Image sensor including control electrode, transparent electrode, and connection layer

Abstract

An image sensor according to one embodiment of the present disclosure is provided with: a plurality of pixel electrodes arranged side by side in a first direction; a control electrode; a photoelectric conversion film disposed on the plurality of pixel electrodes; a transparent electrode disposed on the photoelectric conversion film; an insulating layer disposed on at least a portion of an upper surface of the transparent electrode; and a connection layer electrically connecting the control electrode and the transparent electrode. The connection layer is in contact with at least one side surface of the transparent electrode, a side surface of the insulating layer, the at least one side surface of the transparent electrode, and a side surface of the photoelectric conversion film are aligned with each other, and a width of the connection layer in the first direction is larger than a width of the pixel electrode in the first direction.

Description

[0001] This application is a divisional application of the Chinese patent application with the application date of 2019 / 05 / 24, application number "201980025746.9", and invention name "Image sensor with control electrode, transparent electrode and connection layer". Technical Field

[0002] The present disclosure relates to an image sensor and a method for manufacturing the same. Background Art

[0003] An image sensor has a plurality of pixels arranged one-dimensionally or two-dimensionally, and the pixels include a light detection element that generates an electrical signal corresponding to the amount of incident light. A stacked image sensor is an image sensor that has a light detection element having a structure in which a pixel electrode, a photoelectric conversion film, and a transparent electrode are stacked in sequence from the substrate side as a pixel.

[0004] The light detection element of the stacked image sensor is connected to a signal detection circuit via a pixel electrode and is connected to a voltage control element via a transparent electrode. The signal detection circuit detects an electrical signal generated when light enters the light detection element.

[0005] The voltage control element controls the voltage of the transparent electrode so that the voltage is within a specified range in order to enable the signal detection circuit to correctly detect the electrical signal generated in the light detection element, or, when a current flows from the pixel electrode, causes a current of an equal amount to flow to the transparent electrode to prevent the light detection element from being charged.

[0006] Patent documents 1 and 2 disclose an image sensor including a photoelectric conversion film composed of an organic semiconductor, a transparent electrode formed on the organic photoelectric conversion film, a protective film formed on the transparent electrode, and wiring that electrically connects the transparent electrode exposed in an opening provided in the protective film to a voltage control element.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2014-60315

[0010] Patent Document 2: U.S. Patent No. 9224789 Summary of the invention

[0011] The present disclosure provides an image sensor capable of applying a voltage to a photoelectric conversion film with a low resistance via a transparent electrode with fewer manufacturing steps.

[0012] The exemplary image sensor disclosed in the present invention comprises: a plurality of pixel electrodes arranged in a first direction; a control electrode; a photoelectric conversion film arranged on the plurality of pixel electrodes; a transparent electrode arranged on the photoelectric conversion film; an insulating layer arranged on at least a portion of the upper surface of the transparent electrode; and a connecting layer electrically connecting the control electrode and the transparent electrode. The connecting layer contacts at least one side surface of the transparent electrode, the side surface of the insulating layer, the at least one side surface of the transparent electrode, and the side surface of the photoelectric conversion film are aligned with each other, and the width of the connecting layer in the first direction is greater than the width of the pixel electrode in the first direction.

[0013] According to the image sensor disclosed herein, a control electrode and a side surface of a transparent electrode are electrically connected by a connection layer, thereby being able to be manufactured with fewer manufacturing steps and to apply a voltage to a photoelectric conversion film with low resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram showing the circuit configuration of the imaging device.

[0015] Figure 2 It is a schematic diagram showing a cross section of a device structure of a unit pixel unit in an imaging device.

[0016] Figure 3A is a schematic cross-sectional view of the image sensor according to this embodiment.

[0017] Figure 3B This is a schematic top view of the image sensor of this embodiment with the protective film removed.

[0018] Figure 4A The diagram is a cross-sectional view showing steps in the method for manufacturing the image sensor according to the present embodiment.

[0019] Figure 4B The diagram is a cross-sectional view showing steps in the method for manufacturing the image sensor according to the present embodiment.

[0020] Figure 4C The diagram is a cross-sectional view showing steps in the method for manufacturing the image sensor according to the present embodiment.

[0021] Figure 4D The diagram is a cross-sectional view showing steps in the method for manufacturing the image sensor according to the present embodiment.

[0022] Figure 4E The diagram is a cross-sectional view showing steps in the method for manufacturing the image sensor according to the present embodiment.

[0023] Figure 4F The diagram is a cross-sectional view showing steps in the method for manufacturing the image sensor according to the present embodiment.

[0024] Figure 4G The diagram is a cross-sectional view showing steps in the method for manufacturing the image sensor according to the present embodiment.

[0025] Figure 4H The diagram is a cross-sectional view showing steps in the method for manufacturing the image sensor according to the present embodiment.

[0026] Figure 5 This is a schematic cross-sectional view showing a portion of another embodiment of an image sensor.

[0027] Figure 6 This is another form of the image sensor, and is a schematic top view of the state in which the protective film is removed.

[0028] Figure 7 This is another form of the image sensor, and is a schematic top view of the state in which the protective film is removed.

[0029] Figure 8 This is another form of the image sensor, and is a schematic top view of the state in which the protective film is removed.

[0030] Fig. 9A It is a schematic top view showing another form of an image sensor.

[0031] Fig. 9B Yes means Fig. 9A Schematic cross-sectional view of a portion of an image sensor.

[0032] Fig.10 The present invention is a cross-sectional view showing steps in another embodiment of a method for manufacturing an image sensor. DETAILED DESCRIPTION

[0033] In a stacked image sensor, the sensitivity of a photoelectric conversion film made of a certain material changes greatly depending on the voltage applied to the transparent electrode, and the sensitivity can be substantially set to 0. By utilizing this characteristic and changing the voltage of the transparent electrode, a stacked image sensor capable of electronic shutter operation can be realized.

[0034] In addition, other photoelectric conversion films can significantly change the spectral sensitivity characteristics of the photoelectric conversion film, i.e., the spectral spectrum, according to the voltage applied to the transparent electrode. By utilizing this characteristic, in a certain stacked image sensor, by changing the voltage of the transparent electrode, two or more different spectral sensitivity characteristics of the photoelectric conversion film can be changed.

[0035] In the case of these image sensors, the voltage control element realizes a function of an electronic shutter or a function of changing spectral sensitivity characteristics by temporally changing the voltage applied to the transparent electrode.

[0036] Thus, in the stacked image sensor, in order for the signal detection circuit to correctly detect the electrical signal generated in the light detection element, it is necessary to control the potential of the transparent electrode to be within a predetermined range through the voltage control element. In addition, when a current flows from the pixel electrode, in order to prevent the light detection element from being charged, the current must flow between the voltage control element and the transparent electrode.

[0037] To achieve these controls or operations, the lower the resistance of the voltage application path including the transparent electrode between the voltage control element and the photoelectric conversion film, the smaller the voltage fluctuation, the lower the power consumption, and the faster the time change.

[0038] On the other hand, among the materials used in the photoelectric conversion film, there are materials that react with oxygen, ozone, moisture, etc., thereby deteriorating the photoelectric conversion function. For example, in the case where the photoelectric conversion film is formed by an organic semiconductor, there are materials that easily react with oxygen, ozone, moisture, etc. among the organic semiconductors. Therefore, in the manufacturing process of the image sensor, the formation and composition of the photoelectric conversion film are preferably performed in an environment where the photoelectric conversion function does not deteriorate. For example, it is preferred to form the photoelectric conversion film and perform the composition in an inert atmosphere such as nitrogen or in a vacuum.

[0039] However, usually, in order to make the formation and patterning of the photoelectric conversion film all be carried out under an inert atmosphere or vacuum, a very large-scale manufacturing device is required. In addition, when the wafer having the photoelectric conversion film is transported between the manufacturing devices, in order to carry out under an inert atmosphere, a large-scale transporting device is also required.

[0040] The inventors of the present application have conceived an image sensor having a novel structure that connects a voltage control element and a photoelectric conversion film with low resistance and facilitates handling of the photoelectric conversion film in the manufacturing process. The image sensor and the method for manufacturing the image sensor disclosed in the present invention are summarized as follows.

[0041] [Project 1]

[0042] The image sensor of item 1 of the present disclosure comprises:

[0043] a plurality of pixel electrodes;

[0044] Control electrode;

[0045] A photoelectric conversion film disposed on the plurality of pixel electrodes;

[0046] A transparent electrode disposed on the photoelectric conversion film;

[0047] an insulating layer disposed on at least a portion of the upper surface of the transparent electrode; and

[0048] A connection layer electrically connects the control electrode and the transparent electrode.

[0049] The connection layer is in contact with at least one side surface of the transparent electrode.

[0050] In a cross section of the transparent electrode perpendicular to the upper surface, an end portion of the insulating layer is located on an inner side of the transparent electrode than an end portion of the transparent electrode.

[0051] Here, the transparent electrode may be formed of a conductive semiconductor. In addition, the control electrode may be formed of a metal or a metal compound.

[0052] [Project 2]

[0053] In the image sensor according to Item 1, the connection layer may be in contact with a side surface of the photoelectric conversion film.

[0054] [Item 3]

[0055] In the image sensor described in item 1 or 2, the connection layer may cover a part of the insulating layer.

[0056] [Item 4]

[0057] In the image sensor described in any one of items 1 to 3, the connection layer may be in contact with a portion of the upper surface of the transparent electrode.

[0058] [Item 5]

[0059] In the image sensor described in any one of items 1 to 4, the connection layer may overlap with a part of the plurality of pixel electrodes in a plan view.

[0060] [Item 6]

[0061] In the image sensor described in Item 5, the connection layer may have a light shielding property.

[0062] [Item 7]

[0063] The image sensor according to any one of items 1 to 6 may further include a protective film covering the connection layer and the insulating layer.

[0064] [Item 8]

[0065] In the image sensor described in any one of items 1 to 7, it may be that:

[0066] In a plan view, the transparent electrode has a polygonal shape.

[0067] The at least one side surface of the transparent electrode has a plurality of side surfaces.

[0068] The connection layer is in contact with the plurality of side surfaces of the transparent electrode.

[0069] [Item 9]

[0070] The image sensor of item 9 of the present disclosure comprises:

[0071] A plurality of pixel electrodes,

[0072] Control electrode,

[0073] The photoelectric conversion film is arranged on the plurality of pixel electrodes.

[0074] A transparent electrode is arranged on the above-mentioned photoelectric conversion film,

[0075] an insulating layer disposed on at least a portion of the upper surface of the transparent electrode,

[0076] A connection layer electrically connects the control electrode and the transparent electrode.

[0077] The connection layer is in contact with at least one side surface of the transparent electrode.

[0078] The insulating film does not include a hole for connecting the upper surface of the transparent electrode and the connection layer.

[0079] [Item 10]

[0080] The method for manufacturing an image sensor according to item 10 of the present disclosure comprises:

[0081] A step (A) of preparing a circuit unit having a plurality of pixel electrodes and a control electrode,

[0082] a step (B) of forming a photoelectric conversion film on the plurality of pixel electrodes,

[0083] a step (C) of forming a transparent electrode made of a conductive semiconductor on the upper surface of the photoelectric conversion film,

[0084] a step (D) of forming an insulating layer on the transparent electrode,

[0085] a step (E) of removing a portion of the photoelectric conversion film, a portion of the transparent electrode, and a portion of the insulating layer to perform patterning,

[0086] and forming a connection layer for electrically connecting the side surface of the transparent electrode exposed in the step (E) to the control electrode.

[0087] [Item 11]

[0088] In the method for manufacturing an image sensor according to item 10, it may be that:

[0089] In the step (F), the connection layer is also bonded to the photoelectric conversion film.

[0090] [Item 12]

[0091] In the method for manufacturing an image sensor according to item 10, it may be that:

[0092] In the above step (E),

[0093] removing a portion of the transparent electrode and a portion of the insulating layer by dry etching using a gas containing at least one of chlorine and fluorine,

[0094] A portion of the photoelectric conversion film is removed by dry etching using a gas containing oxygen.

[0095] [Item 13]

[0096] In the method for manufacturing an image sensor according to any one of items 10 to 12, the method may include:

[0097] In the step (E), the insulating layer is patterned so that the outer periphery of the upper surface of the transparent electrode is exposed.

[0098] In the step (F), the connection layer is also bonded to the outer peripheral portion of the transparent electrode.

[0099] [Item 14]

[0100] In the method for manufacturing an image sensor according to any one of items 10 to 12, the method may include:

[0101] In the step (F), the connection layer is also formed on at least a portion of the insulating layer.

[0102] Hereinafter, embodiments of the image sensor disclosed herein will be described with reference to the accompanying drawings.

[0103] (Overview of Imaging Device Including Image Sensor)

[0104] First, an image pickup device using the image sensor of the present disclosure will be generally described. Figure 1 The circuit configuration of the imaging device 500 is schematically shown. The imaging device 500 includes an image sensor 101 including a plurality of unit pixel cells 14 and peripheral circuits.

[0105] A plurality of unit pixel units 14 are arranged two-dimensionally on a semiconductor substrate, that is, in a row direction and a column direction, to form a pixel region. The image sensor 101 may also be a line sensor. In this case, the plurality of unit pixel units 14 may be arranged one-dimensionally. In the present application specification, the row direction and the column direction refer to the directions in which the rows and columns extend, respectively. That is, the vertical direction is the column direction, and the horizontal direction is the row direction.

[0106] Each unit pixel unit 14 includes a light detection unit 10, an amplifier transistor 11, a reset transistor 12, and an address transistor 13 as a row selection transistor. The light detection unit 10 includes a pixel electrode 50 and a transparent electrode 52. The image sensor 101 includes a voltage control element for applying a predetermined voltage to the transparent electrode 52. The voltage control element is, for example, a voltage control circuit, a voltage generating circuit such as a constant voltage source, a voltage reference line such as a ground line, etc. The voltage applied by the voltage control element is called a control voltage. In this embodiment, a voltage control circuit 60 is provided as a voltage control element. The voltage control circuit 60 can generate a certain control voltage or a plurality of control voltages with different values. For example, control voltages of more than two different values ​​can be generated, or a control voltage that continuously changes within a predetermined range can be generated. The voltage control circuit 60 determines the value of the generated control voltage according to the instructions of the operator who operates the camera device 500, the instructions of other control units provided by the camera device 500, etc., and generates a control voltage of the determined value. The voltage control circuit 60 is provided outside the photosensitive area as a part of the peripheral circuit. That is, the voltage control circuit 60 may be provided in the image sensor 101 .

[0107] For example, the voltage control circuit 60 generates two or more different control voltages and applies the control voltages to the transparent electrode 52, thereby changing the spectral sensitivity characteristics of the photoelectric conversion film 51. In addition, the change in the spectral sensitivity characteristics includes a spectral sensitivity characteristic in which the sensitivity of the photoelectric conversion film 51 becomes zero for the light to be detected. Thus, for example, in the imaging device 500, during the period in which the unit pixel unit 14 reads out the detection signal for each row, by applying the control voltage that makes the sensitivity of the photoelectric conversion film 51 zero from the voltage control circuit 60 to the transparent electrode 52, the influence of the incident light when reading out the detection signal can be made substantially zero. Thus, even if the detection signal is substantially read out for each row, a global shutter operation can be realized.

[0108] In this embodiment, if Figure 1As shown, by applying a control voltage to the transparent electrode 52 of the unit pixel unit 14 arranged in the row direction via the opposing electrode signal line 16, the voltage between the pixel electrode 50 and the transparent electrode 52 is changed, and the spectral sensitivity characteristics of the light detection unit 10 are switched. Alternatively, the electronic shutter action is realized by applying a control voltage to obtain a spectral sensitivity characteristic in which the sensitivity to light becomes zero at a specified timing during imaging. However, a control voltage may also be applied to the pixel electrode 50. In order to irradiate light to the light detection unit 10 and accumulate holes as signal charges in the pixel electrode 50, the pixel electrode is set to a relatively low potential relative to the transparent electrode 52. At this time, since the direction of electron movement is opposite, current flows from the pixel electrode 50 to the transparent electrode 52. In addition, in order to irradiate light to the light detection unit 10 and accumulate holes as signal charges in the pixel electrode 50, the pixel electrode is set to a relatively low potential relative to the transparent electrode 52. At this time, current flows from the transparent electrode 52 to the pixel electrode 50.

[0109] The pixel electrode 50 is connected to the gate electrode of the amplifier transistor 11, and the signal charges collected by the pixel electrode 50 are accumulated in the charge accumulation node 24 located between the pixel electrode 50 and the gate electrode of the amplifier transistor 11. In this embodiment, the signal charges are holes, but the signal charges may also be electrons.

[0110] The signal charge accumulated in the charge accumulation node 24 is applied to the gate electrode of the amplifier transistor 11 as a voltage corresponding to the amount of the signal charge. The amplifier transistor 11 constitutes a signal detection circuit and amplifies the voltage applied to the gate electrode. The address transistor 13 selectively reads the amplified voltage as a signal voltage. The source / drain electrodes of the reset transistor 12 are connected to the pixel electrode 50, and the reset transistor 12 resets the signal charge accumulated in the charge accumulation node 24. In other words, the reset transistor 12 resets the potential of the gate electrode of the amplifier transistor 11 and the pixel electrode 50.

[0111] In order to selectively perform the above-mentioned operation in a plurality of unit pixel units 14, the imaging device 500 includes a power supply wiring 21, a vertical signal line 17, an address signal line 26, and a reset signal line 27, which are respectively connected to the unit pixel units 14. Specifically, the power supply wiring 21 is connected to the source / drain electrodes of the amplifier transistor 11, and the vertical signal line 17 is connected to the source / drain electrodes of the address transistor 13. The address signal line 26 is connected to the gate electrode of the address transistor 13. In addition, the reset signal line 27 is connected to the gate electrode of the reset transistor 12.

[0112] The peripheral circuit includes a vertical scanning circuit 15, a horizontal signal readout circuit 20, a plurality of column signal processing circuits 19, a plurality of load circuits 18, and a plurality of differential amplifiers 22. The vertical scanning circuit 15 is also called a row scanning circuit. The horizontal signal readout circuit 20 is also called a column scanning circuit. The column signal processing circuit 19 is also called a row signal accumulation circuit. The differential amplifier 22 is also called a feedback amplifier.

[0113] The vertical scanning circuit 15 is connected to the address signal line 26 and the reset signal line 27, and selects the multiple unit pixel units 14 arranged in each row in units of rows to read the signal voltage and reset the potential of the pixel electrode 50. The power supply wiring 21 as a source follower power supply supplies a specified power supply voltage to each unit pixel unit 14. The horizontal signal readout circuit 20 is electrically connected to multiple column signal processing circuits 19. The column signal processing circuit 19 is electrically connected to the unit pixel unit 14 arranged in each column via the vertical signal line 17 corresponding to each column. The load circuit 18 is electrically connected to each vertical signal line 17. The load circuit 18 and the amplifier transistor 11 form a source follower circuit.

[0114] A plurality of differential amplifiers 22 are provided corresponding to each column. A negative input terminal of the differential amplifier 22 is connected to a corresponding vertical signal line 17. An output terminal of the differential amplifier 22 is connected to the unit pixel unit 14 via a feedback line 23 corresponding to each column.

[0115] The vertical scanning circuit 15 applies a row selection signal for controlling the on and off of the address transistor 13 to the gate electrode of the address transistor 13 via the address signal line 26. Thus, the row to be read is scanned and selected. The signal voltage is read from the unit pixel unit 14 of the selected row to the vertical signal line 17. In addition, the vertical scanning circuit 15 applies a reset signal for controlling the on and off of the reset transistor 12 to the gate electrode of the reset transistor 12 via the reset signal line 27. Thus, the row of the unit pixel unit 14 to be the object of the reset operation is selected. The vertical signal line 17 transmits the signal voltage read from the unit pixel unit 14 selected by the vertical scanning circuit 15 to the column signal processing circuit 19.

[0116] The column signal processing circuit 19 performs noise suppression signal processing represented by correlated double sampling, analog-to-digital conversion (AD conversion), and the like.

[0117] The horizontal signal readout circuit 20 sequentially reads out signals from the plurality of column signal processing circuits 19 to a horizontal common signal line (not shown).

[0118] The differential amplifier 22 is connected to the drain electrode of the reset transistor 12 via the feedback line 23. Therefore, when the address transistor 13 and the reset transistor 12 are in the on state, the differential amplifier 22 receives the output value of the address transistor 13 at the negative terminal. The differential amplifier 22 performs a feedback operation so that the gate potential of the amplifier transistor 11 becomes a predetermined feedback voltage. At this time, the output voltage value of the differential amplifier 22 is a positive voltage of 0V or near 0V. The feedback voltage means the output voltage of the differential amplifier 22.

[0119] Figure 2 The cross section of the device structure of the unit pixel unit 14 in the camera device 500 is schematically shown. The unit pixel unit 14 includes a semiconductor substrate 31, a charge detection circuit 25 and a light detection unit 10. The semiconductor substrate 31 is, for example, a p-type silicon substrate. The charge detection circuit 25 detects the signal charge captured by the pixel electrode 50 and outputs a signal voltage. The charge detection circuit 25 includes an amplifier transistor 11, a reset transistor 12 and an address transistor 13, and is formed on the semiconductor substrate 31.

[0120] The amplifier transistor 11 includes n-type impurity regions 41C and 41D formed in the semiconductor substrate 31 and functioning as a drain electrode and a source electrode, respectively, a gate insulating layer 38B located on the semiconductor substrate 31 , and a gate electrode 39B located on the gate insulating layer 38B.

[0121] The reset transistor 12 includes n-type impurity regions 41B and 41A formed in the semiconductor substrate 31 and functioning as a drain electrode and a source electrode, respectively, a gate insulating layer 38A located on the semiconductor substrate 31 , and a gate electrode 39A located on the gate insulating layer 38A.

[0122] The address transistor 13 includes n-type impurity regions 41D and 41E formed in the semiconductor substrate 31 and functioning as a drain electrode and a source electrode, respectively, a gate insulating layer 38C located on the semiconductor substrate 31, and a gate electrode 39C located on the gate insulating layer 38C. The n-type impurity region 41D is shared by the amplifier transistor 11 and the address transistor 13, whereby the amplifier transistor 11 and the address transistor 13 are connected in series.

[0123] In the semiconductor substrate 31, an element isolation region 42 is provided between adjacent unit pixel cells 14 and between the amplifier transistor 11 and the reset transistor 12. The element isolation region 42 electrically isolates the adjacent unit pixel cells 14. In addition, leakage of signal charges accumulated in the charge accumulation node is suppressed.

[0124] Interlayer insulating layers 43A, 43B, and 43C are stacked on the surface of the semiconductor substrate 31. In the interlayer insulating layer 43A, a contact plug 45A connected to the n-type impurity region 41B of the reset transistor 12, a contact plug 45B connected to the gate electrode 39B of the amplifier transistor 11, and a wiring 46A connecting the contact plug 45A and the contact plug 45B are buried. Thus, the n-type impurity region 41B (drain electrode) of the reset transistor 12 is electrically connected to the gate electrode 39B of the amplifier transistor 11. In addition, the wiring 46A is electrically connected to the pixel electrode 50 via the contact plug 47A, the wiring 46B, the contact plug 47B, the wiring 46C, and the contact plug 47C.

[0125] The light detection unit 10 is disposed on the interlayer insulating layer 43C. The light detection unit 10 includes a transparent electrode 52, a photoelectric conversion film 51, and a pixel electrode 50 on the semiconductor substrate 31 side relative to the transparent electrode 52. The photoelectric conversion film 51 is sandwiched between the transparent electrode 52 and the pixel electrode 50. In addition, the light detection unit 10 includes an insulating layer 119 formed on at least a portion of the upper surface of the transparent electrode 52. The light detection unit 10 may further include a protective film 120. The structure of the photoelectric conversion film 51 is described in detail below. The pixel electrode 50 is disposed on the interlayer insulating layer 43C.

[0126] The transparent electrode 52 is made of a semiconductor that is transparent to the light to be detected and has conductivity. For example, the transparent electrode 52 is made of indium tin oxide (ITO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), etc. Other transparent conductive semiconductors can also be used. The pixel electrode 50 is formed of a metal such as aluminum and copper, polysilicon doped with impurities to give conductivity, etc.

[0127] like Figure 2 As shown, the unit pixel unit 14 has a color filter 53 on the transparent electrode 52 of the light detection unit 10. A micro lens 54 may be further provided on the color filter 53.

[0128] In the present embodiment, the photoelectric conversion film 51 and the transparent electrode 52 of each unit pixel unit 14 are respectively connected to the photoelectric conversion film 51 and the transparent electrode 52 of the adjacent unit pixel unit 14, forming an integrated photoelectric conversion film 51 and transparent electrode 52. However, the photoelectric conversion film 51 may also be separated for each unit pixel unit 14. In addition, the transparent electrode 52 may also be integrally connected to each row or column of the two-dimensionally configured unit pixel unit 14. In contrast, the pixel electrode 50 of each unit pixel unit 14 is not connected to the pixel electrode 50 of the adjacent unit pixel unit 14, and is independent.

[0129] In addition, the image sensor 101 may detect the capacitance change of the photoelectric conversion film instead of the charge based on the photoelectric conversion. Such a type of image sensor and camera device is disclosed in, for example, International Publication No. WO2017 / 081847. That is, the photoelectric conversion film 51 may generate hole-electron pairs corresponding to the intensity of the incident light, or the capacitance may change according to the intensity of the incident light. By detecting the change in the generated charge or capacitance, the light incident on the photoelectric conversion film 51 can be detected.

[0130] (Structure of image sensor)

[0131] Figure 3A is a schematic cross-sectional view of the image sensor 101, Figure 3B 1 is a schematic top view of the image sensor 101 with the protective film 120 removed. Figure 2 The semiconductor substrate 31 and the interlayer insulating layers 43A, 43B, and 43C are collectively shown as a substrate 100 .

[0132] The image sensor 101 includes the above-mentioned plurality of pixel electrodes 50, the photoelectric conversion film 51, and the transparent electrode 52. In addition, the image sensor 101 further includes a control electrode 112 and a connection portion 115. The plurality of pixel electrodes 50 and the control electrode 112 constitute a circuit portion formed on the substrate 100. In addition, the connection portion 115 constitutes a part of the counter electrode signal line 16.

[0133] The plurality of pixel electrodes 50 are arranged one-dimensionally or two-dimensionally and embedded in the substrate 100, so that the upper surfaces of the plurality of pixel electrodes 50 are exposed from the upper surface 100a of the substrate 100. A photoelectric conversion film 51 is arranged on the upper surface 100a of the substrate 100 in a manner covering the plurality of pixel electrodes 50, and a transparent electrode 52 is arranged on the photoelectric conversion film 51. The transparent electrode 52 covers the upper surface 51a of the photoelectric conversion film 51 in a manner covering at least the region of the photoelectric conversion film 51 where the pixel electrodes 50 are provided. In the present embodiment, the transparent electrode 52 is formed to cover the entire upper surface 51a of the photoelectric conversion film 51.

[0134] The insulating layer 119 is formed to cover at least a portion of the upper surface 52a of the transparent electrode 52. The insulating layer 119 may cover the upper surface 52a so as to cover at least the region of the transparent electrode 52 where the pixel electrode 50 is provided.

[0135] The connection portion 115 is joined to the control electrode 112 and the transparent electrode 52 to electrically connect them. Specifically, the connection portion 115 is joined to the control electrode 112 exposed at the substrate 100 and the side 52s of the transparent electrode 52. The connection portion 115 also covers the side 51s of the photoelectric conversion film 51. In addition, the connection portion 115 covers a portion of the upper surface 119a of the insulating layer 119 other than the area above the pixel electrode 50. The joining area between the connection portion 115 and the control electrode 112 may be larger or smaller than the joining area between the connection portion 115 and the transparent electrode 52, or may be the same.

[0136] In the present embodiment, the photoelectric conversion film 51, the insulating layer 119, and the transparent electrode 52 have a rectangular shape in a plan view, and the control electrode 112 is arranged close to the sides 52e and 52f among the four sides 52c, 52d, 52e, and 52f of the transparent electrode 52. Therefore, the image sensor 101 includes two connecting portions 115, and the two connecting portions 115 are respectively bonded to the control electrode 112 and the side surface 52s of the transparent electrode 52 at positions close to the sides 52e and 52f of the transparent electrode 52, thereby electrically connecting the control electrode 112 and the transparent electrode 52. In the present embodiment, at each of the four sides 52c, 52d, 52e, and 52f of the transparent electrode 52, the side surface 119s of the insulating layer 119 is located on the same plane as the side surface 52s of the transparent electrode 52.

[0137] The protection film 120 is provided on the upper surface 100 a of the substrate 100 so as to cover the connection portion 115 and the insulating layer 119 .

[0138] The photoelectric conversion film 51 is composed of, for example, an organic semiconductor. The photoelectric conversion film 51 may include one or more organic semiconductor layers. For example, the photoelectric conversion film 51 may include, in addition to a photoelectric conversion layer that generates hole-electron pairs, a carrier transport layer that transports electrons or holes, a blocking layer that blocks carriers, and the like. These organic semiconductor layers may be organic p-type semiconductors and organic n-type semiconductors of known materials.

[0139] The transparent electrode 52 is formed of the above-mentioned materials. The control electrode 112 is composed of a metal or a metal compound and has light shielding properties. For example, the control electrode 112 is formed of titanium, titanium nitride, aluminum, silicon, aluminum containing copper, copper, tungsten, etc., or alloys thereof. The control electrode 112 may be composed of a single layer of the above-mentioned materials, or may have a stacked structure containing multiple layers.

[0140] The connection portion 115 is made of a metal or a metal compound. For example, the connection portion 115 is made of titanium, titanium nitride, aluminum, silicon, aluminum containing copper (AlSiCu), copper, tungsten, gold, silver, nickel, cobalt, etc., or an alloy thereof. In addition, like the control electrode 112, it can be a single layer or a stacked layer.

[0141] The insulating layer 119 and the protective film 120 are made of insulating materials. For example, the insulating layer 119 is made of silicon oxide, silicon nitride, silicon oxynitride, organic or inorganic polymer materials, etc. The insulating layer 119 and the protective film 120 may be transparent to light of a wavelength to be detected by the image sensor 101.

[0142] (Manufacturing method of image sensor)

[0143] The image sensor 101 can be manufactured by, for example, the following method.

[0144] (A) Process of preparing the circuit part

[0145] First, if Figure 4A As shown, a circuit unit is prepared. Specifically, as described above, a substrate 100 is prepared in which a plurality of pixel electrodes 50 and a control electrode 112 are exposed on an upper surface 100a. More specifically, the circuit unit includes a Figure 2 The structure shown can be manufactured using a known method for manufacturing a semiconductor device.

[0146] (B) Step of forming a photoelectric conversion film

[0147] like Figure 4B As shown, a photoelectric conversion film 51 is formed on the upper surface 100a of the substrate 100 to cover at least the pixel electrode 50. The photoelectric conversion film 51 can be formed by spin coating, spraying, die coating, spray coating, vacuum evaporation, screen printing, or the like.

[0148] (C) Step of forming a transparent electrode

[0149] like Figure 4B As shown, the transparent electrode 52 is formed on the photoelectric conversion film 51. The transparent electrode 52 is formed on at least the region of the photoelectric conversion film 51 where the pixel electrode 50 is provided. The transparent electrode 52 can be formed by a sputtering method.

[0150] (D) Step of forming an insulating layer

[0151] like Figure 4BAs shown, an insulating layer 119 is formed on the transparent electrode 52. The insulating layer 119 is formed on at least the region of the transparent electrode 52 where the pixel electrode 50 is provided. The insulating layer 119 can be formed by atomic layer deposition (ALD), chemical vapor deposition (CVD), sputtering, or the like.

[0152] (E) Patterning process

[0153] The photoelectric conversion film 51, the transparent electrode 52, and the insulating layer 119 are patterned by removing a portion of the photoelectric conversion film 51, a portion of the transparent electrode 52, and a portion of the insulating layer 119, respectively. Figure 4C As shown in FIG. 1 , a photosensitive resist 400 is formed on the insulating layer 119. For example, the resist 400 is formed by spin coating. Next, the resist 400 is exposed to light using a photomask and developed, thereby forming a Figure 4D As shown, a mask of a resist 400 having a prescribed pattern is formed.

[0154] Next, the photoelectric conversion film 51, the transparent electrode 52, and the insulating layer 119 are etched using the mask of the resist 400. The photoelectric conversion film 51, the transparent electrode 52, and the insulating layer 119 may be patterned by dry etching.

[0155] The insulating layer 119 and the transparent electrode 52 may use a gas containing halogens such as fluorine, chlorine, bromine and iodine, or may use a gas containing at least one of fluorine and chlorine. In addition, dry etching may use reactive etching (RIE) in which a gas is plasmatized by plasma discharge and chemical species of the plasmatized gas react with the insulating layer 119 and the transparent electrode 52. Typically, the insulating layer 119 and the transparent electrode 52 are made of a material containing nitrogen or silicon, so by using these gases and etching methods, the insulating layer 119 and the transparent electrode 52 can be efficiently etched.

[0156] On the other hand, the photoelectric conversion film 51 can also be dry-etched by a gas containing oxygen. More specifically, the reaction chamber is filled with a gas containing oxygen, and the photoelectric conversion film 51 is oxidized by chemical etching based on an oxidation reaction. Since the photoelectric conversion film 51 contains a large amount of carbon, it can be removed as carbon oxides by an oxidation reaction with oxygen.

[0157] In this way, by etching the insulating layer 119, the transparent electrode 52, and the photoelectric conversion film 51 using different gas species, damage caused by plasma during dry etching can be suppressed, and side etching can be controlled. In addition, since the upper surface 51a of the photoelectric conversion film 51 is covered by the insulating layer 119, only the side surface 51s is exposed to the outside during the manufacturing process of the image sensor 101. As a result, during etching and other manufacturing processes, the photoelectric conversion film 51 can be suppressed from contacting with oxygen, ozone, moisture, etc. and deteriorating.

[0158] Through the composition process, such as Figure 4E As shown, a portion of the photoelectric conversion film 51, a portion of the transparent electrode 52, and a portion of the insulating layer 119 are removed respectively, and the photoelectric conversion film 51, the transparent electrode 52, and the insulating layer 119 having a desired pattern and with the side 51s, the side 52s, and the side 119s exposed can be formed. When the amount of side etching is small, the side 119s of the insulating layer 119 and the side 52s of the transparent electrode 52 are substantially located on the same plane.

[0159] (F) Step of forming a connection layer

[0160] A connection portion 115 is formed to electrically connect the side surface 52s of the transparent electrode 52 to the control electrode 112. Figure 4F As shown in FIG. 1 , the upper surface 119a of the insulating layer 119, the side surface 119s of the insulating layer 119, the side surface 52s of the transparent electrode 52, and the side surface 51s of the photoelectric conversion film 51 are covered to form a layer 115B of a metal or a metal compound on the entire upper surface 100a of the substrate 100. The layer 115B can be formed by a sputtering method, a vacuum evaporation method, or the like. Then, a resist (not shown) is formed to expose at least the region where the pixel electrode 50 is provided, and the layer 115B is etched using the resist as a mask, thereby forming a Figure 4G As shown, a connection portion 115 is formed on the upper surface 100 a of the substrate 100 , which is connected to the control electrode 112 and to the side surface 52 s of the transparent electrode 52 .

[0161] (G) Step of forming a protective film

[0162] When the image sensor 101 is provided with the protective film 120, Figure 4H As shown, a protective film is formed on the upper surface 100a of the substrate 100 to cover the connection portion 115 and the insulating layer 119. In this way, the image sensor 101 is manufactured.

[0163] (Characteristics of image sensors)

[0164] According to the image sensor 101, in the voltage application path from the control electrode 112 to the photoelectric conversion film 51, the portion that does not require light transmittance is wired with a connection portion 115 having a higher conductivity than the transparent electrode 52 instead of the transparent electrode 52. Therefore, the voltage of the control electrode 112 can be applied to the photoelectric conversion film 51 via the transparent electrode 52 with a low resistance, thereby suppressing the voltage fluctuation in the photoelectric conversion film 51. Thus, an image sensor capable of more stable imaging is realized. In addition, an imaging device used in a mobile device that pursues lower power consumption can realize a high-speed electronic shutter or an imaging device capable of switching the spectral sensitivity characteristics at a higher speed.

[0165] In addition, by using the above-mentioned manufacturing process, the photoelectric conversion film 51 is covered with an insulating layer, and damage to the photoelectric conversion film 51 in the manufacturing process of the image sensor can be suppressed. The contact between the transparent electrode 52 and the connecting portion 115 is performed at the side 52s of the transparent electrode 52, so the side 52s connected to the connecting portion 115 is formed by the composition of the transparent electrode 52, and there is no need to form an opening for achieving contact in the insulating layer 119 as in the image sensors disclosed in Patent Documents 1 and 2. Therefore, the number of masks and the number of manufacturing processes in the manufacturing process of the image sensor 101 can be reduced, and the manufacturing cost of the image sensor 101 can be reduced, and the manufacturing time can be shortened. Therefore, according to this embodiment, a high-performance image sensor 101 can be manufactured at a low cost.

[0166] (Other forms)

[0167] The image sensor 101 of this embodiment can be modified in various ways.

[0168] The configuration and shape of the connecting portion 115 can be changed in various ways. Figure 5 As shown, the portion 115A of the connection portion 115 that covers the upper surface 119a of the insulating layer 119 can overlap with at least a portion of the plurality of pixel electrodes 50 in a plan view. For the unit pixel unit 14 of the pixel electrode 50 that overlaps with the portion 115A of the connection portion 115, the connection portion 115 functions as a light shielding film, and light is never incident. Therefore, the unit pixel unit 14 can be used to obtain a reference signal in a dark state, that is, optical black.

[0169] like Figure 6As shown, the connection portion 115 can be arranged on three sides of the rectangular shape of the transparent electrode 52. In this case, the connection portion 115 is bonded to the three side surfaces 52s of the sides 52c, 52d, and 52f. In this form, one control electrode 112 is arranged on the upper surface 100a of the substrate 100. According to this form, the control electrode 112 is arranged only in one place, but the low-resistance connection portion 115 is connected to the three sides of the transparent electrode 52, and the bonding area between the connection portion 115 and the transparent electrode 52 becomes larger, and the connection portion 115 can be electrically connected to the transparent electrode 52 with a lower resistance. Therefore, the delay when applying a voltage to the transparent electrode 52 is suppressed, and the synchronization of the voltage change is improved.

[0170] like Figure 7 , Figure 8 As shown, the connection portion 115 can be arranged on the four sides of the rectangular shape of the transparent electrode 52. In this case, the connection portion 115 is connected to the four side surfaces 52s of the sides 52c, 52d, 52e, and 52f. Figure 7 As shown, the gap 300 can be provided at the connecting portion 115, as shown in FIG. Figure 8 As shown, the gap 300 may not be provided. Figure 7 When the gap 300 is provided as shown in FIG. 1 , the gap 300 is used, for example, to hold a mask of an opening of the light irradiation region when the connection portion 115 is formed using a shadow mask. Figure 8 As shown, when the connecting portion 115 continuously connects the side surfaces 52s of the four sides of the rectangular shape, the delay when the voltage is applied to the transparent electrode 52 is further suppressed, and the synchronization of the voltage change is improved. In addition, since the connecting portion 115 covers all the sides of the transparent electrode 52 and the photoelectric conversion film 51, it has both the function of preventing the photoelectric conversion film 51 from being peeled off from the substrate and the function of preventing the side surfaces of the photoelectric conversion film 51 from being exposed to the atmosphere.

[0171] like Fig. 9A as well as Fig. 9B As shown in FIG. 1 , a portion of the upper surface 52a of the transparent electrode 52 may not be covered by the insulating layer 119. Specifically, the outer peripheral portion 52ap of the upper surface 52a may not be covered by the insulating layer 119 but may be exposed from the insulating layer 119. Such a structure may be, for example, Fig.10As shown, in the patterning process (E), when the insulating layer 119, the transparent electrode 52, and the photoelectric conversion film 51 are formed by etching using the resist 400, the insulating layer 119 can also be formed by etching in the direction perpendicular to the thickness direction. In the patterning process (E), the insulating layer 119 is exposed to the etching environment for the longest time, so the insulating layer 119 is etched to the maximum extent in the direction perpendicular to the thickness direction, and the side surface 119s is retreated, so that the outer periphery 52ap of the transparent electrode 52 is exposed. In this case, at each of the four sides 52c, 52d, 52e, and 52f of the transparent electrode 52, the side surface 119s of the insulating layer 119 is located closer to the center of the transparent electrode 52 than the side surface 52s of the transparent electrode 52. Fig. 9B In the cross-sectional view shown, the end of the insulating layer 119 is located on the inner side of the transparent electrode 52 than the end of the transparent electrode 52 .

[0172] The peripheral portion 52ap of the upper surface 52a of the transparent electrode 52 that is not covered by the insulating layer 119 may be covered and joined by the connecting portion 115. In this case, the connecting portion may also cover the protective film 120, or may cover the peripheral portion 52ap of the transparent electrode 52 but not be covered by the protective film 120. By joining the peripheral portion 52ap to the connecting portion 115, the contact area between the transparent electrode 52 and the connecting portion 115 can be made larger, and the transparent electrode 52 and the connecting portion 115 can be electrically connected with lower resistance.

[0173] The image sensor disclosed herein can be used in imaging devices for various purposes.

[0174] Marking Description

[0175] 10 Light detection unit

[0176] 11 Amplifier transistor

[0177] 12 Reset transistor

[0178] 13 Address transistor

[0179] 14 Unit pixel unit

[0180] 15 Vertical scanning circuit

[0181] 16 Counter electrode signal line

[0182] 17 Vertical signal line

[0183] 18 Load Circuit

[0184] 19 columns signal processing circuit

[0185] 20 Horizontal signal readout circuit

[0186] 21 Power Wiring

[0187] 22 Differential Amplifier

[0188] 23 Feedback line

[0189] 24 Charge storage nodes

[0190] 25 Charge detection circuit

[0191] 26 Address signal lines

[0192] 27 Reset signal line

[0193] 30 Voltage Control Circuit

[0194] 31 Semiconductor substrate

[0195] 38A, 38B, 38C gate insulation layer

[0196] 39A, 39B, 39C gate electrodes

[0197] 41B, 41C, 41D n-type impurity regions

[0198] 42 Component separation area

[0199] 43A, 43B, 43C interlayer insulation layer

[0200] 45A, 45B, 47A, 47B, 47C contact plugs

[0201] 46A, 46B, 46C wiring

[0202] 50 pixel electrode

[0203] 51 Photoelectric conversion film

[0204] 51a Upper surface

[0205] 51s side view

[0206] 52 Transparent Electrode

[0207] 52a Upper surface

[0208] 52ap peripheral

[0209] 52c, 52d, 52e, 52f edges

[0210] 52s side view

[0211] 53 Color Filters

[0212] 60 Voltage Control Circuit

[0213] 100 substrates

[0214] 100a upper surface

[0215] 101 Image Sensor

[0216] 112 control electrode

[0217] 115 connection

[0218] Section 115A

[0219] 115B Floor

[0220] 119 insulation layer

[0221] 119a Upper surface

[0222] 119s side

[0223] 120 protective film

[0224] 300 Clearance

[0225] 400 resist

[0226] 500 camera device.

Claims

1. An image sensor, characterized in that: have: A plurality of pixel electrodes are arranged in a first direction; Control electrode; A photoelectric conversion film is disposed on the plurality of pixel electrodes; A transparent electrode is disposed on the photoelectric conversion film; An insulating layer disposed on at least a portion of the upper surface of the transparent electrode; as well as A connecting layer electrically connecting the control electrode and the transparent electrode; The connecting layer is in contact with at least one side surface of the transparent electrode; The side surface of the insulating layer, the at least one side surface of the transparent electrode, and the side surface of the photoelectric conversion film are aligned with each other; A width of the connection layer in the first direction is greater than a width of the pixel electrode in the first direction.

2. The image sensor according to claim 1, wherein: The connection layer is also in contact with a side surface of the photoelectric conversion film.

3. The image sensor according to claim 1 or 2, characterized in that: The connection layer covers a portion of the insulating layer.

4. The image sensor according to claim 1 or 2, characterized in that: The connection layer does not contact the upper surface of the transparent electrode.

5. The image sensor according to claim 1 or 2, characterized in that: The connection layer overlaps a portion of the plurality of pixel electrodes in a plan view.

6. The image sensor according to claim 1 or 2, characterized in that: The connection layer has a light-shielding property.

7. The image sensor according to claim 1 or 2, characterized in that: A protective film covering the connection layer and the insulating layer is further provided.

8. The image sensor according to claim 1 or 2, characterized in that: In a plan view, the transparent electrode has a polygonal shape; The at least one side surface of the transparent electrode has a plurality of side surfaces; The connection layer is in contact with the plurality of side surfaces of the transparent electrode.

9. The image sensor according to claim 1 or 2, characterized in that: The insulating layer does not include a hole for connecting the upper surface of the transparent electrode and the connection layer.

10. The image sensor according to claim 1 or 2, characterized in that: In a plan view, the connection layer overlaps at least a portion of the insulating layer, at least a portion of the transparent electrode, and at least a portion of the photoelectric conversion film.

11. A method for manufacturing an image sensor, characterized in that: The following processes are available: Preparing a substrate having a plurality of pixel electrodes and a control electrode, wherein the plurality of pixel electrodes are arranged in a first direction; forming a photoelectric conversion film on the plurality of pixel electrodes; forming a transparent electrode on the upper surface of the photoelectric conversion film; forming an insulating layer on the transparent electrode; The photoelectric conversion film, the transparent electrode and the insulating layer are patterned so that the side surface of the insulating layer, the side surface of the transparent electrode and the side surface of the photoelectric conversion film are aligned; as well as forming a connection layer for electrically connecting the side surface of the transparent electrode exposed by the patterning to the control electrode; A width of the connection layer in the first direction is greater than a width of the pixel electrode in the first direction.

12. The method for manufacturing an image sensor according to claim 11, wherein: In the patterning step, a hole for connecting the upper surface of the transparent electrode and the connection layer is not formed in the insulating layer.

13. The method for manufacturing an image sensor according to claim 11 or 12, characterized in that: In the step of forming the connection layer, the connection layer is brought into contact with the photoelectric conversion film.

14. The method for manufacturing an image sensor according to claim 11 or 12, characterized in that: In the patterning step, the insulating layer is patterned so that the outer periphery of the upper surface of the transparent electrode is exposed. In the step of forming the connection layer, the connection layer is brought into contact with the outer peripheral portion of the transparent electrode.

15. The method for manufacturing an image sensor according to claim 11 or 12, characterized in that: In the step of forming the connection layer, the connection layer is also formed on at least a portion of the insulating layer.

Images