitride (TiN). Titanium nitride has lower electrical resistance and is easier to process than tantalum nitride. Therefore, the second layer 122 may be a layer containing a material with lower electrical resistance than tantalum nitride. Furthermore, the second layer 122 may be a layer containing a material that is easier to process than tantalum nitride. Specifically, the second layer 122 contains titanium nitride as its main component.

[0111] In the example shown in Figure 4E, the top layer 120t is the first layer 121. Therefore, the top layer 120t contains tantalum nitride. As a result, the diffusion of metals from external sources into the second electrode 120 can be suppressed in the top layer 120t.

[0112] In the examples shown in Figures 4B, 4D, and 4E, the bottom layer 125 of the second electrode 120 contains metal. These examples demonstrate that the second electrode 120 is easily bonded to a structure containing a material with high bonding affinity to the metal. Specifically, the bottom layer 125 contains metal as its main component.

[0113] In the examples shown in Figures 4B, 4D, and 4E, the bottom layer 125 of the second electrode 120 contains tantalum (Ta). These examples show that the second electrode 120 is easily bonded to structures containing materials with high bonding affinity to tantalum. For example, copper, which may be included in the plug 130, has high bonding affinity to tantalum. In this context, tantalum refers to metallic tantalum. Specifically, the bottom layer 125 contains tantalum as its main component.

[0114] In a typical example, the bottom layer 125 is thinner than the first layer 121. However, the thickness of the bottom layer 125 may be the same as the thickness of the first layer 121. Also, the bottom layer 125 may be thicker than the first layer 121.

[0115] The thickness of the bottom layer 125 is, for example, 5 to 70 nm. The thickness of the bottom layer 125 may also be 10 to 60 nm, or 10 to 40 nm.

[0116] In the examples shown in Figures 4A and 4C, the bottom layer of the second electrode 120 is the first layer 121. Therefore, the bottom layer contains tantalum nitride. As a result, the diffusion of metals from outside the second electrode 120 can be suppressed in the bottom layer.

[0117] In the examples shown in Figures 4C and 4D, the second electrode 120 has a layer 126. The layer 126 contains a material with an amorphous crystalline structure. Therefore, the layer 126 can improve the metal barrier properties of the second electrode 120. Specifically, the layer 126 mainly contains a material with an amorphous crystalline structure.

[0118] In the examples in Figures 4C and 4D, the amorphous crystalline material contained in layer 126 is a material other than tantalum nitride, but it may be tantalum nitride. In one example, layer 126 contains titanium (Ti). Titanium is an example of an amorphous crystalline material. In this context, titanium refers to metallic titanium. Specifically, layer 126 mainly contains tantalum nitride or titanium.

[0119] In a typical example, layer 126 is thinner than the first layer 121. However, the thickness of layer 126 may be the same as the thickness of the first layer 121. Also, layer 126 may be thicker than the first layer 121.

[0120] In one example, the second electrode 120 is the pixel electrode 104. The uppermost layer 120t is the layer closest to the photoelectric conversion film 107 on the pixel electrode 104. As mentioned above, the uppermost layer 120t contains a metal nitride and therefore has high chemical stability. For this reason, this configuration is advantageous from the viewpoint of ensuring the stability of the photoelectric conversion film 107. The upper surface 120a of the second electrode 120 may be in contact with the photoelectric conversion film 107. The metal nitride contained in the uppermost layer 120t is, for example, titanium nitride. The side surface 120s is the surface connecting the upper surface 120a and the lower surface 120b.

[0121] In one example, the second electrode 120 is the connecting electrode 103. The first electrode is the counter electrode 108. The second electrode 120 and the first electrode are electrically connected. The first electrode contains ITO. The top layer 120t contains titanium nitride. The work function of titanium nitride is close to the work function of ITO. This is advantageous from the viewpoint of performing good photoelectric conversion in the photoelectric conversion film 107. Specifically, the first electrode contains ITO as its main component. The top layer 120t contains titanium nitride as its main component.

[0122] The difference between the work function of the second electrode 120, which is the connecting electrode 103, and the work function of the first electrode is, for example, 1.5 eV or less. This difference may also be 1.0 eV or less.

[0123] Figure 5 is a schematic top view showing the configuration of a second electrode 120 according to one example. As shown in Figure 5, when viewed from above, the outer edges of each layer of the multi-layer structure of the second electrode 120 coincide around the entire circumference. In Figure 5, the contour of the connection surface 130m between the plug 130 and the second electrode 120 is shown by a dotted line.

[0124] In the examples shown in Figures 4A and 4E, the second electrode 120 has two layers. A two-layer structure for the second electrode 120 can be simple. This is advantageous from the standpoint of reducing the number of manufacturing steps and manufacturing costs.

[0125] In the examples shown in Figures 4B to 4D, the second electrode 120 has three or more layers. This is advantageous from the viewpoint of giving the second electrode 120 diverse characteristics.

[0126] Specific examples of possible configurations for the second electrode 120 in Figures 4A to 4E are as follows.

[0127] The second electrode 120 in Figure 4A has a two-layer structure in which a first layer 121 mainly composed of tantalum nitride and an uppermost layer 120t mainly composed of titanium nitride are stacked in this order from bottom to top. A plug 130 is connected to the first layer 121.

[0128] The second electrode 120 in Figure 4B has a three-layer structure in which the bottom layer 125, mainly composed of tantalum, the first layer 121, mainly composed of tantalum nitride, and the top layer 120t, mainly composed of titanium nitride, are stacked in this order from bottom to top. A plug 130 is connected to the bottom layer 125.

[0129] The second electrode 120 in Figure 4C has a three-layer structure in which a first layer 121 mainly containing tantalum nitride, a layer 126 mainly containing titanium, and an uppermost layer 120t mainly containing titanium nitride are stacked in this order from bottom to top. A plug 130 is connected to the first layer 121.

[0130] The second electrode 120 in Figure 4D has a four-layer structure, with the bottom layer 125 mainly composed of tantalum, the first layer 121 mainly composed of tantalum nitride, the layer 126 mainly composed of titanium, and the top layer 120t mainly composed of titanium nitride stacked in this order from bottom to top. A plug 130 is connected to the bottom layer 125.

[0131] The second electrode 120 in Figure 4E has a two-layer structure in which a bottom layer 125 containing tantalum as the main component and an uppermost layer 120t functioning as a first layer 121 containing tantalum nitride as the main component are stacked in this order from bottom to top. A plug 130 is connected to the bottom layer 125.

[0132] The materials that may be included in the second electrode 120 are not limited to those listed above. Other materials that may be included in the second electrode 120 include aluminum (Al), tungsten (W), etc. In this context, aluminum refers to metallic aluminum, and tungsten refers to metallic tungsten. The second electrode 120 may contain one of these materials as its main component.

[0133] As can be understood from the above explanation, the second electrode 120 may have a layer containing a metal and a layer containing a metal nitride. Specifically, the second electrode 120 may have a layer mainly containing a metal and a layer mainly containing a metal nitride.

[0134] Furthermore, the second electrode 120 may have at least two layers containing metal nitride. Specifically, the second electrode 120 may have at least two layers containing metal nitride as the main component.

[0135] Here, we will explain "when viewed from above" and "up and down direction." "When viewed from above" has the same meaning as "when viewed through from above." In a typical example, the characteristics of the second electrode 120 when viewed from above correspond to the characteristics of the second electrode 120 when viewed from above. The up and down direction may be the same direction as the thickness direction of the second electrode 120. The up and down direction may be the same direction as the thickness direction of the photoelectric conversion film 107. The up and down direction may be the same direction as the thickness direction of the substrate 101.

[0136] [1-4. Method for manufacturing the imaging device 1] The following describes an example of a manufacturing method for the imaging device 1 according to this embodiment. Figures 6A to 6F are schematic process diagrams showing parts of the manufacturing process of the imaging device 1. In the following description, only the process related to the formation of the pixel electrode 104 will be explained, and the explanation of other processes will be omitted.

[0137] As shown in Figure 6A, the constituent layer 102d and the uppermost wiring 116 form a structure that constitutes the upper surface.

[0138] Next, a constituent layer 102e is formed on the structure shown in Figure 6A by chemical vapor deposition (CVD) or the like. This yields the structure shown in Figure 6B. The constituent layer 102e contains, for example, silicon oxide (SiO2). The thickness of the constituent layer 102e is, for example, 500 nm.

[0139] Next, a first resist pattern having a first via pattern is formed on the constituent layer 102e using lithography. The illustration of the first resist pattern is omitted.

[0140] Next, the constituent layer 102e is etched using the first resist pattern as a mask by dry etching. This forms the first holes 141 in the constituent layer 102e, resulting in the structure shown in Figure 6C.

[0141] Next, the first resist pattern is removed by ashing.

[0142] Next, using a CVD method or sputtering method, tantalum nitride, tantalum, and copper are deposited in that order from above the structure shown in Figure 6C, so as to fill the first hole 141. This forms a first barrier film 105a and a first metal body 105b. The first barrier film 105a has a first outer layer 105a1 and a first inner layer 105a2 located within the first outer layer 105a1. The first metal body 105b is covered from below and from the side by the first inner layer 105a2. The first inner layer 105a2 is covered from below and from the side by the first outer layer 105a1. The first outer layer 105a1 contains tantalum nitride. The first inner layer 105a2 contains tantalum. The first metal body 105b contains copper. The first metal body 105b is columnar.

[0143] After the above deposition process, excess tantalum nitride, tantalum, and copper are deposited on the upper surface 102e1 of the constituent layer 102e. These excess materials are removed by polishing using chemical mechanical polishing (CMP). In this way, a structure is obtained in which a plug 105 containing the first barrier film 105a and the first metal body 105b is formed and the excess materials are removed, as shown in Figure 6D.

[0144] Furthermore, with respect to the first barrier film 105a, the material of the first outer layer 105a1 may be changed from tantalum nitride to titanium nitride (TiN), and the material of the first inner layer 105a2 may be changed from tantalum to titanium (Ti). The material of the first metal body 105b may be changed from copper to tungsten (W).

[0145] On the structure shown in Figure 6D, tantalum nitride and titanium nitride are sequentially deposited by CVD or physical vapor deposition (PVD). This forms a laminate 104x on the plugs 105 and constituent layer 102e, resulting in the structure shown in Figure 6E. The laminate 104x includes a lower layer 104ax containing tantalum nitride and an upper layer 104bx containing titanium nitride. The total film thickness of the laminate 104x is, for example, 100 nm. When viewed from above, the laminate 104x extends across multiple plugs 105.

[0146] Next, a second resist pattern having a pixel electrode pattern is formed on the laminate 104x using lithography. The second resist pattern is not shown in the diagram.

[0147] Next, the laminate 104x is etched by dry etching, using the second resist pattern as a mask. This divides the laminate 104x into multiple parts. Thus, a structure shown in Figure 6F is obtained in which multiple pixel electrodes 104 are formed on the constituent layer 102e. In this structure, the multiple pixel electrodes 104 are spaced apart from each other, and each pixel electrode 104 is connected to a corresponding plug 105. Each pixel electrode 104 includes a lower layer 104a containing tantalum nitride and an upper layer 104b containing titanium nitride. The top surface of the pixel electrode 104 is planarized by etching from above in a later process.

[0148] Next, the second resist pattern is removed by ashing. The ashing gas is oxygen. Specifically, in this ashing process, the second resist pattern is removed using oxygen plasma.

[0149] The materials used for the laminate 104x are not limited to those described above. Materials that may be included in the laminate 104x can be selected from etchable materials. Examples of etchable materials include tantalum nitride (TaN) and titanium nitride (TiN), as well as titanium (Ti), tantalum (Ta), aluminum (Al), tungsten (W), etc.

[0150] In this embodiment, plug 106 is formed in the same manner as plug 105. Specifically, plug 106 and plug 105 can be manufactured together in the same process. Plug 106 has the same configuration as plug 105. Specifically, plug 106 is made of the same material as plug 105. The connecting electrode 103 is formed in the same manner as pixel electrode 104. Specifically, the connecting electrode 103 and pixel electrode 104 can be manufactured together in the same process. The connecting electrode 103 has the same configuration as pixel electrode 104. Specifically, the connecting electrode 103 is made of the same material as pixel electrode 104. These points are also the same in the embodiments described later.

[0151] However, the manufacturing method of plug 106 may differ from that of plug 105. Plug 106 and plug 105 do not have to be manufactured together in the same process. Plug 106 may have a different configuration from plug 105. The manufacturing method of connecting electrode 103 may differ from that of pixel electrode 104. Connecting electrode 103 and pixel electrode 104 do not have to be manufactured together in the same process. Connecting electrode 103 may have a different configuration from pixel electrode 104. These points are also true in the embodiments described later.

[0152] The following configuration may also be adopted: namely, there are multiple second electrodes 120. These multiple second electrodes 120 include a third electrode and a fourth electrode. The first layer 121 of the third electrode is thicker than the first layer 121 of the fourth electrode. With this configuration, it is easier to make the metal barrier properties of the third electrode higher than those of the fourth electrode.

[0153] The third electrode corresponds to, for example, the connecting electrode 103. The fourth electrode corresponds to, for example, the pixel electrode 104.

[0154] The thickness of the first layer 121 of the third electrode may be the same as the thickness of the first layer 121 of the fourth electrode. The first layer 121 of the third electrode may be thinner than the first layer 121 of the fourth electrode.

[0155] The second layer 122 of the third electrode may be thicker than the second layer 122 of the fourth electrode. The thickness of the second layer 122 of the third electrode may be the same as the thickness of the second layer 122 of the fourth electrode. The second layer 122 of the third electrode may be thinner than the second layer 122 of the fourth electrode.

[0156] The top layer 120t of the third electrode may be thicker than the top layer 120t of the fourth electrode. The thickness of the top layer 120t of the third electrode may be the same as the thickness of the top layer 120t of the fourth electrode. The top layer 120t of the third electrode may be thinner than the top layer 120t of the fourth electrode.

[0157] The bottom layer 125 of the third electrode may be thicker than the bottom layer 125 of the fourth electrode. The thickness of the bottom layer 125 of the third electrode may be the same as the thickness of the bottom layer 125 of the fourth electrode. The bottom layer 125 of the third electrode may be thinner than the bottom layer 125 of the fourth electrode.

[0158] The third electrode layer 126 may be thicker than the fourth electrode layer 126. The thickness of the third electrode layer 126 may be the same as the thickness of the fourth electrode layer 126. The third electrode layer 126 may be thinner than the fourth electrode layer 126.

[0159] [1-5. Manifestation of Cu barrier properties in electrodes] As described above, the manufacturing method of the imaging device 1 includes a step of removing the second resist pattern by ashing. In this ashing, the upper surface of the pixel electrode 104 is exposed to oxygen, which is the ashing gas.

[0160] Here, the copper in plug 105 can diffuse into pixel electrode 104. This diffusion can cause problems such as abnormal oxidation of the copper. Below, we will explain the function of suppressing the diffusion of copper within pixel electrode 104, i.e., the Cu barrier property. Figures 7A and 7B are schematic cross-sectional views showing the abnormal oxidation of copper.

[0161] Let's assume that the pixel electrode 154 does not contain tantalum nitride but instead contains titanium nitride. Specifically, as shown in Figure 7A, let's assume that the pixel electrode 154 has a structure in which a titanium nitride layer 154b is placed on a titanium layer 154a. Titanium nitride has a columnar crystal structure. It is difficult to achieve a dense structure with a columnar crystal structure. For this reason, the Cu barrier properties of titanium nitride are low. Also, the Cu barrier properties of titanium cannot be said to be sufficiently high. For this reason, the copper from the plug 105 diffuses into the pixel electrode 154 and also diffuses within the pixel electrode 154. Further investigation is needed for details, but it is thought that exposing the surface of the pixel electrode 154 to oxygen plasma promotes the diffusion of copper from the plug 105 to the pixel electrode 154 and the diffusion of copper within the pixel electrode 154.

[0162] When the upper surface of the pixel electrode 154 is exposed to ashing gas, i.e., oxygen, while copper is diffused on its surface, the copper undergoes abnormal oxidation. Thus, as schematically shown in Figure 7A, a mass 155 of copper oxide can form on the upper surface of the pixel electrode 154. The mass 155 has, for example, a roughly hemispherical shape. When a mass 155 of copper oxide forms, various problems can occur.

[0163] For example, after ashing, a photoelectric conversion film 107 is formed on the pixel electrode 154 and the aggregate 155, as shown in Figure 7B. Copper atoms in the aggregate 155 diffuse into the photoelectric conversion film 107, acting as trap levels and potentially degrading the leakage characteristics of the photoelectric conversion film 107. Specifically, a current leakage path is formed in the photoelectric conversion film 107, making it easier for leakage current to flow. Furthermore, the diffusion of copper atoms into the photoelectric conversion film 107 reduces the sensitivity and reliability of the photoelectric conversion film 107.

[0164] The pixel electrode described in Patent Document 1 has a TiN / Ti structure. The above-mentioned problem can also occur during the manufacturing process of an imaging device in which a copper-containing plug is connected to this pixel electrode.

[0165] In contrast, in this embodiment, the pixel electrode 104 contains tantalum nitride. Tantalum nitride has an amorphous crystalline structure, which makes it easy to achieve a dense structure. Therefore, tantalum nitride has high Cu barrier properties. For this reason, in the pixel electrode 104 of this embodiment, it is unlikely that copper from the plug 105 will diffuse to the upper surface of the pixel electrode 104. Therefore, it is unlikely that clumps of copper oxide will form on the upper surface of the pixel electrode 104. This suppresses the deterioration of the leakage characteristics of the photoelectric conversion film 107 and suppresses the decrease in the sensitivity and reliability of the photoelectric conversion film 107.

[0166] Furthermore, in this embodiment, the connecting electrode 103 contains tantalum nitride. Therefore, in the connecting electrode 103 of this embodiment, it is unlikely that copper from the plug 106 will diffuse to the upper surface of the connecting electrode 103. Therefore, it is unlikely that clumps of copper oxide will form on the upper surface of the connecting electrode 103. Therefore, it is unlikely that the connection between the connecting electrode 103 and the counter electrode 108 in the counter electrode region will be obstructed by the clumps of copper oxide. In addition, it is unlikely that the electrical resistance in the electrical path to the counter electrode 108 will increase due to the clumps of copper oxide.

[0167] Other embodiments will be described below. In the following, elements common to embodiments already described and those described later will be given the same reference numerals, and their descriptions may be omitted. The descriptions of each embodiment may be mutually applicable, insofar as they do not conflict with technical standards. Insofar as they do not conflict with technical standards, each embodiment may be combined with another.

[0168] (Second Embodiment) In the second embodiment, an electrode having an insulating film is used. The second embodiment will be described below.

[0169] [2-3. Electrode Configuration, etc.] Figures 8A and 8B are schematic cross-sectional views showing the configuration of the second electrode 220 in this embodiment. In the example shown in Figures 8A and 8B, the second electrode 220 is connected to the plug 130. Specifically, the lower surface 220b of the second electrode 220 is connected to the plug 130.

[0170] In the examples shown in Figures 8A and 8B, the second electrode 220 comprises an electrode body 224 and an insulating film 225. The electrode body 224 ensures an electrical path in the second electrode 220. The insulating film 225 has high density. Therefore, the insulating film 225 can suppress the diffusion of metals from the outside of the second electrode 220. In other words, the insulating film 225 can provide a metal barrier to metals from the outside of the second electrode 220. For example, the second electrode 220 has Cu barrier properties based on the insulating film 225.

[0171] In the examples shown in Figures 8A and 8B, the conductivity of the electrode body 224 is higher than that of the insulating film 225.

[0172] In the example shown in Figure 8A, the insulating film 225 is surrounded by the electrode body 224 from above, below, and the sides. In this context, "surrounded" specifically means completely enclosing without any gaps. More specifically, the entire surface of the insulating film 225 is in contact with the electrode body 224.

[0173] In the example shown in Figure 8B, the insulating film 225 constitutes a portion of the upper surface of the second electrode 220. On the other hand, the insulating film 225 is not exposed on the lower surface of the second electrode 220.

[0174] The insulating film 225 may not be exposed on the upper surface of the second electrode 220, while the insulating film 225 may constitute a part of the lower surface of the second electrode 220.

[0175] In the examples shown in Figures 8A and 8B, at least a portion of the upper surface 220t of the second electrode 220 is formed by the electrode body 224. At least a portion of the lower surface 220b of the second electrode 220 is also formed by the electrode body 224. This configuration ensures an electrical path from the lower surface 220b to the upper surface 220t of the second electrode 220.

[0176] In the example shown in Figure 8A, specifically, the entire upper surface 220t of the second electrode 220 is composed of the electrode body 224. The entire lower surface 220b of the second electrode 220 is also composed of the electrode body 224.

[0177] In the example shown in Figure 8B, specifically, only a portion of the upper surface 220t of the second electrode 220 is formed by the electrode body 224. The entire lower surface 220b of the second electrode 220 is formed by the electrode body 224.

[0178] However, the entire upper surface 220t of the second electrode 220 may be composed of the electrode body 224, and only a portion of the lower surface 220b of the second electrode 220 may be composed of the electrode body 224. Alternatively, only a portion of the upper surface 220t of the second electrode 220 may be composed of the electrode body 224, and only a portion of the lower surface 220b of the second electrode 220 may be composed of the electrode body 224.

[0179] In the examples of Figures 8A and 8B, the electrode body 224 includes a first layer 221 and a second layer 222. In the examples of Figures 8A and 8B, the second layer 222 is on top of the first layer 221. The electrode body 224 may have layers other than the first layer 221 and the second layer 222.

[0180] In the examples shown in Figures 8A and 8B, at least a portion of the upper surface 220t of the second electrode 220 is composed of the second layer 222. At least a portion of the lower surface 220b of the second electrode 220 is composed of the first layer 221.

[0181] In the example shown in Figure 8A, specifically, the entire upper surface 220t of the second electrode 220 is composed of the second layer 222, and the entire lower surface 220b of the second electrode 220 is composed of the first layer 221.

[0182] In the example shown in Figure 8B, specifically, only a portion of the upper surface 220t of the second electrode 220 is composed of the second layer 222. The entire lower surface 220b of the second electrode 220 is composed of the first layer 221.

[0183] However, the entire upper surface 220t of the second electrode 220 may be composed of the second layer 222, and only a portion of the lower surface 220b of the second electrode 220 may be composed of the first layer 221. Alternatively, only a portion of the upper surface 220t of the second electrode 220 may be composed of the second layer 222, and only a portion of the lower surface 220b of the second electrode 220 may be composed of the first layer 221.

[0184] In the examples shown in Figures 8A and 8B, at least a portion of the side surface 220s of the second electrode 220 is composed of the electrode body 224. Specifically, the entire side surface 220s of the second electrode 220 is composed of the electrode body 224. However, only a portion of the side surface 220s of the second electrode 220 may be composed of the electrode body 224. Note that the side surface 220s is the surface connecting the upper surface 220t and the lower surface 220b.

[0185] Figure 9 is a schematic cross-sectional view showing the configuration of a second electrode 220 according to one example. In the examples of Figures 8A and 8B, as shown in Figure 9, the electrode body 224 and the insulating film 225 appear in a cross-section perpendicular to the vertical direction. Specifically, in a cross-section perpendicular to the vertical direction, the insulating film 225 is surrounded by the electrode body 224. In the second electrode 220 according to this example, the diffusion of metal from the outside of the second electrode 220 can be suppressed while suppressing an increase in the resistance value of the second electrode 220. More specifically, in a cross-section perpendicular to the vertical direction, the insulating film 225 is surrounded by the second layer 222. However, in a cross-section perpendicular to the vertical direction, the insulating film 225 may also be surrounded by the first layer 221. In this context, "surrounded" specifically means surrounding without any gaps.

[0186] In the examples shown in Figures 8A and 8B, the first layer 221 is placed between the plug 130 and the insulating film 225. The insulating film 225 contains an oxide. The first layer 221 contains a non-oxide. In this example, the insulating properties of the insulating film 225 can be ensured by the oxide. On the other hand, the metal in the plug 130 is less likely to react with the oxide derived from the insulating film 225. This is advantageous from the viewpoint of suppressing the deterioration of the characteristics of the plug 130. Examples of non-oxides include metals and metal nitrides. Specifically, the insulating film 225 mainly contains an oxide. The first layer 221 mainly contains a non-oxide.

[0187] Figures 10A and 10B are schematic top views showing the configuration of the second electrode 220. In the examples of Figures 8A and 8B, as shown in Figures 10A and 10B respectively, when viewed from above, at least a portion of the insulating film 225 and at least a portion of the connection surface 130m between the plug 130 and the second electrode 220 overlap. This configuration makes it easier to suppress the diffusion of metal originating from the plug 130 in the second electrode 220.

[0188] In the configurations shown in Figures 10A and 10B, specifically, when viewed from above, the entire connection surface 130m of the plug 130 with the second electrode 220 overlaps with the insulating film 225. More specifically, in the configurations shown in Figures 10A and 10B, when viewed from above, the entire contour 225m of the insulating film 225 is located outside the connection surface 130m. However, when viewed from above, only a portion of the connection surface 130m of the plug 130 with the second electrode 220 may overlap with the insulating film 225.

[0189] In Figures 10A and 10B, the position of the contour of the connection surface 130m between the plug 130 and the second electrode 220 is indicated by a dotted line. Also, in Figure 10A, the position of the contour 225m of the insulating film 225 is indicated by a dotted line.

[0190] As described above, in the examples of Figures 8A and 8B, the second layer 222 constitutes at least a portion of the upper surface 220t of the second electrode 220. In this way, the second layer 222 can impart the desired characteristics to the upper surface 220t of the second electrode 220. Specifically, in the example of Figure 8A, the second layer 222 constitutes the entire upper surface 220t of the second electrode 220. In the example of Figure 8B, the second layer 222 constitutes only a portion of the upper surface 220t of the second electrode 220.

[0191] For example, by using a layer containing titanium nitride as the second layer 222, conductivity and chemical stability can be provided to the upper surface 220t of the second electrode 220. Furthermore, if the first electrode contains ITO, then by using a layer containing titanium nitride as the second layer 222, the work function of the material in the first electrode and the work function of the material in the second layer 222 can be made close. The second layer 222 may contain titanium nitride as its main component.

[0192] In the example shown in Figure 8A, the insulating film 225 is located between the first layer 221 and the second layer 222. Specifically, the insulating film 225 is located between the first layer 221 and the second layer 222 in the vertical direction. The second electrode 220 in this example can be manufactured through a manufacturing process in which the first layer 221, the insulating film 225, and the second layer 222 are provided in this order. In this case, the density of the insulating film 225 makes it easier to ensure the stability of the upper surface of the first layer 221 located below the insulating film 225. It also makes it easier to stabilize the crystallinity of the second layer 222 located above the insulating film 225.

[0193] In the example shown in Figure 8B, the second layer 222 is frame-shaped when viewed from above. The insulating film 225 is positioned inside this frame-shaped structure when viewed from above.

[0194] In the examples shown in Figures 8A and 8B, the insulating film 225 penetrates only the first layer 221. However, the insulating film 225 may penetrate only the second layer 222. Alternatively, the insulating film 225 may penetrate both the first layer 221 and the second layer 222.

[0195] In the examples shown in Figures 8A and 8B, as shown in Figures 10A and 10B respectively, when viewed from above, the outer edges of each layer of the electrode body 224 of the second electrode 220 coincide around the entire circumference.

[0196] In the examples shown in Figures 8A and 8B, the thickness of the insulating film 225 is 10 nm or more. A thickness of this thickness in the insulating film 225 makes it easier to ensure the diffusion-suppressing effect, i.e., the metal barrier properties. The thickness of the insulating film 225 may also be 15 nm or more.

[0197] The thickness of the insulating film 225 is, for example, 70 nm or less. The thickness of the insulating film 225 may be 50 nm or less, or 40 nm or less.

[0198] The insulating film 225 may be thinner than the first layer 221. The thickness of the insulating film 225 may be the same as the thickness of the first layer 221. The insulating film 225 may be thicker than the first layer 221.

[0199] The insulating film 225 may have a single-layer structure or a multi-layer structure.

[0200] Examples of insulating materials that may be included in the insulating film 225 include silicon oxide, silicon nitride, alumina (ALO), and tetraethoxysilane (TEOS). The insulating film 225 may contain one of these materials as its main component.

[0201] In the examples of Figures 8A and 8B, the metal of the plug 130 is in contact with the second electrode 220. Specifically, the copper of the plug 130 is in contact with the second electrode 220. More specifically, the metal of the plug 130 is in contact with the lower surface 220b of the second electrode 220.

[0202] The thickness of the first layer 221 is, for example, 5 to 70 nm. The thickness of the first layer 221 may also be 10 to 60 nm, or 10 to 40 nm.

[0203] The thickness of the second layer 222 is, for example, 25 to 90 nm. The thickness of the second layer 222 may also be 30 to 90 nm, or 30 to 70 nm.

[0204] Examples of materials that may be included in the electrode body 224 include metals and metal nitrides. Examples of metals include titanium (Ti), tantalum (Ta), aluminum (Al), and tungsten (W). Examples of metal nitrides include tantalum nitride (TaN) and titanium nitride (TiN). The electrode body 224 may contain one of these materials as its main component.

[0205] The material that may be included in the first layer 221 is the same as the material that may be included in the electrode body 224. The material that may be included in the second layer 222 is the same as the material that may be included in the electrode body 224. The material that may be included in the first layer 221 and the material that may be included in the second layer 222 may be the same or different.

[0206] Specific examples of possible configurations for the second electrode 220 in Figures 8A and 8B are as follows.

[0207] In the second electrode 220 shown in Figures 8A and 8B, a first layer 221 mainly composed of tantalum and a second layer 222 mainly composed of tantalum nitride are stacked in this order from bottom to top.

[0208] In the second electrode 220 shown in Figures 8A and 8B, a first layer 221 mainly composed of titanium and a second layer 222 mainly composed of titanium nitride may be stacked in this order from bottom to top.

[0209] In the second electrode 220 shown in Figures 8A and 8B, a first layer 221 containing tantalum nitride as the main component and a second layer 222 containing titanium nitride as the main component may be stacked in this order from bottom to top.

[0210] The specific configuration of the second electrode 220 is not limited to the configurations shown in Figures 8A and 8B. For example, the configuration of the laminate of the first molded body 228, insulating film 225, and second molded body 229 shown in Figure 11D can be considered a possible configuration for the second electrode 220.

[0211] The insulating film 225 can provide a metal barrier. For this reason, the configuration of the second electrode 220 may be adopted in electrodes located in areas where a metal barrier is particularly necessary. In one specific example, the pixel electrode 104 does not have an insulating film, while the connecting electrode 103 has the configuration of the second electrode 220. However, it is also possible that the pixel electrode 104 has the configuration of the second electrode 220, while the connecting electrode 103 does not have an insulating film. Furthermore, both the pixel electrode 104 and the connecting electrode 103 may have the configuration of the second electrode 220.

[0212] The following configuration may also be adopted: namely, there are multiple second electrodes 220. These multiple second electrodes 220 include a third electrode and a fourth electrode. The insulating film 225 of the third electrode is thicker than the insulating film 225 of the fourth electrode. With this configuration, it is easier to make the metal barrier properties of the third electrode higher than those of the fourth electrode.

[0213] The third electrode corresponds to, for example, the connecting electrode 103. The fourth electrode corresponds to, for example, the pixel electrode 104.

[0214] The thickness of the insulating film 225 of the third electrode may be the same as the thickness of the insulating film 225 of the fourth electrode. The insulating film 225 of the third electrode may be thinner than the insulating film 225 of the fourth electrode.

[0215] The first layer 221 of the third electrode may be thicker than the first layer 221 of the fourth electrode. The thickness of the first layer 221 of the third electrode may be the same as the thickness of the first layer 221 of the fourth electrode. The first layer 221 of the third electrode may be thinner than the first layer 221 of the fourth electrode.

[0216] The second layer 222 of the third electrode may be thicker than the second layer 222 of the fourth electrode. The thickness of the second layer 222 of the third electrode may be the same as the thickness of the second layer 222 of the fourth electrode. The second layer 222 of the third electrode may be thinner than the second layer 222 of the fourth electrode.

[0217] [2-4-1. Method for manufacturing the imaging device 1] The following describes an example of a manufacturing method for the imaging device 1 according to this embodiment. Figures 11A to 11C are schematic process diagrams showing a part of the manufacturing process of the imaging device 1, respectively. In the following description, only the process related to the formation of the pixel electrode 104 will be explained, and the explanation of other processes will be omitted.

[0218] Following the explanation in "1-4. Method for Manufacturing the Imaging Device 1" of the first embodiment, the structure shown in Figure 6F is fabricated.

[0219] At this stage, the pixel electrode 104 as described in the first embodiment is formed. In this embodiment, the pixel electrode 104 as described in the first embodiment is referred to as the first molded body 228.

[0220] On the structure shown in Figure 6F, alumina, silicon nitride, and silicon oxide are sequentially deposited by CVD or physical vapor deposition (PVD). This forms a laminate 225x on the first molded body 228 and the constituent layer 102e, resulting in the structure shown in Figure 11A. In the laminate 225x, a layer 225ax containing alumina, a layer 225bx containing silicon nitride, and a layer 225cx containing silicon oxide are stacked in this order from bottom to top. When viewed from above, the laminate 225x extends to span multiple plugs 105.

[0221] Next, a third resist pattern is formed on the 225x laminate using lithography. The third resist pattern is not shown in the diagram.

[0222] Next, the laminate 225x is etched by dry etching, using the third resist pattern as a mask. This divides the laminate 225x into multiple parts. Thus, a structure shown in Figure 11B is obtained in which one insulating film 225 is formed on each first molded body 228. In the insulating film 225, a layer 225a containing alumina, a layer 225b containing silicon nitride, and a layer 225c containing silicon oxide are stacked in this order from bottom to top.

[0223] Next, tantalum nitride and titanium nitride are sequentially deposited on the structure shown in Figure 11B by CVD or physical vapor deposition (PVD). This forms a laminate 229x on the insulating film 225, the first molded body 228, and the constituent layer 102e, resulting in the structure shown in Figure 11C. The laminate 229x includes a lower layer 229ax containing tantalum nitride and an upper layer 229bx containing titanium nitride. The total film thickness of the portion of the laminate 229x on the insulating film 225 is, for example, 50 nm. When viewed from above, the laminate 229x extends across multiple plugs 105.

[0224] Next, a second resist pattern having a pixel electrode pattern is formed on the laminate 229x using lithography. The second resist pattern is not shown in the diagram.

[0225] Next, the laminate 229x is etched by dry etching using the second resist pattern as a mask. This divides the laminate 229x into multiple parts. Thus, the structure shown in Figure 11D is obtained in which the second molded body 229 is formed on the insulating film 225 and the first molded body 228. The second molded body 229 includes a lower layer 229a containing tantalum nitride and an upper layer 229b containing titanium nitride. In this structure, the first molded body 228, the insulating film 225 and the second molded body 229 constitute the pixel electrode 104 of the second embodiment. In this structure, there are multiple pixel electrodes 104. The multiple pixel electrodes 104 are spaced apart from each other, and each pixel electrode 104 is connected to a corresponding plug 105. The top surface of the pixel electrode 104 is flattened by etching from above in a later process.

[0226] The lower layer 104a of the first molded body 228 may correspond to the first layer 221. The upper layer 104b of the first molded body 228 may correspond to the first layer 221. The lower layer 229a of the second molded body 229 may correspond to the second layer 222. The upper layer 229b of the second molded body 229 may correspond to the second layer 222.

[0227] [2-4-2. Method for manufacturing the imaging device 1] The following describes another example of the manufacturing method of the imaging device 1 according to this embodiment. Figures 12A to 12D are schematic process diagrams showing a part of the manufacturing process of the imaging device 1, respectively. In the following description, only the process related to the formation of the pixel electrode 104 will be described, and the description of other processes will be omitted.

[0228] The structure shown in Figure 6D is fabricated according to the description in "1-4. Method for Manufacturing the Imaging Device 1" of the first embodiment.

[0229] Titanium (Ti) and tetraethoxysilane (TEOS) are sequentially deposited on the structure shown in Figure 6D by CVD or physical vapor deposition (PVD). This forms a lower layer 104px on top of the plug 105 and constituent layer 102e, and a middle layer 104qx on top of the lower layer 104px. Thus, the structure shown in Figure 12A is obtained. The lower layer 104px contains titanium. The middle layer 104qx contains tetraethoxysilane. The lower layer 104px and the middle layer 104qx extend across multiple plugs 105 when viewed from above.

[0230] Next, a third resist pattern is formed on the intermediate layer 104qx using lithography. The illustration of the third resist pattern is omitted.

[0231] Next, the middle layer 104qx is etched by dry etching, using the third resist pattern as a mask. This divides the middle layer 104qx into multiple parts. In this way, a structure shown in Figure 12B is obtained in which multiple insulating films 225 are formed on the lower layer 104px.

[0232] Next, titanium nitride (TiN) is deposited on the structure shown in Figure 12B by CVD or physical vapor deposition (PVD). This forms an upper layer 104rx on top of the lower layer 104px and insulating film 225, resulting in the structure shown in Figure 12C. The upper layer 104rx contains titanium nitride. When viewed from above, the upper layer 104rx extends across multiple plugs 105.

[0233] Next, a second resist pattern having a pixel electrode pattern is formed on the upper layer 104rx using lithography. The second resist pattern is not shown in the diagram.

[0234] Next, the lower layer 104px and upper layer 104rx are etched by dry etching, using the second resist pattern as a mask. This divides the combination of the lower layer 104px, multiple insulating films 225, and upper layer 104rx into multiple parts. In this way, multiple pixel electrodes 104 are formed as shown in Figure 12D. In each pixel electrode 104, a second layer 222 is provided on top of a first layer 221, and an insulating film 225 is placed between these first and second layers 221 and 222. The first layer 221 contains titanium. The second layer 222 contains titanium nitride. The multiple pixel electrodes 104 are spaced apart from each other, and each pixel electrode 104 is connected to a corresponding plug 105. The top surface of the pixel electrode 104 is planarized by etching from above in a later process.

[0235] (Third embodiment) In the third embodiment, an example of a method for manufacturing the imaging device 1, applicable to the first and second embodiments, will be described. Figures 13A to 13E are schematic process diagrams showing parts of the manufacturing process of the imaging device 1, respectively. In the following description, the process of forming the photoelectric conversion film by etching will be described, and the description of other processes will be omitted.

[0236] [3-4. Method for manufacturing the imaging device 1] As shown in Figure 13A, the pixel electrode 104, the constituent layer 102f, and the connecting electrode 103 form a structure that constitutes the upper surface. In this structure, a plug 105 is connected to the lower surface of the pixel electrode 104. A plug 106 is connected to the lower surface of the connecting electrode 103. These plugs 105 and 106 pass through the constituent layer 102e.

[0237] Layer 107x is deposited on the structure shown in Figure 13A. Layer 107x can be formed by methods such as spin coating, inkjet printing, die coating, spray coating, vacuum deposition, or screen printing. Layer 107x is patterned into a predetermined shape in a later process to become the photoelectric conversion film 107. The material of layer 107x can be appropriately determined according to the material of the photoelectric conversion film 107 to be obtained.

[0238] Next, layer 108x is formed on layer 107x. Layer 108x is formed, for example, by sputtering. Layer 108x is patterned into a predetermined shape in a later process to become the counter electrode 108. The material of layer 108x can be appropriately determined according to the material of the counter electrode 108 to be obtained.

[0239] Next, layer 109x is formed on layer 108x. Layer 109x can be formed by, for example, atomic layer deposition (ALD), chemical vapor deposition (CVD), or sputtering. Layer 109x is patterned into a predetermined shape in a later process to become a buffer layer 109. The material of layer 109x can be appropriately determined according to the material of the buffer layer 109 to be obtained.

[0240] Figure 13B shows the structure in which layers 107x, 108x, and 109x are formed.

[0241] Next, a photoresist is applied to layer 109x, and using photolithography or the like, the applied photoresist 195 is left only in the areas corresponding to the later photoelectric conversion film 107.

[0242] Figure 13C shows the structure on which the photoresist 195 is formed.

[0243] Next, the portions of layers 107x, 108x, and 109x that are not covered by the photoresist 195 are removed by etching. This forms the photoelectric conversion film 107, counter electrode 108, and buffer layer 109, which are patterned to a predetermined shape.

[0244] In this embodiment, the etching of layers 107x, 108x, and 109x is performed by dry etching.

[0245] In etching layers 108x and 109x, photoresist 195 is used as a mask. Etching of layers 108x and 109x is performed using a gas containing halogens such as fluorine, chlorine, bromine, and iodine. By using a gas containing at least one of fluorine and chlorine, accurate patterning can be achieved. Dry etching is performed using reactive etching (RIE), in which the gas is plasma-converted by plasma discharge, and the chemical species of the plasma-converted gas react with layers 108x and 109x. When layers 108x and 109x are formed using a material containing nitrogen or silicon, these gases and etching methods can be used to efficiently etch layers 108x and 109x.

[0246] Layers 108x and 109x are etched to form the counter electrode 108 and the buffer layer 109.

[0247] Figure 13D shows the structure obtained by etching layers 108x and 109x.

[0248] In etching layer 107x, buffer layer 109 is used as a mask. The material of buffer layer 109 can be selected so that it can function as a mask. Examples of such materials include silicon oxynitride (SiON). Etching of layer 107x is performed using an oxygen-containing gas. Specifically, an oxygen-containing gas is filled into a chamber, and a portion of layer 107x is oxidized by chemical etching through an oxidation reaction. In this embodiment, since layer 107x contains a large amount of carbon, it can be removed as carbon oxide through an oxidation reaction with oxygen gas.

[0249] The photoelectric conversion film 107 is formed by etching layer 107x. The structure obtained by etching layer 107x is shown in Figure 13E.

[0250] Thereafter, a wiring for electrically connecting the counter electrode 108 and the connection electrode 103 is formed. This wiring can be formed by an appropriate method. For example, a through hole is provided in the buffer layer 109, and the wiring can be formed so as to connect the upper surface of the counter electrode 108 and the upper surface of the connection electrode 103 through the through hole. The through hole can be formed by photolithography and etching. The wiring can be formed by combining sputtering, vacuum evaporation method, etching, etc. It is also possible to form the wiring so as to connect the side surface of the counter electrode 108 and the upper surface of the connection electrode 103 without providing a through hole. The wiring may be provided so as to connect the upper surface of the counter electrode 108 and the upper surface of the connection electrode 103 through the through hole and also connect the side surface of the counter electrode 108 and the upper surface of the connection electrode 103.

[0251] Specific examples of the method of etching the photoelectric conversion film, specific examples of the method of electrically connecting the counter electrode 108 and the connection electrode 103, etc. are described in, for example, Patent Document 2.

[0252] [3-5. Expression of Cu barrier property in electrodes] As described above, the manufacturing method of the imaging device 1 of the third embodiment includes a step of forming the photoelectric conversion film 107 by etching the layer 107x using a gas containing oxygen. In this etching, the upper surface of the connection electrode 103 is exposed to oxygen.

[0253] Here, the copper of the plug 106 can diffuse into the connection electrode 103. Due to this diffusion, problems such as abnormal oxidation of copper may occur. Hereinafter, the action of suppressing the diffusion of copper in the pixel electrode 104, that is, the Cu barrier property, will be described. FIG. 14 is a schematic cross-sectional view showing a state where copper is abnormally oxidized.

[0254] Suppose that the connection electrode 153 does not contain tantalum nitride or an insulating film, but instead contains titanium nitride. As described in the first embodiment, the Cu barrier property of titanium nitride is low. Therefore, the copper of the plug 106 diffuses into the connection electrode 153 and also diffuses within the connection electrode 153.

[0255] When the upper surface of the connecting electrode 153 is exposed to oxygen while copper is diffused on its surface, the copper undergoes abnormal oxidation. Thus, as schematically shown in Figure 14, a mass 155 of copper oxide can form on the upper surface of the connecting electrode 153. The mass 155 may, for example, have a roughly hemispherical shape. The formation of this copper oxide mass 155 can lead to various problems.

[0256] For example, as described above, after the process of forming the photoelectric conversion film 107 by etching, as shown in Figure 13E, wiring is formed to electrically connect the upper surface of the connecting electrode 103 and the counter electrode 108. At this time, as shown in Figure 14, if a mass of copper oxide 155 is present on the upper surface of the connecting electrode 153, the mass of copper oxide 155 may obstruct the connection between the connecting electrode 153 and the wiring, or increase the electrical resistance at the connection between the connecting electrode 153 and the wiring.

[0257] In contrast, in this embodiment, the connecting electrode 103 includes at least one of tantalum nitride and an insulating film. Therefore, in the connecting electrode 103 of this embodiment, it is unlikely that copper from the plug 106 will diffuse to the upper surface of the connecting electrode 103. Therefore, it is unlikely that clumps of copper oxide will form on the upper surface of the connecting electrode 103. Therefore, it is unlikely that the connection between the connecting electrode 103 and the wiring will be hindered by clumps of copper oxide. Furthermore, it is unlikely that the electrical resistance at the connection between the connecting electrode 103 and the wiring will increase due to clumps of copper oxide.

[0258] The shape of the photoelectric conversion film of the imaging device 1 of this embodiment will now be described. Figure 15 is a schematic cross-sectional view showing the photoelectric conversion film. Note that Figure 15 is an explanatory diagram, and some elements are omitted from the illustration.

[0259] In this embodiment, as shown in Figure 15, the angle θ formed between the side surface 107s and the bottom surface 107b of the photoelectric conversion film 107 in a cross-section parallel to the vertical direction is 70° or more and 90° or less. In this cross-section, at least a portion of the second electrode 120 or the second electrode 220 is located laterally than the side surface 107s. In the example shown in Figure 15, typically, after fabricating the photoelectric conversion film 107 with an angle θ of 70° or more and 90° or less, the counter electrode 108, etc., is formed in a film-like manner on the photoelectric conversion film 107. This improves the coverage of the film, such as the counter electrode 108, formed on the photoelectric conversion film 107. This is advantageous from the viewpoint of improving the adhesion between adjacent films, such as between the photoelectric conversion film 107 and the counter electrode 108, and improving how the electric field is applied to the photoelectric conversion film 107. Specifically, the angle θ can be 80° or more and 90° or less. In the example shown in Figure 15, specifically, in the cross-section, the entirety of the second electrode 120 or the second electrode 220 is located laterally than the side surface 107s. However, in this cross-section, only a portion of the second electrode 120 or the second electrode 220 may be located laterally than the side surface 107s.

[0260] Let me explain the above statement that at least a portion of the second electrode is located laterally than the side surface 107s of the photoelectric conversion film 107. This statement means that, with respect to the lateral direction perpendicular to the vertical direction, at least a portion of the second electrode is located on the opposite side from the internal region of the photoelectric conversion film 107 when viewed from the side surface 107s. The side surface 107s of the photoelectric conversion film 107 is the surface connecting the upper surface 107t and the lower surface 107b of the photoelectric conversion film 107.

[0261] In the example shown in Figure 15, specifically, the second electrode 120 or the second electrode 220 is the connecting electrode 103. The plug 130 is the plug 106.

[0262] The method for forming the photoelectric conversion film 107 is not limited to etching. For example, the photoelectric conversion film 107 can also be formed by depositing a film in a predetermined area using a mask. In this case, in a typical example, the angle θ is less than 1°.

[0263] (Fourth Embodiment) A camera system according to the fourth embodiment will now be described. Figure 16 is a schematic diagram of the camera system.

[0264] The camera system 604 shown in Figure 16 comprises an imaging device 600, an optical system 601, a camera signal processing unit 602, and a system controller 603. The imaging device 600 can be the imaging device 1 described in the first to third embodiments. The optical system 601 focuses light. The optical system 601 includes, for example, a lens. The camera signal processing unit 602 processes the data captured by the imaging device 600 and outputs it as an image or data. The system controller 603 controls the imaging device 600 and the camera signal processing unit 602. [Industrial applicability]

[0265] The technology disclosed herein can be used in digital still cameras and the like. [Explanation of symbols]

[0266] 1,600 imaging devices 10 pixel area 12 Vertical Drivers 13 Timing Generator 14 Signal Processing Circuits 15 Horizontal Driver 16 LVDS (Low Voltage Differential Signaling) device 17 Serial Conversion Unit 18 Counter electrode voltage supply unit 19 pads 100 pixels 101 circuit board 102 Insulating layer 102a,102b,102c,102d,102e,102f composition layer 102e1,107t,120a,220t top surface 103,104,120,153,154,220 electrode Layers 104a, 104ax, 104b, 104bx, 104px, 104qx, 104rx, 105a1, 105a2, 107x, 108x, 109x, 120t, 121, 122, 125, 126, 154a, 154b, 221, 222, 225a, 225b, 225c, 225ax, 225bx, 225cx, 229a, 229b, 229ax, 229bx Laminates 104x, 225x, 229x Plugs 105, 106, 130 First barrier film 105a First metal body 105b Photoelectric conversion film 107 Bottom surfaces 107b, 120b, 220b Side surfaces 107s, 120s, 220s Counter electrode 108<U+ Buffer layer 109 Sealing layer 110 Color filter 111 Planarization layer 112<U+ Microlens 113 Readout circuit 115 Storage diode 115d Top layer wiring 116 Connection surface 130m First hole 141 Mass of copper oxide 155 Photoresist 195 Electrode body 224 Insulating film 225 Contour 225m Molded bodies 228, 229 Optical system 601 Camera signal processing unit 602 System controller 603 Camera system 604

Claims

1. A photoelectric conversion film that converts light into electric charge, The electrode for collecting the aforementioned charge, The system comprises a plug having a connecting surface connected to the electrode and containing metal, The electrode is composed of multiple layers, The aforementioned plurality of layers include a first layer containing amorphous tantalum nitride, The uppermost of the aforementioned multiple layers contains titanium nitride, The uppermost layer is a second layer, separate from the first layer. Imaging device.

2. The first layer is thinner than the second layer. The imaging apparatus according to claim 1.

3. The lowest of the aforementioned multiple layers contains tantalum, The imaging apparatus according to claim 1 or claim 2.

4. A photoelectric conversion film that converts light into electric charge, The electrode for collecting the aforementioned charge, The device comprises a plug having a connecting surface connected to the electrode and containing metal, The electrode includes an electrode body and an insulating film. At least a portion of the upper surface of the electrode is formed by the electrode body, At least a portion of the lower surface of the electrode is formed by the electrode body, The insulating film comprises at least one material selected from silicon oxide, silicon nitride, alumina (ALO), and tetraethoxysilane (TEOS). Imaging device.

5. In a cross-section perpendicular to the thickness direction of the insulating film, the insulating film is surrounded by the electrode body. The imaging apparatus according to claim 4.

6. The electrode body includes a first layer disposed between the plug and the insulating film. The insulating film comprises an oxide, The preceding first layer contains a non-oxide, The imaging apparatus according to claim 4 or claim 5.

7. When viewed from above, at least a portion of the insulating film and at least a portion of the connection surface of the plug overlap. The imaging device according to any one of claims 4 to 6.

8. When viewed from above, the entire connection surface overlaps with the insulating film. The imaging apparatus according to claim 7.

9. The electrode body includes a second layer that constitutes the entire upper surface of the electrode. The imaging apparatus according to any one of claims 4 to 8.

10. The electrode body includes a first layer and a second layer, The insulating film is located between the first layer and the second layer. The imaging apparatus according to claim 4 or claim 5.

11. The thickness of the insulating film is 10 nm or more. The imaging apparatus according to any one of claims 4 to 10.

12. In a cross-section parallel to the thickness direction of the photoelectric conversion film, the angle formed between the side surface of the photoelectric conversion film and the lower surface of the photoelectric conversion film is 70° or more and 90° or less. In the cross-section, at least a portion of the electrode is located laterally than the side surface. The imaging apparatus according to any one of claims 1 to 11.

13. The plug contains copper, The imaging apparatus according to any one of claims 1 to 12.

14. A photoelectric conversion film that converts light into electric charge, The electrode for collecting the aforementioned charge, The device comprises a plug having a connecting surface connected to the electrode and containing metal, The electrode is composed of multiple layers, The aforementioned plurality of layers include a first layer containing amorphous tantalum nitride, The uppermost of the aforementioned multiple layers contains titanium nitride or tantalum nitride. Parts of the outer edges of each layer included in the aforementioned plurality of layers coincide. Imaging device.

15. A photoelectric conversion film that converts light into electric charge, The electrode for collecting the aforementioned charge, The device comprises a plug having a connecting surface connected to the electrode and containing metal, The electrode is composed of multiple layers, The aforementioned plurality of layers include a first layer containing amorphous tantalum nitride, The uppermost of the aforementioned multiple layers contains titanium nitride or tantalum nitride. All of the outer edges of each layer included in the aforementioned plurality of layers coincide. Imaging device.

16. A photoelectric conversion film that converts light into electric charge, The electrode for collecting the aforementioned charge, The device comprises a plug having a connecting surface connected to the electrode and containing metal, The electrode is composed of multiple layers, The aforementioned plurality of layers include a first layer containing amorphous tantalum nitride, The uppermost of the aforementioned multiple layers contains titanium nitride or tantalum nitride. Imaging device.

Images