Photodiode array

Abstract

A photodiode array (1) comprising a plurality of photodiodes (PD1, PD2, PD3, PD4) formed in a semiconductor substrate (2), each of the photodiodes (PD1, PD2, PD3, PD4) comprising: a first semiconductor region (3) of a first conductivity type, and which is provided in the semiconductor carrier material (2); a second semiconductor region (4) of the first conductivity type, which is provided with respect to the first semiconductor region (3) on a surface side (21) of the semiconductor substrate (2) and has a higher impurity concentration than an impurity concentration of the first semiconductor region (3); at least one third semiconductor region (5) of a second conductivity type, which is provided with respect to the first semiconductor region (3) on the one surface side (21) such that it surrounds the second semiconductor region (4) separately from the second semiconductor region (4) and forms a light detection region together with the first semiconductor region (3); and a breakthrough electrode (81a, 81b) which is provided with a breakthrough opening (9A, 9B) which passes through one surface (21) and the other surface (22) of the semiconductor carrier material (2) so that it passes through the first semiconductor region (3) and the second semiconductor region (4), and is electrically connected to the at least one third semiconductor region (5), and wherein the second semiconductor region (4) is surrounded by the at least one third semiconductor region (5) which is electrically connected to the breakdown electrode (81a, 81b) provided in the same breakdown opening (9A, 9B) passing through the second semiconductor region (4).

Description

Technical area

[0001] The present invention relates to a photodiode array. State of the art

[0002] For example, Patent Literature 1 describes a photodiode array used in a CT (computed tomography) device or the like. In the photodiode array of Patent Literature 1, P forming a light detection area are + -type semiconductor regions are arranged two-dimensionally on the incident surface side of an n-type semiconductor substrate. An electrode is connected to each of the P + -type semiconductor regions. Each of the electrodes is connected to the rear surface side on the side opposite the incident surface via a + -type semiconductor regions are pulled out according to the provided breakthrough opening. The P +-type semiconductor region and the through hole are alternately arranged in the semiconductor substrate along a predetermined direction. Literature listPatent literature

[0003] [Patent Literature 1] Japanese Unexamined Patent Application Publication (Translation of PCT Application) JP 2005-533587 A

[0004] US 2004 / 0129992 A1 describes a photodiode array in which the breakdown electrodes extend across through-holes between multiple photodiodes. A single breakdown electrode is connected to multiple third semiconductor regions belonging to different photodiodes.

[0005] US 2010 / 0200940 A1 describes a photodiode array with active regions on both sides of a substrate. Electrical connection is established via electrically isolated conductive vias that extend through the substrate to enable vertical integration of multiple detector modules.

[0006] US 2009 / 0108391 A1 describes an image recording system with P-type and N-type semiconductor layers. The through-hole plating is achieved through precisely placed vias that only pass through semiconductor material of one conductivity type to avoid damage to pn junctions. Summary of the inventionTechnical problem

[0007] In the photodiode array of Patent Literature 1, a sufficient distance for providing the breakthrough opening between the adjacent P + -type semiconductor regions are necessary. For this reason, there may be concerns about a reduced aperture ratio. Additionally, improvements in a variety of reliability aspects, such as electrical properties, are needed in the photodiode array.

[0008] An object of the present invention is to provide a photodiode array suitable for improving an aperture ratio and reliability. Solution to the task

[0009] The above-mentioned problem is solved by the subject matter of the independent claim. Examples and technical descriptions of devices, products, and / or methods in the description and / or drawings that are not covered by the claims are not presented as embodiments of the invention, but rather as prior art or as examples that facilitate understanding of the invention. According to one aspect of the present invention, a photodiode array is provided, comprising a plurality of photodiodes formed in a semiconductor substrate, each of the photodiodes comprising a first semiconductor region of a first conductivity type, and which is provided in the semiconductor substrate;a second semiconductor region of the first conductivity type, which is provided on one surface side of the semiconductor substrate with respect to the first semiconductor region and has a higher impurity concentration than an impurity concentration of the first semiconductor region; a third semiconductor region of a second conductivity type, which is provided on the one surface side of the first semiconductor region so as to surround the second semiconductor region separately from the second semiconductor region and, together with the first semiconductor region, forms a light detection region; and a through-hole electrode provided with a through-hole opening passing through one surface and the other surface of the semiconductor substrate so as to pass through the first semiconductor region and the second semiconductor region, and is electrically connected to the third semiconductor region.

[0010] In the photodiode array, in each of the photodiodes, the through-hole passes through the first and second semiconductor regions, and the second semiconductor region is surrounded by the third semiconductor region. The third semiconductor region, together with the first semiconductor region, forms the light-detecting region. Here, in each photodiode, which is a pixel, the through-hole is surrounded by the light-detecting region. Therefore, it is possible to reduce a distance between adjacent photodiodes. Thus, it is possible to improve an aperture ratio. Furthermore, the second semiconductor region through which the through-hole passes has a higher impurity concentration than the impurity concentration of the first semiconductor region. Therefore, a surface leakage current generated in the inner wall of the through-hole and directed to the light-detecting region through the second semiconductor region can be reduced.Thus, it is possible to improve electrical properties. In addition, since the second semiconductor region through which the through hole passes has a higher impurity concentration than the impurity concentration of the first semiconductor region, it is possible to reduce a variety of stresses occurring in the through hole. Thus, it is possible to improve its strength. Furthermore, the second semiconductor region and the third semiconductor region are separated from each other. Therefore, it is possible to prevent short-circuiting between the second semiconductor region and the third semiconductor region and improve electrical properties.

[0011] A portion of the first semiconductor region may be provided between the second semiconductor region and the third semiconductor region so as to surround the second semiconductor region. According to such a configuration, it is possible to improve electrical properties.

[0012] A distance between an inner boundary and an outer boundary of the second semiconductor region may be greater than a distance between the outer boundary of the second semiconductor region and an inner boundary of the third semiconductor region. According to such a configuration, various stresses occurring in the through-hole can be reduced much more effectively by the second semiconductor region.

[0013] The inner boundary of the third semiconductor region may surround an opening of the through hole on the other surface side when viewed from a thickness direction of the semiconductor substrate. According to such a configuration, the third semiconductor region is provided in a region positioned further outward from the through hole when viewed from the thickness direction of the semiconductor substrate. Therefore, for example, by forming a bump electrode or the like within the through hole, it is possible to reduce stress applied to the third semiconductor region forming the light detection region.

[0014] Each of the electrodes may include a contact electrode formed on one surface and electrically connecting the third semiconductor region and the through-hole electrode. An outer boundary of the contact electrode may surround the opening of the through-hole on the other surface side when viewed from the thickness direction of the semiconductor substrate. According to such a configuration, the contact electrode is provided over the region of the inside and outside of the through-hole when viewed from the thickness direction of the semiconductor substrate. Therefore, it is possible to improve the strength in the vicinity of the through-hole.

[0015] The opening of the through-hole on one surface side may have a circular shape. According to such a configuration, for example, if the bump electrode is formed within the through-hole, or the like, it is possible to prevent stress concentration from occurring in the through-hole. Advantageous effects of the invention

[0016] According to the present invention, it is possible to provide a photodiode array capable of improving an aperture ratio and reliability. Short description of the characters Fig. 1 is a plan view illustrating a photodiode array according to an embodiment of the present invention. Fig. Fig. 2 is a plan view showing a photodiode of the photodiode array of Fig. 1 represents. Fig. Figure 3 is a section view taken along a line III-III of Fig. 2 is taken. Fig. 4 is a cross-sectional view showing a process of a method of manufacturing the photodiode array of Fig. 1 represents. Fig. Fig. 5 is a cross-sectional view showing a process of a method of manufacturing the photodiode array of Fig. 1 represents. Fig. 6 is a cross-sectional view showing a process of a method of manufacturing the photodiode array of Fig. 1 represents. Fig. Fig. 7 is a cross-sectional view showing a process of a method of manufacturing the photodiode array of Fig. 1 represents. Fig. Fig. 8 is a cross-sectional view showing a process of a method for manufacturing the photodiode array of Fig. 1 represents. Fig. 9 is a cross-sectional view showing a process of a method of manufacturing the photodiode array of Fig. 1 represents. Fig. 10 is a cross-sectional view showing a process of a method of manufacturing the photodiode array of Fig. 1 represents. Fig. 11 is a cross-sectional view showing a process of a method of manufacturing the photodiode array of Fig. 1 represents. Fig. 12 is a cross-sectional view showing a process of a method of manufacturing the photodiode array of Fig. 1 represents. Fig. Fig. 13 is a sectional view showing a portion of a CT apparatus on which the photodiode array of Fig. 1 is applied. Fig. 14 is a cross-sectional view illustrating a photodiode of a photodiode array according to another embodiment of the present invention. Fig. 15 is a plan view illustrating a photodiode of a photodiode array according to another embodiment of the present invention. Fig. 16 is a plan view illustrating a photodiode of a photodiode array according to another embodiment of the present invention. Description of embodiments

[0017] A photodiode array according to an embodiment will be described in detail below with reference to the accompanying figures. However, the same or equivalent components are denoted by the same reference numerals and symbols, and the descriptions thereof will not be repeated. [Photodiode array]

[0018] As in Fig. 1 shows a photodiode array 1 used in, for example, a CT device or the like. The photodiode array 1 comprises a plurality of photodiodes PD1 formed in a semiconductor substrate 2.

[0019] The semiconductor substrate 2 has a rectangular shape when viewed from a top view. As shown in Fig. As shown in Figure 3, the semiconductor substrate 2 has a surface (one surface) 21 and a back surface (the other surface) 22 opposite each other. An insulating film f1 and an insulating film f3 are formed on the surface 21 in this order from the surface 21. An insulating film f4 and an insulating film f5 are formed on the back surface 22 in this order from the back surface 22. As each insulating film, an SiO2 film, a SiN film, or the like is formed.

[0020] As in Fig. 1, photodiodes PD1 are arranged two-dimensionally on the semiconductor substrate 2. Each of the photodiodes PD1 functions as a pixel. As shown in Fig. 3, the photodiode PD1 comprises a first semiconductor region 3, a second semiconductor region 4, a third semiconductor region 5, a fourth semiconductor region 6, a fifth semiconductor region 7, a breakdown electrode 81a, a contact electrode 82a and a terminal electrode 83a.

[0021] The first semiconductor region 3 comprises a central portion in the thickness direction of the semiconductor substrate 2. The first semiconductor region 3 has a rectangular shape when viewed from the thickness direction of the semiconductor substrate 2. The first semiconductor region 3 is provided over the entire photodiode PD1 in the central portion in the thickness direction of the semiconductor substrate 2. The first semiconductor regions 3 and 3 of the adjacent photodiodes PD1 and PD1 are integrally formed. The first semiconductor region 3 is an n - -type semiconductor region. The first semiconductor region is formed, for example, from Si or the like. A substrate electrode, not shown, is connected to the first semiconductor region 3.

[0022] The second semiconductor region 4 is provided on the surface 21 side of the semiconductor substrate 2 with respect to the first semiconductor region 3. The second semiconductor region 4 has an annular shape such that the outer boundary thereof has a circular shape and the inner boundary thereof has a rectangular shape (specifically, a square shape) when viewed from the thickness direction of the semiconductor substrate 2. The second semiconductor region 4 may have other annular shapes (such as a polygonal annular shape such as a quadrangular annular shape, a circular annular shape, and the like). That is, the annular shape refers to a uniform shape in which any region is surrounded so as to be closed.The inner boundary of the second semiconductor region 4 forms an opening of a through hole 9A (described later) on the side of the surface 21. The second semiconductor region 4 is an n. + -type semiconductor region and has a higher impurity concentration than the impurity concentration of the first semiconductor region 3. The second semiconductor region 4 is formed, for example, by diffusing an n-type impurity in Si or the like.

[0023] The third semiconductor region 5 is provided with respect to the first semiconductor region 3 on the side of the surface 21 of the semiconductor substrate 2. The third semiconductor region 5 is separated from the second semiconductor region 4 and surrounds the second semiconductor region 4. The third semiconductor region 5 has an annular shape such that the outer boundary thereof has a rectangular shape and the inner boundary thereof has a round shape when viewed from the thickness direction of the semiconductor substrate 2. The third semiconductor region 5 may have other annular shapes. The third semiconductor region 5 is a p +-type semiconductor region. The third semiconductor region 5 and the first semiconductor region 3 form a pn interface and constitute a light detection region of the photodiode PD1. The third semiconductor region 5 is formed, for example, by diffusing a p-type impurity in silicon or the like. The second semiconductor region 4 is designed to be deeper than the third semiconductor region 5.

[0024] A first partial region 31, which is a partial region of the first semiconductor region 3, is present between the second semiconductor region 4 and the third semiconductor region 5. When viewed from the thickness direction of the semiconductor substrate 2, the first partial region 31 surrounds the second semiconductor region 4 and is surrounded by the third semiconductor region 5. The first partial region 31 has a circular annular shape when viewed from the thickness direction of the semiconductor substrate 2. The first partial region 31 may have other annular shapes.

[0025] The fourth semiconductor region 6 is provided on the surface 21 side of the semiconductor substrate 2 with respect to the first semiconductor region 3. When viewed from the thickness direction of the semiconductor substrate 2, the fourth semiconductor region 6 has a rectangular annular shape, which is larger than that of the third semiconductor region 5, and surrounds the third semiconductor region 5. The fourth semiconductor region 6 may have other annular shapes. The fourth semiconductor region 6 is separated from the third semiconductor region 5. A second partial region 32, which is a partial region of the first semiconductor region 3, is present between the third semiconductor region 5 and the fourth semiconductor region 6. The second partial region 32 has a rectangular annular shape when viewed from the thickness direction of the semiconductor substrate 2. The second partial region 32 may have other annular shapes.The fourth semiconductor regions 6 and 6 of the adjacent photodiodes PD1 and PD1 are formed in one piece.

[0026] The fourth semiconductor region 6 is an n + -type semiconductor region and has a higher impurity concentration than the impurity concentration of the first semiconductor region 3. The fourth semiconductor region 6 is formed, for example, by diffusing an n-type impurity in silicon. The fourth semiconductor region 6 functions as a channel stopper, separating the adjacent photodiodes PD1 and PD1 from each other. The fourth semiconductor region 6 is grounded via an electrode, which is not shown.

[0027] The fifth semiconductor region 7 is provided with respect to the first semiconductor region 3 on the rear surface 22 side of the semiconductor substrate 2. The fifth semiconductor region 7 is formed over the entire photodiode PD1 on the rear surface 22 side. The fifth semiconductor regions 7 and 7 of the adjacent photodiodes PD1 and PD1 are formed integrally. The fifth semiconductor region 7 is an n + -type semiconductor region, and has a higher impurity concentration than the impurity concentration of the first semiconductor region 3. The fifth semiconductor region 7 is formed, for example, by diffusing an n-type impurity in silicon. The first semiconductor region 3 and the fifth semiconductor region 7 can be formed, for example, by growing an n - -type epitaxial layer on n + -type Si, wherein the epitaxial layer has an impurity concentration lower than that of Si.

[0028] The through-hole 9A, which penetrates the surface 21 and the rear surface 22, is provided in the semiconductor substrate 2. The through-hole 9A penetrates the first semiconductor region 3, the second semiconductor region 4, and the fifth semiconductor region 7. The opening comprises a portion extending from the surface 21 side to the rear surface 22 side. The through-hole 9A comprises a small opening portion 91a located on the surface 21 side and a large opening portion 92a located on the rear surface 22 side.

[0029] The small opening portion 91a penetrates the insulating film f1. The small opening portion 91a has a cylindrical shape. The opening of the through-hole 9A on the surface 21 side has a circular shape.

[0030] The large opening portion 92a passes through the first semiconductor region 3 and the second semiconductor region 4. The large opening portion 92a extends from the surface 21 side to the rear surface 22 side and has a tapered shape. Specifically, the large opening portion 92a has a four-sided frustum shape. The opening of the through-hole 9A on the rear surface 22 side has a rectangular shape (specifically, a square shape). The inner wall of the large opening portion 92a and the surface 21 form an angle of approximately 55°. The inner wall of the large opening portion 92a and the rear surface 22 form an angle of approximately 125°. The top surface of the large opening portion 92a is larger than the diameter of the small opening portion 91a.The small opening portion 91a and the large opening portion 92a are arranged coaxially to each other.

[0031] An insulating film f6 is formed on the inner wall of the large opening portion 92a. The insulating film f6 is continuous with the insulating film f4 on the rear surface 22 side. An SiO2 film, a SiN film, or the like is formed as the insulating film f6.

[0032] A distance d1 between the inner boundary and the outer boundary of the second semiconductor region 3 is greater than a distance d2 between the outer boundary of the second semiconductor region 4 and the inner boundary of the third semiconductor region 5 (distance between the inner boundary and the outer boundary of the first partial region 31).

[0033] The inner boundary of the third semiconductor region 5 surrounds the opening of the through-hole 9A on the rear surface 22 side when viewed from the thickness direction of the semiconductor substrate 2. That is, the third semiconductor region 5 is provided in a region further outward than the through-hole 9A when viewed from the thickness direction of the semiconductor substrate 2.

[0034] For example, the thickness / impurity concentration of each region is as follows.

[0035] First semiconductor region 3: Thickness of 50 to 625 µm / impurity concentration of 5 × 10 11 up to 5 × 10 15 cm -3

[0036] Second semiconductor region 4: Thickness of 1.0 to 10 µm / impurity concentration of 1 × 10 18 up to 1 × 10 20 cm -3

[0037] Third semiconductor region 5: Thickness from 0.01 to 3.0 µm / impurity concentration of 1 × 10 18 up to 1 × 10 20 cm -3

[0038] Fourth semiconductor region 6: Thickness of 1.0 to 10 µm / impurity concentration of 1 × 10 18 up to 1 × 10 20 cm -3

[0039] Fifth semiconductor region 7: Thickness from 1.0 to 620 µm / impurity concentration of 1 × 10 18 up to 1 × 10 20 cm -3

[0040] The through-hole electrode 81a is provided within the through-hole opening 9A. The through-hole electrode 81a has a hollow, four-sided frustum shape with a completely open bottom. The through-hole electrode 81a is formed on the inner wall of the small opening portion 91a and on the insulating film f6 within the large opening portion 92a. The through-hole electrode 81a blocks the opening of the through-hole opening 9A on the surface 21 side.

[0041] The contact electrode 82a is formed on the surface 21. The contact electrode 82a electrically connects the third semiconductor region 5 and the breakdown electrode 81a. The contact electrode 82a includes a disc-shaped portion and a circular annular portion. The disc-shaped portion is formed on the insulating film f1. The disc-shaped portion covers the opening of the breakdown opening 9A on the surface 21 side. The disc-shaped portion is coupled to the breakdown electrode 81a. The circular annular portion extends from the outer boundary on a surface of the disc-shaped portion (surface on the side of the insulating film f1) to the radially outer side. The circular annular portion passes through the insulating film f1 and comes into contact with the third semiconductor region 5.

[0042] The outer boundary of the contact electrode 82a surrounds the opening of the through-hole 9A on the rear surface 22 side when viewed from the thickness direction of the semiconductor substrate 2. That is, the contact electrode 82a is provided over the area of ​​the inside and outside of the through-hole 9A when viewed from the thickness direction of the semiconductor substrate 2.

[0043] The terminal electrode 83a is formed on the rear surface 22. The terminal electrode 83a is formed on the insulating film f4. The terminal electrode 83a has an annular shape such that the outer boundary thereof has a circular shape and the inner boundary thereof has a quadrilateral shape. The inner boundary of the terminal electrode 83a is coupled to the breakdown electrode 81a. The contact electrode 82a, the breakdown electrode 81a, and the terminal electrode 83a are formed, for example, of aluminum or the like. [Method for manufacturing a photodiode array]

[0044] Next, an example of a method for manufacturing the photodiode array 1 will be described.

[0045] As in Fig. 4 shows first a carrier material S of an n --type Si with a crystal plane (100) is prepared. The first semiconductor region 3 is enclosed in the carrier material S. Subsequently, the insulating film f1 is formed on the surface 21 by, for example, thermal oxidation.

[0046] As in Fig. As shown in Figure 5, the insulating film f1 is subsequently removed by photoetching at positions where the second semiconductor region 4 and the fourth semiconductor region 6 are formed, and an opening is formed. Phosphorus is thermally diffused into the substrate S through the opening. In this case, phosphorus is also thermally diffused into the back surface 22. This forms the second semiconductor region 4, the fourth semiconductor region 6, and the fifth semiconductor region 7. Subsequently, the opening is closed by thermal oxidation.

[0047] As in Fig. As shown in Figure 6, the insulating film f1 at a position where the third semiconductor region 5 will be formed is subsequently removed by photoetching, and an opening is formed. Boron is thermally diffused into the substrate S through the opening. This forms the third semiconductor region 5. The opening is then closed by thermal oxidation.

[0048] As in Fig. Next, as shown in Figure 7, the insulating film f1 is removed by photoetching at a position where the circular annular portion of the contact electrode 82a will be formed, and an opening (contact opening) is formed. Subsequently, the contact electrode 82a is formed by sputtering.

[0049] As in Fig. As shown in Figure 8, the insulating film f3 is subsequently formed on the insulating film f1 and the contact electrode 82a by, for example, plasma CVD, LP-CVD, or the like. Subsequently, chemical mechanical polishing (CMP) is performed on the surface 21 side (specifically, insulating film f3) to adjust the thickness of a portion through which light passes.

[0050] As in Fig. As shown in Figure 9, anisotropic etching is subsequently performed on the back surface 22 by alkaline etching (using a potassium hydroxide solution, TMAH, hydrazine, EDP, or the like). This forms the large opening portion 92a in which the inner wall thereof and the surface 21 form an angle of approximately 55°. The anisotropic etching is performed until the large opening portion 92a reaches the insulating film f1. Subsequently, the small opening portion 91a is formed by dry etching.

[0051] As in Fig. As shown in Fig. 10, the insulating films f4 and f6 on the rear surface 22, the inner wall of the large opening portion 92a and the inner wall of the small opening portion 91a are formed by, for example, plasma CVD, LP-CVD or the like.

[0052] As in Fig. Subsequently, as shown in Fig. 11, the insulating film f6 on the inner wall of the small opening portion 91a is removed by photoetching to thereby form an opening (contact hole), and a portion of the contact electrode 82a is exposed on the rear surface 22 side. Subsequently, the breakdown electrode 81a and the terminal electrode 83a are formed by sputtering.

[0053] As in Fig. As shown in Figure 12, the insulating film f5 is subsequently formed on the insulating film f4, the terminal electrode 83a, and the breakdown electrode 81a by, for example, plasma CVD, LP-CVD, or the like. Subsequently, the insulating film f5 on the inner boundary side of the terminal electrode 83a and the breakdown electrode 81a is removed by photoetching. As described above, the Fig. 3 shown configuration. [CT device]

[0054] As in Fig. As shown in Figure 13, the CT apparatus 100 includes the aforementioned photodiode array 1, a scintillator 101, and a mounting substrate 102.

[0055] The scintillator 101 comes into contact with the insulating film f3. The scintillator 101 has a rectangular parallelepiped shape. When viewed from the thickness direction of the semiconductor substrate 2, the scintillator 101 has approximately the same size as that of the third semiconductor region 5 forming a light detection region and overlaps with the third semiconductor region 5. The scintillator 101 is a solid-state scintillator such as a crystalline scintillator (a crystalline material such as CsI, NaI, LaBr3, or GAGG), a ceramic scintillator (a sintered body of an inorganic phosphor), or a plastic scintillator (such as PET). A reflective film 103 is provided on surfaces other than the contact surface with the insulating film f3 in the scintillator 101. The reflective film 103 is formed of, for example, aluminum, titanium oxide or the like.

[0056] The mounting substrate 102 includes an electrode 104. The electrode 104 is electrically connected to the breakdown electrode 81a via a bump electrode 105 formed within the breakdown electrode 81a. The bump electrode 105 is formed of a conductive material such as solder, gold, nickel, copper, or a conductive adhesive resin.

[0057] In the CT device 100, when X-rays are incident on the scintillator 101, the scintillator 101 emits scintillation light. The scintillation light is incident directly on the third semiconductor region 5 or is incident on the third semiconductor region 5 after being reflected by the contact electrode 82a, the reflective film 103, and the like. Information of a charge generated in the light detection region by the incidence of the scintillation light is input to the mounting substrate 102 via the contact electrode 82a, the breakdown electrode 81a, the terminal electrode 83a, and the bump electrode 105.

[0058] In the photodiode array 1 of the present embodiment described above, in each of the photodiodes PD1, the through-hole 9A passes through the first semiconductor region 3 and the second semiconductor region 4, and the second semiconductor region 4 is surrounded by the third semiconductor region 5. The third semiconductor region 5, together with the first semiconductor region 3, forms the light detection region. Here, in each photodiode PD1, which is a pixel, the through-hole 9A is surrounded by the light detection region. This reduces the distance between the adjacent photodiodes PD1 and PD1. Thus, it is possible to improve the aperture ratio.

[0059] The second semiconductor region 4, through which the through-hole 9A passes, has a higher impurity concentration than the impurity concentration of the first semiconductor region 3. Therefore, a surface leakage current generated in the inner wall of the through-hole 9A and directed to the light detection region can be reduced by the second semiconductor region 4. In addition, damage caused by etching can be reduced by the second semiconductor region 4. Thus, it is possible to improve electrical characteristics. These effects are more appropriately exhibited by the second semiconductor region 4, which is formed to be deeper than the third semiconductor region 5.

[0060] Since the materials of the insulating film f6 and the semiconductor substrate 2 are different from each other, stress is assumed to occur at the interface between the insulating film f6 and the through hole 9A. In the photodiode array 1, since the second semiconductor region 4 through which the through hole 9A passes has a higher impurity concentration than the impurity concentration of the first semiconductor region 3, the stress occurring at the interface between the through hole 9A and the insulating film f6 can be alleviated by the second semiconductor region 4. Thus, it is possible to improve the strength thereof.

[0061] Since the semiconductor substrate 2 has the surface 21 and the back surface 22 with large areas compared to its thickness, distortion is assumed to occur in the semiconductor substrate 2. In the photodiode array 1, the stress occurring in the through-hole 9A due to distortion of the semiconductor substrate 2 can be reduced by the second semiconductor region 4 through which the through-hole 9A passes. Thus, it is possible to improve its strength.

[0062] When the bump electrode 105 is formed within the through-hole 9A, it is assumed that stress occurs in the through-hole 9A due to thermal contraction of the bump electrode 105 or the like. In the photodiode array 1, stress or the like occurring during the formation of the bump electrode 105 can be alleviated by the second semiconductor region 4 through which the through-hole 9A passes. Thus, it is possible to improve the strength thereof.

[0063] The second semiconductor region 4 and the third semiconductor region 5 are separated from each other. The first partial region 31, which is a partial region of the first semiconductor region 3, is provided between the second semiconductor region 4 and the third semiconductor region 5 so as to surround the second semiconductor region 4. Therefore, it is possible to prevent short-circuiting between the second semiconductor region 4 and the third semiconductor region 5. This makes it possible to improve electrical properties.

[0064] The distance d 1 between the inner boundary and the outer boundary of the second semiconductor region 4 is greater than the distance d 2 between the outer boundary of the second semiconductor region 4 and the inner boundary of the third semiconductor region 5. Therefore, a plurality of stresses occurring in the through-hole 9A described above can be much better mitigated by the second semiconductor region 4.

[0065] The inner boundary of the third semiconductor region 5 surrounds the opening of the through hole 9A on the rear surface 22 side when viewed from the thickness direction of the semiconductor substrate 2. That is, the third semiconductor region 5 is provided in a region further outward than the through hole 9A when viewed from the thickness direction of the semiconductor substrate 2. Therefore, by forming the bump electrode 105 inside the through hole 9A, or the like, it is possible to reduce stress applied to the third semiconductor region 5 constituting the light detection region.

[0066] Each of the photodiodes PD1 includes the contact electrode 82a formed on the surface 21 and connecting the third semiconductor region 5 and the through-hole electrode 81a. The outer boundary of the contact electrode 82a surrounds the opening of the through-hole 9A on the rear surface side when viewed from the thickness direction of the semiconductor substrate 2. That is, when viewed from the thickness direction of the semiconductor substrate 2, the contact electrode 82a is provided over the area of ​​the inside and outside of the through-hole 9A. Therefore, it is possible to improve the strength in the vicinity of the through-hole 9A.

[0067] The opening of the through hole 9A on the surface 21 side has a circular shape. Therefore, if the bump electrode 105 is formed within the through hole 9A or the like, it is possible to prevent stress concentration from occurring in the through hole 9A.

[0068] When the through-hole is surrounded by the light detection region, leakage current generated due to damage to the inner wall of the through-hole tends to enter the light detection region. Therefore, when the through-hole is surrounded by the light detection region, it is preferable to reduce damage to the inner wall of the through-hole. In the photodiode array 1, the through-hole 9A includes the opening portion 92a with a tapered shape extending from the surface 21 to the rear surface 22. The large opening portion 92a is formed by anisotropic etching. With the anisotropic etching, damage to the inner wall of the through-hole 9A is unlikely to occur. Therefore, in the photodiode array 1, it is possible to reduce leakage current from the through-hole 9A. Therefore, it is possible to improve electrical characteristics.

[0069] The inner wall of the large opening portion 92a and the rear surface 22 form an obtuse angle (approximately 125°). Therefore, when the insulating films f4 and f6 are formed, the insulating films f4 and f6 at the opening boundary of the through-hole 9A on the rear surface 22 side tend to be thicker than when the inner wall of the large opening portion 92a and the rear surface 22 form a right angle or an acute angle. Therefore, it is possible to improve electrical characteristics.

[0070] The outer boundary of the second semiconductor region 4 has a circular shape. Therefore, it is possible to prevent the concentration of an electric field compared to the case where the outer boundary of the second semiconductor region 4 has a polygonal shape or the like.

[0071] Next, a photodiode array of another embodiment will be described.

[0072] As in Fig. 14, the photodiode array of the present embodiment includes a photodiode PD2 instead of the previously mentioned photodiode PD1 (see Fig. 3). The photodiode PD2 differs from the photodiode PD1 in that the shapes of a breakdown opening, a breakdown electrode, and a terminal electrode in the photodiode PD2 are different from those in the photodiode PD1.

[0073] A through-hole 9B includes a small opening portion 91b located on the surface 21 side and a large opening portion 92b located on the rear surface 22 side. The small opening portion 92b has the same configuration as that of the aforementioned small opening portion 91a.

[0074] The large opening portion 92b passes through the first semiconductor region 3 and the second semiconductor region 4. The large opening portion 92b has a cylindrical shape with a diameter larger than the diameter of the small opening portion 91b. An opening of the through-hole 9B on the rear surface 22 side has a circular shape. The opening portion 91b and the opening portion 92b are arranged coaxially with each other. The large opening portion 92b can be formed by using dry etching instead of anisotropic etching, for example, in the aforementioned manufacturing method.

[0075] The inner boundary of the third semiconductor region 5 surrounds the opening of the through-hole 9B on the rear surface 22 side when viewed from the thickness direction of the semiconductor substrate 2. That is, the third semiconductor region 5 is provided in a region located further outward than the through-hole 9B when viewed from the thickness direction of the semiconductor substrate 2.

[0076] The outer boundary of the contact electrode 82a surrounds the opening of the through-hole 9B on the rear surface 22 side when viewed from the thickness direction of the semiconductor substrate 2. That is, the electrode 82 is provided over the area of ​​the inside and outside of the through-hole 9B when viewed from the thickness direction of the semiconductor substrate 2.

[0077] A through-hole electrode 81b is provided within the through-hole opening 9B. The through-hole electrode 81b has a cylindrical shape with one end closed on the surface 21 side. The through-hole electrode 81b is formed on the inner wall of the small opening portion 91b and the insulating film f6 within the large opening portion 92b. The through-hole electrode 81b blocks the opening of the through-hole opening 9B on the surface 21 side.

[0078] A terminal electrode 83b is formed on the rear surface 22. The terminal electrode 83b is formed on the insulating film f4. The terminal electrode 83b has a circular annular shape. The inner boundary of the terminal electrode 83b is coupled to the breakdown electrode 81b.

[0079] In the photodiode array comprising a plurality of photodiodes PD2 described above, the through-hole opening 9B in each of the photodiodes PD2 passes through the first semiconductor region 3 and the second semiconductor region 4, and the second semiconductor region 4 is surrounded by the third semiconductor region 5. The third semiconductor region 5, together with the first semiconductor region 3, forms a light detection region. Here, in each photodiode PD2, which is a pixel, the through-hole opening 9B is surrounded by the light detection region. This reduces the distance between the adjacent photodiodes PD2 and PD2. Thus, it is possible to improve the aperture ratio.

[0080] The second semiconductor region 4, through which the through-hole 9B passes, has a higher impurity concentration than the impurity concentration of the first semiconductor region 3. Therefore, a surface leakage current generated in the inner wall of the through-hole 9B and directed to the light detection region can be reduced by the second semiconductor region 4. In addition, damage caused by etching can be reduced by the second semiconductor region 4. Thus, it is possible to improve electrical characteristics. These effects are more appropriately exhibited by the second semiconductor region 4, which is formed to be deeper than the third semiconductor region 5.

[0081] Since the materials of the insulating film f6 and the semiconductor substrate 2 are different from each other, stress is assumed to occur at the interface between the insulating film f6 and the through hole 9B. In the photodiode array 1, since the second semiconductor region 4 through which the through hole 9B passes has a higher impurity concentration than the impurity concentration of the first semiconductor region 3, the stress occurring at the interface between the through hole 9B and the insulating film f6 can be alleviated by the second semiconductor region 4. Thus, it is possible to improve its strength.

[0082] Since the semiconductor substrate 2 has the surface 21 and the back surface 22 with large areas compared to their thickness, distortion is assumed to occur in the semiconductor substrate 2. In the photodiode array 1, the stresses occurring in the through-hole 9B due to distortion of the semiconductor substrate 2 can be mitigated by the second semiconductor region through which the through-hole 9B passes. Thus, it is possible to improve its strength.

[0083] When the bump electrode 105 is formed within the through-hole 9B, it is assumed that stress occurs in the through-hole 9B due to thermal contraction of the bump electrode 105 or the like. In the photodiode array 1, stress occurring during the formation of the bump electrode 105 or the like can be alleviated by the second semiconductor region 4 through which the through-hole 9B passes. Thus, it is possible to improve the strength thereof.

[0084] The second semiconductor region 4 and the third semiconductor region 5 are separated from each other. The first partial region 31, which is a partial region of the first semiconductor region 3, is provided between the second semiconductor region 4 and the third semiconductor region 5 so as to surround the second semiconductor region 4. Therefore, it is possible to prevent short-circuiting between the second semiconductor region 4 and the third semiconductor region 5. This makes it possible to improve electrical properties.

[0085] The distance d 1 between the inner boundary and the outer boundary of the second semiconductor region 4 is greater than the distance d 2 between the outer boundary of the second semiconductor region 4 and the inner boundary of the third semiconductor region 5. Therefore, a plurality of stresses occurring in the through-hole 9B described above can be much better mitigated by the second semiconductor region.

[0086] The inner boundary of the third semiconductor region 5 surrounds the opening of the through hole 9B on the rear surface 22 side when viewed from the thickness direction of the semiconductor substrate 2. That is, the third semiconductor region 5 is provided in a region farther outward than the through hole 9B when viewed from the thickness direction of the semiconductor substrate 2. Therefore, by forming the bump electrode within the through hole 9B or the like, it is possible to reduce stress applied to the third semiconductor region 5 constituting the light detection region.

[0087] Each of the photodiodes PD2 includes the contact electrode 82a formed on the surface 21 and connecting the third semiconductor region 5, and the through-hole electrode 81b. The outer boundary of the contact electrode 82a surrounds the opening of the through-hole 9B on the rear surface side when viewed from the thickness direction of the semiconductor substrate 2. That is, when viewed from the thickness direction of the semiconductor substrate 2, the contact electrode 82a is provided over the area of ​​the inside and outside of the through-hole 9B. Therefore, it is possible to improve the strength in the vicinity of the through-hole 9B.

[0088] The opening of the through-hole 9B on the surface 21 side has a circular shape. Therefore, for example, when the bump electrode is formed within the through-hole 9B or the like, it is possible to prevent the occurrence of stress concentration in the through-hole 9B. Furthermore, the opening of the through-hole 9B on the rear surface 22 side has a circular shape. Therefore, it is possible to further prevent the occurrence of stress concentration in the through-hole 9B.

[0089] The second semiconductor region has a circular annular shape. Therefore, it is possible to prevent the concentration of an electric field compared to the case where the second semiconductor region has a polygonal shape or the like.

[0090] Next, a photodiode array of a further different embodiment will be described.

[0091] As in Fig. 15, the photodiode array of the present embodiment includes a photodiode PD 3 instead of the previously mentioned photodiode PD 1 (see Fig. 2). The photodiode PD 3 differs from the photodiode 1 in that the light detection area is divided into a plurality of (four) parts.

[0092] Specifically, the photodiode PD 3 includes a plurality of (four) third semiconductor regions 51 having a shape different from that of the third semiconductor region 5, instead of the third semiconductor region 5. The photodiode PD 3 includes a plurality of (four) third subregions 33, which are a subregion of the first semiconductor region 3, instead of the first and second subregions 31 and 32. The photodiode PD 3 includes a plurality of sixth semiconductor regions 10.

[0093] The plurality of third semiconductor regions 51 are provided so as to be separated from one another. The plurality of third semiconductor regions 51 surround the second semiconductor region 4 when viewed from the thickness direction of the semiconductor substrate 2. Each of the third semiconductor regions 51 is separated from the second semiconductor region 4. Each of the third semiconductor regions 51 has a shape such as a corner notched in a fan-like shape from a rectangle when viewed from the thickness direction of the semiconductor substrate 2.

[0094] The distance d 1 between the inner boundary and the outer boundary of the second semiconductor region 4 is greater than a distance d 3 between the outer boundary of the second semiconductor region 4 and the inner boundary of the third semiconductor region 51 (distance between the inner boundary and the outer boundary in each of the third subregions 33).

[0095] The inner boundaries of the plurality of third semiconductor regions 51 surround the opening of the through-hole 9A on the rear surface 22 side when viewed from the thickness direction of the semiconductor substrate 2. That is, the plurality of third semiconductor regions 51 are provided further outward than the through-hole 9A when viewed from the thickness direction of the semiconductor substrate 2.

[0096] Each of the third semiconductor regions 51 is connected to the contact electrode 82a. Information received in the plurality of third semiconductor regions 51 is output as a piece of information from the breakdown electrode 81b. That is, the photodiode PD3 comprising the plurality of third semiconductor regions 51 functions as a pixel.

[0097] Each of the third subregions 33 has an annular shape. Each of the third subregions 33 surrounds the third semiconductor region 51 when viewed from the thickness direction of the semiconductor substrate 2. The plurality of third subregions 33 are provided such that they are separated from one another. The plurality of third subregions 33 surround the second semiconductor region 4 when viewed from the thickness direction of the semiconductor substrate 2.

[0098] The sixth semiconductor regions 10 are provided with respect to the first semiconductor region 3 on the side of the surface 21 of the semiconductor substrate 2. Each of the sixth semiconductor regions 10 is formed between the adjacent third partial regions 33 and 33 when viewed from the thickness direction of the semiconductor substrate 2. The sixth semiconductor region 10 has an approximately quadrilateral shape when viewed from the thickness direction of the semiconductor substrate 2. The sixth semiconductor region 10 is an n + -type semiconductor region and has a higher impurity concentration than the impurity concentration of the first semiconductor region 3. The sixth semiconductor region 10 is continuous with the second semiconductor region 4 and the fourth semiconductor region 6, which n +-type semiconductor regions are provided. The sixth semiconductor region 10 has, for example, approximately the same thickness and impurity concentration as those of the second semiconductor region 4 and the fourth semiconductor region 6. The second semiconductor region 4 is formed, for example, by diffusing an n-type impurity or the like. The second semiconductor region 4 is formed, for example, simultaneously with the second semiconductor region 4 and the fourth semiconductor region 6 in the aforementioned manufacturing process.

[0099] The photodiode array comprising a plurality of photodiodes PD3 described above has the same effects as that in the aforementioned photodiode array 1. Specifically, the through-hole opening 9A passes through the first semiconductor region 3 and the second semiconductor region 4, and the second semiconductor region 4 is surrounded by the plurality of third semiconductor regions 51. The plurality of third semiconductor regions 51, together with the first semiconductor region 3, form the light detection region. Here, in each photodiode PD3, which is a pixel, the through-hole opening 9A is surrounded by the light detection region. This reduces the distance between adjacent photodiodes PD3 and PD3. Thus, it is possible to improve an aperture ratio.

[0100] In the photodiode PD3, the second semiconductor region 4 is formed continuously with the fourth semiconductor region 6, which is grounded, via the sixth semiconductor region 10. Therefore, in the photodiode PD3, it is possible to improve electrical stability compared to the aforementioned photodiode PD1.

[0101] Next, a photodiode array of another embodiment will be described.

[0102] As in Fig. As shown in Fig. 16, in the photodiode PD 4 in the photodiode array of the present embodiment, the number of divisions of the light detection area is different from that in the aforementioned photodiode PD 3 (see Fig. 15).

[0103] Specifically, the photodiode PD4 includes a plurality of (eight) third semiconductor regions 52 instead of the plurality of (four) third semiconductor regions 51. The third semiconductor region 52 has an approximately quadrilateral shape when viewed from the thickness direction of the semiconductor substrate 2. The photodiode PD4 includes a plurality of (eight) third subregions 34 instead of the plurality of (four) third subregions 33. The third subregion 34 has an approximately quadrilateral annular shape when viewed from the thickness direction of the semiconductor substrate 2. The photodiode PD4 includes a plurality of (eight) sixth semiconductor regions 11 instead of the plurality of (four) sixth semiconductor regions 10. The sixth semiconductor region 11 has an approximately quadrilateral shape when viewed from the thickness direction of the semiconductor substrate 2.

[0104] The photodiode array comprising a plurality of such photodiodes PD 4 has the same effects as the photodiode array comprising the plurality of photodiodes PD 3 described above.

[0105] As described above, the embodiments of the present invention have been described, but the invention is not limited to the embodiments. For example, when the light detection area is divided, the number of divisions can be changed to various numbers without being limited to four or eight. In addition, the material and shape of each configuration of the photodiode array can be changed to various materials and shapes without being limited to the aforementioned materials and shapes.

[0106] Each p-type and n-type conductivity type in the photodiode array can be reversed with respect to the aforementioned types. The photodiode array can be photodiodes arranged one-dimensionally, without being limited to the photodiodes PD 1 to PD 4, which are arranged two-dimensionally. The photodiode array can be applied to various devices, without being limited to the CT device. Industrial applicability

[0107] According to the present invention, it is possible to provide a photodiode array capable of improving an aperture ratio and reliability. List of reference symbols

[0108] 1: Photodiode array, 2: Semiconductor substrate, 3: First semiconductor region, 4: Second semiconductor region, 5: Third semiconductor region, 9A, 9B: Breakthrough opening, 81a, 81b: Breakthrough electrode, 82a: Contact electrode, PD1 to PD4: Photodiode

Claims

[1] A photodiode array (1) comprising a plurality of photodiodes (PD1, PD2, PD3, PD4) formed in a semiconductor substrate (2), each of the photodiodes (PD1, PD2, PD3, PD4) comprising: a first semiconductor region (3) of a first conductivity type, and which is provided in the semiconductor carrier material (2); a second semiconductor region (4) of the first conductivity type, which is provided with respect to the first semiconductor region (3) on a surface side (21) of the semiconductor substrate (2) and has a higher impurity concentration than an impurity concentration of the first semiconductor region (3); at least one third semiconductor region (5) of a second conductivity type, which is provided with respect to the first semiconductor region (3) on the one surface side (21) such that it surrounds the second semiconductor region (4) separately from the second semiconductor region (4) and forms a light detection region together with the first semiconductor region (3); and a breakthrough electrode (81a, 81b) which is provided with a breakthrough opening (9A, 9B) which passes through one surface (21) and the other surface (22) of the semiconductor carrier material (2) so that it passes through the first semiconductor region (3) and the second semiconductor region (4), and is electrically connected to the at least one third semiconductor region (5), and wherein the second semiconductor region (4) is surrounded by the at least one third semiconductor region (5) which is electrically connected to the breakdown electrode (81a, 81b) provided in the same breakdown opening (9A, 9B) passing through the second semiconductor region (4). [2] The photodiode array (1) according to claim 1, wherein a portion of the first semiconductor region is provided between the second semiconductor region and the third semiconductor region so as to surround the second semiconductor region. [3] The photodiode array (1) according to claim 1 or 2, wherein a distance between an inner boundary and an outer boundary of the second semiconductor region is greater than a distance between the outer boundary of the second semiconductor region and an inner boundary of the third semiconductor region. [4] The photodiode array (1) according to any one of claims 1 to 3, wherein the inner boundary of the third semiconductor region surrounds an opening of the through hole on the other surface side when viewed from a thickness direction of the semiconductor substrate. [5] The photodiode array (1) according to any one of claims 1 to 4, wherein each of the photodiodes comprises a contact electrode formed on one surface and electrically connecting the third semiconductor region and the breakdown electrode, and an outer boundary of the contact electrode surrounds the opening of the breakdown opening on the other surface side when viewed from the thickness direction of the semiconductor substrate. [6] The photodiode array (1) according to any one of claims 1 to 5, wherein the opening of the through hole on the one surface side has a circular shape.

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