Photoelectric conversion device, its manufacturing method, and imaging system

Abstract

To solve a problem in which: a conventional optical sensor does not have a sufficient difference in sensitivity between photodiodes.SOLUTION: A photoelectric conversion device has pixels each including a color filter formed on a substrate. The pixel includes, in an in-plane direction of the substrate, first photoelectric conversion units and second photoelectric conversion units having a lower sensitivity to light than that of the first photoelectric conversion units, and has, in a depth direction of the substrate, a first member between the first photoelectric conversion units and the color filter and a second member between the second photoelectric conversion units and the color filter. The first member is adjacent to the second member in the in-plane direction of the substrate. The refractive index of the first member is higher than that of the second member.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a photoelectric conversion device, a manufacturing method thereof, and an imaging system. [Background technology]

[0002] In recent years, there has been a demand for photoelectric conversion devices (optical sensors) with a wide dynamic range. Devices with a high dynamic range that can simultaneously capture dark and bright areas that conventional optical sensors cannot handle are advantageous for use in in-vehicle cameras and security cameras, for example, when there is a large difference between light and dark, such as in backlighting.

[0003] To achieve a high dynamic range, two or more photodiodes with different characteristics are combined to expand the dynamic range.

[0004] In order to achieve a high dynamic range, it is necessary to improve the characteristics of conventional optical sensors. As a prior art, in Patent Document 1, a high dynamic range is achieved by forming multiple photodiodes with different sensitivities by utilizing the difference in area between the photodiodes and combining these. In Patent Document 2, as another method, multiple photodiodes with different sensitivities are realized by forming neutral density filters with different transmittances on each photodiode. As a method of combining multiple photodiodes with different sensitivities, there is also a method of arranging photodiodes in a cascade structure as described in Patent Document 3. In Patent Document 4, an OFD (overflow drain) circuit is added to a high-sensitivity pixel to prepare for the case when the high-sensitivity pixel is saturated with strong light. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-218343 A [Patent Document 2] JP 2007-329721 A [Patent Document 3] US2018 / 0269245 [Patent Document 4] US2019 / 0131333 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventional optical sensors do not have sufficient sensitivity difference between photodiodes. [Means for solving the problem]

[0007] One aspect of the present invention is a photoelectric conversion device in which pixels each having a color filter are formed on a substrate, the pixels being arranged in an in-plane direction of the substrate as follows: Multiple The pixel includes a first photoelectric conversion unit and a second photoelectric conversion unit having a lower sensitivity to light than the first photoelectric conversion unit, and includes a first member between the first photoelectric conversion unit and the color filter in a depth direction of the substrate, and a second member between the second photoelectric conversion unit and the color filter, the first member being adjacent to the second member in an in-plane direction of the substrate, and a refractive index of the first member being higher than a refractive index of the second member. and in a plan view, at least a portion of one of the first photoelectric conversion units and at least a portion of the other first photoelectric conversion unit are arranged to overlap with the first member. It is characterized by:

[0008] Another aspect of the present invention is a photoelectric conversion device including a substrate having pixels, the pixels being arranged in an in-plane direction of the substrate as follows: Multiple The semiconductor laser includes a first photoelectric conversion unit and a second photoelectric conversion unit having a lower sensitivity to light than the first photoelectric conversion unit, and has an overflow transistor that discharges excess charge of the first photoelectric conversion unit, and in a depth direction of the substrate, a first member is provided on a light incident side of the first photoelectric conversion unit and a second member is provided on a light incident side of the second photoelectric conversion unit, the first member is adjacent to the second member in an in-plane direction of the substrate, and a refractive index of the first member is higher than a refractive index of the second member. and in a plan view, at least a portion of one of the first photoelectric conversion units and at least a portion of the other first photoelectric conversion unit are arranged to overlap with the first member. It is characterized by:

[0009] Yet another aspect of the present invention is a photoelectric conversion device including a substrate having pixels, the pixels being arranged in an in-plane direction of the substrate, the first conductivity type Multiple a first photoelectric conversion unit and a second photoelectric conversion unit of a first conductivity type having a lower impurity concentration of the first conductivity type than the first photoelectric conversion unit, a first member is provided on a light incident side of the first photoelectric conversion unit in a depth direction of the substrate, a second member is provided on a light incident side of the second photoelectric conversion unit, the first member is adjacent to the second member in an in-plane direction of the substrate, and a refractive index of the first member is higher than a refractive index of the second member and in a plan view, at least a portion of one of the first photoelectric conversion units and at least a portion of the other first photoelectric conversion unit are arranged to overlap with the first member. It is characterized by:

[0010] According to yet another aspect of the present invention, there is provided a photoelectric conversion device in which pixels each having a color filter are formed on a substrate, the pixels being arranged in an in-plane direction of the substrate as follows: Multiple The pixel includes a first photoelectric conversion unit and a second photoelectric conversion unit having a lower sensitivity to light than the first photoelectric conversion unit, the first photoelectric conversion unit and the second photoelectric conversion unit are located on a first plane parallel to the light incident surface of the substrate, and a first member overlapping the first photoelectric conversion unit and a second member overlapping the second photoelectric conversion unit are located adjacent to each other on a second plane parallel to the light incident surface of the substrate, the first member and the second member are both covered with the color filter, and a refractive index of the first member is higher than a refractive index of the second member. and in a plan view, at least a portion of one of the first photoelectric conversion units and at least a portion of the other first photoelectric conversion unit are arranged to overlap with the first member. It is characterized by:

[0011] Yet another aspect of the present invention is a method for producing a photoelectric conversion device having a color filter, comprising: Multiple No. 1 The semiconductor region and the 2 forming a semiconductor region of the 1 A second semiconductor region is disposed between the light incident surface side of the semiconductor region and a part of the color filter. 1 member and 2 and forming a second member disposed between the light incident surface side of the semiconductor region and a part of the color filter, the first member and the second member being adjacent to each other, and a refractive index of the first member and a refractive index of the second member being different from each other. and in a plan view, at least a portion of one of the first semiconductor regions and at least a portion of the other first semiconductor region are arranged to overlap with the first member. It is characterized by: Effect of the Invention

[0012] According to the present invention, it is possible to increase the sensitivity difference between photodiodes and improve the dynamic range characteristics. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating a schematic cross-sectional structure of a pixel of a photoelectric conversion device according to a first embodiment. [Diagram 2] 1 is a diagram illustrating a schematic planar structure of a pixel of a photoelectric conversion device according to a first embodiment. [Diagram 3] 11 is a diagram illustrating a schematic cross-sectional structure of a pixel of a photoelectric conversion device according to a second embodiment. [Figure 4] 11 is a diagram illustrating a planar structure of a pixel of a photoelectric conversion device according to a second embodiment. [Diagram 5] 2 is a configuration example of a pixel circuit of a photoelectric conversion device according to the first embodiment. [Figure 6] 3 is a schematic cross-sectional view illustrating an example of a method for manufacturing the photoelectric conversion device according to the first embodiment. [Figure 7] 2A to 2C are diagrams each showing a schematic cross-sectional structure illustrating an example of a method for manufacturing a photoelectric conversion device according to the first embodiment. [Figure 8A] 2A to 2C are diagrams each showing a schematic cross-sectional structure illustrating an example of a method for manufacturing a photoelectric conversion device according to the first embodiment. [Figure 8B] 2A to 2C are diagrams each showing a schematic cross-sectional structure illustrating an example of a method for manufacturing a photoelectric conversion device according to the first embodiment. [Figure 8C] 2A to 2C are diagrams each showing a schematic cross-sectional structure illustrating an example of a method for manufacturing a photoelectric conversion device according to the first embodiment. [Figure 8D] 2A to 2C are diagrams each showing a schematic cross-sectional structure illustrating an example of a method for manufacturing a photoelectric conversion device according to the first embodiment. [Figure 8E] 2A to 2C are diagrams each showing a schematic cross-sectional structure illustrating an example of a method for manufacturing a photoelectric conversion device according to the first embodiment. [Figure 8F]2A to 2C are diagrams each showing a schematic cross-sectional structure illustrating an example of a method for manufacturing a photoelectric conversion device according to the first embodiment. [Figure 8G] 2A to 2C are diagrams each showing a schematic cross-sectional structure illustrating an example of a method for manufacturing a photoelectric conversion device according to the first embodiment. [Figure 8H] 2A to 2C are diagrams each showing a schematic cross-sectional structure illustrating an example of a method for manufacturing a photoelectric conversion device according to the first embodiment. [Figure 8I] 2A to 2C are diagrams each showing a schematic cross-sectional structure illustrating an example of a method for manufacturing a photoelectric conversion device according to the first embodiment. [Figure 9] 11 is a diagram illustrating a cross-sectional structure showing an example of a method for manufacturing a photoelectric conversion device according to a second embodiment. [Figure 10A] 11 is a diagram illustrating a cross-sectional structure showing an example of a method for manufacturing a photoelectric conversion device according to a second embodiment. [Figure 10B] 11 is a diagram illustrating a cross-sectional structure showing an example of a method for manufacturing a photoelectric conversion device according to a second embodiment. [Figure 10C] 11 is a diagram illustrating a cross-sectional structure showing an example of a method for manufacturing a photoelectric conversion device according to a second embodiment. [Figure 10D] 11 is a diagram illustrating a cross-sectional structure showing an example of a method for manufacturing a photoelectric conversion device according to a second embodiment. [Figure 10E] 11 is a diagram illustrating a cross-sectional structure showing an example of a method for manufacturing a photoelectric conversion device according to a second embodiment. [Figure 11] FIG. 1 is a block diagram of an embodiment of an imaging system. [Figure 12] FIG. 2 is a block diagram of an embodiment of a mobile unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (Embodiment 1) An example of an embodiment for carrying out the present invention will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a diagram that illustrates a cross-sectional structure of a pixel of a photoelectric conversion device according to this embodiment, and Fig. 2 is a diagram that illustrates a planar structure of a pixel of a photoelectric conversion device according to this embodiment.

[0015] The configuration of the pixel shown in Fig. 1 will be described. The pixel shown in Fig. 1 includes a trench isolation 2001, a large-area photoelectric conversion section (large PD) 2002, and a small-area photoelectric conversion section (small PD) 2003 having an area smaller than that of the large-area photoelectric conversion section. It also includes an anti-reflection film 2004, a light-shielding wall 2005, a high-refractive index member 2006, a low-refractive index member 2007 having a refractive index smaller than that of the high-refractive index member, an inner lens 2008, and a color filter 2009. The large PD 2002 and the small PD 2003 are arranged adjacent to each other in the in-plane direction of the substrate (the direction parallel to the paper surface of Fig. 2).

[0016] The large PD 2002 and the small PD 2003 formed in the pixel do not need to be a single photodiode each, and may each be a combination of multiple photodiodes. In this case, the area of ​​the large PD 2002 and the small PD 2003 is the total area of ​​the photoelectric conversion parts of the multiple photodiodes that make up each.

[0017] Figure 1 shows an example in which the large PD 2002 consists of two photodiodes and the small PD 2003 consists of four photodiodes.

[0018] The high refractive index member 2006 has a relatively high refractive index, and is formed so as to overlap the large PD 2002 on the light incident surface side of the entire pixel. The low refractive index member 2007 has a relatively low refractive index, and is formed so as to overlap the small PD 2003 on the light incident surface side of the entire pixel. Light incident on the photoelectric conversion unit is light that has passed through at least one of the high refractive index member 2006 and the low refractive index member 2007. In other words, the large and small PDs, the high refractive index member, and the low refractive index member are formed so that there are a first plane on which the large PD and the small PD are arranged, and a second plane on the light incident surface side of the first plane on which the high refractive index member 2006 and the low refractive index member 2007 are arranged. The first plane and the second plane are virtual planes parallel to the light incident surface.

[0019] The inner lens 2008 is formed on the light incident side of the pixel, and is arranged so as to cover the large PD 2002 and the small PD 2003. The inner lens 2008 is arranged as necessary to converge light.

[0020] The light shielding wall 2005 is formed to prevent the incident light from interfering with adjacent pixels.

[0021] The trench isolation 2001 is formed to separate the photoelectric conversion unit of each pixel from the photoelectric conversion unit of an adjacent pixel within the semiconductor substrate and to prevent interference of accumulated charges.

[0022] The color filter 2009 is formed on the planarization layer 2010 so as to cover the high refractive index member 2006 and the low refractive index member 2007, sandwiching the inner lens 2008 and the planarization layer 2010. One color filter covers both the high refractive index member 2006 and the low refractive index member 2007. Therefore, when one color filter is projected onto the light incidence surfaces of the large PD 2002 and the small PD 2003, the projection of the color filter at least partially overlaps with each of the light incidence surfaces of the large PD 2002 and the small PD 2003. The color filter 2009 allows only light of a specific wavelength range (red light, green light, blue light, etc.) according to the type of color filter to enter the photoelectric conversion unit of the pixel in each pixel.

[0023] In addition, when a microlens for guiding incident light to a photoelectric conversion unit is provided on a pixel, for example, one microlens is arranged so as to cover both the large PD 2002 and the small PD 2003. Therefore, when one microlens is projected onto the light incident surface of the PD, the projection of the microlens at least partially overlaps with the light incident surfaces of the large PD 2002 and the small PD 2003. The projection of the microlens also at least partially overlaps with each of the high refractive index member 2006 and the low refractive index member 2007 arranged to overlap the large PD 2002 and the small PD 2003. The form of the microlens is not limited to this, and one or more microlenses may be used.

[0024] The relationship between the photoelectric conversion unit shown in FIG. 1 and the refractive index of a member disposed on the photoelectric conversion unit will be described below.

[0025] Fig. 2 is a plan view showing the positional relationship between the photoelectric conversion unit of the photoelectric conversion device in Fig. 1 and the members arranged on the photoelectric conversion unit. The light incident surface is on the back side in the direction perpendicular to the paper surface. A nested structure is formed with the small PD 2003 arranged on the outer edge of the pixel and the large PD 2002 arranged in the center of the pixel. As described above, the high refractive index member 2006 is arranged on the light incident surface side of the large PD 2002, and the low refractive index member 2007 is arranged adjacent to the high refractive index member 2006 on the light incident surface side of the small PD 2003.

[0026] When light is incident on this pixel, the incident light passes through the high refractive index member 2006 and the low refractive index member 2007. When members with different refractive indices, such as the high refractive index member 2006 and the low refractive index member 2007, are in contact with each other, the incident light is concentrated on the member with the higher refractive index, and less light is incident on the member with the low refractive index than when both members are not present. In a nested structure in which one member surrounds the other member and the contact surface between the high refractive index member 2006 and the low refractive index member 2007 becomes large, the incident light can be efficiently concentrated.

[0027] The light incident on the pixel via the high refractive index member 2006 and the low refractive index member 2007 is incident on each photoelectric conversion unit according to the area ratio of the large PD 2002 and the small PD 2003.

[0028] Therefore, the amount of light incident on the small PD 2003 arranged to overlap the low refractive index member 2007 is smaller than the amount of incident light determined due to the area ratio between the large PD and the small PD.

[0029] Similarly, since the large PD 2002 has a large area capable of efficiently collecting the incident light, and the incident light is concentrated by the high refractive index member 2006, the amount of light incident on the large PD 2002 is greater than the amount of incident light determined by the area ratio between the large PD and the small PD.

[0030] In this case, there is no restriction on the arrangement of the large PD 2002 and the small PD 2003 as long as they are arranged within the same pixel, and as long as the relationship between the refractive indexes of both members and the area of ​​both PDs match, the positions may be reversed from that shown in the drawing. Note that the sensitivity ratio of both PDs of a pixel and the refractive index ratio of both members must be set within a range in which the small PD 2003 can output a signal larger than the noise level before the output signal of the large PD 2002 becomes saturated, and this also applies to the second to fourth embodiments described later.

[0031] The components with different refractive indices may be made of dielectric materials, and an example of a combination is SiO2 with a refractive index of 1.46 and SiN with a refractive index of 2.00, but the materials of the components are not limited to this and can be any materials with different refractive indices.

[0032] By adopting a structure in which members with different refractive indices are arranged on the light incident surface side in this way, the large PD 2002 has a higher sensitivity and the small PD 2003 has a lower sensitivity. In other words, the difference in sensitivity between the large and small photoelectric conversion units is further increased, and the dynamic range of the pixel is widened.

[0033] As a result, the difference in sensitivity between photodiodes with different sensitivities arranged in one pixel can be made larger, making it possible to realize an optical sensor with a higher dynamic range at the same pixel pitch as conventional optical sensors.

[0034] (Embodiment 2) This embodiment will be described with reference to FIG. 3 and FIG.

[0035] In this embodiment, the dynamic range characteristics caused by differences in impurity concentration in the photoelectric conversion section can be expanded by the high refractive index member and the low refractive index member formed on the photoelectric conversion section.

[0036] Fig. 3 is a diagram showing a cross-sectional structure of a pixel of the photoelectric conversion device according to this embodiment, and Fig. 4 is a diagram showing a planar structure of a pixel of the photoelectric conversion device according to this embodiment. The description given in the first embodiment will be omitted, and the differences from the first embodiment will be mainly described.

[0037] As shown in FIG. 3, the pixel of FIG. 3 includes a trench isolation 2101, a high-concentration photoelectric conversion section (dark PD) 2102, a low-concentration photoelectric conversion section (light PD) 2103, an anti-reflection film 2104, a light-shielding wall 2105, a high-refractive index member 2106, and a low-refractive index member 2107.

[0038] In the pixel, a dark PD 2102 made of a semiconductor region with a relatively high impurity concentration and a thin PD 2103 having the same conductivity type as the dark PD 2102 and made of a semiconductor region with a relatively low impurity concentration are formed.

[0039] The high refractive index member 2106 has a relatively high refractive index and is formed on the light incident surface side of the entire pixel overlapping the dark PD 2102. The low refractive index member 2107 has a relatively low refractive index and is formed on the light incident surface side of the entire pixel overlapping the thin PD 2103.

[0040] In other words, the dark PD, thin PD, high refractive index member, and low refractive index member are formed so that there is a first plane in which the dark PD and thin PD are aligned, and a second plane in which the high refractive index member 2006 and the low refractive index member 2007 are aligned on the light incident surface side of the first plane.

[0041] The light shielding wall 2005 is formed to prevent the incident light from interfering with adjacent pixels.

[0042] The trench isolation 2101 is formed to separate each photoelectric conversion unit from the photoelectric conversion units of adjacent pixels within the semiconductor substrate and to prevent interference of accumulated charges.

[0043] The relationship between the difference in impurity concentration between the two types of photoelectric conversion units (thick PD and thin PD) shown in FIG. 3 and the difference in refractive index between the two types of refractive index members disposed on the photoelectric conversion units will be described below.

[0044] Fig. 4 is a plan view showing the positional relationship between the photoelectric conversion unit and the refractive index member arranged on the photoelectric conversion unit of the photoelectric conversion device in Fig. 3. As described above, the high refractive index member 2106 is arranged on the light incident surface side of the dark PD 2102, and the low refractive index member 2107 is arranged adjacent to the light incident surface side of the thin PD 2103.

[0045] When light is incident on this pixel, the incident light passes through the high refractive index member 2106 and the low refractive index member 2107. When members with different refractive indices are in contact with each other, such as the high refractive index member 2106 and the low refractive index member 2107, the incident light is concentrated in the member with the higher refractive index, and less light is incident on the member with the lower refractive index.

[0046] Light that is incident on the pixel and passes through the member is incident on the dark PD 2102 and the light PD 2103.

[0047] Therefore, the amount of light incident on the thin PD 2103 arranged over the low refractive index member 2107 is less than the amount of light incident on the thin PD 2103 in the absence of both components. Similarly, the amount of light incident on the dark PD 2102, in which the incident light is concentrated by the high refractive index member, is greater than the amount of light incident on the dark PD 2102 in the absence of both components.

[0048] Here, the dark PD 2102 has a higher impurity concentration than the light PD 2103, and therefore can hold more charges. In this embodiment, since the amount of light incident on the dark PD and the light PD is different, the difference in the amount of charge held in the dark PD and the light PD is larger than the difference in the amount of saturated charge determined by the impurity concentration ratio between the dark PD and the light PD.

[0049] In this case, there are no restrictions on the arrangement of the dark PD 2102 and the light PD 2103 as long as they are arranged within the same pixel, and as long as the relationship between the refractive index of the material and the impurity concentration of the photoelectric conversion section is consistent, the positions may be reversed from those shown in the figure.

[0050] By adopting a structure in which members with different refractive indices are arranged on the light incident surface side in this way, a lot of light is focused on the dark PD 2102, which can hold more charge, and only a small amount of light is incident on the thin PD 2103, which can hold less charge. In other words, each PD becomes less likely to saturate, and the difference in sensitivity between the photoelectric conversion parts of the dark PD and the thin PD becomes even larger.

[0051] As a result, photodiodes with different sensitivities can be efficiently arranged within one pixel, making it possible to realize a sensor with a higher dynamic range at the same pixel pitch as conventional photosensors.

[0052] (Example of embodiment 1) Next, an example of the first embodiment will be described with reference to the circuit diagram of FIG.

[0053] FIG. 5 shows an example of achieving high dynamic range characteristics using a different principle from those used in FIGS.

[0054] 5 shows an equivalent circuit of the pixel circuit according to this embodiment. The configuration will be described below.

[0055] 5 includes a first photodiode PD1 and a second photodiode PD2. The pixel circuit includes transfer switches 304 and 306, an overflow transistor 302, and an FD capacitance CFD. The pixel circuit further includes a gain control switch 314, a capacitance element Clg, a reset switch 312, a source follower transistor 316, and a select switch 318.

[0056] The function and connections of each element are explained below.

[0057] The first photodiode PD1 and the second photodiode PD2 are each an example of a photoelectric conversion unit. When light is incident on the first photodiode PD1 and the second photodiode PD2, charges are generated by photoelectric conversion. Each of the first photodiode PD1 and the second photodiode PD2 accumulates the generated charges as signal charges.

[0058] The source of transfer switch 304 is electrically connected to the cathode of the first photodiode PD1, and the drain of transfer switch 304 is electrically connected to the input node (gate) of source follower transistor 316. The source of transfer switch 306 is electrically connected to the cathode of the second photodiode PD2, and the drain of transfer switch 306 is electrically connected to the input node of source follower transistor 316.

[0059] Control signals TX1A and TX2 are respectively input to the gates of transfer switches 304 and 306. When each control signal is at a high level, signal charges are transferred from each photodiode to the input node of source follower transistor 316.

[0060] The drain of overflow transistor 302 is connected to power supply VDD. The source of overflow transistor 302 is connected to the cathode of the first photodiode PD1. Control signal AB1A is input to the gate of overflow transistor 302. In overflow transistor 302, a potential barrier is formed according to the gate potential. When control signal OF is at a high level, signal charges are transferred from the first photodiode PD1 to power supply VDD. When control signal AB1A is at an intermediate potential LM1 (Low < LM1 < High), the potential barrier between power supply VDD and the first photodiode PD1 becomes lower than the barriers in other regions, so that surplus charges can be discharged to power supply VDD.

[0061] The drains of transfer switches TX1A and TX2, the source of gain control switch 314, and the gate of source follower transistor 316 are connected to each other, forming one node. This one node may be referred to as a floating diffusion (hereinafter FD) node or FD section. In FIG. 5, the capacitance of the FD section is represented as FD capacitance CFD. The FD capacitance CFD may include the parasitic capacitance components of the wiring constituting the FD section and the parasitic capacitance components of the gates of the transistors connected to the FD section. Also, the FD capacitance CFD may include the PN junction capacitance components of the semiconductor regions constituting the FD section and the PN junction capacitance components of the sources or drains of the transistors connected to the FD section. In addition to these capacitance components, the FD capacitance CFD may be constituted by capacitance elements such as PIP capacitance, MIM capacitance, and MOS capacitance. When these capacitance elements are arranged, one end of the capacitance element is connected to the drains of transfer switches TX1A and TX2, the source of gain control switch 314, and the gate of source follower transistor 316.

[0062] The drain of gain control switch MGC is connected to one terminal of capacitance element Clg and the source of reset switch MRES. A control signal GC is input to the gate of gain control switch MGC. By setting the control signal GC to the Low level and turning off the gain control switch MGC while charge is accumulated in the capacitance element Clg, the capacitance element Clg is separated from the capacitance CFD. Also, by switching the control signal GC between the High level and the Low level and switching the on / off state of the gain control switch MGC, it is possible to switch whether to treat the capacitance element Clg as part of the FD capacitance, and to vary the gain of the charge-voltage conversion. Furthermore, when the control signal GC is at the intermediate potential LM1 (Low < LM1 < High), the potential barrier between the capacitance element Clg and the second photodiode PD2 becomes lower than the barriers in other regions, allowing surplus charge to be discharged from the capacitance element Clg.

[0063] A power supply VDD is connected to the drain of the reset switch 312 and the drain of the source follower transistor 316. A control signal FD-RST is input to the gate of the reset switch 312. When the control signal FD-RST is at a high level, the reset switch 312 is turned on. By turning on the reset switch 312, it is possible to reset the first photodiode PD1, the second photodiode PD2, the FD section, and part or all of the capacitance element Clg.

[0064] The source of the source follower transistor 316 is connected to a vertical output line 322 via a select switch 318. A control signal RS is input to the gate of the select switch 318. When the control signal RS is at a high level, the select switch 318 turns ON, and a source follower circuit is formed by the source follower transistor 316 and the current source.

[0065] The anode of the first photodiode PD1 and the anode of the second photodiode PD2 are each connected to a ground potential, and the other terminals of the capacitances CFD and Clg are each described as being connected to the ground potential.

[0066] The second photodiode PD2 includes an area where the potential is low for electrons, which are signal charges, and a potential barrier against the signal charges is formed around the area. That is, an area where the potential is locally high exists in the cathode of the second photodiode PD2. Therefore, the generated signal charge is accumulated in the cathode of the second photodiode PD2. As the electrons, which are signal charges, are accumulated, the cathode potential of the second photodiode PD2 decreases. As a result, the height of the potential barrier formed around the second photodiode PD2 decreases.

[0067] Among the charges generated by photoelectric conversion, there are cases where an excess charge is generated that exceeds the amount that can be stored in the photodiode. When a large amount of light is incident on the second photodiode PD2 and an excess charge is generated, the excess charge overflows from the lowest point of the potential barrier.

[0068] A transfer switch 306 is present between the second photodiode PD2 and the FD section, and a gain control switch 314 is present between the FD section and the capacitance element Clg. A gate potential TX2 of the transfer switch 306 can control the height of the potential barrier in the region immediately below the gate of the transfer switch 306, i.e., the channel region of the transfer switch 306. Similarly, a gate potential GAIN_CTRL of the gain control switch 314 can control the height of the potential barrier in the region immediately below the gate of the gain control switch 314, i.e., the channel region of the gain control switch 314.

[0069] The control signal TX2 of the transfer switch 306 is controlled so that the potential barrier between the photodiode PD2 and the FD section is the lowest among the potential barriers surrounding the periphery of the photodiode. At this time, excess charge generated in the second photodiode PD2 is discharged via the transfer switch 306. If the gain control switch 314 is off, the discharged excess charge is held in the FD section. The on / off of the gain control switch 314 is controlled by a control signal GAIN_CTRL input to the gain control switch 314. If the gain control switch 314 is on, the discharged excess charge is held in the FD section and the capacitance element Clg.

[0070] By using such a pixel circuit, three types of signals can be read out: a signal based on the charge accumulated in the first photodiode PD1, a signal based on the charge accumulated in the second photodiode PD2, and a signal based on the charge that overflows from the second photodiode PD2 and accumulates in the FD section and the capacitance element Clg. By reading out each of these three types of signals, it is possible to expand the dynamic range.

[0071] The relationship between the refractive index of the photoelectric conversion portion and the refractive index of a member disposed on the photoelectric conversion portion will be described below.

[0072] In this embodiment, a high refractive index member is disposed on the light incident surface side of the first photodiode PD1, and a low refractive index member is disposed adjacent to the high refractive index member on the light incident surface side of the second photodiode PD2. Note that the area of ​​the first photodiode PD1 is larger than that of the second photodiode PD2.

[0073] As described above, when light is incident on this pixel, the incident light is concentrated on one of the photoelectric conversion units due to the difference in refractive index between the high refractive index member and the low refractive index member.

[0074] Therefore, the amount of light incident on PD2, which is disposed over the low refractive index member, is less than the amount of incident light determined due to the area ratio between PD1 and PD2. On the other hand, the amount of light incident on PD1, which is disposed over the high refractive index member, is more than the amount of incident light determined due to the area ratio between PD1 and PD2.

[0075] By adopting a structure in which members with different refractive indices are arranged on the light incident surface side of the photodiodes PD1 and PD2 in this way, the difference in sensitivity between the photoelectric conversion units can be increased, and the range of light that each of the three types of signals in this embodiment corresponds to becomes wider. As a result, the sensitivity ratio of the photodiodes with different sensitivities arranged in one pixel can be increased, and an optical sensor with higher dynamic range characteristics can be realized with the same pixel pitch as conventional optical sensors.

[0076] Although described here as a specific example of embodiment 1, the application of this embodiment is not limited to embodiment 1, and it is also possible to increase the sensitivity difference of the photoelectric conversion unit in embodiment 2 by using the circuit shown in FIG. 2E.

[0077] (Manufacturing method 1) A method for manufacturing a photoelectric conversion device corresponding to the first embodiment will be described below.

[0078] In the manufacturing method described below, a circuit board and a photodiode board are separately manufactured, and the two boards are bonded together to manufacture a photoelectric conversion device.

[0079] First, a circuit board on which a peripheral circuit is formed is manufactured.

[0080] The formation of a silicon semiconductor element and a contact plug 3005 will be described with reference to FIG. 6A.

[0081] First, silicon semiconductor elements such as transistors 3003 are formed on a silicon substrate 3001. The elements are isolated from each other by an STI element isolation structure 3002. Thereafter, a contact interlayer insulating film 3004 is deposited by a CVD method, and the deposited contact interlayer insulating film 3004 is planarized by a CMP method to insulate the silicon semiconductor elements.

[0082] Subsequently, a contact plug 3005 is formed.

[0083] A mask is formed of photoresist on the contact interlayer insulating film 3004 by an exposure process. The contact interlayer insulating film 3004 outside the mask is removed by a dry etching process, and a via hole for electrically connecting the semiconductor elements is formed. The inner wall of the via hole is coated with a barrier metal made of a high melting point material such as tungsten by a sputtering method or the like, and the inside of the via hole is filled with the high melting point material by a CVD method or the like. The tungsten film outside the via hole is then removed by a CMP method, leaving tungsten only inside the via hole, forming a contact plug 3005.

[0084] Next, a procedure for forming a copper wiring layer by the damascene method will be described with reference to FIG. 6B.

[0085] First, an insulating film 3101 is deposited on the contact interlayer insulating film 3004, and a photoresist pattern is created on this insulating film 3101 by an exposure process. According to the created photoresist pattern, a trench and, if necessary, a via hole are formed by a dry etching method. The inner walls of the trench and the via hole are covered with a barrier metal by a sputtering method, and the inside is filled with copper by a copper plating method. Excess copper deposited is polished by a CMP method to form copper wiring 3102 as shown in FIG. 6B. The upper part of the formed copper wiring 3102 is covered with a Cu diffusion prevention film 3103 that prevents the diffusion and oxidation of copper.

[0086] The same process is repeated a required number of times to form copper wiring, resulting in a laminated structure as shown in FIG. 6B.

[0087] The formation of the aluminum wiring and bonding layer will be described with reference to FIG. 6C.

[0088] After the copper wiring layer is formed, an AL wiring is formed as necessary. For example, as shown in FIG. 6C, an interlayer insulating film 3201 is deposited. An AL wiring 3203, which also serves as a connection pad, is formed on the interlayer insulating film 3201 via a tungsten plug 3202, and an insulating film 3204 is deposited on the AL wiring, thereby forming the AL wiring. The AL wiring is not essential.

[0089] Finally, a bonding layer is formed to be used for bonding the circuit board to another photodiode board. After flattening the previous insulating film 3204 by the CMP method and eliminating the step, an insulating film 3205 is deposited on the insulating film 3204 by the CVD method. A photoresist pattern is formed on the insulating film 3205. A trench and a via hole are formed by an etching process, a barrier metal is deposited inside the via hole, copper is further deposited by copper plating, and excess Cu is removed by the CMP method. In this way, a bonding metal layer 3206 is formed by combining a trench and a contact plug filled with copper inside the via hole by the Cu damascene method. Finally, the surface of this circuit board has a structure consisting of partly Cu wiring and partly insulating film. This board becomes the circuit board 3000.

[0090] Next, the photodiode substrate is manufactured.

[0091] The basic manufacturing method is the same as that for circuit boards, but an additional process is used to create the photodiodes.

[0092] The formation of the photodiode, silicon semiconductor element, and contact plug will be described with reference to FIG. 7A.

[0093] First, an STI element isolation structure 4002 is formed in a silicon substrate 4001 .

[0094] At this time, the photomask is designed so that the areas of the photoelectric conversion portion A 4006 and the photoelectric conversion portion B 4007 are suitable according to the characteristics of the photodiode. In this example, the area of ​​the photoelectric conversion portion A is larger than the area of ​​the photoelectric conversion portion B. Through an exposure process, an etching process, an ion implant process, a film formation process, and the like, each photodiode including the photoelectric conversion portion A and the photoelectric conversion portion B is formed. In parallel with the formation of the photodiode, the necessary silicon semiconductor elements such as the transistor 4003 are formed. Thereafter, a contact interlayer insulating film 4004 is deposited by a CVD method and planarized by a CMP method to insulate the silicon semiconductor elements.

[0095] Subsequently, a contact plug 4005 is formed.

[0096] A mask is formed on the contact interlayer insulating film 4004 using photoresist by an exposure process, and a via hole necessary for electrically connecting semiconductor elements is formed through a dry etching process. The inner wall of the via hole is coated with a barrier metal made of a high melting point material such as tungsten by a sputtering method, and the inside of the via hole is filled with the high melting point material by a CVD method. After that, unnecessary tungsten film outside the via hole is removed by a CMP method, and tungsten remains only inside the via hole, forming a contact plug 4005.

[0097] Next, the wiring layer shown in FIG. 7B is formed using a damascene method.

[0098] First, an insulating film 4101 is deposited on the contact interlayer insulating film 4004. A photoresist pattern is created on this insulating film 4101 through an exposure process, and a trench and, if necessary, a via hole are formed by dry etching. The inner walls of the trench and the via hole are covered with a barrier metal by sputtering, and the interior is filled with copper by copper plating. Excess copper deposited is polished by CMP, and copper wiring 4102 shown in FIG. 4B is formed. The upper part of the formed copper wiring is covered with a Cu diffusion prevention film 4103 that prevents the diffusion and oxidation of copper.

[0099] The same process is repeated a required number of times to form a copper wiring process. After forming the copper wiring layer having a laminated structure as shown in FIG. 7B, an aluminum wiring is formed as necessary, but the aluminum wiring is not essential.

[0100] For example, as shown in FIG. 7C, an interlayer insulating film 4201 is deposited, an Al wiring 4203 that also serves as a connection pad is formed via a tungsten plug 4202, and an insulating film 4204 is deposited thereon to form an Al wiring.

[0101] Finally, a bonding layer is formed which is used to attach the photodiode substrate to another circuit board.

[0102] The insulating film 4204 is planarized by CMP to eliminate any steps that may have occurred during deposition. After that, an insulating film 4205 is deposited on 4204 by CVD. Using the Cu damascene method, a mask is formed by an exposure process, via holes are formed by an etching process, barrier metal is deposited in the via holes, Cu is deposited by Cu plating, and excess Cu is removed by CMP to form a bonding metal layer 4206. Finally, the surface of this photodiode substrate has a structure that is partly made of Cu wiring and partly made of insulating film. This substrate becomes the photodiode substrate 4000.

[0103] As the next step, the process of bonding the two substrates, the photodiode substrate (4000) and the circuit substrate (3000), is shown in detail in FIG.

[0104] Referring to FIG. 8A,

[0105] After activating the substrate surfaces with the bonding metal layers of the photodiode substrate 4000 and the circuit substrate 3000 with N2 plasma, the activated surfaces are placed facing each other and bonded together using a bonding device. An annealing process is then performed at 200°C to 450°C to improve adhesion. After the annealing process, the surface 5001 of the photodiode substrate 4000 opposite the surface bonded to the circuit substrate 3000 is polished to thin the Si substrate layer to approximately 3 μm. This thinned surface 5002 becomes the light incidence surface.

[0106] As shown in FIG. 8B, a DTI element isolation trench 5003, an Al2O3 pinning film 5004, and a Ta2O5 anti-reflection film 5005 are formed on a light incident surface 5002.

[0107] First, a trench structure is formed on the light incident surface 5002 through the formation of a mask by an exposure process and a dry etching process. Next, a pinning film 5004 for reducing dark current and an antireflection film 5005 for light are deposited. For example, Al2O3, HfO2, HfSiO4, etc. can be used for the pinning film 5004, and Ta2O5, SiN, SiON, etc. can be used for the antireflection layer. Other materials may be used as long as they serve the same purpose.

[0108] The total thickness of the pinning film 5004 and the anti-reflection film 5005 is less than 300 nm.

[0109] Furthermore, the PE-CVD method, ALD method, or SA-CVD method is used to fill in the trench portions that are not yet fully filled, and an insulating film is deposited in the trench structure to form a DTI element isolation trench 5003. If each pixel is arranged in a sufficiently wide area, this DTI element isolation trench 5003 may not be necessary.

[0110] Next, a process of forming a member having a refractive index A and a member having a refractive index B, in which the refractive index A is greater than the refractive index B, will be described with reference to FIG. 8C.

[0111] First, a member 5006 having a refractive index B is deposited on the anti-reflection film 5005 so as to overlap the small-area photoelectric conversion unit B 4007 in the depth direction. The member 5006 may be, for example, a SiO film formed by a PE-CVD method, a SiN film, a SiON film, a SiOCH film which is a low-K film, or an organic film containing C, O, S, H, etc. formed by a coating method.

[0112] Next, a region for forming a member having a refractive index A is secured in the member having a refractive index B.

[0113] In order to place a member with a refractive index A on photoelectric conversion section A, a photoresist pattern 5007 is formed to match the shape of the member with a refractive index A. Unnecessary portions of the member with a refractive index B are removed by dry etching using photoresist pattern 5007, forming grooves 5008 on photoelectric conversion section A. Photoresist that is no longer necessary is removed through an ashing and peeling process.

[0114] Thereafter, a member 5009 having a refractive index A is deposited on the member having a refractive index A and the member having a refractive index B, thereby obtaining the state shown in FIG. 8D.

[0115] At this time, it is necessary to deposit a component with a refractive index (refractive index A) greater than that of the component with refractive index B, such as a SiN film formed by PE-CVD as the component with refractive index A. This component with refractive index A can be made of a material that has a relatively high refractive index compared to the component with refractive index B, and can be, for example, a SiN film, a SiON film, a SiOCH film which is a low-k film, or an organic film containing C, O, S, H, etc. formed by a coating method. Optical materials containing two or more of Si, N, O, H, C, and S are generally used. Any unevenness on the surface after the component is deposited is polished by the CMP method, or flattened using an etch-back method, etc.

[0116] Finally, a structure is obtained in Fig. 8E, which has a member 5010 with a refractive index A and a member 5006 with a refractive index B. Members 5006 and 5010 are formed to a thickness within a range of 0.3 µm to 3.0 µm, and this thickness can be adjusted according to optical characteristics such as the size of the photodiode, the refractive index of the insulating film, and the shapes of the inner lens and microlens.

[0117] As described above, the total thickness of the pinning film 5004 and the anti-reflection film 5005 is less than 300 nm, and the member with refractive index A and the member with refractive index B are formed directly on the anti-reflection film 5005. Therefore, when assuming a first plane on which the large PD and the small PD are aligned, and a second plane on the light incident surface side of the first plane on which the high refractive index member 2006 and the low refractive index member 2007 are aligned, the pinning film 5004 and the anti-reflection film 5005 are present between the first plane and the second plane. The distance between the first plane and the second plane can be 300 nm or less.

[0118] The formation of the light-shielding wall will now be described.

[0119] According to FIG. 8F, after forming members 5006 and 5010 suitable for the characteristics of the photodiode, an insulating film 5011 is deposited, and further a light shielding wall 5012 is formed for each pixel to prevent light from leaking sideways.

[0120] The light shielding wall 5012 can be formed by forming a mask by, for example, an exposure process, and forming a trench by a dry etching method using the formed mask. The inner wall of the formed trench is covered with a barrier metal by a sputtering method, and tungsten is embedded in the trench by a tungsten CVD method. At this time, the excess tungsten material covering the top surface of the photodiode can be removed by a CMP method.

[0121] The formation of the inner lens will now be described.

[0122] As shown in Fig. 8G, in the next step after the formation of the light-shielding wall, an inner lens material 5013 is deposited, and photoresist 5014 is processed into a lens shape through an exposure process and a reflow process. An inner lens 5015 is formed by a dry etching process using the photoresist processed on the lens as a mask (Fig. 8H). Note that the inner lens 5015 may not be necessary if sufficient optical properties are obtained.

[0123] After the inner lens 2015 is formed, a planarization layer 5016 is deposited on the inner lens 5015, and surface irregularities are removed by a CMP method or the like. As shown in FIG. 8I, a light-shielding wall 5017 is formed as necessary using a method similar to that for the light-shielding wall 5012.

[0124] Finally, a color filter material corresponding to the color assigned to each pixel is applied, and exposed and developed to form a color filter layer 5018. This process is repeated according to the number of required colors.

[0125] A material that will become a microlens is applied onto the color filter layer 5018, exposed, developed, and formed into a microlens shape through a reflow process, thereby obtaining a microlens 5019.

[0126] (Manufacturing method 2) A method for producing a photoelectric conversion device according to the second embodiment will be described below.

[0127] In the manufacturing method described below, a circuit board and a photodiode board are manufactured, and the two boards are bonded together to manufacture a photoelectric conversion device. The method for forming the circuit board is omitted since it is the same as that shown in Figs. 6A to 6C, and the differences from Manufacturing Method 1 of the first embodiment will be mainly described.

[0128] 9A to 9C show a procedure for forming the photodiode substrate of this embodiment.

[0129] The formation of a photodiode and a silicon semiconductor element is described (FIG. 9A).

[0130] This manufacturing method is characterized in that, in FIG. 9A, the N-type carrier regions of the photoelectric conversion units C6006 and D6007 are formed according to the characteristics of the photodiode. The N-type carrier concentration of the photoelectric conversion unit C6006 is higher than the N-type carrier concentration of the photoelectric conversion unit D6007. Low The photoelectric conversion unit C6006 has a higher saturation charge per unit area than the photoelectric conversion unit D6007. Less The conditions of the ion implantation process are adjusted so as to achieve this.

[0131] Through an exposure process, an etching process, an ion implant process, a film formation process, and the like, photodiodes including photoelectric conversion units C and D are formed, and in parallel, silicon semiconductor elements such as the necessary transistors 6003 are formed. Thereafter, a contact interlayer insulating film 6004 is deposited by the CVD method and planarized by the CMP method to insulate the silicon semiconductor elements.

[0132] The steps shown in Figures 9B to 9C are similar to those shown in Figures 7B to 7C, and therefore will not be described here. By this manufacturing method, the structure shown in Figure 6C is finally obtained.

[0133] FIG. 10A illustrates the process from bonding the circuit board and the photodiode board to the anti-reflection film formation process.

[0134] Similar to the description of FIG. 8A, following bonding of the circuit board and the photodiode substrate, the photodiode substrate is thinned to form a light incident surface 7002.

[0135] Thereafter, the formation of the DTI element isolation trench 7003, the deposition of the AL2O3 pinning film 7004, and the deposition of the Ta2O5 anti-reflection film 7005 are also performed in the same manner. At this time, as long as the materials serve the same purpose, materials other than those exemplified in the explanation of Fig. 8B may be used. The total thickness of the AL2O3 pinning film 7004 and the Ta2O5 anti-reflection film 7005 is less than 300 nm.

[0136] Finally, the DTI element isolation trench 7003 is filled with an oxide film to obtain the structure shown in Fig. 10A. If each pixel is arranged in a sufficiently wide area, this DTI element isolation trench 7003 may not be necessary, as explained in Fig. 8B.

[0137] Next, a procedure for forming members C and D such that the refractive index of member D is greater than the refractive index of member C will be described.

[0138] First, as shown in Fig. 10B, a member 7006 having a refractive index D is deposited on an anti-reflection film 7005 so as to overlap in the depth direction with a photoelectric conversion section D6007 having a low N-type carrier concentration. This may be, for example, a SiO film formed by a PE-CVD method, a SiN film, a SiON film, a SiOCH film which is a low-K film, or an organic film containing C, O, S, H, etc. formed by a coating method.

[0139] Next, an area for forming a member with refractive index C is secured in the member with refractive index D. In order to place the member with refractive index C on the photoelectric conversion section C, a photoresist pattern 7007 is formed that matches the shape of the member with refractive index D. Unnecessary portions of the member with refractive index D are removed by dry etching using the photoresist pattern 7007, forming a groove portion 7008 on the photoelectric conversion section C. The photoresist that is no longer necessary is removed through an ashing and peeling process.

[0140] Thereafter, a member 7010 having a refractive index C is deposited on the member having a refractive index D to obtain the state shown in FIG. 10C.

[0141] At this time, it is necessary to deposit the material so that the refractive index C component, such as a SiN film made by PE-CVD, has a smaller refractive index (refractive index C) than the refractive index D component. The refractive index C component is relatively To The refractive index is low Any material can be used, for example, SiN film, SiON film, SiOCH film which is a low-k film, or organic film containing C, O, S, H, etc. can be formed by a coating method. Generally, optical materials containing two or more of Si, N, O, H, C, and S are used. After the materials are deposited, any unevenness on the surface is polished by the CMP method, or flattened by an etch-back method, etc.

[0142] Finally, a structure of a member 7010 having a refractive index C and a member 7006 having a refractive index D as shown in FIG. 10D is obtained.

[0143] Moreover, the member 7006 with the refractive index D and the member 7010 with the refractive index C are formed to a thickness within a range from 0.3 μm to 3.0 μm. This thickness can be adjusted according to optical characteristics such as the size of the photodiode, the refractive index of the insulating film, and the shapes of the inner lens and microlens.

[0144] Through the steps up to this point, the semiconductor substrate shown in FIG. 10D was obtained.

[0145] At this time, the differences between FIG. 8E and FIG. 10D are as follows.

[0146] In Fig. 8E, a material with a relatively high refractive index is placed on a photodiode with a relatively large and high sensitivity, and a material with a relatively low refractive index is placed on a photodiode with a relatively small and low sensitivity. In Fig. 10D, a material with a relatively high refractive index is placed on a photodiode with a relatively high impurity concentration and high sensitivity, and a material with a relatively low refractive index is placed on a photodiode with a low impurity concentration and low sensitivity.

[0147] Thereafter, the same steps as those shown in FIGS. 8F to 8I are carried out to obtain the structure shown in FIG. 10E.

[0148] Finally, a manufacturing method for realizing the embodiment shown in FIG. 5 will be described.

[0149] In order to form a circuit board having the circuit shown in FIG. 5, a pattern for forming an OFD circuit is added to a photomask used when forming transistors in the manufacturing process of the circuit board.

[0150] The procedure for forming the photodiode substrate and the procedure after bonding the circuit substrate and the photodiode substrate are not limited to the above-mentioned manufacturing method 1 and manufacturing method 2, and other methods may be used.

[0151] Additionally, the pixels may be front-illuminated or back-illuminated CMOS sensors.

[0152] (Embodiment 3) An embodiment of an imaging system will be described. Examples of imaging systems include digital cameras, digital camcorders, camera heads, copiers, fax machines, mobile phones, car-mounted cameras, observation satellites, etc. Fig. 11 shows a block diagram of a digital camera as an example of an imaging system.

[0153] In Fig. 11, 1001 is a barrier for protecting a lens. 1002 is a lens that forms an optical image of a subject on an imaging device 1004. 1003 is an aperture for varying the amount of light that has passed through the lens 1002. The imaging device 1004 uses the photoelectric conversion device described in each of the above examples and embodiments.

[0154] Reference numeral 1007 denotes a signal processing unit that performs processes such as correction and data compression on pixel signals output from the imaging device 1004 to obtain an image signal. In Fig. 11, reference numeral 1008 denotes a timing generating unit that outputs various timing signals to the imaging device 1004 and the signal processing unit 1007, and reference numeral 1009 denotes an overall control unit that controls the entire digital camera. Reference numeral 1010 denotes a frame memory unit for temporarily storing image data. Reference numeral 1011 denotes an interface unit for recording or reading data from a recording medium. Reference numeral 1012 denotes a removable recording medium such as a semiconductor memory for recording or reading image data. Reference numeral 1013 denotes an interface unit for communicating with an external computer or the like.

[0155] It should be noted that the imaging system only needs to have at least the imaging device 1004 and a signal processing unit 1007 that processes pixel signals output from the imaging device 1004. In this case, the other components are disposed outside the imaging system.

[0156] As described above, in the embodiment of the imaging system, the imaging device according to either the first or second embodiment is used as the imaging device 1004. With this configuration, the dynamic range of the image obtained from the imaging device can be expanded.

[0157] (Embodiment 4) An embodiment of a moving body will be described. The moving body of this embodiment is an automobile equipped with an on-board camera. Fig. 12(a) shows a schematic view of the exterior and main internal structure of an automobile 2200. The automobile 2200 includes an imaging device 2202, an integrated circuit for the imaging system (ASIC: Application Specific Integrated Circuit) 2203, an alarm device 2212, and a main control unit 2213.

[0158] The imaging device 2202 uses the imaging device described in each of the above-mentioned embodiments. The alarm device 2212 issues a warning to the driver when it receives a signal indicating an abnormality from the imaging system, the vehicle sensor, the control unit, etc. The main control unit 2213 comprehensively controls the operations of the imaging system, the vehicle sensor, the control unit, etc. Note that the automobile 2200 does not need to include the main control unit 2213. In this case, the imaging system, the vehicle sensor, and the control unit each have a communication interface, and each transmits and receives a control signal via a communication network (for example, CAN standard).

[0159] 12(b) is a block diagram showing the system configuration of an automobile 2200. The automobile 2200 includes a first imaging device 2202 and a second imaging device 2202. That is, the vehicle-mounted camera of this embodiment is a stereo camera. An object image is formed on the imaging device 2202 by an optical unit 2214. A pixel signal output from the imaging device 2202 is processed by an image pre-processing unit 2215 and then transmitted to an imaging system integrated circuit 2203. The image pre-processing unit 2215 performs processes such as SN calculation and addition of a synchronization signal.

[0160] The integrated circuit 2203 for imaging system includes an image processing unit 2204, a memory 2205, an optical distance measuring unit 2206, a parallax calculation unit 2207, an object recognition unit 2208, an abnormality detection unit 2209, and an external interface (I / F) unit 2216. The image processing unit 2204 processes pixel signals to generate image signals. The image processing unit 2204 also corrects the image signals and complements abnormal pixels. The memory 2205 temporarily holds the image signals. The memory 2205 may also store the positions of known abnormal pixels of the imaging device 2202. The optical distance measuring unit 2206 focuses or measures the distance of the object using the image signals. The parallax calculation unit 2207 performs object matching (stereo matching) of the parallax images. The object recognition unit 2208 analyzes the image signals to recognize objects such as automobiles, people, signs, and roads. The abnormality detection unit 2209 detects a failure or malfunction of the imaging device 2202. When the abnormality detection unit 2209 detects a failure or malfunction, it sends a signal indicating the detection of the abnormality to the main control unit 2213. The external I / F unit 2216 mediates the exchange of information between each unit of the imaging system integrated circuit 2203 and the main control unit 2213 or various control units, etc.

[0161] The automobile 2200 includes a vehicle information acquisition unit 2210 and a driving support unit 2211. The vehicle information acquisition unit 2210 includes vehicle sensors such as a speed / acceleration sensor, an angular velocity sensor, a steering angle sensor, a distance measuring radar, and a pressure sensor.

[0162] The driving support unit 2211 includes a collision determination unit. The collision determination unit determines whether or not there is a possibility of collision with an object based on information from the optical distance measurement unit 2206, the parallax calculation unit 2207, and the object recognition unit 2208. The optical distance measurement unit 2206 and the parallax calculation unit 2207 are examples of distance information acquisition means for acquiring distance information to an object. That is, the distance information is information on parallax, defocus amount, distance to the object, and the like. The collision determination unit may use any of these pieces of distance information to determine the possibility of collision. The distance information acquisition means may be realized by dedicated hardware or may be realized by a software module.

[0163] An example has been described in which the driving assistance unit 2211 controls the automobile 2200 so as not to collide with other objects, but the present invention can also be applied to control of automatic driving to follow other vehicles, or automatic driving to avoid straying from a lane.

[0164] The automobile 2200 further includes drive units used for driving, such as airbags, accelerators, brakes, steering, and a transmission. The automobile 2200 also includes control units for these drive units. The control units control the corresponding drive units based on control signals from the main control unit 2213.

[0165] The imaging system used in this embodiment can be applied not only to automobiles but also to moving bodies (moving devices) such as ships, aircraft, industrial robots, etc. In addition, the imaging system 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).

[0166] As described above, in the embodiment of the automobile, the imaging device according to any one of the first and second embodiments is used as the imaging device 2202. With such a configuration, it is possible to expand the dynamic range of the image obtained from the imaging device. [Explanation of symbols]

[0167] 100 pixels 2002 First photoelectric conversion section 2003 Second photoelectric conversion section 2006 First component 2007 2nd component 2009 Color Filter

Claims

1. A photoelectric conversion device in which pixels each having a color filter are formed on a substrate, the pixel includes, in an in-plane direction of the substrate, a plurality of first photoelectric conversion units and a second photoelectric conversion unit having a lower sensitivity to light than the first photoelectric conversion units; a first member is provided between the first photoelectric conversion unit and the color filter in a depth direction of the substrate, and a second member is provided between the second photoelectric conversion unit and the color filter; the first member is adjacent to the second member in an in-plane direction of the substrate, The refractive index of the first member is higher than the refractive index of the second member, A photoelectric conversion device characterized in that, when viewed in a planar view, at least a portion of one of the multiple first photoelectric conversion units and at least a portion of the other first photoelectric conversion unit are arranged so as to overlap the first member.

2. A photoelectric conversion device including a substrate having pixels, the pixel includes, in an in-plane direction of the substrate, a plurality of first photoelectric conversion units and a second photoelectric conversion unit having a lower sensitivity to light than the first photoelectric conversion units; an overflow transistor that drains excess charge from the first photoelectric conversion unit; a first member is provided on a light incident side of the first photoelectric conversion unit in a depth direction of the substrate, and a second member is provided on a light incident side of the second photoelectric conversion unit; the first member is adjacent to the second member in an in-plane direction of the substrate, The refractive index of the first member is higher than the refractive index of the second member, A photoelectric conversion device characterized in that, when viewed in a planar view, at least a portion of one of the multiple first photoelectric conversion units and at least a portion of the other first photoelectric conversion unit are arranged so as to overlap the first member.

3. 3. The photoelectric conversion device according to claim 1, wherein an area of ​​the first photoelectric conversion portion is larger than an area of ​​the second photoelectric conversion portion.

4. A photoelectric conversion device including a substrate having pixels, the pixel includes, in an in-plane direction of the substrate, a plurality of first photoelectric conversion units of a first conductivity type, and a second photoelectric conversion unit of the first conductivity type having a lower impurity concentration of the first conductivity type than the first photoelectric conversion units; a first member is provided on a light incident side of the first photoelectric conversion unit in a depth direction of the substrate, and a second member is provided on a light incident side of the second photoelectric conversion unit; the first member is adjacent to the second member in an in-plane direction of the substrate, The refractive index of the first member is higher than the refractive index of the second member, A photoelectric conversion device characterized in that, when viewed in a planar view, at least a portion of one of the multiple first photoelectric conversion units and at least a portion of the other first photoelectric conversion unit are arranged so as to overlap the first member.

5. A photoelectric conversion device in which pixels each having a color filter are formed on a substrate, the pixel includes, in an in-plane direction of the substrate, a plurality of first photoelectric conversion units and a second photoelectric conversion unit having a lower sensitivity to light than the first photoelectric conversion units; the first photoelectric conversion unit and the second photoelectric conversion unit are located on a first plane parallel to a light incident surface of the substrate, a first member overlapping the first photoelectric conversion unit and a second member overlapping the second photoelectric conversion unit are positioned adjacent to each other on a second plane parallel to the light incident surface of the substrate; the first member and the second member are both covered with the color filter, The refractive index of the first member is higher than the refractive index of the second member, A photoelectric conversion device characterized in that, when viewed in a planar view, at least a portion of one of the multiple first photoelectric conversion units and at least a portion of the other first photoelectric conversion unit are arranged so as to overlap the first member.

6. 6. The photoelectric conversion device according to claim 5, wherein the distance from the first plane to the second plane is 300 nm or less.

7. The first member has a lower surface and an upper surface, a first distance between the lower surface and the first photoelectric conversion unit is smaller than a second distance between the upper surface and the first photoelectric conversion unit; a portion of the first photoelectric conversion unit of the one of the first photoelectric conversion units and a portion of the first photoelectric conversion unit of the other of the first photoelectric conversion units are arranged to overlap with the lower surface in a plan view; A photoelectric conversion device according to any one of claims 1 to 3, claim 5 and claim 6, characterized in that, in a planar view, the entirety of one of the first photoelectric conversion units and the entirety of the other of the first photoelectric conversion units are arranged so as to overlap the upper surface.

8. the second photoelectric conversion unit is disposed so as not to overlap the lower surface in a plan view; The photoelectric conversion device according to claim 7 , wherein at least a portion of the second photoelectric conversion portion is arranged to overlap the upper surface in a plan view.

9. the pixel includes one or more microlenses; 9. The photoelectric conversion device according to claim 1, wherein the first photoelectric conversion section, the second photoelectric conversion section, the first member, and the second member are disposed below the microlens.

10. 10. The photoelectric conversion device according to claim 1, wherein one of the first photoelectric conversion unit and the second photoelectric conversion unit is located on the outer edge of a pixel and the other is located in the center of the pixel, forming a nested structure.

11. 11. The photoelectric conversion device according to claim 1, wherein the first member and the second member contain two or more of Si, N, O, H, C, and S.

12. 12. The photoelectric conversion device according to claim 1, wherein the pixel is configured by stacking a plurality of semiconductor substrates including a first substrate having the first photoelectric conversion unit and the second photoelectric conversion unit, and a circuit substrate having a circuit.

13. 13. The photoelectric conversion device according to claim 1, wherein the pixel is a back-illuminated CMOS sensor.

14. The photoelectric conversion device according to any one of claims 1 to 13, a processing device that processes a signal output from the photoelectric conversion device; An imaging system comprising:

15. 15. A digital camera comprising: the imaging system according to claim 14; and a lens for forming a subject image on the photoelectric conversion device of the imaging system.

16. A mobile object, The photoelectric conversion device according to claim 1 , a processing device that processes a signal output from the photoelectric conversion device; and a control means for controlling the moving body based on a result of the processing.

17. A method for producing a photoelectric conversion device having a color filter, comprising the steps of: forming a plurality of first semiconductor regions and a second semiconductor region that constitute a photoelectric conversion unit; forming a first member disposed between a light incident surface side of the first semiconductor region and a part of a color filter, and a second member disposed between a light incident surface side of the second semiconductor region and a part of a color filter, The first member and the second member are adjacent to each other, The refractive index of the first member and the refractive index of the second member are different, A method for manufacturing a photoelectric conversion device, characterized in that, in a planar view, at least a portion of one of the plurality of first semiconductor regions and at least a portion of the other first semiconductor region are arranged to overlap with the first member.

18. The step of forming the second member includes: The method for manufacturing a photoelectric conversion device according to claim 17 , comprising the steps of: removing a portion of the first member; and arranging a material that will become the second member in a groove portion formed by the removal.

19. The first member has a lower surface and an upper surface, a first distance between the lower surface and the first semiconductor region is smaller than a second distance between the upper surface and the first semiconductor region; a portion of the one first semiconductor region and a portion of the other first semiconductor region are arranged to overlap with the lower surface in a plan view; 19. The method for manufacturing a photoelectric conversion device according to claim 17 or 18, characterized in that, in a planar view, the entire one of the first semiconductor regions and the entire other of the first semiconductor regions are arranged to overlap the upper surface.

20. the second semiconductor region is arranged so as not to overlap the lower surface in a plan view; The method for manufacturing a photoelectric conversion device according to claim 19 , wherein at least a portion of the second semiconductor region is disposed so as to overlap the upper surface in a plan view.

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