Photovoltaic conversion device, photovoltaic conversion system, moving body

Abstract

To simultaneously improve the sensitivity of a photoelectric conversion device to light in the near-infrared region and suppress optical crosstalk.SOLUTION: A photoelectric conversion device has a semiconductor layer formed of silicon. A pixel separation portion is formed inside the semiconductor layer to separate each pixel. The pixel separation portion has a metal filling portion and a dielectric film provided on a side of the metal filling portion. The material of the metal filling portion is copper. The material of the dielectric film is silicon oxide. The thickness of the dielectric film is 50 nm or more and 270 nm or less.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a photoelectric conversion device, a photoelectric conversion system, and a moving body.

Background Art

[0002] As a technique for improving the light sensitivity of a photoelectric conversion device (solid-state imaging device), a back-illuminated CMOS image sensor (Patent Document 1) provided with a periodic uneven structure portion on a light-receiving surface is known. Light incident on the photoelectric conversion device is diffracted by the periodic uneven structure portion. The diffracted light is reflected in a pixel isolation portion having a groove structure and confined within one pixel. When a periodic uneven structure portion is provided on the light-receiving surface, the optical path length is extended as compared with the case where light travels straight through the pixel without the periodic uneven structure portion provided on the light-receiving surface. Therefore, an improvement in sensitivity for the near-infrared region where the light absorption coefficient of silicon is particularly small can be expected.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Technology 1, when a metal material having high light shielding properties is filled in DTI (Deep Trench Isolation) which is a pixel isolation portion, light crosstalk (light leakage) to adjacent pixels can be suppressed, and optical color mixing and resolution degradation can be reduced. However, due to the influence of light absorption by the metal material, the light sensitivity of the photoelectric conversion device may decrease. On the other hand, when a dielectric is filled in DTI, since the influence of light absorption such as that of a metal material is small, an improvement in the sensitivity of the photoelectric conversion device can be achieved. However, since the dielectric has inferior light shielding properties compared to the metal material, optical color mixing and resolution degradation due to light crosstalk may occur.

[0005] Therefore, an object of the present invention is to simultaneously improve the sensitivity of a photoelectric conversion device to light in the near-infrared region and suppress optical crosstalk.

Means for Solving the Problems

[0006] One aspect of the present invention is a photoelectric conversion device having a semiconductor layer formed of silicon, wherein a pixel isolation part for separating each pixel is formed inside the semiconductor layer, the pixel isolation part has a metal filling part and a dielectric film provided on a side part of the metal filling part, Light with a wavelength of 750 nm or more and 2500 nm or less is incident on the pixel. the material of the metal filling part is copper, the material of the dielectric film is Two oxide Silicon and Surrounding the side portion of the metal filling portion the thickness of the dielectric film is 50 nm or more and 270 nm or less, characterized by a photoelectric conversion device.

[0007] One aspect of the present invention is a photoelectric conversion device having a semiconductor layer formed of silicon, wherein a pixel isolation part for separating each pixel is formed inside the semiconductor layer, the pixel isolation part has a metal filling part and a dielectric film provided on a side part of the metal filling part, Light with a wavelength of 750 nm or more and 2500 nm or less is incident on the pixel. the material of the metal filling part is tungsten, the material of the dielectric film is Two oxide Silicon and Surrounding the side portion of the metal filling portion the thickness of the dielectric film is 130 nm or more and 250 nm or less, characterized by a photoelectric conversion device.

[0008] One aspect of the present invention is a photoelectric conversion device having a semiconductor layer formed of silicon, wherein a pixel separation part for separating each pixel is formed inside the semiconductor layer, the pixel separation part has a metal filling part and a dielectric film provided on a side part of the metal filling part, Light with a wavelength of 750 nm or more and 2500 nm or less is incident on the pixel. the material of the metal filling part is cobalt, the material of the dielectric film is Two oxide Silicon and Surrounding the side portion of the metal filling portion the thickness of the dielectric film is 110 nm or more and 270 nm or less, characterized by being a photoelectric conversion device.

[0009] One aspect of the present invention is a photoelectric conversion device having a semiconductor layer formed of silicon, wherein a pixel separation part for separating each pixel is formed inside the semiconductor layer, the pixel separation part has a metal filling part and a dielectric film provided on a side part of the metal filling part, Light with a wavelength of 750 nm or more and 2500 nm or less is incident on the pixel. the material of the metal filling part is aluminum, the material of the dielectric film is Two oxide Silicon and Surrounding the side portion of the metal filling portion the thickness of the dielectric film is 60 nm or more and 250 n m or less, characterized by being a photoelectric conversion device.

Advantages of the Invention

[0010] According to the present invention, it is possible to simultaneously improve the sensitivity of the photoelectric conversion device to light in the near-infrared region and suppress optical crosstalk.

Brief Description of the Drawings

[0011]

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Modes for Carrying Out the Invention

[0012] First, the terms used in this specification will be described. Hereinafter, the "back side" refers to the light incident side (light incident surface side) of the photoelectric conversion device which is a back-illuminated CMOS image sensor. Also, the "front side" refers to the side opposite to the back side. The pixel isolation part having a groove structure in the photoelectric conversion device may be denoted as DTI (Deep Trench Isolation).

[0013] In the following embodiments, for the DTI filled with a metal material, the thickness of the dielectric film provided on the side portion of the DTI is set to be equal to or greater than a predetermined thickness. As a result, the DTI can have both properties of high light shielding property and low light absorption property, so that it is possible to simultaneously improve the sensitivity of the photoelectric conversion device and suppress optical crosstalk. Note that hereinafter, the thickness of the inside or side portion of the DTI is the length in a direction perpendicular to the direction in which the DTI extends. Also, the thickness of the inside or side portion of the DTI is the length in a direction perpendicular to the direction in which the layers of the photoelectric conversion device are stacked, and can be said to be the length in a direction parallel to the main surface of the substrate of the photoelectric conversion device.

[0014] In each of the embodiments described below, as an example of the photoelectric conversion device, an imaging device will be mainly described. However, each embodiment is not limited to the imaging device, and is also applicable to other examples of the photoelectric conversion device. For example, there are a distance measuring device (a device for distance measurement using focus detection or TOF (Time Of Flight)), a photometric device (a device for measuring the amount of incident light), and the like.

[0015] In this specification, "plan view" refers to viewing from a direction perpendicular to the surface on the side opposite to the light incident surface of the semiconductor layer described later. Also, a cross section refers to a surface in a direction perpendicular to the surface on the side opposite to the light incident surface of the semiconductor layer. Note that when the light incident surface of the semiconductor layer is a rough surface when viewed microscopically, the plan view is defined based on the light incident surface of the semiconductor layer when viewed macroscopically.

[0016] (Problems occurring in the photoelectric conversion device) First, the mechanism of light absorption or light crosstalk to adjacent pixels in DTI will be described, and the problems occurring in a photoelectric conversion device to which each of the following embodiments is not applied will be described. Usually, the side and bottom surfaces of DTI are covered with a thin oxide film. And, the inside of DTI is filled with a material such as a dielectric, a metal material, or polysilicon. Note that voids may be left in a part of DTI.

[0017] FIG. 3A shows a part of a semiconductor layer in a photoelectric conversion device. And, FIG. 3A is a cross-sectional schematic view for explaining the transmission and reflection of light 1002 incident from silicon 1000 to DTI 1001. Incident angle 1004 is the incident angle of light 1002.

[0018] Here, when the transmittance of DTI 1001 is high, many components of light 1002 pass through DTI 1001, and the light crosstalk from the self pixel to adjacent pixels increases. On the other hand, when the reflectance of DTI 1001 is high, light 1002 is confined within the self pixel, contributing to an improvement in the light sensitivity of the photoelectric conversion device. Therefore, it is preferable to increase the reflectance while reducing the transmittance of DTI 1001. Note that the transmittance and reflectance depend on the configuration (thickness, material, and layer configuration) of DTI 1001, the light wavelength, and the incident angle.

[0019] FIGS. 3B and 3C show the calculation results of the incident angle dependence of the transmittance and reflectance when light having a wavelength of 940 nm among light in the near-infrared region is incident from silicon 1000 to DTI 1001. Here, assume that the thickness of DTI 1001 is 200 nm and SiO2 having a thickness of 10 nm is formed on DTI side portion 1003. And, FIGS. 3B and 3C show a graph comparing the transmittance and reflectance by changing the material filled in the region other than the region where SiO2 of DTI 1001 is formed. Note that for simplicity, the calculation was performed assuming that the height of DTI 1001 (the length in the direction in which DTI 1001 extends) is infinite. The material filled in DTI 1001 is each of SiO2 (silicon dioxide; silicon oxide), W (tungsten), Al (aluminum), Cu (copper), and Co (cobalt). The reflectance is compared.

[0020] When the DTI1001 is filled with dielectric SiO2, the light 1002 is reflected in the DTI1001 according to the refractive index difference between silicon and SiO2. If the light 1002 is visible light or infrared light, since the light absorption of SiO2 for the light 1002 is almost zero, the component of the light 1002 that is not reflected in the DTI1001 will transmit to the adjacent pixel. When the incident angle 1004 satisfies the total reflection condition, the light 1002 is completely reflected. Referring to FIGS. 3B and 3C, when the incident angle is 40 degrees or less, a part of the light 1002 transmits through the DTI1001. On the other hand, the light 1002 incident at an angle greater than 40 degrees is 100% reflected in the DTI1001.

[0021] Note that the critical angle of total reflection theoretically calculated from the refractive indices of silicon and SiO2 when the wavelength of light is 940 nm is 23.8 degrees, but the incident angle at which light is actually totally reflected is greater than 23.8 degrees. Specifically, an angle close to 40 degrees is the actual critical angle of total reflection. This is considered to be due to the fact that since the thickness of the DTI1001 is finite, the evanescent wave that has leaked into the SiO2 reaches the silicon of the adjacent pixel and is converted into propagating light. Here, the evanescent wave is a special electromagnetic wave that occurs when light is incident from a high refractive index phase to a low refractive index phase at an incident angle greater than the theoretical critical angle and reflection occurs.

[0022] As described above, in the photoelectric conversion device in which the DTI1001 is filled with a dielectric (SiO2), when the incident angle 1004 is large, most of the components of the light 1002 are reflected in the DTI1001 without loss. On the other hand, when the incident angle 1004 is small, there is a problem that light crosstalk to adjacent pixels occurs.

[0023] Also, when the DTI1001 is filled with a metal material, the component of the light 1002 that is not reflected by the DTI1001 is almost absorbed by the metal. Referring to FIGS. 3B and 3C, the transmittance of the light 1002 is almost zero regardless of the incident angle 1004. Also, unlike the case where the DTI1001 is filled with a dielectric, the reflectance of the DTI1001 does not vary significantly even when the incident angle 1004 changes. Note that the reflectance of the DTI1001 varies greatly depending on the metal material, but even the highest, Cu, does not reach 100%. This is because light absorption by the metal leads to light loss. When the light 1002 reaches the DTI1001 and light loss of the light 1002 occurs, it leads to a decrease in the sensitivity of the photoelectric conversion device.

[0024] As described above, when the DTI1001 is filled with a metal material, compared with the case of filling with a dielectric, there is an advantage that stable light shielding can be achieved regardless of the incident angle 1004, but there is a problem that it leads to a decrease in sensitivity.

[0025] (Circuit configuration of the photoelectric conversion device) The circuit configuration of the photoelectric conversion device according to each of the following embodiments will be described. The photoelectric conversion device is a back-illuminated solid-state imaging device. The photoelectric conversion device has an avalanche diode. When a reverse bias voltage is supplied to the avalanche diode, there is a Geiger mode in which the potential difference between the anode and the cathode operates in a state where it is larger than the breakdown voltage. Also, the avalanche diode has a linear mode in which the potential difference between the anode and the cathode operates in a state near or below the breakdown voltage.

[0026] An avalanche diode operating in the Geiger mode is called a SPAD (Single Photon Avalanche Diode). For example, the anode voltage is -30V, and the cathode voltage is It is 1V. The APD may operate in linear mode or Geiger mode. In the following, the photoelectric conversion device includes a SPAD (Single Photon Avalanche Diode) that counts the number of photons incident on the avalanche diode. Note that the photoelectric conversion device does not necessarily have to be a photoelectric conversion device having an avalanche diode, and it may be a distance sensor using LiDAR (Light Detection and Ranging) or an infrared sensor.

[0027] In the following description, the anode of the avalanche diode is set to a fixed potential, and a signal is taken out from the cathode side. Therefore, the first conductive type semiconductor region having carriers of the same conductivity type as the signal carrier as majority carriers is an N-type semiconductor region, and the second conductive type semiconductor region is a P-type semiconductor region. The cathode of the avalanche diode may be set to a fixed potential, and light may be taken out from the anode side. In this case, the first conductive type semiconductor region having carriers of the same conductivity type as the signal carrier as majority carriers is a P-type semiconductor region, and the second conductive type semiconductor region is an N-type semiconductor region.

[0028] FIG. 1 is a block diagram of the photoelectric conversion device. The photoelectric conversion device has a pixel unit 16, a control pulse generation unit 19, a horizontal scanning circuit unit 14, a control line 15, a signal line 17, a vertical scanning circuit unit 13, and an output circuit 18.

[0029] In the pixel unit 16, a plurality of pixels 1 are arranged two-dimensionally. One pixel 1 is composed of a photoelectric conversion unit 11 and a pixel signal processing unit 12. The photoelectric conversion unit 11 converts light into an electrical signal. The pixel signal processing unit 12 outputs the converted electrical signal to the output circuit 18.

[0030] The vertical scanning circuit unit 13 and the horizontal scanning circuit unit 14 receive the control pulses supplied from the control pulse generation unit 19 and supply the control pulses to each pixel 1. Logic circuits such as a shift register and an address decoder are used for the vertical scanning circuit unit 13.

[0031] The signal line 17 supplies, as a potential signal, the signal output from the pixel 1 selected by the vertical scanning circuit section 13 to the circuit at the subsequent stage of the pixel 1.

[0032] The output circuit 18 is composed of a buffer amplifier, a differential amplifier, etc., and outputs the signals output from each pixel 1 to a recording section or a signal processing section outside the photoelectric conversion device.

[0033] In FIG. 1, the arrangement of the pixels 1 in the pixel section 16 may be arranged in a one-dimensional (linear) manner. Also, the vertical scanning circuit section 13 and the horizontal scanning circuit section 14 may divide the pixel section 16 into a plurality of pixel columns as blocks and arrange them for each block. Further, the vertical scanning circuit section 13 and the horizontal scanning circuit section 14 may be arranged for each pixel column.

[0034] The functions of the pixel signal processing section 12 do not necessarily have to be provided one by one for all the pixels 1. For example, one pixel signal processing section 12 may be shared by a plurality of pixels 1, and signal processing may be performed sequentially. Also, the pixel signal processing section 12 may be provided on a semiconductor substrate different from the photoelectric conversion section 11 in order to increase the aperture ratio of the photoelectric conversion section 11. In this case, the photoelectric conversion section 11 and the pixel signal processing section 12 are electrically connected via connection wirings provided for each pixel. The vertical scanning circuit section 13, the horizontal scanning circuit section 14, and the signal line 17 may also be provided on different semiconductor substrates as described above.

[0035] FIG. 2 is a block diagram of a pixel 1 including an equivalent circuit. In FIG. 2, one pixel 1 has a photoelectric conversion section 11 and a pixel signal processing section 12. The photoelectric conversion section 11 has an avalanche diode 21 and a quench element 22. The avalanche diode 21 generates electron-hole pairs corresponding to incident light by photoelectric conversion. An anode is connected to the cathode of the avalanche diode 21 A potential based on a potential VH higher than the potential VL supplied to the drain is supplied. Then, to the anode and cathode of the avalanche diode 21, a potential is supplied such that a reverse bias is applied so that the photons incident on the avalanche diode 21 are avalanche multiplied. By performing photoelectric conversion in a state where such a reverse bias potential is supplied, the charges generated by the incident light cause avalanche multiplication and an avalanche current is generated.

[0036] Note that when a reverse bias potential is supplied, when the potential difference between the anode and the cathode is greater than the breakdown voltage, the avalanche diode operates in Geiger mode. An avalanche diode that uses Geiger mode operation to rapidly detect a weak signal at the single photon level is a SPAD (Single Photon Avalanche Diode).

[0037] The quench element 22 is connected to the power supply that supplies the high potential VH and the avalanche diode 21. The quench element 22 is composed of a P-type MOS transistor or a resistive element such as a diffusion resistor. When the photocurrent is multiplied by avalanche multiplication in the avalanche diode, the current obtained by the multiplied signal charges flows to the connection node between the avalanche diode 21 and the quench element 22. Due to the voltage drop caused by this current, the potential of the cathode of the avalanche diode 21 decreases, and the avalanche diode 21 no longer forms an electron avalanche. As a result, the avalanche multiplication of the avalanche diode 21 stops. Thereafter, since the potential VH of the power supply is supplied to the cathode of the avalanche diode 21 via the quench element 22, the potential supplied to the cathode of the avalanche diode 21 returns to the potential VH. That is, the operating region of the avalanche diode 21 again becomes Geiger mode operation. In this way, the quench element 22 functions as a load circuit (quench circuit) during signal amplification by avalanche multiplication and has the function of suppressing avalanche multiplication (quench operation). Further, the quench element has the function of returning the operating region of the avalanche diode to Geiger mode again after suppressing avalanche multiplication.

[0038] The pixel signal processing unit 12 includes a waveform shaping unit 23, a counter circuit 29, and a selection circuit 26. The waveform shaping unit 23 shapes the potential change of the cathode of the avalanche diode 21 obtained at the time of photon detection and outputs a pulse signal. For example, an inverter circuit is used as the waveform shaping unit 23. In addition, although an example using one inverter is shown as the waveform shaping unit 23, a circuit in which a plurality of inverters are connected in series may be used, or other circuits having a waveform shaping effect may be used.

[0039] The pulse signal output from the waveform shaping unit 23 is counted by the counter circuit 29. In the case of, for example, an N-bit counter (N: a positive integer) in the counter circuit 29, it is possible to count up to about 2 to the Nth power of the pulse signal due to a single photon. The counted signal is held as the detected signal. Also, when a control pulse pRES is supplied via the control line 15, the signal held in the counter circuit 29 is reset.

[0040] The selection circuit 26 is supplied with a control pulse pSEL from the vertical scanning circuit unit 13 in FIG. 1 via the control line 15 in FIG. 2, and switches the electrical connection and non-connection between the counter circuit 29 and the signal line 17. The selection circuit 26 includes, for example, a buffer circuit for outputting a signal.

[0041] Note that a switch such as a transistor may be arranged between the quench element 22 and the avalanche diode 21, or between the photoelectric conversion unit 11 and the pixel signal processing unit 12 to switch the electrical connection. Similarly, the supply of the high potential VH or the low potential VL supplied to the avalanche diode 21 may be electrically switched using a switch such as a transistor.

[0042] In the pixel unit 16 in which a plurality of pixels 1 are arranged in a matrix, the imaging image may be acquired by a rolling shutter operation in which the counting of the counter circuit 29 is sequentially reset for each row, and the signal held in the counter circuit 29 is sequentially output for each row.

[0043] Alternatively, an imaging image may be obtained by a global electronic shutter operation that simultaneously resets the counts of the counter circuits 29 for all pixel rows and sequentially outputs the signals held in the counter circuits 29 row by row. When performing the global electronic shutter operation, it is preferable to provide means for switching between the case where the counter circuits 29 perform counting and the case where they do not. The switching means is, for example, the switch described above.

[0044] In the above, a configuration for obtaining an imaging image using the counter circuit 29 has been shown. However, instead of the counter circuit 29, a time-to-digital converter (hereinafter referred to as TDC) and a memory may be used as a photoelectric conversion device that acquires pulse detection timing.

[0045] At this time, the generation timing of the pulse signal output from the waveform shaping unit 23 is converted into a digital signal by the TDC. The TDC is supplied with a control pulse pREF (reference signal) from the vertical scanning circuit unit 13 in FIG. 1 via a driving line for measuring the timing of the pulse signal. The TDC acquires, as a digital signal, a signal when the input timing of the signal output from each pixel via the waveform shaping unit 23 is a relative time with respect to the control pulse pREF as a reference.

[0046] <Embodiment 1> An example of a photoelectric conversion device provided with a DTI as a pixel separation part between pixels of the photoelectric conversion device will be described with reference to FIGS. 4 to 6B. In the present embodiment, in the DTI, since the thickness of the dielectric film provided on the side portion of the metal filling portion is equal to or greater than a predetermined value, high light shielding property and low light absorption property of the DTI with respect to light in the near-infrared region (light having a wavelength of 750 nm or more and 2500 nm or less) can be achieved simultaneously. In the following, it is assumed that the pixel size of the photoelectric conversion device having the SPAD according to Embodiment 1 is 5 μm or more and 10 μm or less in order to detect light in the near-infrared region. For this reason, even if the width of the DTI itself is relatively large, the influence on the sensitivity reduction of the photoelectric conversion unit 201 is small. On the other hand, it is assumed that the pixel size of a photoelectric conversion device used in a conventional smartphone or the like is 1 μm or less. For this reason, in a photoelectric conversion device used in a conventional smartphone or the like, in order to affect the sensitivity reduction, it was not assumed to increase the thickness of the DTI itself (for example, to 200 nm or more), and thus the thickness of the dielectric was not assumed to be increased.

[0047] FIG. 4 is a schematic cross-sectional view of one pixel of a photoelectric conversion device (solid-state imaging device) according to Embodiment 1. The photoelectric conversion device includes a semiconductor layer 10, a light shielding film 102, a microlens 105, a color filter 106, a metal wiring 108, and an interlayer insulating film 109. The semiconductor layer 10 is formed of silicon 100. Inside the semiconductor layer 10, a periodic uneven structure portion 101 and a DTI 20 (pixel separation portion) are formed. The semiconductor layer 10 includes at least the photoelectric conversion unit 201 described above. The DTI 20 has a DTI interior 103 and a DTI side portion 104. Note that the DTI 20 surrounds the pixels in a plan view to separate the respective pixels.

[0048] The incident light 107 passes through the microlens 105 and the color filter 106 and enters the silicon 100 from the back side of the photoelectric conversion device. In each embodiment, it is assumed that the wavelength of the incident light 107 after passing through the color filter 106 is 940 nm.

[0049] On the back surface side interface of the silicon 100 (semiconductor layer 10), a periodic uneven structure portion 101 is formed. Dry etching or wet etching is performed on the interface of the silicon 100, and recesses are periodically formed, and an insulator such as SiO2 is embedded, whereby the periodic uneven structure portion 101 is formed. The incident light 107 is diffracted by the periodic uneven structure portion 101 As a result, the incident light 107 is bent in various directions. The incident light 107 traveling in an oblique direction is reflected in the DTI 20 and travels zigzag within the silicon 100. Thereby, the effective optical path length of the incident light 107 when passing through the inside of the silicon 100 is extended. As a result, in particular, the sensitivity of the photoelectric conversion device with respect to the incident light 107 in the near-infrared region where the absorption coefficient in the silicon 100 is small is improved.

[0050] The DTI side portion 104 is a thin film made of dielectric SiO2 and surrounds the DTI interior 103. The DTI interior 103 is a metal-filled portion (region) filled with Cu as a metal material. The thickness of the DTI interior 103 (the metal-filled portion filled with Cu) is 180 nm. A light-shielding film 102 is provided on the upper part of the DTI 20. The material forming the light-shielding film 102 may be the same as the metal material filled in the DTI interior 103 or may be a different material. On the surface side of the silicon 100, a wiring layer 30 having a metal wiring 108 and an interlayer insulating film 109 is disposed. The wiring layer 30 may have a reflector (wiring) that reflects the incident light 107 incident on the wiring layer 30.

[0051] Here, consider the case where the incident light 107 diffracted by the periodic uneven structure portion 101 reaches the DTI 20. FIGS. 5A and 5B show the calculation results of the transmittance and reflectance of the DTI 20 with respect to light having a wavelength of 940 nm (hereinafter, light having this wavelength is referred to as "near-infrared light") when the thickness of the DTI side portion 104 is changed. The thickness of the DTI side portion 104 is the thickness by which the DTI side portion 104 surrounds the DTI interior 103 and is the length indicated by the width W in FIG. 4. Note that the light is not limited to light having a wavelength of 940 nm, and any light in the near-infrared region (light having a wavelength of 750 nm or more and 2500 nm or less), preferably light having a wavelength of 850 nm or more, can obtain the same effect as in this embodiment. As described above, the near-infrared light diffracted in the periodic uneven structure portion 101 is incident on the DTI 20 at various angles. Here, FIGS. 5A and 5B show the results of calculating the transmittance and reflectance for each incident angle of the near-infrared light. Note that the incident angle is the angle described with reference to FIG. 3A (the angle at which the incident light 107 is incident on the DTI 20 from outside the DTI 20).

[0052] As shown in FIG. 5A, the transmittance of the DTI 20 with respect to the near-infrared light is almost zero regardless of the thickness of the DTI side portion 104 or the incident angle. On the other hand, as shown in FIG. 5B, the reflectance of the DTI 20 with respect to the near-infrared light increases in value for almost all incident angles as the thickness of the DTI side portion 104 increases to 10 nm, 50 nm, and 100 nm. In particular, in the range where the incident angle is 40 degrees or more, as the thickness of the DTI side portion 104 increases, the reflectance almost reaches 100%. Note that the light that is not transmitted or reflected is absorbed by the DTI 20.

[0053] Figures 6A and 6B show the results of more detailed calculations of the influence of the thickness of the DTI side portion 104 on the reflectivity of DTI 20. Figure 6A shows the calculation results of the reflectivity of DTI 20 when the incident angle is fixed at 40 degrees (an angle close to the actual critical angle described above) and the thickness of the DTI side portion 104 is changed. Here, since the reflectivity of DTI 20 becomes approximately 100% when the incident angle is greater than 40 degrees, the calculation is performed with the incident angle fixed at 40 degrees, which is slightly smaller than that. When the incident angle is 40 degrees, the reflectivity of DTI 20 increases and approaches 100% as the thickness of the DTI side portion 104 increases.

[0054] This can be considered as follows. When near-infrared light is incident from silicon 100 to the SiO2 of the DTI side portion 104, the incident angle of 40 degrees is ideally greater than or equal to the critical angle of total reflection. Therefore, ideally, the near-infrared light is totally reflected in DTI 20. However, when the thickness of the DTI side portion 104 is not sufficient, a part of the light that has penetrated into the SiO2 reaches Cu as an evanescent wave, and light absorption occurs in Cu. As a result, the reflectivity of DTI 20 decreases. On the other hand, as the thickness of the DTI side portion 104 increases, the component of light reaching Cu (inside DTI 103) decreases, and the reflectivity of DTI 20 for near-infrared light approaches 100%. reflectivity approaches 100%.

[0055] As shown in Figure 6A, when the incident angle is 40 degrees, the thickness of the DTI side portion 104 is preferably 50 nm or more to make the reflectivity of DTI 20 95.0% or more. The thickness of the DTI side portion 104 is preferably 70 nm or more to make the reflectivity of DTI 20 98.0% or more. The thickness of the DTI side portion 104 is preferably 90 nm or more to make the reflectivity of DTI 20 99.0% or more.

[0056] To make the reflectivity of DTI20 99.5% or more, the thickness of the DTI side portion 104 is preferably 110 nm or more. To make the reflectivity of DTI20 99.7% or more, the thickness of the DTI side portion 104 is preferably 130 nm or more. To make the reflectivity of DTI20 99.8% or more, the thickness of the DTI side portion 104 is preferably 150 nm or more. To make the reflectivity of DTI20 99.9% or more, the thickness of the DTI side portion 104 is preferably 170 nm or more.

[0057] Similarly, with the incident angle fixed at 10 degrees, the results of calculations similar to those in FIG. 6A are shown in FIG. 6B. Here, even if the periodic uneven structure portion 101 diffracts light, it is difficult to assume that the incident angle will be less than 10 degrees, so the calculation is performed with the incident angle fixed at 10 degrees, which is slightly larger than that. Since 10 degrees is below the critical angle of total reflection at the silicon and SiO2 interface, total reflection does not occur. Therefore, near-infrared light reaches Cu as propagating light and is reflected and absorbed by Cu. Then, as the thickness of the DTI side portion 104 changes, the degree of light interference changes, and as a result, the reflectivity of DTI20 changes. According to the calculation results in FIG. 6B, the reflectivity of DTI20 decreases when the thickness of the DTI side portion 104 exceeds about 200 nm.

[0058] As shown in FIG. 6B, when the incident angle is 10 degrees, to make the reflectivity of DTI20 98.0% or more, the thickness of the DTI side portion 104 is preferably 190 nm or less. To make the reflectivity of DTI20 97.0% or more, the thickness of the DTI side portion 104 is preferably 240 nm or less. To make the reflectivity of DTI20 96.0% or more, the thickness of the DTI side portion 104 is preferably 260 nm or less. To make the reflectivity of DTI20 95.0% or more, the thickness of the DTI side portion 104 is preferably 270 nm or less.

[0059] Here, in a photoelectric conversion device that detects and converts light with a long wavelength such as near-infrared light (light in the near-infrared region), the pixel size (the length of one side of one pixel) is desirably approximately 5 to 10 μm. And in silicon 100, near-infrared light is absorbed by about 10% as it travels a distance equal to the length of the pixel size. In Embodiment 1, since the near-infrared light travels while being reflected by the DTI 20, if less near-infrared light is absorbed by the DTI 20, it can be said that there are sufficient merits in reflecting it with the DTI 20. For example, after being reflected by the DTI 20, the near-infrared light travels at least the pixel size before being reflected by the DTI 20 again. At this time, 10% of the near-infrared light traveling through the silicon 100 is absorbed by the silicon 100. Therefore, if the DTI 20 absorbs more than 10% of the near-infrared light incident on the DTI 20 when reflecting at the DTI 20, the absorption by the DTI 20 will be greater than the absorption by the silicon 100. According to this, the sensitivity of the near-infrared light of the photoelectric conversion device cannot be sufficiently ensured. Therefore, ideally, the DTI 20 preferably has an absorption rate of near-infrared light of 10% or less, and more preferably 5% or less which is half of that. That is, the reflectance of the DTI 20 is desirably 90% or more, and more preferably 95% or more. Note that the reflectance of the DTI 20 is not limited to 90% or 95% or more, and if it has a higher reflectance than the conventional DTI as shown in FIG. 3C, the effects according to Embodiment 1 can be achieved.

[0060] As described above, in order to increase the reflectance of the DTI 20, when the incident angle of the light in the near-infrared region is large, the thickness of the DTI side portion 104 is preferably thicker, but considering the case where the incident angle is small, it is preferably not thicker than necessary. In this way, by appropriately adjusting the film thickness of the DTI side portion 104, the DTI 20 having both high light-shielding properties and low light-absorbing properties can be realized. Therefore, it is possible to simultaneously improve the light sensitivity of the photoelectric conversion device with respect to the light in the near-infrared region and suppress optical crosstalk.

[0061] <Embodiment 2> Using FIGS. 7A, 7B, 8A, and 8B, an example different from Embodiment 1 of the configuration of the photoelectric conversion device provided with DTI20 as a pixel separation portion between pixels will be described. The photoelectric conversion device according to Embodiment 2 is different from the photoelectric conversion device according to Embodiment 1 in that the metal material filled in DTI20 is Co (cobalt) instead of Cu, and the other configurations are the same.

[0062] FIGS. 7A and 7B show, similar to Embodiment 1, the calculation results of the transmittance and reflectance of DTI20 with respect to near-infrared light having a wavelength of 940 nm when the thickness of the DTI side portion 104 is changed. Similar to Embodiment 1, the transmittance of DTI20 is almost zero regardless of the thickness of the DTI side portion 104 or the incident angle. On the other hand, the reflectance of DTI20 increases for almost all incident angles as the thickness of the DTI side portion 104 increases to 10 nm, 50 nm, and 100 nm. In particular, in the range where the incident angle is 40 degrees or more, as the thickness of the DTI side portion 104 increases, the reflectance of DTI20 almost reaches 100%.

[0063] FIGS. 8A and 8B show the results of more detailed calculations of the influence of the thickness of the DTI side portion 104 on the reflectance of DTI20 with respect to near-infrared light. FIG. 8A is the calculation result of the reflectance of DTI20 according to the thickness of the DTI side portion 104 with the incident angle fixed at 40 degrees. Referring to FIG. 8A, similar to Embodiment 1, as the thickness of the DTI side portion 104 increases, the reflectance of DTI20 increases and approaches 100%. However, it can be seen that the thickness of the DTI side portion 104 required to reach the same reflectance of DTI20 is larger in Embodiment 2 (when filled with Co) than in Embodiment 1 (when filled with Cu). This is presumably because the light absorption of Co is larger than that of Cu, so it is necessary to further reduce the intensity of the evanescent wave reaching the metal material.

[0064] When the incident angle is 40 degrees, in order to make the reflectivity of DTI20 95.0% or more, the thickness of the DTI side portion 104 is preferably 110 nm or more. In order to make the reflectivity of DTI20 98.0% or more, the thickness of the DTI side portion 104 is preferably 140 nm or more. In order to make the reflectivity of DTI20 99.0% or more, the thickness of the DTI side portion 104 is preferably 170 nm or more.

[0065] In order to make the reflectivity of DTI20 99.5% or more, the thickness of the DTI side portion 104 is preferably 200 nm or more. In order to make the reflectivity of DTI20 99.7% or more, the thickness of the DTI side portion 104 is preferably 220 nm or more. In order to make the reflectivity of DTI20 99.8% or more, the thickness of the DTI side portion 104 is preferably 240 nm or more. In order to make the reflectivity of DTI20 99.9% or more, the thickness of the DTI side portion 104 is preferably 270 nm or more.

[0066] Similarly, with the incident angle fixed at 10 degrees, the results of the same calculation as in FIG. 8A are shown in FIG. 8B. In the calculation results of FIG. 8B, when the thickness of the DTI side portion 104 is around 150 nm, the reflectivity of DTI20 reaches a peak.

[0067] When the incident angle is 10 degrees, in order to make the reflectivity of DTI20 80.0% or more, the thickness of the DTI side portion 104 is preferably 210 nm or less. In order to make the reflectivity of DTI20 75.0% or more, the thickness of the DTI side portion 104 is preferably 240 nm or less. In order to make the reflectivity of DTI20 70.0% or more, the thickness of the DTI side portion 104 is preferably 250 nm or less. In order to make the reflectivity of DTI20 65.0% or more, the thickness of the DTI side portion 104 is preferably 270 nm or less. Note that if the reflectivity of DTI20 is 65.0% or more, a reflectivity more than 10% greater than that of the Co-filled DTI described with reference to FIG. 3C can be achieved. Therefore, the photoelectric conversion device according to this embodiment can sufficiently increase the light sensitivity compared to the photoelectric conversion device described with reference to FIG. 3C.

[0068] <Embodiment 3> Using FIGS. 9A, 9B, 10A, and 10B, an example different from Embodiment 1 and Embodiment 2 of the configuration of a photoelectric conversion device provided with DTI20 as a pixel separation portion between pixels will be described. The photoelectric conversion device according to Embodiment 3 is different from the photoelectric conversion device according to Embodiment 1 in that the metal material filled in DTI20 is W (tungsten) instead of Cu, and the other configurations are the same.

[0069] FIGS. 9A and 9B show the calculation results of the transmittance and reflectance of DTI20 in near-infrared light with a wavelength of 940 nm when the thickness of the DTI side portion 104 is changed, similar to Embodiment 1. Also in Embodiment 3, similar to Embodiment 1, the transmittance of DTI20 is almost zero regardless of the thickness of the DTI side portion 104 or the incident angle. The reflectance of DTI20 increases for almost all incident angles as the thickness of the DTI side portion 104 increases to 10 nm, 50 nm, and 100 nm. In particular, in the range where the incident angle is 40 degrees or more, as the thickness of the DTI side portion 104 increases, the reflectance of DTI20 for near-infrared light reaches almost 100%.

[0070] FIGS. 10A and 10B show the results of more detailed calculations of the influence of the thickness of the DTI side portion 104 on the reflectance of DTI20 for near-infrared light. FIG. 10A is the calculation result of the reflectance of DTI20 according to the thickness of the DTI side portion 104 with the incident angle fixed at 40 degrees. Referring to FIG. 10A, similar to Embodiment 1, as the thickness of the DTI side portion 104 increases, the reflectance of DTI20 increases and approaches 100%.

[0071] However, it can be seen that compared with Embodiment 1 (when filled with Cu) and Embodiment 2 (when filled with Co), in the case of filling with W in Embodiment 3, the thickness of the DTI side portion 104 required for the reflectance of DTI20 to reach the same value is larger. This is considered to be because, compared with Cu and Co, the light absorption of W is large, so it is necessary to further reduce the intensity of the evanescent wave reaching the metal material.

[0072] When the incident angle is 40 degrees, in order to make the reflectivity of DTI20 95.0% or more, the thickness of the DTI side portion 104 is preferably 130 nm or more. In order to make the reflectivity of DTI20 98.0% or more, the thickness of the DTI side portion 104 is preferably 170 nm or more. In order to make the reflectivity of DTI20 99.0% or more, the thickness of the DTI side portion 104 is preferably 200 nm or more.

[0073] In order to make the reflectivity of DTI20 99.5% or more, the thickness of the DTI side portion 104 is preferably 220 nm or more. In order to make the reflectivity of DTI20 99.7% or more, the thickness of the DTI side portion 104 is preferably 240 nm or more. In order to make the reflectivity of DTI20 99.8% or more, the thickness of the DTI side portion 104 is preferably 260 nm or more. In order to make the reflectivity of DTI20 99.9% or more, the thickness of the DTI side portion 104 is preferably 290 nm or more.

[0074] Similarly, with the incident angle fixed at 10 degrees, the results of the same calculations as in FIG. 10A are shown in FIG. 10B. In the calculation results of FIG. 10B, when the thickness of the DTI side portion 104 is around 150 nm, the reflectivity of DTI20 reaches a peak.

[0075] When the incident angle is 10 degrees, in order to make the reflectivity of DTI20 65.0% or more, the thickness of the DTI side portion 104 is preferably 200 nm or less. In order to make the reflectivity of DTI20 60.0% or more, the thickness of the DTI side portion 104 is preferably 220 nm or less. In order to make the reflectivity of DTI20 55.0% or more, the thickness of the DTI side portion 104 is preferably 240 nm or less. In order to make the reflectivity of DTI20 50.0% or more, the thickness of the DTI side portion 104 is preferably 250 nm or less. Note that if the reflectivity of DTI20 is 50.0% or more, a reflectivity 20% or more greater than that of the W-filled DTI described with reference to FIG. 3C can be achieved. Therefore, the photoelectric conversion device according to this embodiment can sufficiently increase the light sensitivity compared to the photoelectric conversion device described with reference to FIG. 3C.

[0076] <Embodiment 4> Using FIGS. 11A, 11B, 12A, and 12B, an example different from Embodiments 1 to 3 of the configuration of a photoelectric conversion device provided with DTI20 as a pixel separation portion between pixels will be described. The photoelectric conversion device according to Embodiment 4 is different from the photoelectric conversion device according to Embodiment 1 in that the metal material filled in DTI20 is Al (aluminum) instead of Cu, and other configurations are the same.

[0077] FIGS. 11A and 11B show the calculation results of the transmittance and reflectance of DTI20 with respect to near-infrared light having a wavelength of 940 nm when the thickness of the DTI side portion 104 is changed, similar to Embodiment 1. Also in Embodiment 4, similar to Embodiment 1, the transmittance of DTI20 with respect to near-infrared light is almost zero regardless of the thickness of the DTI side portion 104 and the incident angle. The reflectance of DTI20 with respect to near-infrared light increases for almost all incident angles as the thickness of the DTI side portion 104 increases to 10 nm, 50 nm, and 100 nm. In particular, in the range where the incident angle is 40 degrees or more, as the thickness of the DTI side portion 104 increases, the reflectance of DTI20 with respect to near-infrared light reaches almost 100%.

[0078] FIGS. 12A and 12B show the results of more detailed calculations of the influence of the thickness of the DTI side portion 104 on the reflectance of DTI20 with respect to near-infrared light. FIG. 12A is the calculation result of the reflectance of DTI20 according to the thickness of the DTI side portion 104 with the incident angle fixed at 40 degrees. Referring to FIG. 12A, similar to Embodiment 1, as the thickness of the DTI side portion 104 increases, the reflectance of DTI20 increases and approaches 100%. However, it can be seen that the thickness of the DTI side portion 104 required to reach the same reflectance is larger in Embodiment 4 (when filled with Al) than in Embodiment 1 (when filled with Cu). On the other hand, in Embodiment 4, compared to Embodiment 2 (when filled with Co) and Embodiment 3 (when filled with W), the thickness of the DTI side portion 104 required to reflect the same amount of light is smaller.

[0079] When the incident angle is 40 degrees, in order to make the reflectivity of DTI20 95.0% or more, the thickness of the DTI side portion 104 may be 60 nm or more. In order to make the reflectivity of DTI20 98.0% or more, the thickness of the DTI side portion 104 may be 90 nm or more. In order to make the reflectivity of DTI20 99.0% or more, the thickness of the DTI side portion 104 may be 120 nm or more.

[0080] In order to make the reflectivity of DTI20 99.5% or more, the thickness of the DTI side portion 104 may be 150 nm or more. In order to make the reflectivity of DTI20 99.7% or more, the thickness of the DTI side portion 104 may be 170 nm or more. In order to make the reflectivity of DTI20 99.8% or more, it is preferable that the thickness of the DTI side portion 104 is 180 nm or more. In order to make the reflectivity of DTI20 99.9% or more, the thickness of the DTI side portion 104 may be 210 nm or more.

[0081] Similarly, with the incident angle fixed at 10 degrees, the results of the same calculation as in FIG. 12A are shown in FIG. 12B. In the calculation results of FIG. 12B, when the thickness of the DTI side portion 104 is around 150 nm, the reflectivity of DTI20 reaches a peak.

[0082] When the incident angle is 10 degrees, in order to make the reflectivity of DTI20 95.0% or more, the thickness of the DTI side portion 104 may be 190 nm or less. In order to make the reflectivity of DTI20 94.0% or more, the thickness of the DTI side portion 104 may be 220 nm or less. In order to make the reflectivity of DTI20 93.0% or more, the thickness of the DTI side portion 104 may be 240 nm or less. In order to make the reflectivity of DTI20 92.0% or more, the thickness of the DTI side portion 104 may be 250 nm or less. Note that if the reflectivity of DTI20 is 92.0% or more, a reflectivity 10% or more greater than that of the Al-filled DTI described with reference to FIG. 3C can be achieved. Therefore, the photoelectric conversion device according to this embodiment can sufficiently increase the light sensitivity compared to the photoelectric conversion device described with reference to FIG. 3C.

[0083] According to the above-described Embodiments 1 to 4, it is possible to realize the DTI 20 that increases the reflectance as compared with the conventional metal-filled DTI while making the transmittance of the DTI 20 almost zero.

[0084] In addition, regardless of which of the above metal materials is filled in the DTI interior 103, the reflectance of the DTI 20 is often higher when the incident angle is 40 degrees than when the incident angle is 10 degrees, without greatly depending on the thickness of the DTI side portion 104. For this reason, the thickness of the DTI side portion 104 may be a thickness (approximately 150 nm) such that the reflectance of the DTI 20 with respect to near-infrared light reaches a peak when the incident angle is 10 degrees, regardless of the metal material to be filled.

[0085] <Embodiment 5> The photoelectric conversion system according to this embodiment will be described with reference to FIG. 13. FIG. 13 is a block diagram showing a schematic configuration of the photoelectric conversion system according to this embodiment.

[0086] The photoelectric conversion device (imaging device) described in each of the above embodiments is applicable to various photoelectric conversion systems. Examples of applicable photoelectric conversion systems include digital still cameras, digital camcorders, surveillance cameras, copiers, fax machines, mobile phones, in-vehicle cameras, observation satellites, and the like. Also, a camera module including an optical system such as a lens and an imaging device is included in the photoelectric conversion system. FIG. 13 illustrates a block diagram of a digital still camera as an example of these.

[0087] The photoelectric conversion system illustrated in FIG. 13 has an imaging device 2004 which is an example of a photoelectric conversion device, and a lens 2002 that forms an optical image of a subject on the imaging device 2004. The photoelectric conversion system has a diaphragm 2003 for variably controlling the amount of light passing through the lens 2002, and a barrier 2001 for protecting the lens 2002. The lens 2002 and the diaphragm 2003 are an optical system that condenses light on the imaging device 2004. The imaging device 2004 is a photoelectric conversion device (imaging device) according to any of the above embodiments, and converts the optical image formed by the lens 2002 into an electrical signal.

[0088] The photoelectric conversion system also includes a signal processing unit 2007, which is an image generation unit that generates an image by processing the output signal output from the imaging device 2004. The signal processing unit 2007 performs operations such as various corrections and compressions as necessary to output image data. The signal processing unit 2007 may be formed on the semiconductor substrate on which the imaging device 2004 is provided, or may be formed on a semiconductor substrate different from the imaging device 2004. Further, the imaging device 2004 and the signal processing unit 2007 may be formed on the same semiconductor substrate.

[0089] The photoelectric conversion system further includes a memory unit 2010 for temporarily storing image data, and an external interface unit (external I / F unit) 2013 for communicating with an external computer or the like. Additionally, the photoelectric conversion system includes a recording medium 2012 such as a semiconductor memory for recording or reading imaging data, and a recording medium control interface unit (recording medium control I / F unit) 2011 for recording or reading from the recording medium 2012. Note that the recording medium 2012 may be built into the photoelectric conversion system or may be detachable.

[0090] Furthermore, the photoelectric conversion system includes an overall control and arithmetic unit 2009 for performing various operations and controlling the entire digital still camera, and a timing generation unit 2008 for outputting various timing signals to the imaging device 2004 and the signal processing unit 2007. Here, the timing signals and the like may be input from the outside, and the photoelectric conversion system may have at least the imaging device 2004 and the signal processing unit 2007 that processes the output signal output from the imaging device 2004.

[0091] The imaging device 2004 outputs an imaging signal to the signal processing unit 2007. The signal processing unit 2007 performs predetermined signal processing on the imaging signal output from the imaging device 2004 and outputs image data. The signal processing unit 2007 generates an image using the imaging signal.

[0092] Thus, according to this embodiment, a photoelectric conversion system applying the photoelectric conversion device (imaging device) of any of the above embodiments can be realized.

[0093] <Embodiment 6> The photoelectric conversion system and the moving body of this embodiment will be described with reference to FIGS. 14A and 14B. FIG. 14 is a diagram showing the configuration of the photoelectric conversion system and the moving body of this embodiment.

[0094] FIG. 14A shows an example of a photoelectric conversion system related to an in-vehicle camera. The photoelectric conversion system 1300 includes an imaging device 1310. The imaging device 1310 is the photoelectric conversion device (imaging device) described in any of the above embodiments. The photoelectric conversion system 1300 has an image processing unit 1312 that performs image processing on a plurality of image data acquired by the imaging device 1310. Further, the photoelectric conversion system 1300 has a parallax acquisition unit 1314 that calculates parallax (phase difference of parallax images) from a plurality of image data acquired by the photoelectric conversion system 1300. Further, the photoelectric conversion system 1300 has a distance acquisition unit 1316 that calculates the distance to an object based on the calculated parallax, and a collision determination unit 1318 that determines whether there is a possibility of collision based on the calculated distance. Here, the parallax acquisition unit 1314 and the distance acquisition unit 1316 are examples of distance information acquisition means for acquiring distance information to an object. That is, the distance information is information related to parallax, defocus amount, distance to an object, and the like. The collision determination unit 1318 may determine the possibility of collision using any of these distance information. The distance information acquisition means may be realized by dedicatedly designed hardware, or may be realized by a software module. Further, it may be realized by an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or the like, or may be realized by a combination of these.

[0095] The photoelectric conversion system 1300 is connected to a vehicle information acquisition device 1320, and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. The photoelectric conversion system 1300 is also connected to a control ECU 1330, which is a control device (control unit) that outputs a control signal to generate a braking force for the vehicle based on the judgment result of the collision judgment unit 1318. The photoelectric conversion system 1300 is also connected to an alarm device 1340 that issues an alarm to the driver based on the judgment result of the collision judgment unit 1318. For example, when the judgment result of the collision judgment unit 1318 indicates that there is a high possibility of a collision, the control ECU 1330 performs vehicle control to avoid a collision and reduce damage by applying the brakes, releasing the accelerator, suppressing engine output, etc. The alarm device 1340 warns the user by sounding an alarm, displaying alarm information on a screen of a car navigation system, etc., or vibrating a seat belt or steering wheel.

[0096] In this embodiment, the surroundings of the vehicle, for example, the front or rear, are photographed by a photoelectric conversion system 1300. 14B shows the photoelectric conversion system when capturing an image of the area in front of the vehicle (imaging range 1350). A vehicle information acquisition device 1320 sends an instruction to the photoelectric conversion system 1300 or the imaging device 1310. With this configuration, the accuracy of distance measurement can be further improved.

[0097] Although the above describes an example of control to prevent collision with other vehicles, the present invention can also be applied to control of automatic driving by following other vehicles, control of automatic driving to prevent deviation from lanes, etc. Furthermore, the photoelectric conversion system is not limited to vehicles such as the vehicle itself, but can be applied to moving bodies (moving devices) such as ships, aircraft, and industrial robots. In addition, the present invention can be applied not only to moving bodies, but also to a wide range of devices that use object recognition, such as intelligent transport systems (ITS).

[0098] [Modified embodiment] The present invention is not limited to the above-described embodiments and can be variously modified. For example, examples of adding a part of the configuration of any one of the embodiments to other embodiments or replacing a part of the configuration with that of other embodiments are also included in the embodiments of the present invention.

[0099] Moreover, the photoelectric conversion systems shown in Embodiment 5 and Embodiment 6 are examples of photoelectric conversion systems to which the photoelectric conversion device can be applied, and the photoelectric conversion systems applicable to the photoelectric conversion device of the present invention are not limited to the configurations shown in FIGS. 13 and 14A and 14B.

[0100] <Embodiment 7: ToF System> The photoelectric conversion system of this embodiment will be described with reference to FIG. 15. FIG. 15 is a block diagram showing a configuration example of a distance image sensor which is the photoelectric conversion system of this embodiment.

[0101] As shown in FIG. 15, the distance image sensor 1401 includes an optical system 1402, a photoelectric conversion device 1403, an image processing circuit 1404, a monitor 1405, and a memory 1406. Then, the distance image sensor 1401 can obtain a distance image corresponding to the distance to the subject by receiving the light (modulated light or pulsed light) projected from the light source device 1411 toward the subject and reflected by the surface of the subject.

[0102] The optical system 1402 is configured to have one or a plurality of lenses, guide the image light (incident light) from the subject to the photoelectric conversion device 1403, and form an image on the light receiving surface (sensor unit) of the photoelectric conversion device 1403.

[0103] As the photoelectric conversion device 1403, the photoelectric conversion devices of the above-described embodiments are applied, and a distance signal indicating the distance obtained from the light receiving signal output from the photoelectric conversion device 1403 is supplied to the image processing circuit 1404.

[0104] The image processing circuit 1404 performs image processing to construct a distance image based on the distance signal supplied from the photoelectric conversion device 1403. Then, the distance image (image data) obtained by the image processing is supplied to the monitor 1405 for display or supplied to the memory 1406 for storage (recording).

[0105] In the distance image sensor 1401 configured as described above, by applying the photoelectric conversion device described above, it is possible to obtain, for example, a more accurate distance image as the characteristics of the pixels are improved.

[0106] <Embodiment 8: Endoscope> The photoelectric conversion system of this embodiment will be described with reference to FIG. 16. FIG. 16 is a diagram showing an example of the schematic configuration of an endoscope surgical system which is the photoelectric conversion system of this embodiment. FIG. 16 is a diagram showing an example of the schematic configuration of an endoscope surgical system which is the photoelectric conversion system of this embodiment.

[0107] In FIG. 16, a state where a surgeon (doctor) 1131 is performing surgery on a patient 1132 on a patient bed 1133 using an endoscope surgical system 1030 is illustrated. As shown, the endoscope surgical system 1030 is composed of an endoscope 1100, a surgical instrument 1110, and a cart 1134 on which various devices for endoscopic surgery are mounted.

[0108] The endoscope 1100 is composed of a lens barrel 1101 whose tip region of a predetermined length is inserted into the body cavity of the patient 1132, and a camera head 1102 connected to the base end of the lens barrel 1101. In the illustrated example, an endoscope 1100 configured as a so-called rigid endoscope having a rigid lens barrel 1101 is shown, but the endoscope 1100 may be configured as a so-called flexible endoscope having a flexible lens barrel.

[0109] At the tip of the lens barrel 1101, an opening into which an objective lens is fitted is provided. A light source device 1203 is connected to the endoscope 1100, and the light generated by the light source device 1203 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 1101, and is irradiated toward an observation target in the body cavity of the patient 1132 through the objective lens. Note that the endoscope 1100 may be a forward-viewing endoscope, or may be an oblique-viewing endoscope or a side-viewing endoscope.

[0110] An optical system and a photoelectric conversion device are provided inside the camera head 1102, and the reflected light (observation light) from the observation target is condensed onto the photoelectric conversion device by the optical system. The observation light is photoelectrically converted by the photoelectric conversion device, and an electrical signal corresponding to the observation light, that is, an image signal corresponding to the observation image, is generated. As the photoelectric conversion device, the photoelectric conversion device (imaging device) described in each of the above embodiments can be used. The image signal is transmitted as RAW data to a camera control unit (CCU) 1135.

[0111] The CCU 1135 is composed of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operations of the endoscope 1100 and the display device 1136. Further, the CCU 1135 receives an image signal from the camera head 1102, and performs various image processes for displaying an image based on the image signal, such as development processing (demosaicing processing), on the image signal.

[0112] The display device 1136 displays an image based on the image signal that has been subjected to image processing by the CCU 1135 under the control of the CCU 1135.

[0113] The light source device 1203 is composed of a light source such as an LED (Light Emitting Diode), and supplies irradiation light for photographing the surgical site or the like to the endoscope 1100.

[0114] The input device 1137 is an input interface for the endoscopic surgery system 1030. The user can input various information and give instructions to the endoscopic surgery system 1030 via the input device 1137.

[0115] The treatment instrument control device 1138 controls the driving of the energy treatment instrument 1112 for tissue cauterization, incision, or blood vessel sealing.

[0116] The light source device 1203 that supplies irradiation light when photographing the surgical site with the endoscope 1100 can be composed of, for example, an LED, a laser light source, or a white light source composed of a combination thereof. When a white light source is configured by combining RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision. Therefore, the white balance of the captured image can be adjusted in the light source device 1203. Also, in this case, the laser light from each of the RGB laser light sources is irradiated to the observation target in a time-division manner, and by controlling the driving of the imaging element of the camera head 1102 in synchronization with the irradiation timing, it is also possible to capture images corresponding to each of RGB in a time-division manner. According to this method, a color image can be obtained without providing a color filter on the imaging element.

[0117] Also, the driving of the light source device 1203 may be controlled so that the intensity of the output light is changed every predetermined time. By controlling the driving of the imaging element of the camera head 1102 in synchronization with the timing of the change in the intensity of the light and acquiring images in a time-division manner and synthesizing the images, it is possible to generate a so-called high-dynamic range image without black crush and white clip.

[0118] Further, the light source device 1203 may be configured to supply light in a predetermined wavelength band corresponding to special light observation. In special light observation, for example, the wavelength dependence of light absorption in body tissue is utilized. Specifically, by irradiating narrow-band light as compared with the irradiation light (i.e., white light) during normal observation, a predetermined tissue such as blood vessels in the mucosal surface layer is photographed with high contrast. Alternatively, in special light observation, fluorescence observation may be performed to obtain an image by fluorescence generated by irradiating excitation light. In fluorescence observation, excitation light is irradiated onto body tissue and fluorescence from the body tissue is observed, or a reagent such as indocyanine green (ICG) is locally injected into the body tissue and excitation light corresponding to the fluorescence wavelength of the reagent is irradiated onto the body tissue to obtain a fluorescence image. The light source device 1203 can be configured to supply such narrow-band light and / or excitation light corresponding to special light observation.

[0119] <Embodiment 9: Smart Glasses> The photoelectric conversion system of this embodiment will be described with reference to FIGS. 17A and 17B. FIG. 17A illustrates glasses 1600 (smart glasses), which are the photoelectric conversion system of this embodiment. The glasses 1600 have a photoelectric conversion device 1602. The photoelectric conversion device 1602 is the photoelectric conversion device (imaging device) described in each of the above embodiments. Further, a display device including a light emitting device such as an OLED or an LED may be provided on the back side of the lens 1601. The photoelectric conversion device 1602 may be one or a plurality. Also, a plurality of types of photoelectric conversion devices may be combined and used. The arrangement position of the photoelectric conversion device 1602 is not limited to FIG. 17A.

[0120] The glasses 1600 further include a control device 1603. The control device 1603 functions as a power source that supplies power to the photoelectric conversion device 1602 and the above display device. Further, the control device 1603 controls the operations of the photoelectric conversion device 1602 and the display device. An optical system for condensing light onto the photoelectric conversion device 1602 is formed in the lens 1601.

[0121] FIG. 17B illustrates glasses 1610 (smart glasses) according to one application example. The glasses 1610 have a control device 1612. The control device 1612 is equipped with a photoelectric conversion device corresponding to the photoelectric conversion device 1602 and a display device. In the lens 1611, an optical system for projecting the light emission from the photoelectric conversion device and the display device within the control device 1612 is formed, and an image is projected onto the lens 1611. The control device 1612 functions as a power source for supplying power to the photoelectric conversion device and the display device, and controls the operations of the photoelectric conversion device and the display device. The control device may have a gaze detection unit for detecting the wearer's gaze. Infrared light may be used for gaze detection. The infrared light emitting unit emits infrared light toward the eyeball of the user who is gazing at the display image. The imaging unit having a light receiving element detects the reflected light of the emitted infrared light from the eyeball, thereby obtaining an imaging image of the eyeball. By having a reducing means for reducing the light from the infrared light emitting unit to the display unit in a plan view, a decrease in image quality is reduced.

[0122] The user's gaze with respect to the display image is detected from the imaging image of the eyeball obtained by imaging infrared light. Any known method can be applied to gaze detection using the imaging image of the eyeball. As an example, a gaze detection method based on the Purkinje image by reflection of the irradiation light on the cornea can be used.

[0123] More specifically, a gaze detection process based on the pupil corneal reflection method is performed. Using the pupil corneal reflection method, a gaze vector representing the orientation (rotation angle) of the eyeball is calculated based on the image of the pupil and the Purkinje image included in the imaging image of the eyeball, thereby detecting the user's gaze.

[0124] The display device of the present embodiment has a photoelectric conversion device having a light receiving element, and may control the display image of the display device based on the user's gaze information from the photoelectric conversion device.

[0125] Specifically, the display device determines, based on the line-of-sight information, a first field of view area that the user is gazing at and a second field of view area outside the first field of view area. The first field of view area and the second field of view area may be determined by the control device of the display device, or may be areas received from an external control device that has made the determination. In the display area of the display device, the display resolution of the first field of view area may be controlled to be higher than that of the second field of view area. That is, the resolution of the second field of view area may be made lower than that of the first field of view area.

[0126] Also, the display area has a first display area and a second display area different from the first display area, and based on the line-of-sight information, an area with a higher priority may be determined from the first display area and the second display area. The first field of view area and the second field of view area may be determined by the control device of the display device, or may be areas received from an external control device that has made the determination. The resolution of the area with a higher priority may be controlled to be higher than that of the areas other than the area with a higher priority. That is, the resolution of the area with a relatively lower priority may be made lower.

[0127] Note that AI may be used to determine the first field of view area or the area with a higher priority. AI may be a model configured to estimate the angle of the line of sight and the distance to the object at the tip of the line of sight from an eye image using the eye image and the direction in which the eye in the image is actually looking as teacher data. The AI program may be possessed by the display device, the photoelectric conversion device, or an external device. When it is possessed by an external device, it is transmitted to the display device via communication.

[0128] When performing display control based on visual recognition detection, it is preferably applicable to smart glasses that further have a photoelectric conversion device for imaging the outside. The smart glasses can display the imaged external information in real time.

[0129] Note that each of the above embodiments merely shows examples of implementation in practicing the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. That is, the present invention can be implemented in various forms without departing from its technical idea or its main features.

[0130] Note that each functional part of each of the above embodiments may be individual hardware, or may not be. The functions of two or more functional parts may be realized by common hardware. Each of the multiple functions of one functional part may be realized by individual hardware. Two or more functions of one functional part may be realized by common hardware. Also, each functional part may be realized by hardware such as an ASIC, FPGA, DSP, etc., or may not be. For example, the device may have a processor and a memory (storage medium) in which a control program is stored. And the functions of at least some of the functional parts of the device may be realized by the processor reading out and executing the control program from the memory Thereby.

[0131] (Other Embodiments) The present invention can also be realized by supplying a program that realizes one or more functions of the above embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (for example, an ASIC) that realizes one or more functions.

Explanation of Reference Numerals

[0132] 10: Semiconductor layer, 20: DTI 100: Silicon, 103: Inside DTI, 104: Side part of DTI

Claims

1. A photoelectric conversion device having a semiconductor layer formed of silicon, wherein a pixel separation portion for separating each pixel is formed inside the semiconductor layer, the pixel separation portion has a metal filling portion and a dielectric film provided on a side portion of the metal filling portion, light having a wavelength of 750 nm or more and 2500 nm or less is incident on the pixel, the material of the metal filling portion is copper, the material of the dielectric film is silicon dioxide, the thickness of the dielectric film surrounding the side portion of the metal filling portion is 50 nm or more and 270 nm or less, A photoelectric conversion device characterized by the above.

2. The thickness of the dielectric film is 70 nm or more, A photoelectric conversion device according to claim 1, characterized by the above.

3. The thickness of the dielectric film is 110 nm or more, A photoelectric conversion device according to claim 1 or 2, characterized by the above.

4. The thickness of the dielectric film is 130 nm or more, A photoelectric conversion device according to any one of claims 1 to 3, characterized by the above.

5. The thickness of the dielectric film is 190 nm or less, A photoelectric conversion device according to any one of claims 1 to 4, characterized by the above.

6. A photoelectric conversion device having a semiconductor layer formed of silicon, wherein a pixel separation portion for separating each pixel is formed inside the semiconductor layer, the pixel separation portion has a metal filling portion and a dielectric film provided on a side portion of the metal filling portion, light having a wavelength of 750 nm or more and 2500 nm or less is incident on the pixel, The material of the metal filling portion is tungsten, The material of the dielectric film is silicon dioxide, The thickness of the dielectric film surrounding the side portion of the metal filling portion is 130 nm or more and 250 nm or less, A photoelectric conversion device characterized by the above.

7. The thickness of the dielectric film is 170 nm or more, A photoelectric conversion device according to claim 6, characterized by the above.

8. The thickness of the dielectric film is 200 nm or more, A photoelectric conversion device according to claim 6 or 7, characterized by the above.

9. The thickness of the dielectric film is 200 nm or less, A photoelectric conversion device according to any one of claims 6 to 8, characterized by the above.

10. A photoelectric conversion device having a semiconductor layer formed of silicon, Inside the semiconductor layer, a pixel separation portion for separating each pixel is formed, The pixel separation portion has a metal filling portion and a dielectric film provided on a side portion of the metal filling portion, Light having a wavelength of 750 nm or more and 2500 nm or less is incident on the pixel, The material of the metal filling portion is cobalt, The material of the dielectric film is silicon dioxide, The thickness of the dielectric film surrounding the side portion of the metal filling portion is 110 nm or more and 270 nm or less, A photoelectric conversion device characterized by the above.

11. The thickness of the dielectric film is 170 nm or more, A photoelectric conversion device according to claim 10, characterized by the above.

12. The thickness of the dielectric film is 210 nm or less, The photoelectric conversion device according to claim 10 or 11, characterized in that...

13. A photoelectric conversion device having a semiconductor layer formed of silicon, wherein a pixel separation part for separating each pixel is formed inside the semiconductor layer, the pixel separation part has a metal filling part and a dielectric film provided on a side part of the metal filling part, light having a wavelength of 750 nm or more and 2500 nm or less is incident on the pixel, the material of the metal filling part is aluminum, the material of the dielectric film is silicon dioxide, the thickness of the dielectric film surrounding the side part of the metal filling part is 60 nm or more and 250 nm or less, A photoelectric conversion device, characterized in that...

14. the thickness of the dielectric film is 150 nm or more, The photoelectric conversion device according to claim 13, characterized in that...

15. the thickness of the dielectric film is 190 nm or less, The photoelectric conversion device according to claim 13 or 14, characterized in that...

16. the thickness of the dielectric film is approximately 150 nm, The photoelectric conversion device according to claim 1, 6, 10 or 13, characterized in that...

17. the photoelectric conversion device is a back-illuminated solid-state imaging device, The photoelectric conversion device according to any one of claims 1 to 16, characterized in that...

18. a periodic uneven structure part for diffracting light is provided on the light incident surface side of the semiconductor layer, The photoelectric conversion device according to any one of claims 1 to 17, characterized in that...

19. A metal wiring of a wiring layer of the photoelectric conversion device is provided directly below the periodic uneven structure part. The photoelectric conversion device according to claim 18, characterized in that...

20. The semiconductor layer and the dielectric film are in contact with each other. The photoelectric conversion device according to any one of claims 1 to 19, characterized in that...

21. Each pixel has an avalanche photodiode. The photoelectric conversion device according to any one of claims 1 to 20, characterized in that...

22. A photoelectric conversion device according to any one of claims 1 to 21, a signal processing unit that generates an image using the signal output by the photoelectric conversion device, A photoelectric conversion system, characterized by comprising the above.

23. A moving body equipped with a photoelectric conversion device according to any one of claims 1 to 21, characterized by having a control unit that controls the movement of the moving body using the signal output by the photoelectric conversion device.

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