WO2020127304A1 - Structure de pixels destinée à la mesure de distance optique sur un objet et système de détection de la distance associé - Google Patents

Structure de pixels destinée à la mesure de distance optique sur un objet et système de détection de la distance associé Download PDF

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Publication number
WO2020127304A1
WO2020127304A1 PCT/EP2019/085700 EP2019085700W WO2020127304A1 WO 2020127304 A1 WO2020127304 A1 WO 2020127304A1 EP 2019085700 W EP2019085700 W EP 2019085700W WO 2020127304 A1 WO2020127304 A1 WO 2020127304A1
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WIPO (PCT)
Prior art keywords
pixel
sub
photoactive
storage node
gate
Prior art date
Application number
PCT/EP2019/085700
Other languages
German (de)
English (en)
Inventor
Nadine Sticherling
Oliver MÜLLER
Original Assignee
Huf Hülsbeck & Fürst Gmbh & Co. Kg
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Application filed by Huf Hülsbeck & Fürst Gmbh & Co. Kg filed Critical Huf Hülsbeck & Fürst Gmbh & Co. Kg
Publication of WO2020127304A1 publication Critical patent/WO2020127304A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/483—Details of pulse systems
    • G01S7/486—Receivers
    • G01S7/4861—Circuits for detection, sampling, integration or read-out
    • G01S7/4863—Detector arrays, e.g. charge-transfer gates
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88—Lidar systems specially adapted for specific applications
    • G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
    • G01S17/894—3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
    • 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
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14603—Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
    • 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
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14603—Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
    • H01L27/14607—Geometry of the photosensitive area
    • 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
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14609—Pixel-elements with integrated switching, control, storage or amplification elements
    • H01L27/14612—Pixel-elements with integrated switching, control, storage or amplification elements involving a transistor

Definitions

  • the present invention relates to a
  • Pixel structure for optical distance measurement on an object and on a distance detection system that such
  • Has pixel structure
  • Optical methods are known in the prior art, which recognize user actuations in response to an evaluation of image information and then e.g. Trigger switching operations. For example, here are automatic
  • pixels which record optical information in parallel, for example in the form of a CCD array.
  • DE 10 2008 025 669 A1 discloses an optical sensor which detects a gesture, whereupon a closing element of a vehicle is automatically moved.
  • WO 2008/116699 A2 relates to an optical sensor chip and relates to an optical pinch protection device for monitoring a window pane, sliding door or a tailgate in a motor vehicle
  • WO 2013/001084 A1 discloses a system for
  • Time-of-flight systems systems for optical distance detection are, depending on the evaluation method used, referred to as “time-of-flight” systems or also as “3D imager” or “range imager”.
  • ToF method a room area is illuminated with a light source and the runtime of the light reflected back from an object in the area with a surface sensor
  • the light source and sensor should be arranged as close as possible to each other.
  • the distance between sensor and target can be determined from the linear relationship between the time of light and the speed of light.
  • Detection unit i.e. the pixel array is pulsed sensitive
  • the integration window of the individual pixels is synchronized in time with the light source and limited in the integration duration.
  • This ToF acquisition method is not a purely image-based acquisition method.
  • a distance information is determined for each pixel, which is determined by the temporal
  • drift field detectors are a preferred sensor principle.
  • Pixel architecture based on the lateral drift field detector is in 6a and 6b.
  • the associated timing diagram is shown in FIG. 7.
  • At least two short-time integrators (TX1 / TX2) of different lengths and / or times are offset with the emission of a modulated electromagnetic wave
  • electromagnetic wave packets are accumulated in the first short-term integration window (TX1) and a second part in a second short-term integration window (TX2).
  • TX3 Short-term integrator
  • Short-term integrators TX1-TX3 realized by transfer gates that connect a photoactive area with the associated storage nodes FD1-FD3. To avoid being parasitic
  • the photoactive area is connected by a further transfer gate (TX4) to a discharge area DD which is permanently at a reference potential, so that charge carriers can be removed in a defined manner.
  • the photodetector is designed in such a way that an n-well is formed in the region of the photoactive region, which is formed by impurities, such as may be dominant on an Si-SiO 2 layer (gate oxide) by ap + Layer is removed, so that a low dark current results.
  • the n-well also has one
  • a preferred direction is permanently defined by connection to the corresponding control electrodes TX1-TX4. This is realized in such a way that three of the control electrodes are always connected to a low potential, so that potential barriers arise, while the remaining electrode is connected to a higher potential, so that any potential barrier is reduced and a preferred direction arises.
  • Attaching generated charge carriers related to extraneous light usually also results in an asymmetry (see FIG. 6a). This means that load carriers have to travel different ways to get to different storage nodes, which results in different time resolutions.
  • the pixel structure described is based on the knowledge that deviations (mismatches) with respect to one
  • Carrier transport can be reduced within one pixel in that the pixel comprises sub-pixels and a sub-pixel has a photoactive area and at least one evaluation capacity, which is designed to receive charge carriers generated in the photoactive area. Deviations from one
  • the ideal state (within manufacturing tolerances) can occur essentially identically for each sub-pixel and each evaluation capacity, so that deviations in the transfer properties between load carriers transported into the evaluation capacities can be reduced, which enables exact detection.
  • the pixel structure has at least one pixel which comprises a first sub-pixel, a second sub-pixel and a third sub-pixel.
  • the first sub-pixel comprises a first photoactive area, a first storage node and a first evaluation gate.
  • the first evaluation gate is formed adjacent to the first evaluation capacitance and the first photoactive region of the first sub-pixel and is designed to transport in the first
  • the second sub-pixel comprises a second photoactive area and a second storage node and a second evaluation gate, the second evaluation gate being adjacent to the second
  • Evaluation capacity and the second photoactive region of the second sub-pixel is formed.
  • the second evaluation gate is designed to control a transport of charge carriers generated in the second photoactive region from the second photoactive region to the second evaluation capacitance.
  • the third sub-pixel comprises a third photoactive area and a third storage node and a third evaluation gate.
  • the third evaluation gate is formed adjacent to the third evaluation capacitance and the third photoactive region of the third sub-pixel and is designed to transport charge carriers generated in the third photoactive region from the third photoactive area to the third evaluation capacity
  • the three sub-pixels are constructed similarly or identically, so that the charge carriers can be transported under the same conditions and with the same deviations for the sub-pixels and a deviation between the sub-pixels is small.
  • the object of the present invention is to create a pixel structure and a distance detection system that enable a signal-strong distance detection.
  • the taps (or associated signal lines) for querying the sub-pixels are short-circuited permanently or temporarily, in order to operate the sub-pixels as photoactive areas connected in parallel as required.
  • the partial pixels with their photoactive areas continue to be operated via their respective storage nodes and evaluation gates, as described in the mentioned publication DE 10 2014 2015 972 A1, but the accumulated charges are caused by the interconnection of the taps to be queried or
  • the advantages of designing a pixel with sub-pixels are basically retained, in particular, the divided photoactive areas are adapted to the assigned storage nodes and evaluation gates.
  • the separate detection of the sub-pixels and the associated reduced photoactive area can, however, be compensated for by connecting the signal lines as required.
  • the taps are those with the
  • Reading of the accumulated charges designated taps.
  • Amplifier circuit are arranged.
  • the signal lines can be permanently short-circuited or with a
  • controllable switching device can be short-circuited as required in order to short-circuit several sub-pixels at least temporarily on the output side and to evaluate them as a common pixel area. There are no essential ones for an evaluation circuit
  • the interconnected partial pixels are only suitable for recording one measurement per measurement cycle.
  • the measurement of the different light components is accordingly in several measurement cycles with the same
  • the first portion of the reflected light pulse and the second portion of the reflected light pulse are recorded in succession in individual measurement cycles with different timing requirements.
  • the device includes short-circuited or short-circuited ones
  • Taps a control circuit for controlling the pixel structure.
  • the control circuit is designed to include the evaluation gates of the sub-pixels in a first measurement cycle
  • Control interval (with a first delay compared to the radiation pulse), so that during the first
  • Control interval time-delayed second control interval (with a second delay compared to the radiation pulse), so that second charge carriers generated during the second control interval from the photoactive areas of the partial pixels with short-circuited taps to the respective assigned
  • Storage nodes are transported.
  • the partial pixels are then queried via the short-circuited taps of the partial pixels in order to record the registered amount of light in the second measurement cycle.
  • Control interval time-delayed third control interval (with a third delay compared to the radiation pulse), so that third charge carriers generated during the third measurement cycle by the photoactive ones of the partial pixels
  • control intervals can be completely (not overlapping in time) or partially
  • the signal strength is improved compared to operation with detection of the sub-pixels in a single measurement cycle.
  • the required measurement time increases in view of the required multiple measurement cycles. It is possible within the scope of the invention to use the sub-pixels for individual measurement cycles
  • control circuit is designed to include the discharge gates of the sub-pixels
  • Distance information of the object can be obtained or determined.
  • Distance detection system a pixel structure and one
  • Light source that is designed to emit a radiation pulse.
  • the photoactive areas of the sub-pixels are
  • a control circuit of the distance detection system is designed to a
  • Light source, the pixel structure and the control circuit are part of a common system.
  • the light source of a distance detection system is formed around which
  • a signal energy of the radiation pulse can be bundled in a short time interval, so that according to eye safety regulations a higher irradiance and thus a large difference between Signal energy and energy of the background light can be achieved in compliance with regulations.
  • FIG. 1 shows a schematic block diagram of a pixel structure for optical distance measurement on an object, in which a pixel has three sub-pixels according to an exemplary embodiment
  • Fig. 2 is a schematic block diagram of a
  • Pixel structure in which the pixel has the three sub-pixels that have the same function and the same elements according to one exemplary embodiment
  • Fig. 3 is a schematic block diagram of a device having a pixel structure and one with the pixel structure
  • FIG. 4 shows a schematic flow diagram of a method for determining the distance information, the reflectance information and a background light information according to one
  • Fig. 5 is a schematic block diagram of a
  • FIG. 6a shows a schematic top view of a pixel structure according to the prior art
  • Fig. 6b is a schematic cross-sectional view of the
  • FIG. 6a shows a schematic timing of a method for
  • Charge carriers are generated.
  • the charge carriers are transferred to storage nodes and, depending on the transfer gates
  • Embodiment transported to laxative areas.
  • evaluation gates describe transfer gates which are designed to control the transport of load carriers to a respective evaluation capacity.
  • removal gates relate to transfer gates which are designed to control the transport of load carriers to a respective removal area.
  • Laxation gates and evaluation gates can have the same design, so that the different designation only aims at the function for better differentiation.
  • Fig. 1 shows a schematic block diagram of a
  • the pixel structure 10 comprises a pixel 14 which has a first sub-pixel 16a, a second sub-pixel 16b and a third
  • the first sub-pixel 16a includes a photoactive area 18a that is configured to be based on of electromagnetic radiation 22r received by the photoactive region 18a to generate charge carriers.
  • the first sub-pixel 16a further comprises an evaluation gate 24a arranged on the photoactive region 18a and one on the evaluation gate 24a
  • the evaluation gate 24a is designed to remove the charge carriers generated in the photoactive region 18a from the photoactive in an active state
  • the electromagnetic radiation 22r can be generated based on a radiation pulse emitted in the direction of the object 12, wherein the
  • Radiation pulse can have a temporally variant intensity (for example on / off), so that the electromagnetic radiation 22r can also have a temporally variant intensity
  • the photoactive region 18a can be, for example
  • Electromagnetic radiation 22r can generate electron-hole pairs in the crystalline structure of the silicon semiconductor material. Due to the radiation of the electromagnetic radiation 22r, charge carriers can thus accumulate in the photoactive region 18a. H. are generated there.
  • the evaluation gate 24a can be formed, for example, as a transfer gate.
  • the evaluation gate can be controlled between at least two states, for example via a field effect. During an activation (switching on) or at the time by a
  • Conductive channel is realized by inversion of the semiconductor - the conductive channel can be designed so that an increasing potential profile arises in such a way that charge carriers of the photoactive region 18a to an electrode of this transfer gate, which is remote from the photoactive region 18a, are propagated and only cause a discharge of the potential there. This enables the photoactive to become impoverished
  • a control of the transport of the load carriers can, for example.
  • the evaluation gate 24a can be a switch element that
  • the closed state can also be referred to as the active state.
  • the evaluation gate 24a can be an element with a switch function that a direction of the
  • Controls cargo transport in a time-varying manner For example, a
  • Load carriers are transported to a discharge area if the evaluation gate is not activated (or activated) and the load carriers are transported to a storage node if the evaluation gate is activated (or not)
  • a transition between the activated and non-activated state can take place discretely or continuously.
  • the transport can take place through and / or laterally and / or in a height direction past the evaluation gate, so that, for example, a so-called draining-only structure is implemented.
  • the transport can therefore be based on the change, removal or creation of a potential barrier between the photoactive region and the storage node or others
  • the storage node 26a can be embodied as a floating diffusion region, as a capacitor or another capacitive element, for example by capacitive coupling and / or by an interconnection with metal-insulator-metal (MIM), metal-oxide Semiconductors (MOS), metal-metal capacitors or the like.
  • MIM metal-insulator-metal
  • MOS metal-oxide Semiconductors
  • the storage node 26a enables storage
  • the conversion into an electrical voltage can take place, for example, by degenerating the semiconductor, so that the floating diffusion can be fed to a readout circuit via Schottky contact.
  • Measuring node capacity can be called.
  • the storage node 26a is designed to receive and store charge carriers that are generated over a period of time in the photoactive region 18a. Charge carriers in the photoactive region 18a can lead to a variation of the
  • charge transfer based detectors such as Pinned, i.e., pinned photodiodes, lateral
  • Potential profile can be designed by suitable design of the detectors so that the maximum potential is in the storage node even without a (control) signal. This enables one
  • the storage node 26a can thus be a short-term integrator in connection with the photoactive area 18a and the evaluation gate 24a.
  • the storage node 26a can be referred to as evaluation capacity.
  • the second sub-pixel 16b has the same structure as the first sub-pixel 16a.
  • the second sub-pixel 16b comprises a photoactive area 18b, which has the same function as the photoactive area 18a.
  • the sub-pixel 16b furthermore has an evaluation gate 24b which is arranged adjacent to the photoactive region 18b and has the same function as the evaluation gate 24a.
  • the sub-pixel 16b further comprises a storage node 26b, which is arranged adjacent to the evaluation gate 24b and has the same function as the storage node 26a.
  • the third sub-pixel comprises a photoactive area 18c, which has the same function as the photoactive areas 18a and 18b.
  • the partial pixel 16c also has an evaluation gate 24c, which is adjacent to the photoactive region 18c
  • the sub-pixel 16c further comprises a storage node 26c, which is arranged adjacent to the evaluation gate 24c and has the same function as the storage nodes 26a and 26b.
  • Areas 18a, 18b and / or 18c can be, for example
  • Photogate structures are lateral third field detectors or
  • the output-side taps of the storage nodes 26a, 26b and 26c are, according to the invention, permanent or switchable and temporarily short-circuited, so that the charges accumulated in the storage nodes and the potentials generated therefrom can be tapped as a uniform signal and the sub-pixels as common sensor surface can be evaluated.
  • a common tap 27 is formed, which stores the storage nodes 26a, 26b and 26c for parallel reading and evaluation
  • Sub-pixels can be short-circuited, including controllable ones
  • Switching elements can be provided which temporarily short-circuit the taps of the sub-pixels.
  • the three sub-pixels are provided which temporarily short-circuit the taps of the sub-pixels.
  • Storage nodes 26a, 26b and 26c are transported and then available for common reading. Basically, only two of the sub-pixels can be on the output side
  • a distance 28 between the object 12 and the pixel structure 10 can be determinable for storage nodes 26a, 26b and 26c transporting charge carriers. This can be made possible, for example, by a difference in the transit time between the emission of electromagnetic radiation to the object 12 and the arrival of the (reflected) electromagnetic radiation
  • Radiation 22r is detected and / or evaluated.
  • a source of electromagnetic radiation may be adjacent to the pixel field, i.e. H. pixel structure 10, or at another location with a known distance and orientation angle with respect
  • the sub-pixels 16a, 16b and / or 16c can, when projected into a surface, be arranged in a planar manner, that is to say the sub-pixels 16a, 16b and / or 16c are at a distance from one another in at least one spatial direction.
  • the distance information with respect to the object 12 and with respect to the pixel 14 can thus be based on three spatially spaced photoactive ones
  • Storage nodes 26a, 26b and / or 26c can be obtained.
  • Distance information can thus describe the distance 28 with respect to an area of the photoactive regions 18a, 18b and / or 18c and an area in between.
  • the intermediate surface can be, for example, a surface that is spanned by the partial pixels 16a, 16b and / or 16c.
  • the distance 28 can be based on a reference point
  • the reference point can be a boundary point.
  • the reference point can be a
  • the pixel 14 can also be referred to as a super pixel or macropixel, which comprises the sub-pixels 16a, 16b and / or 16c.
  • Distance information for example with regard to the distance 28, of the object 12 to the pixel 14 can be obtained with respect to the three sub-pixels 16a, 16b and 16c, so that the distance 28 with respect to the pixel to a reference point, for example a geometric center between the sub-pixels 16a , 16b and / or 16c can be related.
  • the pixel 14 can comprise exactly three sub-pixels 16a, 16b and 16c. Alternatively, the pixel 14 can also comprise further sub-pixels.
  • Fig. 2 shows a schematic block diagram of a
  • Pixel structure 30 which has a pixel 32 with the three sub-pixels 16a, 16b and 16c, which have the same function and the same Have elements.
  • the same elements mean that a respective element has the same or comparable function.
  • the evaluation gate 24a (TX1) of the sub-pixel 16a, the evaluation gate 24b (TX2) of the sub-pixel 16c and the evaluation gate 24c (TX3) of the sub-pixel 16c this means, for example, that the evaluation gates 24a-c each as Transfergate are executable, the
  • Transfer gates can have a different structure or type, but each can have the same or similar behavior with regard to the switch function. Alternatively, the respective elements can also be formed identically.
  • the partial pixels 16a-c each have a photoactive one
  • the partial pixels 16a-c furthermore have the storage nodes 26a (FD1), 26b (FD2) and 26c (FD3).
  • An optional collector gate (collection gate CX) CX1, CX2 or CX3 is arranged adjacent to the photoactive regions 16a-c
  • Areas 18a-c generated charge carriers can be removed.
  • the respective evaluation gate 24a-c is on the respective one
  • a discharge gate TX4 is arranged on the collection gate CX1.
  • the removal gate TX4 like the evaluation gates 24a-c, is a switching element or a transfer gate.
  • the removal gate TX4 can be controlled in such a way that the charge carriers are transported from the photoactive region 18a to a removal area DD1 which is arranged on the removal gate TX4.
  • a potential UCG can be applied to the collection gates CX1-3 in order to control the collection gates.
  • Collection gates (CX1-3) enables the use of a
  • the collection gate (CX1-3) can be controlled in such a way that it is set to a suitable analog value is, so that a (possibly binary) change of a
  • Switching state can be omitted. In principle, they can
  • Transfer gates (TX1-6) also directly with the respective
  • Photoactive area 18a-c can be connected.
  • the evaluation gate TX1 and the discharge gate TX4 can be actuated at mutually different and / or overlapping times and / or time intervals, so that for example the evaluation gate TX1 or the discharge gate TX4 is closed, i. H. is conductive and the charge carriers are transported from the photoactive region 18a to the storage node 26a or to the discharge area DD1.
  • Subpixels 16a, 16b and 16c have the second subpixel 16b adjacent to the photoactive area 16b a collection gate CX2 and arranged thereon a discharge gate TX5 with a discharge region DD2 arranged thereon.
  • the third sub-pixel 16c has a collection gate CX3 adjacent to the photoactive region 18c and a discharge gate TX6 arranged thereon with a discharge region DD3 arranged thereon.
  • a first reference potential vddpixl can be applied to the first discharge area DD1, which means that the charge carriers from the
  • photoactive area 18a if the removal gate TX4 is conductive, can be at least partially removed from the photoactive area 18a via the removal area DD1.
  • the second discharge area DD2 can be connected to a second reference potential vddpix2, so that the charge carriers generated in the photoactive region 18b can be at least partially removed via the discharge area DD2 if the discharge gate TX5 is conductive.
  • a third reference potential vddpix3 can be applied to the third discharge area DD3, so that generated in the photoactive area 18c
  • Charge carriers can be at least partially removed via the discharge area DD3 if the discharge area TX6 is conductive.
  • the three reference potentials vddpixl, vddpix2 and vddpix3 can have mutually different potentials, for example more than 1 V, more than 3 V or more than 5 V.
  • a different electrical voltage (potential) can be one
  • Reference potentials vddpixl, vddpix2 and / or vddpix3 have the same potential value and are connected to one another, so that a common reference potential vddpix is formed.
  • the common reference potential vddpix enables the same flow rate of the charge carriers to the discharge areas DD1, DD2 and / or DD3.
  • the removal gates TX4, TX5 and TX6 can be controlled so that in each case in the photoactive areas 18a-c
  • the removal gates TX4, TX5 and TX6 can have a non-conductive state and the evaluation gates TX1,
  • TX2 or TX3 have a conductive state. This can be achieved by controlling the respective gates TX1-6.
  • the evaluation gate TX1 can be converted into a non-conductive state and the discharge gate TX4 into a conductive state, so that, in a first approximation, only those charge carriers to the
  • Storage nodes FD1 are transported during the measurement interval, which during the measurement interval in the photoactive
  • the evaluation gate TX1 can be activated, for example, by applying an electrical signal (potential) UTX1 to the evaluation gate TX1. For example, applying a high (high) potential of the voltage UTX1 can bring about the conductive state and applying a low (low) potential can cause another, for example non-conductive, state. Alternatively, the states (conductive / non-conductive) can also be mutually related with regard to the applied potentials (high / low) be reversed. In this way, the evaluation gate TX2 can also be activated by means of a signal UTX2 and the evaluation gate TX3 can be activated by means of a signal UTX3.
  • the discharge gates TX4-6 can be controlled by means of signals UTX4- UTX6.
  • Metal oxide semiconductors For example, is a
  • the reset potential FD1 can be applied.
  • drain connection drain connection
  • Reset transistor Ml-1 is, for example, a
  • the emptying or resetting enables a new quantity of charge to be taken up in a future one
  • the reset transistor M1-1 can also be designed as another switching element, for example as a
  • an evaluation area of the storage node FD2 of the second sub-pixel 16b can be connected to a reset potential Reset FD2 via a reset transistor Ml-2.
  • a reference potential vddpixö can be applied to the reset transistor Ml-2.
  • the third sub-pixel 16c has one
  • Reset transistor Ml-3 with a gate connection to which a third reset potential reset FD3 can be applied.
  • the drain of the reset transistor Ml-3 is connected to a
  • Reference potential vddpixö connectable.
  • the reference potentials vddpix4, vddpixö and vddpixö can be interconnected and have the same value, i. H. have the same potential.
  • the reference potentials vddpixl, vddpix2, vddpix3, vddpix4, vddpixö and / or vddpixö can be linked together
  • a gate connection of an amplifier transistor M2-1 is connected between the storage node FD1 and the reset transistor M1-1 of the first sub-pixel 16a.
  • a drain connection of the amplifier transistor M2-1 can be connected to a supply potential vdda-HV.
  • a bulk terminal of the amplifier transistor M2-1 is connected to the reference potential (ground).
  • a source connection of the amplifier transistor M2-1 is connected to a drain connection of a selection switch M3-1 in the form of a MOS transistor.
  • the sub-pixels 16b and 16c have an amplifier transistor M2-2 or M2-3 and a selection transistor M3-2 or M3-3.
  • a gate connection of the selector switch M3-1 has a selection potential Row select can be connected, the same applies to the selection switches M3-2 and M3-3.
  • Selection switch M3-1 which is short-circuited with selection switches M3-2 and M3-3 of the other two subpixels, is on
  • Evaluation potential (measuring voltage Uout) can be tapped. Since the source connections are short-circuited, the evaluation of the partial pixels takes place despite being separately controllable and separate
  • Row selection on the drain connections of the selection switches M3-1, M3-2 and M3-3 enables tapping of the amplified
  • Operation of sub-pixels 16a, 16b and 16c may include two or more time intervals that are repeated cyclically.
  • a first time interval by means of the actuation of the reset transistors Ml-1, Ml-2 and Ml-3, an outflow of
  • Charge carriers from the storage nodes FD1, FD2 and FD3 are made possible synchronously.
  • the reset transistors Ml-1, Ml-2, Ml-3 cannot be turned on, so that the potential or signal Uout is obtained. If storage nodes are not or only partially reset between cycles, charge carriers stored in previous cycles can be retained. This enables the charge carriers to be averaged over two or more cycles, which can lead to a reduction in measurement noise. Alternatively, an evaluation and a reset can take place in each cycle.
  • amplifier transistors M2-1, M2-2 and M2-3 another amplifier circuit, for example a differential amplifier or operational amplifier, can also be arranged.
  • the illustrated connection of the reset transistors Ml-1, Ml-2, Ml-3, the amplifier transistors M2-1, M2-2, M2-3 and the selection transistors M3-1, M3-2 and M3-3 is only shown as an example.
  • another one can be used
  • Interconnection can be arranged that a reset and / or
  • transistors and gates are MOS-based
  • bipolar transistors with an insulated gate connection can be arranged, which have a complementary gate connection, a collector and an emitter connection.
  • junction-FET-JFET bipolar transistors and / or junction field-effect transistors
  • the pixel structure 30 has been described in such a way that the optional collection gates (CX1-3) are arranged, the pixel structure 30 can also be implemented in whole or in part without it.
  • An arrangement of this type has the advantage that a detected object or a region of the detected
  • Sub-pixels 16a-c can be reduced or reduced.
  • Fig. 3 shows a schematic block diagram of a
  • Control circuit 54 which is connected to the pixel 32.
  • the control circuit 54 is
  • control circuit 54 configured to receive signals, potentials and / or currents from the pixel 32 and to drive the pixel 32, for example by the control circuit 54 being configured to reset the signals FD1-3, row selection, UTX1-UTX3 and / or UTX4- UTX6, as described in FIG. 3, to be applied to the device 60. 3, the control circuit 54 may be configured to receive the signal Uout from the pixel 32. The control circuit 54 is configured to based on an amount of the charge carriers that are in the photoactive Regions 18a-c are generated to determine distance information with respect to the object 12.
  • a light source 56 can be designed to emit the electromagnetic one
  • Electromagnetic radiation 22r is at least partially reflected by the object 12 and received by the pixel 32.
  • Control circuit 54 may be configured, for example, to
  • Fig. 4 shows a schematic flow diagram of a
  • Reflectance information and background light information as can be carried out by the control circuit 54.
  • the graphs 710 and 720 schematically show a normalized energy level E of a light source on a respective ordinate
  • An energy level 58a denotes an energy of one
  • Backlight for example at the location of the light source.
  • Energy level 58b also denotes an energy level of the background light, for example at the location of the pixel structure.
  • the graphs 730 to 790 each have a normalized one
  • Graph 790 shows a summarized signal “reset FDs” (ie reset of the storage nodes), which exemplarily means a common activation of the signals reset FD1, reset FD2 and reset FD3 in FIG. 3.
  • the activation of one or more reset signals reset FD1-reset FD3 can also be done individually.
  • the light pulse is emitted again for each measurement cycle according to graph 710.
  • the required three measurement cycles take place in such a short period of time that, in a first approximation, the timing of the reflected light pulse according to graph 720 remains unchanged for each of the measurement cycles, since the measured object does not move in the first approximation during this period.
  • Graphs 730 and 740 show the signals in a first measurement cycle.
  • Graphs 750 and 760 show the signals in a second measurement cycle.
  • Graphs 770 and 780 show the signals in a third measurement cycle.
  • control circuit 54 is designed to enable the storage nodes to drain charge carriers from the storage nodes FD1-3 by applying the reset FDs signal. Furthermore, the control circuit 54 is designed to provide the signals UTX4, UTX5 and UTX6, so that in the photoactive areas 18a-c generated charge carriers to the
  • Discharge areas DD1-3 can be transported.
  • the control circuit 54 is synchronized in time with the light source 56.
  • the light source 56 is designed to emit the electromagnetic radiation 22 in the form of a light pulse with a time duration T p ,
  • control circuit 54 based on control by control circuit 54 or other device.
  • the end of the light pulse is indicated at time t5 on the time axis.
  • the control circuit 54 is designed to switch the evaluation gates TX1, TX2, TX3 into a conductive state and the discharge gates TX4, TX5, in a first measurement cycle, shown in graphs 730 and 740, during the time interval (t3-t5). To bring TX6 into a non-conductive state, so that in the
  • photoactive areas 18a, 18b, 18c generated charge carriers can be transported into the storage nodes FD1, FD2, FD3 and the corresponding signal U outi can be obtained at the common tap.
  • the sub-pixels are reset and the timer is restarted.
  • the control circuit 54 is designed to conduct the evaluation gates TX1, TX2 and TX3 in a second measurement cycle during a time interval (t5-t7) which follows the time interval (t3-t5) directly with respect to the emitted light pulse
  • Laxation gates TX4, TX5, TX6 should not be turned on so that charge carriers generated in the photoactive areas 18a, 18b, 18c can be transported into the storage nodes FD1, FD2, FD3 and the signal U out 2 can be obtained for the second measurement cycle.
  • the electromagnetic radiation 22r that is, the
  • Light pulse arrives with a time delay relative to the time t3 and reflects from the object 12 at the pixel 32.
  • the time of flight (English: Time of Flight ToF) i oF can be the time between the emission of the light pulse 22 at the light source 56 to
  • the reflected light pulse 22r causes charge carriers to be generated in the photoactive regions 18a, 18b and 18c.
  • the time t5 follows the time t4, the time t5 being arranged on the time axis before the time t6.
  • a time t7 follows the time t6.
  • a hatched area 62a denotes a measure of charge carriers which are generated in the first measurement cycle in the photoactive areas 18a, 18b, 18c and to the storage nodes FD1, FD2, FD3
  • a hatched area 62b describes a measure of charge carriers that is in the photoactive areas 18a
  • 18b and 18c are generated and transported to the storage nodes FD1, FD2, FD3 or an amplitude of the signal U out 2 of the second measurement cycle.
  • the control circuit When the third measurement cycle, shown in graphs 770 and 780, is carried out in a control interval between two times t1 and t2, the control circuit is designed to provide the signals UTX1, UTX2, UTX3 and at the same time to deactivate and deactivate the signals UTX4, UTX5 and UTX6 to switch the discharge gates TX4, TX5, TX6 into a blocking state.
  • the control circuit 54 is
  • control circuit 54 is designed to be based on the drive interval (tl-t2)
  • charge carriers which are generated based on background radiation in the photoactive regions 18a, 18b and 18c can also be transported to the storage nodes FD1, FD2 and FD3 and the signals U outi im first and U out 2 in the second measurement cycle
  • the background light information can relate to the detected object area, for example scattered light, which strikes the photoactive areas independently of the light source 56.
  • the control device 54 is designed for this
  • Correct measurement cycle This can be done, for example, by subtracting the signal levels.
  • the execution of the three measurement cycles corresponds to a complete measurement, and a multiple of the three
  • Measuring cycles can be carried out to average the
  • adjusted ( adjusted) hatched areas 62a and 62b can be calculated by the control device 54, for example, in order to determine a total energy of the reflected light pulse. Is the control device 54 information regarding a
  • Energy strength of the emitted light pulse of the light source 56 can be provided, for example by subtraction or a division a measure of the reflectance of the object 12 can be obtained.
  • the sum of the shaded areas 62a and 62b (possibly cleaned from the backlight) or the signals U out of the first measurement cycle and U out of the second measurement cycle can reflect the total energy of the reflected light
  • a proportion of the total energy of the reflected light pulse in relation to the total energy of the emitted light pulse can show which proportion of the emitted light pulse is reflected by the object 12, that is to say contain the reflectance information.
  • the control intervals (tl-t2), (t3-t5) and (t5-t7) can be the same or
  • the control circuit 54 is designed to relate the signals U outi of the first measurement cycle and U out 2 of the second measurement cycle to one another, for example by means of a
  • Background radiation / background light cleaned or not cleaned can provide information about which portions of the reflected light pulse are received by the pixel 32 in the time interval (t3-t5) and in the time interval (t5-t7).
  • the synchronization of the time intervals (t3-t5) and (t5-t7) enables the transit time T oF to be determined .
  • the transit time i oF can be, for example, in one of the
  • the distance d can be used in the present case
  • control intervals (t3-t5), (t5-t7) and (tl-t2) have been described in such a way that they are temporal
  • Control intervals (t3-t5), (t5-t7) and (tl-t2) can also be arranged to overlap completely or partially in time. Detection of two independent signals (graphs 730 and 740) or three independent signals (graphs 730, 740 and 750) enables the distance and reflectance information or additionally the background light information to be determined. Furthermore, the
  • Control intervals (t3-t5), (t5-t7) and (tl-t2) have the same length or a different length.
  • Fig. 5 shows a schematic block diagram of a
  • Distance detection system 90 which includes the pixel structure 30, the control circuit 54, which is coupled to the pixel structure 30, and the light source 56.
  • the control circuit 54 and the light source 56 are connected to one another, so that the control circuit 54 and the light source 56 can be easily synchronized. This can be done, for example, by a
  • the light source 56 is adjacent to the pixel structure 30
  • a transit time of the radiation pulse from the light source 56 to the object 12 is essentially the same as a transit time of the reflected radiation pulse from the object 12 to the pixel structure 30.
  • the light source 56 can also be arranged at a distance from the pixel structure 30.
  • the distance detection system 90 can be designed to use the light source 56 to transmit the radiation pulse 22 with a
  • a total of radiation pulses can have a duty cycle of less than or equal to 50% based on one
  • a duty cycle of one percent means, for example, that a cycle or interval with a length of, for example, 30 ps has a pulse with a width of 30 ns and a further pulse is transmitted after 2970 ns.
  • a pulse duration of 30 ns can be derived, for example, from a pulse duty factor of 1/3000, which can be influenced by eye safety criteria, and a detection range of 4.5 m.
  • the electromagnetic radiation 22 can emit radiation pulses with a small duty cycle and therefore pulsed transit times
  • 6a shows a schematic plan view of a
  • Pixel structure 110 according to the prior art. On one
  • photoactive area 92 is three
  • Storage nodes FD1, FD2 and FD3 and a discharge area DD are arranged.
  • 6b shows a schematic cross-sectional view of the pixel structure 110.
  • 6a and 6b show a schematic of a ToF pixel based on a lateral drift field photodiode
  • FIG. 6a showing a top perspective
  • FIG. 6b a cross section along the transfer direction of the pixel.
  • FIG. 7 shows a schematic timing of a method for evaluating the pixel structure 110 according to the prior art, which can be iterated multiple times if necessary in order to
  • This time scheme is similar to the scheme described above with reference to FIG. 4, but in which the sub-pixels are jointly evaluated for detection, while here a single photoactive area is operated with several storage nodes.

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  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
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Abstract

La présente invention concerne une structure de pixels (10; 30) destinée à la mesure de distance optique sur un objet (12), comprenant au moins un pixel (14; 32), qui comporte une pluralité de pixels partiels (16a, 16b, 16c), chaque pixel partiel (16a, 16b, 16c) comportant une première zone photoactive (18a, 18b, 18c), un premier nœud de mémorisation (26a, FD1, 26b, FD2, 26c, FD3) et une première passerelle d'évaluation (24a, TX1, 24b, TX2, 24c, TX3), la première passerelle d'évaluation (24a, TX1, 24b, TX2, 24c, TX3) étant adjacente au premier nœud de mémorisation (26a, FD1, 26b, FD2, 26c, FD3) respectif et à la première zone photoactive (18a, 18b, 18c), et étant conçue pour commander un transport de porteuses de charge de la première zone photoactive (18a, 18b, 18c) au premier nœud de mémorisation (26a, FD1, 26b, FD2, 26c, FD3); un circuit amplificateur (M2-1, M2-1, M2-3) connecté au nœud de mémorisation (26a-c, FD1-3) respectif étant formé, qui est court-circuité, par au moins deux nœuds de mémorisation, en permanence ou temporairement, du côté sortie de telle sorte que les nœuds de mémorisation peuvent être lus à l'aide d'une seule prise.
PCT/EP2019/085700 2018-12-18 2019-12-17 Structure de pixels destinée à la mesure de distance optique sur un objet et système de détection de la distance associé WO2020127304A1 (fr)

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US20060192938A1 (en) * 2003-02-03 2006-08-31 National University Corporation Shizuoka University Distance image sensor
WO2008116699A2 (fr) 2007-03-23 2008-10-02 Continental Automotive Gmbh Puce de capteur optique et dispositif de sécurité antipincement optique doté d'une telle puce
DE102008025669A1 (de) 2007-06-01 2008-12-11 GM Global Technology Operations, Inc., Detroit Fahrzeugschliesseinrichtungsbetätigungsvorrichtung und Verfahren für nicht freie Hände
WO2013001084A1 (fr) 2011-06-30 2013-01-03 Johnson Controls Gmbh Dispositif et procédé de détection sans contact d'objets et/ou de personnes ainsi que de gestes et/ou de processus de commande exécutés par eux
US20140253688A1 (en) * 2013-03-11 2014-09-11 Texas Instruments Incorporated Time of Flight Sensor Binning
DE102014215972A1 (de) 2014-08-12 2016-02-18 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Pixelstruktur zur optischen Abstandsmessung an einem Objekt und Abstandserfassungssystem mit einer derartigen Pixelstruktur

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US20060192938A1 (en) * 2003-02-03 2006-08-31 National University Corporation Shizuoka University Distance image sensor
WO2008116699A2 (fr) 2007-03-23 2008-10-02 Continental Automotive Gmbh Puce de capteur optique et dispositif de sécurité antipincement optique doté d'une telle puce
DE102008025669A1 (de) 2007-06-01 2008-12-11 GM Global Technology Operations, Inc., Detroit Fahrzeugschliesseinrichtungsbetätigungsvorrichtung und Verfahren für nicht freie Hände
WO2013001084A1 (fr) 2011-06-30 2013-01-03 Johnson Controls Gmbh Dispositif et procédé de détection sans contact d'objets et/ou de personnes ainsi que de gestes et/ou de processus de commande exécutés par eux
US20140253688A1 (en) * 2013-03-11 2014-09-11 Texas Instruments Incorporated Time of Flight Sensor Binning
DE102014215972A1 (de) 2014-08-12 2016-02-18 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Pixelstruktur zur optischen Abstandsmessung an einem Objekt und Abstandserfassungssystem mit einer derartigen Pixelstruktur

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