Imaging device

Abstract

To provide an imaging device capable of further suppressing noise in a pixel signal.SOLUTION: An imaging device according to one embodiment of the present disclosure includes: a semiconductor substrate that includes a photoelectric conversion portion configured to photoelectrically convert incident light, a charge holding portion configured to accumulate charge photoelectrically converted by the photoelectric conversion portion, and a reading circuit configured to read the charge; a first light-shielding layer provided on one main surface of the semiconductor substrate; a contact that penetrates the first light-shielding layer and extends in a direction normal to the one main surface of the semiconductor substrate; and a contact wiring layer that electrically connects the contact and a source or a drain of a field effect transistor provided on the semiconductor substrate. The one main surface of the semiconductor substrate includes a charge accumulation region that includes at least the photoelectric conversion portion and the charge holding portion, and a non-charge accumulation region that includes the reading circuit. The contact wiring layer extends to the non-charge accumulation region, and is electrically connected to the contact in the non-charge accumulation region.SELECTED DRAWING: Figure 11

Description

[Technical field]

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

[0002] In recent years, the sensitivity of image pickup devices has been increasing, which has resulted in an increase in the influence of crosstalk between adjacent pixels caused by reflection of light inside the image pickup device.

[0003] In view of this, it has been proposed to provide a light-shielding film inside the imaging device to suppress stray light inside the imaging device (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-216970 A Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, in an imaging device, it is desirable to more effectively block reflected light generated within the device so that electric charges not due to light from a subject are not generated due to the light reflected within the device.

[0006] Therefore, it is desirable to provide an imaging device that can further suppress noise in pixel signals. [Means for solving the problem]

[0007] An imaging device according to one embodiment of the present disclosure includes a semiconductor substrate having a photoelectric conversion unit that photoelectrically converts incident light, a charge retention unit that accumulates charge photoelectrically converted by the photoelectric conversion unit, and a readout circuit that reads out the charge, a first light-shielding film provided on one main surface of the semiconductor substrate, a contact extending through the first light-shielding film in a normal direction to the one main surface of the semiconductor substrate, and a contact wiring layer that electrically connects the contact to a source or drain of a field effect transistor provided on the semiconductor substrate, wherein the one main surface of the semiconductor substrate is composed of a charge accumulation region including at least the photoelectric conversion unit and the charge retention unit, and a non-charge accumulation region including the readout circuit, and the contact wiring layer extends to the non-charge accumulation region and is electrically connected to the contact in the non-charge accumulation region.

[0008] In the imaging device according to an embodiment of the present disclosure, it is possible to more efficiently block the incidence of reflected light on the photoelectric conversion unit, the charge storage unit, etc. As a result, for example, in the imaging device according to an embodiment of the present disclosure, it is possible to suppress the generation of new charges due to the reflected light inside the imaging device. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic explanatory diagram illustrating an overall configuration of an imaging device to which the technology according to the present disclosure is applied. [Diagram 2] 1 is a longitudinal sectional view showing a configuration of a pixel in an imaging device according to a first embodiment of the present disclosure. [Diagram 3] 4 is a vertical cross-sectional view showing a first configuration example of the extension part according to the embodiment. FIG. [Figure 4A] 5A to 5C are vertical cross-sectional views illustrating one step of a method for forming an overhanging portion according to the first configuration example. [Figure 4B] 5A to 5C are vertical cross-sectional views illustrating one step of a method for forming an overhanging portion according to the first configuration example. [Figure 4C] 5A to 5C are vertical cross-sectional views illustrating one step of a method for forming an overhanging portion according to the first configuration example. [Figure 4D] 5A to 5C are vertical cross-sectional views illustrating one step of a method for forming an overhanging portion according to the first configuration example. [Diagram 5]FIG. 11 is a vertical cross-sectional view showing a second configuration example of the extension part according to the embodiment. [Figure 6A] 10 is a vertical cross-sectional view illustrating one step of a method for forming an overhang portion according to a second configuration example. FIG. [Figure 6B] 10 is a vertical cross-sectional view illustrating one step of a method for forming an overhang portion according to a second configuration example. FIG. [Figure 6C] 10 is a vertical cross-sectional view illustrating one step of a method for forming an overhang portion according to a second configuration example. FIG. [Figure 6D] 10 is a vertical cross-sectional view illustrating one step of a method for forming an overhang portion according to a second configuration example. FIG. [Figure 6E] 10 is a vertical cross-sectional view illustrating one step of a method for forming an overhang portion according to a second configuration example. FIG. [Figure 7] 1 is a vertical cross-sectional view showing an example of an imaging device to which the technology according to the embodiment can be applied. [Figure 8] 1 is a vertical cross-sectional view showing an example of an imaging device to which the technology according to the embodiment can be applied. [Figure 9] 1 is a vertical cross-sectional view showing an example of an imaging device to which the technology according to the embodiment can be applied. [Figure 10] 1 is a vertical cross-sectional view showing an example of an imaging device to which the technology according to the embodiment can be applied. [Figure 11] 11 is a plan view showing an example of a pixel of an imaging device according to a second embodiment of the present disclosure. FIG. [Figure 12] 12 is a vertical cross-sectional view showing a cross-sectional structure taken along line C-CC in FIG. 11. [Figure 13] 13 is a vertical cross-sectional view showing a modification of the cross-sectional structure shown in FIG. 12. [Figure 14A] 1 is a vertical cross-sectional view illustrating a step of a first method for forming a contact wiring layer. FIG. [Figure 14B] 1 is a vertical cross-sectional view illustrating a step of a first method for forming a contact wiring layer. FIG. [Figure 14C] 1 is a vertical cross-sectional view illustrating a step of a first method for forming a contact wiring layer. FIG. [Figure 14D] 1 is a vertical cross-sectional view illustrating a step of a first method for forming a contact wiring layer. FIG. [Figure 14E]1 is a vertical cross-sectional view illustrating a step of a first method for forming a contact wiring layer. FIG. [Figure 14F] 1 is a vertical cross-sectional view illustrating a step of a first method for forming a contact wiring layer. FIG. [Figure 14G] 1 is a vertical cross-sectional view illustrating a step of a first method for forming a contact wiring layer. FIG. [Figure 14H] 1 is a vertical cross-sectional view illustrating a step of a first method for forming a contact wiring layer. FIG. [Figure 15A] 10 is a vertical cross-sectional view illustrating a step of a second method for forming a contact wiring layer. FIG. [Figure 15B] 10 is a vertical cross-sectional view illustrating a step of a second method for forming a contact wiring layer. FIG. [Figure 15C] 10 is a vertical cross-sectional view illustrating a step of a second method for forming a contact wiring layer. FIG. [Figure 15D] 10 is a vertical cross-sectional view illustrating a step of a second method for forming a contact wiring layer. FIG. [Figure 15E] 10 is a vertical cross-sectional view illustrating a step of a second method for forming a contact wiring layer. FIG. [Figure 15F] 10 is a vertical cross-sectional view illustrating a step of a second method for forming a contact wiring layer. FIG. [Figure 16] 1 is a vertical cross-sectional view showing an example of an imaging device to which the technology according to the embodiment can be applied. [Figure 17] 1 is a vertical cross-sectional view showing an example of an imaging device to which the technology according to the embodiment can be applied. [Figure 18] 1 is a vertical cross-sectional view showing an example of an imaging device to which the technology according to the embodiment can be applied. [Figure 19] 1 is a block diagram showing an example of a schematic configuration of an imaging system including an imaging device according to a first or second embodiment of the present disclosure. [Figure 20] 20 illustrates an example of a flowchart of an imaging operation in the imaging system illustrated in FIG. 19. [Figure 21] 1 is a block diagram showing an example of a schematic configuration of a vehicle control system; [Figure 22] 4 is an explanatory diagram showing an example of the installation positions of an outside-vehicle information detection unit and an imaging unit; FIG. [Diagram 23] 1 is a diagram illustrating an example of a schematic configuration of an endoscopic surgery system. [Figure 24] 2 is a block diagram showing an example of a functional configuration of a camera head and a CCU. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. The embodiment described below is a specific example of the present disclosure, and the technology according to the present disclosure is not limited to the following aspects. Furthermore, the arrangement, dimensions, and dimensional ratios of each component shown in each drawing of the present disclosure are not limited to those shown in each drawing.

[0011] The explanation will be given in the following order. 1. Overall configuration of the imaging device 2. First embodiment 2.1.Pixel Structure 2.2.Example of the extension configuration 2.3. Variations 3. Second embodiment 3.1.Pixel Structure 3.2.Example of contact wiring layer configuration 3.3. Method for forming contact wiring layer 3.4. Modifications 4. Application Examples

[0012] <1. Overall configuration of the imaging device> First, the overall configuration of an imaging device to which the technology according to the present disclosure is applied will be described with reference to Fig. 1. Fig. 1 is a schematic explanatory diagram illustrating the overall configuration of an imaging device to which the technology according to the present disclosure is applied.

[0013] As shown in FIG. 1, an imaging device 1 to which the technology disclosed herein is applied includes, for example, a pixel array section 3 in which pixels 2 are two-dimensionally arranged in a matrix, a vertical drive circuit 4, a column signal processing circuit 5, a horizontal drive circuit 6, an output circuit 7, and a control circuit 8.

[0014] The pixel array section 3, the vertical drive circuit 4, the column signal processing circuit 5, the horizontal drive circuit 6, the output circuit 7, and the control circuit 8 are provided on a semiconductor substrate such as silicon (Si). The pixel array section 3, the vertical drive circuit 4, the column signal processing circuit 5, the horizontal drive circuit 6, the output circuit 7, and the control circuit 8 may be provided on one semiconductor substrate, or may be provided separately on two or more semiconductor substrates.

[0015] The pixel 2 includes a photoelectric conversion unit and a pixel circuit that converts the electric charge generated by the photoelectric conversion unit into a pixel signal. The photoelectric conversion unit includes, for example, a photodiode. The pixel circuit includes, for example, four MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) such as a transfer transistor, an amplification transistor, a selection transistor, and a reset transistor.

[0016] Moreover, the pixel 2 may further include a charge holding unit to realize a global shutter operation. The global shutter operation is a shutter operation in which exposure is started and ended simultaneously for all pixels 2 effective for imaging. The charge holding unit can temporarily hold the charge photoelectrically converted by simultaneous exposure of all pixels until a pixel signal is obtained from each of the pixels 2.

[0017] The pixels 2 may be provided in a pixel sharing structure. The pixel sharing structure is a structure in which a part or the whole of a pixel circuit is shared between a plurality of adjacent pixels 2. For example, the adjacent pixels 2 may share an amplification transistor, a selection transistor, and a reset transistor. In such a case, each of the adjacent pixels 2 is composed of a photodiode, a transfer transistor, one floating diffusion shared by the adjacent pixels 2, one amplification transistor also shared in the same way, one selection transistor also shared in the same way, and one reset transistor also shared in the same way.

[0018] The control circuit 8 controls the operation of each part of the imaging device 1. Specifically, the control circuit 8 generates clock signals and control signals that serve as a reference for the operation of the vertical drive circuit 4, the column signal processing circuit 5, the horizontal drive circuit 6, etc., based on a vertical synchronization signal, a horizontal synchronization signal, and a master clock. In addition, the control circuit 8 outputs the generated clock signals and control signals to the vertical drive circuit 4, the column signal processing circuit 5, the horizontal drive circuit 6, etc.

[0019] The vertical drive circuit 4 includes, for example, a shift register. The vertical drive circuit 4 selects pixel drive wirings 10 and supplies a pulse signal to the selected pixel drive wirings 10 to drive the pixels 2 row by row. Specifically, the vertical drive circuit 4 sequentially selects and scans each of the pixels 2 included in the pixel array unit 3 row by row in the vertical direction. This allows the vertical drive circuit 4 to extract a pixel signal corresponding to the amount of charge obtained by photoelectric conversion from each of the pixels 2 and supply it to the column signal processing circuit 5.

[0020] The column signal processing circuit 5 is provided for each column of the pixels 2 in the pixel array unit 3, and performs noise removal processing and the like on pixel signals output from the pixels 2 for each column of the pixels 2. For example, the column signal processing circuit 5 may perform correlated double sampling (CDS) processing for removing fixed pattern noise specific to the pixels 2, AD (Analog-Digital) conversion processing and the like on the pixel signals.

[0021] The horizontal drive circuit 6 includes, for example, a shift register. The horizontal drive circuit 6 sequentially outputs horizontal scanning pulses to sequentially select each of the column signal processing circuits 5, and causes each of the column signal processing circuits 5 to output a pixel signal to a horizontal signal line 11.

[0022] The output circuit 7 outputs the pixel signals sequentially supplied from each of the column signal processing circuits 5 via the horizontal signal line 11 to the outside of the imaging device 1. For example, the output circuit 7 may perform various digital signal processing such as buffering, black level adjustment, or column variation correction on the pixel signals supplied from each of the column signal processing circuits 5, and then output the pixel signals after the signal processing to the outside of the imaging device 1.

[0023] The imaging device 1 having the above configuration is a so-called column AD type CMOS (Complementary MOS) image sensor in which a column signal processing circuit 5 that performs CDS processing and AD conversion processing is provided for each column of pixels 2.

[0024] The technology according to the present disclosure can be applied to, for example, an imaging device 1 having the above-described configuration. According to the technology according to the present disclosure, the imaging device 1 can effectively block stray light generated inside the imaging device 1, thereby preventing the stray light from entering the photoelectric conversion unit or the charge storage unit. As a result, the imaging device 1 to which the technology according to the present disclosure is applied can further prevent crosstalk between adjacent pixels 2.

[0025] 2. First embodiment (2.1. Pixel Structure) Next, the configuration of the pixel 2 in the imaging device 1 according to the first embodiment of the present disclosure will be described with reference to Fig. 2. Fig. 2 is a vertical cross-sectional view showing the configuration of the pixel 2 in the imaging device 1 according to this embodiment.

[0026] As shown in FIG. 2, the imaging device 1 includes, for example, a semiconductor substrate 30 and a multilayer wiring layer 20.

[0027] The semiconductor substrate 30 is a substrate made of a semiconductor such as silicon. The semiconductor substrate 30 includes, for example, a photoelectric conversion unit (PD) 31 and a charge holding unit (MEM) 32 for each pixel 2. The photoelectric conversion unit 31 and the charge holding unit 32 can be configured, for example, by providing a second conductivity type (e.g., n-type) region inside a first conductivity type (e.g., p-type) region of the semiconductor substrate 30.

[0028] The photoelectric conversion unit 31 is, for example, a photodiode, and generates charges by photoelectrically converting light incident on the pixel 2. The charge holding unit 32 is an area capable of holding the charges generated by the photoelectric conversion unit 31. The charge holding unit 32 can temporarily hold the charges generated by the photoelectric conversion unit 31 until the pixels 2 are sequentially driven and the pixel signals are read out. Therefore, by providing the charge holding unit 32 for each pixel 2, the imaging device 1 can realize a global shutter operation that exposes all pixels simultaneously.

[0029] The multilayer wiring layer 20 is provided on one main surface opposite to the light receiving surface side of the semiconductor substrate 30. The multilayer wiring layer 20 includes, for example, a plurality of wiring layers 21, a plurality of interlayer insulating layers 22 that insulate the plurality of wiring layers 21 in the stacking direction, and a plurality of contact plugs 23 that are provided penetrating the interlayer insulating layers 22 and thereby electrically connect the plurality of wiring layers 21. The multilayer wiring layer 20 includes, for example, transistors Tr such as a transfer transistor, an amplification transistor, a selection transistor, and a reset transistor included in the pixel circuit, and wiring that electrically connects each of the transistors Tr.

[0030] Further, a gate electrode 25 of a transfer transistor that controls the transfer or removal of charges to the charge retention portion 32 is provided in the multilayer wiring layer 20 below the region of the semiconductor substrate 30 where the charge retention portion 32 is provided. The gate electrode 25 of the transfer transistor is electrically connected to the wiring layer 21 via a contact plug 26, and the transfer or removal of charges to the charge retention portion 32 can be controlled by a voltage applied from the wiring layer 21.

[0031] Here, when stray light or the like is incident on the charge retention section 32 that temporarily retains charge, new charge is generated in the charge retention section 32, which may increase the amount of charge retained in the charge retention section 32. Therefore, in the imaging device 1, a light shielding structure 33 is provided on the semiconductor substrate 30, and a wiring light shielding film 24 is provided on the multilayer wiring layer 20, thereby suppressing the incidence of light on the charge retention section 32.

[0032] The light-shielding structure 33 includes, for example, a first light-shielding film 33A, a second light-shielding film 33B, and a third light-shielding film 33C, and is made of a metal having light-shielding properties such as tungsten (W) so as to cover the region in which the charge retention unit 32 is provided.

[0033] The first light-shielding film 33A is provided between the charge holding section 32 and the photoelectric conversion section 31, and extends in the thickness direction of the semiconductor substrate 30. The first light-shielding film 33A is provided to prevent light that has been transmitted through the semiconductor substrate 30 without being absorbed by the photoelectric conversion section 31 from being incident on the charge holding section 32.

[0034] The second light-shielding film 33B is provided to extend in an in-plane direction on one main surface of the semiconductor substrate 30 corresponding to an area where the charge retention portion 32 is provided. The second light-shielding film 33B can prevent light incident from the light-receiving surface side of the semiconductor substrate 30 from being directly or indirectly incident on the charge retention portion 32.

[0035] The third light-shielding film 33C is provided between the photoelectric conversion unit 31 and the charge retention unit 32 of the adjacent pixel 2. The third light-shielding film 33C can prevent light incident on the adjacent pixel 2 from transmitting through the semiconductor substrate 30 and entering the charge retention unit 32.

[0036] The wiring light-shielding film 24 is provided so as to cover the gate electrode 25 of the transfer transistor from the multilayer wiring layer 20 side. The wiring light-shielding film 24 can prevent light that passes through the semiconductor substrate 30 without being absorbed by the photoelectric conversion unit 31 and is reflected by the wiring layer 21 from entering the charge retention unit 32 from the multilayer wiring layer 20 side.

[0037] Furthermore, an opening 24A for connecting the contact plug 26 to the gate electrode 25 of the transfer transistor is provided in the wiring light-shielding film 24. Therefore, there is a possibility that light reflected by the wiring layer 21 may enter the charge retention portion 32 via the opening 24A through which the contact plug 26 passes.

[0038] Therefore, in this embodiment, the contact plug 26 electrically connected to the gate electrode 25 of the transfer transistor is provided with a protruding portion 27 that protrudes in the in-plane direction of the semiconductor substrate 30 and covers the opening 24A. Specifically, the protruding portion 27 is provided in an area larger than the area where the opening 24A is provided, and is provided so as to partially overlap the area where the wiring light shielding film 24 is provided when one main surface of the semiconductor substrate 30 is viewed in plan. With this, the charge holding portion 32 can doubly shield reflected light from the multilayer wiring layer 20 side by both the wiring light shielding film 24 and the protruding portion 27. Therefore, according to this embodiment, by suppressing stray light incident on the charge holding portion 32, crosstalk between adjacent pixels 2, or a decrease in resolution or color reproduction characteristics, can be suppressed.

[0039] An interlayer insulating layer 41 is further provided on one main surface of the light-receiving surface side of the semiconductor substrate 30, the interlayer insulating layer 41 being made of an insulating material having high light transmittance. The interlayer insulating layer 41 may be made of an insulating material having a transmittance of approximately 70% or more for light in the visible light band, for example. Alternatively, the interlayer insulating layer 41 may be made of an insulating material having a refractive index smaller than that of the semiconductor substrate 30 in order to suppress reflection of incident light.

[0040] The interlayer insulating layer 41 may be formed of, for example, silicon oxide (SiO2), silicon nitride (SiN), silicon oxynitride (SiON), hafnium oxide (HfO2), aluminum oxide (Al2O3), zirconium oxide (ZrO2), tantalum oxide (Ta2O5), titanium oxide (TiO2), lanthanum oxide (La2O3), praseodymium oxide (Pr2O3), cerium oxide (CeO2), neodymium oxide (Nd2O3), proton oxide (BP), or the like. The insulating material may be formed from an insulating material such as thulium oxide (Pm2O3), samarium oxide (Sm2O3), europium oxide (Eu2O3), gadolinium oxide (Gd2O3), terbium oxide (Tb2O3), dysprosium oxide (Dy2O3), holmium oxide (Ho2O3), thulium oxide (Tm2O3), ytterbium oxide (Yb2O3), lutetium oxide (Lu2O3), or yttrium oxide (Y2O3).

[0041] A sub-on-chip lens 42 is further provided on the light receiving surface side of the interlayer insulating layer 41. The sub-on-chip lens 42 is provided as a convex lens that collects incident light to the pixel 2 so that the incident light is efficiently incident on the photoelectric conversion unit 31. The sub-on-chip lens 42 may be formed of a transparent organic resin such as a styrene resin, an acrylic resin, a styrene-acrylic copolymer resin, or a siloxane resin so that the light transmittance in the visible light band is 70% or more. The sub-on-chip lens 42 may be embedded in a planarization film 43 formed of an organic resin or the like.

[0042] A pixel separation structure 46 is provided in the interlayer insulating layer 41, the sub on-chip lenses 42, and the planarization film 43 between the pixels 2 so as to penetrate the interlayer insulating layer 41, the sub on-chip lenses 42, and the planarization film 43. The pixel separation structure 46 is formed of a metal having light blocking properties such as tungsten (W). The pixel separation structure 46 blocks light that is obliquely incident between the pixels 2, thereby suppressing crosstalk between adjacent pixels 2.

[0043] A main on-chip lens 45 is further provided on the light-receiving surface side of the planarization film 43 via a color filter layer 44. The main on-chip lens 45, together with the sub on-chip lens 42, can improve the light-collection ability of incident light in the pixel 2 to the photoelectric conversion unit 31.

[0044] The color filter layer 44 may be formed, for example, by applying a resin containing a red, green, or blue pigment or dye to the light receiving surface side of the planarization film 43. The color filter layer 44 may be provided so that the red, green, or blue colors are arranged in a Bayer array, or may be provided so that the red, green, or blue colors are arranged in another array.

[0045] Similar to the sub on-chip lens 42, the main on-chip lens 45 is provided as a convex lens that condenses incident light on the pixel 2 so that the incident light can efficiently enter the photoelectric conversion unit 31. The main on-chip lens 45 may be formed of a transparent organic resin such as a styrene resin, an acrylic resin, a styrene-acrylic copolymer resin, or a siloxane resin so that the light transmittance in the visible light band is 70% or more.

[0046] In the imaging device 1 according to this embodiment, a contact plug 26 electrically connected to a gate electrode 25 of a transfer transistor that controls the inflow and outflow of charges held in the charge holding portion 32 is provided with an overhanging portion 27 that overhangs in the in-plane direction of the semiconductor substrate 30. This allows the opening 24A provided in the wiring light shielding film 24 to pass the contact plug 26 to be covered by the overhanging portion 27, thereby further suppressing stray light entering the charge holding portion 32.

[0047] (2.2. Configuration example of extension part) Next, a specific configuration example of the protruding portion 27 provided in the contact plug 26 will be described with reference to FIGS.

[0048] (First configuration example) First, a first configuration example of the protruding portion 27 will be described with reference to Fig. 3. Fig. 3 is a vertical cross-sectional view showing the first configuration example of the protruding portion 27. In Fig. 3, the downward direction facing the figure is the semiconductor substrate 30 side (i.e., the light receiving surface side), and the upward direction facing the figure is the multilayer wiring layer 20 side.

[0049] As shown in FIG. 3, for example, a transfer transistor that controls the inflow and outflow of charges held in the charge holding unit 32 may be provided as a buried type field effect transistor having a gate electrode 250 buried in the semiconductor substrate 30.

[0050] The gate electrode 250 is made of, for example, polysilicon and has a flat portion 250A provided on one main surface of the semiconductor substrate 30 and a recessed portion 250B recessed into the semiconductor substrate 30. A gate insulating film 251 made of, for example, silicon oxide is provided at the interface between the gate electrode 250 and the semiconductor substrate 30 so as to cover the gate electrode 250. Furthermore, a conductive impurity is introduced into a predetermined region of the semiconductor substrate 30, thereby forming a channel in the semiconductor substrate 30 and forming a transfer path for charges from the charge holding portion 32.

[0051] A sidewall insulating film 252 is provided on a side surface of the flat portion 250A of the gate electrode 250. The sidewall insulating film 252 is made of an insulating material such as silicon oxide, silicon nitride, or silicon oxynitride, and is provided in order to control with high precision the region where conductive impurities are introduced into the semiconductor substrate 30. The sidewall insulating film 252 can be formed, for example, by forming an insulating layer containing an insulating material so as to cover the upper surface of the flat portion 250A of the gate electrode 250, and then anisotropically etching the insulating layer vertically.

[0052] A first insulating layer 223 and a second insulating layer 224 are sequentially provided on an upper surface of the flat portion 250A of the gate electrode 250. Specifically, the first insulating layer 223 and the second insulating layer 224 are uniformly provided on the semiconductor substrate 30 so as to cover the flat portion 250A of the gate electrode 250 and the sidewall insulating film 252. The first insulating layer 223 and the second insulating layer 224 may be made of an insulating material such as silicon oxide, silicon nitride, or silicon oxynitride.

[0053] A wiring light-shielding film 240 is provided on the second insulating layer 224. Specifically, the wiring light-shielding film 240 is provided on the second insulating layer 224 by a metal material having light-shielding properties such as tungsten. An opening 240A is provided in the wiring light-shielding film 240 above the flat portion 250A of the gate electrode 250 to pass a contact plug electrically connected to the gate electrode 250. A barrier layer 241 may be provided on the upper surface of the wiring light-shielding film 240 to suppress diffusion of the metal material forming the wiring light-shielding film 240. The barrier layer 241 can be formed of, for example, titanium, tantalum, titanium nitride, tantalum nitride, or the like.

[0054] A third insulating layer 221 is provided on the wiring light shielding film 240. The third insulating layer 221 is provided uniformly on one main surface of the semiconductor substrate 30 along the shape of the wiring light shielding film 240 so as to cover the upper surface of the wiring light shielding film 240 and the inside of the opening 240A of the wiring light shielding film 240. The third insulating layer 221 may be made of an insulating material such as silicon oxide, silicon nitride, or silicon oxynitride.

[0055] The first contact plug 270 is provided so as to pass through an opening provided in the wiring light shielding film 240 and penetrate the first insulating layer 223, the second insulating layer 224, and the third insulating layer 221, and is electrically connected to the gate electrode 250. Specifically, the first contact plug 270 includes an extension portion 270B that extends from the upper surface of the flat portion 250A of the gate electrode 250 in the thickness direction of the semiconductor substrate 30 to above the third insulating layer 221, and a protruding portion 270A that protrudes in the in-plane direction of the semiconductor substrate 30 along the shape of the third insulating layer 221.

[0056] The overhanging portion 270A is provided so as to cover the opening 240A provided in the wiring light shielding film 240 and overlap with the region where the wiring light shielding film 240 is provided in the in-plane direction of the semiconductor substrate 30. For example, the overhanging portion 270A may be provided so as to cover a region slightly larger than the opening 240A provided in the wiring light shielding film 240 when one main surface of the semiconductor substrate 30 is viewed in a plan view from the thickness direction of the semiconductor substrate 30. The overhanging portion 270A may be provided symmetrically or asymmetrically in the plane of the semiconductor substrate 30. The first contact plug 270 including the overhanging portion 270A can be formed of a metal material having light shielding properties such as tungsten.

[0057] Furthermore, a fourth insulating layer 222 is provided so as to spread over the entire surface of the semiconductor substrate 30 and to bury the first contact plug 270. The fourth insulating layer 222 may be made of an insulating material such as silicon oxide, silicon nitride, or silicon oxynitride.

[0058] A second contact plug 260 is provided on the protruding portion 270A of the first contact plug 270, penetrating the fourth insulating layer 222. The second contact plug 260 may be provided on the protruding portion 270A so as to be coaxial with the extending portion 270B of the first contact plug 270, for example. The second contact plug 260 electrically connects the first contact plug 270 and the wiring layer 21. As a result, a potential is applied to the gate electrode 250 from the wiring layer 21 via the first contact plug 270 and the second contact plug 260. Note that a barrier layer 261 may be provided on the surface of the second contact plug 260 to suppress diffusion of the metal material forming the second contact plug 260. The barrier layer 261 can be formed of, for example, titanium, tantalum, titanium nitride, tantalum nitride, or the like.

[0059] Next, a method for forming the protruding portion 270A according to the first configuration example shown in Fig. 3 will be described with reference to Fig. 4A to Fig. 4D. Fig. 4A to Fig. 4D are vertical cross-sectional views illustrating each step of the method for forming the protruding portion 270A according to the first configuration example.

[0060] 4A, a gate insulating film 251 and a gate electrode 250 are formed on a semiconductor substrate 30 using a known method, and then a sidewall insulating film 252, a first insulating layer 223, and a second insulating layer 224 are formed. Next, a wiring light shielding film 240 is formed on the second insulating layer 224, and then an opening 240A is formed in a region including a region where a first contact plug 270 is to be formed in a later step. Furthermore, a third insulating layer 221 is uniformly formed on the wiring light shielding film 240 and the second insulating layer 224.

[0061] Next, as shown in FIG. 4B, a contact opening 271 is formed inside the opening 240A of the wiring light shielding film 240 by dry etching, penetrating the third insulating layer 221, the second insulating layer 224, and the first insulating layer 223 to expose the gate electrode 250.

[0062] 4C, a light-shielding material such as tungsten is deposited on the third insulating layer 221, the contact opening 271 is filled with the light-shielding material, and then the light-shielding material is partially removed by etching to form a first contact plug 270. For example, the light-shielding material is removed from above the third insulating layer 221 so that a part of the region where the extension portion 270A of the first contact plug 270 is provided and a part of the region where the wiring light-shielding film 240 is provided overlap in the thickness direction of the semiconductor substrate 30. As a result, a first contact plug 270 is formed in which the light-shielding material deposited inside the contact opening 271 serves as the extension portion 270B and the light-shielding material deposited on the third insulating layer 221 serves as the extension portion 270A.

[0063] 4D, a fourth insulating layer 222 is uniformly formed on the first contact plug 270 and the third insulating layer 221 by using CVD (Chemical Vapor Deposition) or the like, and then the fourth insulating layer 222 is planarized by CMP (Chemical Mechanical Polishing). Next, an opening is formed by etching or the like to penetrate the fourth insulating layer 222 and expose the first contact plug 270, and then the opening is filled with tungsten or the like to form the second contact plug 260. Next, a wiring layer 21 that is electrically connected to the second contact plug 260 is formed.

[0064] The above steps can form the overhanging portion 270A according to the first configuration example. In the overhanging portion 270A according to the first configuration example, the overhanging portion 270A of the first contact plug 270 is provided on the side opposite to the side on which the semiconductor substrate 30 is provided with respect to the wiring light-shielding film 240 (i.e., the upper side in FIG. 3). According to the first configuration example, the opening 240A provided on the gate electrode 250 of the wiring light-shielding film 240 is completely shielded by the overhanging portion 270A of the first contact plug 270 when viewed in plan from the thickness direction of the semiconductor substrate 30. Therefore, the overhanging portion 270A can shield the opening 240A provided in the wiring light-shielding film 240 to provide the first contact plug 270 electrically connected to the gate electrode 250 in the thickness direction of the semiconductor substrate 30. Therefore, the overhanging portion 270A can suppress stray light from the multilayer wiring layer 20 to the semiconductor substrate 30.

[0065] (Second configuration example) Next, a second configuration example of the protruding portion 27 will be described with reference to Fig. 5. Fig. 5 is a vertical cross-sectional view showing the second configuration example of the protruding portion 27. In Fig. 5, the downward direction facing the figure is the semiconductor substrate 30 side (i.e., the light receiving surface side), and the upward direction facing the figure is the multilayer wiring layer 20 side.

[0066] 5, the second configuration example is different from the first configuration example in that a protruding portion 270A of a first contact plug 270 is provided on the side where the semiconductor substrate 30 is provided (i.e., the lower side in FIG. 5) of the wiring light shielding film 240. Note that the gate electrode 250, the gate insulating film 251, the sidewall insulating film 252, the first insulating layer 223, the second insulating layer 224, and the fourth insulating layer 222 are as described in FIG. 3, and therefore description thereof will be omitted here.

[0067] The first contact plug 270 is provided on the second insulating layer 224 corresponding to the flat portion 250A of the gate electrode 250, and is electrically connected to the gate electrode 250. The first contact plug 270 includes an extension portion 270B provided penetrating the first insulating layer 223 and the second insulating layer 224, and a protruding portion 270A provided on the second insulating layer 224 so as to protrude in the in-plane direction of the semiconductor substrate 30.

[0068] The overhanging portion 270A is provided in an area larger than the opening 240A provided in the wiring light-shielding film 240 to allow the second contact plug 260 to pass therethrough. For example, the overhanging portion 270A may be provided in a planar area corresponding to the upper surface of the planar portion 250A of the gate electrode 250. The overhanging portion 270A may be provided symmetrically or asymmetrically in the plane of the semiconductor substrate 30. The first contact plug 270 including the overhanging portion 270A may be formed of a metal material having light-shielding properties, such as tungsten.

[0069] Furthermore, a third insulating layer 221 is provided on the second insulating layer 224 and the protruding portion 270A of the first contact plug 270. The third insulating layer 221 is provided uniformly on one main surface of the semiconductor substrate 30 so as to cover the gate electrode 250 including the protruding portion 270A of the first contact plug 270. The third insulating layer 221 may be provided using an insulating material such as silicon oxide, silicon nitride, or silicon oxynitride.

[0070] A wiring light-shielding film 240 is provided on the third insulating layer 221. Specifically, the wiring light-shielding film 240 is provided on the third insulating layer 221 by a metal material having light-shielding properties such as tungsten. An opening 240A is provided in the wiring light-shielding film 240 above the flat portion 250A of the gate electrode 250 to pass a contact plug electrically connected to the gate electrode 250. The opening 240A provided in the wiring light-shielding film 240 may be formed in an area slightly smaller than the area in which the protruding portion 270A of the first contact plug 270 is provided. A barrier layer 241 may be provided on the upper surface of the wiring light-shielding film 240 to suppress diffusion of the metal material forming the wiring light-shielding film 240. The barrier layer 241 can be formed of, for example, titanium, tantalum, titanium nitride, tantalum nitride, or the like.

[0071] A second contact plug 260 is provided on the overhanging portion 270A of the first contact plug 270, passing through the opening 240A of the wiring light shielding film 240 and penetrating the third insulating layer 221 and the fourth insulating layer 222. The second contact plug 260 may be provided on the overhanging portion 270A so as to be coaxial with the extension portion 270B of the first contact plug 270, for example. The second contact plug 260 electrically connects the first contact plug 270 and the wiring layer 21. Thereby, a potential is applied to the gate electrode 250 from the wiring layer 21 via the first contact plug 270 and the second contact plug 260. Note that a barrier layer 261 may be provided on the surface of the second contact plug 260 to suppress diffusion of the metal material forming the second contact plug 260. The barrier layer 261 can be formed of, for example, titanium, tantalum, titanium nitride, tantalum nitride, or the like.

[0072] Next, a method for forming the protruding portion 270A according to the second configuration example shown in Fig. 5 will be described with reference to Fig. 6A to Fig. 6E. Fig. 6A to Fig. 6E are vertical cross-sectional views illustrating each step of the method for forming the protruding portion 270A according to the second configuration example.

[0073] First, as shown in FIG. 6A, a gate insulating film 251 and a gate electrode 250 are formed on a semiconductor substrate 30 using a known method, and then a sidewall insulating film 252, a first insulating layer 223, and a second insulating layer 224 are formed.

[0074] Next, as shown in FIG. 6B, a contact opening 271 is formed through the second insulating layer 224 and the first insulating layer 223 to expose the gate electrode 250 using dry etching.

[0075] 6C, a light-shielding material such as tungsten is deposited on the second insulating layer 224, the contact opening 271 is filled with the light-shielding material, and then the light-shielding material is removed by etching except for the upper surface of the gate electrode 250 to form a first contact plug 270. As a result, a first contact plug 270 is formed in which the light-shielding material deposited inside the contact opening 271 serves as an extension portion 270B and the light-shielding material deposited on the second insulating layer 224 serves as a protruding portion 270A.

[0076] 6D, a third insulating layer 221 is uniformly formed on the first contact plug 270 and the second insulating layer 224. Subsequently, a wiring light shielding film 240 is formed on the third insulating layer 221, and then an opening 240A is formed in a region including a region where a second contact plug 260 connected to the gate electrode 250 is to be formed.

[0077] 6E, a fourth insulating layer 222 is uniformly formed on the wiring light shielding film 240 and the third insulating layer 221 by using CVD (Chemical Vapor Deposition) or the like, and then the fourth insulating layer 222 is planarized by CMP (Chemical Mechanical Polishing). Next, an opening is formed by penetrating the third insulating layer 221 and the fourth insulating layer 222 by etching or the like to expose the first contact plug 270, and then the opening is filled with tungsten or the like to form the second contact plug 260. Next, a wiring layer 21 electrically connected to the second contact plug 260 is formed.

[0078] The above steps can form the overhanging portion 270A according to the second configuration example. In the overhanging portion 270A according to the second configuration example, the overhanging portion 270A of the first contact plug 270 is provided on the side of the wiring light-shielding film 240 on which the semiconductor substrate 30 is provided (i.e., the lower side in FIG. 5). According to the second configuration example, similarly to the first configuration example, the opening 240A provided on the gate electrode 250 of the wiring light-shielding film 240 is completely shielded by the overhanging portion 270A of the first contact plug 270 when viewed in plan from the thickness direction of the semiconductor substrate 30. Therefore, the overhanging portion 270A can suppress stray light from the multilayer wiring layer 20 to the semiconductor substrate 30.

[0079] (2.3. Modifications) Next, modified examples of the imaging device 1 according to this embodiment will be described with reference to Fig. 7 to Fig. 10. The technology according to this embodiment can be applied to devices other than the imaging device 1 that realizes a global shutter operation by including the charge holding unit 32 as shown in Fig. 2. Figs. 7 to 10 are vertical cross-sectional views showing examples of imaging devices to which the technology according to this embodiment can be applied.

[0080] For example, as shown in FIG. 7, the technique according to this embodiment can also be applied to an imaging device that realizes a global shutter operation by using a floating diffusion region (FD) 34 having a predetermined capacitance instead of the charge holding unit 32.

[0081] 7, a floating diffusion region 34 is provided instead of the charge retention portion 32, and therefore the light shielding structure 33 and the wiring light shielding film 24 are not provided. The pixel isolation structure 46 is composed of a pixel insulating film 46A and a pixel defining film 46B. The pixel insulating film 46A is made of an insulating material and extends in the thickness direction of the semiconductor substrate 30, thereby electrically isolating the pixels 2 from each other. The pixel defining film 46B is made of tungsten or the like having light shielding properties, and defines the range of the pixel 2.

[0082] In such an imaging device, the overhang 27 is provided in the contact plug 26 connected to the gate electrode 25 of the field effect transistor that controls the flow of charge into and out of the floating diffusion region 34. In this way, the overhang 27 can shield the floating diffusion region 34 from light that passes through the semiconductor substrate 30 in the adjacent pixel 2 and is reflected by the wiring layer 21. Therefore, the overhang 27 can suppress crosstalk between adjacent pixels 2 even in such an imaging device.

[0083] Furthermore, as shown in FIG. 8, the technique according to this embodiment can also be applied to an imaging device in which a charge holding section 32 is stacked on a photoelectric conversion section 31 in the thickness direction of a semiconductor substrate 30.

[0084] 8, the light-shielding structure 33 is provided between the charge holding section 32 and the photoelectric conversion section, and on the side of the charge holding section 32. The pixel separation structure 46 is composed of a pixel insulating film 46A and a pixel defining film 46B. The pixel insulating film 46A is made of an insulating material and extends in the thickness direction of the semiconductor substrate 30, thereby electrically isolating the pixels 2 from each other. The pixel defining film 46B is made of tungsten or the like having light-shielding properties, and defines the range of the pixel 2 and prevents reflected light, etc. from entering an adjacent pixel 2 in the region where the auxiliary on-chip lens 42 is provided.

[0085] In such an imaging device, the overhanging portion 27 is provided in the contact plug 26 electrically connected to the gate electrode 25 of a field effect transistor that controls the flow of charge to and from the charge retention portion 32. In this manner, the overhanging portion 27 can shield the charge retention portion 32 from light that passes through the semiconductor substrate 30 in the adjacent pixel 2 and is reflected by the wiring layer 21. Therefore, the overhanging portion 27 can suppress crosstalk between adjacent pixels 2 even in such an imaging device.

[0086] In addition, as shown in Fig. 9, the technology according to the present embodiment can also be applied to an imaging device for vehicle use that has pixels of different sizes. In an imaging device that has pixels of different sizes, it is possible to operate the device by using pixel signals of small pixels in a bright environment and pixel signals of large pixels in a dark environment. Therefore, an imaging device that has pixels of different sizes can expand the dynamic range of the detectable light amount.

[0087] 9 does not include a charge retention portion 32, and therefore does not include a light shielding structure 33 and a wiring light shielding film 24. The pixel separation structure 46 is composed of a pixel insulating film 46A and a pixel defining film 46B. The pixel insulating film 46A is made of an insulating material and extends in the thickness direction of the semiconductor substrate 30, thereby electrically isolating the pixels 2 from each other. The pixel defining film 46B is made of tungsten or the like having light shielding properties, and defines the range of the pixel 2.

[0088] In such an imaging device, the protrusion 27 is provided in a contact plug 26 electrically connected to a gate electrode 25 of a field effect transistor provided between the pixels 2. In an imaging device in which pixels of different sizes are mixed, the presence or absence of a field effect transistor between the pixels 2 varies depending on the arrangement of the pixels 2, and therefore the presence of a field effect transistor between the pixels 2 may reduce the light blocking property between the pixels 2.

[0089] According to the technology of the present embodiment, by providing the overhanging portion 27, it is possible to prevent a decrease in the light blocking property between the pixels 2 in which the field effect transistors are present by blocking the light that passes through the semiconductor substrate 30 in the adjacent pixels 2 and is reflected by the wiring layer 21. Therefore, the overhanging portion 27 can prevent crosstalk between the adjacent pixels 2 even in such an imaging device.

[0090] As shown in FIG. 10, the technique according to this embodiment is also applicable to a back-illuminated imaging device.

[0091] 10 does not include a charge retention portion 32, and therefore does not include a light shielding structure 33 and a wiring light shielding film 24. The pixel isolation structure 46 is composed of a pixel insulating film 46A and a pixel defining film 46B. The pixel insulating film 46A is made of an insulating material and extends in the thickness direction of the semiconductor substrate 30, thereby electrically isolating the pixels 2. The pixel defining film 46B is made of tungsten or the like having light shielding properties, and defines the range of the pixel 2 and prevents reflected light, etc. from entering an adjacent pixel 2 in the region where the auxiliary on-chip lens 42 is provided.

[0092] In such an imaging device, the protruding portion 27 is provided in a contact plug 26 electrically connected to a gate electrode 25 of a field effect transistor provided between the pixels 2. In a back-illuminated imaging device, a multilayer wiring layer 20 is provided on the side opposite to the light receiving surface side with respect to the photoelectric conversion section 31, and the layout of the wiring layer 21 provided in the multilayer wiring layer 20 varies depending on, for example, the arrangement direction of the pixels 2. As a result, the amount of light reflected by the wiring layer 21 of the multilayer wiring layer 20 varies depending on, for example, the arrangement direction of the pixels 2, and therefore, a difference in resolution or brightness may occur for each pixel 2 depending on the layout of the wiring layer 21.

[0093] According to the technology of the present embodiment, by providing the overhanging portion 27, it is possible to block light that passes through the semiconductor substrate 30 in the adjacent pixel 2 and is reflected by the wiring layer 21, thereby suppressing crosstalk between the adjacent pixels 2 due to stray light. Therefore, the overhanging portion 27 can suppress the difference in resolution or brightness between the pixels 2 due to the layout of the wiring layer 21.

[0094] 3. Second embodiment (3.1. Pixel Structure) Next, a configuration of a pixel 2 in an imaging device according to a second embodiment of the present disclosure will be described with reference to Fig. 11. Fig. 11 is a plan view showing an example of a pixel 2 in the imaging device according to this embodiment.

[0095] 11, the pixel 2 has, as the photoelectric conversion unit 70, a photodiode configured by forming a second conductivity type (e.g., n-type) region inside a first conductivity type (e.g., p-type) region formed in the semiconductor substrate 51. The photoelectric conversion unit 70 can generate and accumulate charges in an amount corresponding to incident light by photoelectric conversion.

[0096] The pixel 2 also includes a first transfer gate (gate electrode 61), a charge holding portion 71, a second transfer gate (gate electrode 62), a floating diffusion region 72, a reset transistor (gate electrode 63), an amplification transistor (gate electrode 64), and a selection transistor (gate electrode 65).

[0097] The gate electrode 61 of the first transfer gate is provided between the photoelectric conversion unit 70 and the charge retention unit 71 and above the charge retention unit 71, with a gate insulating film interposed between them. In the first transfer gate, a transfer pulse is applied to the gate electrode 61 via a contact, whereby the charges stored in the photoelectric conversion unit 70 are transferred to the charge retention unit 71.

[0098] The charge holding unit 71 is provided under the gate electrode 61 of the first transfer gate by forming a second conductivity type (e.g., n type) region inside a first conductivity type (e.g., p type) region of the semiconductor substrate 51. The charge holding unit 71 temporarily holds the charge transferred from the photoelectric conversion unit 70 by the first transfer gate.

[0099] The gate electrode 62 of the second transfer gate is provided between the charge holding portion 71 and the floating diffusion region 72 via a gate insulating film. In the second transfer gate, a transfer pulse is applied to the gate electrode 62 via a contact, whereby the charge held in the charge holding portion 71 is transferred to the floating diffusion region 72.

[0100] The floating diffusion region 72 is a second conductivity type (e.g., n-type) region of the semiconductor substrate 51, and accumulates electric charges to convert the accumulated electric charges into a voltage. A contact 73 is electrically connected to the floating diffusion region 72 via a contact wiring layer 83.

[0101] The gate electrode 63 of the reset transistor is provided adjacent to the floating diffusion region 72. In the reset transistor, the source is electrically connected to the floating diffusion region 72, and the drain is electrically connected to a power supply by a contact 74 via a contact wiring layer 84. In the reset transistor, when a reset pulse is applied to the gate electrode 63 via the contact, charge is discharged from the floating diffusion region 72 to the power supply, and the floating diffusion region 72 is reset.

[0102] The gate electrode 64 of the amplifier transistor is provided on the opposite side to the gate electrode 63 of the reset transistor with respect to the contact wiring layer 84. In the amplifier transistor, the source is electrically connected to the drain of the select transistor, and the drain is electrically connected to a power supply by a contact 74 via the contact wiring layer 84. In the amplifier transistor, the floating diffusion region 72 is electrically connected to the gate electrode 64 via the contact.

[0103] The gate electrode 65 of the selection transistor is provided adjacent to the gate electrode 64 of the amplification transistor. In the selection transistor, the source is electrically connected to the vertical signal line by a contact 75 via a contact wiring layer 85, and the drain is electrically connected to the source of the amplification transistor. In the selection transistor, a selection pulse is applied to the gate electrode 64 via the contact, thereby selecting the pixel 2 as a target for reading out a pixel signal. When the selection transistor is turned on, the amplification transistor outputs a pixel signal corresponding to the charge accumulated in the floating diffusion region 72 to the vertical signal line via the selection transistor, the contact wiring layer 85, and the contact 75.

[0104] Furthermore, the pixel 2 includes a charge drain gate (gate electrode 66) and a charge drain portion .

[0105] The gate electrode 66 of the charge drain gate is provided between the photoelectric conversion unit 70 and the charge drain unit 76 via a gate insulating film. In the charge drain gate, the charge stored in the photoelectric conversion unit 70 is transferred to the charge drain unit 76 by applying a control pulse to the gate electrode 66 via a contact.

[0106] The charge drain section 76 is provided in a second conductivity type (e.g., n-type) region of the semiconductor substrate 51, and is electrically connected to a power supply via a contact wiring layer 86 and a contact 77. The charge drain gate and the charge drain section 76 can prevent the photoelectric conversion section 70 from being saturated and the charge from overflowing during a period in which a pixel signal is read out after exposure of the pixel 2 is completed.

[0107] 11, a light-shielding film made of tungsten or the like is provided on the upper surface of the pixel 2 via an insulating layer. The light-shielding film has openings, for example, in a region corresponding to the light receiving portion of the photoelectric conversion unit 70 and in a region where each of the contacts is formed. The light-shielding film can suppress the incidence of light on the charge retention unit 71 and the floating diffusion region 72 other than the photoelectric conversion unit 70, which causes noise in the pixel signal.

[0108] However, since the light-shielding film has openings that allow each of the contacts to pass through, there is a possibility that stray light may enter the charge accumulation region of the semiconductor substrate 51 through the openings. The charge accumulation region is a region in the pixel 2 that includes the photoelectric conversion unit 70 capable of accumulating charges, the charge holding unit 71, and the floating diffusion region 72. In the charge accumulation region, there is a possibility that photoelectric conversion occurs inside the semiconductor substrate 51 due to the incidence of light, and new charges are generated. For this reason, it is important to suppress reflected light that enters the semiconductor substrate 51 in the charge accumulation region.

[0109] In the imaging device according to this embodiment, in order to further suppress the incidence of light into the semiconductor substrate 51 in the charge accumulation region, the contact is provided in a region other than the charge accumulation region, and the opening formed in the light shielding film is provided in a region other than the charge accumulation region. Specifically, the contact 73 electrically connected to the floating diffusion region 72 is provided in a non-charge accumulation region such as an element isolation layer, and is electrically connected to the floating diffusion region 72 by a contact wiring layer 83 that is wired in the in-plane direction of the semiconductor substrate 51. According to this, the opening formed in the shielding film to provide the contact 73 is not above the floating diffusion region 72 but above the element isolation layer. Therefore, the imaging device according to this embodiment can suppress the direct incidence of light into the floating diffusion region 72.

[0110] Here, the non-charge accumulation region is a region of the pixel 2 excluding the charge accumulation region. Specifically, the non-charge accumulation region is a region of the pixel 2 in which an element isolation layer made of an insulating material is provided, a region in which electrodes or wiring are provided, and a region of a readout circuit (i.e., a circuit including an amplification transistor, a selection transistor, and a reset transistor) provided in a stage subsequent to the conversion of charges into voltages in the floating diffusion region 72. In these non-charge accumulation regions, the incidence of light is unlikely to cause noise in pixel signals, and therefore the influence of the incidence of light is reduced even when an opening is provided in the light-shielding film.

[0111] Furthermore, the contacts 74, 75, and 77 electrically connected to the semiconductor substrate 51 may be provided in a non-charge accumulation region such as an element isolation layer, similar to the contact 73, and electrically connected to the semiconductor substrate 51 via the contact wiring layers 84, 85, and 86. This can prevent light from being directly incident on the semiconductor substrate 51 through openings provided in the light-shielding film to pass the contacts 74, 75, and 77. This can further prevent light incident on the semiconductor substrate 51 from propagating through the semiconductor substrate 51 and entering the photoelectric conversion unit 70, the charge retention unit 71, or the floating diffusion region 72.

[0112] (3.2. Example of Contact Wiring Layer Configuration) Next, with reference to Figures 12 and 13, a specific configuration example of the contact 73 and the contact wiring layer 83 will be described by showing a cross section along the C-CC cutting line in Figure 11. Figure 12 is a vertical cross-sectional view showing the cross-sectional structure along the C-CC cutting line in Figure 11. Figure 13 is a vertical cross-sectional view showing a modified example of the cross-sectional structure shown in Figure 12.

[0113] 12, a floating diffusion region 72 of a second conductivity type (e.g., n-type) is provided in a semiconductor substrate 51. A first insulating layer 521 made of an insulating material such as silicon oxide, silicon nitride, or silicon oxynitride is provided on the semiconductor substrate 51, and a contact wiring layer 83 electrically connected to the floating diffusion region 72 via a plug 580 is provided on the first insulating layer 521.

[0114] The first insulating layer 521 functions as a gate insulating film for the adjacent reset transistor. For this reason, a gate electrode 63 of the reset transistor is provided on the first insulating layer 521 on the CC end side.

[0115] The contact wiring layer 83 extends, for example, up to above an element isolation layer 513 formed by embedding silicon oxide or the like in the semiconductor substrate 51, and is electrically connected to the contact 73 on the element isolation layer 513. The contact wiring layer 83 and the plug 580 are formed of a conductive material. For example, the contact wiring layer 83 and the plug 580 may be formed of polysilicon into which a conductive impurity is introduced at a high concentration, or may be formed of a metal such as tungsten.

[0116] A light-shielding film 530 is provided on the contact wiring layer 83 and the gate electrode 63 via a second insulating layer 522 made of an insulating material such as silicon oxide, silicon nitride, or silicon oxynitride. The light-shielding film 530 is made of tungsten or the like having light-shielding properties, and is provided along the unevenness of each component provided on the semiconductor substrate 51 in a region excluding the light-receiving portion of the photoelectric conversion unit 70 of the pixel 2.

[0117] The light-shielding film 530 is provided with an opening 530A for passing the contact 73. Specifically, the light-shielding film 530 is provided with an opening 530A on the element isolation layer 513, and the contact 73 is provided through the opening 530A to electrically connect with the floating diffusion region 72 and the contact wiring layer 83. As a result, light passing through the opening 530A of the light-shielding film 530 is incident on the contact wiring layer 83 and the element isolation layer 513 without directly entering the floating diffusion region 72. Therefore, according to the technology of this embodiment, it is possible to suppress the incidence of stray light into the floating diffusion region 72 and the generation of electric charge and noise.

[0118] On the light-shielding film 530, a third insulating layer 523 is provided which is made of an insulating material such as silicon oxide, silicon nitride, or silicon oxynitride.

[0119] Furthermore, as shown in FIG. 13, a silicide region 583 may be provided in the contact wiring layer 83 in the region in contact with the contact 73.

[0120] The silicide region 583 is a region in which a metal-silicon compound such as CoSi (so-called silicide compound) is provided. Since the silicide compound has a higher absorption rate of light in the visible light band than polysilicon or the like, the provision of the silicide region 583 can reduce the transmittance of light passing through the opening 530A of the light-shielding film 530 to the semiconductor substrate 51 side. Therefore, the silicide region 583 can further suppress stray light incident on the floating diffusion region 72, and the charge and noise generated by the stray light.

[0121] (3.3. Method for forming contact wiring layer) (First Forming Method) Next, a first method for forming the contact wiring layer 83 shown in Fig. 12 will be described with reference to Fig. 14A to Fig. 14H. Fig. 14A to Fig. 14H are vertical cross-sectional views illustrating each step of the first method for forming the contact wiring layer 83. The first method is a method for simultaneously forming the contact wiring layer 83 and the gate electrode 63.

[0122] 14A, a first insulating layer 521 is formed on a semiconductor substrate 51 provided with an element isolation layer 513 and a floating diffusion region 72. Then, an opening 591 for forming a plug 580 is formed in the first insulating layer 521 by etching using a patterned resist 590.

[0123] 14B, after removing resist 590, silicon layer 585 is formed on first insulating layer 521. As a result, opening 591 formed in first insulating layer 521 is filled with silicon, and plug 580 is formed.

[0124] Next, as shown in FIG. 14C, portions of silicon layer 585 are removed by etching using patterned resist 592 to form silicon layer 585A, which will become contact wiring layer 83 in a later process, and silicon layer 585B, which will become gate electrode 63 in a later process.

[0125] 14D, a conductive impurity is implanted using a resist 594 having openings in regions corresponding to the silicon layer 585A and the silicon layer 585B as a mask. As a result, the conductive impurity is introduced into the silicon layer 585A and the silicon layer 585B, and the silicon layer 585A and the silicon layer 585B become conductive. As a result, the silicon layer 585B becomes the gate electrode 63.

[0126] 14E, a conductive impurity is implanted using a resist 595 having an opening in a region corresponding to the region where the silicon layer 585A is provided as a mask. As a result, the conductive impurity is introduced at a higher concentration into the silicon layer 585A, thereby forming the contact wiring layer 83.

[0127] Subsequently, as shown in FIG. 14F, a second insulating layer 522 and a light-shielding film 530 are sequentially formed on the contact wiring layer 83 and the gate electrode 63.

[0128] Then, as shown in FIG. 14G, a third insulating layer 523 is formed on the light-shielding film 530, and then etching is performed using a patterned resist 596 to form an opening 597 that penetrates the third insulating layer 523, the light-shielding film 530, and the second insulating layer 522 and exposes the contact wiring layer 83.

[0129] Furthermore, as shown in FIG. 14H, opening 597 is filled with a conductive material such as tungsten to form contact 73.

[0130] According to the above-described first forming method, the contact wiring layer 83 that is wired from the floating diffusion region 72 onto the element isolation layer 513 can be formed with a smaller number of steps.

[0131] (Second Forming Method) 15A to 15F, a second method for forming the contact wiring layer 83 shown in Fig. 12 will be described. Fig. 15A to 15F are vertical cross-sectional views illustrating each step of the second method for forming the contact wiring layer 83. The second method is a method in which the contact wiring layer 83 and the gate electrode 63 are formed separately and sequentially.

[0132] First, as shown in FIG. 15A, a first insulating layer 521 and a silicon layer 585 are sequentially formed on a semiconductor substrate 51 in which an element isolation layer 513 and a floating diffusion region 72 are provided.

[0133] Next, as shown in FIG. 15B, the silicon layer 585 is removed from the area other than the area corresponding to the gate electrode 63 by etching using a patterned resist 601.

[0134] 15C, after removing the resist 601, an insulating layer is formed on the semiconductor substrate 51 and the gate electrode 63. As a result, a first insulating layer 521 is provided on the semiconductor substrate 51, and a second insulating layer 522 is provided on the gate electrode 63.

[0135] Next, as shown in FIG. 15D, an opening 603 for forming a plug 580 is formed in the first insulating layer 521 by etching using a patterned resist.

[0136] 15E, a silicon layer 605 is formed on the first insulating layer 521 and the second insulating layer 522. As a result, the opening 603 formed in the first insulating layer 521 is filled with silicon, and a plug 580 is formed.

[0137] Thereafter, as shown in Fig. 15F, the silicon layer 605 is removed by etching using a patterned resist 606 except for the region corresponding to the contact wiring layer 83. As a result, a layer made of polysilicon can be formed in the region corresponding to the contact wiring layer 83 and the gate electrode 63, similar to the process shown in Fig. 14C. Therefore, after removing the second insulating layer 522 provided on the gate electrode 63, the contact wiring layer 83 wired from the floating diffusion region 72 onto the element isolation layer 513 can be formed through the same processes as those shown in Figs. 14D to 14H.

[0138] According to the above-described second forming method, the contact wiring layer 83 and the gate electrode 63 can be formed under process conditions suited to each of them.

[0139] (3.4. Modifications) Next, modified examples of the imaging device according to this embodiment will be described with reference to Fig. 16 to Fig. 18. The technology according to this embodiment can be applied to devices other than the imaging device having the pixel 2 as shown in Fig. 11. Fig. 16 to Fig. 18 are longitudinal sectional views showing an example of an imaging device to which the technology according to this embodiment can be applied.

[0140] For example, the technology according to the present embodiment can be applied to a back-illuminated imaging device as shown in Fig. 16 and Fig. 17. Fig. 16 and Fig. 17 are longitudinal sectional views that typically show the configuration of a back-illuminated imaging device.

[0141] As shown in Figures 16 and 17, in a back-illuminated imaging device, a second conductivity type (e.g., n-type) region 770A is provided inside a first conductivity type (e.g., p-type) silicon substrate 710, and a first conductivity type (e.g., p-type) region 770B is provided in the region on the side where the multilayer wiring layer 723 is provided, thereby forming a photoelectric conversion unit 770 which is a photodiode.

[0142] On the light receiving surface side (also referred to as the back surface side) of the silicon substrate 710, a pixel defining film 733 that defines pixels, a color filter 744, and an on-chip lens 745 are provided with insulating layers 741 and 743 interposed therebetween.

[0143] Moreover, a transfer gate 761 that extracts accumulated charges from the photoelectric conversion unit 770 is provided on the side opposite to the light-receiving surface side (also referred to as the front side) of the silicon substrate 710. The charges extracted from the photoelectric conversion unit 770 by the transfer gate 761 are accumulated in a floating diffusion region 711 provided on the front side of the silicon substrate 710. Furthermore, a light-shielding film 730 is provided on the multilayer wiring layer 723 provided on the side opposite to the light-receiving surface side of the silicon substrate 710 to shield reflected light from wiring layers 777 and the like included in the multilayer wiring layer 723.

[0144] A contact 773 electrically connected to the floating diffusion region 711 via a contact wiring layer 783 is provided on the element isolation layer 713. Note that the charge extracted from the floating diffusion region 711 by the contact wiring layer 783 and the contact 773 is outputted to a readout circuit (not shown) that converts the charge into a pixel signal via a wiring layer 777 or the like.

[0145] 16, an opening may be formed in the light-shielding film 730 from the viewpoint of layout or processing. Also, as shown in FIG. 17, an opening may be formed in the light-shielding film 730 in order to pass a contact, such as a well contact 779, which is electrically connected to the silicon substrate 710. According to the technology of this embodiment, it is possible to prevent light passing through such an opening in the light-shielding film 730 from being reflected by the wiring layer 777 and entering the floating diffusion region 711 from the multilayer wiring layer 723 side.

[0146] Furthermore, the technology according to the present embodiment can also be applied to an imaging device that realizes a back-illuminated global shutter operation, as shown in Fig. 18. Fig. 18 is a vertical cross-sectional view that illustrates a schematic configuration of an imaging device that realizes a back-illuminated global shutter operation.

[0147] 18, in an imaging device that realizes a back-illuminated global shutter operation, a charge holding unit 732 consisting of a first conductivity type region 732A and a second conductivity type region 732B is provided instead of the floating diffusion region 711 in the back-illuminated imaging device shown in Fig. 16 and Fig. 17. In addition, a light-shielding structure 734 made of tungsten or the like is provided on the light-receiving surface side of the charge holding unit 732 so as to cover the charge holding unit 732 in order to block direct incidence of light on the charge holding unit 732.

[0148] 18, even in an imaging device that realizes a back-illuminated global shutter operation, light that has passed through the photoelectric conversion unit 770 may further pass through the opening in the light-shielding film 730 and enter the silicon substrate 710 from the multilayer wiring layer 723 side. According to the technology of this embodiment, light that has passed through the opening in the light-shielding film 730 and entered the multilayer wiring layer 723 is reflected by the wiring layer 777, and thus can be prevented from entering the charge retention unit 732.

[0149] <4. Application Examples> Hereinafter, application examples of the imaging device according to the first or second embodiment of the present disclosure will be described with reference to FIGS.

[0150] (Application to imaging systems) First, an application example of the imaging device according to the first or second embodiment of the present disclosure to an imaging system will be described with reference to Fig. 19 and Fig. 20. Fig. 19 is a block diagram showing an example of a schematic configuration of an imaging system 900 including the imaging device 1 according to the first or second embodiment of the present disclosure. Fig. 20 shows an example of a flowchart of an imaging operation in the imaging system 900.

[0151] As shown in FIG. 19, an imaging system 900 is, for example, an imaging device such as a digital still camera or a video camera, or an electronic device such as a mobile terminal device such as a smartphone or a tablet terminal.

[0152] The imaging system 900 includes, for example, a lens group 941, a shutter 942, the imaging device 1 according to the first or second embodiment of the present disclosure, a DSP circuit 943, a frame memory 944, a display unit 945, a storage unit 946, an operation unit 947, and a power supply unit 948. In the imaging system 900, the imaging device 1, the DSP circuit 943, the frame memory 944, the display unit 945, the storage unit 946, the operation unit 947, and the power supply unit 948 are connected to each other via a bus line 949.

[0153] The imaging device 1 outputs image data according to the incident light that has passed through the lens group 941 and the shutter 942. The DSP circuit 943 is a signal processing circuit, and processes the signal (i.e., image data) output from the imaging device 1. The frame memory 944 temporarily holds the image data processed by the DSP circuit 943 on a frame-by-frame basis. The display unit 945 is a panel-type display device such as a liquid crystal panel or an organic EL (Electro Luminescence) panel, and displays a moving image or a still image captured by the imaging device 1. The storage unit 946 includes a recording medium such as a semiconductor memory or a hard disk, and records image data of the moving image or the still image captured by the imaging device 1. The operation unit 947 outputs operation commands for various functions of the imaging system 900 based on an operation by a user. The power supply unit 948 is a variety of power supplies that supply operating power to the imaging device 1, the DSP circuit 943, the frame memory 944, the display unit 945, the storage unit 946, and the operation unit 947.

[0154] Next, the imaging procedure in the imaging system 900 will be described.

[0155] 20, a user issues an instruction to start imaging by operating the operation unit 947 (S101). In response to this, the operation unit 947 transmits an imaging command to the imaging device 1 (S102). Upon receiving the imaging command, the imaging device 1 executes imaging in a predetermined imaging method (S103).

[0156] Thereafter, the imaging device 1 outputs the captured image data to the DSP circuit 943. The DSP circuit 943 performs predetermined signal processing (e.g., noise reduction processing, etc.) on the image data output from the imaging device 1 (S104). The DSP circuit 943 stores the image data that has been subjected to the predetermined signal processing in the frame memory 944. Thereafter, the frame memory 944 stores the image data in the storage unit 946 (S105). In this manner, imaging is performed in the imaging system 900.

[0157] In this application example, the imaging device 1 according to the first or second embodiment of the present disclosure is applied to an imaging system 900. According to the technology of the present disclosure, it is possible to further suppress noise due to reflected light inside the imaging device 1 or crosstalk between adjacent pixels 2. Therefore, according to the technology of the present disclosure, the imaging system 900 can capture images with higher image quality.

[0158] (Application to mobile control systems) The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of moving body such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility device, an airplane, a drone, a ship, a robot, etc.

[0159] FIG. 21 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a moving object control system to which the technology according to the present disclosure can be applied.

[0160] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 21, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also, as functional configurations of the integrated control unit 12050, a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053 are illustrated.

[0161] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0162] The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as head lamps, back lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves or signals of various switches transmitted from a portable device that replaces a key may be input to the body system control unit 12020. The body system control unit 12020 receives the input of these radio waves or signals and controls the door lock device, power window device, lamps, and the like of the vehicle.

[0163] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture an image outside the vehicle and receives the captured image. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for a person, a car, an obstacle, a sign, or characters on a road surface, based on the received image.

[0164] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal according to the amount of light received. The imaging unit 12031 can output the electrical signal as an image, or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0165] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing.

[0166] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, the steering mechanism, or the braking device based on the information inside and outside the vehicle acquired by the outside-of-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output a control command to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc.

[0167] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on the driver's operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle acquired by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0168] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside-vehicle information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside-vehicle information detection unit 12030, and perform cooperative control for the purpose of preventing glare, such as switching from high beams to low beams.

[0169] The audio / video output unit 12052 transmits at least one output signal of audio and video to an output device capable of visually or audibly notifying information to passengers in the vehicle or the outside of the vehicle. In the example of Fig. 15, an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are exemplified as the output device. The display unit 12062 may include at least one of an on-board display and a head-up display, for example.

[0170] FIG. 22 is a diagram showing an example of the installation position of the imaging unit 12031.

[0171] In FIG. 22, a vehicle 12100 has imaging units 12101, 12102, 12103, 12104, and 12105 as an imaging unit 12031.

[0172] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided at positions such as the front nose, side mirrors, rear bumper, back door, and the upper part of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided at the front nose and the imaging unit 12105 provided at the upper part of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided at the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided at the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The images of the front acquired by the imaging units 12101 and 12105 are mainly used to detect a preceding vehicle, a pedestrian, an obstacle, a traffic light, a traffic sign, a lane, or the like.

[0173] 22 shows an example of the imaging ranges of the imaging units 12101 to 12104. An imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and an imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, an overhead image of the vehicle 12100 viewed from above is obtained by superimposing the image data captured by the imaging units 12101 to 12104.

[0174] At least one of the imaging units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera made up of a plurality of imaging elements, or may be an imaging element having pixels for detecting a phase difference.

[0175] For example, the microcomputer 12051 can extract, as a preceding vehicle, a three-dimensional object that is the closest three-dimensional object on the travel path of the vehicle 12100 and travels at a predetermined speed (for example, 0 km / h or more) in approximately the same direction as the vehicle 12100, by calculating the distance to each three-dimensional object in the imaging ranges 12111 to 12114 and the change over time of this distance (relative speed with respect to the vehicle 12100) based on the distance information obtained from the imaging units 12101 to 12104. Furthermore, the microcomputer 12051 can set a vehicle distance to be secured in advance in front of the preceding vehicle, and perform automatic brake control (including follow-up stop control) and automatic acceleration control (including follow-up start control). In this way, cooperative control can be performed for the purpose of automatic driving that travels autonomously without relying on the driver's operation.

[0176] For example, the microcomputer 12051 classifies and extracts three-dimensional object data on three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. Then, the microcomputer 12051 determines a collision risk indicating the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0177] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether or not a pedestrian is present in the captured images of the imaging units 12101 to 12104. The recognition of such a pedestrian is performed, for example, by a procedure of extracting feature points in the captured images of the imaging units 12101 to 12104 as infrared cameras, and a procedure of performing pattern matching processing on a series of feature points that indicate the contour of an object to determine whether or not the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the captured images of the imaging units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular contour line for emphasis on the recognized pedestrian. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating a pedestrian at a desired position.

[0178] An example of a mobile object control system to which the technology according to the present disclosure can be applied has been described above. The technology according to the present disclosure can be applied to the imaging unit 12031 in the configuration described above. According to the technology according to the present disclosure, a captured image with higher image quality can be obtained, and therefore, a mobile object control system can perform high-precision control using the captured image.

[0179] (Application to endoscopic surgery systems) FIG. 23 is a diagram showing an example of a schematic configuration of an endoscopic surgery system to which the technology according to the present disclosure (the present technology) can be applied.

[0180] 23 shows a state in which an operator (doctor) 11131 is performing surgery on a patient 11132 on a patient bed 11133 using an endoscopic surgery system 11000. As shown in the figure, the endoscopic surgery system 11000 is composed of an endoscope 11100, other surgical tools 11110 such as an insufflation tube 11111 and an energy treatment tool 11112, a support arm device 11120 that supports the endoscope 11100, and a cart 11200 on which various devices for endoscopic surgery are mounted.

[0181] The endoscope 11100 is composed of a lens barrel 11101, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 11132, and a camera head 11102 connected to the base end of the lens barrel 11101. In the illustrated example, the endoscope 11100 is configured as a so-called rigid scope having a rigid lens barrel 11101, but the endoscope 11100 may be configured as a so-called flexible scope having a flexible lens barrel.

[0182] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 11101. A light source device 11203 is connected to the endoscope 11100, and light generated by the light source device 11203 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 11101, and is irradiated via the objective lens toward an observation target in the body cavity of the patient 11132. The endoscope 11100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0183] An optical system and an image sensor are provided inside the camera head 11102, and reflected light (observation light) from an observation target is collected on the image sensor by the optical system. The observation light is photoelectrically converted by the image sensor to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to an observation image. The image signal is transmitted to a camera control unit (CCU) 11201 as RAW data.

[0184] The CCU 11201 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and performs overall control of the operations of the endoscope 11100 and the display device 11202. Furthermore, the CCU 11201 receives an image signal from the camera head 11102, and performs various types of image processing on the image signal, such as development processing (demosaic processing), for displaying an image based on the image signal.

[0185] Under the control of the CCU 11201, the display device 11202 displays an image based on an image signal that has been subjected to image processing by the CCU 11201.

[0186] The light source device 11203 is composed of a light source such as an LED (Light Emitting Diode), and supplies the endoscope 11100 with irradiation light when photographing an operation site or the like.

[0187] The input device 11204 is an input interface for the endoscopic surgery system 11000. A user can input various information and instructions to the endoscopic surgery system 11000 via the input device 11204. For example, the user inputs an instruction to change the imaging conditions (type of irradiated light, magnification, focal length, etc.) of the endoscope 11100.

[0188] The treatment tool control device 11205 controls the driving of the energy treatment tool 11112 for cauterizing tissue, incising, sealing blood vessels, etc. The insufflation device 11206 sends gas into the body cavity of the patient 11132 via the insufflation tube 11111 to inflate the body cavity for the purpose of securing the field of view of the endoscope 11100 and securing the working space of the surgeon. The recorder 11207 is a device capable of recording various information related to the surgery. The printer 11208 is a device capable of printing various information related to the surgery in various formats such as text, image, or graph.

[0189] The light source device 11203 that supplies irradiation light to the endoscope 11100 when photographing the surgical site can be composed of a white light source composed of, for example, an LED, a laser light source, or a combination of these. When the white light source is composed of a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, so that the white balance of the captured image can be adjusted in the light source device 11203. In this case, it is also possible to capture images corresponding to each of the RGB colors in a time-division manner by irradiating the observation object with laser light from each of the RGB laser light sources in a time-division manner and controlling the driving of the image sensor of the camera head 11102 in synchronization with the irradiation timing. According to this method, a color image can be obtained without providing a color filter to the image sensor.

[0190] The light source device 11203 may be controlled to change the intensity of the light it outputs at predetermined time intervals. The driving of the image sensor of the camera head 11102 may be controlled in synchronization with the timing of the change in the light intensity to obtain images in a time-division manner, and the images may be synthesized to generate an image with a high dynamic range that is free of so-called blackout and whiteout.

[0191] The light source device 11203 may be configured to supply light of a predetermined wavelength band corresponding to the special light observation. In the special light observation, for example, by utilizing the wavelength dependency of light absorption in body tissue, a narrow band light is irradiated compared to the irradiated light (i.e., white light) during normal observation, and a predetermined tissue such as blood vessels on the mucous membrane surface is photographed with high contrast, so-called narrow band imaging is performed. Alternatively, in the special light observation, a fluorescent observation may be performed in which an image is obtained by fluorescence generated by irradiating an excitation light. In the fluorescent observation, it is possible to irradiate an excitation light to a body tissue and observe the fluorescence from the body tissue (autofluorescence observation), or to locally inject a reagent such as indocyanine green (ICG) into the body tissue and irradiate the body tissue with excitation light corresponding to the fluorescent wavelength of the reagent to obtain a fluorescent image. The light source device 11203 may be configured to supply narrow band light and / or excitation light corresponding to such special light observation.

[0192] FIG. 24 is a block diagram showing an example of the functional configuration of the camera head 11102 and the CCU 11201 shown in FIG.

[0193] The camera head 11102 has a lens unit 11401, an imaging unit 11402, a drive unit 11403, a communication unit 11404, and a camera head control unit 11405. The CCU 11201 has a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera head 11102 and the CCU 11201 are connected to each other by a transmission cable 11400 so as to be able to communicate with each other.

[0194] The lens unit 11401 is an optical system provided at the connection portion with the lens barrel 11101. Observation light taken in from the tip of the lens barrel 11101 is guided to the camera head 11102 and enters the lens unit 11401. The lens unit 11401 is configured by combining a plurality of lenses including a zoom lens and a focus lens.

[0195] The imaging unit 11402 is composed of an imaging element. The imaging element constituting the imaging unit 11402 may be one (so-called single-plate type) or multiple (so-called multi-plate type). When the imaging unit 11402 is composed of a multi-plate type, for example, each imaging element may generate an image signal corresponding to each of RGB, and a color image may be obtained by combining the image signals. Alternatively, the imaging unit 11402 may be configured to have a pair of imaging elements for acquiring image signals for the right eye and the left eye corresponding to 3D (Dimensional) display. By performing 3D display, the surgeon 11131 can more accurately grasp the depth of the biological tissue in the surgical site. Note that when the imaging unit 11402 is composed of a multi-plate type, multiple lens units 11401 may be provided corresponding to each imaging element.

[0196] Furthermore, the imaging unit 11402 does not necessarily have to be provided in the camera head 11102. For example, the imaging unit 11402 may be provided inside the lens barrel 11101, immediately behind the objective lens.

[0197] The driving unit 11403 is configured by an actuator, and moves the zoom lens and focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera head control unit 11405. This allows the magnification and focus of the image captured by the imaging unit 11402 to be appropriately adjusted.

[0198] The communication unit 11404 is configured by a communication device for transmitting and receiving various information to and from the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 to the CCU 11201 via the transmission cable 11400 as RAW data.

[0199] Furthermore, the communication unit 11404 receives a control signal for controlling the driving of the camera head 11102 from the CCU 11201, and supplies the control signal to the camera head control unit 11405. The control signal includes information on the imaging conditions, such as information specifying the frame rate of the captured image, information specifying the exposure value at the time of capturing the image, and / or information specifying the magnification and focus of the captured image.

[0200] The image capturing conditions such as the frame rate, exposure value, magnification, and focus may be appropriately specified by a user, or may be automatically set by the control unit 11413 of the CCU 11201 based on an acquired image signal. In the latter case, the endoscope 11100 is equipped with a so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function.

[0201] The camera head control unit 11405 controls the driving of the camera head 11102 based on a control signal received from the CCU 11201 via the communication unit 11404.

[0202] The communication unit 11411 is configured with a communication device for transmitting and receiving various information to and from the camera head 11102. The communication unit 11411 receives an image signal transmitted from the camera head 11102 via the transmission cable 11400.

[0203] Furthermore, the communication unit 11411 transmits, to the camera head 11102, a control signal for controlling the driving of the camera head 11102. The image signal and the control signal can be transmitted by electrical communication, optical communication, or the like.

[0204] The image processing unit 11412 performs various types of image processing on the image signal, which is RAW data sent from the camera head 11102 .

[0205] The control unit 11413 performs various controls related to imaging of the surgical site etc. by the endoscope 11100 and display of the captured image obtained by imaging the surgical site etc. For example, the control unit 11413 generates a control signal for controlling the driving of the camera head 11102.

[0206] Further, the control unit 11413 causes the display device 11202 to display the captured image showing the surgical site, etc., based on the image signal that has been image-processed by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition techniques. For example, the control unit 11413 can recognize surgical tools such as forceps, specific living body parts, bleeding, mist when the energy treatment tool 11112 is used, etc., by detecting the shape and color of the edge of an object included in the captured image. When the control unit 11413 causes the display device 11202 to display the captured image, it may use the recognition result to superimpose various types of surgery support information on the image of the surgical site. By superimposing and presenting the surgery support information to the surgeon 11131, the burden on the surgeon 11131 can be reduced and the surgeon 11131 can proceed with the surgery reliably.

[0207] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable for communication of electrical signals, an optical fiber for optical communication, or a composite cable of these.

[0208] Here, in the illustrated example, communication is performed wired using a transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may also be performed wirelessly.

[0209] An example of an endoscopic surgery system to which the technology according to the present disclosure can be applied has been described above. The technology according to the present disclosure can be suitably applied to the imaging unit 11402 provided in the camera head 11102 of the endoscope 11100 among the configurations described above. According to the technology according to the present disclosure, the image quality of the image captured by the imaging unit 11402 can be further improved, and therefore the visibility and operability of the user who uses the endoscopic surgery system can be improved.

[0210] The technology according to the present disclosure has been described above by giving the first and second embodiments and the modified examples. However, the technology according to the present disclosure is not limited to the above-mentioned embodiments, and various modifications are possible.

[0211] Moreover, the above first and second embodiments and the modified examples can be combined with each other.

[0212] Furthermore, not all of the configurations and operations described in each embodiment are necessarily essential to the configurations and operations of the present disclosure. For example, among the components in each embodiment, components that are not described in an independent claim showing the highest concept of the present disclosure should be understood as optional components.

[0213] Terms used throughout this specification and the appended claims should be construed as "open-ended" terms. For example, the terms "including" or "including" should be construed as "not limited to what is described as including." The term "having" should be construed as "not limited to what is described as having."

[0214] The terms used in this specification are merely used for convenience of explanation and do not limit the configuration and operation. For example, terms such as "right", "left", "upper", and "lower" merely indicate directions on the drawings to which reference is made. Furthermore, the terms "inner" and "outer" indicate directions toward and away from the center of the focused element, respectively. The same applies to terms similar to these and terms of a similar meaning.

[0215] The technology according to the present disclosure may also have the following configuration. According to the technology according to the present disclosure having the following configuration, it is possible to further suppress reflected light inside the imaging device from entering a photoelectric conversion unit, a charge holding unit, a floating diffusion region, or the like. Therefore, an imaging device to which the technology according to the present disclosure is applied can further suppress the occurrence of noise in pixel signals. The effects achieved by the technology according to the present disclosure are not necessarily limited to the effects described herein, and may be any of the effects described in the present disclosure. (1) a semiconductor substrate provided with a photoelectric conversion unit that converts incident light into an electric charge, a charge retention unit that accumulates electric charge photoelectrically converted by the photoelectric conversion unit, and a readout circuit that reads out the electric charge; a first light-shielding layer provided on one main surface of the semiconductor substrate; a contact extending through the first light-shielding layer in a normal direction to one major surface of the semiconductor substrate; a contact wiring layer that electrically connects the contact to a source or a drain of a field effect transistor provided on the semiconductor substrate; Equipped with a main surface of the semiconductor substrate includes a charge accumulation region including at least the photoelectric conversion portion and the charge retention portion, and a non-charge accumulation region including the readout circuit; The contact wiring layer extends to the non-charge accumulation region and is electrically connected to the contact in the non-charge accumulation region. (2) an element isolation layer is further provided in the semiconductor substrate in the non-charge storage region; The imaging device according to (1) above, wherein the contact wiring layer is electrically connected to the contact on the element isolation layer. (3) The imaging device according to (1) or (2) above, wherein the first light-shielding layer is provided in a region of one main surface of the semiconductor substrate excluding a region corresponding to the photoelectric conversion unit. (4) The imaging device according to any one of (1) to (3) above, wherein the contact wiring layer is made of polysilicon containing a conductive impurity. (5) The imaging device according to any one of (1) to (4) above, wherein a silicide layer is further provided on the contact wiring layer in a connection portion with the contact. (6) The imaging device according to any one of (1) to (5) above, wherein the incident light is incident on the photoelectric conversion section from a side on which the first light-shielding layer is provided. (7) The imaging device according to any one of (1) to (6) above, wherein the incident light is incident on the photoelectric conversion section from a side opposite to a side on which the first light-shielding layer is provided. (8) The imaging device according to any one of (1) to (7) above, wherein the field effect transistor is a field effect transistor that controls transfer of charges from the photoelectric conversion section or the charge holding section. (9) A plurality of pixels each including the photoelectric conversion unit are arranged on the semiconductor substrate, The imaging device according to any one of (1) to (8) above, wherein the field effect transistor is a field effect transistor provided between the pixels spaced apart from each other. (10) a second light-shielding layer provided on a surface side of the semiconductor substrate opposite to the one principal surface and having openings in a region corresponding to a light-receiving portion of the photoelectric conversion portion and in a region where the contact is provided; The imaging device according to any one of (1) to (9) above. (11) The opening of the second light-shielding layer is provided in the non-charge-accumulation region. The imaging device according to (10) above. [Explanation of symbols]

[0216] 1...imaging device, 2...pixel, 3...pixel array section, 4...vertical drive circuit, 5...column signal processing circuit, 6...horizontal drive circuit, 7...output circuit, 8...control circuit, 10...pixel drive wiring, 11...horizontal signal line, 20...multilayer wiring layer, 21...wiring layer, 22...interlayer insulating layer, 23, 26...contact plug, 24...wiring light shielding film, 24A...opening, 25...gate electrode, 27...extension, 30...semiconductor substrate, 31...photoelectric conversion section, 32...charge retention section, 33...light shielding structure, 33A...first light shielding film, 33B...second Light-shielding film, 33C... third light-shielding film, 34... floating diffusion region, 41... interlayer insulating layer, 42... secondary on-chip lens, 43... planarizing film, 44... color filter layer, 45... primary on-chip lens, 46... pixel separation structure, 46A... pixel insulating film, 46B... pixel definition film, 51... semiconductor substrate, 61, 62, 63, 64, 65, 66... ​​gate electrode, 70... photoelectric conversion section, 71... charge retention section, 72... floating diffusion region, 73, 74, 75, 77... contact, 76... charge discharge section, 83, 84, 85, 86 contact wiring layer

Claims

1. a semiconductor substrate provided with a photoelectric conversion unit that converts incident light into an electric charge, a charge retention unit that accumulates electric charge photoelectrically converted by the photoelectric conversion unit, and a readout circuit that reads out the electric charge; a first light-shielding layer provided on one main surface of the semiconductor substrate; a contact extending through the first light-shielding layer in a normal direction to one major surface of the semiconductor substrate; a contact wiring layer that electrically connects the contact to a source or a drain of a field effect transistor provided on the semiconductor substrate; Equipped with a main surface of the semiconductor substrate includes a charge accumulation region including at least the photoelectric conversion portion and the charge retention portion, and a non-charge accumulation region including the readout circuit; The contact wiring layer extends to the non-charge accumulation region and is electrically connected to the contact in the non-charge accumulation region.

2. an element isolation layer is further provided in the semiconductor substrate in the non-charge storage region; The imaging device according to claim 1 , wherein the contact wiring layer is electrically connected to the contact on the element isolation layer.

3. The imaging device according to claim 1 , wherein the first light-shielding layer is provided in a region of the one main surface of the semiconductor substrate excluding a region corresponding to the photoelectric conversion unit.

4. The imaging device according to claim 1 , wherein the contact wiring layer is made of polysilicon containing a conductive impurity.

5. The imaging device according to claim 4 , wherein a silicide layer is further provided on the contact wiring layer in a portion connected to the contact.

6. The imaging device according to claim 1 , wherein the incident light is incident on the photoelectric conversion section from a side on which the first light-shielding layer is provided.

7. The imaging device according to claim 1 , wherein the incident light is incident on the photoelectric conversion unit from a side opposite to a side on which the first light-shielding layer is provided.

8. The imaging device according to claim 1 , wherein the field effect transistor is a field effect transistor that controls transfer of charges from the photoelectric conversion unit or the charge storage unit.

9. A plurality of pixels each including the photoelectric conversion unit are arranged on the semiconductor substrate, The imaging device according to claim 1 , wherein the field effect transistor is provided between the pixels spaced apart from each other.

10. a second light-shielding layer provided on a surface side opposite to the one principal surface of the semiconductor substrate and having openings in a region corresponding to a light-receiving portion of the photoelectric conversion portion and in a region where the contact is provided; The imaging device according to claim 1 .

11. The opening of the second light-shielding layer is provided in the non-charge-accumulation region. The imaging device according to claim 10.

Images