Photoelectric conversion device and photoelectric conversion system

Abstract

To provide a photoelectric conversion device with improved noise characteristics.SOLUTION: A photoelectric conversion device includes a first component that includes a first semiconductor substrate having a first surface and a second surface opposite to the first surface, a photoelectric conversion part provided on the first semiconductor substrate, a floating diffusion part and a transfer gate. The first component includes a first buried electrode connected to the photoelectric conversion part and a second buried electrode connected to the floating diffusion part. The depth from the first surface to the end on the second surface side of the first buried electrode is different from the depth from the first surface to the end on the second surface side of the second buried electrode.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a photoelectric conversion device and a photoelectric conversion system. [Background technology]

[0002] Patent Document 1 describes that miniaturization of pixels can be achieved by providing a photoelectric conversion section in a first semiconductor layer, a pixel circuit in a second semiconductor layer, and forming a contact electrode with an embedded structure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 138914 Summary of the Invention [Problem to be solved by the invention]

[0004] However, Patent Document 1 does not consider suppressing noise that may occur in the contact electrodes with a buried structure. [Means for solving the problem]

[0005] One aspect of the present invention is a photoelectric conversion device comprising: a first semiconductor substrate having a first surface and a second surface opposite to the first surface; a first component having a photoelectric conversion unit provided on the first semiconductor substrate, a floating diffusion unit, and a transfer gate provided on the first surface side of the first semiconductor substrate and configured to transfer signal charges generated in the photoelectric conversion unit to the floating diffusion unit, wherein the first component comprises a first embedded electrode connected to the photoelectric conversion unit and a second embedded electrode connected to the floating diffusion unit, and wherein a depth from the first surface to an end of the first embedded electrode on the second surface side is different from a depth from the first surface to an end of the second embedded electrode on the second surface side. Effect of the Invention

[0006] According to the present invention, it is possible to provide a photoelectric conversion device with improved noise characteristics. [Brief description of the drawings]

[0007] [Figure 1] 1 is a block diagram showing a schematic configuration of a photoelectric conversion device according to a first embodiment. [Diagram 2] 1 is an equivalent circuit diagram of a pixel of the photoelectric conversion device according to the first embodiment. [Diagram 3] FIG. 2 is a plan view of a pixel of the photoelectric conversion device according to the first embodiment. [Figure 4] 1 is a cross-sectional view of a pixel of a photoelectric conversion device according to a first embodiment. [Diagram 5] FIG. 6 is a cross-sectional view of a pixel of a photoelectric conversion device according to a second embodiment. [Figure 6] FIG. 11 is a cross-sectional view of a pixel of a photoelectric conversion device according to a third embodiment. [Figure 7] FIG. 11 is a cross-sectional view of a pixel of a photoelectric conversion device according to a fourth embodiment. [Figure 8] FIG. 13 is a cross-sectional view of a pixel of a photoelectric conversion device according to a fifth embodiment. [Figure 9] FIG. 13 is a cross-sectional view of a pixel of a photoelectric conversion device according to a sixth embodiment. [Figure 10] FIG. 13 is a plan view of a pixel of a photoelectric conversion device according to a seventh embodiment. [Figure 11] FIG. 13 is a cross-sectional view of a pixel of a photoelectric conversion device according to a seventh embodiment. [Figure 12] FIG. 13 is a functional block diagram of a photoelectric conversion system according to an eighth embodiment. [Figure 13] FIG. 13 is a functional block diagram of a photoelectric conversion system according to a ninth embodiment. [Figure 14] FIG. 23 is a functional block diagram of a photoelectric conversion system according to a tenth embodiment. [Figure 15] FIG. 23 is a functional block diagram of a photoelectric conversion system according to an eleventh embodiment. [Figure 16]FIG. 23 is a functional block diagram of a photoelectric conversion system according to a twelfth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] (First embodiment) A photoelectric conversion device according to a first embodiment of the present invention will be described with reference to Figs. 1 to 4. Fig. 1 is a block diagram showing a schematic configuration of the photoelectric conversion device according to this embodiment. Fig. 2 is an equivalent circuit diagram of a pixel of the photoelectric conversion device according to this embodiment. Fig. 3 is a planar layout of a pixel of the photoelectric conversion device according to this embodiment. Fig. 4 is a diagram showing a cross section of a pixel of the photoelectric conversion device according to this embodiment.

[0009] The photoelectric conversion device 100 according to this embodiment includes a pixel region 10, a vertical scanning circuit 20, a column readout circuit 30, a horizontal scanning circuit 40, a control circuit 50, and an output circuit 60, as shown in FIG.

[0010] The pixel region 10 is provided with a plurality of pixels 12 arranged in a matrix across a plurality of rows and a plurality of columns. A control signal line 14 is arranged in each row of the pixel array of the pixel region 10, extending in the row direction (horizontal direction in FIG. 1). The control signal line 14 is connected to each of the pixels 12 arranged in the row direction, and serves as a common signal line for these pixels 12. Furthermore, a vertical output line 16 is arranged in each column of the pixel array of the pixel region 10, extending in the column direction (vertical direction in FIG. 1). The vertical output line 16 is connected to each of the pixels 12 arranged in the column direction, and serves as a common signal line for these pixels 12.

[0011] The control signal line 14 of each row is connected to a vertical scanning circuit 20. The vertical scanning circuit 20 is a circuit section that supplies the pixels 12 with control signals via the control signal line 14 to drive the readout circuits in the pixels 12 when reading out pixel signals from the pixels 12. One end of the vertical output line 16 of each column is connected to a column readout circuit 30. The pixel signals read out from the pixels 12 are input to the column readout circuit 30 via the vertical output line 16. The column readout circuit 30 is a circuit section that performs predetermined signal processing, such as amplification processing and AD conversion processing, on the pixel signals read out from the pixels 12. The column readout circuit 30 may include a differential amplifier circuit, a sample-and-hold circuit, an AD conversion circuit, and the like.

[0012] The horizontal scanning circuit 40 is a circuit section that supplies control signals to the column readout circuit 30 for sequentially transferring pixel signals processed in the column readout circuit 30 to the output circuit 60 for each column. The control circuit 50 is a circuit section that supplies control signals that control the operations and timings of the vertical scanning circuit 20, the column readout circuit 30, and the horizontal scanning circuit 40. The output circuit 60 is a circuit section that is composed of a buffer amplifier, a differential amplifier, etc., and outputs the pixel signals read out from the column readout circuit 30 to a signal processing section outside the photoelectric conversion device 100.

[0013] FIG. 2 shows an equivalent circuit diagram for four pixels. The floating diffusions (FDs) 121 of a plurality of photodiodes (PDs) 101, which are photoelectric conversion units, are electrically connected to each other and to the input terminal of a common pixel circuit 171. In FIG. 2, in order to distinguish the photoelectric conversion unit 101 corresponding to each pixel, suffixes from a to d are added to each reference character. By providing one pixel circuit 171 for a plurality of photoelectric conversion units 101 in this way, there is an advantage that the area occupied by the pixel circuit 171 in the entire photoelectric conversion device can be reduced. Here, a circuit configuration in which one FD is shared by four pixels is shown, but the number of pixels sharing the FD is not limited to four pixels, and it is sufficient that the FD is electrically connected to at least two or more pixels.

[0014] The photoelectric conversion unit 101 generates electric charges in response to incidence of light. The transfer transistor 111 is a transistor that transfers the electric charges generated in the photoelectric conversion unit 101.

[0015] The cathode of the photoelectric conversion unit 101 is electrically connected to the source of the transfer transistor 111, and the anode of the photoelectric conversion unit 101 is electrically connected to a reference potential line (e.g., ground). The drain of the transfer transistor 111 is electrically connected to the FD 121, and the gate of the transfer transistor 111 is electrically connected to a pixel drive line (not shown).

[0016] The charge output from the photoelectric conversion unit 101 via the transfer transistor 111 is temporarily held in the FD 121 .

[0017] The pixel circuit 171 includes, for example, a reset transistor 131, a selection transistor 151, and an amplification transistor 141.

[0018] The gate of the reset transistor 131 is electrically connected to a pixel drive line (not shown). The source of the amplification transistor 141 is electrically connected to the drain of the selection transistor 151, and the gate of the amplification transistor 141 is electrically connected to the source of the reset transistor 131. The source of the selection transistor 151 (the output terminal of the pixel circuit 171) is electrically connected to the output line 161, and the gate of the selection transistor 151 is electrically connected to the pixel drive line (not shown).

[0019] When the transfer transistor 111 is turned on, it transfers the charge of the PD 101 to the FD 121. The gate (transfer gate) of the transfer transistor 111 is disposed so as to be provided on the surface of the semiconductor layer. Alternatively, it may extend to a depth that reaches the photoelectric conversion unit 101 from the surface of the semiconductor layer. In other words, it may be in the form of a vertical transfer gate.

[0020] The reset transistor 131 resets to a predetermined potential the potential of the FD 121. When the reset transistor 131 is turned on, the potential of the FD 121 is reset to the potential of the power supply line VDD.

[0021] The selection transistor 151 controls the output timing of a pixel signal from the pixel circuit 171. The selection transistor 151 may be omitted if necessary. The source of the reset transistor 131 (the input terminal of the pixel circuit 171) is electrically connected to the FD 121, and the drain of the reset transistor 131 is electrically connected to the power supply line VDD and the drain of the amplification transistor 141.

[0022] The amplification transistor 141 generates, as a pixel signal, a signal having a voltage corresponding to the level of the charge held in the FD 121. The amplification transistor 141 constitutes a source follower type amplifier, and outputs a pixel signal having a voltage corresponding to the level of the charge generated in the photoelectric conversion unit 101. When the selection transistor 151 is turned on, the amplification transistor 141 amplifies the potential of the FD 121, and outputs a voltage corresponding to the potential to a column circuit (not shown) via an output line 161.

[0023] The selection transistor 151 may be provided between the power supply line VDD and the amplification transistor 141. In this case, the drain of the reset transistor 131 is electrically connected to the power supply line VDD and the drain of the selection transistor 151. The source of the selection transistor 151 is electrically connected to the drain of the amplification transistor 141, and the gate of the selection transistor 151 is electrically connected to a pixel drive line (not shown). The source of the amplification transistor 141 is electrically connected to the output line 161, and the gate of the amplification transistor 141 is electrically connected to the source of the reset transistor 131.

[0024] The dotted line in FIG. 2 indicates the boundary between the first component 310 and the second component 320. The PD 101, the transfer transistor 111, and the reset transistor 131 are disposed in the first component 310, and the amplification transistor 141 and the selection transistor 151 are disposed in the second component 320.

[0025] Fig. 3 shows a plan view of a first component 310 of a photoelectric conversion device according to this embodiment. Fig. 3 shows a planar structure corresponding to four PDs 101 sharing one FD 121.

[0026] The four PDs 101 are arranged in two rows and two columns, and the PDs 101 are separated from each other by lattice-shaped separation portions 201. An FD 121 shared by the four PDs 101 is provided at a position adjacent to all of the four PDs 101. In the photoelectric conversion device according to this embodiment, the FD 121 is provided at the center of the four PDs 101 arranged in two rows and two columns. The FD 121 has a first embedded electrode 221, and a first through electrode 231 is connected to the first embedded electrode 221. Furthermore, a gate of a transfer transistor 111 that transfers charges photoelectrically converted by the PD 101 to the FD 121 is arranged close to the FD 121. A through electrode 211 for supplying a voltage for controlling the driving of the transfer transistor is connected to the gate of the transfer transistor 111.

[0027] In each of the four PDs 101 , a second through electrode 251 is electrically connected to the semiconductor region 261 via a second embedded electrode 241 .

[0028] The through electrode 211 connected to the transfer gate 111, the first through electrode 231, and the second through electrode 251 each extend toward the second component 320 side.

[0029] Fig. 4 is a cross-sectional view taken along the line A-A' in Fig. 3. The photoelectric conversion device according to this embodiment has a structure in which a first component 310 and a second component 320 are stacked. The first component 310 has a first substrate 310a and a first wiring layer 310b, and the second component 320 has a second substrate 320a and a second wiring layer 320b. Fig. 4 shows a portion of the first component 310, the second substrate 320a, and the second wiring layer 320b.

[0030] The PD 101 and the transfer transistor 111 are disposed on the first substrate 310a. The separation section 201 separates the PDs 101 from each other, and the first embedded electrode 221 and the second embedded electrode 241 are disposed on the boundary between the PDs 101. The N-type semiconductor region 121 is disposed around the first embedded electrode 221, and the P-type semiconductor region 261 is disposed around the second embedded electrode 241. The P-type semiconductor region 281 is disposed along the separation section 201, and the P-type semiconductor region 291 is disposed on the light incident surface side of the first substrate 310a. A voltage is supplied to the semiconductor regions 281 and 291 from the second through electrode 251 via the semiconductor region 261. The semiconductor regions 281 and 291 form a PN junction with the N-type semiconductor region 271, and function as the PD 101. The gate of the transfer transistor 111 is provided between the FD 121 and the semiconductor region 271, and transfers the charge converted by the PD 101 to the FD 121. Around the transfer transistor 111, a semiconductor region 200 is provided.

[0031] The pixel circuit 171 is provided on the second substrate 320a. Further, a through hole is provided on the second substrate 320a, and a first through electrode 231 and a second through electrode 251 are arranged through the through hole. Each through electrode is made of, for example, tungsten, and an insulating film is provided between each through electrode and the second substrate 320a. As described above, the first through electrode 231 and the second through electrode 251 are connected to the first buried electrode 221 and the second buried electrode 241, respectively. Each buried electrode is made of, for example, polycrystalline silicon doped with impurities.

[0032] When the first embedded electrode 221 is not used and an electrode is provided on the surface of the first substrate 101a, it is necessary to connect the through electrode 231 to the first semiconductor substrate 310a of the pixel 101 to supply a voltage. Specifically, the through electrode 231 is connected to the semiconductor region 121. In this case, it is necessary to arrange the semiconductor region 121 with a relatively large area in order to reduce the occurrence of defects due to misalignment of the through electrode 231 during the manufacturing process. Therefore, when maintaining the pixel pitch, the area allocated to the PD 101 and the like in each pixel is reduced. By providing the first embedded electrode 221 as in the photoelectric conversion device according to this embodiment, a contact with low contact resistance can be formed in a smaller area, which is advantageous for miniaturization.

[0033] Moreover, the first embedded electrode 221 and the second embedded electrode 241 are configured to be embedded in a groove formed in the first semiconductor substrate 320a. As a result, the first embedded electrode 221 and the second embedded electrode 241 are shaped to be connected at the side to the first semiconductor substrate 320a adjacent to the groove 179. The connection surfaces between the first embedded electrode 221 and the second embedded electrode 241 and the first semiconductor substrate 320a are arranged in a direction perpendicular to the surface of the first semiconductor substrate 320a, and the connection resistance can be reduced. Therefore, the area occupied by the first embedded electrode 221 and the second embedded electrode 241 can be reduced, and the area occupied by the PD 101 can be expanded.

[0034] Here, the embedding depth of the embedded electrodes 221 and the like into the first semiconductor substrate 320a ("d2" in FIG. 4) is preferably 50 nm or more, because this makes it possible to widen the connection surface between the first embedded electrode 221 and the second embedded electrode 241 and the first semiconductor substrate 120, thereby reducing the connection resistance.

[0035] On the other hand, there is a concern that forming the first buried electrode 221 and the second buried electrode 241 deep in the first semiconductor substrate 320a may increase the dark current generated around the contacts.

[0036] In the photoelectric conversion device according to this embodiment, the depth (d2) from the surface (first surface) facing the light incident surface of the first semiconductor substrate 320a to the end of the first embedded electrode 221 on the light incident surface (second surface) side is deeper than the depth (d1) from the first surface to the end of the second embedded electrode 241 on the second surface side. With this configuration, it is possible to suppress the dark current generated around the second embedded electrode 241 while suppressing the contact resistance of the first embedded electrode 221. Note that in FIG. 3 and FIG. 4, the first embedded electrode 221 and the second embedded electrode 241 are drawn to have the same size in a plan view, but the size is not limited to this, and they may be different sizes from each other. In addition, it is not necessary to satisfy this configuration in all pixels in the pixel array of the pixel region 10, and a configuration in which the depths of the first embedded electrode 221 and the second embedded electrode 241 are different only in some pixels may be used.

[0037] Second embodiment A photoelectric conversion device according to a second embodiment will be described with reference to Fig. 5. The second embodiment is a modified example of the first embodiment. Descriptions common to the first embodiment will be omitted, and differences from the first embodiment will be mainly described.

[0038] When forming the second buried electrode 241 deep in the substrate, if the P-type semiconductor region 261 around the second buried electrode 241 is also formed deep, there is a concern that the volume of the PD 101 and the amount of saturation charge that can be stored may decrease. In the photoelectric conversion device shown in this embodiment, the P-type semiconductor region 261 around the second buried electrode 241 is formed shallower than the N-type semiconductor region 121 around the first buried electrode 221. In other words, compared with the surface (first surface) facing the light incident surface, the end of the N-type semiconductor region 121 on the light incident surface (second surface) side is closer to the second surface than the end of the P-type semiconductor region 261 on the second surface side. This provides an effect of suppressing the decrease in the amount of charge stored around the first buried electrode 221. In addition, the P-type semiconductor region 261 around the second buried electrode 241 may be formed smaller than the N-type semiconductor region 121 around the first buried electrode 221 in a plan view. This makes it possible to further suppress the decrease in the amount of charge stored around the first buried electrode 221.

[0039] Third embodiment A photoelectric conversion device according to a third embodiment will be described with reference to Fig. 6. A photoelectric conversion device according to a third embodiment will be described. Explanations common to the first embodiment will be omitted, and differences from the first embodiment will be mainly described.

[0040] In the photoelectric conversion device according to this embodiment, contrary to the photoelectric conversion device according to the first embodiment, the depth (d1) from the surface (first surface) facing the light incident surface of the first semiconductor substrate 320a to the end of the second embedded electrode 241 on the light incident surface (second surface) side is deeper than the depth (d2) from the first surface to the end of the first embedded electrode 221 on the second surface side. With this configuration, it is possible to suppress the dark current generated around the first embedded electrode 221 while suppressing the contact resistance of the second embedded electrode 241.

[0041] As in the first embodiment, the sizes of the first embedded electrode 221 and the second embedded electrode 241 in a planar view may be different, and the depths of the first embedded electrode 221 and the second embedded electrode 241 may be different only in some pixels.

[0042] (Fourth embodiment) A photoelectric conversion device according to a fourth embodiment will be described with reference to Fig. 7. The fourth embodiment is a modified example of the third embodiment. Explanations common to the third embodiment will be omitted, and differences from the third embodiment will be mainly described.

[0043] If the N-type semiconductor region 121 around the first embedded electrode 221 is formed deep in the substrate, the FD capacitance increases, reducing the gain during charge-to-voltage conversion, which may increase the ratio of circuit noise components to the signal output from the pixel and worsen the signal-to-noise ratio.

[0044] In this embodiment, the N-type semiconductor region 121 around the first embedded electrode 221 is formed shallower than the P-type semiconductor region 261 around the second embedded electrode 241. In other words, in comparison with the surface (first surface) facing the light incident surface, the end of the N-type semiconductor region 121 on the light incident surface (second surface) side is closer to the first surface than the end of the P-type semiconductor region 261 on the second surface side. With this configuration, it is possible to easily recombine dark currents generated in the first embedded electrode 221, while reducing the FD capacitance, thereby achieving a noise suppression effect.

[0045] As in the second embodiment, the sizes of the N-type semiconductor region 121 around the first embedded electrode 221 and the P-type semiconductor region 261 around the second embedded electrode 241 in a plan view may be made different from each other. This can provide a stronger noise suppression effect.

[0046] Fifth embodiment A photoelectric conversion device according to a fifth embodiment will be described with reference to FIG. 8. The fifth embodiment is a modified example of the first embodiment. Explanations common to the first embodiment will be omitted, and differences from the first embodiment will be mainly described. The gate of the transfer transistor 111 of the photoelectric conversion device according to this embodiment is a vertical transfer gate.

[0047] When a vertical transfer gate is used as the gate of the transfer transistor 111, the charge photoelectrically converted by the PD 101 moves vertically toward the surface (first surface) of the first semiconductor substrate 320a when it is transferred to the FD. At this time, there is a concern that some of the charge cannot be transferred to the FD within the transfer time, resulting in an afterimage.

[0048] The photoelectric conversion device according to this embodiment has a structure in which the N-type semiconductor region 121 around the first embedded electrode 221 is formed deep in the first semiconductor substrate 310a. This reduces the amount of vertical movement of charges when they move from the PD 101 to the FD 121, making it possible to transfer charges to the FD 121 in a shorter transfer time. This makes it possible to realize a photoelectric conversion device with improved afterimages.

[0049] Sixth embodiment A photoelectric conversion device according to the sixth embodiment will be described with reference to FIG. 9. The sixth embodiment is a modified example of the third embodiment. Explanations common to the third embodiment will be omitted, and differences from the first embodiment will be mainly described. The gate of the transfer transistor 111 of the photoelectric conversion device according to this embodiment is a vertical transfer gate.

[0050] When a vertical transfer gate is used as the gate of the transfer transistor 111, if the FD121 is formed deep in the first semiconductor substrate 310a, the distance to the PD101, which is also formed deep in the first semiconductor substrate 310a, becomes closer. When the distance between the PD101 and the FD becomes closer, the potential barrier against the signal charge between the PD101 and the FD121 becomes lower, and the charge accumulated in the PD101 becomes more likely to leak to the FD121. In addition, when the PD101 is saturated, a part of the charge accumulated in the PD101 overflows to the FD121. At this time, the lower the potential barrier between the PD101 and the FD121, the more the amount of overflow increases, so there is a concern that the saturated charge amount of the FD101 will decrease.

[0051] In the photoelectric conversion device according to this embodiment, the first buried electrode 221 is formed shallower than the second buried electrode 241, thereby making it possible to ensure the distance between the PD 101 and the FD 121 while reducing the contact resistance of the second buried electrode 241. This makes it possible to increase the saturation charge amount of the FD 121.

[0052] Seventh embodiment The photoelectric conversion device according to the seventh embodiment will be described with reference to Figures 10 and 11. Explanations common to the first embodiment will be omitted, and differences from the first embodiment will be mainly described. The photoelectric conversion device according to this embodiment differs from the photoelectric conversion device according to the first embodiment in that pixel circuits 171 are provided on a first substrate 310a.

[0053] Fig. 10 is a plan view of the first substrate 310a, and Fig. 11 is a cross-sectional view taken along line AA' of Fig. 10. Gates of transistors (e.g., the amplification transistor 141 and the transfer transistor 151) constituting the pixel circuit 171 and electrodes connected to the transistors are provided.

[0054] As in the first embodiment, the first embedded electrode 221 of the photoelectric conversion device according to this embodiment is provided deeper in the first substrate 310a than the second embedded electrode 241. This configuration provides the effect of suppressing dark current generated in the second embedded electrode 241. A configuration similar to that shown in the fourth embodiment may be applied to a photoelectric conversion device in which up to the pixel circuit 171 is provided on the same substrate as the PD 101. That is, the second embedded electrode 241 may be provided deeper in the first substrate 310a than the first embedded electrode 221. With such a configuration, a noise suppression effect can be expected.

[0055] In this way, even in a photoelectric conversion device in which up to the pixel circuit 171 is provided on the same substrate as the PD 101, the effect of the present invention can be obtained by making the depths of the first embedded electrode 221 and the second embedded electrode 241 different.

[0056] Eighth embodiment The photoelectric conversion system according to this embodiment will be described with reference to Fig. 12. Fig. 12 is a block diagram showing a schematic configuration of the photoelectric conversion system according to this embodiment.

[0057] The photoelectric conversion devices described in the first to eighth embodiments are applicable to various photoelectric conversion systems. Examples of the applicable photoelectric conversion systems include digital still cameras, digital camcorders, security cameras, copiers, fax machines, mobile phones, car-mounted cameras, and observation satellites. Camera modules equipped with an optical system such as a lens and an imaging device are also included in the photoelectric conversion systems. FIG. 16 illustrates a block diagram of a digital still camera as an example of these.

[0058] 12 includes an image pickup device 1004, which is an example of a photoelectric conversion device, and a lens 1002 that forms an optical image of a subject on the image pickup device 1004. The system further includes an aperture 1003 that varies the amount of light passing through the lens 1002, and a barrier 1001 that protects the lens 1002. The lens 1002 and the aperture 1003 form an optical system that focuses light on the image pickup device 1004. The image pickup device 1004 is a photoelectric conversion device according to any one of the above embodiments, and converts the optical image formed by the lens 1002 into an electrical signal.

[0059] The photoelectric conversion system also has a signal processing unit 1007 which is an image generating unit that generates an image by processing an output signal output from the imaging device 1004. The signal processing unit 1007 performs various corrections and compression as necessary to output image data. The signal processing unit 1007 may be formed on the semiconductor substrate on which the imaging device 1004 is provided, or may be formed on a semiconductor substrate separate from the imaging device 1004.

[0060] The photoelectric conversion system further includes a memory unit 1010 for temporarily storing image data, and an external interface unit (external I / F unit) 1013 for communicating with an external computer or the like. The photoelectric conversion system further includes a recording medium 1012 such as a semiconductor memory for recording or reading out imaging data, and a recording medium control interface unit (recording medium control I / F unit) 1011 for recording or reading out data on the recording medium 1012. The recording medium 1012 may be built into the photoelectric conversion system, or may be removable.

[0061] The photoelectric conversion system further includes an overall control / calculation unit 1009 that performs various calculations and controls the entire digital still camera, and a timing generation unit 1008 that outputs various timing signals to the image capture device 1004 and the signal processing unit 1007. Here, the timing signals and the like may be input from outside, and the photoelectric conversion system only needs to include at least the image capture device 1004 and the signal processing unit 1007 that processes the output signal output from the image capture device 1004.

[0062] The imaging device 1004 outputs an imaging signal to a signal processing unit 1007. The signal processing unit 1007 performs predetermined signal processing on the imaging signal output from the imaging device 1004, and outputs image data. The signal processing unit 1007 generates an image using the imaging signal.

[0063] In this way, according to this embodiment, it is possible to realize a photoelectric conversion system to which the photoelectric conversion device (imaging device) according to any one of the above embodiments is applied.

[0064] Ninth embodiment The photoelectric conversion system and the moving object of this embodiment will be described with reference to Fig. 13. Fig. 13 is a diagram showing the configuration of the photoelectric conversion system and the moving object of this embodiment.

[0065] FIG. 13(a) shows an example of a photoelectric conversion system related to an in-vehicle camera. The photoelectric conversion system 1300 has an imaging device 1310. The imaging device 1310 is the photoelectric conversion device described in any of the above embodiments. The photoelectric conversion system 1300 has an image processing unit 1312 that performs image processing on a plurality of image data acquired by the imaging device 1310, and a parallax acquisition unit 1314 that calculates parallax (phase difference of parallax images) from the plurality of image data acquired by the photoelectric conversion system 1300. The photoelectric conversion system 1300 also has a distance acquisition unit 1316 that calculates a distance to an object based on the calculated parallax, and a collision determination unit 1318 that determines whether or not there is a possibility of collision based on the calculated distance. Here, the parallax acquisition unit 1314 and the distance acquisition unit 1316 are examples of distance information acquisition means that acquire distance information to an object. That is, the distance information is information on the parallax, the defocus amount, the distance to the object, and the like. The collision determination unit 1318 may determine the possibility of a collision using any of these distance information. The distance information acquisition means may be realized by dedicated hardware or a software module. Also, it may be realized by an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or the like, or may be realized by a combination of these. The photoelectric conversion system 1300 is connected to a vehicle information acquisition device 1320, and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. In addition, the photoelectric conversion system 1300 is connected to a control ECU 1330, which is a control unit that outputs a control signal for generating a braking force for the vehicle based on the determination result of the collision determination unit 1318. In addition, the photoelectric conversion system 1300 is also connected to an alarm device 1340 that issues an alarm to the driver based on the determination result of the collision determination unit 1318. For example, if the collision determination unit 1318 determines that there is a high possibility of a collision, the control ECU 1330 applies the brakes, releases the accelerator, suppresses engine output, or performs other vehicle control to avoid a collision and reduce damage.The alarm device 1340 warns the user by sounding an alarm, displaying alarm information on the screen of a car navigation system or the like, vibrating the seat belt or steering wheel, or the like.

[0066] In this embodiment, the surroundings of the vehicle, for example, the front or rear, are imaged by the photoelectric conversion system 1300. Fig. 13(b) shows the photoelectric conversion system when imaging the area in front of the vehicle (imaging range 1350). A vehicle information acquisition device 1320 sends instructions to the photoelectric conversion system 1300 or the imaging device 1310. This configuration can further improve the accuracy of distance measurement.

[0067] Although the above describes an example of control to prevent collision with other vehicles, the present invention can also be applied to control of automatic driving by following other vehicles, control of automatic driving to prevent deviation from lanes, etc. Furthermore, the photoelectric conversion system is not limited to vehicles such as the vehicle itself, but can be applied to moving bodies (moving devices) such as ships, aircraft, and industrial robots. In addition, the present invention can be applied not only to moving bodies, but also to a wide range of devices that use object recognition, such as intelligent transport systems (ITS).

[0068] (Tenth embodiment) The photoelectric conversion system of this embodiment will be described with reference to Fig. 14. Fig. 14 is a block diagram showing an example of the configuration of a range image sensor which is the photoelectric conversion system of this embodiment.

[0069] 14, the distance image sensor 401 is configured to include an optical system 407, a photoelectric conversion device 408, an image processing circuit 404, a monitor 405, and a memory 406. The distance image sensor 401 can obtain a distance image according to the distance to the subject by receiving light (modulated light or pulsed light) that is projected from a light source device 409 toward the subject and reflected from the surface of the subject.

[0070] The optical system 407 is configured to have one or more lenses, and guides image light (incident light) from a subject to a photoelectric conversion device 408 , forming an image on the light receiving surface (sensor portion) of the photoelectric conversion device 408 .

[0071] As the photoelectric conversion device 408 , the photoelectric conversion device of each of the above-mentioned embodiments is applied, and a distance signal indicating a distance determined from a light reception signal output from the photoelectric conversion device 408 is supplied to the image processing circuit 404 .

[0072] The image processing circuit 404 performs image processing to construct a distance image based on the distance signal supplied from the photoelectric conversion device 408. The distance image (image data) obtained by this image processing is then supplied to a monitor 405 for display, or supplied to a memory 406 for storage (recording).

[0073] In the range image sensor 401 configured in this way, by applying the above-described photoelectric conversion device, it is possible to obtain, for example, a more accurate range image as the pixel characteristics improve.

[0074] (Eleventh embodiment) The photoelectric conversion system of this embodiment will be described with reference to Fig. 15. Fig. 15 is a diagram showing an example of a schematic configuration of an endoscopic surgery system which is the photoelectric conversion system of this embodiment.

[0075] 15 shows a state in which an operator (doctor) 1131 is performing surgery on a patient 1132 on a patient bed 1133 using an endoscopic surgery system 1150. As shown in the figure, the endoscopic surgery system 1150 is composed of an endoscope 1100, a surgical tool 1110, and a cart 1134 on which various devices for endoscopic surgery are mounted.

[0076] The endoscope 1100 is composed of a lens barrel 1101, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 1132, and a camera head 1102 connected to the base end of the lens barrel 1101. In the illustrated example, the endoscope 1100 is configured as a so-called rigid lens barrel having a rigid lens barrel 1101, but the endoscope 1100 may be configured as a so-called flexible lens barrel having a flexible lens barrel.

[0077] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 1101. A light source device 1203 is connected to the endoscope 1100, and light generated by the light source device 1203 is guided to the tip of the lens barrel 1101 by a light guide extending inside the lens barrel 1101, and is irradiated via the objective lens toward an observation target in a body cavity of a patient 1132. The endoscope 1100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0078] An optical system and a photoelectric conversion device are provided inside the camera head 1102, and reflected light (observation light) from an observation target is collected by the optical system onto the photoelectric conversion device. The observation light is photoelectrically converted by the photoelectric conversion device to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to an observation image. The photoelectric conversion device described in each of the above-mentioned embodiments can be used as the photoelectric conversion device. The image signal is transmitted to a camera control unit (CCU) 1135 as RAW data.

[0079] The CCU 1135 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and performs overall control of the operations of the endoscope 1100 and the display device 1136. Furthermore, the CCU 1135 receives an image signal from the camera head 1102, 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.

[0080] Under the control of the CCU 1135 , the display device 1136 displays an image based on an image signal that has been subjected to image processing by the CCU 1135 .

[0081] The light source device 1203 is composed of a light source such as an LED (Light Emitting Diode), and supplies the endoscope 1100 with irradiation light when photographing an operation site or the like.

[0082] The input device 1137 is an input interface for the endoscopic surgery system 1150. A user can input various information and instructions to the endoscopic surgery system 1150 via the input device 1137.

[0083] The treatment tool control device 1138 controls the driving of the energy treatment tool 1112 for cauterizing tissue, incising, sealing blood vessels, or the like.

[0084] The light source device 1203 that supplies irradiation light to the endoscope 1100 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 1203. 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 target 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 1102 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.

[0085] Furthermore, the light source device 1203 may be controlled to change the intensity of the light it outputs at predetermined time intervals. By controlling the driving of the image sensor of the camera head 1102 in synchronization with the timing of the change in the light intensity to acquire images in a time-division manner and synthesizing the images, it is possible to generate an image with a high dynamic range that is free of so-called blocked-up shadows and blown-out highlights.

[0086] The light source device 1203 may be configured to supply light in a predetermined wavelength band corresponding to the special light observation. In the special light observation, for example, the wavelength dependency of light absorption in body tissue is utilized. Specifically, a predetermined tissue such as blood vessels on the mucous membrane surface is photographed with high contrast by irradiating light in a narrower band than the irradiation light (i.e., white light) in normal observation. Alternatively, the special light observation may be a fluorescent observation in which an image is obtained by fluorescence generated by irradiating excitation light. In the fluorescent observation, it is possible to irradiate excitation light to the body tissue and observe the fluorescence from the body tissue, 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 1203 may be configured to supply narrow band light and / or excitation light corresponding to such special light observation.

[0087] (Twelfth embodiment) The photoelectric conversion system of this embodiment will be described with reference to Figs. 16(a) and (b). Fig. 16(a) describes glasses 1600 (smart glasses) which are the photoelectric conversion system of this embodiment. The glasses 1600 have a photoelectric conversion device 1602. The photoelectric conversion device 1602 is the photoelectric conversion device described in each of the above embodiments. A display device including a light-emitting device such as an OLED or LED may be provided on the rear side of the lens 1601. The photoelectric conversion device 1602 may be one or more. A combination of multiple types of photoelectric conversion devices may also be used. The arrangement position of the photoelectric conversion device 1602 is not limited to that shown in Fig. 16(a).

[0088] The glasses 1600 further include a control device 1603. The control device 1603 functions as a power source that supplies power to the photoelectric conversion device 1602 and the display device. The control device 1603 also controls the operations of the photoelectric conversion device 1602 and the display device. The lens 1601 is formed with an optical system for focusing light on the photoelectric conversion device 1602.

[0089] FIG. 16(b) illustrates glasses 1610 (smart glasses) according to one application example. The glasses 1610 have a control device 1612, and the control device 1612 is equipped with a photoelectric conversion device corresponding to the photoelectric conversion device 1602 and a display device. The lens 1611 is formed with an optical system for projecting light emitted from the photoelectric conversion device in the control device 1612 and the display device, and an image is projected onto the lens 1611. The control device 1612 functions as a power source for supplying power to the photoelectric conversion device and the display device, and controls the operation of the photoelectric conversion device and the display device. The control device may have a line of sight detection unit that detects the line of sight of the wearer. Infrared light may be used for detecting the line of sight. The infrared light emission unit emits infrared light to the eyeball of a user gazing at a display image. An imaging unit having a light receiving element detects the reflected light of the emitted infrared light from the eyeball, thereby obtaining an image of the eyeball. By having a reduction means for reducing light from the infrared light emission unit to the display unit in a planar view, deterioration of image quality is reduced.

[0090] The gaze of the user with respect to the displayed image is detected from an image of the eyeball obtained by capturing infrared light. Any known method can be applied to gaze detection using the image of the eyeball. As an example, a gaze detection method based on a Purkinje image formed by reflection of irradiated light on the cornea can be used.

[0091] More specifically, the gaze detection process is performed based on the pupil-corneal reflex method. Using the pupil-corneal reflex method, a gaze vector that indicates the direction (rotation angle) of the eyeball is calculated based on the pupil image and the Purkinje image included in the captured image of the eyeball, thereby detecting the user's gaze.

[0092] The display device of this embodiment may have a photoelectric conversion device having a light receiving element, and may control the display image of the display device based on information about the user's line of sight from the photoelectric conversion device.

[0093] Specifically, the display device determines a first field of view area to which the user gazes and a second field of view area other than the first field of view area based on the line-of-sight information. The first field of view area and the second field of view area may be determined by a control device of the display device, or may be received from an external control device. In the display area of ​​the display device, the display resolution of the first field of view area may be controlled to be higher than the display resolution of the second field of view area. In other words, the resolution of the second field of view area may be lower than that of the first field of view area.

[0094] The display area may have a first display area and a second display area different from the first display area, and a high priority area may be determined from the first display area and the second display area based on line-of-sight information. The first field of view area and the second field of view area may be determined by a control device of the display device, or may be determined by an external control device and received. The resolution of the high priority area may be controlled to be higher than the resolution of areas other than the high priority area. In other words, the resolution of an area with a relatively low priority may be lowered.

[0095] AI may be used to determine the first field of view area and areas with high priority. The AI ​​may be a model configured to estimate the angle of the line of sight and the distance to an object at the end of the line of sight from the image of the eyeball, using as teacher data an image of the eyeball and the direction in which the eyeball in the image was actually looking. The AI ​​program may be included in the display device, the photoelectric conversion device, or an external device. If included in the external device, it is transmitted to the display device via communication.

[0096] When display control is performed based on visual recognition detection, the present invention is preferably applicable to smart glasses further including a photoelectric conversion device for capturing an image of the outside world. The smart glasses can display captured outside information in real time.

[0097] [Modified embodiment] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, an example in which a part of the configuration of any of the embodiments is added to another embodiment, or an example in which a part of the configuration of another embodiment is replaced with another embodiment is also included in the embodiments of the present invention.

[0098] Further, the photoelectric conversion systems shown in the eighth and ninth embodiments are examples of photoelectric conversion systems to which a photoelectric conversion device can be applied, and photoelectric conversion systems to which the photoelectric conversion device of the present invention can be applied are not limited to the configurations shown in Fig. 12 to Fig. 16. The same applies to the ToF system shown in the tenth embodiment, the endoscope shown in the eleventh embodiment, and the smart glasses shown in the twelfth embodiment.

[0099] It should be noted that the above-mentioned embodiments are merely examples of the implementation of the present invention, and the technical scope of the present invention should not be interpreted as being limited by these embodiments. In other words, the present invention can be implemented in various forms without departing from its technical concept or main features.

[0100] The present disclosure has the following configuration.

[0101] (Configuration 1) The photoelectric conversion device includes a first component having a first semiconductor substrate having a first surface and a second surface facing the first surface, a photoelectric conversion unit provided on the first semiconductor substrate, a floating diffusion unit, and a transfer gate provided on the first surface side of the first semiconductor substrate and transferring a signal charge generated in the photoelectric conversion unit to the floating diffusion unit. The first component includes a first embedded electrode connected to the photoelectric conversion unit and a second embedded electrode connected to the floating diffusion unit. The photoelectric conversion device is characterized in that a depth from the first surface to an end of the first embedded electrode on the second surface side is different from a depth from the first surface to an end of the second embedded electrode on the second surface side.

[0102] (Configuration 2) The photoelectric conversion device according to configuration 1, further comprising a second component having a second semiconductor substrate and stacked on the first component.

[0103] (Configuration 3) The photoelectric conversion device according to configuration 2, wherein the second semiconductor substrate has a third surface and a fourth surface facing the third surface, the first component and the second component are stacked such that the second surface and the third surface face each other, and a through electrode penetrating from the third surface to the fourth surface, and a gate of an amplifying transistor is formed on the fourth surface.

[0104] (Configuration 4) The photoelectric conversion device described in any one of configurations 1 to 3, characterized in that the first embedded electrode connects the floating diffusion portion and the gate of the amplifying transistor and is an electrode that transfers a signal based on charges generated in the photoelectric conversion portion.

[0105] (Configuration 5) 5. The photoelectric conversion device according to any one of configurations 1 to 4, wherein the second embedded electrode is an electrode that applies a voltage to the photoelectric conversion portion.

[0106] (Configuration 6) A photoelectric conversion device described in any one of configurations 1 to 5, characterized in that a depth from the first surface to an end of the first embedded electrode on the second surface side is deeper than a depth from the first surface to an end of the second embedded electrode on the second surface side.

[0107] (Configuration 7) A first semiconductor region of a first conductivity type is formed around the first buried electrode, and a second semiconductor region of a second conductivity type is formed around the second buried electrode. In comparison with the first surface, an end of the first semiconductor region on the second surface side is closer to the second surface than an end of the second semiconductor region on the second surface side.

[0108] (Configuration 8) A photoelectric conversion device described in any one of configurations 1 to 5, characterized in that a depth from the first surface to an end of the second embedded electrode on the second surface side is deeper than a depth from the first surface to an end of the first embedded electrode on the second surface side.

[0109] (Configuration 9) A first semiconductor region of a first conductivity type is formed around the first buried electrode, and a second semiconductor region of a second conductivity type is formed around the second buried electrode. In comparison with the first surface, an end of the second semiconductor region on the second surface side is closer to the second surface than an end of the first semiconductor region on the second surface side.

[0110] (Configuration 10) The photoelectric conversion device according to any one of configurations 1 to 9, wherein the transfer gate is a vertical transfer gate.

[0111] (Configuration 11) 4. The photoelectric conversion device according to claim 3, wherein the through electrode is connected to a plurality of first buried electrodes.

[0112] (Configuration 12) The photoelectric conversion device according to any one of configurations 1 to 11, further comprising: a photoelectric conversion unit having a depth from the first surface to an end of the first embedded electrode on the second surface side different from a depth from the first surface to an end of the second embedded electrode on the second surface side, and a photoelectric conversion unit having a depth from the first surface to an end of the first embedded electrode on the second surface side equal to a depth from the first surface to an end of the second embedded electrode on the second surface side.

[0113] (Configuration 13) 13. A photoelectric conversion system comprising: a photoelectric conversion device according to any one of configurations 1 to 12; and a signal processing unit that generates an image using a signal output from the photoelectric conversion device.

[0114] (Configuration 14) 13. A moving body including a photoelectric conversion device according to any one of claims 1 to 12, further comprising a control unit that controls the movement of the moving body using a signal output by the photoelectric conversion device. [Explanation of symbols]

[0115] 101 Photodiode (PD) 111 Transfer transistor 121 Floating Diffusion (FD) 221 First embedded electrode 241 Second embedded electrode

Claims

1. A first semiconductor substrate having a first surface and a second surface facing the first surface, The photoelectric conversion unit provided on the first semiconductor substrate, Floating diffusion section, The first component includes a transfer gate provided on the first surface side of the first semiconductor substrate, which transfers the signal charge generated in the photoelectric conversion unit to the floating diffusion unit, The first component comprises a first embedded electrode connected to the photoelectric conversion unit and a second embedded electrode connected to the floating diffusion unit. A photoelectric conversion device characterized in that the depth from the first surface to the end of the first embedded electrode on the second surface side is different from the depth from the first surface to the end of the second embedded electrode on the second surface side.

2. The photoelectric conversion device according to claim 1, characterized in that it comprises a second semiconductor substrate and a second component that is stacked on the first component.

3. The second semiconductor substrate comprises a third surface and a fourth surface facing the third surface. The first part and the second part are stacked such that their first and third surfaces face each other. It has a through electrode that penetrates from the third surface to the fourth surface, The photoelectric conversion device according to claim 2, characterized in that the gate of an amplifying transistor is formed on the fourth surface.

4. The photoelectric conversion apparatus according to claim 3, characterized in that the second embedded electrode connects the floating diffusion unit and the gate of the amplification transistor and is an electrode that transfers a signal based on the charge generated in the photoelectric conversion unit.

5. The photoelectric conversion device according to claim 1, characterized in that the first embedded electrode is an electrode that applies a voltage to the photoelectric conversion unit.

6. The photoelectric conversion apparatus according to claim 1, characterized in that the depth from the first surface to the end of the first embedded electrode on the second surface side is greater than the depth from the first surface to the end of the second embedded electrode on the second surface side.

7. A first semiconductor region of a first conductivity type is formed around the first embedded electrode. A second semiconductor region of a second conductivity type is formed around the second embedded electrode. The photoelectric conversion device according to claim 6, characterized in that, in comparison from the first surface, the end of the first semiconductor region on the second surface side is closer to the second surface than the end of the second semiconductor region on the second surface side.

8. The photoelectric conversion apparatus according to claim 1, characterized in that the depth from the first surface to the end of the second embedded electrode on the second surface side is greater than the depth from the first surface to the end of the first embedded electrode on the second surface side.

9. A first semiconductor region of a first conductivity type is formed around the first embedded electrode. A second semiconductor region of a second conductivity type is formed around the second embedded electrode. The photoelectric conversion device according to claim 8, characterized in that, in comparison from the first surface, the end of the second semiconductor region on the second surface side is closer to the second surface than the end of the first semiconductor region on the second surface side.

10. The photoelectric conversion device according to claim 1, characterized in that the transfer gate is a vertical transfer gate.

11. The photoelectric conversion device according to claim 3, characterized in that the through electrode is connected to a plurality of first embedded electrodes.

12. It has multiple photoelectric conversion units, A photoelectric conversion unit in which the depth from the first surface to the end of the first embedded electrode on the second surface side and the depth from the first surface to the end of the second embedded electrode on the second surface side are different, The photoelectric conversion apparatus according to claim 1, characterized in that it includes a photoelectric conversion unit in which the depth from the first surface to the end of the first embedded electrode on the second surface side is equal to the depth from the first surface to the end of the second embedded electrode on the second surface side.

13. A photoelectric conversion device according to any one of claims 1 to 12, A photoelectric conversion system characterized by having a signal processing unit that generates an image using the signal output by the aforementioned photoelectric conversion device.

14. A mobile body comprising a photoelectric converter according to any one of claims 1 to 12, A mobile body characterized by having a control unit that controls the movement of the mobile body using a signal output by the photoelectric converter.

Images