Image pickup element and electronic apparatus

Abstract

An image pickup element according to an embodiment of the present disclosure includes: a semiconductor substrate having a photoelectric conversion portion for each pixel; one or more pixel transistors disposed on one surface of the semiconductor substrate; and a first element isolation portion and a second element isolation portion embedded in the one surface of the semiconductor substrate, defining an active region of the one or more pixel transistors, and having different depths. In the one or more pixel transistors, a portion of a gate electrode is buried at different depths in at least one of the first element isolation portion and the second element isolation portion.

Description

Technical Field

[0001] The present invention relates to an imaging element and electronic equipment. Background Art

[0002] For example, Patent Document 1 discloses a solid-state imaging element that is intended to improve area efficiency in the following manner: semiconductor regions having impurity concentrations different from each other are formed along the depth direction of an isolation portion in a side of an isolation portion with STI and an isolation portion with DTI that define an active area of ​​a pixel transistor. Citation list Patent Literature

[0003] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-13817 Summary of the invention

[0004] Incidentally, improvement in the image quality of image pickup elements is desired.

[0005] It is desirable to provide an image pickup element and electronic equipment capable of improving image quality.

[0006] The imaging element of an embodiment of the present disclosure includes: a semiconductor substrate containing a photoelectric conversion unit for each pixel; one or more pixel transistors arranged in one surface of the semiconductor substrate; and a first element isolation unit and a second element isolation unit of different depths from each other, which are buried in the one surface of the semiconductor substrate and define the active area of ​​the one or more pixel transistors, wherein a portion of the gate electrode of the one or more pixel transistors is buried at different depths in at least one of the first element isolation unit and the second element isolation unit.

[0007] An electronic device according to an embodiment of the present disclosure includes the imaging element according to an embodiment of the present disclosure.

[0008] In the imaging element and the electronic device of the embodiments of the present disclosure, a portion of the gate electrode of the one or more pixel transistors is buried at different depths in at least one of the first element isolation portion and the second element isolation portion which are provided at the semiconductor substrate and define the active region of the one or more pixel transistors. Thus, the shape of the channel region formed under the gate electrode is controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] [ Figure 1 ] Figure 1 is a schematic cross-sectional view showing the configuration of a main part of an image pickup element according to a first embodiment of the present invention. [ Figure 2 ] Figure 2 yes Figure 1 Schematic plan view of the imaging element shown. [ Figure 3 ] Figure 3 It shows that including Figure 1 A block diagram of the overall structure of an imaging device including an imaging element shown. [ Figure 4 ] Figure 4 yes Figure 3 The equivalent circuit diagram of each unit pixel of the imaging device shown. [ Figure 5A ] Figure 5A Yes Description Figure 1 Schematic cross-sectional views showing an example of a manufacturing process of an imaging element shown. [ Figure 5B ] Figure 5B It shows Figure 5A Schematic cross-sectional view of the subsequent process steps. [ Figure 5C ] Figure 5C It shows Figure 5B Schematic cross-sectional view of the subsequent process steps. [ Figure 5D ] Figure 5D It shows Figure 5C Schematic cross-sectional view of the subsequent process steps. [ Figure 6 ] Figure 6 : is a schematic cross-sectional view showing the configuration of a main part of an image pickup element according to Modification 1 of the present invention. [ Figure 7 ] Figure 7 : is a schematic cross-sectional view showing the configuration of a main part of an image pickup element according to Modification 2 of the present invention. [ Figure 8 ] Figure 8 yes Figure 7 Schematic plan view of the imaging element shown. [ Fig. 9 ] Fig. 9 yes Figure 8 A schematic cross-sectional view of the FD conversion gain switching transistor is shown. [ Fig.10 ] Fig.10 It shows Figure 7 Graph showing the potential under the gate electrode of the imaging element. [ Fig.11 ] Fig.11 is a schematic cross-sectional view showing a configuration example of a main part of an image pickup element according to a second embodiment of the present invention. [ Fig.12 ] Fig.12 yes Fig.11 Schematic plan view of the imaging element shown. [ Fig.13 ] Fig.13 : is a schematic cross-sectional view showing the configuration of a main part of an image pickup element according to Modification 3 of the present invention. [ Fig.14 ] Fig.14 : is a schematic cross-sectional view showing the configuration of a main part of an image pickup element according to Modification 4 of the present invention. [ Fig.16 ] Fig.16 It shows Fig.14 Graph showing the potential under the gate electrode of the imaging element. [ Fig.15 ] Fig.15 yes Fig.14 Schematic plan view of the imaging element shown. [ Fig.17 ] Fig.17 It shows the use of Figure 3 A block diagram showing an example of the configuration of electronic equipment of an imaging device shown. [ Fig.18A ] Fig.18A It shows the use of Figure 3 FIG. 1 is a schematic diagram of an example of the overall configuration of a light detection system of an image pickup device shown in FIG. [ Fig.18B ] Fig.18B It shows Fig.18A A diagram showing an example of a circuit configuration of a light detection system. [ Fig.19 ] Fig.19 is a diagram showing an example of a schematic configuration of an endoscopic surgery system. [ Fig. 20 ] Fig. 20 is a block diagram showing an example of a functional configuration of a camera head and a camera control unit (CCU). [ Fig.21 ] Fig.21 is a block diagram showing an example of a schematic configuration of a vehicle control system. [ Fig. 22 ] Fig. 22 It is a diagram for assisting in explaining an example of the installation positions of the vehicle exterior information detection unit and the imaging unit. DETAILED DESCRIPTION

[0010] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following description is a specific example of the present invention, and the present invention is not limited to the following aspects. In addition, the layout, size, size ratio, etc. of each component shown in each figure are not limited to these. It should be noted that the description order is as follows. 1. First Implementation Method (Example of an imaging device in which a portion of the gate electrode is buried in STI) 2. Modification 1 (Example of an imaging element in which a portion of the gate electrode is buried in both the STI and FTI so that the portion on the STI side is buried deeper) 3. Modification 2 (Example of providing a high-concentration impurity diffusion layer on the side of FTI) 4. Second Implementation Plan (Example of an imaging element in which a portion of the gate electrode is embedded in the FTI) 5. Modification 3 (Example of an imaging element in which a portion of the gate electrode is buried in both the STI and the FTI so that the portion on the FTI side is buried deeper) 6. Modification 4 (Example of providing a high-concentration impurity diffusion layer under STI) 7. Application examples 8. Practical application examples

[0011] <1. First Implementation Plan> Figure 1 The cross-sectional configuration of the main part of the image pickup element (image pickup element 1 ) according to the first embodiment of the present invention is schematically shown. Figure 2 Schematically shows Figure 1 The planar structure of the imaging element 1 shown in FIG. Figure 1 Shown along Figure 2 For example, the imaging element 1 constitutes an imaging device such as a complementary metal oxide semiconductor (CMOS) image sensor used in an electronic device such as a digital camera or a video camera (the imaging device 100, see Figure 3 ) in a pixel (unit pixel P).

[0012] [Overall structure of the camera device] Figure 3 The overall configuration of an image pickup apparatus (image pickup apparatus 100 ) according to an embodiment of the present invention is shown.

[0013] For example, the image pickup device 100 receives incident light (image light) from a subject through an optical lens system (not shown), and converts the amount of incident light formed as an image on an image pickup surface into an electric signal pixel by pixel, and outputs the electric signal as a pixel signal. The image pickup device 100 includes a pixel portion 100A as an image pickup area on a semiconductor substrate 11, and includes, for example, a vertical drive circuit 111, a column signal processing circuit 112, a horizontal drive circuit 113, an output circuit 114, a control circuit 115, and an input / output terminal 116 in an area around the pixel portion 100A.

[0014] The pixel section 100A includes, for example, a plurality of unit pixels P arranged two-dimensionally in a matrix. These unit pixels P are provided with, for example, a pixel drive line Lread (specifically, a row selection line and a reset control line) for each pixel row and a vertical signal line Lsig for each pixel column. The pixel drive line Lread is used to transmit a drive signal for reading a signal from the unit pixel P. One end of the pixel drive line Lread is connected to an output end of the vertical drive circuit 111 corresponding to each row.

[0015] The vertical drive circuit 111 is a pixel driving unit including a shift register, an address decoder, and the like, and drives each unit pixel P in the pixel section 100A row by row, for example. Signals output from each unit pixel P of a pixel row selected and scanned by the vertical drive circuit 111 are supplied to the column signal processing circuit 112 through the vertical signal line Lsig. The column signal processing circuit 112 includes an amplifier and a horizontal selection switch, and the like, provided for each vertical signal line Lsig.

[0016] The horizontal driving circuit 113 includes a shift register, an address decoder, etc., and sequentially drives each horizontal selection switch of the column signal processing circuit 112 while scanning. Through such selective scanning by the horizontal driving circuit 113, the signal of each pixel transmitted through the corresponding vertical signal line Lsig is sequentially output to the horizontal signal line 117, and is transmitted to the outside of the semiconductor substrate 11 through the horizontal signal line 117.

[0017] The output circuit 114 performs signal processing on the signals sequentially supplied from the respective column signal processing circuits 112 through the horizontal signal line 117, and outputs the processed signals. For example, the output circuit 114 performs only buffering in some cases, and performs black level adjustment, column difference correction, various digital signal processing, etc. in other cases.

[0018] The circuit portion including the vertical drive circuit 111, the column signal processing circuit 112, the horizontal drive circuit 113, the horizontal signal line 117, and the output circuit 114 may be directly formed on the semiconductor substrate 11, or may be provided in an external control IC. In addition, the circuit portion may be formed on other substrates connected by cables or other means.

[0019] The control circuit 115 receives a clock supplied from the outside of the semiconductor substrate 11, data commanding an operation mode, and the like, and outputs data such as internal information of the image pickup device 100. In addition, the control circuit 115 includes a timing generator that generates various timing signals, and performs control of driving peripheral circuits such as the vertical drive circuit 111, the column signal processing circuit 112, and the horizontal drive circuit 113 based on the various timing signals generated by the timing generator.

[0020] The input / output terminal 116 exchanges signals with the outside.

[0021] [Circuit structure of imaging element (unit pixel)] Figure 4 An example of an equivalent circuit (pixel circuit) of a unit pixel P is shown. The unit pixel P is provided with a plurality of transistors. In order to drive these plurality of transistors, a plurality of pixel driving lines Lread are connected to one unit pixel P. The unit pixel P is connected to a vertical signal line Lsig.

[0022] The unit pixel P includes, for example, a photoelectric conversion portion 12 including a photodiode (PD), a transfer transistor (TRG) 21, and a floating diffusion region (FD) 22 electrically connected to the TRG 21. In the photoelectric conversion portion 12, a cathode is electrically connected to a source of the TRG 21, and an anode is electrically connected to a reference potential line (for example, ground).

[0023] The photoelectric conversion unit 12 performs photoelectric conversion on the incident light, and generates charges according to the amount of light received. TRG 21 is, for example, an n-type complementary metal oxide semiconductor (CMOS) transistor. In TRG 21, the drain is electrically connected to FD 22, and the gate is connected to a pixel drive line Lread. The pixel drive line Lread is a part of a plurality of pixel drive lines Lread connected to one unit pixel P. TRG 21 transfers the charges generated by the photoelectric conversion unit 12 to FD 22. FD 22 is, for example, an n-type diffusion layer formed in a p-well of the semiconductor substrate 11. FD 22 is a charge holding device that temporarily holds the charges transferred from the photoelectric conversion unit 12, and is a charge-voltage conversion device that generates a voltage according to the amount of charge.

[0024] The pixel circuit includes, for example, four types of transistors, specifically, a reset transistor (RST) 23 , an amplifier transistor (AMP) 24 , a selection transistor (SEL) 25 , and an FD conversion gain switching transistor (FDG) 26 .

[0025] FD 22 is electrically connected to the gate of AMP 24 and the source of FDG 26. The drain of FDG 26 is connected to the source of RST 23, and the gate of FDG 26 is connected to the pixel drive line Lread. The pixel drive line Lread is a part of a plurality of pixel drive lines Lread connected to one unit pixel P. The drain of RST 23 is connected to the power supply line VDD, and the gate of RST is connected to the pixel drive line Lread. The pixel drive line Lread is a part of a plurality of pixel drive lines Lread connected to one unit pixel P. The gate of AMP 24 is connected to FD 22, the source of AMP 24 is connected to the drain of SEL 25, and the drain of AMP 24 is connected to the power supply line VDD. The source of SEL 25 is connected to the vertical signal line Lsig, and the gate of SEL 25 is connected to the pixel drive line Lread. The pixel drive line Lread is a part of a plurality of pixel drive lines Lread connected to one unit pixel P.

[0026] If TRG 21 enters the on state, TRG 21 transfers the charge in the photoelectric conversion unit 12 to FD 22. The gate (transfer gate) of TRG 21 includes, for example, a so-called vertical electrode, and extends, for example, from the front side (surface 11S1) of the semiconductor substrate 11 to a depth reaching the photoelectric conversion unit 12. RST 23 resets the potential of FD 22 to a predetermined potential. If RST 23 enters the on state, RST 23 resets the potential of FD 22 to the potential of the power supply line VDD. SEL 25 controls the timing of outputting a pixel signal from the pixel circuit. AMP 24 generates a voltage signal as a pixel signal according to the level of the charge held in FD 22. AMP 24 is connected to the vertical signal line Lsig through SEL 25. AMP 24 constitutes a source follower in the column signal processing circuit 112. If SEL 25 enters the on state, AMP 24 outputs the voltage of FD 22 to the column signal processing circuit 112 through the vertical signal line Lsig. RST 23 , AMP 24 , and SEL 25 are, for example, n-type CMOS transistors.

[0027] FDG 26 is used to change the gain of the charge-voltage conversion of FD 22. Generally, when an image is taken in a dark place, the pixel signal is small. Based on Q = CV, when the charge-voltage conversion is performed, if the capacitance (FD capacitance C) of FD 22 is high, the voltage V converted in AMP 24 becomes low. On the other hand, the pixel signal becomes large in a bright place, so if the FD capacitance C is not high, FD 22 cannot accept the charge of the photoelectric conversion unit 12. In addition, the FD capacitance C must be high so that the converted voltage V in AMP 24 is not too high (that is, it becomes low). In view of these, when FDG 26 is already turned on, the gate capacitance of FDG 26 is increased, so the entire FD capacitance C becomes high. At the same time, when FDG 26 is already turned off, the entire FD capacitance C becomes low. In this way, by switching the on and off of FDG 26, the FD capacitance C becomes variable, and the conversion efficiency can be switched. FDG 26 is, for example, an n-type CMOS transistor.

[0028] Note that a configuration without FDG 26 is also possible. In this case, for example, the pixel circuit includes three transistors: RST 23, AMP 24, and SEL 25. The pixel circuit includes at least one transistor among RST 23, AMP 24, SEL 25, and FDG 26, for example.

[0029] In addition, the SEL 25 may be provided between the power supply line VDD and the AMP 24. In this case, the drain of the RST 23 is electrically connected to the power supply line VDD and the drain of the SEL 25. The source of the SEL 25 is electrically connected to the drain of the AMP 24, and the gate of the SEL 25 is electrically connected to the pixel drive line Lread. The source of the AMP 24 (the output terminal of the pixel circuit) is electrically connected to the vertical signal line Lsig, and the gate of the AMP 24 is electrically connected to the source of the RST 23.

[0030] Hereinafter, the RST 23, the AMP 24, the SEL 25, and the FDG 26 are referred to as pixel transistors.

[0031] [Structure of the imaging element] As described above, the image pickup element 1 constituting the unit pixel P includes the photoelectric conversion section 12, the TRG 21, and the FD 22, and further includes the RST 23, the AMP 24, the SEL 25, and the FDG 26 as pixel transistors. Figure 1As shown, the photoelectric conversion unit 12 is formed to be buried in the semiconductor substrate 11, and the FD 22, RST 23, AMP 24, SEL 25, and FDG 26 are provided on the front side (surface 11S1) of the semiconductor substrate 11. It is to be noted that, although not shown, a color filter and an on-chip lens are provided on the surface (back side) on the side opposite to the front side (surface 11S1) of the semiconductor substrate 11. The imaging element 1 is a so-called back-illuminated imaging element, which uses the above-mentioned back side of the semiconductor substrate 11 as a light receiving surface, and a wiring layer for driving, for example, a pixel transistor provided for each unit pixel P is provided on the front side (surface 11S1).

[0032] It should be noted that the symbols "p" and "n" in the drawings represent p-type semiconductor regions and n-type semiconductor regions, respectively. In addition, the "+ (plus sign)" after "p" and "n" indicates that the p-type or n-type impurity concentration is higher than the impurity concentration of the surrounding p-type or n-type semiconductor regions. The same is true for subsequent drawings.

[0033] The semiconductor substrate 11 includes, for example, a silicon (Si) substrate and has a p-type semiconductor region (p) (p-well) adjacent to the front surface (surface 11S1 ), and an n-type semiconductor region (n) constituting a photodiode is provided in a predetermined region.

[0034] The photoelectric conversion section 12 includes, for example, a PIN (Positive-Intrinsic-Negative) type photodiode, and as described above, has, for example, a pn junction for each unit pixel p.

[0035] The semiconductor substrate 11 is provided with element isolation parts 13 and 14. The element isolation part 13 corresponds to a specific example of the "first element isolation part" of the present invention, and, for example, electrically isolates each pixel transistor provided in the unit pixel P. The element isolation part 13 has, for example, an STI (shallow trench isolation) structure. The element isolation part 14 corresponds to a specific example of the "second element isolation part" of the present invention, and electrically isolates adjacent unit pixels P. In the thickness direction (Z-axis direction) of the semiconductor substrate 11, the element isolation part 14 is formed to be deeper than the element isolation part 13, and has, for example, an FTI (full trench isolation) structure in which a groove penetrates the semiconductor substrate 11 between the front side (surface 11S1) and the back side of the semiconductor substrate 11.

[0036] The element isolation parts 13 and 14 define the active region 11A of the plurality of pixel transistors (RST 23, AMP 24, SEL 25, and FDG 26) provided in the unit pixel P. The active region 11A of the pixel transistors is, for example, Figure 2The region forming the gate electrode and source / drain of the pixel transistor is shown. Specifically, it has the following structure: wherein a channel region (for example, as shown in FIG. 1 ) is formed between the source and the drain below the gate electrode of the pixel transistor. Figure 1 As shown, the length (channel length (W)) of the channel region 11X formed below the gate electrode 24G of the AMP 24 is defined by the element isolation portion 13 and the element isolation portion 14 .

[0037] In the pixel section 100A, the element isolation section 14 is provided in a grid pattern, for example, to separate the unit pixels P adjacent in the row direction and the column direction. In the unit pixel P, the element isolation section 13 is provided between the RST 23, the AMP 24, and the SEL 25 (for example, arranged side by side in the Y-axis direction) and the TRG 21 and the FDG 26 (for example, arranged side by side in the Y-axis direction). The element isolation sections 13 and 14 are formed using, for example, silicon oxide (SiO x ) and other materials to form.

[0038] Below the element isolation portion 13, a p-type diffusion layer (p+) 15 is provided. The p-type diffusion layer (p+) 15 corresponds to a specific example of the "first impurity diffusion layer" of the present invention. The p-type diffusion layer (p+) 15 is used to suppress the formation of a groove (for example, the opening 11H, see FIG. 11 ) included in the element isolation portion 13. Figure 5B ) caused by defects.

[0039] In the present embodiment, a portion of the gate electrodes of all or some of the plurality of pixel transistors (RST 23, AMP 24, SEL 25, and FDG 26) included in the pixel circuit is buried in the element isolation portion 13. Therefore, when each pixel transistor enters the on state, the depth of the channel region 11X formed in the active region 11A under the gate electrode can be suppressed. Specifically, as Figure 1 As shown, by burying a part (buried portion 24X) of, for example, the gate electrode 24G of the AMP 24, the channel region 11X which is usually formed deep on the element isolation portion 14 side due to the depth difference and impurity concentration deviation between the element isolation portions 13 and 14 can also be formed deep on the element isolation portion 13 side. That is, the channel region 11X formed in the active region 11A below the gate electrode 24G is formed between the element isolation portion 13 and the element isolation portion 14 at a substantially uniform depth.

[0040] [Method for manufacturing imaging element] The gate electrode (for example, the gate electrode 24G) of the image sensor 1 according to the present embodiment can be formed, for example, as follows.

[0041] First, if Figure 5AAs shown, the element isolation parts 13 and 14 are formed and the n-type semiconductor region (n) serving as the photoelectric conversion part 12 and the p-type diffusion layer (p+) 15 are formed in the semiconductor substrate 11 by ion implantation. Then, as shown in FIG. Figure 5B As shown, the resist 31 is patterned on the front surface (surface 11S1 ) of the semiconductor substrate 11 by photolithography and etching, and the opening 11H is formed in the element isolation portion 13 .

[0042] Next, if Figure 5C As shown, after removing the resist 31, although not shown, an insulating film is formed on the front surface (surface 11S1) of the semiconductor substrate 11 and the side and bottom surfaces of the opening 11H, and a gate insulating film of each pixel transistor is formed. Then, after forming a conductive film using a sputtering technique, the conductive film is processed by photolithography and etching. Figure 5D As shown, a gate electrode partially buried in the element isolation portion 13 (for example, a gate electrode 24G having a buried portion 24X) is formed. [Image sensor operation]

[0043] In the image pickup element 1, for example, as a unit pixel P of the image pickup device 100, signal charge (for example, electrons) is acquired as follows. If light enters the image pickup element 1 through the on-chip lens, the light passes through a color filter or the like, and is detected (absorbed) by the photoelectric conversion section 12 provided for each unit pixel P, and light of a predetermined wavelength is photoelectrically converted. Among the electron-hole pairs generated in the photoelectric conversion section 12, for example, electrons move and accumulate in the n-type semiconductor region (+), and holes are discharged from the power supply line VDD. [Function and Effect]

[0044] In the image pickup element 1 of the present embodiment, among the element isolation parts 13 and 14 provided in the semiconductor substrate 11 and having different depths from each other, which define the active regions 11A of the plurality of pixel transistors constituting the pixel circuit, a portion of the gate electrode of the pixel transistor (for example, the gate electrode 24G of the AMP 24) is buried in the element isolation part 13 having the STI structure. Therefore, the shape of the channel region 11X formed under the gate electrode is controlled. This is described in detail below.

[0045] As described above, in the case where the isolation portion defining the active area of ​​a plurality of pixel transistors constituting the pixel circuit is set to have different depths such as an STI structure and an FTI structure, the channel is formed deep on the FTI side due to their depth difference and the impurity concentration deviation caused by the p-type diffusion region formed directly below the STI for preventing dark current. This deviation in channel depth increases the characteristic difference of the pixel transistor. In particular, in image sensors, the characteristic difference of the amplifying transistor leads to degradation of image quality. In addition, the current is likely to flow to the sidewall interface of the FTI, thereby increasing the charge captured in the FTI interface having more defects than the interface with the gate oxide film, which leads to the deterioration of random telegraph signal (RTS) noise.

[0046] Meanwhile, in the present embodiment, a portion (buried portion 24X) of the gate electrodes of a plurality of pixel transistors constituting the pixel circuit (for example, the gate electrode 24G of the AMP 24) is buried in the element isolation portion 13 having the STI structure. Therefore, the channel region 11X formed under the gate electrode can also be formed deep on the element isolation portion 13 side, and a channel region 11X having a substantially uniform depth is formed between the element isolation portion 13 and the element isolation portion 14.

[0047] As above, in the image pickup element 1 and the image pickup device 100 of the present embodiment, the characteristic variation of the pixel transistors is improved, and the RTS noise is reduced, and thus the image quality can be improved.

[0048] A second embodiment of the present disclosure and Modifications 1 to 4 will be described below. Note that the same components as those of the above-described first embodiment are given the same reference numerals, and description thereof will be omitted accordingly.

[0049] <2. Modification 1> Figure 6 The cross-sectional structure of the main part of the image pickup element (image pickup element 1A) according to the modification 1 of the present invention is schematically shown. For example, the image pickup element 1A constitutes one pixel (unit pixel P) in the image pickup device 100 such as a CMOS image sensor used in electronic equipment such as a digital camera or a video camera, as in the above-mentioned first embodiment.

[0050] In the first embodiment described above, a portion (buried portion 24X) of the gate electrodes of a plurality of pixel transistors (e.g., the gate electrode 24G of the AMP 24) is buried in the element isolation portion 13 having the STI structure. In contrast, in the image pickup element 1A of the present modification, both the element isolation portion 13 having the STI structure and the element isolation portion 14 having the FTI structure are buried with a portion of the gate electrode (e.g., buried portion 24X or 24Y), and the buried portion 24X buried in the element isolation portion 13 is buried deeper than the buried portion 24Y buried in the element isolation portion 14. Except for this point, the image pickup element 1A has a configuration substantially similar to that of the image pickup element 1 according to the first embodiment described above.

[0051] In this way, in the imaging element 1A of the present variation, a portion of the gate electrodes of the plurality of pixel transistors is buried in each of the element isolation portion 13 having the STI structure and the element isolation portion 14 having the FTI structure, and is buried deeper in the pixel element isolation portion 13 than in the pixel element isolation portion 14. Therefore, even in the case where a portion of the gate electrode is buried in both the element isolation portion 13 and the element isolation portion 14, as in the above-mentioned first embodiment, a channel region 11X can be formed with a substantially uniform depth between the element isolation portion 13 and the element isolation portion 14. Therefore, the characteristic variation of the pixel transistors is improved, and the RTS noise is reduced, and thus the image quality can be improved.

[0052] <3. Modification 2> Figure 7 The cross-sectional structure of the main part of the image pickup element (image pickup element 1B) according to Modification 1 of the present invention is schematically shown. Figure 8 Schematically shows Figure 7 The planar structure of the imaging element 1B shown in FIG. Figure 7 Shown along Figure 8 For example, similarly to the first embodiment, the image pickup element 1B constitutes one pixel (unit pixel P) in an image pickup device 100 such as a CMOS image sensor used in electronic equipment such as a digital camera or a video camera.

[0053] In the first embodiment described above, a portion (buried portion 24X) of the gate electrodes of the plurality of pixel transistors (e.g., the gate electrode 24G of the AMP 24) is buried in the element isolation portion 13 having the STI structure. Meanwhile, in the image pickup element 1B of the present modification, in the vicinity of the element isolation portion 14 having the FTI structure, below the gate electrode of the pixel transistor (e.g., the gate electrode 24G of the AMP 24), for example, a p-type diffusion layer (p++) 16 having a higher impurity concentration than the p-type diffusion layer (p+) 15 is provided at approximately the same height as the p-type diffusion layer (p+) 15 formed at the lower portion of the element isolation portion 13. In the entire unit pixel P, a p-type diffusion layer (p++) 16 is provided along the side of the element isolation portion 14 extending in the direction (Y-axis direction) in which the RST 23, the AMP 24, and the SEL 25, and the TRG 21 and the FDG 26 are arranged side by side. This p-type diffusion layer (p++) 16 corresponds to a specific example of the "second impurity diffusion layer" of the present invention. Except for this point, the image pickup element 1B has a configuration substantially similar to that of the image pickup element 1 according to the first embodiment described above.

[0054] In this manner, in the image pickup element 1B of the present modification, a p-type diffusion layer (p++) 16 having a higher impurity concentration than the p-type diffusion layer (p+) 15 formed in the lower portion of the element isolation portion 13 is provided below the gate electrode of the pixel transistor in the vicinity of the element isolation portion 14 having the FTI structure. Therefore, even in a case where a portion of the gate electrode of the pixel transistor is buried so as not to be sufficient to form a channel region 11X having a substantially uniform depth between the element isolation portion 13 and the element isolation portion 14 as in the image pickup element 1 of the first embodiment described above, a substantially uniform channel region 11X can be formed between the element isolation portion 13 and the element isolation portion 14.

[0055] Fig. 9 The image pickup device 1B is shown along Figure 8 The cross section along the line III-III is shown in FIG. In addition, when the p-type diffusion layer (p++) 16 is provided near the element isolation portion 14 under the gate electrode of the pixel transistor that does not cause a larger amount of current to flow than the AMP 24, such as the RST 23 and the FDG 26, the channel region 11X is formed deeper on the side of the element isolation portion 14. Therefore, the potential under the transistor gate electrode of the pixel can be controlled, and the amount of charge held in the FD 22 can be controlled.

[0056] For example, Fig. 9As shown in FIG. 1 , a portion (buried portion 26X) of the gate electrode 26G of the FDG 26 is buried in the element isolation portion 13, and further, a p-type diffusion layer (p++) 16 having a higher impurity concentration than the p-type diffusion layer (p+) 15 is provided below the gate electrode 26G of the FDG 26, thereby making it possible to expand the potential range (r) when the FDG 26 is turned on / off, for example, Fig.10 Therefore, the pixel characteristics can be improved.

[0057] In addition, by burying the embedded portion 26X deeper in the element isolation portion 13, the channel region 11X is formed at the corner of the element isolation portion 13 and the gate electrode 26G. Therefore, it is possible to control the on / off of the FDG 26 at the corner. That is, it is possible to expand the potential range (r) by controlling the potential level of Si under the gate when the gate electrode 26G of the FDG 26 is closed and the potential level of Si under the gate when the gate electrode 26G is open. Therefore, it is possible to increase the amount of charge retained in the FD 22, and improve the degree of freedom of potential design. In addition, it is possible to make the channel length (W) shorter, thereby improving the degree of freedom of layout.

[0058] <4. Second Implementation Plan> Fig.11 A cross-sectional configuration of a main portion of an image pickup element (image pickup element 2 ) according to a second embodiment of the present invention is schematically shown. Fig.12 Schematically shows Fig.11 The planar structure of the imaging element 2 shown in FIG. Fig.11 Shown along Fig.12 For example, as in the first embodiment described above, the image pickup element 2 constitutes one pixel (unit pixel P) in an image pickup device 100 such as a CMOS image sensor used in electronic equipment such as a digital camera or a video camera.

[0059] In the first embodiment described above, a portion (buried portion 24X) of the gate electrodes of a plurality of pixel transistors (e.g., the gate electrode 24G of the AMP 24) is buried in the element isolation portion 13 having the STI structure. In contrast, in the image pickup element 2 of the present embodiment, in a pixel transistor having an L-shape in the active region 11A below the gate electrode, a portion (buried portion 26Y) of the gate electrode (e.g., the gate electrode 26G of the FDG 26) is buried in the element isolation portion 14 having the FTI structure. Except for this point, the image pickup element 2 has a configuration substantially similar to that of the image pickup element 1 according to the first embodiment described above.

[0060] In such Fig.12In the pixel transistor shown in which the active region 11A under the gate electrode has an L shape, the channel length is shorter inside the L shape, and the characteristics of the FDG 26 are degraded due to the short channel effect, and the characteristic variation of the pixel transistor increases.

[0061] In contrast, in the imaging element 2 of the present embodiment, a portion of the gate electrode of the pixel transistor (for example, the buried portion 26Y of the gate electrode 26G of the FDG 26) having an L-shaped active region 11A below the gate electrode is buried in the element isolation portion 14. Fig.11 As shown, the channel region 11X is formed deeper on the element isolation unit 14 side, thereby reducing the short channel effect. Therefore, it is possible to reduce the degradation of the characteristics of the pixel transistor and reduce the characteristic variation of the pixel transistor.

[0062] <5. Modification 3> Fig.13 The cross-sectional structure of the main part of the imaging element (imaging element 2A) according to the modification 3 of the present invention is schematically shown. For example, as in the above-mentioned first embodiment, the imaging element 2A constitutes one pixel (unit pixel P) in the imaging device 100 such as a CMOS image sensor used in electronic equipment such as a digital camera or a video camera.

[0063] In the above-described second embodiment, a portion (embedded portion 26Y) of the gate electrode of the pixel transistor (e.g., the gate electrode 26G of the FDG 26) having an L-shape in the active region 11A below the gate electrode is embedded in the element isolation portion 14 having the FTI structure. In contrast, in the image pickup element 2A of the present modification, the element isolation portion 13 having the STI structure and the element isolation portion 14 having the FTI structure are respectively embedded with a portion of the gate electrode (e.g., the embedded portion 26X or 26Y), and the embedded portion 26Y embedded in the element isolation portion 14 is embedded deeper than the embedded portion 24X embedded in the element isolation portion 13. Except for this point, the image pickup element 2A has a configuration substantially similar to that of the above-described image pickup element 2 according to the second embodiment.

[0064] In this way, in the imaging element 2A of this modification, the element isolation section 13 having the STI structure and the isolation region 14 having the FTI structure are respectively embedded with a portion of the gate electrode, and the embedded portion is embedded deeper in the element isolation section 14 than in the element isolation section 13. Therefore, in the case where a portion of the gate electrode is embedded in both the element isolation section 13 and the element isolation section 14, as in the above-mentioned second embodiment, the channel region 11X is formed deeper on the element isolation section 14 side, thereby reducing the short channel effect. Therefore, it is possible to reduce the degradation of the characteristics of the pixel transistor and reduce the characteristic difference of the pixel transistor.

[0065] <6. Modification 4> Fig.14 The cross-sectional configuration of the main part of the image pickup element (image pickup element 2B) according to Modification 4 of the present invention is schematically shown. For example, as in the above-described first embodiment, the image pickup element 2B constitutes one pixel (unit pixel P) in the image pickup device 100 such as a CMOS image sensor used in electronic equipment such as a digital camera or a video camera.

[0066] In the above-described second embodiment, a portion (buried portion 26Y) of the gate electrode of the pixel transistor (e.g., the gate electrode 26G of the FDG 26) having an L-shape in the active region 11A is buried in the element isolation portion 14 having the FTI structure. In contrast, in the image pickup element 2B of the present modification, a p-type diffusion layer (p++) 17 having a higher impurity concentration than the p-type diffusion layer (p+) 15 of the above-described first embodiment is provided at the lower portion of the element isolation portion 13. Except for this point, the image pickup element 2B has a configuration substantially similar to that of the above-described image pickup element 2 according to the second embodiment.

[0067] In this way, in the image pickup element 2B of this modification, a p-type diffusion layer (p++) 17 having a higher impurity concentration than the p-well is provided at the lower portion of the element isolation portion 13, thereby further reducing the short channel effect. Therefore, it is possible to further reduce the degradation of the characteristics of the pixel transistor and further reduce the characteristic variation of the pixel transistor.

[0068] Furthermore, in a pixel transistor that has an L-shape in the active region 11A below the gate electrode and does not cause a larger amount of current to flow than the AMP 24, such as the RST 23 and the FDG 26, as in the present modification, a p-type diffusion layer (p++) 17 having a high impurity concentration is provided in the lower portion of the element isolation portion 13, thereby being able to control the potential below the gate electrode of each pixel transistor and control the amount of charge held in the FD 22. For example, as Fig.14 As shown, by providing a p-type diffusion layer (p++) 17 having a higher impurity concentration than the p-well at the lower portion of the element isolation portion 13, as shown in FIG. Fig.15 As shown, for example, the potential range (r) when the FDG 26 is turned on / off can be expanded, so that the pixel characteristics can be improved.

[0069] In addition, the channel region 11X is formed at the corner of the element isolation portion 14 and the gate electrode 26G, so the on / off of the FDG 26 at the corner can be controlled, and the voltage range of CutL / H can be expanded. Therefore, the amount of charge retained in the FD 22 can be increased, and the degree of freedom of potential design is improved. In addition, the channel length (W) can be made shorter, and thus the degree of freedom of layout is improved.

[0070] It should be noted that the active area 11A of the pixel transistor is not limited to having an L shape, and may have, for example, Fig.16 In this case, by burying a portion of the gate electrode in only the element isolation portion 14 side or in both the element isolation portions 13 and 14 of the element isolation portion 13 having the STI structure and the element isolation portion 14 having the FTI structure so as to bury it deeper in the element isolation portion 14, it is also possible to obtain effects similar to those of the above-mentioned second embodiment and variation 3. In addition, by providing a p-type diffusion layer (p++) 17 at the lower portion of the element isolation portion 13, it is possible to obtain effects similar to those of the above-mentioned variation 4.

[0071] <7. Application examples> (Application example 1) For example, the imaging element 1 and the imaging device 100 including the imaging element 1 described above are applicable to various electronic devices such as imaging systems such as digital cameras or digital video cameras, mobile phones with imaging functions, and other devices with imaging functions.

[0072] Fig.17 is a block diagram showing a configuration example of the electronic device 1000 .

[0073] like Fig.17 As shown, the electronic device 1000 includes an optical system 1001, a camera device 100 and a digital signal processor (DSP) 1002, and has a structure in which the DSP 1002, a memory 1003, a display device 1004, a recording device 1005, an operating system 1006 and a power supply system 1007 are connected via a bus 1008, and is capable of capturing still images and moving images.

[0074] The optical system 1001 includes one or more lenses, and receives incident light (image light) from a subject, and forms an image on an imaging plane of the imaging device 100 .

[0075] The image pickup device 100 converts the amount of incident light formed as an image on an image pickup surface through the optical system 1001 into an electric signal on a pixel-by-pixel basis, and supplies the electric signal to the DSP 1002 as a pixel signal.

[0076] The DSP 1002 performs various signal processing on the signal from the camera 100 and obtains an image, and temporarily stores the data of the image in the memory 1003. The image data stored in the memory 1003 is recorded on the recording device 1005, or is supplied to the display device 1004 to display the image. In addition, the operating system 1006 receives various operations performed by the user and supplies operation signals to the various modules of the electronic device 1000, and the power supply system 1007 supplies power required to drive the various modules of the electronic device 1000.

[0077] (Application Example 2) Fig.18A An example of the overall configuration of a light detection system 2000 including an image pickup device (eg, the image pickup device 100 ) is schematically shown. Fig.18B An example of a circuit configuration of a light detection system 2000 is shown. The light detection system 2000 includes a light emitting device 2001 as a light source unit that emits infrared light L2 and a light detection device 2002 as a light receiving unit. For example, the above-described imaging device 100 can be used as the light detection device 2002. The light detection system 2000 may further include a system control section 2003, a light source driving section 2004, a sensor control section 2005, a light source side optical system 2006, and a camera side optical system 2007.

[0078] The light detection device 2002 can detect light L1 and light L2. Light L1 is ambient light from the outside that is emitted from the subject (object to be detected) 2100 ( Fig.18A) is reflected by the light L2. The light L2 is light emitted from the light emitting device 2001 and then reflected from the subject 2100. The light L1 is, for example, visible light, and the light L2 is, for example, infrared light. The light L1 can be detected in the photoelectric conversion section of the light detection device 2002, and the light L2 can be detected in the photoelectric conversion region of the light detection device 2002. Image information of the subject 2100 can be acquired from the light L1, and information about the distance between the subject 2100 and the light detection system 2000 can be acquired from the light L2. The light detection system 2000 can be installed in, for example, an electronic device such as a smartphone or a moving body such as a vehicle. The light emitting device 2001 can include, for example, a semiconductor laser, a surface emitting semiconductor laser, or a vertical cavity surface emitting laser (VCSEL). As a method for the light detection device 2002 to detect the light L2 emitted from the light emitting device 2001, for example, an iTOF method can be adopted; however, the method is not limited thereto. In the iTOF method, the photoelectric conversion unit can measure the distance to the subject 2100 based on, for example, the time of flight (TOF) of light. As a method in which the light detection device 2002 detects the light L2 emitted from the light emitting device 2001, for example, a structured light method and a stereoscopic vision method can also be adopted. For example, in the structured light method, a predetermined pattern of light is projected onto the subject 2100, and the distance between the light detection system 2000 and the subject 2100 can be measured by analyzing the distortion state of the pattern. In addition, in the stereoscopic vision method, two or more images of the subject 2100 observed from two or more different viewpoints are acquired using, for example, two or more cameras, so that the distance between the light detection system 2000 and the subject can be measured. It should be noted that the system control unit 2003 can synchronously control the light emitting device 2001 and the light detection device 2002.

[0079] <8. Practical application examples> (Example of actual application of endoscopic surgery system) The technology according to the present invention (the present technology) is applicable to various products. For example, the technology according to the present invention can be applied to an endoscopic surgery system.

[0080] Fig.19 : is a view showing a schematic configuration example of an endoscopic surgery system to which the technology according to the embodiment of the present invention (the present technology) can be applied.

[0081] exist Fig.19, a state is shown in which a surgeon (doctor) 11131 is using an endoscopic surgery system 11000 to perform surgery on a patient 11132 on a bed 11133. As shown in the figure, the endoscopic surgery system 11000 includes an endoscope 11100, other surgical tools 11110 (such as a pneumoperitoneum tube 11111 and an energy therapy device 11112), a support arm device 11120 (on which the endoscope 11100 is supported), and a cart 11200 (on which various devices for endoscopic surgery are loaded).

[0082] The endoscope 11100 includes a lens barrel 11101 and a camera head 11102 connected to the proximal end of the lens barrel 11101, and the lens barrel 11101 has a predetermined length from its distal end for insertion into a body cavity of a patient 11132. In the example shown, the endoscope 11100 is described as an endoscope configured as a so-called rigid endoscope having a rigid lens barrel 11101. However, the endoscope 11100 may also be configured as a flexible endoscope having a flexible lens barrel 11101.

[0083] The lens barrel 11101 has an opening at its distal end for mounting an objective lens. The light source device 11203 is connected to the endoscope 11100 so that the light generated by the light source device 11203 is guided to the distal end of the lens barrel 11101 through a light guide extending inside the lens barrel 11101 and irradiated toward an observation target in the body cavity of the patient 11132 through the objective lens. It should be noted that the endoscope 11100 may be a forward-looking endoscope, or may be an oblique-looking endoscope or a side-looking endoscope.

[0084] An optical system and an imaging element are provided inside the camera head 11102, so that the reflected light (observation light) from the observation target is focused on the imaging element by the optical system. The imaging element performs photoelectric conversion on the observation light to generate an electrical signal corresponding to the observation light, that is, an image signal corresponding to the observation image. The image signal is transmitted to the camera control unit (CCU) 11201 as raw data.

[0085] The CCU 11201 includes a central processing unit (CPU) or a graphics processing unit (GPU) or the like, and centrally controls the operations of the endoscope 11100 and the display device 11202. In addition, the CCU 11201 receives an image signal from the camera 11102, and performs various image processing for displaying an image based on the image signal, such as development processing (demosaic processing), on the image signal.

[0086] The display device 11202 displays an image based on an image signal that has been image-processed by the CCU 11201 under the control of the CCU 11201 .

[0087] The light source device 11203 includes a light source such as, for example, a light emitting diode (LED), and provides irradiation light to the endoscope 11100 when imaging a surgical area or the like.

[0088] The input device 11204 is an input interface for the endoscopic surgery system 11000. The user can input various types of information or instructions to the endoscopic surgery system 11000 through the input device 11204. For example, the user will input instructions through the endoscope 11100 to change the imaging conditions (type of irradiation light, magnification or focal length, etc.).

[0089] The treatment tool control device 11205 controls the driving of the energy treatment device 11112 for cauterizing or cutting tissue, sealing blood vessels, etc. The pneumoperitoneum device 11206 delivers gas into the body cavity of the patient 11132 through the pneumoperitoneum tube 11111 to inflate the body cavity to ensure the field of view of the endoscope 11100 and to ensure the working space of the surgeon. The recorder 11207 is a device capable of recording various types of information related to the operation. The printer 11208 is a device capable of printing various types of information related to the operation in various forms (such as text, images, or graphics).

[0090] It should be noted that the light source device 11203 that provides the irradiation light when the surgical area is to be imaged to the endoscope 11100 may include a white light source such as an LED, a laser light source, or a combination thereof. In the case where the white light source includes a combination of red, green, and blue (RGB) laser light sources, since the output intensity and output timing of each color (each wavelength) can be controlled with high precision, the white balance adjustment of the captured image can be performed by the light source device 11203. In addition, in this case, if the laser beams from each RGB laser light source are irradiated onto the observation target in a time-sharing manner, and the driving of the imaging element of the camera 11102 is controlled in synchronization with the irradiation timing, it is also possible to capture images corresponding to each of R, G, and B in a time-sharing manner. According to this method, a color image can be obtained even if a color filter is not provided for the imaging element.

[0091] In addition, the light source device 11203 can be controlled so that the intensity of the light to be output changes at predetermined intervals. By controlling the drive of the camera device of the camera 11102 in synchronization with the timing of the change in light intensity to acquire images in a time-sharing manner and synthesize these images, it is possible to create an image with a high dynamic range without underexposed shadows and overexposed highlights.

[0092] In addition, the light source device 11203 can be configured to provide light of a predetermined wavelength band that can be used for special light observation. In special light observation, for example, by utilizing the wavelength dependence of light absorption in human tissue to irradiate light of a narrower wavelength band than the irradiation light (i.e., white light) during ordinary observation, it is possible to perform narrow band light observation (Narrow Band Imaging) for imaging predetermined tissues (e.g., blood vessels on the surface of the mucosa, etc.) with high contrast. Alternatively, in special light observation, fluorescence observation for obtaining images from fluorescence generated by irradiation with excitation light can be performed. In fluorescence observation, fluorescence from body tissue can be observed by irradiating excitation light onto body tissue (autofluorescence observation), or a fluorescence image can be obtained by locally injecting a reagent such as indocyanine green (ICG) and irradiating excitation light corresponding to the fluorescence wavelength of the reagent onto human tissue. The light source device 11203 can be configured to provide narrow band light and / or excitation light suitable for the above-mentioned special light observation.

[0093] Fig. 20 It shows Fig.19 A block diagram of an example of the functional configuration of the camera 11102 and the CCU 11201 shown.

[0094] The camera 11102 includes a lens unit 11401, an imaging section 11402, a driving section 11403, a communication section 11404, and a camera control section 11405. The CCU 11201 includes a communication section 11411, an image processing section 11412, and a control section 11413. The camera 11102 and the CCU 11201 are connected to each other through a transmission cable 11400 for communication.

[0095] The lens unit 11401 is an optical system provided at a connection position with the lens barrel 11101. Observation light taken from the distal end of the lens barrel 11101 is guided to the camera head 11102 and introduced into the lens unit 11401. The lens unit 11401 includes a combination of a plurality of lenses including a zoom lens and a focus lens.

[0096] The number of imaging elements included in the imaging unit 11402 may be one (single-board type) or multiple (multi-board type). For example, in the case where the imaging unit 11402 is configured as a multi-board type, image signals corresponding to each of R, G, and B are generated by the imaging element, and these image signals can be synthesized to obtain a color image. The imaging unit 11402 may also be constructed to have a pair of imaging elements for respectively acquiring image signals for the right eye and for the left eye, thereby being used for three-dimensional (3D) display. If 3D display is performed, the surgeon 11131 can more accurately understand the depth of living tissue in the surgical area. It should be noted that in the case where the imaging unit 11402 is configured as a multi-board type imaging unit, multiple systems of lens units 11401 are provided corresponding to the respective imaging elements.

[0097] In addition, the imaging unit 11402 does not have to be provided on the camera head 11102. For example, the imaging unit 11402 may be provided inside the lens barrel 11101 immediately behind the objective lens.

[0098] The driving section 11403 includes an actuator, and moves the zoom lens and the focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera control section 11405. Therefore, the magnification and focus of the image captured by the imaging section 11402 can be appropriately adjusted.

[0099] The communication section 11404 includes a communication device for transmitting and receiving various types of information to and from the CCU 11201. The communication section 11404 transmits an image signal acquired from the imaging section 11402 to the CCU 11201 as RAW data via the transmission cable 11400.

[0100] In addition, the communication unit 11404 receives a control signal for controlling the driving of the camera 11102 from the CCU 11201, and provides the control signal to the camera control unit 11405. The control information includes, for example, information related to imaging conditions, such as information specifying a frame rate of an image to be captured, information specifying an exposure value during imaging, and / or information specifying a magnification and a focus of an image to be captured.

[0101] It should be noted that imaging conditions such as frame rate, exposure value, magnification, or focus may be specified by a user or may be automatically set based on an acquired image signal by the control unit 11413 of the CCU 11201. In the latter case, the endoscope 11100 includes an automatic exposure (AE) function, an automatic focus (AF) function, and an automatic white balance (AWB) function.

[0102] The camera control unit 11405 controls the driving of the camera 11102 based on the control signal received from the CCU 11201 through the communication unit 11404 .

[0103] The communication section 11411 includes a communication device for sending various types of information to the camera 11102 and receiving various types of information from the camera 11102. Through the transmission cable 11400, the communication section 11411 receives an image signal sent thereto from the camera 11102.

[0104] In addition, the communication unit 11411 transmits a control signal for controlling the driving of the camera 11102 to the camera 11102. The image signal and the control signal can be transmitted through electrical communication, optical communication, or the like.

[0105] The image processing unit 11412 performs various image processing on the image signal in the form of RAW data sent thereto from the camera 11102 .

[0106] The control unit 11413 performs various types of control related to the imaging of the operation area, etc. by the endoscope 11100 and the display of the captured image obtained by imaging the operation area, etc. For example, the control unit 11413 generates a control signal for controlling the driving of the camera head 11102 .

[0107] In addition, the control unit 11413 controls the display device 11202 to display a captured image of the surgical area, etc., based on the image signal that has been image-processed by the image processing unit 11412. Therefore, the control unit 11413 can use various image recognition technologies to recognize various objects in the captured image. For example, the control unit 11413 can recognize surgical tools such as forceps, specific living body areas, bleeding, fog when the energy treatment device 11112 is used, etc. by detecting the shape, color, etc. of the edge of the object contained in the captured image. When the control unit 11413 controls the display device 11202 to display the captured image, the control unit 11413 can use the recognition result to display various types of surgical support information in a manner that overlaps with the image of the surgical area. When the surgical support information is displayed in an overlapping manner and presented to the surgeon 11131, the burden on the surgeon 11131 can be reduced, and the surgeon 11131 can perform the operation with confidence.

[0108] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 to each other is an electric signal cable capable of being used for electric signal communication, an optical fiber capable of being used for optical communication, or a composite cable capable of being used for electric communication and optical communication.

[0109] Here, although in the illustrated example, communication is performed by wired communication using the transmission cable 11400, communication between the camera 11102 and the CCU 11201 may be performed by wireless communication.

[0110] As described above, an example of an endoscopic surgery system to which the technology according to the present invention can be applied has been described. The technology according to the present invention can be applied to the imaging unit 11402 among the above components. By applying the technology according to the present invention to the imaging unit 11402, the detection accuracy can be improved.

[0111] It should be noted that, here, an endoscopic surgery system has been described as an example; however, the technology according to the present invention can be applied to other systems, such as a microsurgery system and the like.

[0112] (Example of actual application on mobile objects) The technology according to the present invention is applicable to various products. For example, the technology according to the present invention can be implemented as a device installed on any type of mobile body such as automobiles, electric vehicles, hybrid vehicles, motorcycles, bicycles, personal transportation vehicles, airplanes, drones, ships, robots, construction equipment, and agricultural machinery (tractors).

[0113] Fig.21 : is a block diagram showing an example of a schematic configuration of a vehicle control system as an example of a moving body control system to which the technology according to the embodiment of the present invention can be applied.

[0114] The vehicle control system 12000 includes a plurality of electronic control units connected to each other via a communication network 12001. Fig.21 In the example shown, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an external information detection unit 12030, an internal information detection unit 12040, and an integrated control unit 12050. In addition, as the functional configuration of the integrated control unit 12050, a microcomputer 12051, a sound and image output unit 12052, and an in-vehicle network interface (I / F) 12053 are shown.

[0115] The drive system control unit 12010 controls the operation of devices related to the drive system of the vehicle according to various types of programs. For example, the drive system control unit 12010 serves as a control device for the following devices: a drive force generating device such as an internal combustion engine or a drive motor for generating a vehicle drive force, a drive force transmitting 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 vehicle braking force.

[0116] The body system control unit 12020 controls the operation of various types of devices provided on the vehicle body according to various types of programs. For example, the body system control unit 12020 is used as a control device for a keyless entry system, a smart key system, a power window device, or various lights such as a headlight, a reverse light, a brake light, a turn signal light, or a fog light. In this case, a radio wave transmitted from a mobile device that replaces the key or a signal of various types of switches may be input to the body system control unit 12020. The body system control unit 12020 receives input of these radio waves or signals, and controls a door lock device, a power window device, or a light, etc. of the vehicle.

[0117] The vehicle exterior information detection unit 12030 detects information outside the vehicle including the vehicle control system 12000. For example, the vehicle exterior information detection unit 12030 is connected to the camera unit 12031. The vehicle exterior information detection unit 12030 causes the camera unit 12031 to capture an image of the vehicle exterior and receives the captured image. Based on the received image, the vehicle exterior information detection unit 12030 can perform detection processing of objects such as people, vehicles, obstacles, signs, or characters on the road surface, or can perform detection processing of the distance to the above-mentioned objects.

[0118] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image, or can output the electrical signal as distance measurement information. In addition, the light received by the imaging unit 12031 can be visible light, or can be invisible light such as infrared rays.

[0119] The in-vehicle information detection unit 12040 detects information about the interior of the vehicle. The in-vehicle information detection unit 12040 is connected to, for example, a driver state detection unit 12041 that detects the driver's state. The driver state detection unit 12041 includes, for example, a camera that takes a picture of the driver. Based on the detection information input from the driver state detection unit 12041, the in-vehicle information detection unit 12040 can calculate the driver's fatigue level or the driver's concentration level, or can determine whether the driver is dozing off.

[0120] The microcomputer 12051 can calculate the control target value of the driving force generating device, the steering mechanism or the braking device based on the information outside or inside the vehicle obtained by the vehicle outside information detection unit 12030 or the vehicle inside information detection unit 12040, and output the control command to the driving system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of the advanced driver assistance system (ADAS), including collision avoidance or impact mitigation of the vehicle, following driving based on the vehicle-to-vehicle distance, speed maintenance driving, vehicle collision warning or vehicle lane departure warning, etc.

[0121] In addition, by controlling the driving force generating device, steering mechanism or braking device, etc. based on the information outside or inside the vehicle obtained by the external information detection unit 12030 or the internal information detection unit 12040, the microcomputer 12051 can perform collaborative control aimed at achieving automatic driving, etc., wherein the automatic driving enables the vehicle to drive autonomously without relying on the driver's operation.

[0122] In addition, based on the information outside the vehicle obtained by the vehicle exterior information detection unit 12030, the microcomputer 12051 can output a control command to the body system control unit 12020. For example, the microcomputer 12051 can perform cooperative control aimed at preventing glare by controlling the headlights to change from high beam to low beam, for example, according to the position of the preceding vehicle or the oncoming vehicle detected by the vehicle exterior information detection unit 12030.

[0123] The audio and video output unit 12052 sends an output signal of at least one of audio and video to an output device capable of visually or auditorily notifying the vehicle's passengers or the outside of the vehicle of the information. Fig.21 In the example of , as the output device, an audio speaker 12061, a display portion 12062, and an instrument panel 12063 are shown. For example, the display portion 12062 may include at least one of an in-vehicle display and a head-up display.

[0124] Fig. 22 12031 is a diagram showing an example of the installation position of the camera unit 12031.

[0125] exist Fig. 22 In the figure, the camera unit 12031 includes camera units 12101, 12102, 12103, 12104 and 12105.

[0126] The camera units 12101, 12102, 12103, 12104 and 12105 are, for example, arranged at the front nose, rearview mirror, rear bumper and rear door of the vehicle 12100 and at the upper part of the windshield in the vehicle compartment. The camera unit 12101 arranged at the front nose and the camera unit 12105 arranged at the upper part of the windshield in the vehicle compartment mainly obtain images in front of the vehicle 12100. The camera units 12102 and 12103 arranged at the rearview mirror mainly obtain images on both sides of the vehicle 12100. The camera unit 12104 arranged at the rear bumper or rear door mainly obtains images behind the vehicle 12100. The camera unit 12105 arranged at the upper part of the windshield in the vehicle compartment is mainly used to detect the vehicle in front, pedestrians, obstacles, traffic lights, traffic signs or lanes, etc.

[0127] By the way, Fig. 22An example of the imaging range of the imaging units 12101 to 12104 is shown. The imaging range 12111 indicates the imaging range of the imaging unit 12101 provided at the front nose. The imaging ranges 12112 and 12113 respectively indicate the imaging ranges of the imaging units 12102 and 12103 provided at the rearview mirror. The imaging range 12114 indicates the imaging range of the imaging unit 12104 provided at the rear bumper or the rear door. For example, by superimposing the image data captured by the imaging units 12101 to 12104, a bird's-eye view image of the vehicle 12100 observed from above is obtained.

[0128] At least one of the imaging units 12101 to 12104 may have a function of obtaining distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera composed of a plurality of imaging elements, or may be an imaging element having pixels for phase difference detection.

[0129] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can determine the distance of each three-dimensional object within the imaging ranges 12111 to 12114 and the time change of the distance (relative speed with respect to the vehicle 12100), thereby extracting the nearest three-dimensional object as the leading vehicle, in particular, the three-dimensional object that exists on the driving path of the vehicle 12100 and travels in the same direction as the vehicle 12100 at a predetermined speed (e.g., equal to or greater than 0 km / h). In addition, the microcomputer 12051 can pre-set the inter-vehicle distance to be maintained with the leading vehicle, and perform automatic braking control (including follow-up stop control) or automatic acceleration control (including follow-up start control), etc. Therefore, it is possible to perform cooperative control such as automatic driving that aims to make the vehicle travel autonomously without relying on the operation of the driver.

[0130] For example, based on the distance information obtained from the camera units 12101 to 12104, the microcomputer 12501 can classify the three-dimensional object data of the three-dimensional object into three-dimensional object data of two-wheeled vehicles, standard vehicles, large vehicles, pedestrians, telephone poles and other three-dimensional objects, extract the classified three-dimensional object data, and use the extracted three-dimensional object data to automatically avoid obstacles. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 as obstacles that the driver of the vehicle 12100 can visually identify and obstacles that the driver of the vehicle 12100 is difficult to visually identify. Then, the microcomputer 12051 determines a collision risk indicating the degree of risk of collision with each obstacle. In the case where the collision risk is equal to or higher than the set value and therefore there is a possibility of collision, the microcomputer 12051 outputs a warning to the driver via the audio speaker 12061 or the display unit 12062, and performs forced deceleration or evasive steering via the drive system control unit 12010. Therefore, the microcomputer 12051 can assist driving to avoid collisions.

[0131] At least one of the camera units 12101 to 12104 may be an infrared camera that detects infrared rays. The microcomputer 12051 is capable of identifying pedestrians, for example, by determining whether there are pedestrians in the camera images of the camera units 12101 to 12104. For example, such identification of pedestrians is performed by the following steps: a step of extracting feature points in the camera images of the camera units 12101 to 12104 as infrared cameras; and a step of performing pattern matching processing on a series of feature points representing the contour of an object to determine whether it is a pedestrian. If the microcomputer 12051 determines that there are pedestrians in the camera images of the camera units 12101 to 12104 and thus identifies the pedestrian, the sound image output unit 12052 controls the display unit 12062 so that a square contour line for emphasis is displayed in a manner superimposed on the identified pedestrian. The sound image output unit 12052 may also control the display unit 12062 so that an icon representing a pedestrian or the like is displayed at a desired position.

[0132] As above, an example of a mobile body control system to which the technology according to the present invention can be applied has been described. The technology according to the present invention can be applied to, for example, the imaging unit 12031 among the above-mentioned components. Specifically, the imaging element (for example, the imaging element 1A) according to the above-mentioned embodiment and its modified example is applicable to the imaging unit 12031. By applying the technology according to the present invention to the imaging unit 12031, a high-definition image with less noise can be obtained; therefore, the image can be used for high-precision control in the mobile body control system.

[0133] The present technology has been described above by means of the first and second embodiments, modification examples 1 to 4, and applicable examples and practical application examples; however, the content of the present invention is not limited to the above-described embodiments, etc., and various modifications can be made. For example, between the n-type semiconductor region (n) constituting the photoelectric conversion unit 12 and the element isolation unit 14, a p-type diffusion region (p+) having a high p-type impurity concentration can be formed.

[0134] Furthermore, in the above-described embodiments and the like, a configuration example of a back-illuminated image pickup element is provided; however, the contents of the present invention are also applicable to a front-illuminated image pickup element.

[0135] In addition, the camera device 100 and the electronic device 1000 of the present invention do not necessarily include all the components described in the above embodiments, etc., but may include other components. For example, the electronic device 1000 may be provided with a shutter for controlling light entering the camera device 100, and may include an optical cutoff filter according to the purpose of the electronic device 1000.

[0136] It should be noted that the effects described in this specification are merely examples, the effects of the present invention are not limited thereto, and the present invention may have other effects.

[0137] It should be noted that the present technology may have the following configuration. According to the present technology having the following configuration, by burying a portion of the gate electrode of one or more pixel transistors at different depths in at least one of a first element isolation portion and a second element isolation portion having different depths from each other and provided in a semiconductor substrate and defining an active region of the one or more pixel transistors, the shape of the channel region formed under the gate electrode is controlled. Therefore, it is possible to improve image quality. (1) A camera element, comprising: a semiconductor substrate including a photoelectric conversion portion of each pixel; One or more pixel transistors disposed in one surface of the semiconductor substrate; and a first element isolation portion and a second element isolation portion having different depths from each other, which are buried in the one surface of the semiconductor substrate and define active regions of the one or more pixel transistors, Part of the gate electrode of the one or more pixel transistors is buried at different depths in at least one of the first element isolation portion and the second element isolation portion. (2) The imaging element according to the above (1), wherein the depth of the first element isolation portion is shallower than the depth of the second element isolation portion. (3) In the imaging element described in (1) or (2) above, the gate electrode includes a first embedded portion embedded in the first element isolation portion. (4) The imaging device according to any one of (1) to (3) above, wherein The gate electrode has a first buried portion buried in the first element isolating portion and a second buried portion buried in the second element isolating portion, and The first embedded portion has a depth deeper than that of the second embedded portion. (5) The imaging element according to any one of (1) to (4) above, wherein the impurity concentration under the gate electrode is higher on the second element isolation portion side than on the first element isolation portion side. (6) According to the imaging element described in (5) above, the semiconductor substrate further includes a first impurity diffusion layer and a second impurity diffusion layer, the first impurity diffusion layer is arranged at the lower part of the first element isolation part and has a higher impurity concentration than the well area of ​​the semiconductor substrate, and the second impurity diffusion layer is arranged at a position closer to the second element isolation part and has a higher impurity concentration than the first impurity diffusion layer. (7) The imaging element according to any one of (1) to (6), wherein the channel region formed in the active region below the gate electrode is formed between the first element isolation portion and the second element isolation portion at substantially the same depth. (8) The imaging element according to (6) or (7) above, wherein the channel region formed in the active region below the gate electrode is formed deeper on the first element isolation portion side. (9) The imaging device according to any one of (1) to (8) above, wherein the active region has an L-shape or a U-shape. (10) The imaging element according to the above (9), wherein the gate electrode has a second embedded portion embedded in the second element isolation portion. (11) The imaging device according to (9) or (10) above, wherein The gate electrode has a first embedded portion embedded in the first element isolation portion and a second embedded portion embedded in the second element isolation portion, and The second embedded portion has a depth greater than that of the first embedded portion. (12) The imaging element according to any one of (9) to (11) above, wherein the impurity concentration below the gate electrode is higher on the first element isolation portion side than on the second element isolation portion side. (13) The imaging element according to any one of (9) to (12), wherein the channel region formed in the active region below the gate electrode is formed deeper on the second element isolation portion side. (14) An electronic device comprising an imaging element, The imaging element comprises: a semiconductor substrate including a photoelectric conversion portion of each pixel; One or more pixel transistors disposed in one surface of the semiconductor substrate; and a first element isolation portion and a second element isolation portion having different depths from each other, which are buried in the one surface of the semiconductor substrate and define active regions of the one or more pixel transistors, Part of the gate electrode of the one or more pixel transistors is buried at different depths in at least one of the first element isolation portion and the second element isolation portion.

[0138] This application claims priority from Japanese Patent Application JP2022-147341 filed with the Japan Patent Office on September 15, 2022, the entire contents of which are incorporated herein by reference.

[0139] It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made according to design requirements and other factors as long as they are within the scope of the appended claims or their equivalents.

Claims

1. An imaging element, comprising: a semiconductor substrate including a photoelectric conversion portion of each pixel; one or more pixel transistors disposed in a surface of the semiconductor substrate; as well as a first element isolation portion and a second element isolation portion having different depths from each other, which are buried in the one surface of the semiconductor substrate and define active regions of the one or more pixel transistors, Part of the gate electrode of the one or more pixel transistors is buried at different depths in at least one of the first element isolation portion and the second element isolation portion. 2 . The image pickup element according to claim 1 , wherein a depth of the first element isolating portion is shallower than a depth of the second element isolating portion. 3 . The image pickup element according to claim 1 , wherein the gate electrode has a first embedded portion embedded in the first element isolation portion.

4. The imaging element according to claim 1, wherein The gate electrode has a first embedded portion embedded in the first element isolation portion and a second embedded portion embedded in the second element isolation portion, and The first embedded portion has a depth deeper than that of the second embedded portion. 5 . The image pickup element according to claim 1 , wherein an impurity concentration under the gate electrode is higher on the second element isolation portion side than on the first element isolation portion side.

6. An imaging element according to claim 5, wherein the semiconductor substrate further comprises a first impurity diffusion layer and a second impurity diffusion layer, the first impurity diffusion layer being arranged at a lower portion of the first element isolation portion and having a higher impurity concentration than a well region of the semiconductor substrate, and the second impurity diffusion layer being arranged at a position closer to the second element isolation portion and having a higher impurity concentration than the first impurity diffusion layer. 7 . The image pickup element according to claim 1 , wherein a channel region formed in the active region below the gate electrode is formed between the first element isolation portion and the second element isolation portion at substantially the same depth. 8 . The image pickup element according to claim 6 , wherein a channel region formed in the active region below the gate electrode is formed deeper on the first element isolation portion side. 9 . The image sensor according to claim 1 , wherein the active region has an L-shape or a U-shape. 10 . The image pickup element according to claim 9 , wherein the gate electrode has a second embedded portion embedded in the second element isolating portion.

11. The imaging element according to claim 9, wherein The gate electrode has a first embedded portion embedded in the first element isolation portion and a second embedded portion embedded in the second element isolation portion, and The second embedded portion has a depth greater than that of the first embedded portion. 12 . The image pickup element according to claim 9 , wherein an impurity concentration below the gate electrode is higher on the first element isolation portion side than on the second element isolation portion side. 13 . The image pickup element according to claim 9 , wherein a channel region formed in the active region below the gate electrode is formed deeper on the second element isolation portion side.

14. An electronic device comprising an imaging element, The imaging element comprises: a semiconductor substrate including a photoelectric conversion portion of each pixel; one or more pixel transistors disposed in a surface of the semiconductor substrate; and a first element isolation portion and a second element isolation portion having different depths from each other, which are buried in the one surface of the semiconductor substrate and define active regions of the one or more pixel transistors, Part of the gate electrode of the one or more pixel transistors is buried at different depths in at least one of the first element isolation portion and the second element isolation portion.

Images