Light detection device

Abstract

The present disclosure relates to a light detection device that makes it possible to suppress heterogeneity of pixel characteristics between adjacent pixels separately formed by injecting implant impurities. The light detection device comprises a separation structure that is formed on a substrate and in which adjacent first and second pixels are separated. The first and the second pixels are disposed on the substrate such that the surface of the substrate and a crystal plane constituting the substrate are aligned in a mutually parallel direction. The present disclosure can be applied to a light detection device.

Description

Photodetection device

[0001] The present disclosure relates to a photodetection device, and particularly to a photodetection device configured to suppress non-uniformity in pixel characteristics between adjacent pixels formed separately by implant impurity implantation.

[0002] In a pixel structure of a photodetection device such as an image sensor, a separation structure for separating pixels is sometimes formed by implanting implant impurities between pixels.

[0003] This separation structure needs to be formed by allowing implant impurities to penetrate from the surface of a wafer on which the pixel structure is formed to a sufficient depth.

[0004] Accordingly, a technique has been proposed in which implant impurities are implanted within ±0.2° relative to the normal direction with respect to the crystal plane of a silicon substrate forming a wafer, so that the implant impurities are implanted to a sufficient depth from the wafer surface (see, for example, Patent Document 1).

[0005] Japanese Patent Laid-Open No. 2005-191311

[0006] Incidentally, it is known that a wafer on which a pixel structure of a photodetection device such as an image sensor is formed is cut out from an ingot in a state inclined by about 0.35° relative to the normal direction of the crystal plane in order to promote epitaxial growth.

[0007] However, when a wafer is cut out in such a state inclined by about 0.35° relative to the normal direction of the crystal plane, application of the invention described in the aforementioned Patent Document 1 results in implant impurities implanted for forming the separation structure diffusing along the inclination of the crystal plane in the normal direction.

[0008] As a result, the implant impurities implanted for forming the separation structure may diffuse asymmetrically between adjacent pixels, which may lead to non-uniform pixel characteristics between adjacent pixels.

[0009] The present disclosure has been made in view of such circumstances, and particularly aims to suppress non-uniformity in pixel characteristics between adjacent pixels formed separately by implant impurity implantation.

[0010] One aspect of the present disclosure is a photodetector comprising a separation structure formed on a substrate for separating a first pixel and a second pixel that are adjacent to each other, wherein the first pixel and the second pixel are arranged on the substrate in a direction parallel to the surface of the substrate and the crystal plane constituting the substrate.

[0011] In one aspect of this disclosure, a separation structure is provided on a substrate for separating a first pixel and a second pixel that are adjacent to each other, and the first pixel and the second pixel are arranged on the substrate in a direction parallel to the surface of the substrate and the crystal plane constituting the substrate.

[0012] This is a diagram illustrating the wafer manufacturing process. This is a diagram illustrating the wafer cutting angle. This is a diagram illustrating an example where the pixel characteristics of the L pixel and R pixel in an image plane phase difference pixel differ. This is a diagram illustrating an example where the pixel characteristics of the L pixel and R pixel in an image plane phase difference pixel differ. This is a diagram illustrating an overview of the present disclosure. This is a diagram illustrating an example configuration of the photodetector device of the present disclosure. This is a diagram illustrating an example of the pixel circuit of the photodetector device of Figure 6. This is a side cross-sectional view of the pixel structure of Figure 6. This is a diagram illustrating an example configuration of the first embodiment of the image plane phase difference pixel of the present disclosure. This is a diagram illustrating a first modification of the first embodiment. This is a diagram illustrating a second modification of the first embodiment. This is a diagram illustrating a third modification of the first embodiment. This is a diagram illustrating a fourth modification of the first embodiment. This is a diagram illustrating an example configuration of the second embodiment of the image plane phase difference pixel of the present disclosure. This is a block diagram illustrating an example configuration of an imaging device as an electronic device to which the photodetector device of the present disclosure is applied. This is a diagram illustrating an example of use of the photodetector device to which the technology of the present disclosure is applied.

[0013] Preferred embodiments of this disclosure will be described in detail below with reference to the attached drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant descriptions will be omitted.

[0014] The following describes embodiments for implementing this technology. The description will proceed in the following order: 1. Overview of the Disclosure 2. First Embodiment 2-1. First Modification of the First Embodiment 2-2. Second Modification of the First Embodiment 2-3. Third Modification of the First Embodiment 2-4. Fourth Modification of the First Embodiment 3. Second Embodiment 4. Application Examples to Electronic Devices 5. Example of Use of a Solid State Imaging Device

[0015] <<1. Overview of this Disclosure>> <Wafer Cutting Angle> This disclosure particularly aims to suppress heterogeneity in pixel characteristics between adjacent pixels that are separated and formed by the injection of implantable impurities. First, we will explain the principle by which heterogeneity in pixel characteristics occurs between adjacent pixels that are separated and formed by the injection of implantable impurities.

[0016] The photodetector is manufactured by forming multiple units on a silicon (Si) wafer and then dicing them.

[0017] The wafer on which this photodetector is formed is created by slicing a cylindrical crystalline mass called an ingot, which is made of a single crystal of silicon (Si), at a predetermined angle with respect to the cylindrical axis (the direction normal to the crystal plane).

[0018] More specifically, as shown in the left part of Figure 1, first, in the first step St1, a Si single crystal 31 is formed, which is a cylindrical crystalline mass made of silicon (Si) single crystals called an ingot.

[0019] Next, in the second step St2, the Si single crystal 31 is cut perpendicular to the cylindrical axis at predetermined intervals to form blocks 32.

[0020] Furthermore, in a third step St3, the outer diameter of the block 32 is polished (outer diameter polishing), thereby forming a nearly perfectly cylindrical block 32'.

[0021] Then, in the fourth step St4, the outer diameter polished block 32' is sliced ​​at a predetermined angle with respect to the central axis on the cylinder (crystal direction = normal direction to the crystal plane), thereby cutting out the wafer 33.

[0022] In this fourth step St4, when the wafer 33 is cut from the block 32', in order to promote epitaxial growth in the subsequent process of forming the photodetector, the wafer 33 is sliced ​​as shown in Figure 2, with its normal direction Nw to its own disc-shaped surface tilted by about 0.35° with respect to the cylindrical central axis direction (normal direction to the crystal plane of a single Si crystal) Nsi, which is the crystal direction in the block 32'.

[0023] In the following, the cutting angle, which is the difference between the direction Nw normal to the surface of the wafer 33 and the crystal direction (the axis direction of the central axis of the cylinder) Nsi when the wafer 33 is cut from block 32', will also be simply referred to as the off-angle Aoff (cutting angle = Aoff). Furthermore, the direction in which the off-angle Aoff is projected onto the disk surface of the wafer 33 will also be referred to as the off-angle direction DAoff.

[0024] Furthermore, a chip 41 constituting the photodetector is formed on the wafer (substrate) 33, as shown in the lower left of Figure 3.

[0025] Here, for example, consider the case where, as shown in the lower left and upper left of Figure 3, the L pixels 51L and R pixels 51R constituting the image plane phase difference pixels are formed sequentially from left to right in the off-angle direction DAoff on the chip 41 on which the light detection device is formed.

[0026] Furthermore, in the upper left of Figure 3, a floating diffusion layer (FD) 52 is formed in the upper center of the figure, which is shared by the L pixels 51L and R pixels 51R that constitute the image plane phase difference pixels, and their respective ground potentials (GND) 53L and 53R are formed at the lower left and right ends of the figure.

[0027] In this case, an implantable impurity is injected from the front to the back of the paper in the figure at an intermediate position between the L pixel 51L and the R pixel 51R, thereby forming a separation structure 54 between the pixels.

[0028] Here, since the off-angle Aoff (cutting angle) of wafer 33 is set to 0.35°, as shown in the upper center of Figure 3, the crystal plane Fc of wafer 33 is not horizontal, but is formed tilted to the lower right side of the figure.

[0029] Thus, the crystal plane Fc of the wafer 33 is formed with an off-angle Aoff (cutting angle) of 0.35°, as shown in the upper center of Figure 3.

[0030] The implantable impurities for forming the separation structure 54 are injected from direction Dtr, which is perpendicular to the crystal plane Fc, at a cutting angle of 0.35°, so that they penetrate from the surface of the wafer 33 to a deeper position and form the separation structure 54.

[0031] Furthermore, the upper center of Figure 3 is a cross-sectional view of AA' in the upper left of Figure 3. Also, the direction Dtr, which is perpendicular to the crystal plane Fc in accordance with the cutting angle of 0.35°, is also referred to as the TrueZero direction.

[0032] In this way, when implantable impurities are injected onto the surface of the wafer 33 from a direction Dtr corresponding to an off-angle Aoff of 0.35°, they penetrate to a deeper location without widespread diffusion, as shown in the upper right of Figure 3, thereby forming a separation structure 54tr.

[0033] Furthermore, the upper right portion of Figure 3 represents an image of the outer diameter structure of the separation structure 54 formed by the injection of implant impurities from direction Dtr, as viewed from the direction shown in the upper center of Figure 3. Here, the separation structure 54 formed by injection from direction Dtr is also referred to as separation structure 54tr to distinguish it from those formed by other methods.

[0034] However, as shown in the upper right of Figure 3, in accordance with the 0.35° off-angle Aoff, the implanted impurities injected from direction Dtr diffuse while shifting to the left along the crystal structure. As a result, the separation structure 54tr formed by the implanted impurities is formed with a shape that is shifted to the left in the figure as it is deeper than the central position of the L pixel 51L and R pixel 51R shown by the dotted line in the figure. Consequently, as shown in the lower right of Figure 3, the potential of the L pixel 51L is formed to be higher than the potential of the R pixel 51R, resulting in uneven pixel characteristics between the L pixel 51L and the R pixel 51R.

[0035] Furthermore, the lower right of Figure 3 shows the potential distributions of the L pixel 51L and R pixel 51R, respectively, as dotted and solid lines, with the vertical axis representing potential and the horizontal axis representing the depth from the surface of the wafer 33 (Si Depth).

[0036] In other words, the pixel characteristics of the L pixel 51L and R pixel 51R, which are formed adjacent to each other with the separation structure 54tr in between, are not homogeneous.

[0037] Furthermore, as shown in the upper center of Figure 3, the separation structure 54tr shifts significantly to the left as it is located deeper from the surface of the wafer 33.

[0038] Therefore, it is conceivable that by not adjusting the injection angle of the implant impurities to the 0.35° off-angle Aoff, that is, by injecting them perpendicular to the surface of the wafer 33 rather than perpendicular to the crystal plane Fc, penetration in the depth direction is suppressed while diffusion is more widespread in the horizontal direction, thereby suppressing the imbalance in the potential distribution of the L pixels 51L and R pixels 51R formed adjacent to each other across the separation structure 54, and improving the heterogeneity of the pixel characteristics.

[0039] Figure 4 shows the implant impurity injection angle set perpendicular to the surface of the wafer 33.

[0040] Furthermore, the upper left part and upper center part of FIG. 4 are a top view and an AA' cross-sectional view of an image plane phase difference pixel when the implantation angle of the implant impurity is set to the direction Dtil perpendicular to the surface of the wafer 33. In addition, the direction Dtr, which is perpendicular to the surface of the wafer 33, is also referred to as the TiltZero direction.

[0041] As described above, by implanting the implant impurity from the direction Dtil which is perpendicular to the surface of the wafer 33, as shown in the upper right part of FIG. 4, penetration to a deeper position is suppressed compared to the case where the implant impurity is implanted from the direction Dtr, and by being diffused wider in the horizontal direction by that amount, the isolation structure 54til is formed.

[0042] Furthermore, the upper right part of FIG. 4 shows an image of the outer diameter structure of the isolation structure 54til formed by implanting implant impurities from the direction Dtil when viewed from the direction shown as the second one from the left in the upper stage of FIG. 4. In addition, the dotted line shows the isolation structure 54tr of FIG. 3 for comparison.

[0043] However, as shown in the upper right part of FIG. 4, although the shift of the isolation structure 54til toward the L pixel 51L side is somewhat suppressed compared with the isolation structure 54tr, the isolation structure 54til is formed in a shape shifted to the left side in the figure with respect to the center position of the L pixel 51L and the R pixel 51R indicated by the dotted line. Therefore, as shown in the lower right part of FIG. 4, the potential of the L pixel 51L is formed higher than the potential of the R pixel 51R.

[0044] Furthermore, in the lower right part of FIG. 4, when the vertical axis represents potential and the horizontal axis represents depth from the surface of the wafer 33 (Si Depth), the respective potential distributions of the L pixel 51L and the R pixel 51R are represented by dotted and solid line graphs. In addition, the lower center part of FIG. 4 shows, for comparison, the respective potential distributions of the L pixel 51L and the R pixel 51R when implant impurities are implanted from the TrueZero direction.

[0045] That is, the pixel characteristics of the L pixel 51L and the R pixel 51R, which are adjacently formed with the isolation structure 54til interposed therebetween, also become non-uniform.

[0046] Therefore, in the present disclosure, as shown in the lower left part and upper left part of FIG. 5, on a chip 41 constituting the photodetection device, the L pixel 51L and R pixel 51R that constitute an image plane phase difference pixel are formed side by side in a direction perpendicular to the off-angle direction DAoff. In other words, the L pixel 51L and R pixel 51R constituting the image plane phase difference pixel are arranged in a direction perpendicular to the off-angle direction DAoff, which is a direction with no inclination of the crystal plane on the surface of the wafer 33, that is, a direction parallel to the crystal plane constituting the wafer 33 on the surface of the wafer 33.

[0047] Accordingly, as shown in the lower left part and upper left part of FIG. 5, by implanting implanted impurities in the off-angle direction DAoff (TrueZero direction) into the intermediate position between the L pixel 51L and R pixel 51R constituting the image plane phase difference pixel, even if the isolation structure 54' is formed inclined in the left-right direction in the figure (the direction perpendicular to the isolation direction of the L pixel 51L and R pixel 51R), it is not formed inclined in the up-down direction in the figure. That is, as shown in the upper right part and upper central part of FIG. 5, the implanted impurities are uniformly diffused and distributed at the intermediate position between the L pixel 51L and R pixel 51R, so that the isolation structure 54' is formed at the intermediate position between the L pixel 51L and R pixel 51R.

[0048] As a result, as shown in the lower right part of FIG. 5, non-uniformity in the potential distribution of the L pixel 51L and R pixel 51R that are adjacently formed with the isolation structure 54' interposed therebetween is suppressed, making it possible to suppress non-uniformity in pixel characteristics between the two pixels. Note that in the lower right part of FIG. 5, the potential distributions of the L pixel 51L and R pixel 51R are represented by a dotted line graph and a solid line graph, respectively. Since the two graphs substantially coincide with each other, the diagram is expressed as if only the solid line graph is shown.

[0049] <<2. First Embodiment>> Next, a configuration example of the photodetection device of the present disclosure will be described with reference to FIG. 6.

[0050] The photodetector 101 in Figure 6 consists of a pixel region (so-called imaging region) 103 in which multiple photoelectric conversion elements are arranged regularly in two dimensions on a semiconductor substrate 102, for example, a silicon substrate, and a peripheral circuit section.

[0051] Pixel 113 is composed of, for example, a photodiode, which acts as a photoelectric conversion element, and a plurality of pixel transistors (so-called MOS transistors). The plurality of pixel transistors are, for example, a transfer transistor, a capacitive switching transistor, a reset transistor, an amplification transistor, and a selection transistor. Pixel 113 can also be a shared pixel structure. This shared pixel structure is composed of a single floating diffusion region shared by a plurality of photodiodes and a plurality of transfer transistors, and one other pixel transistor shared by each of these regions.

[0052] The peripheral circuit section consists of a vertical drive circuit 104, a column signal processing circuit 105, a horizontal drive circuit 106, an output circuit 107, and a control circuit 108.

[0053] The control circuit 108 receives an input clock and data that commands the operating mode, and outputs data such as internal information of the light detection device 101. Specifically, the control circuit 108 generates clock signals and control signals that serve as the reference for the operation of the vertical drive circuit 104, column signal processing circuit 105, and horizontal drive circuit 106, etc., based on the vertical synchronization signal, horizontal synchronization signal, and master clock. The control circuit 108 then inputs these signals to the vertical drive circuit 104, column signal processing circuit 105, and horizontal drive circuit 106, etc.

[0054] The vertical drive circuit 104 is configured, for example, by a shift register, and selects a pixel drive wiring 112, supplies pulses to the selected pixel drive wiring 112 to drive the pixels, and drives the pixels row by row. That is, the vertical drive circuit 104 sequentially selects and scans each pixel 113 of the pixel region 103 in the vertical direction row by row, and supplies a pixel signal based on the signal charge generated in accordance with the amount of light received in a photoelectric conversion element of each pixel 113, such as a photodiode, through a vertical signal line 109 to the column signal processing circuit 15.

[0055] The column signal processing circuit 105 is arranged for each pixel 113, for example, in each column, and performs signal processing such as noise reduction on the signal output from one row of pixels 113 for each pixel column. That is, the column signal processing circuit 105 performs signal processing such as CDS (Correlated Double Sampling) to remove fixed pattern noise specific to the pixels 113, signal amplification, and AD conversion. A horizontal selection switch (not shown) is provided at the output stage of the column signal processing circuit 105, connected to the horizontal signal line 110.

[0056] The horizontal drive circuit 106 is configured, for example, by a shift register, and sequentially outputs horizontal scanning pulses to select each of the column signal processing circuits 105 in order, causing each of the column signal processing circuits 105 to output a pixel signal to the horizontal signal line 110.

[0057] The output circuit 107 processes the signals supplied sequentially from each of the column signal processing circuits 105 through the horizontal signal line 110 and outputs them. For example, it may only perform buffering, or it may perform black level adjustment, column variation correction, and various digital signal processing. The input / output terminal 111 is used for exchanging signals with the outside.

[0058] <Example of Circuit Configuration of Light Detection Device> Next, an example of the circuit configuration of the pixel 113 constituting the light detection device 101 will be described with reference to Figure 7. Figure 7 is a circuit diagram showing an example of the circuit configuration of the pixel 113 of this disclosure.

[0059] The pixel 113 in Figure 7 comprises a photoelectric conversion unit (PD) 121, a transfer transistor (TRG) 122, a charge holding unit (FD) 123, a capacitance switching transistor (FDG) 124, an additional capacitance unit 125, a reset transistor (RST) 126, a power supply (VDD) that supplies power to the pixel 113, an amplification transistor (AMP) 127, and a selection transistor (SEL) 128.

[0060] The anode of the photoelectric conversion unit 121 is grounded, and its cathode is connected to the source of the transfer transistor 122. The drain of the transfer transistor 122 is connected via the charge retention unit 123 to the source of the reset transistor 126, the gate of the amplification transistor 127, and the source of the capacitance switching transistor 124. The drain of the capacitance switching transistor 124 is connected to one end of the additional capacitance unit 125. The other end of the additional capacitance unit 125 is grounded. The drain of the reset transistor 126 is connected to the power supply VDD. The drain of the amplification transistor 127 is connected to the power supply VDD, and its source is connected to the drain of the selection transistor 128. The source of the selection transistor 128 is connected to the signal line (VSL) 109.

[0061] The photoelectric conversion unit 121 performs photoelectric conversion of incident light and can be composed of a photodiode formed on a semiconductor substrate. The photoelectric conversion unit 121 performs photoelectric conversion of incident light during the exposure period and retains the charge generated by the photoelectric conversion.

[0062] The charge holding section 123 holds the charge generated by the photoelectric conversion section 121. The charge holding section 123 can be composed of a floating diffusion region (FD), which is a semiconductor region formed on a semiconductor substrate.

[0063] The transfer transistor 122 is responsible for transferring electric charge. The transfer transistor 122 transfers the charge generated by the photoelectric conversion of the photoelectric conversion unit 121 to the charge holding unit 123. The transfer transistor 122 transfers the charge by creating electrical conductivity between the photoelectric conversion unit 121 and the charge holding unit 123. The control signals of the transfer transistor 122 are transmitted via signal lines TRG.

[0064] An additional capacitance unit 125 is further connected to the charge holding unit 123 via a capacitance switching transistor 124. The capacitance switching transistor 124 is controlled to be on or off in accordance with the drive signal FDG, thereby switching the charge holding unit 123 and the additional capacitance unit 125 between an electrically connected state and an unconnected state.

[0065] As a result, when the drive signal FDG is supplied to the gate electrode constituting the capacitance switching transistor 124 and controlled to turn on, the potential directly beneath the capacitance switching transistor 124 deepens, and the charge holding unit 123 and the additional capacitance unit 125 become electrically connected.

[0066] On the other hand, if the gate electrode constituting the capacitance switching transistor 124 is not supplied with a drive signal FDG and is controlled to be off, the potential directly below the capacitance switching transistor 124 becomes shallower, and the charge holding unit 123 and the additional capacitance unit 125 become electrically disconnected (disconnected).

[0067] Therefore, by controlling the capacitance switching transistor 124 to be on or off by the drive signal FDG, it is possible to switch between a state in which the capacitance of the additional capacitance unit 125 is added to the capacitance of the charge holding unit 123, or a state in which it is not added, thereby switching the pixel sensitivity (switching the conversion efficiency).

[0068] In the example circuit configuration of pixel 113 in Figure 7, a configuration is shown in which a capacitance switching transistor 124 and an additional capacitance unit 125 are provided to enable switching of pixel sensitivity. However, if it is not necessary to switch the pixel sensitivity, the capacitance switching transistor 124 and the additional capacitance unit 125 may be omitted. Furthermore, in the following explanation, unless otherwise specified, it will be assumed that the configuration does not include the capacitance switching transistor 124 and the additional capacitance unit 125.

[0069] The reset transistor 126 resets the charge holding unit 123 (and, if the capacitance switching transistor 124 is on, also the additional capacitance unit 125). This reset is performed by conducting electricity between the charge holding unit 123 (and the additional capacitance unit 125) and the power supply VDD to discharge the charge from the charge holding unit 123 (and the additional capacitance unit 125). The control signal for the reset transistor 126 is transmitted via the signal line RST.

[0070] The amplification transistor 127 amplifies the voltage of the charge holding section 123 (and the additional capacitance section 125). The gate of the amplification transistor 127 is connected to the charge holding section 123 (and the additional capacitance section 125). Therefore, an image signal of a voltage corresponding to the charge held in the charge holding section 123 (and the additional capacitance section 125) is generated at the source of the amplification transistor 127. Furthermore, by conducting the selection transistor 128, this image signal can be output to the signal line (VSL) 109. The control signal of the selection transistor 128 is transmitted via the signal line SEL.

[0071] <Example of Pixel Physical Configuration> Next, with reference to Figure 8, the pixel structure, which is the physical configuration of the pixel 113, will be explained. Figure 8 shows a cross-sectional structure of two pixels 113 arranged horizontally. The right side of the figure represents a normal pixel 113, and the left side represents an image plane phase-difference pixel 113P in which the pixel 113 is separated into left and right sides.

[0072] The image plane phase-difference pixel 113P is configured such that the L pixel 113L on the left side of the figure and the R pixel 113R on the right side of the figure are separated by a separation structure 171. However, in terms of physical structure, the image plane phase-difference pixel 113P is the same as a normal pixel 113, except that the L pixel 113L and the R pixel 113R are formed when the pixel 113 is separated by the separation structure 171. Therefore, in the explanation of Figure 8, the image plane phase-difference pixel 113P, which consists of the L pixel 113L and the R pixel 113R, will also be explained as a normal pixel 113.

[0073] Each pixel 113 is composed of an OCL (On Chip Lens) 151, a CF (Color Filter) 152, a wall between CFs (Color Filters) 153, a planarization film 154, an inter-pixel wall 155, and a photoelectric conversion region 156.

[0074] The photoelectric conversion region 156 has a configuration corresponding to the photoelectric conversion unit 121 in Figure 7, and functions as a photodiode PD, generating a pixel signal corresponding to the amount of incident light.

[0075] The OCL 151 focuses the incident light from above in the figure and focuses it on the light-receiving surface of the photoelectric conversion region 156.

[0076] CF152 transmits only light in a predetermined wavelength range from the light transmitted through OCL151. For example, CF152 transmits light in a predetermined wavelength range such as RGB.

[0077] A planarization film 154 is formed at the boundary between the CF 152 and the photoelectric conversion region 156. In addition, inter-CF walls 153 are formed on the planarization film 154 between the CFs 152. Furthermore, inter-pixel walls 155 are formed between the photoelectric conversion regions 156.

[0078] With this configuration, in the pixel 113 on the right side of Figure 8, when incident light enters from the top surface of Figure 8, it is focused at the OCL 151, light of a predetermined wavelength band is transmitted at the CF 152, and the incident light enters the photoelectric conversion region 156 which functions as a photoelectric conversion unit 121, and a pixel signal corresponding to the amount of light is detected.

[0079] <Detailed Configuration of Image Plane Phase Difference Pixels> Next, with reference to Figure 9, the detailed configuration of the image plane phase difference pixel 113P will be described.

[0080] The image plane phase difference pixel 113P in Figure 9 has a so-called plug-in type pixel configuration. As shown in the lower left and upper left of Figure 9, on the photodetector 101 (corresponding to the chip 41 in Figure 5) formed in a chip shape on the wafer (substrate) 100 (corresponding to the wafer (substrate) 33 in Figure 5), the L pixels 113L and R pixels 113R (corresponding to the L pixels 51L and R pixels 51R in Figure 5, respectively) that constitute the image plane phase difference pixel 113P are formed sequentially from the top in the figure in a direction perpendicular to the off-angle direction DAoff direction.

[0081] As shown in the left part of Figure 9, the image plane phase difference pixels of this disclosure consist of an L pixel 113L on the upper side of the figure and an R pixel 113R on the lower side of the figure, with a separation structure 171 formed in the center between them.

[0082] More specifically, as shown in the left part of Figure 9, the image plane phase-difference pixel 113P is surrounded by an inter-pixel wall 155, and near the boundary between the L pixel 113L and the R pixel 113R on the lower side of the figure, protrusions 155a-1 and 155a-2 are formed protruding from the left and right inter-pixel walls 155, parallel to the off-angle direction DAoff, and in the figure, their respective tips face each other from the left and right directions. Note that the protrusions 155a all have the same configuration as the inter-pixel wall 155, but here they are referred to as protrusions 155a for distinction.

[0083] The separation structure 171 is formed across the space between the protrusions 155a-1 and 155a-2 so as to fill the gap 155b formed between the left and right protrusions 155a-1 and 155a-2 in the figure. With this configuration, the L pixel 113L and R pixel 113R that constitute one image plane phase difference pixel 113P are formed separately by the separation structure 171.

[0084] Furthermore, in the upper left of Figure 9, a floating diffusion layer (FD) 123 is formed in the middle left section of the figure, shared by the L pixels 113L and R pixels 113R that constitute the image plane phase difference pixels, and their respective ground potentials (GND) 161L and 161R are formed at the upper and lower right ends of the figure, respectively.

[0085] In this case, implant impurities are injected at an intermediate position between the L pixel 113L and the R pixel 113R, from the front to the back of the paper in the figure, for example, in the direction D which is the TrueZero direction. As a result, the diffusion of the implant impurities in the vertical direction in the figure is suppressed, and they penetrate more deeply in the direction of the back of the paper in the figure, forming a separation structure 171 between pixels.

[0086] In other words, although the wafer 100 has an off-angle Aoff (cutting angle) of 0.35°, when viewing the AA' cross section in the upper left of Figure 9 from the off-angle direction DAoff, as shown in the upper center of Figure 9, the crystal plane FC of the wafer 100 is horizontal. Therefore, the implanted impurities injected from the D direction have their diffusion in the vertical direction of the figure suppressed, and penetrate deeper in the direction towards the back of the paper to form a separation structure 171.

[0087] In this way, the L pixels 113L and R pixels 113R constituting the image plane phase difference pixels 113P are formed aligned perpendicular to the off-angle direction DAoff. As a result, implant impurities are injected from the surface of the wafer 100 from direction D, which is the TrueZero direction relative to the crystal plane FC, at a cutting angle of 0.35°. This suppresses diffusion in the vertical direction in the figure, preventing uneven diffusion in the region where the L pixels 113L and R pixels 113R are formed, and also allows penetration to reach deeper positions in the background direction in the figure, forming the separation structure 171.

[0088] The upper right portion of Figure 9 shows an image of the outer diameter structure of the separation structure 171 formed when implant impurities are injected from direction D, as seen in the AA' cross-section in the upper left portion.

[0089] As shown in the upper right of Figure 9, the separation structure 171 is formed at the central position of the L pixel 113L and R pixel 113R along an off-angle Aoff of 0.35°. As a result, as shown in the lower right of Figure 9, the potential of the L pixel 113L and the potential of the R pixel 113R are formed to be equal.

[0090] In the lower right of Figure 9, the potential distributions of the L pixel 113L and R pixel 113R are shown as dotted and solid lines, respectively, with the vertical axis representing potential and the horizontal axis representing the depth from the surface of the wafer 33 (Si Depth). Here, in the lower right of Figure 9, the potential distribution of the L pixel 113L is represented by a dotted line and the potential distribution of the R pixel 113R is represented by a solid line. However, since the potential distributions of the L pixel 113L and R pixel 113R are almost identical, only the potential distribution consisting of a single solid line is displayed in the lower right of Figure 9.

[0091] In other words, in the photodetector 101 of this disclosure, as shown in Figure 9, the image plane phase difference pixels 113P are formed such that L pixels 113L and R pixels 113R are arranged side by side in a direction perpendicular to the off-angle direction DAoff of the wafer 100. In other words, on the surface of the wafer 100, the L pixels 113L and R pixels 113R are formed side by side in a direction that is not tilted in the crystal plane constituting the wafer 100, that is, in a direction that is parallel to the crystal plane constituting the wafer 100 on the surface of the wafer 100.

[0092] As a result, implant impurities are injected in the direction D, which is the TrueZero direction, from an intermediate position between the L pixel 113L and the R pixel 113R. The injected implant impurities are then distributed almost evenly at the intermediate position between the L pixel 113L and the R pixel 113R, as shown in the upper right of Figure 9, forming a separation structure 171.

[0093] As a result, the non-uniformity of the pixel characteristics of the L pixels 113L and R pixels 113R, which are formed adjacent to each other with the separation structure 171 constituting the image plane phase difference pixel 113P, is suppressed.

[0094] In this example, we have used an image plane phase-difference pixel 113P, formed by the separation of an L pixel 113L and an R pixel 113R that function as a pair, as an example of a pixel equipped with a separation structure 171. However, it is not limited to image plane phase-difference pixels 113P as long as it has a structure that separates adjacent pixels. For example, even when a separation structure equivalent to the separation structure 171 formed by injecting implantable impurities is used as the inter-pixel structure of a normal pixel, the same method can be used to suppress the inhomogeneity of pixel characteristics between adjacent pixels.

[0095] Furthermore, in this example, we have described an example in which implant impurities are injected in the D direction, which is the TrueZero direction, from an intermediate position between the L pixel 113L and the R pixel 113R. However, the implant impurities may also be injected from the TiltZero direction, which is perpendicular to the surface of the wafer 100, at an intermediate position between the L pixel 113L and the R pixel 113R.

[0096] In other words, even if the implanted impurities are injected from the TiltZero direction, which is perpendicular to the surface of the wafer 100, at an intermediate position between the L pixels 113L and R pixels 113R, the unbalanced diffusion in the vertical direction in the upper left of Figure 9 is suppressed, making it possible to suppress the inhomogeneity of the pixel characteristics between adjacent L pixels 113L and R pixels 113R.

[0097] However, when implant impurities are injected from the TiltZero direction, which is perpendicular to the surface of the wafer 100, at an intermediate position between the L pixel 113L and the R pixel 113R, the degree of vertical diffusion in the upper left of Figure 9 and the depth of penetration towards the back of the paper will be inferior to when they are injected from the D direction, which is the TrueZero direction. Therefore, when forming the separation structure 171, it is desirable that the implant impurities be injected from the D direction, which is the TrueZero direction.

[0098] <<2-1. First Modification of the First Embodiment>> In the above, we have described an example in which, when forming one image plane phase difference pixel 113P, one separation structure 171 is formed across the space between the protrusions 155a-1 and 155a-2 so as to fill a gap 155b formed between the protrusions 155a-1 and 155a-2.

[0099] However, a single protrusion 155a may be formed on a single image plane phase difference pixel 113P, a gap 155b may be formed near the opposing inter-pixel wall 155, and a separation structure 171 may be formed to fill the gap 155b, spanning the protrusion 155a and the inter-pixel wall 155.

[0100] Furthermore, two image plane phase difference pixels 113P may be arranged so that the gaps 155b are adjacent to each other, and a single separation structure 171 may be formed spanning the two gaps 155b between adjacent image plane phase difference pixels 113P.

[0101] In other words, Figure 10 shows an example in which two image plane phase difference pixels 113P-1 and 113P-2 are formed adjacent to each other vertically, the off-angle direction DAoff is set in the upward direction in the figure, and L pixels 113L-1 and 113L-2 are formed on the left side perpendicular to the off-angle direction DAoff, and R pixels 113R-1 and 113R-2 are formed on the right side.

[0102] In Figure 10, a floating diffusion layer (FD) 123-1 shared by the L pixel 113L-1 and the R pixel 113R-1 is formed in the upper center of the image plane phase difference pixel 113P-1, and a floating diffusion layer (FD) 123-2 shared by the L pixel 113L-2 and the R pixel 113R-2 is formed in the lower center of the image plane phase difference pixel 113P-2.

[0103] Furthermore, in Figure 10, a ground potential (GND) 161L shared by L pixels 113L-1 and L pixels 113L-2 is provided on the left side of the center, and a ground potential (GND) 161R shared by R pixels 113R-1 and R pixels 113R-2 is provided on the right side of the center.

[0104] Furthermore, in the image plane phase difference pixel 113P-1, a protrusion 155a'-1 extending from the interpixel wall 155 at the top of the figure is formed opposite to the interpixel wall 155A that divides the image plane phase difference pixels 113P-1 and 113P-2, such that a gap 155b'-1 is formed between them.

[0105] On the other hand, in the image plane phase difference pixel 113P-2, the protrusion 155a'-2 is formed opposite to the interpixel wall 155 at the bottom of the figure, such that an interpixel wall 155A that divides the image plane phase difference pixels 113P-1 and 113P-2 is formed, and a gap 155b'-2 is formed.

[0106] In other words, the protrusions 155a'-1 and 155a'-2 are formed opposite each other from the interpixel wall 155 at the upper and lower ends in the figure, with the interpixel wall 155A in between, and gaps 155b'-1 and 155b'-2 are formed adjacent to each other at their respective ends, with the interpixel wall 155A in between.

[0107] Furthermore, the separation structure 171A is formed collectively across the interpixel wall 155A to fill the gaps 155b'-1 and 155b'-2. With the formation of the separation structure 171A in this way, the L pixel 113L-1 and R pixel 113R-1, and the L pixel 113L-2 and R pixel 113R-2 of the image plane phase difference pixels 113P-1 and 113P-2 are formed separately.

[0108] Thus, in the image plane phase-difference pixel 113P, the protrusion 155a' may be formed as a single protrusion extending from one of the inter-pixel walls 155, thereby creating a gap 155b' near the other inter-pixel wall 155.

[0109] Furthermore, as shown in Figure 10, between image plane phase difference pixels 113P-1 and 113P-2 adjacent to each other in the off-angle direction DAoff, gaps 155b'-1 and 155'-2 may be formed adjacent to each other with the interpixel wall 155A in between.

[0110] Furthermore, as shown in Figure 10, if gaps 155b'-1 and 155'-2 are formed adjacent to each other between image plane phase difference pixels 113P-1 and 113P-2 that are adjacent in the off-angle direction DAoff, with the interpixel wall 155A in between, a separation structure 171' may be formed across the interpixel wall 155A so as to fill the gaps 155b'-1 and 155'-2, thereby separating the L pixels 113L-1 and R pixels 113R-1, and the L pixels 113L-2 and R pixels 113R-2 of the image plane phase difference pixels 113P-1 and 113P-2, respectively.

[0111] In the configuration shown in Figure 10, the L pixels 113L-1 and R pixels 113R-1, and the L pixels 113L-2 and R pixels 113R-2 of the image plane phase difference pixels 113P-1 and 113P-2 are each formed perpendicular to the off-angle direction DAoff. Therefore, the separation structure 171A is formed by injecting implantable impurities in the TrueZero direction along the off-angle direction DAoff. As a result, the L pixels 113L-1 and R pixels 113R-1, and the L pixels 113L-2 and R pixels 113R-2 can suppress inhomogeneity of the pixel characteristics.

[0112] <<2-2. Second Modification of the First Embodiment>> In the above, we have described an example in which the L pixel 113L-1 and R pixel 113R-1 of the image plane phase difference pixel 113P-1 share a floating diffusion layer (FD) 123-1, the L pixel 113L-2 and R pixel 113R-2 of the image plane phase difference pixel 113P-2 share a floating diffusion layer (FD) 123-2, the L pixels 113L-1 and 113L'-2 share a ground potential (GND) 161L, and the R pixels 113R-1 and 113R'-2 share a ground potential (GND) 161R.

[0113] However, the floating diffusion layer (FD) 123 and the ground potential (GND) 161 may be provided by the L pixel 113L and R pixel 113R of the image plane phase difference pixels 113P, respectively. In this case, if the image plane phase difference pixels 113P are adjacent, the floating diffusion layer (FD) 123 and the ground potential (GND) 161 may be adjacent to each other.

[0114] Figure 11 shows an example configuration of an image plane phase difference pixel 113P' in which the L pixel 113L and R pixel 113R of the image plane phase difference pixel 113P' are each equipped with a floating diffusion layer (FD) 123 and a ground potential (GND) 161, and furthermore, when adjacent, the floating diffusion layer (FD) 123 and the ground potential (GND) 161 are adjacent to each other.

[0115] Figure 11 shows an example in which two image plane phase difference pixels 113P'-1 and 113P'-2 are formed vertically, with the off-angle direction DAoff set in the upward direction in the figure, and L pixels 113L-1 and R pixels 113R-1, and L pixels 113L-2 and R pixels 113R-2 are formed from left to right perpendicular to the off-angle direction DAoff. Furthermore, L pixels 113L-1 and R pixels 113R-1, and L pixels 113L-2 and R pixels 113R-2 each independently have a floating diffusion layer (FD) 123 and a ground potential (GND) 161, and the floating diffusion layer (FD) 123 and ground potential (GND) 161 are formed adjacent to each other between adjacent pixels.

[0116] Specifically, L-pixel 113L-1 is equipped with a floating diffusion layer (FD) 123L-1 and a ground potential (GND) 161L-1, and L-pixel 113L-2 is equipped with a floating diffusion layer (FD) 123L-2 and a ground potential (GND) 161L-2.

[0117] Furthermore, the R pixel 113R-1 is equipped with a floating diffusion layer (FD) 123R-1 and a ground potential (GND) 161R-1, and the R pixel 113R-2 is equipped with a floating diffusion layer (FD) 123R-2 and a ground potential (GND) 161L-2.

[0118] Furthermore, the floating diffusion layer (FD) 123L-1 and the floating diffusion layer (FD) 123R-1 are formed adjacent to each other with a protrusion 155a''-1-1 in between, and the floating diffusion layer (FD) 123L-2 and the floating diffusion layer (FD) 123R-2 are formed adjacent to each other with a protrusion 155a''-1-2 in between.

[0119] Furthermore, ground potential (GND) 161L-1 and ground potential (GND) 161L-2 are formed adjacent to each other, separated by an interpixel wall 155A' which forms the boundary between image plane phase difference pixels 113P'-1 and 113P'-2. Ground potential (GND) 161R-1 and ground potential (GND) 161R-2 are formed adjacent to each other, separated by an interpixel wall 155A' which forms the boundary between image plane phase difference pixels 113P'-1 and 113P'-2.

[0120] In Figure 11, the configuration of two image plane phase difference pixels 113P'-1 and 113P'-2 is shown. However, if similar configurations are arranged adjacent to each other in the vertical and horizontal directions, the floating diffusion layer (FD) 123 and ground potential (GND) 161 will also be adjacent to each other between adjacent image plane phase difference pixels 113P' in each case.

[0121] Furthermore, in the configuration shown in Figure 11, a protrusion 155a''-1-1 is formed extending from the interpixel wall 155 at the upper end of the figure to the vicinity of the center position of the image plane phase difference pixel 113P'-1, and a protrusion 155a''-1-2 is formed extending from the interpixel wall 155A' to the vicinity of the center position of the image plane phase difference pixel 113P'-1. In addition, a gap 155b''-1 is formed between the protrusions 155a''-1-1 and 155a''-2-1, and a separation structure 171B-1 is formed to fill the gap 155b''-1. That is, the L pixel 113L-1 and the R pixel 113R-1 are separated and formed by the separation structure 171B-1.

[0122] Similarly, a protrusion 155a''-1-2 is formed extending from the interpixel wall 155 at the lower end of the figure to the vicinity of the center position of the image plane phase difference pixel 113P'-2, and a protrusion 155a''-2-2 is formed extending from the interpixel wall 155A' to the vicinity of the center position of the image plane phase difference pixel 113P'-2. In addition, a gap 155b''-2 is formed between the protrusions 155a''-1-2 and 155a''-2-2, and a separation structure 171B-2 is formed to fill the gap 155b''-2. That is, the L pixel 113L-1 and the R pixel 113R-1 are separated and formed by the separation structure 171B-2.

[0123] In the configuration shown in Figure 11, the L pixels 113L-1 and R pixels 113R-1, and the L pixels 113L-2 and R pixels 113R-2 of the image plane phase difference pixels 113P'-1 and 113P'-2 are each formed perpendicular to the off-angle direction DAoff. Therefore, the separation structures 171B-1 and 171B-2 are formed by injecting implantable impurities in the TrueZero direction (direction D in the figure) along the off-angle direction DAoff. As a result, the L pixels 113L-1 and R pixels 113R-1, and the L pixels 113L-2 and R pixels 113R-2 can suppress inhomogeneity of pixel characteristics between adjacent pixels.

[0124] <<2-3. Third Modification of the First Embodiment>> In the above, an example has been described in which the image plane phase difference pixels 113P'-1 and 113P'-2 are arranged vertically, and separation structures 171B-1 and 171B-2 are formed on each of them. However, the separation structures 171B-1 and 171B-2 may be integrated into a single structure.

[0125] Figure 12 shows an example in which image plane phase difference pixels 113P'-1 and 113P'-2 are arranged vertically, and the separation structures 171B-1 and 171B-2 are integrated to form a separation structure 171C.

[0126] In addition, Figure 12 is identical to the configuration in Figure 11, except that the separation structures 171B-1 and 171B-2 are replaced by separation structure 171C, so its explanation is omitted.

[0127] In other words, in Figure 12, separation structure 171C is formed in place of separation structures 171B-1 and 171B-2.

[0128] More specifically, the separation structure 171C is formed to fill both the gap 155b''-1 between the protrusions 155a''-1-1 and 155a''-2-1, and the gap 155b''-2 between the protrusions 155a''-1-2 and 155a''-2-2, by extending collectively from the lower end of the protrusion 155a''-1-1 in the figure to the upper end of the protrusion 155a''-2-1, the interpixel wall 155A' protrusion 155a''-2-2, and the upper end of the protrusion 155a''-1-2 in the figure.

[0129] In the configuration shown in Figure 12, the L pixels 113L-1 and R pixels 113R-1, and the L pixels 113L-2 and R pixels 113R-2 of the image plane phase difference pixels 113P'-1 and 113P'-2 are each formed perpendicular to the off-angle direction DAoff. Therefore, the separation structure 171C is formed by injecting implantable impurities in the TrueZero direction (direction D in the figure) along the off-angle direction DAoff. As a result, the L pixels 113L-1 and R pixels 113R-1, and the L pixels 113L-2 and R pixels 113R-2 can suppress the inhomogeneity of pixel characteristics between adjacent pixels.

[0130] <<2-4. Fourth Modification of the First Embodiment>> In the above, we have described a configuration in which two image plane phase difference pixels 113P'-1 and 113P'-2 are formed vertically, and the L pixel 113L-1 and R pixel 113R-1, and the L pixel 113L-2 and R pixel 113R-2 each share a floating diffusion layer (FD) 123 and ground potential (GND) 161, or each has its own floating diffusion layer (FD) 123 and ground potential (GND) 161.

[0131] However, the L pixel 113L-1 and the R pixel 113R-1, and the L pixel 113L-2 and the R pixel 113R-2 may share one floating diffusion layer (FD) 123.

[0132] Figure 13 shows an example in which L pixel 113L-1 and R pixel 113R-1, and L pixel 113L-2 and R pixel 113R-2 share one floating diffusion layer (FD) 123D.

[0133] In Figure 13, a floating diffusion layer (FD) 123D is formed in the central portions of L pixel 113L-1 and R pixel 113R-1, and L pixel 113L-2 and R pixel 113R-2.

[0134] Furthermore, L pixels 113L-1 and R pixels 113R-1, and L pixels 113L-2 and R pixels 113R-2 are each provided with ground potentials (GND) 161L-11 and 161R-11, and ground potentials (GND) 161L-12 and 161R-12 at the corners of the interpixel wall 155.

[0135] Furthermore, a protrusion 155a''''-1 is formed extending from the center of the interpixel wall 155 at the upper end of Figure 13 to the vicinity of the floating diffusion layer (FD). Also, a protrusion 155a''''-2 is formed extending from the center of the interpixel wall 155 at the right end of Figure 13 to the vicinity of the floating diffusion layer (FD). Furthermore, a protrusion 155a''''-3 is formed extending from the center of the interpixel wall 155 at the lower end of Figure 13 to the vicinity of the floating diffusion layer (FD). Also, a protrusion 155a''''-4 is formed extending from the center of the interpixel wall 155 at the left end of Figure 13 to the vicinity of the floating diffusion layer (FD).

[0136] Furthermore, a gap 155b'''' is formed near the floating diffusion layer (FD) which is the tip portion of the protrusions 155a''''-1 to 155a''''-4, and a separation structure 171D is formed to fill the gap 155b'''' from the tip portion of the protrusions 155a''''-1 to 155a''''-4.

[0137] In Figure 13, the entirety of L pixels 113L-1 and R pixels 113R-1, and L pixels 113L-2 and R pixels 113R-2, functions as a single image plane phase-difference pixel 113P''. That is, in the image plane phase-difference pixel 113P'' of Figure 13, L pixels 113L-1 and 113L-2 function as a single L pixel 113ZL enclosed by the dashed line in the figure, and R pixels 113R-1 and 113R-2 function as a single R pixel 113ZR enclosed by the dashed line in the figure.

[0138] In the image plane phase difference pixel configuration 113P'' shown in Figure 13, the L pixel 113ZL and R pixel 113ZR are each formed perpendicular to the off-angle direction DAoff. Therefore, the separation structure 171D is formed by injecting implantable impurities along the off-angle direction DAoff in the TrueZero direction (direction D in the figure). As a result, the separation structure 171D evenly separates the L pixel 113ZL and R pixel 113ZR, thereby suppressing inhomogeneity in the pixel characteristics of the L pixel 113ZL and R pixel 113ZR.

[0139] <<3. Second Embodiment>> In the above, we have described an example in which the L pixel 113L and R pixel 113R constituting the image plane phase difference pixel 113P are each formed in a direction perpendicular to the off-angle direction DAoff.

[0140] However, if the wafer 100 on which the photodetector 101 is formed does not have an off-angle Aoff (off-angle Aoff = 0), then the crystal planes Fc and FC of the wafer 100 coincide with the normal direction of the wafer 100. Therefore, by simply injecting implant impurities from the normal direction (direction Dtil), the L pixels 113L and R pixels 113R are not diffused unbalanced in the horizontal direction when separated. Thus, non-uniformity of pixel characteristics between adjacent pixels can be suppressed without restricting the arrangement of the L pixels 113L and R pixels 113R in the planar direction.

[0141] More specifically, as shown in Figure 14, for example, the wafer 100A is sliced ​​perpendicular to the central axis direction Nsi in block 32', that is, with an off-angle Aoff (cutting angle = Aoff) = 0°, in a state without inclination. Here, we will proceed with the explanation assuming that the off-angle Aoff (cutting angle = Aoff) = 0°, but it does not have to be exactly 0° as long as it does not affect the diffusion direction of implant impurities. For example, a range of approximately 0°-0.1° < off-angle Aoff < 0°+0.1° can be considered acceptable. In other words, it is sufficient for the wafer 100A to be produced by slicing with an almost no cutting angle (approximately 0°-0.1° < off-angle Aoff < 0°+0.1°).

[0142] Furthermore, in the following steps, the normal direction Nw of the wafer 100A coincides with the crystal direction (the axis direction of the cylindrical body) Nsi, so the off-angle Aoff (cutting angle = Aoff) becomes 0, and there is no off-angle direction DAoff on which the off-angle Aoff is projected.

[0143] When forming image plane phase difference pixels 113PP using the wafer 100A generated in this manner, the off-angle Aoff (cutting angle = Aoff) of the wafer 100A becomes 0°, as shown in the left part of Figure 15. That is, the surface of the wafer 100A and the crystal plane constituting the wafer 100A coincide, so in other words, on the surface of the wafer 100, the directions parallel to the crystal plane constituting the wafer 100 are all directions. Therefore, the L pixels 113L and R pixels 113R separated by the separation structure 171E can be arranged in any orientation on the wafer 100A.

[0144] Note that the image plane phase difference pixels 113PP in Figure 15 are denoted by the same reference numerals as the image plane phase difference pixels 113P in Figure 9, and their explanations are omitted.

[0145] In the image plane phase difference pixel 113PP of Figure 15, the differences from the image plane phase difference pixel 113P of Figure 9 are that it is formed on a wafer 100A with an off angle Aoff (cutout angle = Aoff) = 0°, and that a separation structure 171E is provided instead of the separation structure 171, and the separation structure 171E is formed by injecting implantable impurities from direction Dtil at the central position of the L pixel 113L and the R pixel 113R.

[0146] In other words, in the case of Figure 15, when forming the separation structure 171E, as shown in the upper left and upper center of Figure 15, implant impurities are injected in the direction Dtil, which is the normal direction to the surface (crystal plane FC) of the wafer 100A, at the central position of the L pixel 113L and the R pixel 113R, that is, perpendicular to the surface of the wafer 100A.

[0147] In the image plane phase difference pixel 113PP configuration shown in Figure 15, the off-angle Aoff (cutting angle = Aoff) of the wafer 100A is 0°. Therefore, even if the L pixels 113L and R pixels 113R are formed without restriction on the direction in which they are positioned relative to the surface of the wafer 100A, a separation structure 171E will be formed at the central position of the L pixels 113L and R pixels 113R by injecting implantable impurities from the TiltZero direction (direction Dtil = TrueZero direction). As a result, the separation structure 171E evenly separates the L pixels 113L and R pixels 113R, making it possible to suppress inhomogeneity of pixel characteristics between adjacent pixels of the L pixels 113L and R pixels 113R.

[0148] Furthermore, the image plane phase difference pixels 113PP generated using a wafer 100A with an off-angle Aoff (cutting angle = Aoff) = 0° can be applied to any of the image plane phase difference pixel layouts 113P' to 113P''' described above with reference to Figures 10 to 13. However, even in this case, when constructing the separation structure 171, the implant impurities are injected from the TiltZero direction (direction Dtil) at the central position of the L pixel 113L and the R pixel 113R.

[0149] <<4. Examples of application to electronic devices>> The light detection device 101 shown in Figure 6 above can be applied to various electronic devices such as imaging devices like digital still cameras and digital video cameras, mobile phones equipped with imaging functions, or other devices equipped with imaging functions.

[0150] Figure 16 is a block diagram showing an example configuration of an imaging device as an electronic device to which this technology is applied.

[0151] The imaging device 501 shown in Figure 16 comprises an optical system 502, a shutter device 503, a solid-state image sensor 504, a drive circuit 505, a signal processing circuit 506, a monitor 507, and a memory 508, and is capable of capturing both still and moving images.

[0152] The optical system 502 is composed of one or more lenses and guides light from the subject (incident light) to the solid-state image sensor 504, forming an image on the light-receiving surface of the solid-state image sensor 504.

[0153] The shutter device 503 is positioned between the optical system 502 and the solid-state image sensor 504, and controls the light irradiation period and light shielding period for the solid-state image sensor 504 according to the control of the drive circuit 1005.

[0154] The solid-state image sensor 504 is comprised of a package including the solid-state image sensor described above. The solid-state image sensor 504 accumulates signal charge for a certain period of time in response to light imaged onto the light-receiving surface via the optical system 502 and shutter device 503. The signal charge accumulated in the solid-state image sensor 504 is transferred according to a drive signal (timing signal) supplied from the drive circuit 505.

[0155] The drive circuit 505 drives the solid-state image sensor 504 and the shutter device 503 by outputting drive signals that control the transfer operation of the solid-state image sensor 504 and the shutter operation of the shutter device 503.

[0156] The signal processing circuit 506 performs various signal processing operations on the signal charge output from the solid-state image sensor 504. The image (image data) obtained by the signal processing circuit 506 is supplied to the monitor 507 for display or supplied to the memory 508 for storage (recording).

[0157] Even in the imaging device 501 configured in this way, by applying the photodetector 101 shown in Figure 6 instead of the solid-state image sensor 504 described above, it becomes possible to suppress variations in the pixel characteristics of the L pixels and R pixels that constitute the image plane phase difference pixels.

[0158] <<5. Examples of Solid State Imaging Device Use>>

[0159] Figure 17 shows an example of use using the above-described photodetector 101.

[0160] The above-described light detection device 101 can be used in various cases for sensing light such as visible light, infrared light, ultraviolet light, and X-rays, for example, as follows.

[0161] - Devices that capture images for viewing purposes, such as digital cameras and portable devices with camera functions. - Devices used for traffic purposes, such as in-vehicle sensors that capture images of the front, rear, surroundings, and interior of a vehicle for safe driving such as automatic stopping and recognition of the driver's condition, surveillance cameras that monitor moving vehicles and roads, and distance measuring sensors that measure distances between vehicles. - Devices used in home appliances such as TVs, refrigerators, and air conditioners that capture user gestures and allow device operation according to those gestures. - Devices used for medical and healthcare purposes, such as endoscopes and devices that perform angiography using infrared light reception. - Devices used for security purposes, such as surveillance cameras for crime prevention and cameras for person recognition. - Devices used for beauty purposes, such as skin measuring devices that capture images of skin and microscopes that capture images of the scalp. - Devices used for sports purposes, such as action cameras and wearable cameras for sports use. - Devices used for agriculture, such as cameras that monitor the condition of fields and crops.

[0162] Furthermore, this disclosure can also be structured as follows:

[0163] <1> A photodetector comprising a separation structure formed on a substrate for separating a first pixel and a second pixel that are adjacent to each other, wherein the first pixel and the second pixel are arranged on the substrate in a direction parallel to the surface of the substrate and the crystal plane constituting the substrate. <2> The photodetector according to <1>, wherein the first pixel and the second pixel function as image plane phase difference detection pixels. <3> The photodetector according to <1>, wherein the substrate is formed from a wafer having a predetermined cutting angle, and the first pixel and the second pixel are arranged on the substrate in a direction perpendicular to the direction forming the cutting angle, such that the surface of the substrate and the crystal plane constituting the substrate are parallel to each other. <4> The photodetector according to <1>, wherein the separation structure is formed by injecting implant impurities between adjacent first pixels and second pixels. <5> The photodetector according to <4>, wherein the implant impurities are injected between adjacent first pixels and second pixels in a direction perpendicular to the crystal plane forming the substrate. <6> The photodetector according to <4>, wherein the implant impurity is injected perpendicular to the surface of the substrate between adjacent first and second pixels. <7> The photodetector according to <4>, wherein the first and second pixels are formed surrounded by a rectangular interpixel wall, and a protrusion is formed between adjacent first and second pixels extending from the interpixel wall, with a gap formed in part of the protrusion, and the separation structure is formed to fill the gap. <8> The photodetector according to <7>, wherein two protrusions are formed between the first and second pixels, extending opposite to each other from opposing interpixel walls, with a gap formed between the tips of the two protrusions, and the separation structure is formed across the two protrusions to fill the gap.<9> When the first pixel and the second pixel, surrounded by the rectangular interpixel wall, form a pair, and two pairs are arranged adjacent to each other with the interpixel wall in between, coaxially with a protrusion formed between the first pixel and the second pixel extending from the interpixel wall, the separation structure is formed to span across the gap between each of the two pairs collectively, as described in <8>. <10> Between the first pixel and the second pixel, one protrusion is formed extending from one interpixel wall to the other interpixel wall, and a gap is formed between the tip of the protrusion and the other interpixel wall, and the separation structure is formed to fill the gap, as described in <7>. <11> When the first pixel and the second pixel, surrounded by the rectangular interpixel wall, form a pair, and two pairs are arranged adjacent to each other with the interpixel wall in between, coaxially with a protrusion formed between the first pixel and the second pixel extending from the interpixel wall, the separation structure is formed to fill the gaps between the two adjacent interpixel walls in one piece, straddling the interpixel wall. The light detection device according to <10>. <12> The photodetector according to <7>, wherein two first pixels and two second pixels are arranged in a 2x2 pixel arrangement on the substrate in a direction parallel to the surface of the substrate and the crystal plane constituting the substrate, and the whole is enclosed in a rectangular shape by the interpixel wall, four protrusions are formed at each adjacent boundary between the two first pixels and the two second pixels, extending from the center of the interpixel wall to near the center of the rectangular shape, a gap is formed near the tips of the four protrusions, and the separation structure is formed to fill the gap. <13> The photodetector according to <1>, wherein the substrate is formed from a wafer without a predetermined cutting angle, and the first pixels and second pixels are arranged on the substrate in an arbitrary direction such that the surface of the substrate and the crystal plane constituting the substrate are parallel. <14> The photodetector according to <1>, wherein the substrate is one of a 0-degree substrate, a 45-degree substrate, a carbon light-doped substrate, and a low-oxygen concentration substrate.

[0164] 32' block, 100, 100A, 100A' wafer, 101 photodetector, 113P, 113P-1, 113P-2, 113P'-1, 113P'-2, 113P'', 113PP, 113PPPP image plane phase difference pixels, 113L, 113L-1, 113L-2 L pixels, 113R, 113R-1, 113R-2 R pixels, 123, 123-1, 123-2, 123L-1, 123L-2, 123R-1, 123R-2, 123D floating diffusion layer (FD), 155 interpixel wall, 155a, 155a-1, 155a-2, 155a-1-1, 155a-1-2, 155a-2-1, 155a-2-2, 155a-1, 155a-11 to 155a-14 protrusions, 161, 161R, 161R-1, 161R-2, 161L, 161L-1, 161L-2 ground potential (GND), 171, 171A, 171B-1, 171B-2, 171C, 171E, 171E', 181 inter-pixel wall

Claims

1. A photodetector comprising a separation structure formed on a substrate for separating a first pixel and a second pixel that are adjacent to each other, wherein the first pixel and the second pixel are arranged on the substrate in a direction parallel to the surface of the substrate and the crystal plane constituting the substrate.

2. The light detection device according to claim 1, wherein the first pixel and the second pixel function as image plane phase difference detection pixels.

3. The photodetector according to claim 1, wherein the substrate is formed from a wafer having a predetermined cutting angle, and the first pixel and the second pixel are arranged on the substrate in a direction perpendicular to the direction forming the cutting angle, such that the surface of the substrate and the crystal plane constituting the substrate are parallel.

4. The photodetector according to claim 1, wherein the separation structure is formed by injecting an implantable impurity between adjacent first and second pixels.

5. The photodetector according to claim 4, wherein the implanted impurity is injected between adjacent first and second pixels in a direction perpendicular to the crystal plane forming the substrate.

6. The photodetector according to claim 4, wherein the implanted impurity is injected perpendicular to the surface of the substrate between adjacent first and second pixels.

7. The photodetector according to claim 4, wherein the first pixel and the second pixel are formed surrounded by a rectangular interpixel wall, a protrusion is formed between adjacent first and second pixels extending from the interpixel wall, a gap is formed in part of the protrusion, and the separation structure is formed to fill the gap.

8. The photodetector according to claim 7, wherein two protrusions are formed between the first pixel and the second pixel, extending opposite to each other from the opposing inter-pixel walls, a gap is formed between the tips of the two protrusions, and the separation structure is formed across the two protrusions to fill the gap.

9. When the first pixel and the second pixel, surrounded by the rectangular interpixel wall, form a pair, and two pairs are arranged adjacent to each other with the interpixel wall in between, coaxially with a protrusion formed extending from the interpixel wall between the first pixel and the second pixel, the separation structure is formed to span across the gap between each of the two pairs collectively, as described in claim 8.

10. The photodetector according to claim 7, wherein a protrusion is formed between the first pixel and the second pixel, extending from one inter-pixel wall to the other inter-pixel wall, a gap is formed between the tip of the protrusion and the other inter-pixel wall, and the separation structure is formed to fill the gap.

11. When the first pixel and the second pixel, surrounded by the rectangular interpixel wall, form a pair, and two pairs are arranged adjacent to each other across the interpixel wall, with a protrusion formed between the first pixel and the second pixel extending from the interpixel wall and coaxial with the interpixel wall, the separation structure is formed to fill the gaps between the two adjacent interpixels across the interpixel wall in a single unit, spanning the interpixel wall, according to claim 10.

12. The photodetector according to claim 7, wherein two first pixels and two second pixels are arranged in a 2x2 pixel configuration on the substrate such that the surface of the substrate and the crystal planes constituting the substrate are parallel, and the entire structure is enclosed in a rectangular shape by the inter-pixel walls, and four protrusions are formed at each adjacent boundary between the two first pixels and the two second pixels, extending from the center of the inter-pixel wall to near the center of the rectangular shape, and the gap is formed near the tips of the four protrusions, and the separation structure is formed to fill the gap.

13. The photodetector according to claim 1, wherein the substrate is formed from a wafer without a predetermined cutting angle, and the first pixel and the second pixel are arranged on the substrate in any direction such that the surface of the substrate and the crystal plane constituting the substrate are parallel.

14. The photodetector according to claim 1, wherein the substrate is one of a 0-degree substrate, a 45-degree substrate, a carbon light-doped substrate, and a low-oxygen concentration substrate.

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