CN116568991A - Light detection device and distance measuring device - Google Patents

Light detection device and distance measuring device Download PDF

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Publication number
CN116568991A
CN116568991A CN202180080131.3A CN202180080131A CN116568991A CN 116568991 A CN116568991 A CN 116568991A CN 202180080131 A CN202180080131 A CN 202180080131A CN 116568991 A CN116568991 A CN 116568991A
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CN
China
Prior art keywords
light receiving
light
semiconductor substrate
semiconductor
multiplication
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CN202180080131.3A
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Chinese (zh)
Inventor
铃木淳贵
大竹悠介
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Sony Semiconductor Solutions Corp
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Sony Semiconductor Solutions Corp
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Publication of CN116568991A publication Critical patent/CN116568991A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C3/00—Measuring distances in line of sight; Optical rangefinders
    • G01C3/02—Details
    • G01C3/06—Use of electric means to obtain final indication
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
    • H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by potential barriers, e.g. phototransistors
    • H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
    • H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier
    • H01L31/107—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier the potential barrier working in avalanche mode, e.g. avalanche photodiodes

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Light Receiving Elements (AREA)
  • Solid State Image Pick-Up Elements (AREA)
  • Measurement Of Optical Distance (AREA)

Abstract

A light detection device according to an embodiment of the present disclosure includes: a semiconductor substrate having a first surface and a second surface which face each other, and having a pixel array portion in which a plurality of pixels are arranged in an array; a light receiving portion buried in the first surface side of the semiconductor substrate for each pixel, the light receiving portion being formed of a semiconductor having a narrower band gap than the semiconductor substrate, and generating carriers corresponding to the amount of light received by photoelectric conversion; and a multiplication unit provided near the surface of the light receiving unit, the surface being substantially the same as the first surface of the semiconductor substrate, the multiplication unit being formed of a semiconductor having a narrower band gap than the semiconductor substrate, and performing avalanche multiplication on carriers generated in the light receiving unit.

Description

Light detection device and distance measuring device
Technical Field
The present disclosure relates to a light detection device using an avalanche photodiode, for example, and a distance measuring device provided with the light detection device.
Background
For example, patent document 1 discloses a photodetector as follows: an avalanche photodiode is provided for each pixel, and a semiconductor region surrounding the avalanche photodiode is provided to separate adjacent pixels.
Prior art literature
Patent literature
Patent document 1: international publication No. 2018/074530
Disclosure of Invention
However, in the light detection device constituting the distance measuring device, it is required to reduce the generation of dark current.
It is desirable to provide a light detection device and a distance measuring device that can reduce the generation of dark current.
A light detection device according to an embodiment of the present disclosure includes: a semiconductor substrate having a first surface and a second surface which face each other, and having a pixel array portion in which a plurality of pixels are arranged in an array; a light receiving portion buried in the first surface side of the semiconductor substrate for each pixel, the light receiving portion being formed of a semiconductor having a narrower band gap than the semiconductor substrate, and generating carriers corresponding to the amount of light received by photoelectric conversion; and a multiplication unit provided near the surface of the light receiving unit, the surface being substantially the same as the first surface of the semiconductor substrate, the multiplication unit being formed of a semiconductor having a narrower band gap than the semiconductor substrate, and performing avalanche multiplication on carriers generated in the light receiving unit.
The distance measuring device according to an embodiment of the present disclosure includes an optical system, a light detection device, and a signal processing circuit for calculating a distance to a measurement object from an output signal of the light detection device, and includes the light detection device according to the embodiment of the present disclosure as the light detection device.
In the light detection device according to one embodiment of the present disclosure and the distance measuring device according to one embodiment, the light receiving portion and the multiplication portion are formed using semiconductors having narrower band gaps than the semiconductor substrate, respectively, so that lattice mismatch at an interface between the light receiving portion and the multiplication portion is alleviated, the light receiving portion is buried in a first surface side of the semiconductor substrate having a first surface and a second surface which are opposed to each other, and the multiplication portion is provided in the vicinity of a surface of the light receiving portion having substantially the same surface as the first surface of the semiconductor substrate.
Drawings
Fig. 1 is a schematic sectional view showing an example of the configuration of a light detection device according to an embodiment of the present disclosure.
Fig. 2 is a schematic plan view showing an example of the configuration of the pixel array section of the photodetector shown in fig. 1.
Fig. 3 is a block diagram showing an example of the schematic configuration of the light detection device shown in fig. 1.
Fig. 4 is an example of an equivalent circuit diagram of a unit pixel of the photodetecting device shown in fig. 1.
Fig. 5A is a schematic plan view showing another example of a plan view configuration of a unit pixel of the light detection device shown in fig. 1.
Fig. 5B is a schematic plan view showing another example of a plan view configuration of a unit pixel of the light detection device shown in fig. 1.
Fig. 5C is a schematic plan view showing another example of a plan view configuration of a unit pixel of the photodetecting device shown in fig. 1.
Fig. 6 is a schematic cross-sectional view showing an example of the configuration of the photodetection device according to modification 1 of the present disclosure.
Fig. 7 is a schematic cross-sectional view showing another example of the configuration of the photodetection device according to modification 1 of the present disclosure.
Fig. 8 is a schematic cross-sectional view showing another example of the configuration of the photodetection device according to modification 1 of the present disclosure.
Fig. 9 is a schematic cross-sectional view showing an example of the configuration of the photodetection device according to modification 2 of the present disclosure.
Fig. 10 is a schematic cross-sectional view showing an example of the configuration of a light detection device according to modification 3 of the present disclosure.
Fig. 11 is a schematic sectional view showing an example of the configuration of a light detection device according to modification 4 of the present disclosure.
Fig. 12 is a schematic cross-sectional view showing an example of the configuration of the photodetection device according to modification 5 of the present disclosure.
Fig. 13 is a schematic cross-sectional view showing an example of the configuration of a light detection device according to modification 6 of the present disclosure.
Fig. 14 is a schematic cross-sectional view showing another example of the configuration of the photodetection device according to modification 6 of the present disclosure.
Fig. 15 is a schematic cross-sectional view showing an example of the configuration of a light detection device according to modification 7 of the present disclosure.
Fig. 16 is a schematic cross-sectional view showing an example of the configuration of a light detection device according to modification 8 of the present disclosure.
Fig. 17 is a schematic cross-sectional view showing an example of the configuration of a light detection device according to modification 9 of the present disclosure.
Fig. 18 is a schematic cross-sectional view showing an example of the configuration of the light detection device according to modification 10 of the present disclosure.
Fig. 19 is a schematic cross-sectional view showing another example of the configuration of the light detection device according to modification 10 of the present disclosure.
Fig. 20 is a functional block diagram showing an example of an electronic device using the light detection device shown in fig. 1 and the like.
Fig. 21 is a block diagram showing an example of a schematic configuration of a vehicle control system.
Fig. 22 is an explanatory diagram showing an example of installation positions of the outside-vehicle information detection unit and the imaging unit.
Detailed Description
Embodiments in the present disclosure will be described in detail below with reference to the accompanying drawings. The following description is one specific example of the present disclosure, and the present disclosure is not limited to the following modes. In the present disclosure, the arrangement, dimensions, and dimensional ratios of the constituent elements shown in the drawings are not limited to these. The procedure of the description is as follows.
1. Embodiments (photodetecting device in which the photodetecting portion and the multiplication portion are made of a material having a narrower band gap than the Si substrate)
1-1 construction of light detection device
1-2 method for manufacturing light detection device
1-3 action/Effect
2. Modification examples
Modification 1 (example in which an n-type diffusion region is provided at the outer edge of the light receiving portion)
Modification 2-2 (example in which a guard ring is provided around the multiplication section)
2-3 modification 3 (example in which contact electrodes are provided on the light receiving portion and the multiplying portion, respectively)
2-4 modification 4 (example in which the light receiving section is provided with a multiplication section)
2-5 modification 5 (example in which the side of the multiplication section is an inclined surface)
2-6 modification 6 (example in which the multiplication section is reduced)
2-7 modification 7 (example in which a buffer layer is provided between the semiconductor substrate and the light receiving portion)
2-8 modification 8 (example in which a light reflecting layer is provided at a position of the multilayer wiring layer facing the light receiving element)
2-9 modification 9 (example in which the concave-convex structure is provided on the light incident surface of the semiconductor substrate)
2-10 modification 10 (other examples of the constitution of the pixel separation section)
3. Application example
4. Application example
1. Description of the embodiments
Fig. 1 schematically shows an example of a cross-sectional configuration of a light detection device (light detection device 1) according to an embodiment of the present disclosure. Fig. 2 schematically illustrates an example of a plan view configuration of the pixel array section 100A of the photodetector 1 illustrated in fig. 1. Fig. 3 is a block diagram showing a schematic configuration of the light detection device 1 shown in fig. 1, and fig. 4 shows an example of an equivalent circuit of the unit pixel P of the light detection device 1 shown in fig. 1. The light detection device 1 is applied to, for example, a distance image sensor (hereinafter described distance image device 1000, see fig. 20) and an image sensor (image sensor) that measure a distance by the ToF (Time of Flight) method.
1-1 construction of light detection device
The photodetector 1 includes, for example, a pixel array section 100A in which a plurality of unit pixels P are arranged in an array in the row direction and the column direction. As shown in fig. 3, the light detection device 1 has a pixel array section 100A and has a bias voltage applying section 110. The bias voltage applying section 110 applies a bias voltage to each unit pixel P of the pixel array section 100A. In this embodiment, a case where holes are read out as signal charges will be described.
As shown in fig. 4, the unit pixel P includes, for example, a light receiving element 12, an inverter 120, N-type MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistor: metal Oxide semiconductor field effect transistors) 130, 140, a P-type MOSFET150, and a buffer circuit 160.
The light receiving element 12 converts incident light into an electrical signal by photoelectric conversion and outputs the electrical signal. Incidentally, the light receiving element 12 converts incident light (photons) into an electrical signal by photoelectric conversion, and outputs a pulse corresponding to the incidence of the photons. The light receiving element 12 is, for example, a SPAD element having a characteristic that, when a large positive voltage generating avalanche multiplication is applied to the cathode, for example, electrons generated in response to incidence of one photon generate avalanche multiplication and flow a large current. In the light receiving element 12, for example, a cathode is connected to a power supply of a voltage Vop corresponding to a breakdown voltage of the light receiving element 12, and an anode is connected to an N-type MOSFET130 as a current source.
The source of the N-type MOSFET130 is connected to the ground potential GND. Here, the voltage Vop is a voltage obtained by adding the excess bias voltage Ve to the voltage Vbd which is the breakdown voltage of the light receiving element 12. The gate of the N-type MOSFET130 receives a reference voltage Vref. The N-type MOSFET130 is a current source that outputs a current corresponding to the ground potential GND and the reference voltage Vref from the drain.
The anode of the light receiving element 12 is connected to the drain of the N-type MOSFET130, and the voltage Van taken out from the connection point thereof is input to the inverter 120. The inverter 120 determines the input voltage Van, and outputs a signal Vinv inverted every time the voltage Van exceeds the threshold voltage Vth in the positive direction or the negative direction, for example. The signal Vinv output from the inverter 120 is output as a signal Vpls via the buffer circuit 160, for example.
The junction of the anode of the light receiving element 12 and the drain of the N-type MOSFET130 is also connected to the drain of the N-type MOSFET140 and the drain of the P-type MOSFET 150. In the P-type MOSFET150, a source is connected to a power supply voltage VDD corresponding to the excessive bias voltage Ve, and a signal STBY is input to a gate. The signal STBY turns on between the source and the drain of the P-type MOSFET150 in the low state, and the voltage Van of the anode of the light receiving element 12 is forcibly changed to the voltage VDD. Thereby, the voltage V between the cathode and the anode of the light receiving element 12 CTH-AN Becomes the voltage Vbd.
The source of the N-type MOSFET140 is connected to the ground potential GND. The signal Vinv output from the inverter 120 is input as a control signal Vctrl to the gate of the N-type MOSFET 140. The N-type MOSFET140 is turned on when the signal Vinv, i.e., the control signal Vctrl is in a high state, and connects the anode of the light receiving element 12 to the ground potential GND.
The light detection device 1 is a so-called back-side illumination type light detection device in which, for example, a logic substrate 20 is laminated on the front surface side of a sensor substrate 10 (for example, the front surface (first surface 11S 1) side of a semiconductor substrate 11 constituting the sensor substrate 10), and light is received from the back surface side of the sensor substrate 10 (for example, the back surface (second surface 11S 2) side of the semiconductor substrate 11 constituting the sensor substrate 10). The photodetection device 1 of the present embodiment is formed by embedding a light receiving portion 13 constituting a light receiving element 12 in the first surface 11S1 side of a semiconductor substrate 11, and is formed by forming a multiplication portion 14 constituting the light receiving element 12 together with the light receiving portion 13 in the vicinity of the surface 13S1 of the light receiving portion 13, specifically, in the surface 13S1 inside the light receiving portion 13, and by using semiconductors having band gaps narrower than those of the semiconductor substrate 11.
The sensor substrate 10 includes, for example, a semiconductor substrate 11 composed of a silicon substrate and a multilayer wiring layer 18. The semiconductor substrate 11 has a first surface 11S1 and a second surface 11S2 facing each other, and the light receiving element 12 is buried in the first surface 11S1 for each unit pixel P.
As described above, the light receiving element 12 has a multiplication region (avalanche multiplication region) in which carriers are avalanche-multiplied by a high electric field region, and is, for example, a SPAD element in which an avalanche multiplication region (depletion layer) is formed by applying a large positive voltage to a cathode, and electrons generated by incidence of one photon can be avalanche-multiplied.
The light receiving element 12 includes, for example, a light receiving section 13 and a multiplication section 14. As described above, the light receiving portion 13 and the multiplication portion 14 are each formed of a semiconductor having a narrower band gap than the semiconductor substrate 11. Specifically, the light receiving portion 13 and the multiplication portion 14 are formed using germanium (Ge) or a compound semiconductor of silicon (Si) and germanium (Ge) (for example, silicon germanium (SiGe)).
The light receiving portion 13 has a photoelectric conversion function of absorbing light incident from the second surface 11S2 side of the semiconductor substrate 11 and generating carriers corresponding to the amount of light received. The light receiving portion 13 is formed embedded in the first surface 11S1 side of the semiconductor substrate 11, for example, and the surface 13S1 thereof is formed substantially on the same surface as the first surface 11S1 of the semiconductor substrate 11, for example. The light receiving portion 13 is constituted by, for example, an n-type semiconductor region (n) 131 whose impurity concentration is controlled to be n-type. The carriers (electrons) generated in the light receiving portion 13 are transported to the multiplication portion 14 by the potential gradient.
The multiplier section 14 performs avalanche multiplication on carriers (electrons) generated in the light receiving section 13. The multiplication section 14 is formed of, for example, a p-type semiconductor region (p + ) 141.
An n-type contact electrode 15 electrically connected to the cathode is further provided on the surface 13S1 of the light receiving portion 13. The n-type contact electrode 15 is formed of, for example, an n-type semiconductor region (n ++ ) 151 are formed continuously around the multiplier section 14 at predetermined intervals in a plan view, for example. A p-type contact electrode 16 electrically connected to the anode is provided on the surface 14S1 of the multiplication section 14. The p-type contact electrode 16 is formed of, for example, a p-type semiconductor region (p ++ ) 161 is formed, for example, in the approximate center of the multiplier section 14 in plan view.
In the light receiving element 12, an avalanche multiplication region 12X is formed at a junction between the n-type semiconductor region 131 constituting the light receiving portion 13 and the p-type semiconductor region 141 constituting the multiplication portion 14. The avalanche multiplication region 12X is formed in the n-type semiconductor region 131 and the p-type semiconductor region by a large positive voltage applied to the cathodeA high electric field region (depletion layer) at the boundary surface of the semiconductor region 141. In the avalanche multiplication region 12X, electrons (e) generated by one photon incident on the light receiving element 12 - ) Multiplication.
In fig. 2, an example is shown in which the multiplication section 14 and the p-type contact electrode 16 having a substantially rectangular shape and the n-type contact electrode 15 having a frame shape having a substantially rectangular outer diameter are provided around the multiplication section 14 on the inner side of the light receiving section 13 having a substantially rectangular planar shape, but the shapes of the multiplication section 14, the n-type contact electrode 15, and the p-type contact electrode 16 are not limited thereto. For example, as shown in fig. 5A, the multiplier section 14 and the p-type contact electrode 16 may have a polygonal shape other than a rectangular shape. In particular, when the pixel size is small, it is preferable that the multiplication section 14 and the p-type contact electrode 16 are circular from the viewpoint of fringing electric field alleviation in the lateral direction (for example, XY plane direction), as shown in fig. 5B. In addition, in the case where the pixel size is small, as shown in fig. 5C, the n-type contact electrode 15 may be intermittently provided at four corners of the light receiving section 13. Thereby, unintended breakdown in areas outside the multiplication 14 is reduced.
A pixel separation section 17 is also provided on the semiconductor substrate 11. The pixel separation unit 17 electrically and/or optically separates adjacent unit pixels P, and is provided in a grid shape in the pixel array unit 100A, for example. The pixel separation portion 17 is formed of, for example, a light shielding film 17A extending between the first surface 11S1 and the second surface 11S2 of the semiconductor substrate 11, and an insulating film 17B provided between the light shielding film 17A and the semiconductor substrate 11. The light shielding film 17A is formed using, for example, a conductive material having light shielding properties. Examples of such a material include tungsten (W), silver (Ag), copper (Cu), aluminum (Al), and an alloy of Al and copper (Cu). The insulating film 17B is formed using, for example, silicon oxide (SiO) x ) A film, etc.
A multilayer wiring layer 18 is provided on the first surface 11S1 on the opposite side of the light incident surface (second surface 11S 2) of the semiconductor substrate 11. In the multilayer wiring layer 18, wiring layers 181, 182 constituted by one or a plurality of wirings are laminated with an interlayer insulating layer 183 interposed therebetween. The wiring layers 181 and 182 are used, for example, to supply a voltage applied to the semiconductor substrate 11 and the light receiving element 12, or to take out carriers generated in the light receiving element 12. The wiring layer 181 and the wiring layer 182 are electrically connected via the via hole V2, and the wiring of a part of the wiring layer 181 is also electrically connected to the n-type contact electrode 15 and the p-type contact electrode 16 via the via hole V1. A plurality of pad electrodes 184 are buried in a surface (surface 18S1 of the multilayer wiring layer 18) of the interlayer insulating layer 183 on the opposite side to the semiconductor substrate 11 side. The plurality of pad electrodes 184 are electrically connected to a part of the wirings of the wiring layer 182 via the via holes V3. Although fig. 1 shows an example in which two wiring layers 181 and 182 are formed in the multilayer wiring layer 18, the total number of wiring layers in the multilayer wiring layer 18 is not limited to this, and a single layer may be used, or three or more wiring layers may be formed.
The interlayer insulating layer 183 is made of, for example, silicon oxide (SiO) x ) TEOS, silicon nitride (SiN) x ) Silicon oxynitride (SiO) x N y ) Or a single-layer film of one of these, or a laminated film containing two or more of these.
The wiring layers 181 and 182 are formed using aluminum (Al), copper (Cu), tungsten (W), or the like, for example.
The pad electrode 184 is exposed on a bonding surface (surface 18S1 of the multilayer wiring layer 18) with the logic substrate 20, for example, for connection with the logic substrate 20. The pad electrode 184 is formed using copper (Cu), for example.
The logic substrate 20 includes, for example, a semiconductor substrate 21 composed of a silicon substrate and a multilayer wiring layer 22. The logic substrate 20 is provided with the bias voltage applying section 110, for example, an inverter 120, N-type MOSFETs 130 and 140, P-type MOSFET150, a buffer circuit 160, and the like provided for each unit pixel P.
In the multilayer wiring layer 22, the gate wiring 221 of the transistors constituting the inverter 120, the N-type MOSFETs 130, 140, the P-type MOSFET150, and the buffer circuit 160, and the wiring layers 222, 223, 224, 225 of one or more wirings are laminated in order from the semiconductor substrate 21 side with the interlayer insulating layer 226 interposed therebetween. A plurality of pad electrodes 227 are buried in a surface (surface 22S1 of the multilayer wiring layer 22) of the interlayer insulating layer 226 on the opposite side from the semiconductor substrate 21 side. The plurality of pad electrodes 227 are electrically connected to a part of the wirings of the wiring layer 225 via the via holes V4.
The interlayer insulating layer 117 is made of, for example, silicon oxide (SiO x ) TEOS, silicon nitride (SiN) x ) Silicon oxynitride (SiO) x N y ) Or a single-layer film of one of these, or a laminated film containing two or more of these.
The gate wiring 221 and the wiring layers 222, 223, 224, and 225 are formed using aluminum (Al), copper (Cu), tungsten (W), or the like, for example, similarly to the wiring layers 181 and 182.
The pad electrode 227 is exposed on a bonding surface (surface 22S1 of the multilayer wiring layer 22) with the sensor substrate 10, for example, for connection with the sensor substrate 10. The pad electrode 227 is formed using copper (Cu), for example, similarly to the pad electrode 184.
In the photodetector 1, cuCu bonding is performed between the pad electrode 184 and the pad electrode 227, for example. Thus, the cathode of the light receiving element 12 is electrically connected to a power supply of a voltage Vop corresponding to the breakdown voltage of the light receiving element 12 provided on the logic substrate 20 side, and the anode of the light receiving element 12 is electrically connected to the N-type MOSFET130 as a current source provided on the logic substrate 20 side.
On the light incident surface (second surface 11S 2) side of the semiconductor substrate 11, for example, a microlens 31 is provided for each unit pixel P through a passivation film (not shown). Further, a light shielding portion 32 is provided between adjacent microlenses 31.
The microlens 31 condenses light incident from above to the light receiving element 12, and uses silicon oxide (SiO x ) And the like.
The light shielding portion 32 suppresses crosstalk of obliquely incident light between adjacent pixels. The light shielding portion 32 is provided between adjacent unit pixels P in the pixel array portion 100A, for example, and is provided in a lattice shape in the pixel array portion 100A, for example, as in the pixel separation portion 17. The light shielding portion 32 is formed using a conductive material having light shielding properties, similarly to the light shielding film 17A. Specifically, tungsten (W), silver (Ag), copper (Cu), aluminum (Al), an alloy of Al and copper (Cu), or the like is used.
1-2 method for manufacturing light detection device
The light detection device 1 can be manufactured as follows, for example. First, an opening having a predetermined depth is formed on the first surface 11S1 of the semiconductor substrate 11 composed of a silicon substrate corresponding to each unit pixel P. In this case, for example, by using two or more semiconductor substrates such as SOI substrates having different materials as the silicon substrate, the SiO in the layers is formed 2 The layer becomes a barrier and can control the depth of the opening. Next, a semiconductor layer made of, for example, germanium (Ge) or silicon germanium (SiGe) is formed in the opening by an epitaxial crystal growth method such as a metal organic vapor phase epitaxy (Metal Organic Chemical Vapor Deposition (metal organic chemical vapor deposition): MOCVD) method. Next, after the surface of the semiconductor layer is planarized by CMP (Chemical Mechanical Polishing: chemical mechanical polishing), the impurity concentration of the p-type or n-type is controlled on the semiconductor layer by ion implantation, so that n-type semiconductor regions 131 (light receiving portions 13) and 151 (n-type contact electrodes) and p-type semiconductor regions 141 (multiplication portions 14) and 161 (p-type contact electrodes 16) are formed.
Next, on the first surface 11S1 of the semiconductor substrate 11, for example, silicon oxide (SiO x ) Iso-oxide film or (SiN) x ) After patterning the nitride film as a hard mask, a through hole penetrating the semiconductor substrate 11 is formed by etching, for example. Then, the insulating film 17B and the light shielding film 17A are sequentially formed in the through hole by, for example, CVD (Chemical Vapor Deposition: chemical vapor deposition), PVD (Physical Vapor Deposition: physical vapor deposition), ALD (Atomic Layer Deposition: atomic layer deposition), or vapor deposition. Next, for example, by CMP, the light shielding film 17A and the insulating film 17B formed on the first surface 11S1 of the semiconductor substrate 11 using the hard mask as a barrier are removed, and then the multilayer wiring layer 18 is formed on the first surface 11S1 of the semiconductor substrate 11. Then, a separately fabricated logic board 20 is bonded. At this time, the plurality of pad electrodes 184 exposed on the bonding surface (surface 18S 1) of the multilayer wiring layer 18 and the plurality of pad portions 217 exposed on the bonding surface (surface 22S) of the multilayer wiring layer 22 on the logic substrate 20 side are bonded by CuCu. Then, for example, lead toAfter polishing the second surface 11S2 of the semiconductor substrate 11 by CMP, a passivation film, a light shielding portion 32, and a microlens 31 are sequentially formed. Thus, the light detection device 1 shown in fig. 1 is completed.
1-3 action/Effect
In the photodetector 1 of the present embodiment, the light receiving portion 13 formed embedded in the first surface 11S1 side of the semiconductor substrate 11 and the multiplication portion 14 provided on the surface 13S1 of the light receiving portion 13 forming substantially the same surface as the first surface 11S1 of the semiconductor substrate 11 are formed using semiconductors (for example, germanium (Ge) or compound semiconductors of silicon (Si) and germanium (Ge)) having a narrower band gap than the semiconductor substrate 11, respectively, so that lattice mismatch at the interface between the light receiving portion 13 and the multiplication portion 14 is alleviated. This will be explained below.
In recent years, a distance image sensor that performs distance measurement by the ToF method has received attention as a light detection device. The range image sensor includes a pixel array section in which a plurality of pixels are arranged in a matrix, and the efficiency of the entire device is determined by the size and pixel structure of the pixels.
However, as a method of increasing the height with respect to the near infrared rays in the photodetection device having the avalanche photodiode element for each unit pixel P, it is conceivable to thicken the thickness of the semiconductor layer forming the avalanche region. However, if the semiconductor layer is thickened, there is a possibility that timing jitter characteristics deteriorate.
As another method for increasing the height relative to the near infrared ray in the above-described light detection device, it is conceivable to form the light receiving portion using a semiconductor having a narrow band gap. For example, a light receiving portion is formed using germanium (Ge) as a low band gap semiconductor, and an avalanche multiplication region is formed at a junction with a silicon substrate. However, in the case where the heterojunction portion forms an avalanche multiplication region, there is a possibility that dark current increases at the junction interface due to lattice mismatch.
In contrast, in the present embodiment, the light receiving portion 13 and the multiplication portion 14 buried in the first surface 11S1 side of the semiconductor substrate 11 are formed using a semiconductor having a narrower band gap than the semiconductor substrate 11 (for example, germanium (Ge) or a compound semiconductor of silicon (Si) and germanium (Ge)). Thereby, lattice mismatch at the interface of the light receiving portion 13 and the multiplying portion 14 is relaxed.
Thus, in the photodetector 1 of the present embodiment, the light receiving portion 13 and the multiplication portion 14 are formed using, for example, germanium (Ge) or a compound semiconductor of silicon (Si) and germanium (Ge) having a narrower band gap than the semiconductor substrate 11, and therefore, the occurrence of dark current at the interface between the light receiving portion 13 and the multiplication portion 14 can be reduced.
In the photodetector 1 of the present embodiment, the light receiving element 12 including the light receiving portion 13 and the multiplication portion 14 is formed using germanium (Ge), silicon (Si), and a compound semiconductor of germanium (Ge) (for example, silicon germanium (SiGe)) which are low band gap semiconductors, and therefore, the thickness of the light receiving portion 13 can be reduced in accordance with an improvement in sensitivity to near infrared rays as compared with the case where silicon (Si) is used. Therefore, timing jitter characteristics can be improved.
Next, modifications 1 to 10, and application examples of the present disclosure will be described. The same reference numerals are given to the same constituent elements as those of the above embodiment, and the description thereof will be omitted as appropriate.
2. Modification examples
2-1 modification 1
Fig. 6 schematically shows an example of a cross-sectional configuration of a light detection device (light detection device 1A) according to modification 1 of the present disclosure. The light detection device 1A is applied to, for example, a distance image sensor (distance image device 1000) that performs distance measurement by the ToF method, an image sensor, and the like, as in the above-described embodiments. The photodetection device 1A of the present modification differs from the above embodiment in that an n-type semiconductor region (n + ) 132. The n-type semiconductor region 132 corresponds to one specific example of the "third semiconductor region" of the present disclosure.
In the light detection device 1A, as described above, the n-type semiconductor region 132 having an impurity concentration higher than that of the n-type semiconductor region 131 is provided near the semiconductor substrate 11 of the light receiving portion 13, specifically, at the peripheral edge portion of the light receiving portion 13. In the present modification, an n-type contact electrode 15 connected to the cathode is formed in the n-type semiconductor region 132.
As a result, a cathode potential can be selectively applied to the vicinity of the semiconductor substrate 11, that is, to the side surface portion of the light receiving section 13 and the bottom surface portion on the opposite side of the multiplication section 14, and a potential gradient can be formed between the peripheral edge portion of the light receiving section 13 and the multiplication section 14, and the multiplication section 14 is formed at the substantially center in a plan view of the surface 13S1 of the light receiving section 13. Therefore, carriers (electrons) generated in the light receiving portion 13 by photoelectric conversion can be efficiently transferred to the multiplication portion 14. Therefore, in addition to the effects of the above-described embodiments, the timing jitter characteristics can be further improved.
In the present modification, as shown in fig. 6, an example is shown in which an n-type semiconductor region 132 having a higher impurity concentration than the n-type semiconductor region 131 and a uniform impurity concentration is provided in the vicinity of the semiconductor substrate 11 of the light receiving portion 13, but an n-type semiconductor region having a different impurity concentration or a different impurity type may be formed in the vicinity of the semiconductor substrate 11 of the light receiving portion 13.
Specifically, as shown in fig. 7, for example, an n-type semiconductor region (n + ) 132, an n-type semiconductor region (n ++ ) 133. In this way, by further providing the n-type semiconductor region 133 having a high impurity concentration on the bottom surface portion of the light receiving portion 13, carriers (electrons) generated in the light receiving portion 13 by photoelectric conversion can be more efficiently transferred to the multiplication portion 14.
Further, in the n-type semiconductor region 131 surrounded by the n-type semiconductor region 132 or the n-type semiconductor region 132 and the n-type semiconductor region 133, for example, as shown in fig. 8, an impurity concentration gradient in which the impurity concentration continuously or stepwise decreases from the second surface 11S2 side toward the first surface 11S1 of the semiconductor substrate 11 may be formed. This allows carriers generated in the light receiving unit 13 by photoelectric conversion to be efficiently transferred to the multiplication unit 14.
2-2 modification 2
Fig. 9 schematically shows an example of a cross-sectional configuration of a light detection device (light detection device 1B) according to modification 2 of the present disclosure. The light detection device 1B is applied to, for example, a distance image sensor (distance image device 1000) that performs distance measurement by the ToF method, an image sensor, and the like, as in the above-described embodiment. The photodetection device 1B of the present modification differs from the above embodiment in that a p-type semiconductor region (p) 142 having a lower impurity concentration than the p-type semiconductor region 141 is provided around the p-type semiconductor region 141 constituting the multiplication section 14 in a plan view. The p-type semiconductor region 142 corresponds to one specific example of the "fourth semiconductor region" of the present disclosure.
The p-type semiconductor region 142 functions as a guard ring. By providing the p-type semiconductor region 142 around the p-type semiconductor region 141 constituting the multiplier section 14, the fringe electric field is relaxed. Further, the avalanche multiplication region 12X is selectively formed in the p-type semiconductor region 141 inside the p-type semiconductor region 142.
As described above, in the present modification, since the guard ring structure is provided along the side surface of the multiplication unit 14, unexpected breakdown can be reduced in addition to the effects of the above embodiment.
2-3 modification 3
Fig. 10 schematically shows an example of a cross-sectional configuration of a light detection device (light detection device 1C) according to modification 3 of the present disclosure. The light detection device 1C is applied to, for example, a distance image sensor (distance image device 1000) that performs distance measurement by the ToF method, an image sensor, and the like, as in the above-described embodiment. The photodetection device 1C according to the present modification differs from the above embodiment in that the n-type contact electrode 15 and the p-type contact electrode 16 are provided on the light receiving section 13 and the multiplying section 14, respectively.
The n-type contact electrode 15 and the p-type contact electrode 16 according to this modification are formed as, for example, epitaxial layers formed by epitaxial crystal growth, on the semiconductor layers constituting the light receiving section 13 and the multiplication section 14.
Thus, in the present modification, the n-type contact electrode 15 and the p-type contact electrode 16, which are made of, for example, epitaxial layers, are provided on the light receiving section 13 and the multiplication section 14, respectively. As a result, as in the above embodiment, the edge withstand voltage is improved as compared with the case where the n-type contact electrode 15 and the p-type contact electrode 16 are provided in the surface 13S1 of the light receiving portion 13 and the surface 14S of the multiplication portion 14, in other words, in the semiconductor layers constituting the light receiving portion 13 and the multiplication portion 14. Accordingly, in addition to the effects of the above embodiments, unintended breakdown can be reduced.
2-4 modification 4
Fig. 11 schematically shows an example of a cross-sectional configuration of a light detection device (light detection device 1D) according to modification 4 of the present disclosure. The light detection device 1D is applied to, for example, a distance image sensor (distance image device 1000) that performs distance measurement by the ToF method, an image sensor, and the like, as in the above-described embodiment. The photodetection device 1D of the present modification differs from the above embodiment in that the light receiving unit 13 is provided with a multiplication unit 14.
The multiplier section 14 according to the present modification is formed as an epitaxial layer formed by epitaxial crystal growth, for example, on the surface 13S1 of the light receiving section 13, that is, on a semiconductor layer constituting the light receiving section 13.
Thus, in the present modification, the multiplier section 14 is provided on the light receiving section 13. As a result, the distance between the n-type contact electrode 15 provided in the light receiving section 13 and the p-type contact electrode 16 provided in the multiplication section 14 is greater than in the case where the multiplication section 14 is provided near the surface 13S1 in the light receiving section 13 as in the above-described embodiment, and therefore, the fringe electric field is relaxed. Accordingly, in addition to the effects of the above embodiments, unintended breakdown can be reduced.
2-5 modification 5
Fig. 12 schematically shows an example of a cross-sectional configuration of a light detection device (light detection device 1E) according to modification 5 of the present disclosure. The light detection device 1E is applied to, for example, a distance image sensor (distance image device 1000) that performs distance measurement by the ToF method, an image sensor, and the like, as in the above-described embodiment. The side surface 14S3 of the multiplier 14 may be an inclined surface. Specifically, in the multiplier section 14, the side surface 14S3 may be inclined so that the angle formed by the surface 14S1 and the side surface 14S3 is an acute angle.
2-6 modification 6
Fig. 13 schematically shows an example of a cross-sectional configuration of a light detection device (light detection device 1F) according to modification 6 of the present disclosure. The light detection device 1F is applied to, for example, a distance image sensor (distance image device 1000) that performs distance measurement by the ToF method, an image sensor, and the like, as in the above-described embodiment. The size of the avalanche multiplication region 12X formed at the junction of the n-type semiconductor region 131 and the p-type semiconductor region 141 is not limited, and the n-type semiconductor region 131 constitutes the multiplication section 14 and the light receiving section 13, and the p-type semiconductor region 141 constitutes the multiplication section 14.
In the above embodiment, the light receiving portion 13 and the multiplication portion 14 are formed using germanium (Ge), silicon (Si), and a compound semiconductor of germanium (Ge) (for example, silicon germanium (SiGe)) which are low band gap semiconductors. Therefore, as in the photodetector 1F of the present modification, the tunneling current can be reduced by reducing the volume of the multiplication section 14 having a high electric field.
Further, as shown in fig. 14, in the case where the multiplication section 14 is provided on the surface 13S1 of the light receiving section 13 in combination with the modification 4 described above, unintended breakdown can be reduced.
2-7 modification 7
Fig. 15 schematically shows an example of a cross-sectional configuration of a light detection device (light detection device 1G) according to modification 7 of the present disclosure. The light detection device 1G is applied to, for example, a distance image sensor (distance image device 1000) that performs distance measurement by the ToF method, an image sensor, and the like, as in the above-described embodiment. The photodetection device 1G according to the present modification differs from the above embodiment in that a buffer layer 19 is provided between the semiconductor substrate 11 and the light receiving section 13.
The buffer layer 19 serves to alleviate lattice mismatch at the interface between the semiconductor substrate 11 and the light receiving portion 13. The buffer layer 19 is formed of, for example, a semiconductor having a lattice constant between that of a silicon substrate constituting the semiconductor substrate 11 and that of a germanium (Ge), silicon (Si), and a compound semiconductor of germanium (Ge) (for example, silicon germanium (SiGe)) constituting the light receiving portion 13. Specifically, for example, the buffer layer 19 is formed of a silicon germanium (SiGe) layer in which the concentration ratio of silicon (Si) to germanium (Ge) is changed from one to a plurality. This can alleviate lattice mismatch between silicon (Si) and germanium (Ge). The buffer layer 19 can be formed by, for example, epitaxial crystal growth.
Thus, in the present modification, the buffer layer 19 made of a semiconductor having a lattice constant between the lattice constants of the semiconductor substrate 11 and the light receiving portion 13 is provided between the semiconductor substrate 11 and the light receiving portion 13, and therefore, the occurrence of dark current at the interface between the semiconductor substrate 11 and the light receiving portion 13 can be reduced.
2-8 modification 8
Fig. 16 schematically shows an example of a cross-sectional configuration of a light detection device (light detection device 1H) according to modification 8 of the present disclosure. The light detection device 1H is applied to, for example, a distance image sensor (distance image device 1000) that performs distance measurement by the ToF method, an image sensor, and the like, as in the above-described embodiment. The photodetection device 1H according to the present modification differs from the above embodiment in that part of the wiring (for example, the wiring 181A) of the plurality of wiring layers 181 and 182 provided in the interlayer insulating layer 183 is formed to extend in the XY plane direction so as to face the light receiving element 12. The wiring 181A corresponds to one specific example of the "light reflection portion" of the present disclosure.
Thus, in the present modification, the light reflection portion is provided at a position facing the light receiving element 12 by a part of the wiring (for example, the wiring 181A) of the plurality of wiring layers 181 and 182 constituting the multilayer wiring layer 18. Thus, light that has not been absorbed by the light receiving portion 13 and transmitted through the multilayer wiring layer 18 is reflected by the wiring 181A and enters the light receiving portion 13 again. Therefore, in addition to the effects of the above embodiments, the sensitivity can be further improved.
2-9 modification 9
Fig. 17 schematically shows an example of a cross-sectional configuration of a light detection device (light detection device 1I) according to modification 9 of the present disclosure. The light detection device 1I is applied to, for example, a distance image sensor (distance image device 1000) that performs distance measurement by the ToF method, an image sensor, and the like, as in the above-described embodiment. The photodetection device 1I of the present modification differs from the above embodiment in that the second surface 11S2 of the semiconductor substrate 11 is provided with a concave-convex structure.
Thus, in the present modification, since the concave-convex structure is provided on the second surface 11S2 of the semiconductor substrate 11 as the light incident surface, the light incident on the light receiving portion 13 is diffusely reflected, and the amount of light incident on the light receiving portion 13 is homogenized on the two-dimensional plane. Therefore, in addition to the effects of the above embodiments, the sensitivity can be further improved.
2-10 modification 10
Fig. 18 schematically shows an example of a cross-sectional configuration of a light detection device (light detection device 1J) according to modification 10 of the present disclosure. The light detection device 1J is applied to, for example, a distance image sensor (distance image device 1000) that performs distance measurement by the ToF method, an image sensor, and the like, as in the above-described embodiment. The photodetection device 1J of the present modification differs from the above-described embodiment in that the semiconductor substrate 11 is used as a support substrate (growth substrate), and the semiconductor layer 41 made of germanium (Ge), silicon (Si), and a compound semiconductor of germanium (Ge) (for example, silicon germanium (SiGe)) is formed on the entire surface of the first surface 11S1 of the semiconductor substrate 11 by, for example, epitaxial crystal growth, and the P-well 411 is provided between adjacent unit pixels P instead of the pixel separation portion 17 in the above-described embodiment.
Thus, in the present modification, the semiconductor layer 41 made of germanium (Ge) or silicon germanium (SiGe) is formed on the entire surface of the first surface 11S1 of the semiconductor substrate 11, for example, and the P-well 411 is provided between adjacent unit pixels P as a separation section for electrically separating the adjacent unit pixels P. As a result, the area of the light receiving portion 13 can be enlarged as compared with the case where the pixel separation portion 17 including the light shielding film 17A and the insulating film 17B is provided as in the above-described embodiment. Therefore, in addition to the effects of the above embodiments, the sensitivity can be improved.
As shown in fig. 19, the pixel separation portion 17 provided between adjacent unit pixels P of the semiconductor substrate 11 may be omitted. This can enlarge the area of the light receiving section 13, and can improve sensitivity.
3. Application example
Fig. 20 shows an example of a schematic configuration of a range image device 1000 as an electronic device including the light detection devices (for example, the light detection device 1) according to the above-described embodiments and modifications 1 to 10. The distance image device 1000 corresponds to one specific example of the "distance measuring device" of the present disclosure.
The distance image apparatus 1000 includes, for example, a light source apparatus 1100, an optical system 1200, a light detection apparatus 1, an image processing circuit 1300, a monitor 1400, and a memory 1500.
The distance image apparatus 1000 can acquire a distance image corresponding to the distance to the irradiation target object 2000 by receiving light (modulated light, pulsed light) projected from the light source apparatus 1100 toward the irradiation target object 2000 and reflected by the surface of the irradiation target object 2000.
The optical system 1200 is configured to have one or more lenses, and to guide image light (incident light) from the irradiation target object 2000 to the light detection device 1 and to image the image light on the light receiving surface (sensor portion) of the light detection device 1.
The image processing circuit 1300 performs image processing for constructing a distance image based on the distance signal supplied from the light detection device 1, and the distance image (image data) obtained by the image processing is supplied to the monitor 1400 and displayed or supplied to the memory 1500 and stored (recorded).
In the distance image apparatus 1000 configured as described above, by using the above-described light detection device (for example, the light detection device 1), it is possible to generate a high-precision distance image by calculating the distance to the irradiation target object 2000 based only on the light receiving signal from the unit pixel P having high stability. That is, the range image device 1000 can acquire a more accurate range image.
4. Application example
Application example to moving object
The technology related to the present disclosure can be applied to various products. For example, the technology according to the present disclosure may be implemented as a device mounted on any one of moving bodies such as an automobile, an electric automobile, a hybrid electric automobile, a motorcycle, a bicycle, a personal mobile device, an airplane, an unmanned aerial vehicle, a ship, a robot, a construction machine, and an agricultural machine (tractor).
Fig. 21 is a block diagram showing a schematic configuration example of a vehicle control system as an example of a mobile body control system to which the technology according to the present disclosure can be applied.
The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in fig. 21, the vehicle control system 12000 includes a drive system control unit 12010, a main body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and a comprehensive control unit 12050. Further, as the functional configuration of the integrated control unit 12050, a microcomputer 12051, an audio/video output unit 12052, and an in-vehicle network I/F (interface) 12053 are shown.
The drive system control unit 12010 controls the operations of devices related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 functions as a control device such as a drive force generating device for generating a drive force of a vehicle such as an internal combustion engine or a drive motor, a drive force transmitting mechanism for transmitting the drive force to wheels, a steering mechanism for adjusting a steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.
The main body system control unit 12020 controls operations of various devices mounted to the vehicle body according to various programs. For example, the main body system control unit 12020 functions as a control device for various lamps such as a keyless entry system, a smart key system, a power window device, a headlight, a backlight, a brake lamp, a turn signal lamp, and a fog lamp. In this case, radio waves transmitted from a portable device instead of a key or signals of various switches may be input to the main body system control unit 12020. The main body system control unit 12020 receives these inputs of electric waves and signals, and controls a door lock device, a power window device, a lamp, and the like of the vehicle.
The vehicle exterior information detection unit 12030 detects information on the outside of the vehicle on which the vehicle control system 12000 is mounted. For example, the outside-vehicle information detection unit 12030 is connected to the image pickup unit 12031. The vehicle exterior information detection unit 12030 causes the imaging unit 12031 to capture an image of the exterior of the vehicle, and receives the captured image. The outside-vehicle information detection unit 12030 may also perform object detection processing or distance detection processing of persons, vehicles, obstacles, marks, characters on a road surface, or the like, based on the received image.
The image pickup unit 12031 is a photosensor that receives light and outputs an electrical signal corresponding to the amount of the received light. The image pickup unit 12031 may output an electric signal as an image, or may output an electric signal as distance measurement information. The light received by the image pickup unit 12031 may be visible light or non-visible light such as infrared light.
The in-vehicle information detection unit 12040 detects in-vehicle information. The in-vehicle information detection unit 12040 is connected to, for example, a driver state detection unit 12041 that detects the state of the driver. The driver state detection unit 12041 includes, for example, a camera that photographs the driver, and the in-vehicle information detection unit 12040 may calculate the fatigue degree or concentration degree of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing.
The microcomputer 12051 can calculate a control target value of the driving force generating device, steering mechanism, or braking device based on the information on the inside and outside of the vehicle acquired by the outside-vehicle information detecting unit 12030 or the inside-vehicle information detecting unit 12040, and output a control instruction to the drive system control unit 12010. For example, the microcomputer 12051 can perform coordinated control for the purpose of realizing the functions of an ADAS (Advanced Driver Assistance System: advanced driver assistance system) including collision avoidance or impact alleviation of a vehicle, following travel based on an inter-vehicle distance, vehicle speed maintenance travel, collision warning of a vehicle, lane departure warning of a vehicle, and the like.
The microcomputer 12051 controls the driving force generating device, the steering mechanism, the braking device, or the like based on the information on the surroundings of the vehicle acquired by the outside-vehicle information detecting unit 12030 or the inside-vehicle information detecting unit 12040, so that it is possible to perform coordinated control for automatic driving that autonomously runs independently of the operation of the driver.
Further, the microcomputer 12051 can output a control instruction to the main body system control unit 12020 based on the information outside the vehicle acquired by the outside-vehicle information detection unit 12030. For example, the microcomputer 12051 can control the head lamp based on the position of the front vehicle or the opposite vehicle detected by the outside information detecting unit 12030, and perform coordinated control for the purpose of realizing antiglare, such as switching the high beam to the low beam.
The audio/video output unit 12052 transmits an output signal of at least one of audio and video to an output device that can visually or audibly notify information to a passenger of the vehicle or the outside of the vehicle. In the example of fig. 21, an audio speaker 12061, a display unit 12062, and a dashboard 12063 are shown as examples of the output device. The display unit 12062 may include at least one of an in-vehicle display and a head-up display, for example.
Fig. 22 is a diagram showing an example of the installation position of the image pickup unit 12031.
In fig. 22, imaging units 12101, 12102, 12103, 12104, and 12105 are provided as imaging units 12031.
The imaging units 12101, 12102, 12103, 12104, 12105 are provided at positions such as the front nose, side view mirror, rear bumper, rear door, and upper part of a front windshield in the vehicle cabin of the vehicle 12100. An imaging unit 12101 provided in the nose and an imaging unit 12105 provided in the upper portion of the front windshield in the vehicle interior mainly acquire an image of the front of the vehicle 12100. The imaging units 12102 and 12103 provided in the side view mirror mainly acquire images of the sides of the vehicle 12100. The image pickup unit 12104 provided in the rear bumper or the rear door mainly acquires an image of the rear of the vehicle 12100. The image pickup unit 12105 provided at the upper portion of the front windshield in the vehicle compartment is mainly used for detecting a preceding vehicle or a pedestrian, an obstacle, a traffic signal, a traffic sign, or a lane.
Fig. 22 shows an example of the imaging ranges of the imaging units 12101 to 12104. The imaging range 12111 indicates the imaging range of the imaging unit 12101 provided at the front nose, the imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided at the side view mirror, and the imaging range 12114 indicates the imaging range of the imaging unit 12104 provided at the rear bumper or the rear door. For example, by superimposing the image data captured by the image capturing sections 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.
At least one of the image pickup units 12101 to 12104 may also have a function of acquiring distance information. For example, at least one of the image pickup units 12101 to 12104 may be a stereo camera including a plurality of image pickup elements, or may be an image pickup element having pixels for detecting a phase difference.
For example, the microcomputer 12051 obtains the distance to each solid object in the imaging ranges 12111 to 12114 and the time variation of the distance (relative speed to the vehicle 12100) based on the distance information obtained from the imaging units 12101 to 12104, and can extract, as a vehicle ahead, a nearest solid object that is particularly located on the travel path of the vehicle 12100 and that travels at a predetermined speed (for example, 0km/h or more) in approximately the same direction as the vehicle 12100. The microcomputer 12051 can set a vehicle distance to be secured immediately before the preceding vehicle in advance, and perform automatic braking control (including follow-up stop control) and automatic acceleration control (including follow-up start control). In this way, coordination control for the purpose of automatic driving or the like that autonomously travels without depending on the operation of the driver can be performed.
For example, the microcomputer 12051 can classify and extract the related stereo data of the stereo based on the distance information obtained from the image pickup sections 12101 to 12104 as another stereo such as a two-wheeled vehicle, a general vehicle, a large vehicle, a pedestrian, a utility pole, and the like, and is used for automatically avoiding an obstacle. For example, the microcomputer 12051 recognizes the obstacle around the vehicle 12100 as an obstacle that the driver of the vehicle 12100 can visually confirm and an obstacle that is difficult to visually confirm. The microcomputer 12051 determines a collision risk indicating a risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and there is a possibility of collision, outputs an alarm to the driver through the audio speaker 12061 and the display unit 12062, and performs forced deceleration and steering avoidance through the drive system control unit 12010, thereby enabling driving assistance for avoiding collision.
At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can identify a pedestrian by determining whether or not there is a pedestrian in the captured images of the image capturing sections 12101 to 12104. The recognition of the pedestrian is performed, for example, by a step of extracting feature points in the captured images of the imaging sections 12101 to 12104 as infrared cameras, and a step of discriminating whether or not the pedestrian is a pedestrian by performing pattern matching processing on a series of feature points representing the outline of the object. When the microcomputer 12051 determines that there is a pedestrian in the captured images of the image capturing sections 12101 to 12104 and recognizes the pedestrian, the sound image output section 12052 controls the display section 12062 so that the square outline for emphasis is superimposed on the recognized pedestrian. The audio/video output unit 12052 may control the display unit 12062 to display an icon or the like indicating a pedestrian at a desired position.
While the embodiments and modifications 1 to 10 and the application examples and application examples have been described above, the present disclosure is not limited to the above embodiments and the like, and various modifications are possible. For example, in the above embodiment and the like, an example in which holes are used as signal charges has been shown, but electrons may be used as signal charges.
In the above embodiment and the like, an example in which a negative potential is applied to the cathode has been shown, but the respective potentials are not limited as long as they are in a state in which avalanche multiplication is caused by applying a reverse bias between the anode and the cathode.
The effects described in the above embodiments and the like are examples, and other effects may be included.
The present disclosure may be configured as described below. According to the present technique of the following configuration, a light receiving portion and a multiplication portion are formed using semiconductors having narrower band gaps than the semiconductor substrate, respectively, the light receiving portion being buried in a first surface side of the semiconductor substrate having a first surface and a second surface which are opposed to each other, and the multiplication portion being provided in the vicinity of a surface of the light receiving portion which forms substantially the same surface as the first surface of the semiconductor substrate. Thus, lattice mismatch at the interface between the light receiving portion and the multiplication portion is relaxed, and generation of dark current can be reduced.
(1) A light detection device is provided with: a semiconductor substrate having a first surface and a second surface which face each other, and having a pixel array portion in which a plurality of pixels are arranged in an array; a light receiving portion buried in the first surface side of the semiconductor substrate for each pixel, the light receiving portion being formed of a semiconductor having a narrower band gap than the semiconductor substrate, and generating carriers corresponding to a light receiving amount by photoelectric conversion; and a multiplication unit provided near a surface of the light receiving unit on which substantially the same surface as the first surface of the semiconductor substrate is formed, the multiplication unit being configured to perform avalanche multiplication on carriers generated in the light receiving unit, and the multiplication unit being configured by the semiconductor having a narrower band gap than the semiconductor substrate.
(2) The light detection device according to the above (1), wherein the multiplication section is provided inside or on the light receiving section.
(3) The light detection device according to the item (1) or (2), wherein the light receiving portion is formed of a first semiconductor region having a first conductivity type, the multiplication portion is formed of a second semiconductor region having a second conductivity type, and an avalanche multiplication region is formed at an interface of the first semiconductor region and the second semiconductor region.
(4) The photodetecting device according to the item (3), wherein the light receiving portion further has a third semiconductor region of the first conductivity type having an impurity concentration higher than that of the first semiconductor region in the vicinity of the semiconductor substrate.
(5) The light detection device according to the (4), wherein in the third semiconductor region, there is a different impurity concentration or impurity species at a side face portion of the light receiving portion and a bottom portion of the second face facing the semiconductor substrate.
(6) The photodetecting device according to any one of (1) to (5), wherein the light receiving portion has an impurity concentration gradient in which an impurity concentration continuously or stepwise decreases from the second surface side toward the first surface side of the semiconductor substrate.
(7) The light detection device according to any one of (3) to (6), further comprising: and a guard ring provided along a side surface of the multiplication unit formed inside the light receiving unit, and adapted to mitigate a fringe electric field of the multiplication unit.
(8) The photodetection device according to the item (7), wherein the guard ring has the same conductivity type as the second semiconductor region forming the multiplication section, and the guard ring is formed of a fourth semiconductor region having an impurity concentration lower than that of the second semiconductor region.
(9) The light detection device according to any one of (3) to (8), further comprising: the first electrode is electrically connected to the light receiving portion through a first contact electrode having the first conductivity type provided in the vicinity of the surface of the light receiving portion, and the second electrode is electrically connected to the multiplication portion through a second contact electrode having the second conductivity type provided in the vicinity of the surface of the multiplication portion.
(10) The light detection device according to the item (9), wherein the first contact electrode is provided inside or on the light receiving portion, and the second contact electrode is provided inside or on the multiplication portion.
(11) The photodetection device according to the item (9) or (10), wherein the first contact electrode is continuously or intermittently provided around the multiplication section in a plan view.
(12) The light detection device according to any one of (1) to (11), wherein the multiplication section has a polygonal shape or a circular shape in a plan view.
(13) The light detection device according to any one of (1) to (12), wherein a side surface of the multiplication section is inclined.
(14) The light detection device according to any one of (1) to (13), wherein a buffer layer formed of a semiconductor having a lattice constant between a lattice constant of a semiconductor constituting the semiconductor substrate and a lattice constant of a semiconductor constituting the light receiving portion is further provided between the semiconductor substrate and the light receiving portion.
(15) The light detection device according to any one of (1) to (4), wherein the semiconductor substrate further has a separation portion that divides the plurality of pixels, respectively.
(16) The photodetecting device according to (15), wherein the separation portion is formed of a conductive film having light shielding properties and an insulating film provided between the conductive film and the semiconductor substrate.
(17) The light detection device according to the item (15), wherein the separation portion is formed of a semiconductor region of a different conductivity type from the light receiving portion.
(18) The light detection device according to any one of (1) to (17), wherein the semiconductor is germanium or silicon germanium.
(19) The light detection device according to any one of (1) to (18), wherein the semiconductor substrate is a silicon substrate.
(20) A distance measuring device is provided with: an optical system, a light detection device, and a signal processing circuit for calculating a distance to a measurement object from an output signal of the light detection device, wherein the light detection device comprises: a semiconductor substrate having a first surface and a second surface which face each other, and having a pixel array portion in which a plurality of pixels are arranged in an array; a light receiving portion buried in the first surface side of the semiconductor substrate for each pixel, the light receiving portion being formed of a semiconductor having a narrower band gap than the semiconductor substrate, and generating carriers corresponding to a light receiving amount by photoelectric conversion; and a multiplication unit provided near a surface of the light receiving unit on which substantially the same surface as the first surface of the semiconductor substrate is formed, the multiplication unit being configured to perform avalanche multiplication on carriers generated in the light receiving unit, and the multiplication unit being configured by the semiconductor having a narrower band gap than the semiconductor substrate.
The present application claims priority based on japanese patent application No. 2020-202216 filed in the japanese franchise on month 4 of 2020, the entire contents of which are incorporated herein by reference.
It should be understood that various modifications, combinations, sub-combinations, and alterations may occur to those skilled in the art based on design considerations and other factors, but are included within the scope of the appended claims and equivalents thereof.

Claims (20)

1. A light detection device is provided with:
a semiconductor substrate having a first surface and a second surface which face each other, and having a pixel array portion in which a plurality of pixels are arranged in an array;
a light receiving portion buried in the first surface side of the semiconductor substrate for each pixel, the light receiving portion being formed of a semiconductor having a narrower band gap than the semiconductor substrate, and generating carriers corresponding to a light receiving amount by photoelectric conversion; and
and a multiplication unit provided near a surface of the light receiving unit, the surface being substantially the same as the first surface of the semiconductor substrate, the multiplication unit being configured to avalanche multiply carriers generated in the light receiving unit, and the multiplication unit being configured by the semiconductor having a narrower band gap than the semiconductor substrate.
2. The light detecting device as in claim 1, wherein,
the multiplication unit is provided in the light receiving unit or on the light receiving unit.
3. The light detecting device as in claim 1, wherein,
the light receiving portion is formed of a first semiconductor region having a first conductivity type,
the multiplication section is formed by a second semiconductor region having a second conductivity type,
an avalanche multiplication region is formed at an interface of the first semiconductor region and the second semiconductor region.
4. The light detecting device as in claim 3, wherein,
in the light receiving portion, a third semiconductor region of the first conductivity type having an impurity concentration higher than that of the first semiconductor region is further provided in the vicinity of the semiconductor substrate.
5. The light detecting device as in claim 4, wherein,
in the third semiconductor region, there is a different impurity concentration or impurity species at a side face portion of the light receiving portion and a bottom portion of the second face facing the semiconductor substrate.
6. The light detecting device as in claim 1, wherein,
the light receiving portion has an impurity concentration gradient in which an impurity concentration continuously or stepwise decreases from the second surface side toward the first surface side of the semiconductor substrate.
7. The light detection device according to claim 3, further comprising:
and a guard ring provided along a side surface of the multiplication unit formed inside the light receiving unit, and adapted to mitigate a fringe electric field of the multiplication unit.
8. The light detecting device of claim 7, wherein,
the guard ring has the same conductivity type as the second semiconductor region forming the multiplication section, and is formed of a fourth semiconductor region having an impurity concentration lower than that of the second semiconductor region.
9. The light detection device according to claim 3, further comprising:
a first electrode electrically connected to the light receiving section, and a second electrode electrically connected to the multiplication section,
the first electrode is electrically connected to the light receiving portion through a first contact electrode having the first conductivity type provided near a surface of the light receiving portion,
the second electrode is electrically connected to the multiplication section through a second contact electrode having the second conductivity type provided near the surface of the multiplication section.
10. The light detecting device of claim 9, wherein,
the first contact electrode is arranged in the light receiving part or on the light receiving part,
The second contact electrode is provided inside or on the multiplication section.
11. The light detecting device of claim 9, wherein,
in a plan view, the first contact electrode is continuously or intermittently provided around the multiplication section.
12. The light detecting device as in claim 1, wherein,
in a plan view, the multiplication section has a polygonal shape or a circular shape.
13. The light detecting device as in claim 1, wherein,
the sides of the multiplication section are inclined.
14. The light detecting device as in claim 1, wherein,
a buffer layer formed of a semiconductor having a lattice constant between a lattice constant of the semiconductor constituting the semiconductor substrate and a lattice constant of the semiconductor constituting the light receiving portion is further provided between the semiconductor substrate and the light receiving portion.
15. The light detecting device as in claim 1, wherein,
the semiconductor substrate further has a separation section that divides the plurality of pixels, respectively.
16. The light detecting device of claim 15, wherein,
the separation portion is formed of a conductive film having light shielding properties and an insulating film provided between the conductive film and the semiconductor substrate.
17. The light detecting device of claim 15, wherein,
the separation portion is formed of a semiconductor region of a different conductivity type from the light receiving portion.
18. The light detecting device as in claim 1, wherein,
the semiconductor is germanium or silicon germanium.
19. The light detecting device as in claim 1, wherein,
the semiconductor substrate is a silicon substrate.
20. A distance measuring device is provided with:
an optical system, a light detection device, and a signal processing circuit for calculating a distance to a measurement object based on an output signal of the light detection device,
the light detection device is provided with:
a semiconductor substrate having a first surface and a second surface which face each other, and having a pixel array portion in which a plurality of pixels are arranged in an array;
a light receiving portion buried in the first surface side of the semiconductor substrate for each pixel, the light receiving portion being formed of a semiconductor having a narrower band gap than the semiconductor substrate, and generating carriers corresponding to a light receiving amount by photoelectric conversion; and
and a multiplication unit provided near a surface of the light receiving unit, the surface being substantially the same as the first surface of the semiconductor substrate, the multiplication unit being configured to avalanche multiply carriers generated in the light receiving unit, and the multiplication unit being configured by the semiconductor having a narrower band gap than the semiconductor substrate.
CN202180080131.3A 2020-12-04 2021-11-12 Light detection device and distance measuring device Pending CN116568991A (en)

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JP2020-202216 2020-12-04
JP2020202216A JP2022089651A (en) 2020-12-04 2020-12-04 Light detection device and distance measurement device
PCT/JP2021/041707 WO2022118635A1 (en) 2020-12-04 2021-11-12 Light detection device and distance measurement device

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US7759650B2 (en) * 2006-04-25 2010-07-20 Koninklijke Philips Electronics N.V. Implementation of avalanche photo diodes in (Bi)CMOS processes
DE112016005522T5 (en) * 2015-12-03 2018-08-30 Sony Semiconductor Solutions Corporation Semiconductor imaging element and imaging device
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JP7058479B2 (en) * 2016-10-18 2022-04-22 ソニーセミコンダクタソリューションズ株式会社 Photodetector
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