Photoelectric conversion device, manufacturing method, and equipment

Abstract

To provide a technique for improving the detection capability of the directionality of light incident on a photoelectric conversion device.SOLUTION: A photoelectric conversion device includes a semiconductor substrate provided with at least one pixel having a plurality of photoelectric conversion elements that receive light from a common microlens, and the semiconductor substrate has a first surface consisting of a light receiving surface of the plurality of photoelectric conversion elements and a second surface opposite to the first surface, the first surface has a concave shape, and at least a portion of the first surface is inclined with respect to the second surface.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to photoelectric conversion devices, manufacturing methods, and equipment. [Background technology]

[0002] Patent Document 1 discloses a solid-state imaging device that is provided with two photoelectric conversion regions in one pixel and is capable of detecting the directivity of incident light by detecting the phase difference of the incident light. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-281296 A Summary of the Invention [Problem to be solved by the invention]

[0004] The solid-state imaging device disclosed in Patent Document 1 has an insufficient ability to detect the angle and directivity of light from a subject, and therefore has an insufficient ability to detect the phase difference of light from a subject. Therefore, the present application aims to provide a photoelectric conversion device with improved ability to detect the angle and directivity of light from a subject and high ability to detect phase difference, and a manufacturing method thereof. [Means for solving the problem]

[0005] One aspect of the present disclosure is a photoelectric conversion device comprising a semiconductor substrate having at least one pixel having a microlens and a plurality of photoelectric conversion elements directly below the microlens, wherein the semiconductor substrate has a first surface which is a light receiving surface of the plurality of photoelectric conversion elements and is concave, and at least a portion of the first surface is inclined with respect to a second surface opposite the first surface. Effect of the Invention

[0006] According to at least one embodiment of the present disclosure, it is possible to provide a technique for improving the detection capability of the angle and directivity of light incident on a photoelectric conversion device. [Brief description of the drawings]

[0007] [Figure 1] 1 is a block diagram of an imaging device according to a first embodiment. [Diagram 2] 1 is a schematic diagram of a pixel of an imaging device according to a first embodiment. [Diagram 3] 1 is a plan view of a pixel of an imaging device according to a first embodiment. [Figure 4] 2 is a circuit diagram of a pixel and a readout circuit of the imaging device according to the first embodiment. [Diagram 5] 4 is a timing chart of a unit pixel of the imaging device according to the first embodiment. [Figure 6] 1 is a comparison diagram between the imaging device according to the first embodiment and the conventional technology. [Figure 7] 4 is a graph showing the relative light amount and the light amount ratio with respect to the light incident angle Θ according to the first embodiment. [Figure 8] 6A and 6B are a cross-sectional view and a plan view of a pixel of an imaging device according to a second embodiment. [Figure 9] FIG. 11 is a plan view of a pixel of an imaging device according to a second embodiment. [Figure 10] FIG. 11 is a circuit diagram of a pixel and a readout circuit of an imaging device according to a second embodiment. [Figure 11] 10 is a timing chart of a unit pixel of an imaging device according to a second embodiment. [Figure 12] 11A and 11B are a cross-sectional view and a plan view of a pixel of an imaging device according to a third embodiment. [Figure 13] FIG. 13 is a plan view of a pixel of an imaging device according to a third embodiment. [Figure 14] 13A and 13B are a cross-sectional view and a plan view of a pixel of an imaging device according to a fourth embodiment. [Figure 15] 13A and 13B are a cross-sectional view and a plan view of a pixel of an imaging device according to a fifth embodiment. [Figure 16]13A and 13B are a cross-sectional view and a plan view of a pixel of an imaging device according to a sixth embodiment. [Figure 17] FIG. 13 is a plan view of a pixel of an imaging device according to a sixth embodiment. [Figure 18] FIG. 13 is a circuit diagram of a pixel and a readout circuit of an imaging device according to a sixth embodiment. [Figure 19] 13A and 13B are a cross-sectional view and a plan view of a pixel of an imaging device according to a seventh embodiment. [Figure 20] FIG. 13 is a plan view of a pixel of an imaging device according to a seventh embodiment. [Figure 21] FIG. 13 is a circuit diagram of a pixel and a readout circuit of an imaging device according to a seventh embodiment. [Figure 22] FIG. 13 is a schematic diagram of a device according to an eighth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In the following embodiments, an image pickup device will be mainly described as an example of a photoelectric conversion device. However, each embodiment is not limited to an image pickup device, and can be applied to other examples of photoelectric conversion devices. For example, a distance measuring device (a device for measuring distance using focus detection or TOF (Time Of Flight)) or a photometric device (a device for measuring the amount of incident light) may be used.

[0009] Furthermore, the disclosure of this specification includes the complement of the concepts described in this specification. In other words, if this specification contains a statement that "A is greater than B," even if the statement that "A is not greater than B" is omitted, this specification can be said to disclose that "A is not greater than B." This is because when a statement that "A is greater than B" is made, it is assumed that the case in which "A is not greater than B" is taken into consideration.

[0010] In addition, in this specification, a planar view refers to a plan view viewed from a direction perpendicular to the light incident surface of the semiconductor substrate or the surface opposite to the light incident surface, and corresponds to a two-dimensional plan view obtained by projecting each component of the photoelectric conversion device onto the surface of the semiconductor substrate.

[0011] (First embodiment) 1 is a block diagram of an imaging device in this embodiment. The imaging device 51 has a pixel array section 52, unit pixels 53, column signal lines 54, row signal lines 55, a readout circuit 56, a vertical scanning circuit 57, a horizontal scanning circuit 58, and a timing control circuit 59. A plurality of row signal lines 55 are provided for each unit pixel 53. The timing control circuit 59 outputs control pulses to the vertical scanning circuit 57 and the readout circuit 56. The unit pixel 53 corresponds to one pixel of an image file created by imaging in the imaging device 51.

[0012] 2A is a cross-sectional view and FIG. 2B is a plan view of two vertical and two horizontal unit pixels 53 in a pixel array section 52 of this embodiment. In FIG. 2, the unit pixels 53 include four photodiodes PD_A, PD_B, PD_C, and PD_D.

[0013] In FIG. 2(a), each unit pixel 53 has a PD_A N-type region 1, a PD_B N-type region 2, a semiconductor substrate 5, a P-type region 6, an N-type floating diffusion region 7, a gate electrode 8 of a transfer MOS transistor, a metal wiring 9, a fixed charge layer 10, an anti-reflection film 11, and a buried silicon oxide region 12.

[0014] A red color filter 13 is provided in the unit pixel 53 on the left side of the drawing, and a green color filter 14 is provided in the unit pixel 53 on the right side of the drawing. A microlens 15 is provided above each color filter. A photodiode separator 18 is provided in the region between PD_A and PD_B. Incident light 17 is incident on the unit pixel 53 from above, as shown in the drawing.

[0015] Fig. 2(b) is a cross-sectional view taken along line A-A' in Fig. 2(a). That is, Fig. 2(b) is a plan view seen from the side where incident light 17 enters. Fig. 2(a) is a cross-sectional view taken along plane C-C' in the plan view of Fig. 2(b). In Fig. 2(b), an N-type region 1 of PD_A, an N-type region 2 of PD_B, an N-type region 3 of PD_C, and an N-type region 4 of PD_D are shown.

[0016] The light receiving surface 16 of the unit pixel 53 has a concave shape and is a surface that is inclined with respect to the rear surface of the semiconductor substrate 5. In addition, it can be said that the angle of a part of the light receiving surface 16 of adjacent PDs is different.

[0017] In this embodiment, the concave shape formed by the light receiving surfaces 16 of adjacent PDs has the shape of the side surface of a quadrangular pyramid (hereinafter, referred to as a "quadrature pyramid shape"). It can also be said that the N-type regions of each photodiode do not overlap when viewed from the normal direction of the front or back surface of the semiconductor substrate 5.

[0018] A method for forming the light receiving surface 16 of this embodiment will be described. The concave shape of the light receiving surface 16 is formed by anisotropic wet etching or etching using a gray mask. When formed by anisotropic wet etching, for example, the angle of the slope of the quadrangular pyramid shape is 54°. When etching, it is desirable to form a resist mask on the boundary portion of the unit pixel 53.

[0019] A fixed charge layer 10 for suppressing dark current may be provided on the light receiving surface 16. The fixed charge layer 10 is preferably made of oxides of HF such as HFO (hafnium oxide) or oxides of AL (aluminum), TI (titanium), ZR (zirconium), or MG (magnesium). The fixed charge layer 10 may be formed by ALD (Atomic Layer Deposition), sputtering, electron beam deposition, plasma CVD (Chemical Vapor Deposition), or the like.

[0020] An anti-reflection film 11 such as SIN (silicon nitride) may be provided on the light incident surface side of the fixed charge layer 10. The anti-reflection film 11 is formed by a method such as a plasma CVD method. On the upper part of the anti-reflection film 11, SIO (silicon oxide) or the like is provided as a buried transparent region 12 that fills the recessed shape. The buried transparent region 12 is formed by a method such as a plasma CVD method.

[0021] A red color filter 13 and a green color filter 14 are provided on the buried transparent region 12. Before forming the color filters 13 and 14, it is preferable to planarize the buried transparent region 12 by a chemical mechanical polishing (CMP) method or the like.

[0022] 2(a), only the red color filter 13 and the green color filter 14 are shown, but a blue color filter (not shown) may be present in an adjacent pixel. A microlens 15 is provided above the color filters 13 and 14. Thus, a unit pixel 53 is formed.

[0023] Fig. 3 is a cross-sectional view taken along line B-B' in Fig. 2(a). In this embodiment, the elements of a readout circuit 56, such as a floating diffusion region 7, a transfer MOS transistor 8, and metal wiring 9, are provided on the surface opposite to the light-receiving surface 16. The floating diffusion region 7 becomes an electric capacitance through a PN junction with the P-type region 6, and the amount of charge stored in the capacitance is converted into a signal potential.

[0024] It is preferable that the N-type regions 1, 2, 3, and 4 of PD_A, PD_B, PD_C, and PD_D are configured so that the N-type impurities are concentrated near the transfer MOS transistor 8 provided on the surface opposite to the light receiving surface 16. By providing a concentration gradient of the impurities in this way, there is an advantage that the charges generated in each PD by the incident light 17 are collected near the transfer MOS transistor 8, and the transfer of the charges to the floating diffusion region 7 by the transfer MOS transistor 8 can be completed in a short time.

[0025] 4 is a circuit diagram of the pixel and readout circuit in this embodiment, in which TX_A, TX_B, TX_C, and TX_D represent transfer MOS transistors, RES represents a reset MOS transistor, SF represents a source follower transistor, and SEL represents a selection MOS transistor.

[0026] 5 is a timing chart showing the operation of the unit pixel 53 in this embodiment. At time T1, a pulse φSEL applied to the gate electrode of the selection MOS transistor SEL goes high, selecting this unit pixel 53. At the same time, a pulse φRES applied to the gate electrode of the reset MOS transistor RES goes high, resetting the N-type floating diffusion region 7.

[0027] At time T2, the pulse φRES applied to the gate electrode of the reset MOS transistor RES goes low, and the reset of the floating diffusion region 7 is released. At this time, the noise signal potential VN of the floating diffusion region 7 is sent to the column signal line 54 via the source follower transistor SF, and begins to be AD converted by the read circuit 56. At time T3, the AD conversion of the noise signal potential VN of the floating diffusion region 7 is completed.

[0028] At time T4, the pulse φTX_A applied to the gate electrode of the transfer MOS transistor TX_A goes high, and the charge stored in PD_A is transferred to the floating diffusion region 7. At time T5, the pulse φTX_A applied to the gate electrode of the transfer MOS transistor TX_A goes low, and a signal VA based on the charge stored in PD_A appears in the floating diffusion region 7 as a potential that becomes VA+VN. At the same time, AD conversion begins in the read circuit 56. AD conversion of the potential VA+VN ends at time T6.

[0029] At time T7, the pulse φTX_B applied to the gate electrode of the transfer MOS transistor TX_B goes high, and the charge accumulated in PD_B is transferred to the floating diffusion region 7. At time T8, the pulse φTX_B applied to the gate electrode of the transfer MOS transistor TX_B goes low, and a signal VB based on the charge accumulated in PD_B appears in the floating diffusion region 7 as a potential of VB+VA+VN. At the same time, AD conversion begins in the read circuit 56. At time T9, AD conversion of the potential VB+VA+VN ends. At this time, the charge accumulated in PD_A and the charge accumulated in PD_B are added together in the floating diffusion region 7.

[0030] At time T10, the pulse φTX_C applied to the gate electrode of the transfer MOS transistor TX_C goes high, and the charge stored in PD_C is transferred to the floating diffusion region 7. At time T11, the pulse φTX_C applied to the gate electrode of the transfer MOS transistor TX_C goes low, and a signal VC based on the charge stored in PD_C appears in the floating diffusion region 7 as a potential VC+VB+VA+VN. At the same time, AD conversion begins in the readout circuit 56. At time T12, AD conversion of the potential VC+VB+VA+VN ends.

[0031] At time T13, the pulse φTX_D applied to the gate electrode of the transfer MOS transistor TX_D goes high, and the charge stored in PD_D is transferred to the floating diffusion region 7. At time T14, the pulse φTX_D applied to the gate electrode of the transfer MOS transistor TX_D goes low, and a signal VD based on the charge stored in PD_D appears in the floating diffusion region 7 as a potential of VD+VC+VB+VA+VN. At the same time, AD conversion begins in the read circuit 56. AD conversion of the potential VD+VC+VB+VA+VN ends at time T12.

[0032] At time T14, the pulse φSEL applied to the gate electrode of the selection MOS transistor SEL goes low, and the selection of the unit pixel 53 ends.

[0033] The potentials VA, VB, VC, and VD are derived by a read circuit 56 and a signal processing circuit (not shown). The potential VA is derived by subtracting VN from the potential VA+VN. The potential VB is derived by subtracting VA+VN from VB+VA+VN. The potential VC is derived by subtracting VB+VA+VN from VC+VB+VA+VN. The potential VD is derived by subtracting VC+VB+VA+VN from VD+VC+VB+VA+VN.

[0034] From the difference between the potentials VA and VB, the horizontal direction directivity of the incident light 17 in the pixel array section 52 can be derived. Also, from the difference between the potentials VC and VD, the vertical direction directivity of the incident light 17 in the pixel array section 52 can be derived. That is, according to this embodiment, the directivity of the incident light can be derived as a two-dimensional angle.

[0035] FIG. 6 is a comparison diagram showing the effect of this embodiment. FIG. 6(a) is a cross-sectional view of a unit pixel of this embodiment, and FIG. 6(b) is a cross-sectional view of a conventional unit pixel. The surface of the conventional semiconductor substrate 5 on the light incident side is flat, not concave as in this embodiment. In the figure, p is the pitch of the unit pixels, h is the distance between the surface of the semiconductor substrate 5 and the microlens 15, and d is the distance between the apex of the quadrangular pyramid shape and the surface of the semiconductor substrate 5. Θ is the angle of incidence of the incident light, and Ψ is the angle between the ridge of the inverted pyramid and the plane of the semiconductor substrate 5.

[0036] Fig. 7 is a graph showing the effect of this embodiment. Fig. 7(a) shows the amount of light incident on PD_A and PD_B among the amount of light incident on each PD with respect to the light incident angle Θ. The amount of light shown here is the relative amount of incident light on each PD normalized with the amount of light entering one unit pixel 53 set to 1. For example, when the light incident angle Θ is 0°, 0.25 of light is incident on each of PD_A, PD_B, PD_C, and PD_D.

[0037] In Fig. 7(a), the thick line indicates the amount of light when there is a concave shape of Example 1, and the thin line indicates the amount of light when there is a conventional type without a concave shape. In this case, the unit pixel pitch p is 4 μm, h is 1 μm, and d is 2 μm. In this case, Ψ is 45°. As the light incident angle Θ increases, the difference in light amount between PD_A and PD_B increases, but the difference in light amount between PD_A and PD_B is more significantly greater when there is a concave shape than when there is a conventional type.

[0038] FIG. 7(b) shows the light intensity ratio of PD_A and PD_B with respect to the light incidence angle Θ. For example, when the light incidence angle Θ=20°, the concave shape of this embodiment has a 46% higher light intensity ratio than the conventional type. In other words, a pixel with a concave shape can react sensitively to the light incidence angle and has a high ability to detect oblique light. Therefore, the imaging device 51 having the concave shape of this embodiment has a high ability to detect the directivity of the incident light 17. In a camera using the imaging device 51 of this embodiment, the accuracy of phase difference autofocus is improved.

[0039] 7(b), the difference between this embodiment and the conventional type becomes larger as the light incidence angle Θ increases, so this embodiment is preferably effective when the imaging device 51 is applied to a situation where the distance between the camera lens and the imaging device 51 is short, for example, a smartphone, etc. In addition, this embodiment also has the effect of increasing the focus position adjustment range of the meta image file that allows the focus position adjustment of the image after shooting with the camera.

[0040] In the above description, the apex of the pyramid is located at the center of the unit pixel 53 in a plan view; however, this is not limited to the above, and the apex of the pyramid may be shifted from the center of the unit pixel 53 .

[0041] In the imaging device 51 of this embodiment, the color filters 13, 14 and the microlens 15 can be brought closer to the semiconductor substrate 5, so that optical color mixing can be reduced. The CMOS image sensor chip can also be made thinner to reduce its height. In addition, the junction area between the N-type regions 1, 2, 3, and 4 of PD_A, PD_B, PD_C, and PD_D and the P-type region 6 is increased, which has the effect of increasing the saturation charge.

[0042] In the above description, the color filters 13 and 14 and the microlens 15 are provided, but the color filters 13 and 14 may not be provided. For example, the unit pixel 53 shown in FIG. 2 may not include the microlens 15 and the color filters 13 and 14. In this case, the imaging device 51 is a monochrome imaging device. Even in this case, the detection capability of the directionality of the incident light 17 can be improved.

[0043] Second Embodiment In this embodiment, floating diffusion regions are provided corresponding to PD_A, PD_B, PD_C, and PD_D, respectively. Note that the same reference numerals as in the previous figures denote the same components in this figure, and the description thereof will be omitted.

[0044] 8A and 8B are a cross-sectional view and a plan view of two vertical unit pixels and two horizontal unit pixels of a pixel array section 52 in this embodiment. A unit pixel 63 in this embodiment has a floating diffusion region 7A for PD_A, a floating diffusion region 7B for PD_B, a floating diffusion region 7C for PD_C, and a floating diffusion region 7D for PD_D.

[0045] Fig. 8(b) is a plan view taken along the A-A' plane in the cross-sectional view of Fig. 8(a) and seen from the side where incident light 17 enters. Fig. 8(a) is a cross-sectional view taken along the C-C' plane in the cross-sectional view of Fig. 8(b). Like the unit pixel 53, the unit pixel 63 includes four photodiodes PD_A, PD_B, PD_C, and PD_D. Also, the light receiving surface of the unit pixel 63 has a concave shape like the first embodiment.

[0046] Fig. 9 is a plan view taken along the B-B' plane in the cross-sectional view of Fig. 8(a) and seen from the opposite side to the side into which incident light 17 enters. In this embodiment, floating diffusion regions 7A, 7B, 7C, and 7D are provided for PD_A, PD_B, PD_C, and PD_D, respectively.

[0047] Fig. 10 is a circuit diagram of a pixel and a readout circuit in this embodiment, and Fig. 11 is a timing chart of the unit pixel 63 of the CMOS area sensor chip 51 of the first embodiment.

[0048] At time T1, a pulse φSEL applied to the gate electrode of the selection MOS transistor SEL goes high, selecting this unit pixel 63. At the same time, a pulse φRES applied to the gate electrode of the reset MOS transistor RES goes high, resetting the N-type floating diffusion region 7.

[0049] At time T2, the pulse φRES applied to the gate electrode of the reset MOS transistor RES goes low, releasing the reset of the floating diffusion region 7. At this time, the noise signal potential VN of the floating diffusion region 7 is sent to the column signal lines 54A, 54B, 54C, and 54D via the source follower transistor SF, and begins to be AD converted by the read circuit 56. At time T3, the AD conversion of the noise signal potential VN of the floating diffusion region 7 is completed.

[0050] At time T4, a pulse φTX applied to the gate electrodes of the transfer MOS transistors TX_A, TX_B, TX_C, and TX_D goes high, and the charges stored in PD_A, PD_B, PD_C, and PD_D are transferred to the floating diffusion regions 7A, 7B, 7C, and 7D.

[0051] At time T5, a pulse φTX applied to the gate electrodes of the transfer MOS transistors TX_A, TX_B, TX_C, and TX_D goes low, a signal VA based on the charge accumulated in PD_A appears in the floating diffusion region 7 as a potential of VA+VN, and AD conversion begins in the readout circuit 56. Similarly, a signal VB based on the charge accumulated in PD_B appears in the floating diffusion region 7B as a potential of VB+VN, and AD conversion begins in the readout circuit 56. The same is true for VC+VN and VD+VN. AD conversion of the potentials VA+VN, VB+VN, VC+VN, and VD+VN ends at time T6.

[0052] At time T7, the pulse φSEL applied to the gate electrode of the selection MOS transistor SEL goes low, and the selection of the unit pixel 63 ends.

[0053] In the structure of this embodiment, as in the first embodiment, the detection capability of the directivity of the incident light 17 can be improved. In addition, the height of the imaging device can be reduced, so that optical color mixing can be reduced. In addition, the junction area between the N-type regions 1, 2, 3, and 4 of PD_A, PD_B, PD_C, and PD_D and the P-type region 6 is increased, which has the effect of increasing the saturation charge.

[0054] (Third embodiment) In this embodiment, the area of ​​the part corresponding to the bottom of the concave quadrangular pyramid shape of the light receiving surface of the photodiode is reduced, and a flat part is left. Note that the same reference numerals as in the previous figures represent the same parts in this figure, and the explanation thereof will be omitted.

[0055] Fig. 12 is a cross-sectional view (a) and a plan view (b) of two vertical unit pixels and two horizontal unit pixels of a pixel array section 52 of this embodiment. The pixel array section 52 has unit pixels 73. Fig. 12(b) is a plan view cut along the A-A' plane of the cross-sectional view of Fig. 12(a) and seen from the side where incident light 17 enters. Fig. 13 is a plan view cut along the B-B' plane of the cross-sectional view of Fig. 12(a) and seen from the opposite side to the side where incident light 17 enters.

[0056] The unit pixel 73 includes four photodiodes PD_A, PD_B, PD_C, and PD_D, similar to the unit pixel 53. The light receiving surface of the unit pixel 73 has a concave shape in the center.

[0057] The concave shape in this embodiment has a smaller bottom area of ​​the quadrangular pyramid shape than those in the first and second embodiments. In other words, a large flat portion 19 remains. The quadrangular pyramid shape is formed by anisotropic wet etching or etching using a gray mask. The flat portion 19 is formed by covering it with a resist mask during etching to prevent it from being etched.

[0058] Since the thickness of the semiconductor substrate 5 is, for example, 2 to 4 μm, by leaving the flat portion in this embodiment, it is possible to improve the mechanical strength of the semiconductor substrate 5 while increasing the detection ability of the directionality of the incident light 17.

[0059] (Fourth embodiment) The fourth embodiment is an example in which a flat portion is provided at the bottom of the concave shape of the light receiving surface of the photodiode. Note that the same reference numerals as in the previous figures denote the same parts in this figure, and the description thereof will be omitted.

[0060] Fig. 14 is a cross-sectional view (a) and a plan view (b) of two vertical unit pixels and two horizontal unit pixels of a pixel array section 52 of this embodiment. The pixel array section 52 has unit pixels 83. Fig. 14(b) is a plan view cut along the A-A' plane of the cross-sectional view of Fig. 14(a) and seen from the side where incident light 17 enters. Fig. 14(a) is a cross-sectional view cut along the C-C' plane of the plan view of Fig. 14(b).

[0061] In this embodiment, the concave shape of the light receiving surface has a flat bottom portion 20. The concave shape is formed by anisotropic wet etching or etching using a gray mask. The flat portion 19 is covered with a resist mask during etching to prevent it from being etched.

[0062] The structure of this embodiment provides high detection capability for the directivity of incident light 17, and increases the junction area between N-type regions 1, 2, 3, and 4 of PD_A, PD_B, PD_C, and PD_D and P-type region 6, thereby increasing the saturation charge.

[0063] Fifth embodiment This embodiment is an example in which the light receiving surface and the readout circuit are provided on the same surface of the semiconductor substrate 5. Note that the same reference numerals as in the previous figures denote the same components in this figure, and their explanation will be omitted.

[0064] Fig. 15 is a cross-sectional view (a) and a plan view (b) of two vertical unit pixels and two horizontal unit pixels of a pixel array section 52 of this embodiment. The pixel array section 52 has unit pixels 93. Fig. 15(b) is a plan view cut along the D-D' plane of the cross-sectional view of Fig. 15(a) and seen from the side where incident light 17 enters. Fig. 15(a) is a cross-sectional view cut along the E-E' plane of the plan view of Fig. 15(b).

[0065] In this embodiment, the incident surface of the incident light 17 and each element of the readout circuit 56, such as the floating diffusion region 7 and the transfer MOS transistor 8, are on the same surface side of the semiconductor substrate 5. Each element of the readout circuit 56 is provided on the flat portion 19 of the semiconductor substrate 5.

[0066] The structure of this embodiment has the effect of improving the detection capability of the directivity of the incident light 17, while providing the light receiving surface and the pixel readout system on the same surface of the semiconductor substrate 5, thereby reducing manufacturing costs.

[0067] Sixth embodiment This embodiment is an example in which the number of photodiodes per unit pixel is changed. Note that the same reference numerals as in the previous figures denote the same parts in this figure, and the description thereof will be omitted.

[0068] FIG. 16 is a cross-sectional view (A) and a plan view (B) of two vertical unit pixels and two horizontal unit pixels of a pixel array section 52 of Example 6. The pixel array section has unit pixels 43. FIG. 16(b) is a plan view cut along the D-D' plane of the cross-sectional view of FIG. 16(a) and seen from the side where incident light 17 enters. FIG. 16(a) is a cross-sectional view cut along the E-E' plane of the plan view of FIG. 16(b). FIG. 17 is a plan view cut along the F-F' plane of the cross-sectional view of FIG. 16(a) and seen from the side where incident light 17 enters. FIG. 18 is a circuit diagram of a pixel and a readout circuit in this embodiment.

[0069] The unit pixel 43 is provided with two photodiodes PD_A and PD_B, and has a concave shape in the center of the light receiving surface.

[0070] The two photodiodes may be arranged in the direction in which the row signal lines 55 of the imaging device 51 extend, or in the direction in which the column signal lines 54 extend. With this structure, the two-dimensional angle of the incident light can be derived.

[0071] 17 shows the arrangement of the first-layer metal wiring 21. The metal wiring 9 including the first-layer metal wiring 21 is preferably arranged at the edge of the unit pixel 43 so that as much incident light 17 as possible reaches PD_A and PD_B.

[0072] The structure of this embodiment can improve the detection capability of the directivity of incident light, as in the above embodiments. In addition, since only two photodiodes are provided in one unit pixel, the amount of light entering each photodiode is increased.

[0073] Seventh embodiment In this embodiment, a unit pixel having a divided photodiode and a unit pixel having an undivided photodiode are arranged in a pixel array. Note that the same reference numerals as those in the previous figures represent the same components in this figure, and the description thereof will be omitted.

[0074] FIG. 19 is a cross-sectional view (a) and a plan view (b) of two vertical unit pixels and two horizontal unit pixels of a pixel array section 52 of this embodiment. FIG. 19(b) is a plan view cut along the D-D' plane of the cross-sectional view of FIG. 19(a) and seen from the side where incident light 17 enters. FIG. 19(a) is a cross-sectional view cut along the E-E' plane of the plan view of FIG. 19(b). FIG. 20 is a plan view cut along the F-F' plane of the cross-sectional view of FIG. 19(a) and seen from the side where incident light 17 enters. FIG. 21 is a circuit diagram of a pixel and a readout circuit of this embodiment.

[0075] The pixel array section 52 has a unit pixel 33-1 in which the photodiode is divided, and a unit pixel 33-2 in which the photodiode is not divided. The unit pixel 33-2 has a photodiode PD_E. The unit pixel 33-1 has two photodiodes PD_A and PD_B. In other words, the unit pixel 33-2 has fewer photodiodes than the unit pixel 33-1.

[0076] In this embodiment, unit pixels 33-1 in which the photodiode is divided are included in only a part of the pixel array section 52. For example, in Fig. 19, of the four unit pixels, only one is a unit pixel 33-1 in which the photodiode is divided, and the remaining three unit pixels are unit pixels 33-2 in which the photodiode is not divided.

[0077] 20 shows the arrangement of the first-layer metal wiring 21. The metal wiring 9 including the first-layer metal wiring 21 is arranged at the ends of the unit pixels 33-1 and 33-2 so that as much incident light 17 as possible reaches PD_A and PD_B.

[0078] In this embodiment, the detection capability of the directionality of incident light is also high. In addition, by arranging unit pixels in which the photodiode is not divided, the number of metal wirings is reduced, and more incident light reaches the photodiode.

[0079] Eighth embodiment The eighth embodiment can be applied to any of the first to seventh embodiments. Fig. 22(a) is a schematic diagram for explaining an apparatus 9191 including a semiconductor device 930 of this embodiment. The semiconductor device 930 can be a photoelectric conversion device (imaging device) of each of the above-mentioned embodiments.

[0080] An apparatus 9191 including a semiconductor device 930 will be described in detail. As described above, the semiconductor device 930 can include a package 920 that houses the semiconductor device 910, in addition to the semiconductor device 910 having the semiconductor layer 10. The package 920 can include a base to which the semiconductor device 910 is fixed, and a lid such as glass that faces the semiconductor device 910. The package 920 can further include a bonding member such as a bonding wire or a bump that connects a terminal provided on the base and a terminal provided on the semiconductor device 910.

[0081] The device 9191 can include at least one of an optical device 940, a control device 950, a processing device 960, a display device 970, a storage device 980, and a mechanical device 990. The optical device 940 corresponds to the semiconductor device 930. The optical device 940 is, for example, a lens, a shutter, or a mirror. The control device 950 controls the semiconductor device 930. The control device 950 is, for example, a semiconductor device such as an ASIC.

[0082] The processing device 960 processes the signal output from the semiconductor device 930. The processing device 960 is a semiconductor device such as a CPU or ASIC for configuring an AFE (analog front end) or a DFE (digital front end). The display device 970 is an EL display device or a liquid crystal display device that displays information (images) obtained by the semiconductor device 930. The storage device 980 is a magnetic device or a semiconductor device that stores information (images) obtained by the semiconductor device 930. The storage device 980 is a volatile memory such as an SRAM or a DRAM, or a non-volatile memory such as a flash memory or a hard disk drive.

[0083] The mechanical device 990 has a moving part or a propulsion part such as a motor or an engine. In the device 9191, the signal output from the semiconductor device 930 is displayed on the display device 970, or transmitted to the outside by a communication device (not shown) included in the device 9191. For this purpose, the device 9191 preferably further includes a memory device 980 and a processing device 960 in addition to the memory circuit and arithmetic circuit included in the semiconductor device 930. The mechanical device 990 may be controlled based on the signal output from the semiconductor device 930.

[0084] The device 9191 is also suitable for electronic devices such as information terminals (e.g., smartphones and wearable devices) with a photographing function and cameras (e.g., interchangeable lens cameras, compact cameras, video cameras, and surveillance cameras). The mechanical device 990 in the camera can drive components of the optical device 940 for zooming, focusing, and shutter operation. Alternatively, the mechanical device 990 in the camera can move the semiconductor device 930 for vibration isolation operation.

[0085] The device 9191 may be transportation equipment such as a vehicle, a ship, or an aircraft. The mechanical device 990 in the transportation equipment may be used as a moving device. The device 9191 as a transportation equipment is suitable for transporting the semiconductor device 930 or for assisting and / or automating driving (piloting) by using a photographing function. The processing device 960 for assisting and / or automating driving (piloting) can perform processing for operating the mechanical device 990 as a moving device based on information obtained by the semiconductor device 930. Alternatively, the device 9191 may be a medical device such as an endoscope, a measuring device such as a distance measuring sensor, an analytical device such as an electron microscope, an office machine such as a copier, or an industrial device such as a robot.

[0086] According to the above-described embodiment, it is possible to obtain good pixel characteristics. Therefore, the value of the semiconductor device can be increased. In this case, increasing the value corresponds to at least one of adding functions, improving performance, improving characteristics, improving reliability, improving manufacturing yield, reducing environmental load, reducing costs, reducing size, and reducing weight.

[0087] Therefore, if the semiconductor device 930 according to this embodiment is used in the equipment 9191, the value of the equipment can be improved. For example, by mounting the semiconductor device 930 on a transport equipment, excellent performance can be obtained when photographing the outside of the transport equipment or measuring the external environment. Therefore, in manufacturing and selling the transport equipment, it is advantageous to decide to mount the semiconductor device according to this embodiment on the transport equipment in order to improve the performance of the transport equipment itself. In particular, the semiconductor device 930 is suitable for transport equipment that performs driving assistance and / or automatic driving of the transport equipment using information obtained by the semiconductor device.

[0088] The photoelectric conversion system and the moving object of this embodiment will be described with reference to FIGS.

[0089] Fig. 22(b) shows an example of a photoelectric conversion system related to an in-vehicle camera. The photoelectric conversion system 8000 has a photoelectric conversion device 80. The photoelectric conversion device 80 is the photoelectric conversion device (imaging device) described in any of the above embodiments. The photoelectric conversion system 8000 has an image processing unit 801 that performs image processing on a plurality of image data acquired by the photoelectric conversion device 80, and a parallax acquisition unit 802 that calculates parallax (phase difference of parallax images) from the plurality of image data acquired by the photoelectric conversion system 8000.

[0090] The photoelectric conversion system 8000 also includes a distance acquisition unit 803 that calculates the distance to the object based on the calculated parallax, and a collision determination unit 804 that determines whether or not there is a possibility of collision based on the calculated distance. Here, the parallax acquisition unit 802 and the distance acquisition unit 803 are examples of distance information acquisition means that acquire information on the distance to the object. That is, the distance information is information on the parallax, the defocus amount, the distance to the object, and the like. The collision determination unit 804 may determine the possibility of collision using any of these pieces of distance information.

[0091] The distance information acquisition means may be realized by dedicated hardware, a software module, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or a combination of these.

[0092] The photoelectric conversion system 8000 is connected to a vehicle information acquisition device 810 and can acquire vehicle information such as vehicle speed, yaw rate, steering angle, etc. The photoelectric conversion system 8000 is also connected to a control ECU 820, which is a control device that outputs a control signal for generating a braking force for the vehicle based on the determination result of the collision determination unit 804. The photoelectric conversion system 8000 is also connected to an alarm device 830 that issues an alarm to the driver based on the determination result of the collision determination unit 804.

[0093] For example, when the collision probability is high as a result of the judgment by the collision judgment unit 804, the control ECU 820 performs vehicle control to avoid the collision and reduce damage by applying the brakes, releasing the accelerator, suppressing the engine output, etc. The warning device 830 warns the user by sounding a warning, displaying warning information on the screen of a car navigation system, etc., applying vibrations to the seat belt or steering wheel, etc.

[0094] In this embodiment, the surroundings of the vehicle, for example, the front or rear, are imaged by the photoelectric conversion system 8000. Fig. 22(c) shows the photoelectric conversion system when imaging the area in front of the vehicle (imaging range 850). The vehicle information acquisition device 810 sends an instruction to the photoelectric conversion system 8000 or the photoelectric conversion device 80. With this configuration, the accuracy of distance measurement can be further improved.

[0095] Although the above describes an example of control to prevent collision with other vehicles, the present invention can also be applied to control of automatic driving by following other vehicles, control of automatic driving to prevent deviation from lanes, etc. Furthermore, the photoelectric conversion system is not limited to vehicles such as the vehicle itself, but can be applied to moving bodies (moving devices) such as ships, aircraft, and industrial robots. In addition, the present invention can be applied not only to moving bodies, but also to a wide range of devices that use object recognition, such as intelligent transport systems (ITS).

[0096] (Other embodiments) It should be noted that the above-mentioned embodiments are merely examples of the implementation of the present disclosure, and the technical scope of the present disclosure should not be interpreted as being limited by these. In other words, the present disclosure can be implemented in various forms without departing from its technical concept or main features. For example, combinations of the elements of the above-mentioned embodiments are also within the scope of the present disclosure.

[0097] In addition, each of the embodiments described above can be appropriately modified without departing from the scope of the technical concept. The disclosure of this specification includes not only what is described in this specification, but also all matters that can be understood from this specification and the drawings attached to this specification.

[0098] The disclosure of this embodiment includes the following configurations and methods.

[0099] (Configuration 1) a semiconductor substrate provided with at least one pixel having a plurality of photoelectric conversion elements that receive light from a common microlens; the semiconductor substrate has a first surface that is a light receiving surface of the plurality of photoelectric conversion elements and a second surface that faces the first surface; The first surface has a concave shape, and at least a portion of the first surface is inclined with respect to the second surface. A photoelectric conversion device comprising:

[0100] (Configuration 2) The pixel has an element isolation portion that isolates each of the plurality of photoelectric conversion elements from one another, 2. The photoelectric conversion device according to configuration 1, wherein the element isolation portion is provided at a position corresponding to a bottom portion of the recessed shape.

[0101] (Configuration 3) 3. The photoelectric conversion device according to configuration 1 or 2, wherein the plurality of photoelectric conversion elements are provided at positions that do not overlap when viewed from a normal direction of the second surface.

[0102] (Configuration 4) the pixel has a floating diffusion region; 4. The photoelectric conversion device according to any one of configurations 1 to 3, wherein the charges accumulated in each of the plurality of photoelectric conversion elements are added together in the floating diffusion region.

[0103] (Configuration 5) 5. The photoelectric conversion device according to any one of configurations 1 to 4, wherein an anti-reflection film is provided above the light receiving surface.

[0104] (Configuration 6) The photoelectric conversion device according to any one of configurations 1 to 5, wherein the pixel is provided with a readout circuit on the second surface of the semiconductor substrate, the readout circuit reading out a signal based on the signal charge of the photoelectric conversion element.

[0105] (Configuration 7) 7. The photoelectric conversion device according to configuration 6, wherein each of the plurality of photoelectric conversion elements has a higher N-type impurity concentration on a side where the readout circuit is provided than on a light receiving surface side.

[0106] (Configuration 8) The photoelectric conversion device according to any one of configurations 1 to 5, wherein the pixel includes a readout circuit between the photoelectric conversion element and the microlens, the readout circuit reading out a signal based on the signal charge of the photoelectric conversion element.

[0107] (Configuration 9) 9. The photoelectric conversion device according to configuration 8, wherein each of the plurality of photoelectric conversion elements has a higher N-type impurity concentration on a side where the readout circuit is provided than on the second surface side.

[0108] (Configuration 10) 10. The photoelectric conversion device according to any one of claims 1 to 9, wherein the semiconductor substrate has a plurality of the pixels.

[0109] (Configuration 11) 11. The photoelectric conversion device according to configuration 10, wherein the plurality of pixels includes a first pixel having two of the photoelectric conversion elements.

[0110] (Configuration 12) The pixel circuit further includes row signal lines extending in a row direction and column signal lines extending in a column direction, the first pixels include a pixel in which the two photoelectric conversion elements are arranged in a direction in which the row signal lines extend, and a pixel in which the two photoelectric conversion elements are arranged in a direction in which the column signal lines extend. 12. The photoelectric conversion device according to claim 11,

[0111] (Configuration 13) 11. The photoelectric conversion device according to configuration 10, wherein the plurality of pixels includes a second pixel having four of the photoelectric conversion elements.

[0112] (Configuration 14) the plurality of pixels further includes a third pixel having the photoelectric conversion element, The third pixel includes a smaller number of the photoelectric conversion elements than the first pixel. 12. The photoelectric conversion device according to claim 11,

[0113] (Configuration 15) A photoelectric conversion device including at least one pixel having a plurality of photoelectric conversion elements, A photoelectric conversion device, wherein adjacent photoelectric conversion elements have light incident surfaces with different angles.

[0114] (Configuration 16) The pixel further includes a microlens, and the pixel includes a plurality of photoelectric conversion elements on the light output side of the common microlens. 16. The photoelectric conversion device according to configuration 15,

[0115] (Configuration 17) An apparatus including the photoelectric conversion device according to any one of configurations 1 to 16, an optical device corresponding to the photoelectric conversion device; A control device for controlling the photoelectric conversion device; a processing device that processes a signal output from the photoelectric conversion device; a display device that displays information obtained by the photoelectric conversion device; a storage device that stores information obtained by the photoelectric conversion device; and and a mechanical device that operates based on information obtained by the photoelectric conversion device.

[0116] (Method 1) A method for manufacturing a photoelectric conversion device having a semiconductor substrate on which at least one pixel having a plurality of photoelectric conversion elements is provided on a light emission side of a common microlens, the method comprising the steps of: The method includes an etching step of etching the semiconductor substrate so that at least a part of a light receiving surface of the photoelectric conversion element provided on the first surface side of the semiconductor substrate is concave and inclined with respect to a second surface of the semiconductor substrate opposed to the first surface. A manufacturing method comprising the steps of:

[0117] (Method 2) A method for manufacturing a photoelectric conversion device having a semiconductor substrate provided with at least one pixel having a plurality of photoelectric conversion elements, comprising the steps of: The semiconductor substrate is etched so that the angles of the light receiving surfaces of the adjacent photoelectric conversion elements are different from each other. A manufacturing method comprising the steps of:

[0118] (Method 3) 3. The method according to method 1 or 2, wherein the etching step is performed by anisotropic wet etching. [Explanation of symbols]

[0119] 5. Semiconductor Substrates 15 Microlenses 16 Photosensitive surface 51 Imaging device (photoelectric conversion device) 53 pixels (unit pixel) PD photoelectric conversion element

Claims

1. a semiconductor substrate provided with at least one pixel having a plurality of photoelectric conversion elements that receive light from a common microlens; the semiconductor substrate has a first surface that is a light receiving surface of the plurality of photoelectric conversion elements and a second surface that faces the first surface; The first surface has a concave shape, and at least a portion of the first surface is inclined with respect to the second surface. A photoelectric conversion device comprising:

2. The pixel has an element isolation portion that isolates each of the plurality of photoelectric conversion elements from one another, The photoelectric conversion device according to claim 1 , wherein the element isolation portion is provided at a position corresponding to a bottom portion of the recessed shape.

3. The photoelectric conversion device according to claim 1 , wherein the plurality of photoelectric conversion elements are provided at positions that do not overlap each other when viewed from a normal direction of the second surface.

4. the pixel has a floating diffusion region; 2. The photoelectric conversion device according to claim 1, wherein the charges stored in each of the plurality of photoelectric conversion elements are added together in the floating diffusion region.

5. 2. The photoelectric conversion device according to claim 1, wherein an anti-reflection film is provided on the light receiving surface.

6. 2 . The photoelectric conversion device according to claim 1 , wherein the pixel includes a readout circuit provided on the second surface of the semiconductor substrate, the readout circuit reading out a signal based on a signal charge of the photoelectric conversion element.

7. 7. The photoelectric conversion device according to claim 6, wherein each of the plurality of photoelectric conversion elements has a higher N-type impurity concentration on a side where the readout circuit is provided than on a light receiving surface side.

8. 2. The photoelectric conversion device according to claim 1, wherein the pixel includes a read circuit between the photoelectric conversion element and the microlens, the read circuit reading out a signal based on a signal charge of the photoelectric conversion element.

9. 9. The photoelectric conversion device according to claim 8, wherein each of the plurality of photoelectric conversion elements has a higher N-type impurity concentration on a side where the readout circuit is provided than on a side of the second surface.

10. The photoelectric conversion device according to claim 1 , wherein the semiconductor substrate has a plurality of the pixels.

11. The photoelectric conversion device according to claim 10 , wherein the plurality of pixels includes a first pixel having two of the photoelectric conversion elements.

12. The pixel circuit further includes row signal lines extending in a row direction and column signal lines extending in a column direction, the first pixels include a pixel in which the two photoelectric conversion elements are arranged in a direction in which the row signal lines extend, and a pixel in which the two photoelectric conversion elements are arranged in a direction in which the column signal lines extend. The photoelectric conversion device according to claim 11 .

13. The photoelectric conversion device according to claim 10 , wherein the plurality of pixels includes a second pixel having four of the photoelectric conversion elements.

14. the plurality of pixels further includes a third pixel having the photoelectric conversion element, The third pixel includes a smaller number of the photoelectric conversion elements than the first pixel. The photoelectric conversion device according to claim 11 .

15. A photoelectric conversion device including at least one pixel having a plurality of photoelectric conversion elements, A photoelectric conversion device, wherein adjacent photoelectric conversion elements have light incident surfaces with different angles.

16. The pixel further includes a microlens, and the pixel includes a plurality of photoelectric conversion elements on the light output side of the common microlens. The photoelectric conversion device according to claim 15 .

17. A method for manufacturing a photoelectric conversion device having a semiconductor substrate on which at least one pixel having a plurality of photoelectric conversion elements is provided on a light emission side of a common microlens, the method comprising the steps of: The method includes an etching step of etching the semiconductor substrate so that at least a part of a light receiving surface of the photoelectric conversion element provided on the first surface side of the semiconductor substrate is concave and inclined with respect to a second surface of the semiconductor substrate opposed to the first surface. A manufacturing method comprising the steps of:

18. A method for manufacturing a photoelectric conversion device having a semiconductor substrate provided with at least one pixel having a plurality of photoelectric conversion elements, comprising the steps of: The semiconductor substrate is etched so that the angles of the light receiving surfaces of the adjacent photoelectric conversion elements are different from each other. A manufacturing method comprising the steps of:

19. 19. The method according to claim 17, wherein the etching step is performed by anisotropic wet etching.

20. An apparatus comprising the photoelectric conversion device according to any one of claims 1 to 16, an optical device corresponding to the photoelectric conversion device; A control device for controlling the photoelectric conversion device; a processing device that processes a signal output from the photoelectric conversion device; a display device that displays information obtained by the photoelectric conversion device; a storage device that stores information obtained by the photoelectric conversion device; and and a mechanical device that operates based on information obtained by the photoelectric conversion device.

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