Photoelectric conversion device

Abstract

A transfer section of a photoelectric conversion device of the present application has a first transfer region that transfers charges along a first line, a second transfer region that transfers charges along a second line, a third transfer region that transfers charges along a third line, a first transfer electrode, and a second transfer electrode. The third line is offset from the line of at least one of the first line and the second line. The third transfer region includes a first semiconductor region having a first impurity concentration and a second semiconductor region having a second impurity concentration higher than the first impurity concentration. The second semiconductor region extends along the third line in a manner that widens on the second transfer region side. The first semiconductor region is disposed on both sides of the second semiconductor region.

Description

Technical Field

[0001] This disclosure relates to a photoelectric conversion device. Background Technology

[0002] As an existing photoelectric conversion device, Patent Document 1 describes a solid-state imaging element as follows. Specifically, the solid-state imaging element described in Patent Document 1 includes: an imaging region that generates charge based on incident light; and a transmission unit (specifically, a vertical shift register, a horizontal shift register, an angle register, and a multiplier register) that transmits the charge generated in the imaging region. In the solid-state imaging element described in Patent Document 1, the horizontal shift register, the angle register, and the multiplier register extend in a curved manner within the angle register.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2010-177588 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In the solid-state imaging element described in Patent Document 1, the corner register has multiple transfer electrodes. Here, if the number of transfer electrodes in the corner register is reduced, the difference between the inner and outer widths of each transfer electrode becomes larger, raising concerns about insufficient charge transfer on the outer side of each transfer electrode. To avoid this, increasing the number of transfer electrodes in the corner register leads to the following problems: Firstly, since the inner width of each transfer electrode becomes smaller, there are concerns about increased structural complexity and decreased yield. Secondly, if the corner register has a large number of transfer electrodes, there are concerns about hindering high-speed operation or increasing power consumption due to the increased capacitance.

[0008] The purpose of this disclosure is to provide a photoelectric conversion device that can reliably transmit charge without increasing the number of transmission electrodes, even when the direction of charge transmission in the transmission section is changed.

[0009] Technical means for solving problems

[0010] One aspect of the photoelectric conversion device disclosed herein may also include: a photoelectric conversion unit that generates charge based on incident light; and a transmission unit that transmits charge, the transmission unit having: a first transmission region that transmits charge along a first line; a second transmission region that transmits charge along a second line; a third transmission region that transmits charge from the first transmission region side to the second transmission region side along a third line connected to the first and second lines; a first transmission electrode disposed on the first transmission region; and a second transmission electrode disposed on the second transmission region; the third line being offset from at least one of the first and second lines, the third transmission region comprising: a first semiconductor region having a first impurity concentration; and a second semiconductor region having a second impurity concentration higher than the first impurity concentration, the second semiconductor region extending along the third line in a manner that widens on the second transmission region side, the first semiconductor region being disposed on both sides of the second semiconductor region in the direction of widening of the second semiconductor region.

[0011] In a photoelectric conversion device according to one aspect of this disclosure, the transfer section includes: a first transfer region that transfers charge along a first line; a second transfer region that transfers charge along a second line; and a third transfer region that transfers charge from the first transfer region side to the second transfer region side along a third line connected to the first and second lines, wherein the third line is offset from at least one of the first and second lines. Accordingly, the direction of charge transfer, etc., is changed in at least the third transfer region. In the third transfer region, a second semiconductor region having a second impurity concentration higher than the first impurity concentration extends along the third line in a manner that widens towards the second transfer region side, and the first semiconductor region having the first impurity concentration is disposed on both sides of the second semiconductor region in the direction of widening of the second semiconductor region. Accordingly, a potential gradient (potential tilt) is formed in the third transfer region where charge moves along the third line from the first transfer region side to the second transfer region side. Therefore, it is unnecessary to arrange more transfer electrodes in the third transfer region to change the direction of charge transfer, etc. Therefore, according to one aspect of the photoelectric conversion device of this disclosure, even if the direction of charge transmission in the transmission section is changed, the number of transmission electrodes can be avoided and the charge can be reliably transmitted.

[0012] In one aspect of the photoelectric conversion device disclosed herein, the direction in which the second transmission region transmits charge along the second line may differ from the direction in which the first transmission region transmits charge along the first line. Accordingly, the direction of charge transmission can be changed within the transmission section.

[0013] In the photoelectric conversion device of this disclosure, the third line may also be a curve. Accordingly, the direction of charge transmission can be smoothly changed in the transmission section.

[0014] In one aspect of the photoelectric conversion device disclosed herein, the transmission unit may also have a third transmission electrode disposed on the third transmission region. Accordingly, not only the potentials of the first and second transmission regions can be controlled, but also the potential of the third transmission region can be controlled, thus enabling more reliable charge transmission.

[0015] In one aspect of the photoelectric conversion device disclosed herein, the transmission unit may further include a buried layer having a conductivity type different from that of the first semiconductor region and the second semiconductor region, and the buried layer is disposed on the third transmission region. Accordingly, it is unnecessary to arrange transmission electrodes on the third transmission region, thus simplifying the structure. Furthermore, the generation of dark current in the third transmission region can be suppressed.

[0016] One aspect of the photoelectric conversion device disclosed herein may also include a light-shielding layer disposed on the light incident side relative to the transmission unit. This prevents the generation of unwanted charges in the transmission unit due to light incident on it.

[0017] The effects of the invention

[0018] According to this disclosure, a photoelectric conversion device can be provided that can reliably transmit charge without increasing the number of transmission electrodes, even when the direction of charge transmission in the transmission section is changed, such as by altering the direction of charge transmission. Attached Figure Description

[0019] Figure 1 This is a top view of one embodiment of a photoelectric conversion device.

[0020] Figure 2 It is along Figure 1 The cross-sectional view of the photoelectric conversion device of line II-II is shown.

[0021] Figure 3 yes Figure 1 The top view of the conveyor unit shown.

[0022] Figure 4 It is along Figure 3 The cross-sectional view of the transmission section of line IV-IV is shown.

[0023] Figure 5 It is along Figure 3 The diagram shows a cross-sectional view of the transmission section of the VV line.

[0024] Figure 6 It is used to explain Figure 3 The diagram shows the principle of the formation of a potential gradient in the third transmission region.

[0025] Figure 7 yes Figure 3 The potential diagram of the transmission section is shown.

[0026] Figure 8 yes Figure 3 The potential diagram of the transmission section is shown.

[0027] Figure 9 yes Figure 3 The potential diagram of the transmission section is shown.

[0028] Figure 10 This is a cross-sectional view of a modified photoelectric conversion device.

[0029] Figure 11 yes Figure 10 The cross-sectional view of the conveyor section is shown.

[0030] Figure 12 This is a top view of the transmission section in a modified example.

[0031] Figure 13 It is along Figure 12 The cross-sectional view of the transmission section of line XIII-XIII is shown.

[0032] Figure 14 It is along Figure 12 The cross-sectional view of the transmission section of the XIV-XIV line is shown.

[0033] Figure 15 This is a top view of the transmission section in a modified example.

[0034] Figure 16 This is a top view of the transmission section in a modified example.

[0035] Figure 17 This is a top view of the transmission section in a modified example.

[0036] Figure 18 This is a top view of the transmission section in a modified example.

[0037] Figure 19 This is a top view of the transmission section in a modified example.

[0038] Figure 20 yes Figure 12 The potential diagram of the transmission section is shown.

[0039] Figure 21 yes Figure 12 The potential diagram of the transmission section is shown.

[0040] Figure 22 yes Figure 12 The potential diagram of the transmission section is shown. Detailed Implementation

[0041] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, the same or equivalent parts are given the same reference numerals in the drawings, and repeated descriptions are omitted.

[0042] [Structure of photoelectric conversion device]

[0043] like Figure 1 and Figure 2 As shown, the photoelectric conversion device 1 includes a semiconductor layer 2 and a wiring layer 3. In the semiconductor layer 2, a photoelectric conversion unit 4 is provided that generates charge based on the incident light hν. In the semiconductor layer 2 and the wiring layer 3, a charge transfer unit 5 is provided, including a vertical shift register 5a, a horizontal shift register 5b, an angle register 5c, and a multiplication register 5d. The photoelectric conversion device 1 is, for example, a back-illuminated solid-state imaging device whose CCD-type imaging area is composed of the photoelectric conversion unit 4 and the vertical shift register 5a. Hereinafter, the thickness direction of the semiconductor layer 2 will be referred to as the Z-axis direction, the direction perpendicular to the Z-axis direction will be referred to as the X-axis direction, and the direction perpendicular to both the Z-axis and X-axis directions will be referred to as the Y-axis direction.

[0044] Semiconductor layer 2 includes: a semiconductor substrate 21, a semiconductor layer 22, and a semiconductor region 23. The semiconductor substrate 21 is, for example, a P-type semiconductor substrate. + A silicon substrate. The semiconductor layer 22 is, for example, a P-type semiconductor layer formed on the surface 21a of the semiconductor substrate 21 by epitaxial growth. - A type silicon layer. Semiconductor region 23 is formed, for example, within semiconductor layer 22 by doping with N-type impurities along the surface 22a of semiconductor layer 22. + Type semiconductor region.

[0045] In addition, the so-called "P" + "Type", for example, refers to a concentration of 1×10⁻⁶ for a type P impurity. 17 cm -3 The above describes the situation where the concentration of P-type impurities is high, the so-called "P - "Type", for example, refers to a concentration of 1×10⁻⁶ for a type P impurity. 15 cm -3 The following describes the case where the concentration of P-type impurities is low. The same applies to N-type impurities.

[0046] A recess 24 is formed on the back surface 21b of the semiconductor substrate 21. The recess 24 is formed, for example, by etching, and is a frustum-shaped quadrangular pyramid extending to the side opposite to the surface 21a of the semiconductor substrate 21. In the photoelectric conversion device 1, the PN junction region formed in the semiconductor layer 22 corresponding to the bottom surface 24a of the recess 24 constitutes the photoelectric conversion section 4.

[0047] A light-shielding layer 6 is formed on the back surface 21b of the semiconductor substrate 21 and the side surface 24b of the recess 24. The light-shielding layer 6 has an opening 6a corresponding to the bottom surface 24a of the recess 24. The light-shielding layer 6 is, for example, a metal film formed on the back surface 21b and the side surface 24b by vapor deposition or sputtering. In the photoelectric conversion device 1, light hν is incident from the back surface 21b of the semiconductor substrate 21 through the opening 6a of the light-shielding layer 6 and the bottom surface 24a of the recess 24 onto the photoelectric conversion unit 4.

[0048] A wiring layer 3 is formed on the surface 22a of the semiconductor layer 22, separated by an insulating film 7. The wiring layer 3 has multiple transmission electrodes (not shown) and an interlayer insulating film 31. The insulating film 7 is, for example, a SiO2 film. The interlayer insulating film 31 is, for example, a BPSG film.

[0049] The vertical shift register 5a has multiple transfer electrodes disposed in the wiring layer 3 corresponding to the portion of the photoelectric conversion unit 4. The vertical shift register 5a transfers the charge generated in the photoelectric conversion unit 4 to one side in the Y-axis direction.

[0050] The horizontal shift register 5b extends along the X-axis direction from one side of the vertical shift register 5a in the Y-axis direction. The horizontal shift register 5b has multiple transfer electrodes arranged in the X-axis direction. The horizontal shift register 5b transfers the charge transferred by the vertical shift register 5a to one side in the X-axis direction (…). Figure 1 (Transmit from the left side of the middle).

[0051] Angle register 5c is positioned to one side of horizontal shift register 5b in the X-axis direction. Angle register 5c transfers the charge transferred by horizontal shift register 5b while simultaneously transferring the charge from one side in the X-axis direction. Figure 1 (left side) to the other side ( Figure 1 (The right side of the text) is changed.

[0052] The multiplier register 5d extends along the X-axis from one side of the horizontal shift register 5b in the Y-axis direction. The multiplier register 5d has multiple transfer electrodes arranged in the X-axis direction. One side of the multiplier register 5d transfers the charge transferred by the angle register 5c to the other side in the X-axis direction. Figure 1 The charge (electrons) is transferred from the right side of the multiplier register 5d, while multiplying the charge (electrons). The charge transferred by the multiplier register 5d is output to the outside via an amplifier formed in the semiconductor layer 22.

[0053] Furthermore, when viewed from the incident side of light hν, the horizontal shift register 5b, the corner register 5c, and the multiplier register 5d are covered by the frame portion surrounding the recess 24 in the semiconductor substrate 21 and the light-shielding layer 6. That is, in the photoelectric conversion device 1, the frame portion of the semiconductor substrate 21 and the light-shielding layer 6 are arranged on the incident side of light hν relative to the horizontal shift register 5b, the corner register 5c, and the multiplier register 5d.

[0054] [Structure of the transport unit]

[0055] For the structure of the part of the transmission unit 5 that corresponds to the corner register 5c, refer to Figure 3 , Figure 4 and Figure 5 A detailed explanation will be provided. Figure 3 yes Figure 1 The top view of the transmission unit 5 shown (specifically, the part of the transmission unit 5 that corresponds to the corner register 5c). Figure 4 It is along Figure 3 The cross-sectional view of the transmission section 5 of line IV-IV shown is shown. Figure 5 It is along Figure 3 The cross-sectional view of the transmission section 5 of the VV line is shown.

[0056] like Figure 3 , Figure 4 and Figure 5 As shown, the transmission unit 5 includes: a first transmission region 51, a second transmission region 52, a third transmission region 53, a first transmission electrode 55, a second transmission electrode 56, and a third transmission electrode 57. The first transmission region 51, the second transmission region 52, and the third transmission region 53 are formed within the semiconductor layer 22. The first transmission electrode 55, the second transmission electrode 56, and the third transmission electrode 57 are disposed within the wiring layer 3.

[0057] The first transmission area 51 and the first transmission electrode 55 correspond to the horizontal shift register 5b (see reference). Figure 1 The downstream end (downstream side in the charge transfer direction) of the second transfer region 52 and the second transfer electrode 56 correspond to the multiplier register 5d (see reference). Figure 1 The end of the upstream side (upstream side in the direction of charge transfer). The third transfer region 53 and the third transfer electrode 57 correspond to the angle register 5c.

[0058] The first transmission region 51 includes a semiconductor region 25 formed on one side of the semiconductor layer 22 in the Z-axis direction (the side in the Z-axis direction opposite to the incident side of light hν). The second transmission region 52 includes a semiconductor region 26 formed on one side of the semiconductor layer 22 in the Z-axis direction. The semiconductor regions 25 and 26 are, for example, N-type impurities formed within the semiconductor layer 22 through doping. +Type semiconductor region.

[0059] The third transfer region 53 includes a first semiconductor region 27 and a second semiconductor region 28 formed on one side of the semiconductor layer 22 in the Z-axis direction. The first semiconductor region 27 has a first impurity concentration. The second semiconductor region 28 has a second impurity concentration that is higher than the first impurity concentration. The first semiconductor region 27 is formed, for example, within the semiconductor layer 22 by doping with an N-type impurity. - The second semiconductor region 28 is, for example, an N-type semiconductor region formed within the semiconductor layer 22 by doping with N-type impurities.

[0060] The upstream ends of the first semiconductor region 27 and the second semiconductor region 28 in the third transmission region 53 are connected to the downstream ends of the semiconductor region 25 in the first transmission region 51. The downstream ends of the first semiconductor region 27 and the second semiconductor region 28 in the third transmission region 53 are connected to the upstream ends of the semiconductor region 26 in the second transmission region 52. Furthermore, in the transmission section 5, around the semiconductor regions 25 and 26 and the first semiconductor region 27 and the second semiconductor region 28, a region similar to P is formed. + The concentration of P-type impurities is higher than that of P-type impurities. ++ Type semiconductor region 29.

[0061] The first transfer electrode 55 is disposed on one side of the first transfer region 51 in the Z-axis direction. That is, the first transfer electrode 55 is disposed on the first transfer region 51. The second transfer electrode 56 is disposed on one side of the second transfer region 52 in the Z-axis direction. That is, the second transfer electrode 56 is disposed on the second transfer region 52. The third transfer electrode 57 is disposed on one side of the third transfer region 53 in the Z-axis direction. That is, the third transfer electrode 57 is disposed on the third transfer region 53. The first transfer electrode 55, the second transfer electrode 56, and the third transfer electrode 57 are electrically separated by an interlayer insulating film 31. The first transfer electrode 55, the second transfer electrode 56, and the third transfer electrode 57 are, for example, formed of polycrystalline silicon.

[0062] like Figure 3 As shown, the first transmission area 51 is located along the first line L1 on one side in the X-axis direction ( Figure 3 The left side of the middle section) transfers charge. Line 1 L1 is a straight line extending in the X-axis direction. The second transfer region 52 extends along line 2 L2 to the other side in the X-axis direction ( Figure 3The second transmission region 52 transmits charge along the right side of the line L2. The second line L2 is a straight line extending in the X-axis direction. The direction in which the second transmission region 52 transmits charge along the second line L2 is different from the direction in which the first transmission region 51 transmits charge along the first line L1. In the photoelectric conversion device 1, the direction in which the second transmission region 52 transmits charge along the second line L2 forms a 180-degree angle with the direction in which the first transmission region 51 transmits charge along the first line L1.

[0063] Line 3 L3 is offset from both line 1 L1 and line 2 L2. That is, line 3 L3 is offset from line 1 L1 and also from line 2 L2. Here, "line 3 L3 is offset from line 1 L1" means that at least a portion of line 3 L3 is not located on the extension of line 1 L1 extending downstream from its downstream end (or, when line 1 L1 is a curve, on the tangent line extending downstream from its downstream end). Similarly, "line 3 L3 is offset from line 2 L2" means that at least a portion of line 3 L3 is not located on the extension of line 2 L2 extending upstream from its upstream end (or, when line 2 L2 is a curve, on the tangent line extending upstream from its upstream end). In the photoelectric conversion device 1, the entire third line L3 is not located on the extension line of the first line L1 extending from the downstream end of the first line L1, and the entire third line L3 is not located on the extension line of the second line L2 extending from the upstream end of the second line L2.

[0064] The second line L2 is offset from the first line L1. Here, "the second line L2 is offset from the first line L1" means that at least a portion of the second line L2 is not located on the extension line of the first line L1 extending from its downstream end (or, when the first line L1 is a curve, on the tangent line extending from its downstream end). In the photoelectric conversion device 1, the entire second line L2 is not located on the extension line of the first line L1 extending from its downstream end.

[0065] The third transmission region 53 transmits charge from the first transmission region 51 to the second transmission region 52 along the third line L3, which connects to the first line L1 and the second line L2. That is, the third transmission region 53 transmits charge from one side along the X-axis direction. Figure 3 (left side) to the other side ( Figure 3 (The right side of the text is changed.) The third line L3 is a curve (e.g., an arc-shaped curve) that connects to the first line L1 and the second line L2. In the photoelectric conversion device 1, the first line L1 and the third line L3 are connected to each other, and the second line L2 and the third line L3 are connected to each other.

[0066] The structure of the third transmission area 53 will be described in more detail. For example... Figure 3As shown, the second semiconductor region 28 extends along the third line L3 in a manner that widens on the side of the second transmission region 52. In the photoelectric conversion device 1, the width of the second semiconductor region 28 in the normal direction of the third line L3 increases as it gets closer to the second transmission region 52 (in other words, further away from the first transmission region 51). The third line L3, for example, passes through the center in the direction of the width of the second semiconductor region 28. The first semiconductor region 27 is disposed on both sides of the second semiconductor region 28 in the direction of widening of the second semiconductor region 28 (i.e., the direction of the width of the second semiconductor region 28 in the normal direction of the third line L3). Furthermore, the width of the second semiconductor region 28 in the normal direction of the third line L3 can increase continuously or in stages.

[0067] In the third transfer region 53 configured as described above, a potential gradient (potential tilt) is formed, in which charge moves along the third line L3 from the first transfer region 51 side to the second transfer region 52 side. The principle is as follows: That is, in the portion of the third transfer region 53 near the first transfer region 51, such as... Figure 6 As shown in (a), the width of the second semiconductor region 28 is smaller than the width of the third transmission region 53, therefore the fringing effect of the first semiconductor regions 27 from both sides becomes stronger, and the potential ( Figure 6 The solid line shown in (a) becomes lighter. On the other hand, in the portion of the third transmission region 53 near the second transmission region 52, such as Figure 6 As shown in (b), the width of the second semiconductor region 28 is larger than the width of the third transmission region 53, therefore the edge effect of the first semiconductor regions 27 from both sides is weakened, and the potential ( Figure 6 The solid line shown in (b) becomes darker. As described above, in the third transfer region 53, the second semiconductor region 28 extends along the third line L3 in a manner that widens on the side of the second transfer region 52. Therefore, in the third transfer region 53, a potential gradient is formed in which charge moves along the third line L3 from the side of the first transfer region 51 to the side of the second transfer region 52. Furthermore, Figure 6 The dashed lines shown in (a) and (b) represent the potentials when the first semiconductor region 27 and the second semiconductor region 28 are individually present.

[0068] For the transfer of charge in the part of the transfer unit 5 that corresponds to the corner register 5c, refer to Figure 7 , Figure 8 and Figure 9 Please provide an explanation. Figure 7 , Figure 8 and Figure 9 yes Figure 3The diagram shows the potential of the transmission unit 5 (specifically, the portion of the transmission unit 5 corresponding to the corner register 5c). Furthermore, in this description, the transmission region adjacent to the upstream side of the first transmission region 51 is referred to as transmission region 61, and the transmission region adjacent to the downstream side of the second transmission region 52 is referred to as transmission region 62. Additionally, the transmission electrode disposed on transmission region 61 is referred to as transmission electrode 63, and the transmission electrode disposed on transmission region 62 is referred to as transmission electrode 64.

[0069] First of all, Ziroom Figure 7 As shown in (a), a low voltage is applied to the transfer electrode 63 and the second transfer electrode 56, a high voltage is applied to the first transfer electrode 55 and the transfer electrode 64, and a high voltage is applied to the third transfer electrode 57, as follows: Figure 7 As shown in (b) and (c), a low voltage is applied to the first transfer electrode 55 and the transfer electrode 64. Accordingly, the potentials of the first transfer region 51 and the transfer region 62 become shallower, and the potential of the transfer region 61 becomes a barrier, causing charge (electrons) to move from the first transfer region 51 to the third transfer region 53. At this time, in the third transfer region 53, a potential gradient (potential tilt) is formed, causing charge to move from the first transfer region 51 side to the second transfer region 52 side; therefore, in the third transfer region 53, charge moves towards the second transfer region 52 side. Furthermore, the potential of the second transfer region 52 becomes a barrier, and charge moves from the transfer region 62 to the downstream transfer region (not shown). In addition, Figure 7 (b) indicates the state in which the potential of the first transmission area 51 and the transmission area 62 is in the middle of changing.

[0070] Next, as Figure 8 As shown in (a), a high voltage is applied to the transfer electrode 63 and the second transfer electrode 56. Accordingly, the potential of the transfer region 61 and the second transfer region 52 deepens, and charge moves from the third transfer region 53 to the second transfer region 52. Additionally, charge moves from the upstream transfer region (not shown) to the transfer region 61. Then, as... Figure 8 As shown in (b), a low voltage is applied to the third transmission electrode 57. Accordingly, the potential of the third transmission region 53 becomes shallower. Then, as... Figure 8 As shown in (c), a high voltage is applied to the first transmission electrode 55 and the transmission electrode 64. Accordingly, the potential of the first transmission region 51 and the transmission region 62 increases.

[0071] Next, as Figure 9As shown in (a) and (b), a low voltage is applied to the transfer electrode 63 and the second transfer electrode 56. Accordingly, the potentials of transfer regions 61 and 52 become shallower, the potential of the third transfer region 53 becomes a barrier, and charge moves from the second transfer region 52 to the transfer region 62. Additionally, the potential of the upstream transfer region becomes a barrier, and charge moves from the transfer region 61 to the first transfer region 51. Furthermore, Figure 9 (a) indicates the state where the potentials of transmission area 61 and the second transmission area 52 are in the middle of transition. Next, as... Figure 9 As shown in (c), a high voltage is applied to the third transmission electrode 57. Accordingly, the potential of the third transmission region 53 deepens, and the return... Figure 7 The state shown in (a).

[0072] [Functions and Effects]

[0073] In the photoelectric conversion device 1, the transmission unit 5 (specifically, the portion of the transmission unit 5 corresponding to the angle register 5c) includes: a first transmission region 51 that transmits charge along a first line L1; a second transmission region 52 that transmits charge along a second line L2; and a third transmission region 53 that transmits charge from the first transmission region 51 side to the second transmission region 52 side along a third line L3 connected to the first line L1 and the second line L2, wherein the third line L3 is offset from both lines of the first line L1 and the second line L2. Accordingly, at least in the third transmission region 53, the direction of charge transmission is changed. In the third transmission region 53, a second semiconductor region 28 having a second impurity concentration higher than the first impurity concentration extends along the third line L3 in a manner that widens on the second transmission region 52 side, and a first semiconductor region 27 having a first impurity concentration is disposed on both sides of the second semiconductor region 28 in the direction of widening of the second semiconductor region 28. Accordingly, a potential gradient (potential tilt) is formed in the third transmission region 53, in which charge moves along the third line L3 from the first transmission region 51 side to the second transmission region 52 side. Therefore, it is not necessary to arrange more transmission electrodes in the third transmission region 53 to change the direction of charge transmission, etc. Therefore, according to the photoelectric conversion device 1, even if the direction of charge transmission in the transmission section 5 is changed, it is possible to avoid increasing the number of transmission electrodes and reliably transmit charge.

[0074] In the photoelectric conversion device 1, since the number of transmission electrodes in the transmission section 5 can be avoided, the following specific effects can be achieved: First, a decrease in yield due to increased structural complexity can be prevented. Second, high-speed driving can be prevented from being hindered by an increase in capacitance. Third, increased power consumption can be prevented.

[0075] In the photoelectric conversion device 1, the direction in which the second transmission region 52 transmits charge along the second line L2 is different from the direction in which the first transmission region 51 transmits charge along the first line L1. Accordingly, the direction of charge transmission can be changed in the transmission section 5.

[0076] In the photoelectric conversion device 1, the third line L3 is a curve. Accordingly, the direction of charge transmission can be smoothly changed in the transmission unit 5.

[0077] In the photoelectric conversion device 1, the transmission unit 5 has a third transmission electrode 57 disposed on the third transmission region 53. Accordingly, not only the potentials of the first transmission region 51 and the second transmission region 52 can be controlled, but also the potential of the third transmission region 53 can be controlled, thus enabling more reliable charge transmission.

[0078] In the photoelectric conversion device 1, the light-shielding layer 6 is disposed on the incident side of the light hν relative to the transmission unit 5. Accordingly, it is possible to prevent the generation of useless charges in the transmission unit 5 due to the light hν incident on it.

[0079] [Variation Example]

[0080] This disclosure is not limited to the embodiments described above. For example, such as Figure 10 As shown, the photoelectric conversion device 1 can be a surface-incident type solid-state camera. In Figure 10 In the photoelectric conversion device 1 shown, a semiconductor region 23 is formed within the semiconductor layer 22 along the surface 22a of the semiconductor layer 22, and an insulating film 7, a wiring layer 3, and a light-shielding layer 6 are arranged in this order on the surface 22a of the semiconductor layer 22. Figure 10 In the photoelectric conversion device 1 shown, light hν enters the photoelectric conversion unit 4 from the surface 22a side of the semiconductor layer 22 through the opening 6a of the light-shielding layer 6, the wiring layer 3 and the insulating film 7. Figure 10 The photoelectric conversion device 1 shown has Figure 11 The transmission unit 5 is shown. Figure 11 The transmission unit 5 shown is positioned at points on the incident side of light hν, where the first transmission electrode 55, the second transmission electrode 56, and the third transmission electrode 57 are disposed relative to the first transmission region 51, the second transmission region 52, and the third transmission region 53, respectively. Figure 4 The conveyor unit 5 shown is different. Furthermore... Figure 11 Is along with Figure 4 The same line (i.e., Figure 3 A cross-sectional view of the IV-IV line shown.

[0081] In addition, Figure 1 and Figure 2In the photoelectric conversion device 1 shown, the semiconductor substrate 21 can be thinned as a whole. In this case, the photoelectric conversion device 1 may also include a support substrate disposed opposite to the incident side of the light hν relative to the wiring layer 3.

[0082] In addition, Figure 1 and Figure 2 In the photoelectric conversion device 1 shown, when the frame portion surrounding the recess 24 in the semiconductor substrate 21 is positioned on the incident side of light hν relative to the horizontal shift register 5b, the corner register 5c, and the multiplication register 5d, the photoelectric conversion device 1 may not have a light-shielding layer 6. This is because when the semiconductor substrate 21 has a frame portion, even if light hν is incident on the frame portion and a charge is generated there, the charge is highly likely to disappear before reaching the semiconductor layer 22.

[0083] Alternatively, the transmission unit 5 may not have a transmission electrode (equivalent to the transmission electrode of the third transmission electrode 57 described above) disposed on the third transmission area 53. Figure 12 , Figure 13 and Figure 14 The transmission unit 5 shown has points where transmission electrodes are not disposed in the third transmission region 53, and points where the embedded layer 54 is disposed in the third transmission region 53, and... Figure 11 The conveyor unit 5 shown is different. Figure 12 , Figure 13 and Figure 14 In the transmission unit 5 shown, the buried layer 54 is disposed on one side of the third transmission region 53 in the Z-axis direction (the incident side of light hν in the Z-axis direction). That is, the buried layer 54 is disposed on the third transmission region 53. The buried layer 54 has a conductivity type different from that of the first semiconductor region 27 and the second semiconductor region 28. The buried layer 54 is, for example, formed within the semiconductor layer 22 by doping with a P-type impurity along the surface 22a of the semiconductor layer 22. + Type semiconductor region. According to... Figure 12 , Figure 13 and Figure 14 The transmission unit 5 shown does not require a transmission electrode to be placed on the third transmission region 53, thus simplifying the structure. Furthermore, the generation of dark current in the third transmission region 53 can be suppressed.

[0084] Furthermore, when the transmission unit 5 also functions as a photoelectric conversion unit, regardless of whether the transmission unit 5 has a third transmission electrode 57, and further, regardless of whether it has an embedded layer 54, the light-shielding layer 6 may not be provided on the incident side of the light hν relative to the transmission unit 5.

[0085] Furthermore, the direction in which the second transmission region 52 transmits charge along the second line L2 only needs to be different from the direction in which the first transmission region 51 transmits charge along the first line L1. For example, it can be as follows: Figure 15 As shown, the direction in which the second transmission region 52 transmits charge along the second line L2 forms a 90-degree angle with the direction in which the first transmission region 51 transmits charge along the first line L1. Alternatively, as... Figure 16 As shown, the direction of charge transmission in the second transmission region 52 along the second line L2 forms a 45-degree angle with the direction of charge transmission in the first transmission region 51 along the first line L1.

[0086] In addition, such as Figure 17 As shown, the first transmission area 51, the third transmission area 53, the second transmission area 52, the third transmission area 53, and the second transmission area 52 can be arranged in this order from the upstream side. In this case, for the third transmission area 53 on the downstream side, the second transmission area 52 adjacent to the upstream side of the third transmission area 53 on the downstream side is equivalent to the first transmission area 51.

[0087] Furthermore, if line L3 is offset from at least one of line L1 and line L2, then as follows Figure 18 As shown, the direction in which the second transmission region 52 transmits charge along the second line L2 can be the same as the direction in which the first transmission region 51 transmits charge along the first line L1. With this structure, even if the path of charge transmission in the transmission section 5 is changed, the number of transmission electrodes can be avoided, and charge can be reliably transmitted.

[0088] Furthermore, if line L3 is offset from at least one of line L1 and line L2, then it can be as follows: Figure 19 As shown, line L2 is not offset from line L1. Figure 19 In the transmission section 5 shown, the first line L1 and the second line L2 are located on the same straight line, and the third line L3 extends in a manner that deviates from the straight line and then returns to the straight line. With this structure, for example, when the object that the transmission section 5 should avoid is located between the first transmission area 51 and the second transmission area 52, and the transmission section 5 cannot be formed in a straight line, the number of transmission electrodes can be avoided, and the charge can be reliably transmitted.

[0089] Furthermore, the transfer of charge in the portion of the transfer unit 5 corresponding to the corner register 5c can be performed while the potential of the third transfer region 53 is fixed, regardless of whether the transfer unit 5 has the third transfer electrode 57. For a specific example, see [reference needed]. Figure 20 , Figure 21 and Figure 22 Please provide an explanation. Figure 20 , Figure 21 and Figure 22 yes Figure 12The diagram shows the potential of the transmission unit 5 (specifically, the portion of the transmission unit 5 corresponding to the corner register 5c). Furthermore, in this description, the transmission region adjacent to the upstream side of the first transmission region 51 is referred to as transmission region 61, and the transmission region adjacent to the downstream side of the second transmission region 52 is referred to as transmission region 62. Additionally, the transmission electrode disposed on transmission region 61 is referred to as transmission electrode 63, and the transmission electrode disposed on transmission region 62 is referred to as transmission electrode 64.

[0090] First of all, Ziroom Figure 20 As shown in (a), a low voltage is applied to the transmission electrode 63 and the second transmission electrode 56, and a high voltage is applied to the first transmission electrode 55 and the transmission electrode 64 (in this state, the potential of the third transmission region 53 is deeper than the potential of the transmission regions 61 and the second transmission region 52, and shallower than the potential of the first transmission region 51 and the transmission region 62), as Figure 20 As shown in (b) and (c), a low voltage is applied to the first transfer electrode 55 and the transfer electrode 64. Accordingly, the potentials of the first transfer region 51 and the transfer region 62 become shallower, and the potential of the transfer region 61 becomes a barrier, causing charge (electrons) to move from the first transfer region 51 to the third transfer region 53. At this time, in the third transfer region 53, a potential gradient (potential tilt) is formed, causing charge to move from the first transfer region 51 side to the second transfer region 52 side; therefore, in the third transfer region 53, charge moves towards the second transfer region 52 side. Furthermore, the potential of the second transfer region 52 becomes a barrier, and charge moves from the transfer region 62 to the downstream transfer region (not shown). In addition, Figure 20 (b) indicates the state in which the potential of the first transmission area 51 and the transmission area 62 is in the middle of changing.

[0091] Next, as Figure 21 As shown in (a), a high voltage is applied to the transfer electrode 63 and the second transfer electrode 56. Accordingly, the potential of the transfer region 61 and the second transfer region 52 deepens, and charge moves from the third transfer region 53 to the second transfer region 52. Additionally, charge moves from the upstream transfer region (not shown) to the transfer region 61. Then, as... Figure 21 As shown in (b), a high voltage is applied to the first transmission electrode 55 and the transmission electrode 64. Accordingly, the potential of the first transmission region 51 and the transmission region 62 deepens. Then, as... Figure 22 As shown in (a) and (b), a low voltage is applied to the transmission electrode 63 and the second transmission electrode 56. Accordingly, the potential of the transmission region 61 and the second transmission region 52 becomes shallower, and the voltage returns... Figure 20 The state shown in (a). Furthermore... Figure 22(a) indicates the state during the transition of the potentials of transmission region 61 and the second transmission region 52. During this transition, the potential of the third transmission region 53 becomes a barrier, and charge moves from the second transmission region 52 to the transmission region 62. In addition, the potential of the upstream transmission region becomes a barrier, and charge moves from the transmission region 61 to the first transmission region 51.

[0092] Furthermore, in any of the above-described methods and examples, the upstream end of the second semiconductor region 28 in the third transmission region 53 may be offset by a certain amount from the downstream end of the semiconductor region 25 in the first transmission region 51 (to the extent that it does not impede the movement of charge). Additionally, in any of the above-described methods and examples, the downstream end of the second semiconductor region 28 in the third transmission region 53 may be offset by a certain amount from the upstream end of the semiconductor region 26 in the second transmission region 52 (to the extent that it does not impede the movement of charge). Furthermore, in any of the above-described methods and examples, the P-type and N-type conductivity types may be opposite to the conductivity types described above. Furthermore, in any of the above-described methods and examples, the impurity concentration in each semiconductor region is not limited to the concentrations described above and may be appropriately varied.

[0093] Symbol Explanation

[0094] 1……Photoelectric conversion device; 4……Photoelectric conversion unit; 5……Transmission unit; 6……Light shielding layer; 27……First semiconductor region; 28……Second semiconductor region; 51……First transmission region; 52……Second transmission region; 53……Third transmission region; 54……Buried layer; 55……First transmission electrode; 56……Second transmission electrode; 57……Third transmission electrode; L1……First line; L2……Second line; L3……Third line.

Claims

1. A photoelectric conversion device comprising: a photoelectric conversion section that generates electric charges in accordance with incidence of light; and a transfer section that transfers the electric charges, the transfer section having: a first transfer region that transfers the electric charges along a first line; a second transfer region that transfers the electric charges along a second line; a third transfer region that transfers the electric charges from the first transfer region side to the second transfer region side along a third line that connects the first line and the second line; a first transfer electrode that is disposed on the first transfer region; and a second transfer electrode that is disposed on the second transfer region, the third line being offset from the line of at least one of the first line and the second line, the third transfer region including: a first semiconductor region having a first impurity concentration; and a second semiconductor region having a second impurity concentration that is higher than the first impurity concentration, the second semiconductor region extending along the third line in a manner that widens on the second transfer region side, the first semiconductor region being disposed on both sides of the second semiconductor region in a direction in which the second semiconductor region widens.

2. The photoelectric conversion device according to claim 1, wherein a direction in which the second transfer region transfers the electric charges along the second line is different from a direction in which the first transfer region transfers the electric charges along the first line.

3. The photoelectric conversion device according to claim 1, wherein the third line is a curved line.

4. The photoelectric conversion device according to claim 2, wherein the third line is a curved line.

5. The photoelectric conversion device according to any one of claims 1 to 4, wherein the transfer section further has a third transfer electrode that is disposed on the third transfer region.

6. The photoelectric conversion device according to any one of claims 1 to 4, wherein the transfer section further has a buried layer having a conduction type different from conduction types of the first semiconductor region and the second semiconductor region, the buried layer being disposed on the third transfer region.

7. The photoelectric conversion device according to any one of claims 1 to 4, further comprising: a light-blocking layer that is disposed on an incidence side of the light with respect to the transfer section.

8. The photoelectric conversion device according to claim 5, further comprising: a light-blocking layer that is disposed on an incidence side of the light with respect to the transfer section.

9. The photoelectric conversion device according to claim 6, further comprising: a light-blocking layer that is disposed on an incidence side of the light with respect to the transfer section.

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