Photodetectors, X-ray imaging sensors, and electronic equipment

Abstract

A first light-receiving element (1) according to one embodiment of the present disclosure is provided with: a semiconductor substrate (11) including a photoelectric conversion region; a first first-conductivity-type region (13A) that is provided at the interface of a first surface (S1) of the semiconductor substrate (11) and that is connected to a first electrode (16); a second first-conductivity-type region (13B) that is provided, in the interface of the first surface (S1), at the periphery of the first first-conductivity-type region (13A) and that is connected to a second electrode (17); a third first-conductivity-type region (13C) that is provided, in the interface of the first surface (S1), at the periphery of the second first-conductivity-type region (13B) and that is electrically floating; a first second-conductivity-type region (21) that is provided in the interface of the first surface (S1) at a portion between the first first-conductivity-type region (13A) and the second first-conductivity-type region (13B) and that has a different conductivity type; and fourth first-conductivity-type regions (22) that are provided near the interface of the first surface (S1), at least between the first first-conductivity-type region (13A) and the first second-conductivity-type region (21) and that have an impurity concentration lower than that of the first first-conductivity-type region (13A).

Description

[Technical Field]

[0001] This disclosure relates to a photodetector suitable for, for example, X-ray imaging for medical or non-destructive testing purposes, as well as an X-ray imaging sensor and electronic equipment equipped therewith. [Background technology]

[0002] Solid-state imaging devices (Solid State Imaging Devices) are used in a variety of applications, such as imaging devices in digital still cameras and video cameras, electronic devices such as mobile terminals with imaging capabilities, and electromagnetic wave sensors that detect various wavelengths other than visible light. Solid State Imaging Devices include Active Pixel Sensors (APS) equipped with an amplification element for each pixel, which store data in a photodiode, a photoelectric conversion element. The generated signal charge is read out via a MOS (Metal Oxide Semiconductor) transistor. CMOS (complementary MOS) image sensors (CIS) are widely used.

[0003] In sensors for scientific applications requiring high-sensitivity measurement, photodetectors (PIN photodiodes) with an integrated structure of a photoelectric conversion region and a floating diffusion (FD) region are used (see, for example, Patent Document 1). Such photodetectors are easy to manufacture due to their simple structure. Furthermore, an arbitrary potential difference can be applied to the pn junction forming the photoelectric conversion region. This makes it easy to increase the thickness of the photoelectric conversion region. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-4012 [Overview of the project]

[0005] Incidentally, the light-receiving element used in the X-ray imaging device is required to reduce the influence of the total dose effect due to X-ray irradiation.

[0006] It is desirable to provide a light-receiving element, an X-ray imaging device, and an electronic device capable of reducing the influence of the total dose effect due to X-ray irradiation.

[0007] The first light-receiving element according to an embodiment of the present disclosure includes a semiconductor substrate including a photoelectric conversion region, a first first-conductivity-type region provided at an interface of a first surface of the semiconductor substrate and connected to a first electrode, a second first-conductivity-type region provided around the first first-conductivity-type region at the interface of the first surface and connected to a second electrode, a third first-conductivity-type region provided around the second first-conductivity-type region at the interface of the first surface and being electrically floating, a first second-conductivity-type region having a different conductivity type provided between the first first-conductivity-type region and the second first-conductivity-type region at the interface of the first surface, and a fourth first-conductivity-type region provided at least between the first first-conductivity-type region and the first second-conductivity-type region in the vicinity of the interface of the first surface and having an impurity concentration lower than that of the first first-conductivity-type region.

[0012] According to an embodiment of the present disclosure 2ndThe light-receiving element comprises a semiconductor substrate including a photoelectric conversion region; a first first conductivity type region provided at the interface of a first surface of the semiconductor substrate and connected to a first electrode; a second first conductivity type region provided around the first first conductivity type region at the interface of the first surface and connected to a second electrode; a third first conductivity type region provided around the second first conductivity type region at the interface of the first surface and electrically floating; a conductive film provided above the first surface, at least between the first first conductivity type region and the second first conductivity type region; a first second conductivity type region with a different conductivity type provided between the first first conductivity type region and the second first conductivity type region at the interface of the first surface; and a fourth first conductivity type region with a lower impurity concentration than the second first conductivity type region, provided between the second first conductivity type region and the first second conductivity type region at the interface of the first surface, with a portion extending over the second first conductivity type region.

[0013] One embodiment of the present disclosure Third The light-receiving element comprises a semiconductor substrate including a photoelectric conversion region, a first first conductivity type region provided at the interface of a first surface of the semiconductor substrate and connected to a first electrode, a second first conductivity type region provided around the first first conductivity type region at the interface of the first surface and connected to a second electrode, a third first conductivity type region provided around the second first conductivity type region at the interface of the first surface and in an electrically floating state, and a first surface between the first first conductivity type region and the second first conductivity type region. The device comprises a conductive film provided above, a first first conductivity type region and a second first conductivity type region formed at the interface of the first surface, between the first first conductivity type region and the second first conductivity type region, extending to a deeper position than the second first conductivity type region and having a different conductivity type, and a fourth first conductivity type region provided at the interface of the first surface between the first first conductivity type region and the second first conductivity type region and between the second first conductivity type region and the first second conductivity type region, and having a lower impurity concentration than the second first conductivity type region.

[0014] An X-ray imaging sensor according to one embodiment of the present disclosure comprises a plurality of photodetectors according to the above embodiment of the present disclosure, which generate signal charges based on X-rays.

[0015] An electronic device according to one embodiment of the present disclosure is equipped with an X-ray imaging sensor according to the above embodiment of the present disclosure.

[0016] In a first photodetector, an X-ray image sensor, and an electronic device according to one embodiment of the present disclosure, a first second conductivity type region with a different conductivity type is provided between a first first conductivity type region connected to a first electrode and a second first conductivity type region connected to a second electrode, both located near the interface of a first surface of a semiconductor substrate including a photoelectric conversion region. Furthermore, a fourth first conductivity type region with a lower impurity concentration than the first conductivity type region is provided between the first first conductivity type region and the first second conductivity type region. Book One embodiment of the disclosure 2nd In the photodetector, at the first interface of the semiconductor substrate, a first second conductivity type region is provided between a first first conductivity type region and a second first conductivity type region, and a fourth first conductivity type region is provided between the second first conductivity type region and the first second conductivity type region, with a lower impurity concentration than the second first conductivity type region, and a portion of which extends over the second first conductivity type region. One embodiment of the present disclosure Third In the photodetector, at the interface of the first surface, a first second conductivity type region is formed between the first first conductivity type region and the second first conductivity type region, extending to a deeper position than the second first conductivity type region, and a fourth first conductivity type region is provided between the first first conductivity type region and the second first conductivity type region, and between the second first conductivity type region and the first second conductivity type region, and has a lower impurity concentration than the second first conductivity type region. This reduces the formation of the second conductivity type at the interface of the first surface of the semiconductor substrate after X-ray irradiation. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic cross-sectional view showing an example of the configuration of a light-receiving element according to an embodiment of the present disclosure. [Figure 2] Figure 1 is a schematic plan view showing an example of the pattern of each conductivity type region on the surface of the semiconductor substrate of the photodetector shown in Figure 1. [Figure 3]Figure 1 is a schematic diagram illustrating an example of power supply connection to the n-type conductive region of the photodetector shown. [Figure 4] Figure 1 is a schematic diagram illustrating another example of power supply connection to the n-type conductive region of the photodetector shown in Figure 1. [Figure 5A] This figure illustrates the state before and after X-ray irradiation when an n-type conductive region is provided around the anode as a comparative example. [Figure 5B] This figure illustrates the state before and after X-ray irradiation when an n-type conductive region is provided around the anode as a comparative example. [Figure 6A] This figure illustrates the state before and after X-ray irradiation when an LDA is placed between the anode and the n-type conductive region of the photodetector shown in Figure 1. [Figure 6B] This figure illustrates the state before and after X-ray irradiation when an LDA is placed between the anode and the n-type conductive region of the photodetector shown in Figure 1. [Figure 7] This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 1 of this disclosure. [Figure 8] This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 2 of this disclosure. [Figure 9] This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 3 of this disclosure. [Figure 10] Figure 9 is a schematic cross-sectional view showing the configuration of the main parts of the light-receiving element. [Figure 11] Figure 9 is a schematic plan view illustrating an example of the gate electrode layout of a photodetector shown in Figure 9. [Figure 12] Figure 9 is a schematic plan view illustrating another example of the gate electrode layout of the photodetector shown. [Figure 13] This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 4 of this disclosure. [Figure 14] This is a schematic cross-sectional diagram showing another example of the configuration of the main components of the photodetector shown in Figure 13. [Figure 15] This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 5 of this disclosure. [Figure 16A]Figure 15 is a schematic plan view illustrating an example of the configuration of the field plate of the photodetector. [Figure 16B] This is a schematic plan view illustrating another example of the configuration of the photodetector according to Modification 5 of this disclosure. [Figure 17] Figure 16B is a schematic cross-sectional view showing an example of the configuration of the field plate of the photodetector. [Figure 18] This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 6 of this disclosure. [Figure 19] This is a schematic cross-sectional view showing another example of the configuration of the photodetector according to Modification 6 of this disclosure. [Figure 20] This is a schematic cross-sectional view showing another example of the configuration of the photodetector according to Modification 6 of this disclosure. [Figure 21] This is a schematic cross-sectional view showing another example of the configuration of the photodetector according to Modification 6 of this disclosure. [Figure 22] This is a schematic cross-sectional view showing another example of the configuration of the photodetector according to Modification 6 of this disclosure. [Figure 23] This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 7 of this disclosure. [Figure 24] Figure 23 is a schematic plan view illustrating an example of the wiring layout of the photodetector shown. [Figure 25] Figure 23 shows the surface potential depending on the position of the photodetector. [Figure 26] This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 8 of this disclosure. [Figure 27] Figure 26 is a schematic plan view illustrating an example of the layout of the photodetector shown. [Figure 28] This is a schematic plan view showing another example of the configuration of the photodetector according to Modification 8 of this disclosure. [Figure 29] This is a schematic plan view illustrating another example of the photodetector layout shown in Figure 28. [Figure 30] This is a schematic plan view illustrating another example of the photodetector layout shown in Figure 28. [Figure 31] This is a schematic plan view showing an example of the configuration of a photodetector according to Modification 9 of this disclosure. [Figure 32] This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 10 of this disclosure. [Figure 33] This is a schematic cross-sectional view showing another example of the configuration of a photodetector according to Modification 10 of this disclosure. [Figure 34] This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 11 of this disclosure. [Figure 35] This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 12 of this disclosure. [Figure 36] Figure 35 is a schematic plan view illustrating an example of the layout of the widened portion of the light-receiving element. [Figure 37A] This is a schematic plan view illustrating another example of the layout of the widened portion of the light-receiving element shown in Figure 35. [Figure 37B] This is a schematic plan view illustrating another example of the layout of the widened portion of the light-receiving element shown in Figure 35. [Figure 38] This is a schematic cross-sectional view showing an example of the configuration of the main part of the light-receiving element according to Modification 13 of this disclosure. [Figure 39] This is a schematic cross-sectional view showing another example of the configuration of the main part of the light-receiving element according to Modification 13 of this disclosure. [Figure 40] This is a schematic cross-sectional view showing another example of the configuration of the main part of the light-receiving element according to Modification 13 of this disclosure. [Figure 41] This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 14 of this disclosure. [Figure 42] This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 15 of this disclosure. [Figure 43] This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 16 of this disclosure. [Figure 44] This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to Modification 17 of this disclosure. [Figure 45] This is a block diagram showing the configuration of an X-ray imaging sensor. [Figure 46] Figure 45 is a block diagram showing a detailed configuration example of the column selection section. [Modes for carrying out the invention]

[0018] The embodiments described below will be explained in detail with reference to the drawings. The following description is one specific example of the disclosure, and the disclosure is not limited to the following embodiments. Furthermore, the disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc., of each component shown in each drawing. The order of explanation is as follows. 1. Embodiment (Example of a photodetector in which an n-type conductive region and LDA are provided on the surface of a semiconductor substrate between the anode and the drain) 1-1. Configuration of the light-receiving element 1-2. Method for manufacturing a light-receiving element 1-3. Action and Effects 2. Variations 2-1. Modification Example 1 (Example of an insulating layer between the surface of a semiconductor substrate and the wiring layer) 2-2. Modified Example 2 (Example of an insulating layer on the surface of a semiconductor substrate) 2-3. Modification Example 3 (Example of gate electrode layout) 2-4. Modification 4 (Example in which a gap is provided on the surface between the anode and the n-type conductive region) 2-5. Modification 5 (Example with a field plate above the guard ring) 2-6. Modification 6 (Example in which n-type conductive regions are provided between the drain and the guard ring and between the guard rings) 2-7. Modification 7 (Example of controlling the spacing between the semiconductor substrate surface and the wiring layer) 2-8. Modification 8 (Example in which an n-type or p-type conductive region is provided between guard rings between adjacent pixels) 2-9. Modification 9 (Example of applying voltage to the guard ring) 2-10. Modification 10 (Example in which a gap is provided between the p-type conductive region on the surface of the semiconductor substrate and the embedded layer) 2-11. Modification 11 (Example where the overlap with the drain in the widened part of the anode is omitted) 2-12. Modification 12 (Example with a partially widened section) 2-13. Modification 13 (Another example of the layout of the n-type conductive region and LDD between the anode and drain) 2-14. Modification 14 (Example of multi-step impurity concentration in the n-type conductivity region between the anode and drain) 2-15. Modification 15 (Example in which an insulating film is embedded between the anode and the drain) 2-16. Modification 16 (Example in which a gate electrode is embedded between the anode and drain) 2-17. Modification 17 (Example in which the gate of a vertical transfer transistor is embedded around the anode) 3. Examples of application

[0019] <1. Embodiment> Figure 1 schematically shows an example of the cross-sectional configuration of a light-receiving element (light-receiving element 1) according to one embodiment of the present disclosure. The light-receiving element 1 is, for example, a PIN (Positive Intrinsic Negative) type photodiode that applies a reverse bias between the front and back surfaces of a semiconductor substrate 11. For example, it constitutes a single pixel (unit pixel P) in a radiation image sensor (e.g., X-ray image sensor 100; see Figure 45) or an electromagnetic wave detection device that reads information about a subject based on radiation (e.g., alpha rays, beta rays, gamma rays, and X-rays, etc.) to image the subject.

[0020] (1-1. Configuration of the photodetector) The photodetector 1 has, for example, a p-type conductivity region (first conductivity region) 13 partially formed at the interface of the surface S1 (first surface) of an n-type semiconductor substrate 11, and an n-type conductivity layer (second conductivity layer) 12 formed at the interface of the surface opposite to the surface S1 (back surface S2; second surface). The p-type conductivity region 13 consists of multiple regions, and the photodetector 1 has, for example, a region constituting the anode 13A (first first conductivity region), a region constituting the drain 13B (second first conductivity region), and a region constituting the guard ring 13C (third first conductivity region). The photodetector 1 also has an n-type conductivity region (second conductivity region) formed as an embedded layer 14 inside the semiconductor substrate 11. The light-receiving element 1 of this embodiment further includes an n-type conductivity region (first second conductivity region) 21 at the interface of the surface S1 between the anode 13A and the drain 13B, and a Lightly Doped region between at least the anode 13A and the n-type conductivity region 21. Anode(LDA)22 has a p-type conductivity region (a fourth first conductivity region) with a lower impurity concentration than the region constituting anode 13A, etc.

[0021] In this embodiment, we will describe the case in which the holes among the excitons (electron-hole pairs) generated by photoelectric conversion are read out as the signal charge. Also, in the figure, the "-" (minus) attached to "p" and "n" indicates a low concentration of p-type or n-type impurities, and the "+" (plus) indicates a high concentration of p-type or n-type impurities. The relative magnitudes of the p-type and n-type impurities are as follows: - <p<p + ,n - <n<n + That is the case.

[0022] The semiconductor substrate 11 is composed of, for example, an n-type, p-type, or i-type (intrinsic semiconductor) semiconductor and has a pn junction or pin junction inside which the photoelectric conversion region is located. Specifically, in this embodiment, an n-type semiconductor substrate is used as the semiconductor substrate 11, and as described above, a plurality of p-type conductivity regions (first conductivity regions) 13 and n-type conductivity regions (second conductivity regions) are formed at the interface of the surface S1. The film thickness (hereinafter simply referred to as thickness) of the semiconductor substrate 11 in the stacking direction (Y-axis direction) is, for example, 10 μm or more and 700 μm or less.

[0023] The semiconductor substrate 11 may be, for example, a silicon substrate, but is not limited to this. The semiconductor substrate 11 may be made of, for example, germanium (Ge), gallium arsenide (GaAs), indium gallium arsenide (InGaAs), zinc selenide (ZnSe), gallium nitride (GaN), or indium gallium nitride (InGaN).

[0024] The p-type conductive region 13 contains p-type impurities, for example, 1e 18 cm -3 ~1e 21 cm -3 This is a region containing p-type impurities at a certain concentration (p-type impurity region), and multiple such regions are formed at the interface of the surface S1 of the semiconductor substrate 11. Specifically, the p-type conductive region 13 has three regions: a region constituting the anode 13A, a region constituting the drain 13B, and a region constituting the guard ring 13C. Each region is spaced apart from the others, and the drain 13B is formed in a ring shape around the anode 13A. The guard ring 13C is formed in a ring shape around the drain 13B. The thickness of the p-type conductive region 13 depends on the configuration of the unit pixels P, but for example, if the pitch of the unit pixels P is 10 μm or more and 100 μm or less, it is formed with a thickness of, for example, 3 μm or less from the interface of the surface S1 of the semiconductor substrate 11.

[0025] Anode 13A is to which a voltage is applied for reading out, for example, holes (h+) as signal charges from the carriers generated by photoelectric conversion, and is connected to electrode 16 (first electrode), for example. Anode 13A is individually formed, for example, approximately in the center of unit pixel P. The planar shape of anode 13A is not particularly limited and may be circular (see, for example, Figure 2) or polygonal. Anode 13A, for example, protrudes partly from the bottom surface of the embedded layer 14, which will be described later, towards the back surface S2. The size of anode 13A depends on the size of unit pixel P, but for example, when the pitch of unit pixel P is 10 μm or more and 100 μm or less, it is 0.1 μm or more and 10 μm or less.

[0026] Drain 13B is to which a voltage is applied to discharge dark current generated at the interface of surface S1 on the semiconductor substrate 11, for example, when irradiated with X-rays, and is connected to electrode 17 (second electrode), for example. Drain 13B is formed in a ring shape around anode 13A, so that dark current generated at the interface of surface S1 on the semiconductor substrate 11 when irradiated with X-rays is constantly discharged from drain 13B. This prevents dark current from flowing into anode 13A. The planar shape of drain 13B is not particularly limited and may be annular or polygonal (see, for example, Figure 2).

[0027] The guard ring 13C is for alleviating the electric field concentration to the drain 13B and simultaneously generating a horizontal electric field for assisting the transfer of signal charges (holes) in the horizontal direction (for example, in the XY plane direction). The guard ring 13C is formed in a ring shape around the drain 13B so as to surround the anode 13A and the drain 13B. Different from the anode 13A and the drain 13B, the guard ring 13C is in an electrically floating state. The guard ring 13C is formed in plural, for example, in a substantially concentric circular or substantially concentric polygonal shape centered on the anode 13A, at the interface of the surface S1 of the semiconductor substrate 11. Specifically, as shown in FIGS. 1 and 2, the guard ring 13C is composed of, for example, three p-type conductive regions and is formed triple (guard rings 13C1, 13C2, 13C3) around the drain 13B. Thus, by providing plural guard rings 13C, the electric field concentration can be dispersed at plural locations and simultaneously the horizontal electric field can be generated in a wide area. Also, on both sides of the guard rings 13C1, 13C2, 13C3, a p-type conductive region (the fifth first conductive region) with an impurity concentration lower than that of the p-type conductive region 13, for example, 1e 16 cm -3 ~1e 19 cm -3 or so may be further formed.

[0028] When the drain 13B and the guard ring are formed in a polygonal shape (for example, a rectangular shape), the corners are preferably formed in a curved shape as shown in FIG. 2. Thereby, the electric field concentration at the corners is alleviated. Also, in FIG. 2, the drain 13B and the guard ring are shown as an example provided continuously around the anode 13A, but it is not limited thereto. For example, a part thereof may be cut, or it may be formed intermittently.

[0029] The line width of the rings constituting the drain 13B and guard ring 13C is, for example, between 0.100 μm and 10 μm. The distance between the drain 13B and guard ring 13C is, for example, between 0.100 μm and 10 μm. Note that the line widths of the drain 13B and guard ring 13C do not necessarily have to be constant.

[0030] Furthermore, as shown in Figures 1 and 2, when multiple guard rings 13C are provided, it is preferable that the spacing between them be uniform throughout the entire formation area. This reduces the potential difference on the surface S1 of the semiconductor substrate 11 between the area where the wiring layer 23 is formed and the area where it is not formed, caused by X-ray irradiation (specifically, the electric field difference between the surface S1 of the semiconductor substrate 11 (n-type diffusion region) and the p-type conductivity region).

[0031] The n-type conductive layer 12 contains n-type impurities, for example, 1e 18 cm -3 ~1e 21 cm -3 This is a region containing a certain concentration of impurities (n-type impurity region) and is formed at the interface of the back surface S2 of the semiconductor substrate 11. The n-type conductive layer 12 is connected to, for example, a power supply VDD (see Figure 3), and when, for example, holes among the carriers generated by photoelectric conversion are read out as signal charges through the anode 13A, electrons (e-) are discharged through this n-type conductive layer 12. The thickness of the n-type conductive layer 12 depends on the configuration of the unit pixel P, but for example, when the pitch of the unit pixel P is 10 μm or more and 100 μm or less, it is formed, for example, with a thickness of 1 μm from the interface of the back surface S2 of the semiconductor substrate 11.

[0032] Figures 3 and 4 each illustrate an example of how to connect a power supply to the n-type conductive layer 12. Figure 3 shows an example in which a transparent electrode 18 is formed on the n-type conductive layer 12, and a power supply VDD is connected to it to apply a voltage from the back surface S2 side of the semiconductor substrate 11. Figure 4 shows an example in which a neutral region 11N is formed outside the depletion region 11D formed on the semiconductor substrate 11 in the peripheral region 110B around a pixel region 110A in which a plurality of unit pixels P are arranged, for example in a matrix, and a voltage is applied through this neutral region 11N via an n-type conductive region 19 provided at the interface of the surface S1 of the semiconductor substrate 11. In this case, as shown in Figure 4, it is preferable to form a plurality of high-voltage guard rings 13D between the unit pixels P formed in the pixel region 110A and the n-type conductive region 19 at the interface of the surface S1 of the semiconductor substrate 11 in the peripheral region 110B. Of the multiple high-voltage guard rings 13D, it is preferable that the high-voltage guard ring positioned closest to the pixel area 110A is connected to ground GND.

[0033] The embedding layer 14 is intended to prevent holes (signal charges) among the carriers generated in the semiconductor substrate 11 by photoelectric conversion from being transferred to the drain 13B or guard ring 13C. The embedding layer 14 is embedded inside the semiconductor substrate 11, specifically near the p-type conductive region 13, to contain n-type impurities at a higher concentration than the n-type semiconductor substrate 11, for example, 1e 14 cm - 3 ~1e 17 cm -3 This is an n-type conductive region containing a certain concentration. More specifically, the embedded layer 14 is provided in the region of the p-type conductive region 13 corresponding to the drain 13B and guard ring 13C, and has an opening in the region facing the anode 13A. As a result, the signal charge generated in the semiconductor substrate 11 is efficiently read out from the anode 13A. The embedded layer 14 is formed so as not to be in direct contact with the drain 13B and guard ring 13C. The thickness of the embedded layer 14 varies depending on the magnitude of the reverse bias applied voltage applied between the front surface S1 and back surface S2 of the semiconductor substrate 11, but is, for example, between 0.100 μm and 10 μm.

[0034] The insulating layer 15 is formed on the surface S1 of the semiconductor substrate 11. The insulating layer 15 is formed using an inorganic insulating material. Examples of inorganic insulating materials include silicon oxide (SiO2), silicon nitride (SiN), aluminum oxide (Al2O3), and hafnium oxide (HfO2). The insulating layer 15 is formed by including at least one of these materials.

[0035] The n-type conductivity region 21 is a region containing n-type impurities and, as described above, is located at the interface of the surface S1 of the semiconductor substrate 11 between the anode 13A and the drain 13B. The impurity concentration of the n-type conductivity region 21 is, for example, 1e 16 cm -3 ~1e 19 cm -3 The density is approximately as follows. The thickness of the n-type conductive region 21 depends on the configuration of the unit pixels P, but for example, when the pitch of the unit pixels P is 10 μm or more and 100 μm or less, it is formed with a thickness of, for example, 0.1 μm or more and 3 μm or less from the interface of the surface S1 of the semiconductor substrate 11.

[0036] LDA22 is a region containing p-type impurities (p-type impurity region), and is located at the interface of the surface S1 of the semiconductor substrate 11 between the anode 13A and the n-type conductivity region 21, and between the drain 13B and the n-type conductivity region 21, as shown in Figures 1 and 2. The impurity concentration of LDA22 is lower than the impurity concentration of the anode 13A, drain 13B, and the p-type conductivity region 13 that forms the guard ring 13C, and is such that it is depleted by fixed charges (holes) generated at the interface of the insulating layer 15 with the surface S1 of the semiconductor substrate 11 by X-ray irradiation. Specifically, although it depends on the amount of X-ray irradiation, for example, the peak concentration is 1e 17 cm -3 ~1e 19 cm -3The concentration is low. The thickness of LDA22 depends on the configuration of the unit pixel P, but for example, when the pitch of the unit pixel P is 10 μm or more and 100 μm or less, it is formed with a thickness of, for example, 0.1 μm or more and 3 μm or less from the interface of the surface S1 of the semiconductor substrate 11.

[0037] Although not shown in the diagram, the substrate is placed on the insulating layer 15, with, for example, the electrodes 16 and 17 and logic circuits formed on it.

[0038] Figures 5A and 5B schematically represent the interface of the surface S1 of the semiconductor substrate 11 before (Figure 5A) and after (Figure 5B) X-ray irradiation when only an n-type conductive region 21 is provided around the anode 13A. As described above, when X-rays are irradiated, fixed charges (holes) are generated at the interface of the insulating layer 15 with the surface S1 of the semiconductor substrate 11. The interface of the surface S1 of the semiconductor substrate 11 becomes n-type due to these positive fixed charges. As a result, the depletion layer width W decreases and the pn junction becomes steeper. At that time, partly because the area of ​​the pn junction is large, the capacitance increases, for example, by more than 1.5 times.

[0039] Figures 6A and 6B schematically show the interface of the surface S1 of the semiconductor substrate 11 before (Figure 6A) and after (Figure 6B) X-ray irradiation when an LDA 22 is provided between the anode 13A and the n-type conductive region 21. When an LDA 22 is provided between the anode 13A and the n-type conductive region 21 as in this embodiment, the area of ​​the pn junction decreases, and the LDA 22 is depleted by the conversion to n-type due to X-ray irradiation, thus reducing the decrease in the depletion layer width W. Therefore, the capacitance fluctuation (increase) before and after X-ray irradiation is suppressed.

[0040] (1-2. Method for manufacturing photodetectors) The light-receiving element 1 can be manufactured, for example, as follows. First, an n-type conductive layer 12 is formed on the back surface S2 of the semiconductor substrate 11 using ion implantation technology. Next, a mask is formed in a predetermined area on the surface S1 of the semiconductor substrate 11, and then an n-type conductive layer (embedded layer 14) is formed by doping with an n-type impurity (e.g., phosphorus (P)) using ion implantation technology. Next, a mask is formed in a predetermined area on the surface S1 of the semiconductor substrate 11, and then a p-type conductive region 13 (anode 13A, drain 13B, and guard ring 13C) is formed by doping with a p-type impurity (e.g., boron (B)) using ion implantation technology. Subsequently, similarly, a mask is formed in a predetermined area on the surface S1 of the semiconductor substrate 11, and then an n-type conductive region 21 and LDA 22 are sequentially formed by doping with an n-type impurity (e.g., phosphorus (P)) or a p-type impurity (e.g., boron (B)) using ion implantation technology. Next, an insulating layer 15 is formed on the surface S1 of the semiconductor substrate 11, for example, using a CVD (Chemical Vapor Deposition) method. This completes the photodetector 1 shown in Figure 1. do.

[0041] (1-3. Action / Effect) In the photodetector 1 of this embodiment, an n-type conductive region 21 is provided between the anode 13A and the drain 13B at the interface of the surface S1 of the semiconductor substrate 11, and an LDA 22 is provided between the anode 13A and the n-type conductive region 21. This prevents an increase in capacitance due to the conversion of the interface of the surface S1 of the semiconductor substrate 11 to n-type after X-ray irradiation. This will be explained below.

[0042] As mentioned above, solid-state imaging devices are used in a variety of applications, such as imaging devices in digital still cameras and video cameras, electronic devices such as mobile terminals with imaging capabilities, and electromagnetic wave sensors that detect various wavelengths other than visible light. CMOS image sensors, which read out the signal charge accumulated in a photodiode (a photoelectric conversion element) via a MOS transistor, are widely used in these solid-state imaging devices.

[0043] A unit pixel of a CMOS image sensor comprises, for example, a photodiode (PD) with a HAD (Hole Accumulated Diode) structure within a semiconductor substrate, and a floating diffusion region (FD) positioned on either side of the transfer gate relative to the photodiode. In addition to these, the unit pixel also includes, for example, a reset transistor, a select transistor, and an amplifier transistor.

[0044] Another configuration of the unit pixel in a CMOS image sensor is one in which the photoelectric conversion region and FD are integrated within the semiconductor substrate, without a HAD. This structure is simple and easy to manufacture, and allows for the application of any potential difference to the pn junction forming the photoelectric conversion region. Therefore, it is easy to increase the thickness of the photoelectric conversion region, and this advantage has led to its widespread use in sensors for scientific applications requiring high-sensitivity measurement.

[0045] Incidentally, radiation imaging sensors and electromagnetic wave detection devices require the reduction of the effects of the total dose effect caused by X-ray irradiation. The total dose effect is a phenomenon in which material degradation occurs due to the accumulation of the total amount of incident radiation. When a large amount of radiation such as X-rays is incident on a semiconductor device, electron-hole pairs are generated in the oxide film due to ionization. Although it depends on the electric field in the oxide film, for example, in the electron-hole pair, the hole becomes a fixed charge, and the electron breaks the Si-H bond at the interface S1 of the semiconductor substrate 11, increasing the interface energy levels. As a result, various properties of the semiconductor device deteriorate.

[0046] In contrast, in this embodiment, an n-type conductivity region 21 is provided on the surface S1 of the semiconductor substrate 11 between the anode 13A and the drain 13B, and an LDA 22 consisting of a p-type conductivity region is provided between the anode 13A and the n-type conductivity region 21. This reduces the effect of the interface of the semiconductor substrate 11 becoming n-type due to the generation of fixed charges (holes) at the interface of the insulating layer 15 with the surface S1 of the semiconductor substrate 11 by X-ray irradiation.

[0047] As described above, the photodetector 1 of this embodiment makes it possible to reduce the effect of the total dose effect caused by X-ray irradiation.

[0048] Furthermore, in the photodetector 1 of this embodiment, the LDA 22 is set to an impurity concentration such that it is depleted by the n-type conversion of the interface S1 of the semiconductor substrate 11 due to X-ray irradiation. Compared to the case where LDA 22 is not provided (see, for example, Figure 5B), the area of ​​the pn junction with the n-type conductive region 21 is reduced, and the reduction in the depletion layer width is also reduced. Therefore, the capacitance fluctuation (increase) before and after X-ray irradiation is suppressed, and the decrease in conversion efficiency is suppressed.

[0049] Next, Modifications 1 to 17 of the present disclosure and examples of their application will be described. In the following, components similar to those in the above embodiments will be denoted by the same reference numerals, and their descriptions will be omitted as appropriate.

[0050] <2. Variant> (2-1. Variation 1) Figure 7 schematically shows an example of a cross-sectional configuration of a light-receiving element (light-receiving element 1A) according to Modification 1 of the present disclosure. Similar to the above embodiment, the light-receiving element 1A consists of, for example, a PIN-type photodiode that applies a reverse bias between the front and back surfaces of a semiconductor substrate 11, and constitutes one pixel (unit pixel P) in a radiation image sensor (e.g., X-ray image sensor 100) or electromagnetic wave detection device that reads information about a subject (images of a subject) based on radiation (e.g., alpha rays, beta rays, gamma rays, and X-rays, etc.).

[0051] For example, as shown in Figure 24, when a wiring layer 23 that is electrically connected to the drain 13B and spans multiple guard rings 13C is provided within the insulating layer 15, it is preferable that the insulating layer 15 between the surface S1 of the semiconductor substrate 11 and the wiring layer 23 be a single layer film made of silicon oxide. Alternatively, when silicon nitride is used as the constituent material of the insulating layer 15, it is preferable that the silicon nitride film be formed at a position 30 nm or more away from the surface S1 of the semiconductor substrate 11. In other words, when the insulating layer 15 is a laminated film of a silicon oxide film and a silicon nitride film, it is preferable to laminate the silicon oxide film having a thickness of 30 nm or more from the surface S1 of the semiconductor substrate 11 and the silicon nitride film in this order.

[0052] In typical CMOS technology, the CS interlayer film is a film that can achieve a selectivity ratio between silicon oxide and dry etching, such as a silicon nitride film, and is placed near the silicon substrate to act as an etching stopper film during CS etching. However, since silicon nitride films contain more fixed charges than silicon oxide films, placing a silicon nitride film near the surface of a silicon substrate with a low concentration of impurities may affect the carrier concentration in the silicon substrate. Furthermore, the raw material gas used to deposit the silicon nitride film can nitride the surface of the silicon substrate, leading to an increase in interface states and a problem of increased dark current.

[0053] In contrast, in this modified example, the insulating layer 15 between the surface S1 of the semiconductor substrate 11 and the wiring layer 23 formed above it is made of a single layer of silicon oxide or a laminated film in which a silicon oxide film having a thickness of 30 nm or more from the surface S1 of the semiconductor substrate 11 and a silicon nitride film are stacked in that order. This reduces the generation of interface states on the surface S1 of the semiconductor substrate 11 during X-ray irradiation. Therefore, in addition to the effects of the above embodiment, it becomes possible to reduce the generated recombination current and reduce the generation of dark current.

[0054] Furthermore, when a silicon nitride film is placed near the semiconductor substrate 11, the total dose effect of X-rays causes, for example, the charge of one of the electron-hole pairs ionized in the insulating layer 15 to accumulate in the silicon nitride film, depending on the electric field in the insulating layer 15, thereby making the surface of the semiconductor substrate 11 n-type. However, in this modified example, this effect can be further reduced.

[0055] Furthermore, in direct conversion type photodetectors 1(1A) that deplete a silicon substrate (semiconductor substrate 11) as in the above embodiment and this modified example, the impurity concentration in the semiconductor substrate 11 is very low. Therefore, if variations occur in the amount of fixed charge contained in the silicon nitride film due to variations in the manufacturing process, the conductivity of the surface S1 of the semiconductor substrate 11 is likely to fluctuate due to these variations. Fluctuations in the conductivity of the surface S1 of the semiconductor substrate 11 cause variations in pixel characteristics. In contrast, in this modified example, a silicon oxide film is provided at least near the surface S1 of the semiconductor substrate 11, thereby reducing variations in the conductivity of the surface S1 of the semiconductor substrate 11. Therefore, in addition to the effects of the above embodiment, it is possible to reduce variations in pixel characteristics.

[0056] In this modified example, the wiring structure formed on the surface S1 of the semiconductor substrate 11 of the photodetector 1A can be formed, for example, as follows. First, an insulating layer 15 made of silicon oxide is deposited on the surface S1 of the semiconductor substrate 11, for example, using the CVD method. Next, a resist is patterned on the insulating layer 15 using the photolithography method, and then openings reaching the anode 13A and drain 13B are formed by dry etching. At this time, etching conditions are used that allow for an etching rate difference between silicon oxide (insulating layer 15) and silicon (semiconductor substrate 11) so that etching stops at the surface of the semiconductor substrate 11. Next, the resist is removed, and a tungsten film is deposited on the insulating layer 15 and in the openings, for example, using the CVD method. After that, the tungsten film on the insulating layer 15 is removed using the dry etching or CMP (Chemical Mechanical Polishing) method, and then the wiring layer 23 is formed as appropriate. This forms the light-receiving element 1A shown in Figure 7.

[0057] (2-2. Variation 2) Figure 8 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1B) according to Modification 2 of the present disclosure. Similar to the above embodiment, the photodetector 1B consists of a PIN-type photodiode that applies a reverse bias between the front and back surfaces of a semiconductor substrate 11, and constitutes one pixel (unit pixel P) in a radiation image sensor (e.g., X-ray image sensor 100) or electromagnetic wave detection device that reads information about an object based on radiation (e.g., alpha rays, beta rays, gamma rays, and X-rays, etc.) (images of an object). In this modified example, the photodetector 1B has a gate electrode 24 provided in an insulating layer 15 between the anode 13A and the drain 13B, and the insulating layer (gate insulating layer 25) between the semiconductor substrate 11 and the gate electrode 24 is formed using a high dielectric material.

[0058] As described above, the gate electrode 24 is for applying an electric field to the interface S1 of the semiconductor substrate 11 between the anode 13A and the drain 13B. Specifically, it applies an electric field in a direction that moves holes generated near the interface S1 of the semiconductor substrate 11 away from the interface of the semiconductor substrate 11. More specifically, a negative voltage (-) is applied to the gate electrode 24 with respect to the potential of the semiconductor substrate 11, thereby applying an electric field of, for example, 0.5 MV / cm or more to the interface S1 of the semiconductor substrate 11. The gate electrode 24 is also for reducing the volume of the insulating layer 15 provided on the semiconductor substrate 11 between the anode 13A and the drain 13B. This reduces the increase in positive fixed charge generated near the interface of the insulating layer 15 with the surface S1 of the semiconductor substrate 11 and the increase in the interface state of the surface S1 of the semiconductor substrate 11 due to X-ray irradiation.

[0059] The gate electrode 24 is provided between the anode 13A and the drain 13B via a gate insulating film 15A, for example, so as to surround the anode 13A in a plan view. The gate electrode 24 can be formed using, for example, polysilicon (poly-Si). The polysilicon constituting this gate electrode 24 may be an intrinsic semiconductor free of impurities, or it may be an impurity semiconductor containing n-type or p-type impurities. In addition, the polysilicon constituting the gate electrode 24 may have, for example, multiple semiconductor regions with different impurity concentrations.

[0060] The gate insulating layer 25 is formed on the surface S1 of the semiconductor substrate 11 using a high-dielectric material (High-k) having a higher dielectric constant than the silicon oxide constituting the insulating layer 15. The high-dielectric material constituting the gate insulating layer 25 is preferably a material that forms a junction surface with a smaller band offset than the junction interface between the semiconductor substrate 11 and the insulating layer 15, and has fewer interface states with the semiconductor substrate 11. Specifically, examples include tantalum oxide (Ta2O5), hafnium oxide, aluminum oxide, and yttrium oxide (Y2O3).

[0061] Thus, in this modified example, a gate electrode 24 is provided on the surface S1 of the semiconductor substrate 11 via a gate insulating layer 25 between the anode 13A and the drain 13B, which are located at the interface of the surface S1 of the semiconductor substrate 11. This reduces the increase in positive fixed charge generated at the interface of the surface S1 of the semiconductor substrate 11 when irradiated with X-rays, thereby reducing fluctuations in the capacitance of the anode 13A and the electric field at the interface of the surface S1 of the semiconductor substrate 11. In addition, the generation of interface states at the surface S1 of the semiconductor substrate 11 is suppressed. Therefore, it is possible to reduce the generation of dark current.

[0062] Furthermore, in this modified example, since the gate insulating layer 25 is formed using a high dielectric material, the band gap from the insulating layer 15 to the semiconductor substrate 11 is gradually narrowed, thereby reducing the interface state density between the insulating layer 15 and the semiconductor substrate 11. As a result, it becomes possible to further reduce the generation of dark current.

[0063] (2-3. Variation 3) Figure 9 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1C) according to Modification 3 of this disclosure. Figure 10 shows an enlarged view of the cross-sectional configuration of the main part of the photodetector 1C shown in Figure 9. Similar to the above embodiment, the photodetector 1C consists of, for example, a PIN-type photodiode that applies a reverse bias between the front and back surfaces of a semiconductor substrate 11, and constitutes one pixel (unit pixel P) in a radiation image sensor (e.g., X-ray image sensor 100) or electromagnetic wave detection device that reads information about a subject based on radiation (e.g., alpha rays, beta rays, gamma rays, and X-rays, etc.) (images of a subject).

[0064] In Modification 2, an example was shown in which the gate electrode 24 is selectively provided on the semiconductor substrate 11 between the anode 13A and the drain 13B. However, the gate electrode 24 may also be formed on the drain 13B, between the drain 13B and the guard ring 13C1, and on the guard ring 13C1, as shown in Figure 11. This creates a narrow gap between the gate electrode 24 at the drain 13B end and the guard ring 13C1 end, where high electric fields are generated. Furthermore, in this case, the gate insulating layer 25 may be patterned for each gate electrode 24, and an air gap G may be provided between the laminated film of each gate insulating layer 25 and the gate electrode 24.

[0065] The gate electrode 24 can be fabricated, for example, using lithography and reactive ion etching (RIE). The gate insulating layer 25 can be fabricated, for example, using wet etching. The gap G between the laminated films of each gate insulating layer 25 and the gate electrode 24 can be formed, for example, by depositing the insulating layer 15 using lithography and CVD, setting appropriate coverage conditions.

[0066] Furthermore, the gate electrodes 24 provided on the drain 13B, between the drain 13B and the guard ring 13C1, and on the guard ring 13C1 may be provided intermittently, for example, as shown in Figure 12.

[0067] As described above, in this modified example, gate electrodes 24 are formed on the drain 13B, between the drain 13B and the guard ring 13C1, and on the guard ring 13C1, respectively. The gate insulating layer 25 is patterned for each gate electrode 24, and a gap G is provided between each gate insulating layer 25 and the laminated film of the gate electrode 24. This reduces the increase in positive fixed charge generated at the interface of the surface S1 of the semiconductor substrate 11 when irradiated with X-rays, thereby reducing the capacitance of the anode 13A and the fluctuation of the electric field at the interface of the surface S1 of the semiconductor substrate 11. In addition, the generation of interface states at the surface S1 of the semiconductor substrate 11 is suppressed. Therefore, it is possible to reduce the generation of dark current.

[0068] (2-4. Modification 4) Figure 13 schematically shows an example of a cross-sectional configuration of a photodetector (photodetector 1D) according to Modification 4 of the present disclosure. Similar to the above embodiment, the photodetector 1D consists of, for example, a PIN-type photodiode that applies a reverse bias between the front and back surfaces of the semiconductor substrate 11, and constitutes one pixel (unit pixel P) in a radiation image sensor (e.g., X-ray image sensor 100) or electromagnetic wave detection device that reads information about a subject (images of a subject) based on radiation (e.g., alpha rays, beta rays, gamma rays, and X-rays, etc.). In this modified example, the photodetector 1D has a void G closed by an insulating layer 15 formed on the surface S1 of the semiconductor substrate 11 so as to cover the pn junction region around the anode 13A.

[0069] Specifically, the air gap G is formed around the via V that electrically connects the anode 13A and the electrode 16, and more specifically, on the semiconductor substrate 11 between the anode 13A, which is a strong electric field generation region, and the n-type conductive region 21 provided around it.

[0070] Alternatively, as shown in Figure 14, for example, a groove 11X may be formed by carving into the surface S1 of the semiconductor substrate 11, an anode 13A may be formed at the bottom of the groove 11X, and a void G may be formed within the groove 11X. This makes it easier to form the void G than forming it on the flat surface S1 of the semiconductor substrate 11 as shown in Figure 13.

[0071] Thus, in this modified example, a gap G closed by the insulating layer 15 is provided so as to cover the pn junction region around the anode 13A. As a result, the generation of fixed charges at the interface between the anode 13A and the surface S1 of the semiconductor substrate 11 surrounding it is eliminated, thereby preventing the interface of the semiconductor substrate 11 surface S1 surrounding the anode 13A from becoming n-type due to X-ray irradiation, and reducing the decrease in the depletion layer width. Therefore, capacitance fluctuations are eliminated, and a decrease in conversion efficiency can be prevented. In addition, the capacitance of the anode 13A is reduced, enabling high-speed operation.

[0072] (2-5. Modification 5) Figure 15 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1E) according to Modification 5 of the present disclosure. Similar to the above embodiment, the photodetector 1E consists of, for example, a PIN-type photodiode that applies a reverse bias between the front and back surfaces of a semiconductor substrate 11, and constitutes one pixel (unit pixel P) in a radiation image sensor (e.g., X-ray image sensor 100) or electromagnetic wave detection device that reads information about a subject (images of a subject) based on radiation (e.g., alpha rays, beta rays, gamma rays, and X-rays, etc.). In this modification, the photodetector 1E is provided with an electrically floating field plate 26 above the guard ring 13C.

[0073] The field plate 26 is provided above the guard ring 13C, for example, above the corners of the guard ring 13C3, which is located on the outermost periphery, as shown in Figure 16A, and is wider than the guard ring 13C3 so as to cover it. The field plate 26 can be formed using a conductive metal material or polysilicon. The field plate 26 is electrically connected to the guard ring 13C3, for example, via via V, and is electrically floating as described above. The field plate 26 and the guard ring 13C3 form, for example, an ohmic joint.

[0074] When irradiated with X-rays, a high electric field is generated not only around the anode 13A, but also at the interface of the semiconductor substrate 11 between guard rings 13C1, 13C2, and 13C3, resulting in a steep potential. In particular, at the corners of the outermost guard ring 13C3, if the distance to adjacent unit pixels is large, a stronger electric field is generated than in the straight sections, making breakdown voltage degradation more likely.

[0075] In contrast, in this modified example, a field plate 26 covering the guard ring 13C3 is provided above the guard ring 13C, particularly above the corners of the guard ring 13C3 located on the outermost periphery where strong electric fields are likely to be generated. This makes it possible to mitigate the concentration of electric fields at the corners and reduce the rise in potential caused by X-ray irradiation.

[0076] Furthermore, the field plate 26 may be formed continuously to cover not only the corners of the guard ring 13C3, but the entire guard ring 13C3. In addition, as shown in Figure 16B, it may be formed not only on the guard ring 13C3, but on each of the guard rings 13C1, 13C2, and 13C3 that constitute the guard ring 13C. In that case, due to layout constraints, it would be difficult to extend it on both sides of the guard rings 13C1, 13C2, and 13C3, so as shown in Figure 17, it may be extended only on one side of the guard rings 13C1, 13C2, and 13C3 (for example, the inside of the unit pixel P (anode 13A side)). This makes it possible to reduce the rise in potential due to X-ray irradiation of the entire guard rings 13C1, 13C2, and 13C3.

[0077] (2-6. Variation 6) Figure 18 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1F) according to Modification 6 of the present disclosure. Similar to the above embodiment, the photodetector 1F consists of a PIN-type photodiode that applies a reverse bias between the front and back surfaces of the semiconductor substrate 11, and constitutes one pixel (unit pixel P) in a radiation image sensor (e.g., X-ray image sensor 100) or electromagnetic wave detection device that reads information about a subject based on radiation (e.g., alpha rays, beta rays, gamma rays, and X-rays, etc.) (images of a subject). In this modification, the photodetector 1F is further provided with an n-type conductive region 27 near the interface of the surface S1 of the semiconductor substrate 11 between the drain 13B and the guard ring 13C1 and between adjacent guard rings 13C1, 13C2, and 13C3.

[0078] The n-type conductivity region 27 is a region containing n-type impurities and corresponds to a specific example of the "second second conductivity region" of this disclosure. As described above, the n-type conductivity region 27 is provided near the interface of the surface S1 of the semiconductor substrate 11 between the drain 13B and the guard ring 13C1 and between adjacent guard rings 13C1, 13C2, and 13C3. The impurity concentration of the n-type conductivity region 27 is higher than the impurity concentration of the n-type conductivity region constituting the embedded layer 14, for example, 1e 16 cm-3 ~1e 19 cm -3 The density is of a certain degree. The thickness of the n-type conductive region 27 depends on the configuration of the unit pixel P, but for example, when the pitch of the unit pixel P is 10 μm or more and 100 μm or less, it is formed with a thickness of, for example, 0.1 μm or more and 3 μm or less from the interface of the surface S1 of the semiconductor substrate 11.

[0079] As described above, in this modified example, an n-type conductive region 27 is provided near the interface of the surface S1 of the semiconductor substrate 11 between the drain 13B and the guard ring 13C1, and between adjacent guard rings 13C1, 13C2, and 13C3. This reduces the change in the current path between the drain 13B and the guard ring 13C1, and between adjacent guard rings 13C1, 13C2, and 13C3 before and after X-ray irradiation. Therefore, the rise in potential of each guard ring 13C1, 13C2, and 13C3 after X-ray irradiation is reduced, making it possible to suppress the increase in leakage current due to electric field concentration and the poor charge transfer due to the weakening of the horizontal transfer electric field.

[0080] Furthermore, the n-type conductive region 27 provided near the interface of the surface S1 of the semiconductor substrate 11 between the drain 13B and the guard ring 13C1 and between each adjacent guard ring 13C1, 13C2, 13C3 may be provided in contact with the guard ring 13C1, 13C2, 13C3 on the side opposite to the anode 13A, as shown in Figure 19, for example. This increases the distance between the n-type conductive region 27 and the guard rings 13C1, 13C2, 13C3, thereby mitigating the electric field and reducing the generation of leakage current. Moreover, on the side of the drain 13B on the side of the guard ring 13C1 and the side of the guard rings 13C1, 13C2, 13C3 opposite to the side to which the n-type conductive region 27 is in contact, a concentration lower than the impurity concentration of the p-type semiconductor region forming the guard rings 13C1, 13C2, 13C3, for example, 1e, may be provided, as shown in Figure 20, for example. 16 cm -3 ~1e 19 cm -3A p-type conductive region 28 corresponding to a specific example of the "sixth first conductive type region" of the present disclosure having an impurity concentration of a certain degree may be provided. Thereby, the electric field on the surface S1 of the semiconductor substrate 11 between the drain 13B and the guard ring 13C1 and between adjacent guard rings 13C1, 13C2, 13C3 is relaxed, and it becomes possible to further reduce the increase in the electric field when the potential of the surface S1 of the semiconductor substrate 11 rises due to X-ray irradiation. Furthermore, the widths (W1, W2, W3) of the n-type conductive regions 27 provided between the drain 13B and the guard ring 13C1 and between adjacent guard rings 13C1, 13C2, 13C3 respectively do not necessarily have to be uniform. For example, as shown in FIG. 21, the n-type conductive region 27 may be gradually enlarged (W1 < W2 < W3) toward the outside of the unit pixel P. Thereby, the potential of the outer guard ring 13C rises more, and the effect of promoting the transfer of signal charges in the lateral direction can be obtained. Also, the impurity concentrations of the n-type conductive regions 27 provided between the drain 13B and the guard ring 13C1 and between adjacent guard rings 13C1, 13C2, 13C3 respectively do not necessarily have to be uniform. For example, as shown in FIG. 22, the n-type conductive region 27 may be gradually enlarged toward the outside of the unit pixel P. Thereby, similarly to the above, the potential of the outer guard ring 13C rises more, and the effect of promoting the transfer of signal charges in the lateral direction can be obtained.

[0081] (2-7. Modified Example 7) Figure 23 schematically shows an example of a cross-sectional configuration of a light-receiving element (light-receiving element 1G) according to Modification 7 of the present disclosure. Similar to the above embodiment, the light-receiving element 1G consists of, for example, a PIN-type photodiode that applies a reverse bias between the front and back surfaces of a semiconductor substrate 11, and constitutes one pixel (unit pixel P) in a radiation image sensor (e.g., X-ray image sensor 100) or electromagnetic wave detection device that reads information about a subject (images a subject) based on radiation (e.g., alpha rays, beta rays, gamma rays, and X-rays, etc.). In this modification, the light-receiving element 1G is provided above the unit pixel P, for example, as shown in Figure 24, by being provided in the wiring layers M2 and later of the wiring layers M1, M2, M3 that are formed in multiple layers within the insulating layer 15 provided on the surface S1 of the semiconductor substrate 11.

[0082] As mentioned above, when X-rays are irradiated, the potential of the surface S1 of the semiconductor substrate 11 rises, for example, as shown in the orthogonal w / oM1 in Figure 25. On the other hand, if wiring (for example, wiring for low voltage application such as drain 13B or GND terminal) is formed above the surface S1 of the semiconductor substrate 11, spanning guard rings 13C1, 13C2, and 13C3, the potential of the surface S1 of the semiconductor substrate 11 between the guard rings 13C1, 13C2, and 13C3 below the wiring is suppressed, for example, as shown in the orthogonal w / oM1 in Figure 25.

[0083] In contrast, in this modified example, the wiring that spans the drain 13B and the multiple guard rings 13C is provided in the wiring layer M2 and later of the multiple wiring layers M1, M2, M3 formed in multiple layers within the insulating layer 15, for example, at least 500 nm away from the surface S1 of the semiconductor substrate 11. This suppresses the modulation of the potential of the surface S1 of the semiconductor substrate 11 between the guard rings 13C1, 13C2, and 13C3, where the wiring is formed above, due to X-ray irradiation. As a result, the electric field difference of the surface S1 of the semiconductor substrate 11 after X-ray irradiation with or without wiring is reduced, making it possible to suppress the degradation of the breakdown voltage.

[0084] (2-8. Variation 8) Figure 26 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1H) according to Modification 8 of this disclosure. Figure 27 schematically shows the planar configuration of the photodetector 1H shown in Figure 26, and Figure 26 shows the cross-section along line II shown in Figure 27. The photodetector 1H, similar to the above embodiment, consists of, for example, a PIN-type photodiode that applies a reverse bias between the front and back surfaces of a semiconductor substrate 11, and constitutes one pixel (unit pixel P) in a radiation image sensor (e.g., X-ray image sensor 100) or electromagnetic wave detection device that reads information about a subject based on radiation (e.g., alpha rays, beta rays, gamma rays, and X-rays, etc.) (images of a subject). In this modification, the photodetector 1H has an n-type conductive region 29 near the interface of the surface S1 of the semiconductor substrate 11 between adjacent unit pixels P.

[0085] The n-type conductivity region 29 is a region containing n-type impurities and corresponds to a specific example of the "fourth second conductivity region" of this disclosure. The n-type conductivity region 29 is intended to raise the potential at the boundary between adjacent unit pixels P higher than the potential inside the unit pixels P, and is provided near the interface of the surface S1 of the semiconductor substrate 11 so as to surround the unit pixels P. In other words, the n-type conductivity region 29 is provided in a grid pattern, for example, as shown in Figure 27, in a pixel region 110A where unit pixels P are arranged in a matrix. The impurity concentration of the n-type conductivity region 29 is higher than the impurity concentration of the n-type conductivity region constituting the embedded layer 14, for example, 1e 16 cm -3 ~1e 19 cm -3 The concentration is high. The thickness of the n-type conductive region 29 depends on the configuration of the unit pixel P, but it is shallower than the embedded layer 14. For example, when the pitch of the unit pixel P is 10 μm or more and 100 μm or less, it is formed with a thickness of, for example, 0.1 μm or more and 3 μm or less from the interface of the surface S1 of the semiconductor substrate 11.

[0086] As described above, the guard ring 13C is intended to alleviate the concentration of the electric field on the drain 13B and simultaneously generate a horizontal electric field to assist in the horizontal transfer of signal charges. However, at the boundaries of adjacent unit pixels P, it is difficult to form a sufficient potential gradient for high-speed transfer of signal charges. Furthermore, if the X-ray irradiation differs significantly between adjacent unit pixels P, the potential of the guard ring 13C may differ between adjacent unit pixels P. In such cases, for example, the potential of the outermost guard ring 13C (e.g., guard ring 13C3) of a unit pixel P2 adjacent to a unit pixel P1 with an increased potential will differ from the potential of the guard ring 13C of the unit pixel P1 with an increased potential, resulting in a potential difference between the guard rings 13C3 of adjacent unit pixels P1 and P2. This increases the rate at which charge is transferred to unit pixel P1, and the charge generated between adjacent unit pixels P1 and P2 is not properly transferred.

[0087] In contrast, in this modified version, an n-type conductive region 29 is provided near the interface S1 of the surface of the semiconductor substrate 11 between adjacent unit pixels P. This makes the potential at the boundary between adjacent unit pixels P higher than the potential inside the unit pixels P. This prevents the inflow of signal charge into adjacent unit pixels P and enables high-speed transfer of signal charge. Furthermore, the reduced signal charge transfer time makes it possible to increase the frame rate.

[0088] Furthermore, in this modified example, an example is shown in which an n-type impurity region (n-type conductive region 29) is provided between adjacent unit pixels P. However, as shown in Figure 28, for example, a p-type impurity region (p-type conductive region 13X) may be provided at the boundary between adjacent unit pixels P, and the outermost guard rings 13C (for example, guard ring 13C3) of each may be connected.

[0089] The p-type conductive region 13X is a region containing p-type impurities and corresponds to a specific example of the "seventh first conductive region" of this disclosure. The p-type conductive region 13X has an impurity concentration equivalent to that of the p-type conductive region 13 which forms, for example, a guard ring 13C. The thickness of the p-type conductive region 13X is equivalent to that of the guard ring 13C.

[0090] In this way, by providing a p-type conductive region 13X at the boundary between adjacent unit pixels P and connecting the outermost guard rings 13C1 of each, it becomes possible to equalize the potential between adjacent unit pixels P. Therefore, the potential drop between adjacent unit pixels P is eliminated, and charge loss can be suppressed. Furthermore, by aligning the charge dispersion characteristics between adjacent unit pixels P, it becomes possible to reduce the system and software processing required to correct the charge dispersion characteristics in, for example, the X-ray image sensor 100.

[0091] In Figure 28, an example is shown in which the outermost guard rings 13C3 of adjacent unit pixels P are connected at one point in each direction. However, as shown in Figure 29, for example, they may be connected at two points in each direction. Alternatively, as shown in Figure 30, for example, the outermost guard rings 13C3 may be formed over the entire interface of the surface S1 of the semiconductor substrate 11 as a common region with adjacent unit pixels P.

[0092] (2-9. Variation 9) Figure 31 schematically shows an example of a planar configuration of a photodetector (photodetector 1I) according to Modification 9 of the present disclosure. Similar to the above embodiment, the photodetector 1I consists of, for example, a PIN-type photodiode that applies a reverse bias between the front and back surfaces of a semiconductor substrate 11, and constitutes a single pixel (unit pixel P) in a radiation image sensor (e.g., X-ray image sensor 100) or electromagnetic wave detection device that reads information about a subject (images of a subject) based on radiation (e.g., alpha rays, beta rays, gamma rays, and X-rays, etc.). In this modified example, the photodetector 1I has multiple guard rings 13C1, 13C2, and 13C3 provided on adjacent unit pixels P, which are electrically connected to each other via wirings 31A, 31B, and 31C formed in, for example, an insulating layer 15.

[0093] Thus, in this modified example, the guard rings 13C1, 13C2, and 13C3 provided on adjacent unit pixels P are electrically connected to each other. Therefore, even if X-rays are irradiated locally and the potential of the guard ring 13C of some unit pixels P rises, this potential rise is averaged out across the multiple unit pixels P arranged in the pixel region 110A, thereby reducing the degradation of the breakdown voltage.

[0094] Furthermore, guard rings 13C1, 13C2, and 13C3, which are connected to each other by wiring 31A, 31B, and 31C, may also be connected to power supplies 32A, 32B, and 32C, respectively. This prevents the potential of each guard ring 13C1, 13C2, and 13C3 from rising due to X-ray irradiation, and further reduces the degradation of their withstand voltage.

[0095] When applying voltage to each guard ring 13C1, 13C2, and 13C3, the voltage is set considering the trade-off relationship between power consumption and pixel characteristics. For example, voltages such as 10V, 20V, 30V or 20V, 40V, 60V are applied to each guard ring 13C1, 13C2, and 13C3 so that the voltage increases from the inner circumference to the outer circumference of the unit pixel P. This creates a desired step potential on the surface S1 of the semiconductor substrate 11, enabling high-speed transfer of signal charge.

[0096] (2-10. Variation 10) Figure 32 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1J) according to Modification 10 of the present disclosure. Similar to the above embodiment, the photodetector 1J consists of, for example, a PIN-type photodiode that applies a reverse bias between the front and back surfaces of a semiconductor substrate 11, and constitutes one pixel (unit pixel P) in a radiation image sensor (e.g., X-ray image sensor 100) or electromagnetic wave detection device that reads information about a subject (images of a subject) based on radiation (e.g., alpha rays, beta rays, gamma rays, and X-rays, etc.).

[0097] In this modified example, the photodetector 1J has an anode 13Ax extending in the in-plane direction (XZ plane direction) of the semiconductor substrate 11 between the drain 13B and the embedding layer 14. The anode 13Ax may be provided on the back surface S2 side of the semiconductor substrate 11, as shown in Figure 33. The impurity concentration of this anode 13Ax is equivalent to that of the p-type conductive region forming the anode 13A, for example, 1e 16 cm -3 ~1e 19 cm -3 The concentration is such that it corresponds to the "electrically neutral diffusion region" in this disclosure. This makes it possible to prevent the loss of signal charge to the drain 13B.

[0098] (2-11. Variation 11) Figure 34 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1K) according to Modification 11 of the present disclosure. Similar to the above embodiment, the photodetector 1K consists of a PIN-type photodiode that applies a reverse bias between the front and back surfaces of a semiconductor substrate 11, and constitutes one pixel (unit pixel P) in a radiation image sensor (e.g., X-ray image sensor 100) or electromagnetic wave detection device that reads information about a subject (images of a subject) based on radiation (e.g., alpha rays, beta rays, gamma rays, and X-rays, etc.).

[0099] In the modified example 10 described above, an example is shown in which an overhang portion 13Ax extending in the planar direction of the semiconductor substrate 11 is provided at the end of the anode 13A that extends from the surface S1 to the back surface S2 of the semiconductor substrate 11, on the back surface S2 side of the semiconductor substrate 11, rather than on the embedded layer 14. When providing an overhang portion 13Ax in this way, it is preferable to leave a gap between the anode 13A and the drain 13B so that, for example, in a plan view, the overhang portion 13Ax and the drain 13B do not overlap. This makes it possible to prevent charge leakage from the overhang portion 13Ax to the drain 13B.

[0100] Furthermore, if the protruding portion 13Ax and the drain 13B overlap, for example, if the impurity concentration is 1e between the protruding portion 13Ax and the drain 13B 16 cm -3 ~1e 19 cm -3 A layer of impurities with a certain degree of reverse conductivity may be provided. This will allow the same effects as those described in this modified example to be obtained.

[0101] (2-12. Variation 12) Figure 35 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1L) according to Modification 12 of the present disclosure. Figure 36 schematically shows an example of the planar layout of the protruding portion 13Ax in the photodetector 1L shown in Figure 35. The photodetector 1L, as in the above embodiment, consists of, for example, a PIN-type photodiode that applies a reverse bias between the front and back surfaces of a semiconductor substrate 11, and constitutes one pixel (unit pixel P) in a radiation image sensor (e.g., X-ray image sensor 100) or electromagnetic wave detection device that reads information about a subject based on radiation (e.g., alpha rays, beta rays, gamma rays, and X-rays, etc.) (images of a subject).

[0102] In the above modified examples 10 and 11, the protruding portion 13Ax is shown to be uniformly provided on the back surface S2 side of the semiconductor substrate 11, rather than on the embedded layer 14. However, as shown in Figures 35 and 36, the protruding portion 13Ax may be provided in multiple ways, such as in a guard ring 13C, with the anode 13A in a substantially concentric or substantially concentric polygonal shape. The multiple protruding portions 13Ax1, 13Ax2, and 13Ax3 may be electrically connected to each other at one point, as shown in Figure 36, or they may be electrically connected to each other at multiple points, as shown in Figure 37A. Alternatively, the multiple protruding portions 13Ax may be formed radially, for example, as shown in Figure 37B.

[0103] Thus, in the photodetector 1L of this modified example, the total area of ​​the protruding portion 13Ax is reduced compared to the case where the protruding portion 13Ax is uniformly formed on the back surface S2 side of the semiconductor substrate 11 rather than the embedded layer 14, as in modified examples 10 and 11. As a result, the capacitance of the anode 13A is reduced, and the conversion efficiency of the signal charge to the readout voltage is improved.

[0104] (2-13. Variation 13) Figure 38 schematically shows an example of the cross-sectional configuration of the main part of a photodetector according to Modification 13 of the present disclosure. In Modification 2 described above, an example was shown in which a gate electrode 24 is provided in the insulating layer 15 between the anode 13A and the drain 13B. In this case, it is preferable to provide a Lightly Doped Drain (LDD) 22X having the following structure between the drain 13B and the n-type conductive region 21.

[0105] LDD22X has a similar configuration to LDA22, which is provided between drain 13B and n-type conductive region 21 in the above embodiment. For example, LDD22X is a region containing p-type impurities (p-type impurity region), and by providing it below gate electrode 24, it becomes less susceptible to the generation of fixed charges at the interface by X-rays. The impurity concentration of LDD22X is, for example, a peak concentration of 1e 17 cm -3 ~1e 19 cm -3 The concentration is low.

[0106] The LDD22X extends in part onto the n-type conductive region 21, forming an overlapping region below the gate electrode 24 where the n-type conductive region 21 and the LDD22X overlap. This makes it possible to efficiently transfer the dark current generated by the deterioration of the interface state of the semiconductor substrate 11 below the gate electrode 24 when irradiated with X-rays to the drain 13B.

[0107] In Figure 38, an example is shown in which the LDD22X near the interface of the surface S1 of the semiconductor substrate 11 is extended toward the anode 13A to form an overlapping region between the n-type conductivity region 21 and the LDD22X, but this is not the only example. For example, as shown in Figure 39, the n-type conductivity region 21 may be formed to a deeper position than the LDD22X, and the n-type conductivity region 21 may be extended below the LDD22X to form an overlapping region. Furthermore, when an overlapping region between the n-type conductivity region 21 and the LDD22X is formed, the formation area of ​​the gate electrode 24 can be reduced, as shown in Figure 40. This can improve the reliability of the device.

[0108] (2-14. Variation 14) Figure 41 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1M) according to Modification 14 of this disclosure. In Modification 2 described above, an example was shown in which a gate electrode 24 was provided in the insulating layer 15 between the anode 13A and the drain 13B. In this case, the n-type conductive region 21 formed near the interface of the semiconductor substrate 11 below the gate electrode 24 may be formed to a deeper position in the semiconductor substrate 11. Alternatively, as shown in Figure 41, for example, 1e 16 cm -3 ~1e 19 cm -3 A further n-type conductive region 33 having a certain impurity concentration may be provided. This makes it possible to prevent signal charges from flowing into the drain 13B.

[0109] (2-15. Variation 15) Figure 42 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1N) according to Modification 15 of the present disclosure. In Modification 2 described above, an example is shown in which a gate electrode 24 is provided within the insulating layer 15 between the anode 13A and the drain 13B. In this case, a groove 11X may be provided in the semiconductor substrate 11 around the anode 13A, and a separation portion 15X may be provided in this groove 11X, for example, by embedding the insulating layer 15.

[0110] Thus, in this modified example, a separation portion 15X made of an oxide film is provided on the semiconductor substrate 11 surrounding the anode 13A. As a result, the anode 13A and the drain 13B are physically separated, making it possible to ensure separation performance between the anode 13A and the drain 13B.

[0111] Furthermore, it is preferable to form an n-type pinning layer 34 on the semiconductor substrate 11 surrounding the isolation portion 15X. This makes it possible to prevent the generation of dark current from the interface of the semiconductor substrate 11 in contact with the isolation portion 15X.

[0112] (2-16. Variation 16) Figure 43 schematically shows an example of a cross-sectional configuration of a photodetector (photodetector 1O) according to Modification 16 of this disclosure. In Modification 15 described above, an example is shown in which a separation portion 15X made of an oxide film is provided on the semiconductor substrate 11 surrounding the anode 13A. However, the gate electrode 24 may be embedded in the groove 11X forming the separation portion 15X together with the insulating layer 15 (actually, the gate insulating layer 25). By providing a separation portion 24X formed by embedding the gate electrode 24 in the groove 11X in this way, the volume of the oxide film embedded in the semiconductor substrate 11 is reduced compared to Modification 15 described above. As a result, the increase in the interface state of the semiconductor substrate 11 in contact with the separation portion 24X after X-ray irradiation is suppressed, and the generation of dark current can be reduced.

[0113] (2-17. Variation 17) Figure 44 schematically shows an example of the cross-sectional configuration of a photodetector (photodetector 1P) according to Modification 17 of this disclosure. Similar to the above embodiment, the photodetector 1P consists of, for example, a PIN-type photodiode that applies a reverse bias between the front and back surfaces of a semiconductor substrate 11, and constitutes a single pixel (unit pixel P) in a radiation image sensor (e.g., X-ray image sensor 100) or electromagnetic wave detection device that reads information about a subject (images a subject) based on radiation (e.g., alpha rays, beta rays, gamma rays, and X-rays, etc.). In this modified example, the photodetector 1P has a vertical transfer transistor added as a pixel circuit, its gate electrode (transfer gate TRG) is embedded around the anode 13A, and the embedded layer 14 extends to the transfer gate TRG. This allows signal charge to be accumulated below the embedded layer 14, enabling complete transfer during readout. Therefore, it is possible to reduce the superposition of kTC noise on the signal charge during correlated double sampling (CDS), making it possible to realize signal detection with less readout noise.

[0114] <3. Application Examples> Figure 45 shows the functional configuration of an X-ray image sensor 100 as an example of an electronic device using the light-receiving element (for example, light-receiving element 1) described in the above embodiments and modifications 1 to 17. The X-ray image sensor 100 reads information about a subject (images the subject) based on incident radiation Rrad (for example, alpha rays, beta rays, gamma rays, X-rays, etc.). This X-ray image sensor 100 includes a pixel section (pixel area 110A), and the drive circuit (peripheral circuit section) for this pixel area 110A includes a row scanning unit 121, an A / D conversion unit 122, a column scanning unit 123, and a system control unit 124.

[0115] (Pixel area 110A) The pixel region 110A is equipped with multiple unit pixels (imaging pixels) P that generate signal charges based on radiation. The multiple unit pixels P are arranged in a matrix in two dimensions. As shown in Figure 1, the horizontal direction (row direction) within the pixel region 110A is defined as the "H" direction, and the vertical direction (column direction) is defined as the "V" direction.

[0116] (Row scanning unit 121) The row scanning unit 121 is configured to include a shift register circuit and predetermined logic circuits, as described later, and is a pixel driving unit (row scanning circuit) that drives multiple unit pixels P within the pixel area 110A in row units (horizontal line units) (line sequential scanning). Specifically, the row scanning unit 121 performs imaging operations such as readout and reset operations of each unit pixel P by line sequential scanning, for example. Line sequential scanning is performed by supplying the aforementioned row scanning signal to each unit pixel P via the readout control line Lread.

[0117] (A / D conversion unit 122) The A / D conversion unit 122 has multiple column selection units 125, one for each of the multiple (four in this case) signal lines Lsig, and performs A / D conversion (analog-to-digital conversion) based on the signal voltage (voltage corresponding to the signal charge) input via the signal line Lsig. As a result, output data Dout (imaging signal) consisting of digital signals is generated and output to the outside.

[0118] Each column selection unit 125 includes, for example, a charge amplifier 172, a capacitive element (such as a capacitor or feedback capacitance element) C1, a switch SW1, a sample-and-hold (S / H) circuit 173, a multiplexer circuit (selection circuit) 174 including four switches SW2, and an A / D converter 175, as shown in Figure 46. Of these, the charge amplifier 172, capacitive element C1, switch SW1, S / H circuit 173, and switch SW2 are provided for each signal line Lsig. The multiplexer circuit 174 and A / D converter 175 are provided for each column selection unit 125. The charge amplifier 172, capacitive element C1, and switch SW1 constitute the charge amplifier circuit.

[0119] The charge amplifier 172 is an amplifier that converts the signal charge read from the signal line Lsig into a voltage (QV conversion). In this charge amplifier 172, one end of the signal line Lsig is connected to the negative (-) input terminal, and a predetermined reset voltage Vrst is input to the positive (+) input terminal. The output terminal and the negative input terminal of the charge amplifier 172 are connected via a parallel connection circuit of a capacitive element C1 and a switch SW1, which is a feedback connection. That is, one terminal of the capacitive element C1 is connected to the negative input terminal of the charge amplifier 172, and the other terminal is connected to the output terminal of the charge amplifier 172. Similarly, one terminal of the switch SW1 is connected to the negative input terminal of the charge amplifier 172, and the other terminal is connected to the output terminal of the charge amplifier 172. The on / off state of this switch SW1 is controlled by a control signal (ampretrieval control signal) supplied from the system control unit 124 via the ampretrieval control line Lcarst.

[0120] The S / H circuit 173 is located between the charge amplifier 172 and the multiplexer circuit 174 (switch SW2), and is a circuit for temporarily holding the output voltage Vca from the charge amplifier 172.

[0121] The multiplexer circuit 174 is a circuit that selectively connects or disconnects each S / H circuit 173 and the A / D converter 175 by sequentially turning on one of the four switches SW2 in accordance with the scanning drive by the column scanning unit 123.

[0122] The A / D converter 175 is a circuit that generates and outputs the output data Dout described above by performing A / D conversion on the output voltage from the S / H circuit 173, which is input via switch SW2.

[0123] (Column scanning unit 123) The column scanning unit 123 is configured to include, for example, a shift register and an address decoder (not shown), and sequentially drives each switch SW2 in the column selection unit 125 while scanning them. Through this selective scanning by the column scanning unit 123, the signals of each unit pixel P (the output data Dout) read out via each of the signal lines Lsig are sequentially output to the outside.

[0124] (System Control Unit 124) The system control unit 124 controls the operation of the row scanning unit 121, the A / D conversion unit 122, and the column scanning unit 123. Specifically, the system control unit 124 has a timing generator that generates the various timing signals (control signals) mentioned above, and controls the drive of the row scanning unit 121, the A / D conversion unit 122, and the column scanning unit 123 based on the various timing signals generated by this timing generator. Based on the control of the system control unit 124, the row scanning unit 121, the A / D conversion unit 122, and the column scanning unit 123 each perform imaging drive (linear sequential imaging drive) for multiple unit pixels P within the pixel area 110A, thereby obtaining output data Dout from the pixel area 110A.

[0125] The embodiments and modifications 1 to 17, as well as application examples, have been described above. However, the contents of this disclosure are not limited to the embodiments described above, and various modifications are possible. For example, in the embodiments described above, examples using holes as signal charges were shown, but electrons may be used as signal charges. In that case, the conductivity types of each component will be the opposite conductivity types.

[0126] Furthermore, the layer configuration of the light-receiving element 1 described in the above embodiments is merely an example, and it may have other layers. Moreover, the material and thickness of each layer are also merely examples and are not limited to those described above. Furthermore, although the above application example uses an X-ray image sensor 100, the light-receiving element 1 described in the above embodiments can also be applied to radiation image sensors and electromagnetic wave detection devices that are not limited to X-rays.

[0127] Furthermore, the effects described herein are merely illustrative and not limiting, and other effects may also occur.

[0128] Furthermore, this disclosure can also take the following configuration. According to the technology with the following configuration, a first second conductivity type region with a different conductivity type is provided between a first first conductivity type region connected to a first electrode and a second first conductivity type region connected to a second electrode, both located near the interface of a first surface of a semiconductor substrate including a photoelectric conversion region. In addition, a fourth first conductivity type region with a lower impurity concentration than the first conductivity type region is provided between the first first conductivity type region and the first second conductivity type region. This reduces the conversion of the interface of the first surface of the semiconductor substrate to the second conductivity type after X-ray irradiation. Thus, it becomes possible to reduce the effect of the total dose effect due to X-ray irradiation. (1) A semiconductor substrate including a photoelectric conversion region, A first conductivity type region is provided at the interface of the first surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity region is provided around the first first conductivity region and connected to the second electrode, At the interface of the first surface, a third first conductivity region is provided around the second first conductivity region and is electrically floating, At the interface of the first surface, a first second conductivity type region having a different conductivity type is provided between the first first conductivity type region and the second first conductivity type region, Near the interface of the first surface, a fourth first conductivity region is provided between at least the first first conductivity region and the first second conductivity region, and the impurity concentration is lower than that of the first first conductivity region. A new light-receiving element. (2) The fourth first conductivity type region has a peak concentration of 1e 19 cm -3 The following is the light-receiving element described in (1) above. (3) The photodetector according to (1) or (2), wherein the fourth first conductivity type region is further provided between the first second conductivity type region and the second first conductivity type region at the interface of the first surface. (4) The semiconductor substrate further comprises an insulating layer provided on the first surface side and a wiring layer provided within the insulating layer. The insulating layer between the first surface and the wiring layer comprises a single layer of silicon oxide or a silicon oxide film having a thickness of at least 30 nm, and a silicon nitride film. The aforementioned A light-receiving element according to any one of (1) to (3) above, comprising a laminated film provided in this order from the first surface side. (5) A first insulating layer made of a high dielectric material having a higher dielectric constant than silicon oxide is provided on the first surface of the semiconductor substrate, A light-receiving element according to any one of (1) to (3), further comprising a first conductive film provided on the first surface side of the semiconductor substrate with at least the first insulating layer in between. (6) The first conductive film consists of multiple components, and the first insulating layer is provided individually for each of the multiple first conductive films. The light-receiving element according to (5), further comprising a second insulating layer in which a plurality of the first insulating layers and a plurality of the first conductive films are embedded and which forms air gaps between at least adjacent first insulating layers. (7) The semiconductor substrate further comprises an insulating layer provided on the first surface side, The photodetector according to any one of (1) to (3), wherein the insulating layer forms a gap between the first conductivity type region and the second conductivity type region. (8) The photodetector according to (7), wherein the semiconductor substrate has a recess on the first surface, and the first conductive type region is provided in the recess. (9) The photodetector according to any one of (1) to (8), wherein the third first conductivity type region is provided in a plurality of substantially concentric rectangular or substantially concentric circular shapes with respect to the first first conductivity type region, and adjacent third first conductivity type regions are uniformly spaced apart in all formation regions. (10) An insulating layer provided on the first surface side of the semiconductor substrate, The photodetector according to any one of (1) to (9), further comprising a second conductive film provided wider than the third first conductivity region so as to cover at least a portion of the third first conductivity region with the insulating layer in between, and electrically connected to the third first conductivity region through an opening provided in the insulating layer. (11) The light-receiving element according to (10), wherein the second conductive film extends outwards from the third first conductive type region toward the first first conductive type region. (12) The photodetector according to any one of (1) to (11), wherein the third first conductivity type region is provided in a plurality of substantially concentric rectangular or substantially concentric circular shapes with respect to the first first conductivity type region, and further comprises a second second conductivity type region provided between adjacent third first conductivity type regions near the interface of the first surface. (13) The photodetector according to (12), wherein the third first conductivity region has a fifth first conductivity region on both sides having a lower impurity concentration than the third first conductivity region. (14) The photodetector according to (12) or (13), wherein the second conductivity type region is further provided near the interface of the first surface between the second first conductivity type region and the third first conductivity type region. (15) The photodetector according to (12) or (13), wherein the second second conductivity type region is provided in contact with the third first conductivity type region on the side opposite to the second first conductivity type region. (16) A light-receiving element according to any one of (12) to (15), wherein a sixth first conductivity region having a lower impurity concentration than the third first conductivity region is further provided near the interface of the first surface between the second second conductivity region and the third first conductivity region on the second first conductivity region side. (17) The photodetector according to (15) or (16), wherein the second second conductivity region, each provided in contact with a plurality of third first conductivity region, is wider than the second second conductivity region that is in contact with the third first conductivity region on the opposite side from the second first conductivity region. (18) The photodetector according to (15) or (16), wherein the second second conductivity region, each provided in contact with a plurality of third first conductivity region, has a higher impurity concentration in the second second conductivity region that is in contact with the third first conductivity region on the opposite side from the second first conductivity region. (19) On the first surface side of the semiconductor substrate including multiple wiring layers with an insulating layer in between. It further has a multilayer wiring layer, The plurality of wiring layers include a first wiring layer extending above the third first conductivity type region. The first wiring layer is formed as the second or subsequent layer from the first surface side among the plurality of wiring layers, and is a light-receiving element according to any one of (12) to (18). (20) The semiconductor substrate further comprises a third second conductivity region embedded in the substrate facing the second first conductivity region and the third first conductivity region, and a plurality of pixels each having the first first conductivity region, the second first conductivity region, and the third first conductivity region. A light-receiving element according to any one of (1) to (19), wherein a fourth second conductivity type region is further provided near the interface of the first surface between adjacent pixels. (twenty one) The semiconductor substrate further comprises a third second conductivity region embedded in the substrate facing the second first conductivity region and the third first conductivity region, and a plurality of pixels each having the first first conductivity region, the second first conductivity region, and the third first conductivity region. The photodetector according to any one of (1) to (19), wherein the third first conductivity type regions provided in adjacent pixels are connected to each other via a seventh first conductivity type region having an impurity concentration equivalent to that of the third first conductivity type region, at least in part. (twenty two) The semiconductor substrate further comprises a third second conductivity region embedded in the substrate facing the second first conductivity region and the third first conductivity region, and a plurality of pixels each having the first first conductivity region, the second first conductivity region, and the third first conductivity region. The photodetector according to any one of (1) to (19), wherein the third first conductivity type regions of adjacent pixels are electrically connected to each other via wiring provided on the first surface of the semiconductor substrate. (twenty three) The photodetector according to (22), wherein the first conductivity type region extends toward a second surface facing the first surface and extends in the in-plane direction of the semiconductor substrate with the third conductivity type region in between. (twenty four) A photodetector according to any one of (1) to (23), further having an electrically neutral diffusing region that extends from the bottom surface of the first conductivity type region toward the second surface facing the first surface, and extends in the in-plane direction of the semiconductor substrate to a position that does not overlap with the second conductivity type region. (twenty five) The semiconductor substrate comprises a third second conductivity region embedded and formed within the substrate facing the second first conductivity region and the third first conductivity region, A light-receiving element according to any one of (1) to (24), further comprising: a plurality of electrically neutral diffusion regions provided in a substantially concentric rectangular shape around the first conductivity region in a plan view, with the third conductivity region in between, extending from the bottom surface of the first conductivity region toward the second surface on the side facing the first surface of the first conductivity region; and electrically connected to each other. (26) The present invention further comprises a first conductive film provided above the first surface between at least the first conductive type region and the second first conductive type region, A light-receiving element according to any one of (3) to (25), wherein between the second first conductivity type region and the fourth first conductivity type region provided between the first second conductivity type region and the second first conductivity type region, the fourth first conductivity type region has an overlapping region on the second first conductivity type region, with the first surface of the fourth first conductivity type region extending toward the first first conductivity type region. (27) The present invention further comprises a first conductive film provided above the first surface between at least the first conductive type region and the second first conductive type region, The photodetector according to any one of (1) to (25), wherein the first second conductivity type region is formed from the interface of the first surface to a position deeper than the second first conductivity type region. (28) A first conductive film provided above the first surface between the first first conductive type region and the second first conductive type region, The photodetector according to any one of (1) to (27), further comprising a separation portion between the first first conductivity type region and the second first conductivity type region, the separation portion including an oxide film embedded and formed on the first surface. (29) A light-receiving element according to any one of (1) to (28), further comprising a first conductive film provided above the first surface between the first first conductivity region and the second first conductivity region, with a portion of it protruding into the semiconductor substrate between the first first conductivity region and the second first conductivity region. (30) A vertical transistor that transfers charge generated by photoelectric conversion to the first surface between the first first conductivity type region and the second first conductivity type region, The semiconductor substrate further comprises a second first conductivity region and a third second conductivity region embedded and formed within the substrate facing the third first conductivity region. The photodetector according to any one of (1) to (28), wherein the gate of the vertical transistor extends within the semiconductor substrate from the first surface of the semiconductor substrate toward the second surface opposite the first surface and is in contact with the side surface of the third second conductivity type region. (31) It comprises multiple photodetectors that generate signal charges based on X-rays, The aforementioned light-receiving element is Photoelectric conversion region A semiconductor substrate containing, A first conductivity type region is provided at the interface of the first surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity region is provided around the first first conductivity region and connected to the second electrode, At the interface of the first surface, a third first conductivity region is provided around the second first conductivity region and is electrically floating, At the interface of the first surface, a first second conductivity type region having a different conductivity type is provided between the first first conductivity type region and the second first conductivity type region, Near the interface of the first surface, a fourth first conductivity region is provided between at least the first first conductivity region and the first second conductivity region, and the impurity concentration is lower than that of the first first conductivity region. X-ray imaging sensor. (32) A pixel region in which multiple pixels are arranged, It has a peripheral region provided around the aforementioned pixel region, The semiconductor substrate is an X-ray imaging sensor according to (31), wherein the semiconductor substrate has a depletion region in the pixel region and a neutral region in the peripheral region. (33) The X-ray imaging sensor according to (32), wherein the photodetector is provided for each of the plurality of pixels and is a pn junction type photodetector that applies a reverse bias between the first surface of the semiconductor substrate and the second surface facing the first surface. (34) Equipped with an X-ray imaging sensor, The aforementioned X-ray imaging sensor has a plurality of photodetectors that generate signal charges based on X-rays, The aforementioned light-receiving element is Photoelectric conversion region A semiconductor substrate containing, A first conductivity type region is provided at the interface of the first surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity region is provided around the first first conductivity region and connected to the second electrode, At the interface of the first surface, a third first conductivity region is provided around the second first conductivity region and is electrically floating, At the interface of the first surface, a first second conductivity type region having a different conductivity type is provided between the first first conductivity type region and the second first conductivity type region, Near the interface of the first surface, a fourth first conductivity region is provided between at least the first first conductivity region and the first second conductivity region, and the impurity concentration is lower than that of the first first conductivity region. Electronic devices equipped with these features. (35 ) light A semiconductor substrate including an electrical conversion region, A first conductivity type region is provided at the interface of the first surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity region is provided around the first first conductivity region and connected to the second electrode, At the interface of the first surface, a third first conductivity region is provided around the second first conductivity region and is electrically floating, A conductive film provided above the first surface between at least the first conductive type region and the second first conductive type region, At the interface of the first surface, a first second conductivity type region having a different conductivity type is provided between the first first conductivity type region and the second first conductivity type region, At the interface of the first surface, a fourth first conductivity region is provided between the second first conductivity region and the first second conductivity region, and a portion of it extends over the second first conductivity region, and the impurity concentration is lower than that of the second first conductivity region. A new light-receiving element. (36) A semiconductor substrate including a photoelectric conversion region, A first conductivity type region is provided at the interface of the first surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity region is provided around the first first conductivity region and connected to the second electrode, At the interface of the first surface, a third first conductivity region is provided around the second first conductivity region and is electrically floating, A conductive film provided above the first surface between the first first conductivity type region and the second first conductivity type region, At the interface of the first surface, between the first first conductivity type region and the second first conductivity type region, a first second conductivity type region is formed to a position deeper than the second first conductivity type region and having a different conductivity type. At the interface of the first surface, a fourth first conductivity region is provided between the first first conductivity region and the second first conductivity region, and between the second first conductivity region and the first second conductivity region, and the impurity concentration is lower than that of the second first conductivity region. A new light-receiving element.

[0129] This application claims priority based on Japanese Patent Application No. 2021-112167, filed with the Japan Patent Office on 6 July 2021, and all contents of that application are incorporated herein by reference.

[0130] Those skilled in the art will understand that various modifications, combinations, subcombinations, and changes can be conceived depending on design requirements and other factors, and that these fall within the scope of the attached claims and their equivalents.

Claims

1. A semiconductor substrate including a photoelectric conversion region, A first conductivity type region is provided at the interface of the first surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity type region is provided around the first first conductivity type region and connected to the second electrode, At the interface of the first surface, a third first conductivity region is provided around the second first conductivity region and is electrically floating, At the interface of the first surface, a first second conductivity type region having a different conductivity type is provided between the first first conductivity type region and the second first conductivity type region, Near the interface of the first surface, a fourth first conductivity region is provided between at least the first first conductivity region and the first second conductivity region, and the impurity concentration is lower than that of the first first conductivity region. A new light-receiving element.

2. The fourth first conductivity type region has a peak concentration of 1e １９ cm －３ The light-receiving element according to claim 1, which is as follows:

3. The light-receiving element according to claim 1, wherein the fourth first conductivity type region is further provided between the first second conductivity type region and the second first conductivity type region at the interface of the first surface.

4. The semiconductor substrate further comprises an insulating layer provided on the first surface side and a wiring layer provided within the insulating layer. The photodetector according to claim 1, wherein the insulating layer between the first surface and the wiring layer is a laminated film in which a single layer of silicon oxide or a silicon oxide film having a thickness of at least 30 nm and a silicon nitride film are provided in this order from the first surface side.

5. A first insulating layer made of a high dielectric material having a higher dielectric constant than silicon oxide is provided on the first surface of the semiconductor substrate, The light-receiving element according to claim 1, further comprising a first conductive film provided on the first surface side of the semiconductor substrate with at least the first insulating layer in between.

6. The first conductive film consists of multiple components, and the first insulating layer is provided individually for each of the multiple first conductive films. The light-receiving element according to claim 5, further comprising a second insulating layer in which a plurality of the first insulating layers and a plurality of the first conductive films are embedded and which forms voids between at least adjacent first insulating layers.

7. The semiconductor substrate further comprises an insulating layer provided on the first surface side, The photodetector according to claim 1, wherein the insulating layer has a gap between the first conductivity type region and the second conductivity type region.

8. The photodetector according to claim 7, wherein the semiconductor substrate has a recess on the first surface, and the first conductive type region is provided in the recess.

9. The photodetector according to claim 1, wherein the third first conductivity type region is provided in a plurality of substantially concentric rectangular or substantially concentric circular shapes with respect to the first first conductivity type region, and adjacent third first conductivity type regions have a uniform spacing in all formation regions.

10. An insulating layer provided on the first surface side of the semiconductor substrate, The light-receiving element according to claim 1, further comprising a second conductive film that is wider than the third first conductivity region and covers at least a portion of the third first conductivity region with respect to the insulating layer in between, and is electrically connected to the third first conductivity region through an opening provided in the insulating layer.

11. The light-receiving element according to claim 10, wherein the second conductive film extends outwards from the third first conductive region toward the first first conductive region.

12. The photodetector according to claim 1, wherein the third first conductivity type region is provided in a plurality of substantially concentric rectangular or substantially concentric circular shapes with respect to the first first conductivity type region, and further comprises a second second conductivity type region provided between adjacent third first conductivity type regions near the interface of the first surface.

13. The photodetector according to claim 12, wherein the third first conductivity type region has a fifth first conductivity type region on both sides having a lower impurity concentration than the third first conductivity type region.

14. The light-receiving element according to claim 12, wherein the second conductivity type region is further provided near the interface of the first surface between the second first conductivity type region and the third first conductivity type region.

15. The light-receiving element according to claim 12, wherein the second conductivity type region is provided in contact with the third conductivity type region on the opposite side from the second conductivity type region.

16. The photodetector according to claim 12, wherein a sixth first conductivity region having a lower impurity concentration than the third first conductivity region is further provided near the interface of the first surface between the second second conductivity region and the third first conductivity region on the second first conductivity region side.

17. The light-receiving element according to claim 15, wherein the second second conductivity region, which is provided in contact with each of the multiple third first conductivity region, is formed to be wider in the second second conductivity region that is in contact with the third first conductivity region provided on the opposite side from the second first conductivity region.

18. The photodetector according to claim 15, wherein the second second conductivity region, each provided in contact with a plurality of third first conductivity region, has a higher impurity concentration in the second second conductivity region that is in contact with the third first conductivity region located on the opposite side from the second first conductivity region.

19. The semiconductor substrate further has a multilayer wiring layer on the first surface side, which includes a plurality of wiring layers laminated with an insulating layer in between. The plurality of wiring layers include a first wiring layer extending above the third first conductivity type region. The light-receiving element according to claim 12, wherein the first wiring layer is formed as the second or subsequent layer from the first surface side among the plurality of wiring layers.

20. The semiconductor substrate further comprises a third second conductivity region embedded in the substrate facing the second first conductivity region and the third first conductivity region, and a plurality of pixels each having the first first conductivity region, the second first conductivity region, and the third first conductivity region. The photodetector according to claim 1, wherein a fourth second conductivity type region is further provided near the interface of the first surface between adjacent pixels.

21. The semiconductor substrate further comprises a third second conductivity region embedded in the substrate facing the second first conductivity region and the third first conductivity region, and a plurality of pixels each having the first first conductivity region, the second first conductivity region, and the third first conductivity region. The photodetector according to claim 1, wherein the third first conductivity type regions provided in adjacent pixels are connected to each other via a seventh first conductivity type region having an impurity concentration equivalent to that of the third first conductivity type region, at least in part.

22. The semiconductor substrate further comprises a third second conductivity region embedded in the substrate facing the second first conductivity region and the third first conductivity region, and a plurality of pixels each having the first first conductivity region, the second first conductivity region, and the third first conductivity region. The photodetector according to claim 1, wherein the third first conductivity type regions of adjacent pixels are electrically connected to each other via wiring provided on the first surface of the semiconductor substrate.

23. The photodetector according to claim 22, wherein the first conductivity type region extends toward a second surface facing the first surface and extends in the in-plane direction of the semiconductor substrate with the third conductivity type region in between.

24. The photodetector according to claim 1, further comprising an electrically neutral diffusing region that extends from the bottom surface of the first conductivity type region toward the second surface facing the first surface toward the second surface, and that extends in the in-plane direction of the semiconductor substrate to a position that does not overlap with the second conductivity type region.

25. The semiconductor substrate comprises a third second conductivity region embedded and formed within the substrate facing the second first conductivity region and the third first conductivity region, The photodetector according to claim 1, further comprising: a plurality of electrically neutral diffusion regions that extend from the bottom surface of the first conductivity region toward the second surface facing the first surface toward the second surface, with the third conductivity region in between, arranged in a substantially concentric rectangular shape around the first conductivity region in a plan view, and electrically connected to one another in the in-plane direction of the semiconductor substrate.

26. The present invention further comprises a first conductive film provided above the first surface between at least the first conductive type region and the second first conductive type region, The light-receiving element according to claim 3, wherein the second first conductivity type region and the fourth first conductivity type region provided between the first second conductivity type region and the second first conductivity type region have an overlapping region on the second first conductivity type region in which the fourth first conductivity type region extends its first surface toward the first first conductivity type region.

27. The present invention further comprises a first conductive film provided above the first surface between at least the first conductive type region and the second first conductive type region, The photodetector according to claim 1, wherein the first second conductivity type region is formed from the interface of the first surface to a position deeper than the second first conductivity type region.

28. A first conductive film provided above the first surface between the first first conductive type region and the second first conductive type region, The photodetector according to claim 1, further comprising a separation portion between the first first conductivity type region and the second first conductivity type region, the separation portion including an oxide film embedded and formed on the first surface.

29. The photodetector according to claim 1, further comprising a first conductive film provided above the first surface between the first first conductivity region and the second first conductivity region, with a portion of it protruding into the semiconductor substrate between the first first conductivity region and the second first conductivity region.

30. A vertical transistor that transfers charge generated by photoelectric conversion to the first surface between the first first conductivity type region and the second first conductivity type region, The semiconductor substrate further comprises a second first conductivity region and a third second conductivity region embedded and formed within the substrate facing the third first conductivity region. The photodetector according to claim 1, wherein the gate of the vertical transistor extends within the semiconductor substrate from the first surface of the semiconductor substrate toward the second surface opposite the first surface and is in contact with the side surface of the third second conductivity type region.

31. It is equipped with multiple photodetectors that generate signal charges based on X-rays, The aforementioned light-receiving element is A semiconductor substrate including a photoelectric conversion region, A first conductivity type region is provided at the interface of the first surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity type region is provided around the first first conductivity type region and connected to the second electrode, At the interface of the first surface, a third first conductivity region is provided around the second first conductivity region and is electrically floating, At the interface of the first surface, a first second conductivity type region having a different conductivity type is provided between the first first conductivity type region and the second first conductivity type region, Near the interface of the first surface, a fourth first conductivity region is provided between at least the first first conductivity region and the first second conductivity region, and the impurity concentration is lower than that of the first first conductivity region. X-ray imaging sensor.

32. A pixel region in which multiple pixels are arranged, It has a peripheral region provided around the aforementioned pixel region, The X-ray imaging sensor according to claim 31, wherein the semiconductor substrate has a depletion region in the pixel region and a neutral region in the peripheral region.

33. The X-ray imaging sensor according to claim 32, wherein the photodetector is provided for each of the plurality of pixels and is a pn junction type photodetector that applies a reverse bias between the first surface of the semiconductor substrate and the second surface facing the first surface.

34. Equipped with an X-ray imaging sensor, The aforementioned X-ray imaging sensor has a plurality of photodetectors that generate signal charges based on X-rays, The aforementioned light-receiving element is A semiconductor substrate including a photoelectric conversion region, A first conductivity type region is provided at the interface of the first surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity type region is provided around the first first conductivity type region and connected to the second electrode, At the interface of the first surface, a third first conductivity region is provided around the second first conductivity region and is electrically floating, At the interface of the first surface, a first second conductivity type region having a different conductivity type is provided between the first first conductivity type region and the second first conductivity type region, Near the interface of the first surface, a fourth first conductivity region is provided between at least the first first conductivity region and the first second conductivity region, and the impurity concentration is lower than that of the first first conductivity region. Electronic devices equipped with these features.

35. A semiconductor substrate including a photoelectric conversion region, A first conductivity type region is provided at the interface of the first surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity type region is provided around the first first conductivity type region and connected to the second electrode, At the interface of the first surface, a third first conductivity region is provided around the second first conductivity region and is electrically floating, A conductive film provided above the first surface between at least the first conductive type region and the second first conductive type region, At the interface of the first surface, a first second conductivity type region having a different conductivity type is provided between the first first conductivity type region and the second first conductivity type region, At the interface of the first surface, a fourth first conductivity region is provided between the second first conductivity region and the first second conductivity region, and a portion of it extends over the second first conductivity region, and has a lower impurity concentration than the second first conductivity region. A new light-receiving element.

36. A semiconductor substrate including a photoelectric conversion region, A first conductivity type region is provided at the interface of the first surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity type region is provided around the first first conductivity type region and connected to the second electrode, At the interface of the first surface, a third first conductivity region is provided around the second first conductivity region and is electrically floating, A conductive film provided above the first surface between the first first conductivity type region and the second first conductivity type region, At the interface of the first surface, between the first first conductivity type region and the second first conductivity type region, a first second conductivity type region is formed to a position deeper than the second first conductivity type region and having a different conductivity type. At the interface of the first surface, a fourth first conductivity region is provided between the first first conductivity region and the second first conductivity region, and between the second first conductivity region and the first second conductivity region, and the impurity concentration is lower than that of the second first conductivity region. A new light-receiving element.

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