High Quantum Efficiency Geiger Mode Avalanche Diodes and Arrays Thereof Comprising High-Sensitivity Photon Mixing Structures

Abstract

A photodetector device includes a semiconductor material layer and at least one photodiode in the semiconductor material layer. The at least one photodiode is configured to be biased beyond the breakdown voltage of the at least one photodiode to generate a corresponding electrical signal in response to detecting incident photons. The corresponding electrical signal is independent of the optical power of the incident photons. A textured region is coupled to the semiconductor material layer and the textured region includes an optical structure that is positioned to interact with the incident photons when the at least one photodiode detects the incident photons. Two or more photodiodes may define a pixel of the photodetector device, and the optical structure may be configured to direct the incident photons to any one of the two or more photodiodes of the pixel.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority benefit of U.S. Provisional Patent Application No. 62 / 752,718, filed on October 30, 2018, entitled "High Quantum Efficiency Geiger - Mode Avalanche Diodes and Arrays Thereof", and U.S. Provisional Patent Application No. 62 / 775,105, filed on December 4, 2018, entitled "High Sensitivity Photon Mixing Structures", with the U.S. Patent and Trademark Office. The disclosures of Patent Application No. 62 / 752,718 and Patent Application No. 62 / 775,105 are incorporated herein by reference. Technical field

[0003] The subject matter herein generally relates to image sensors, and more particularly to image sensors for imaging in LIDAR (Light Detection and Ranging) systems. Background art

[0004] Time - of - Flight (ToF) based imaging is used in many applications including ranging, depth profiling, and 3D imaging (e.g., Light Detection and Ranging (LIDAR), also referred to herein as lidar). ToF 3D imaging systems can utilize direct ToF (dToF) measurements (where the length of time between transmitting an optical signal and sensing or detecting the optical signal after reflection from an object or other target is measured to determine distance) or indirect ToF (iToF) measurements (where the amplitude of the transmitted optical signal is modulated and the phase delay or phase shift of the reflected optical signal is measured, and the time for the signal to travel to and from the object results in a phase shift that is proportional to the distance traveled). However, to illuminate a large Field of View (FoV) (which can include long distances and / or low - reflectivity targets under bright ambient light conditions) and receive recognizable returned or reflected optical signals (also referred to herein as echo signals) therefrom, higher optical emission power (and thus higher power consumption) may be required.

[0005] In some applications such as lidar, it may be desirable to detect both very dark and very bright echo signals. For example, a 10% Lambertian reflecting target at a distance of 200 meters (m) can reflect 1 / 200 of the light reflected by a similar target at a distance of 1 m 2 , and can reflect 1 / (10×200) of the light reflected by a 100% Lambertian reflecting target at a distance of 1 m 2), and can reflect light reflected by a strong retroreflective target within a distance range of 1 m by approximately 1 / (1000×200 2 ) = 1 / 40,000,000. The distance range can refer to the distance between the target and the lidar detector array. Since some electronic circuits may have a fixed gain-bandwidth product, it may be difficult to detect both very dark and very bright targets with very high temporal accuracy.

[0006] Some conventional photodetector devices (such as those described in U.S. Patent Application No. 2012 / 0146172) can have a current responsivity proportional to the irradiance or incident optical power, such as 0.4 A / W. Such devices may thus have a limited ability to detect very dark and very bright objects. The detection range between a dark object and a bright object can be referred to as the dynamic range of the device. Such conventional photodetector devices typically generate an analog signal in response to detecting an arriving optical signal. The analog signal can typically be sampled above the Nyquist frequency, or at least twice the bandwidth of the desired information. Such sampling can be expensive, difficult to parallelize, and / or may draw a large amount of power (e.g., in terms of the occupied area or "active area" on the device).

[0007] To increase the sensitivity of a photodetector, some conventional photodetector devices can include a surface modification of silicon to reduce reflectivity and increase the wavelength range of light absorption, also known as a "black silicon" layer, as described, for example, in U.S. Patent No. 8,679,959. Light trapping structures can also be used to increase the absorption probability. For example, some conventional diffractive light trapping structures are described in "IR sensitivity enhancement of CMOS Image Sensor with diffractive light trapping pixels" by Yokogawa et al. SUMMARY OF THE INVENTION

[0008] According to some embodiments, a photodetector device includes a semiconductor material layer and at least one photodiode in the semiconductor material layer, the at least one photodiode being configured to be biased beyond the breakdown voltage of the at least one photodiode to generate a corresponding electrical signal in response to detecting an incident photon, wherein the corresponding electrical signal is independent of the optical power of the incident photon. A textured region is coupled to the semiconductor material layer and the textured region includes an optical structure that is positioned to interact with the incident photon when the at least one photodiode detects the incident photon.

[0009] In some embodiments, at least one photodiode includes two or more photodiodes that define a pixel of a photodetector device, and the optical structure is configured to direct incident photons to any one of the two or more photodiodes of the pixel for detection thereby.

[0010] In some embodiments, corresponding isolation regions separate the pixel from adjacent pixels of the photodetector device, and the pixel does not have a corresponding isolation region between its two or more photodiodes.

[0011] In some embodiments, the corresponding isolation regions include corresponding deep trench isolation (DTI) regions. A shallower trench isolation (SrTI) structure is provided between two or more photodiodes in the pixel, wherein the corresponding DTI regions protrude away from the two or more photodiodes beyond the SrTI structure.

[0012] In some embodiments, in response to incident photons being detected by any one of the two or more photodiodes, a corresponding electrical signal generated by any one of the two or more photodiodes is configured to be output to a corresponding processing path, and the corresponding processing path includes corresponding electronic circuit elements not shared by the two or more photodiodes of the pixel.

[0013] In some embodiments, the readout wafer includes corresponding electronic circuit elements, and a semiconductor material layer is stacked on the surface of the readout wafer.

[0014] In some embodiments, the corresponding electronic circuit elements include corresponding quenching circuits and / or recharge circuits.

[0015] In some embodiments, a metal layer structure is disposed adjacent to the surface of the readout wafer in the readout wafer. The metal layer structure extends along and under two or more photodiodes, and the metal layer structure is configured to provide an electrical signal to the two or more photodiodes or provide an electrical signal from the two or more photodiodes.

[0016] In some embodiments, the corresponding electronic circuit elements include an analog time integrator or an analog counter, and the metal layer structure includes integrating or counting capacitors for the analog time integrator or the analog counter.

[0017] In some embodiments, the optical structure is configured to direct incident photons away from one of the two or more photodiodes of the pixel before detection by any one of the two or more photodiodes.

[0018] In some embodiments, the optical structure is a diffractive element, and the diffractive element includes one or more dimensions that are each less than the wavelength of the incident photons. In some embodiments, the diffractive element can be an inverted pyramid array (IPA) structure.

[0019] In some embodiments, at least one of two or more photodiodes in the pixel is configured to be independently disabled in response to a control signal in some embodiments, and the control signal is generated in response to a corresponding electrical signal output therefrom.

[0020] In some embodiments, a trench isolation region separates the pixel from adjacent pixels of the photodetector device. The first electrode and the second electrode are configured to apply a reverse bias to at least one of two or more photodiodes of the pixel based on a voltage difference between the first electrode and the second electrode, wherein the voltage difference can be switched between a first voltage greater than the breakdown voltage and a second voltage less than the breakdown voltage.

[0021] In some embodiments, the at least one photodiode includes at least one single photon avalanche detector (SPAD), and the at least one single photon avalanche detector (SPAD) has a corresponding semiconductor junction, and the semiconductor junction includes a substantially planar region and a guard ring structure at an edge of the region.

[0022] In some embodiments, the photodetector device is an optical sensor array, and the optical sensor array includes at least one photodiode between its multiple pixels. The optical sensor array is a light detection and ranging (LIDAR) detector array, and the source of the incident photons is a LIDAR transmitter array.

[0023] According to some embodiments, the optical sensor array includes a plurality of pixels, corresponding isolation regions, and an optical structure; each of the plurality of pixels includes two or more photodiodes configured to generate corresponding electrical signals in response to incident photons, wherein the corresponding electrical signals are independent of the optical power of the incident photons; the corresponding isolation regions separate adjacent pixels among the pixels; the optical structure is positioned between the corresponding isolation regions and the optical structure is configured to direct the incident photons to any one of the two or more photodiodes of each pixel in the pixels.

[0024] In some embodiments, each pixel in the pixels does not have a corresponding isolation region between two or more photodiodes of the pixel, and the optical structure is configured to direct the incident photons away from one of the two or more photodiodes of each pixel in the pixels before detection by any one of the two or more photodiodes.

[0025] In some embodiments, the corresponding isolation regions include corresponding deep trench isolation (DTI) regions. A shallower trench isolation (SrTI) structure extends between two or more photodiodes in a pixel, wherein the corresponding DTI regions protrude away from the two or more photodiodes by more than the SrTI structure.

[0026] In some embodiments, the optical structure is a diffractive element that respectively includes one or more dimensions smaller than the wavelength of incident photons. The diffractive element is configured to direct the incident photons to any one of the two or more photodiodes in each pixel of the pixel with an optical path length greater than the distance between the surface of the optical sensor array and one of the two or more photodiodes.

[0027] In some embodiments, the two or more photodiodes respectively include a semiconductor junction that includes a substantially planar region and a guard ring structure at the edge of the region. The semiconductor junction is configured to be biased beyond its breakdown voltage to generate a corresponding electrical signal in response to incident photons.

[0028] In some embodiments, in response to incident photons being detected by any one of the two or more photodiodes, the corresponding electrical signal generated by any one of the two or more photodiodes is configured to be output to a corresponding processing path, and the corresponding processing path includes corresponding electronic circuit elements not shared by the two or more photodiodes in each pixel of the pixel.

[0029] In some embodiments, the pixel, the corresponding isolation region, and the optical structure are disposed in or on a first semiconductor layer, and the second semiconductor layer includes the corresponding electronic circuit elements. The first semiconductor layer is bonded to the surface of the second semiconductor layer.

[0030] In some embodiments, the second semiconductor layer further includes a controller configured to receive the corresponding electrical signals generated by the two or more photodiodes in each pixel of the pixel and perform a time correlation between the corresponding arrival times indicated by the corresponding electrical signals.

[0031] In some embodiments, the optical sensor array is a light detection and ranging (LIDAR) detector array, and the source of the incident photons is a flash LIDAR transmitter array.

[0032] In some embodiments, the optical sensor array is a light detection and ranging (LIDAR) detector array, and the source of the incident photons is a scanning LIDAR transmitter array.

[0033] According to some embodiments, a light detection and ranging (LIDAR) detector array includes: a semiconductor material layer, a plurality of pixels, corresponding deep trench isolation regions, a first contact and a second contact, and a diffractive optical element; the semiconductor material layer has a thickness of from about 1 μm to about 100 μm; the plurality of pixels are in the semiconductor material layer, and each pixel includes at least one photodiode defined by a semiconductor junction, the semiconductor junction includes a substantially planar region and a guard ring structure at an edge of the region, and the semiconductor junction is configured to generate an electrical signal in response to incident photons having a wavelength between about 800 nanometers (nm) and about 1200 nm when a reverse bias applied to the semiconductor junction exceeds the breakdown voltage of the semiconductor junction, wherein the electrical signal is independent of the optical power of the incident photons; the corresponding deep trench isolation regions separate adjacent pixels among the pixels; the first contact and the second contact are adjacent to the corresponding deep trench isolation regions in each pixel, wherein the first contact and the second contact are configured to apply a reverse bias to the semiconductor junction based on the voltage difference between them; the diffractive optical element is positioned between the pixels and a source of incident photons.

[0034] Upon reviewing the following drawings and detailed description, other devices, apparatuses, and / or methods according to some embodiments will become apparent to those skilled in the art. All such additional embodiments, in addition to any and all combinations of the above embodiments, are intended to be included within this specification, within the scope of the present invention, and protected by the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1A 、 Figure 1B and Figure 1C are cross-sectional views showing an exemplary photodetector device according to some embodiments of the present invention.

[0036] Figure 2A and Figure 2B are cross-sectional views showing an exemplary photodetector device in which each pixel includes a plurality of photodiodes according to some embodiments of the present invention.

[0037] Figure 3 is a cross-sectional view showing an exemplary photodetector device including a shallow isolation structure between a plurality of photodiodes in each pixel according to some embodiments of the present invention.

[0038] Figure 4 is a cross-sectional view showing an exemplary photodetector device stacked on a readout wafer according to some embodiments of the present invention.

[0039] Figure 5 is a cross-sectional view showing an exemplary photodetector stacked on a readout wafer including a capacitor structure according to some embodiments of the present invention.

[0040] Figure 6A and Figure 6B is a block diagram showing an example lidar system or circuit and related components according to some embodiments of the present invention. Detailed implementation

[0041] An enhanced-sensitivity CMOS image sensor can be designed to improve the sensitivity of the CMOS image sensor by forming a sub-wavelength diffractive light-trapping structure (such as an inverted pyramid array (IPA) structure), which refracts incident light sufficiently normally at an angle such that it undergoes total internal reflection from a deep trench isolation (DTI) structure that separates each pixel from its adjacent pixels. This light travels a longer path in silicon compared to similar normally incident light without a diffractive light-trapping structure. The longer path can increase the probability of absorption and thus increase the sensitivity of the device. The DTI structure prevents photons from irradiating above one pixel to generate charge that would be collected in an adjacent pixel.

[0042] Such a conventional device can include a photodetector device having a current responsivity proportional to the optical power of incident photons, such that the incident optical power is converted into a proportional current. Such a photodetector device (also referred to as a sub-Geiger photodiode, sub-Geiger avalanche photodiode, or avalanche photodiode (APD)) can have a limited dynamic range. For example, when operating at or near the breakdown voltage in the planar region of the diode, at the breakdown voltage in the planar region of the diode, or above the breakdown voltage in the planar region of the diode, the sub-Geiger photodiode cannot operate above the breakdown voltage due to a non-planar semiconductor junction region that may be prone to premature breakdown, which may cause damage or reduced reliability. In a typical implementation of such a sub-Geiger photodiode, the time responsivity may also be less accurate, thus limiting the ability of such a sensor to accurately measure the arrival time of photons.

[0043] In contrast, embodiments of the present invention provide a high quantum efficiency photodetector device and / or a high sensitivity photodetector device including a Geiger mode photodiode, which can generate an electrical signal independent of the optical power of incident photons. Some embodiments described herein are directed to a single photon avalanche diode (SPAD), which is also referred to as a Geiger mode avalanche diode. Specific embodiments relate to silicon SPADs, but the present invention is not limited to silicon and can thus be applied or generalized to include other semiconductor materials. That is, while described with reference to silicon, embodiments of the present invention can be implemented in other semiconductor materials suitable for incorporation into optoelectronic devices.

[0044] In the operation of a Geiger-mode avalanche diode, a reverse bias exceeding the breakdown voltage of the diode is applied to create an electric field of sufficient magnitude such that a single charge carrier introduced into the depletion region of the device can be accelerated to the point where it carries enough kinetic energy to generate secondary charge pairs through a process known as impact ionization. In this way, a single absorbed photon can trigger a self-sustaining ionization cascade that will spread throughout the junction subjected to the electric field, which will break down and become conductive, effectively amplifying the original electron-hole pair into a current. The avalanche can be quenched actively or passively by a quenching circuit that reduces the reverse voltage sustained by the diode to a value below its breakdown voltage, thus stopping the avalanche to allow the device to "reset" for further photon detection.

[0045] The initial charge carrier can be generated photoelectrically by a single incident photon striking the high-field region. This single-photon detection mode of operation is commonly referred to as the 'Geiger mode'. A single SPAD sensor operating in the Geiger mode acts as a photon-triggered switch in either the 'on' or 'off' state, which results in a binary output, regardless of the number of photons simultaneously absorbed within the diode, and it will produce a signal indistinguishable from that of a single photon.

[0046] Various embodiments of Geiger-mode devices can operate in a front-side illumination mode. Due to the lower absorption coefficient of silicon at red and near-infrared wavelengths, many of these devices may suffer from a low photon detection probability (PDP) of approximately less than 1 percentage point or less than a few percentage points. This deficiency can be addressed in part by forming deeper and / or wider junctions in the silicon. However, deeper and / or wider depletion-region junctions are typically less doped and may thus suffer from breakdown voltage non-uniformity, especially across a device array. Additionally, as the diameter and / or volume of the depletion and / or multiplication region of these devices increases, the timing resolution can increase, which can translate into a broader jitter in the timing of subsequent avalanches. Similarly, when the electrical path from the anode or cathode node to the junction increases or when the electrical path from the anode or cathode node to the junction is curved, the series resistance can increase and the time required to quench the avalanche and the power consumed during the avalanche can increase. Even with a deeper junction, the PDP may be low, e.g., 2%.

[0047] Grinding the backside of the wafer to an appropriate thickness and illuminating from the backside can increase the interaction length between photons and silicon, and thus increase the absorption probability of long-wavelength photons. A wafer thickness of about 3 - 6 microns has been demonstrated. The thin wafer can be bonded to a second CMOS wafer that contains the circuitry required for the correct operation of the device. However, even these backside-illuminated devices typically only provide a limited PDP, e.g., 4%. Further expansion of the absorption region may result in optical crosstalk due to charge diffusion into neighboring pixels. This diffusion can be reduced by generating an electric field that can partially contain these charges, but the ability to confine photo-generated charges decreases as the depth of the silicon substrate increases. Also, while some devices can include an anti-reflection (AR) coating to increase sensitivity, and / or can include a metallization layer behind the photodiode to increase the effective optical path length of photons in silicon, photons incident perpendicular to the surface of the SPAD can continue to travel on the same trajectory (e.g., without diffraction) and thus may not be given a higher absorption probability.

[0048] Some embodiments of the present invention provide a photodetector device and a sensor array that include a Geiger-mode photodiode combined with a textured region and / or an isolation region configured to increase the absorption probability of incident photons. For example, the embodiments described herein can include optical structures (such as black silicon and / or diffractive light-trapping structures) in or on one or more surfaces of a pixel, the optical structures including one or more photodiodes. In some embodiments, the optical structure can be between the photodiode and the scene or field of view imaged thereby. The embodiments described herein can relate, for example, to preparing a rough surface using a laser, while the diffractive optical elements described herein provide a structure that may be about the wavelength or below the wavelength, which refracts light away from the surface of the sensor and away from the nearest photodiode, such that the optical path length of light in silicon is increased and thus the absorption probability is increased.

[0049] Designing a SPAD-based focal plane imaging array can involve conflicting design goals. On the one hand, it may be desirable to reduce the physical size of the SPAD device. The current flowing in the SPAD during avalanche and during its recharge is proportional to its capacitance, which in turn is proportional to its area. Also, smaller, lower-capacitance SPADs can provide shorter dead times, can detect photons more frequently, and can thus have a higher dynamic range than larger SPADs. Thus, to reduce the total current, power, and heat consumed by a single SPAD (or even more so, by a large SPAD array), and to provide a higher dynamic range, it may be desirable to reduce the area of the diode. Additionally, some noise sources in the SPAD (such as afterpulses) can be proportional to the SPAD area. On the other hand, for example, reducing the size of the SPAD typically results in a reduction in fill factor due to the guard ring structure that contains the avalanche and where detection cannot occur. Additionally, the resolution of some optical systems can be determined by their optics, and this resolution can be lower than the pitch of small SPADs. The collection efficiency of microlenses is also a function of their size, and specifically, can be limited in terms of their numerical aperture, and thus sometimes the collection efficiency of lower-pitch diodes can be improved.

[0050] Some embodiments of the present invention provide pixel arrays that maintain the benefits of small SPAD devices and also provide the advantages of lower-pitch arrays. Specifically, some embodiments can provide lower-power operation without sacrificing collection efficiency or effective fill factor, and can match the resolution of lower-cost optics with a reduced point spread function.

[0051] In addition, some embodiments of the present invention provide a photon-mixed optoelectronic structure for detecting photons with increased sensitivity in a pixel including two or more photodiodes. Without loss of generality, in some embodiments, each pixel includes more than one photodiode, but is positioned or otherwise configured to image or sample a region of the field of view of a two-dimensional optical sensor. Thus, when a photon enters the aperture region corresponding to the pixel, the photon has an equal probability of being absorbed in any one of the multiple photodiodes in the pixel. In some embodiments, each photodiode in the pixel is configured to generate a corresponding electrical signal to be processed by a corresponding electronic circuit element. In some embodiments, electrical signals from more than one photodiode in the pixel (e.g., via corresponding circuit elements) are compared, correlated, or subjected to a Boolean operation in order to generate the desired information. For example, a correlation between corresponding arrival times indicated by the corresponding electrical signals can be performed. In some embodiments, one or more photodiodes in the pixel can be globally or per-pixel (e.g., at a given time) statically or (e.g., in response to a change in the FoV and / or in response to a control signal (e.g., as provided by control circuit 605 as described herein)) dynamically disabled. The control signal can be generated in response to the signal level received by the pixel. For example, in response to an initial detection of a relatively strong signal from a target, three of the four SPADs defining the pixel can be deactivated, thereby reducing the power consumption of the pixel.

[0052] Figure 1A is a cross-sectional view showing a structure in the form of an optoelectronic device or a photodetector device according to some embodiments of the present invention. As Figure 1A shown, the photodetector device 100a includes a semiconductor material layer or sensor wafer 101 having one or more photodiodes 105 therein. For example, the semiconductor material layer 101 can include silicon (or other semiconductor) material having an incident light surface. First and second regions can be formed in the semiconductor material layer 101 (e.g., by doping) to define a semiconductor junction (e.g., a p-n junction) 105n / 105p of the photodiode 105. In some embodiments, the semiconductor material layer 101 can have a thickness ranging from about 1 μm to about 100 μm. The photodiode 105 can have a surface area ranging from about 0.1 μm2 to about 1000 μm 2 2. The photodetector device 100a can represent a part of an optical sensor array including a plurality of imaging pixels (e.g., a pixel structure, also referred to as a pixel).

[0053] The photodiode 105 can be a Geiger-mode photodiode, such as a single-photon avalanche detector (SPAD). The photodiode 105 is configured to be biased beyond its breakdown voltage to generate an electrical signal in response to detecting incident electromagnetic radiation (shown as incident photons 10). The electrical signal generated by the photodiode 105 is independent of the optical power of the incident photons 10. That is, the photodetector device 100a has a binary responsivity that is independent of the irradiance optical power of the electromagnetic radiation 10. In some embodiments, the photodiode 105 can be configured to detect electromagnetic radiation having at least one wavelength in the range from about 800 nanometers (nm) to about 1200 nm (e.g., by including a wavelength-selective filter in the path of the incident photons 10). The photodiode 105 also includes a guard-ring structure 105g for controlling the avalanche process and a textured region 115 coupled to the semiconductor material layer 101. The depicted (P-) guard ring 105g is for illustrative purposes only and can be replaced by many other guard rings known in the art without loss of generality.

[0054] The textured region 115 includes an optical structure that is positioned to interact with the incident photons 10 in the detection by the photodiode 105. For example, the textured region 115 can include a surface having a topological structure with surface variations on the nanoscale to the microscale. The characteristics of the textured region 115 can vary depending on the materials and techniques employed. In some embodiments, the textured region 115 can be a few hundred nanometers thick and composed of nanocrystals and nanopores (e.g., from about 10 nm to about 50 nm). In some embodiments, the textured region 115 can include microscale structures (e.g., from about 1 μm to about 60 μm). In some embodiments, the textured region 115a can include nanoscale structures and / or microscale structures from about 5 nm to about 10 μm.

[0055] In some embodiments, the textured region 115 can be formed in the surface of the semiconductor material layer 101. For example, the textured region 115 can be formed in a sensor wafer having the photodiode 105 therein or in the back surface or backside 101b of the semiconductor material layer 101 using one or more laser beams having sufficient energy to texture the surface of the semiconductor material layer 101. As another example, the back surface 101b of the semiconductor material layer 101 can be textured using a reactive chemical solution to form the textured region 115.

[0056] The texture region 115 is configured to increase the probability that one or more photodiodes 105 in the semiconductor material layer 101 absorb incident photons 10, specifically, by increasing the optical path length of the incident photons 10 in the semiconductor material layer 101. That is, for photons 10 incident on the surface 101b, the texture region 115 is configured to increase the path that the photons 10 travel within the wafer 101 before being detected by the photodiodes 105 (compared to the distance that the photons would travel directly from the surface 101b to the underlying photodiodes 105), where the longer optical path length can increase the absorption probability of the photons 10 and thus increase the sensitivity of the device 100a. For example, the absorption probability of long-wavelength photons (e.g., photons in the range of about 800 nm to about 1200 nm) that can be used by one or more emitters of a time-of-flight based measurement system can be increased. Although the texture region 115 is illustrated as being located between the photodiodes 105 and the electromagnetic radiation source 10, it will be understood that in some embodiments, the texture region 115 can be located on the side of the semiconductor material layer 101 opposite the source of the incident photons 10 (e.g., the photodiodes 105 are located between the texture region 115a and the source of the incident photons 10). More generally, the texture region 115 can be provided in one or more surfaces or regions of the semiconductor material layer 101 so as to interact with the detection of the incident photons 10 by one or more photodiodes 105 in the semiconductor material layer 101.

[0057] Still referring to Figure 1A , the photodetector device 100a can further include a first electrode 107n and a second electrode 107p. The electrodes 107n, 107p are configured to bias the photodiode 105 beyond its breakdown voltage based on the voltage difference between the electrodes 107n, 107p. Specifically, the electrodes 107n, 107p can be defined as the anode and cathode of the photodiode 105, and a reverse bias voltage can be applied across the electrodes 107n, 107p. In some embodiments, the reverse bias voltage can be from about 10 V to about 200 V. The voltage difference between the electrodes 107n, 107p defines an electric field gradient that pulls the charge generated in response to the detection of the incident photons 10 into the depletion region to create an avalanche condition in the photodiode 105. In some embodiments, the voltage difference between the electrodes 107n, 107p can be switched between a first voltage greater than the breakdown voltage of the photodiode 105 and a second voltage less than the breakdown voltage of the photodiode 105. In some embodiments, the electrodes 107n, 107p that define the anode and cathode of the photodiode 105 can be connected to a quenching circuit and / or a recharging circuit.

[0058] In some embodiments, the backside electrode 107b may be disposed on or around the texture region 115. In some embodiments, an additional electrode 107e may be disposed adjacent to and / or extending along the isolation region 110. The electrodes 107b, 107e may be configured to confine the photo-generated charges to the pixel region to reduce crosstalk. The isolation region (shown as an example as a deep trench isolation (DTI) structure or region 110) may be filled with a dielectric material (such as SiO 2 ) and passivated, for example, with a highly doped semiconductor material to avoid forming defects in the semiconductor material layer 101. In some embodiments, the semiconductor material layer 101 may be a crystalline silicon substrate.

[0059] The photodiode 105 may include a guard ring structure 105g for more uniform avalanche breakdown. In some embodiments, the photodiode 105 may include a substantially planar semiconductor junction 105n / 105p and a guard ring structure 105g at or along the periphery of the junction 105n / 105p such that the electric field formed when the junction 105n / 105p is reverse-biased is sufficiently uniform. Thus, at avalanche breakdown, most of the avalanche current may flow within the planar region of the junction 105n / 105p rather than at the edge or corner of the junction 105n / 105p. Although the present disclosure has been mainly described with reference to a diffused P-type guard ring 105g around the p-n junction 105n / 105p formed in a P-type substrate 105p as the semiconductor material layer 101, it should be understood that embodiments of the present invention may include photodetector devices of the opposite conduction type (e.g., an N-type substrate as the semiconductor material layer, where a diffused n-type guard ring surrounds the p-n junction) and / or other photodiode types.

[0060] Figure 1B and Figure 1C are cross-sectional views showing photodetector devices 100b, 100c according to some embodiments of the present invention. As Figure 1B and Figure 1CAs shown, the photodetector devices 100b, 100c include an arrangement of a semiconductor material layer or sensor wafer 101, which includes a single Geiger-mode photodiode 105 having a guard ring structure 105g. The photodiode 105 is separated from other Geiger-mode photodiodes in the semiconductor material layer 101 by isolation regions (shown as an example as deep trench isolation (DTI) structures or regions 110). The isolation regions can define a barrier formed between adjacent photodiodes 105, thereby providing the boundary of the corresponding pixel structure. Without loss of generality, the barrier can be in the form of a trench, a passivated trench, a filled trench, a filled passivated trench, an electric field defined by electrodes on the front surface of the wafer (e.g., a silicon material wafer), an electric field defined by electrodes on the back surface of the wafer, an electric field defined by electrodes on or in the trench, and an electric field defined by charged silicon vias.

[0061] In Figure 1B and Figure 1C , the isolation region in the form of the DTI region 110 surrounds the photodiode 105 in the sensor wafer 101. The DTI region 110 defines the boundary of the pixel defined by the photodiode 105. In Figure 1B , the electrode 107e extends along the DTI region 110 on the opposite side of the photodiode 105. In Figure 1C , the backside electrode 107b also extends along the DTI region 110 and along the optical structure 115' above the photodiode 105. The electrodes 107n, 107p, 107b, 107e can be formed of a material (such as indium tin oxide (ITO)) that is substantially transparent to photons 10 in the wavelength range corresponding to the optical signal to be detected. In some embodiments, such transparent electrodes 107n, 107p, 107b, 107e can extend across most or all of the optical structure 115'. In some embodiments, due to the relatively high electric field that may exist in the Geiger-mode photodiode 105, passivation can be applied to the DTI region 110 so that discontinuities in the crystal structure of the semiconductor material layer (e.g., silicon) 101 do not inject charge into the high electric field region, resulting in a high dark count rate.

[0062] The textured region including the optical structure 115' is positioned on the light-receiving surface of the photodetector devices 100b, 100c between the photodiode 105 and the source of incident photons 10 to interact with the photodiode 105 in the semiconductor material layer 101 and increase the probability that the incident photons 10 are absorbed by the photodiode 105 in the semiconductor material layer 101. As discussed above with reference to Figure 1A Similarly, the optical structure 115' is configured to specifically increase the probability that the photodiode 105 absorbs the incident photons 10 by increasing the optical path length of the incident photons 10 in the semiconductor material layer 101. InFigure 1B and Figure 1C In Figure 1B and Figure 1C , the optical structure 115’ is a diffractive element, which is shown as an inverted pyramid array (IPA) structure protruding from the backside 101b of the sensor wafer 101 towards the photodiode 105. The diffractive elements 115’ may each include one or more dimensions that are less than the wavelength of the incident photons 20. In some embodiments, the diffractive elements 115’ may be configured to refract the incident photons 10 at an angle such that the incident photons 10 undergo total internal reflection from the respective isolation regions 110.

[0063] As Figure 1A 、 Figure 1B and Figure 1C shown, the sensor wafer 101 may be bonded to or otherwise stacked on the surface of the readout wafer 102. The readout wafer 102 includes metallization 108 and electronic circuit elements coupled to the photodiodes 105 to provide a processing path 199 for an electrical signal (also referred to herein as a detection signal) generated by the photodiodes 105 in response to the incident photons 10. In some embodiments, the electronic circuit elements of the readout wafer 102 may include an active quenching circuit and / or a passive quenching circuit and / or a recharge circuit for each photodiode 105, such as those described in U.S. Patent Application No. 2019 / 0250257, entitled “Methods and Systems for High-Resolution Long Range Flash Lidar”, the disclosure of which is incorporated herein by reference. The readout wafer 102 may also include a controller, a timing circuit, and / or associated circuits configured to perform ToF measurement operations as described herein (e.g., as discussed with reference to Figure 6A and Figure 6B ).

[0064] ​​​​Further embodiments of the present invention are directed to photodetector devices and optical sensor arrays, where isolation regions extend between or surround photodiodes. These multiple photodiodes can be activated together, or only partially activated, such that a subset of the photodiodes is activated. For example, in response to detecting a relatively strong signal from a target, only one of the four SPADs defining a pixel can be activated, thereby reducing the power consumption of the pixel by 75%. These multiple photodiodes can be read individually, i.e., their outputs can be sampled using corresponding electronics and / or circuit paths that are not shared by some or all of the other photodiodes between the isolation regions. A group or set of photodiodes between the isolation regions can define a pixel that is a single element that produces an image, where the image can refer to the collective output of the pixel array and can include any output, such as photon flux, photon polarization, photon arrival time, etc. Thus, photons incident on an optical structure (e.g., an IPA) anywhere on, in, or above the pixel structure can be absorbed by any of the photodiodes anywhere within the pixel volume, and the generated charge can be collected and output by any of the photodiodes in the pixel to "mix" the incident photons spatially in order to sample the field of view being imaged more uniformly. That is, two or more photodiodes and / or diffractive optical elements of each pixel are configured to distribute the incident flux across multiple photodiodes, which can reduce or avoid saturation in any of the photodiodes of the pixel, thereby increasing the dynamic range.

[0065] In contrast, when using some conventional optical devices, the probability of absorption is typically non-uniform and typically increases or maximizes in a single spot in the pixel. Conventional optical devices are such as macrolenses outside the die and microlenses on top of the wafer (i.e., optical devices without diffractive optical structures). This can be undesirable in the case of pixels having multiple photodiodes (such as in correlation detection pixels) because the absorption probability across the photodiodes may not be balanced. If one microlens is used per photodiodes, the volume that each photodiodes is sensing may not exactly overlap with the volume that the associated photodiodes is sensing, and thus the true correlation of the arrival of photons from an object may not be achieved. Additionally, some conventional devices using an IPA structure can include DTI regions between the photodiodes that are reverse-biased at a voltage lower than the breakdown voltage of the junction in order to limit the absorption of reflected photons in adjacent photodiodes. These DTI regions typically extend all the way from the surface of the silicon to the backside, such that any photo-generated charge will typically diffuse and be collected only by the photodiodes below their absorption regions.

[0066] Figure 2A and Figure 2Bis a cross-sectional view showing an example photodetector device including a plurality of photodiodes between isolation regions according to some embodiments of the present invention, wherein each of the photodiodes provides a corresponding electrical output for readout via a corresponding electronic circuit. As Figure 2A and Figure 2B shown, the photodetector devices 200a, 200b include a semiconductor material layer or sensor wafer 201 having two or more photodiodes 105a, 105b therein. Each of the photodiodes 105a, 105b may include a first region and a second region defining a semiconductor junction (e.g., a p-n junction) 105n / 105p. The photodiodes 105a, 105b include a guard ring structure 105g for more uniform avalanche breakdown, wherein each of the photodiodes may include a substantially planar semiconductor junction 105n / 105p, and the guard ring structure 105g is located at the edge of the junction 105n / 105p or along the periphery of the junction 105n / 105p. In Figure 2A - the example of FIG. 2C, a common guard ring structure 105g extends around the plurality of photodiodes 105a, 105b, but embodiments of the present invention are not limited thereto, and in some embodiments, each of the photodiodes 105a and 105b may include a corresponding guard ring 105g. The photodiodes 105a, 105b may be Geiger-mode photodiodes (such as SPADs), each configured to be biased beyond its breakdown voltage to generate an electrical signal in response to detecting an incident photon 10. The photodetector devices 200a, 200b may each represent a part (e.g., a pixel) of an optical sensor array including a plurality of imaging pixels, wherein two or more photodiodes 105a, 105b define each pixel.

[0067] Figure 2A and Figure 2B The photodetector devices 200a, 200b further include isolation regions separating the two or more photodiodes 105a, 105b defining a pixel from adjacent pixels of the photodetector device. In Figure 2A and Figure 2BIn the example, the isolation region is shown as the DTI region 110, but it should be understood that embodiments of the present invention may include other barriers as the isolation region between adjacent pixels. In some embodiments, the DTI region 110 extends from the surface adjacent to the photodiodes 105a, 105b to the surface of the semiconductor material layer 201 (shown as the back side 201b), thereby providing substantially and / or complete isolation between adjacent pixels. There is no corresponding DTI region 110 between two or more photodiodes 105a, 105b of each pixel, so incident photons 10 can be detected by any one of the multiple photodiodes 105a, 105b in each pixel. For example, the photodiodes 105a, 105b can be implemented by corresponding SPADs, where each pixel defines a composite SPAD structure (e.g., a quaternary SPAD array in each pixel, only two of the SPADs 105a and 105b are shown in the cross-section of Figure 2A - FIG. 2C). This arrangement provides multiple photodiodes 105, 105b that sample the same angular region of the field of view, where each of the photodiodes 105a, 105b samples a corresponding angular sub-part of the angular region without being isolated from the others among the photodiodes 105a, 105b.

[0068] The photodetector devices 200a, 200b may further include optical structures 115, 115', which are configured to direct the incident photons 10 to any one of the two or more photodiodes 105a, 105b in each pixel, rather than to a specific photodiode. For example, the optical structures 115, 115' are positioned between the photodiodes 105a, 105b and the source of the incident photons 10. In Figure 2A this case, the textured region (e.g., the textured surface of the semiconductor material layer of the sensor wafer 201) provides the optical structure 115, while in Figure 2B this case, the optical structure 115' is implemented as an array of diffraction elements (shown as an IPA structure protruding towards two or more photodiodes 105a, 105b of each pixel).

[0069] In some embodiments, the optical structures 115, 115' may have various sizes and shapes as described herein and may include corresponding elements having one or more dimensions less than the wavelength of the incident photons 10 (e.g., the pyramidal structures of the corresponding IPAs). For example, the diffractive element 115' may be configured to refract the incident photons 10 at an angle such that the incident photons 10 undergo total internal reflection from the corresponding isolation region 110. The optical structures 115, 115' are configured to increase the path that the photons 10 travel within the volume of the pixel (compared to the distance that the photons would travel directly from the surface 201b to the underlying photodiode 105a or 105b) before being detected by one of the photodiodes 105a or 105b of the pixel. For example, by guiding the photons 10 away from the nearer one of the photodiodes 105a and towards the farther one of the photodiodes 105b. More generally, the optical structures 115, 115' are configured to increase the optical path length of the incident photons 10 in the photodetector devices 200a, 200b (and thus increase the probability of absorption or detection of the incident photons 10 in the photodetector devices 200a, 200b) relative to the distance that the incident light perpendicular to the surface (e.g., the backside 201b) would travel to reach directly below the photodiodes 105a or 105b of the photodetector devices 200a, 200b (e.g., a distance corresponding to the thickness of the wafer 201).

[0070] The arrangement of the groups of the plurality of photodiodes 105a, 105b in each pixel and / or the arrangement of the optical structures 115, 115' that define the isolation region 110 for guiding the incident photons 10 to any one of the plurality of photodiodes 105a in each pixel may provide a photon mixing structure for more uniform imaging (also referred to herein as sampling) of the field of view. For example, as Figure 2A and Figure 2B shown by the arrows in, the isolation region 110 and / or the optical structures 115, 115' are configured to increase the optical path length of the photons 10 incident on the left and right photodiodes 105a and 105b and spatially mix the photons 10 incident on the left and right photodiodes 105a and 105b, for example, by guiding the photons 10 to reflect from the isolation region 110 within each pixel and / or other reflective surfaces between the isolation regions 110. Specifically, as Figure 2A and Figure 2B shown by the arrows in, the photons 10 incident on the backside 201b above the left photodiode 105a may be redirected away from the nearest photodiode 105a by the optical structures 115, 115' and reflected multiple times from the opposite surface of the sensor wafer 201 and / or the surface of the guard ring 105g before being absorbed by the right photodiode 105b.

[0071] The photodiodes 105a and 105b are each oriented to sample a respective sub - portion of the field of view of the pixel (e.g., a respective sub - portion of the 1° field of view of the pixel). In other words, each of the photodiodes 105a, 105b is positioned to sample a respective angular sub - region of the angular region imaged by the pixel, and the photon - mixing structure defined by the isolation regions 110 and / or the optical structures 115, 115' is configured to distribute the incident flux 10 over multiple photodiodes 105a, 105b of each pixel at the expense of spatial resolution to provide a more uniform sampling of the angular region imaged by the pixel. Thus, the photodetector devices 200a, 200b are configured to generate respective electrical signals in response to incident photons 10 detected by any one of two or more photodiodes 105a, 105b in each pixel, and the photon - mixing structure can avoid (or reduce the likelihood of) saturation of any of the photodiodes 105a, 105b, thereby increasing the dynamic range of the photodetector devices 200a, 200b.

[0072] Still referring to Figure 2A and Figure 2B , the photodetector devices 200a, 200b can include a first electrode and a second electrode 107n, 107p, which are configured to bias each of the photodiodes 105a, 105b beyond its respective breakdown voltage based on the voltage difference between the electrodes. The electrodes 107n, 107p can define the respective anodes and cathodes of each of the photodiodes 105a, 105b in the pixel, such that different subsets or subgroups of the photodiodes 105a, 105b in each pixel can be individually activated or deactivated for detecting incident photons. In some embodiments, the voltage difference between the electrodes 107n, 107p can be switched between a first voltage greater than the respective breakdown voltage to activate the respective photodiodes 105a and / or 105b and a second voltage less than the respective breakdown voltage to deactivate the respective photodiodes 105a and / or 105b. For example, in response to incident photons detected by multiple photodiodes 105a and 105b of a pixel, a subset of the photodiodes 105a and 105b can be deactivated to reduce power consumption.

[0073] Each of the photodiodes 105a, 105b of the pixel can be configured to output a respective electrical signal readout A, readout B to a respective processing path (e.g., as provided by a readout circuit) in response to detecting incident photons 10. The readout circuit can be provided on the sensor wafer 201 or on a different substrate (e.g., on the readout wafers 202, 302, 402, 502 as described herein). The respective processing paths can include respective electronic circuit elements not shared by two or more photodiodes 105a, 105b of each pixel.

[0074] In some embodiments, the readout circuit may include a correlator or controller circuit configured to distinguish incident photons corresponding to an optical signal output from a time-of-flight measurement system (e.g., a lidar transmitter array) from ambient light based on the respective arrival times of two or more photons relative to each other within a predetermined correlation time. Such correlator circuits are described, for example, in U.S. Patent Application No. 2019 / 0250257, entitled "Methods and Systems for High-Resolution Long Range Flash Lidar", the disclosure of which is incorporated herein by reference. The respective electrical signals Readout A and Readout B generated by the photodiodes 105a, 105b may be output via respective transmission paths to a readout circuit (e.g., as provided in readout wafers 202, 302, 402, 502). The readout circuit may be configured to perform temporal and / or spectral correlation between the respective electrical signals Readout A and Readout B in response to incident photons 10 based on the relative arrival times (temporal correlation) and / or respective wavelengths (spectral correlation) of the photons 10.

[0075] For example, when operating a LIDAR system under ambient light conditions, it may be difficult for a SPAD-based photodetector device or an array of optical sensors to distinguish photons from ambient light (also referred to as background photons) from photons of an optical signal output from one or more lidar transmitters (also referred to as signal photons). The readout circuit may include a correlator and a photon counter or a time integrator having respective inputs for the electrical signals Readout A and Readout B generated by the photodiodes 105a and 105b in response to detecting incident photons 10, respectively. The photon counter or time integrator may be configured to selectively count photons based on the temporal correlation (also referred to as coincidence or correlation detection) between the respective arrival times of the photons, which may reduce the amount of incident photons to be processed. For example, based on the recognition that photons originating from a pulsed LIDAR transmitter (e.g., a laser) and reflected by a target may arrive within a relatively narrow time window or correlation window, the readout circuit may selectively utilize some of the electrical signals Readout A and Readout B received within the correlation window in the ToF measurement calculation while rejecting or discarding others of the electrical signals Readout A and Readout B that fall outside the correlation window due to uncorrelated photons originating from an ambient light source (e.g., the sun). Such temporal correlation operations may increase the signal-to-background ratio of the photodetector devices 200a, 200b under high ambient light conditions.

[0076] In some embodiments, a Shallow Trench Isolation (SrTI) structure may be provided between two or more photodiodes 105a, 105b in each pixel. Figure 3 An example structure of multiple photodiodes between DTI regions is shown, where an SrTI structure is provided between adjacent photodiodes in a pixel.

[0077] Figure 3 FIG. is a cross-sectional view of an example photodetector device including an SrTI structure between multiple photodiodes in each pixel according to some embodiments of the present invention, wherein each of the photodiodes provides a corresponding electrical output for readout via a corresponding electronic circuit. As Figure 3 shown, the photodetector device 300 includes a semiconductor layer or sensor wafer 301. The sensor wafer 301 may include elements similar to or corresponding to the sensor wafer 201 of FIG. 2. The sensor wafer 301 includes: two or more photodiodes 105a, 105b, an isolation region 110, and an optical structure 115'. The two or more photodiodes 105a, 105b define one pixel among a plurality of pixels. The isolation region 110 separates the photodiodes 105a, 105b from adjacent pixels. The optical structure 115' is configured to direct incident photons 10 to any one of the two or more photodiodes 105a, 105b in each pixel, rather than a specific photodiode. The sensor wafer 301 further includes a Shallow Trench Isolation (SrTI) structure 311 formed between the two photodiodes 105a, 105b of the pixel. The SrTI structure 311 is shallower than the DTI region 110 at the boundary of each pixel. That is, the corresponding DTI region 110 protrudes away from the photodiodes 105a, 105b towards the light receiving surface (shown as the back side 301b in the figure) and exceeds the SrTI structure 311 (i.e., is higher than the SrTI structure 311 or taller than the SrTI structure 311).

[0078] In Figure 3 the example of, each of the photodiodes 105a and 105b includes a corresponding guard ring structure 105g, wherein the SrTI structure 311 is located between the corresponding guard ring structures 105g. The SrTI structure 311 has a height or depth sufficient to allow an increased optical path length of the incident photons 10 (shown by the solid arrow in Figure 3 within the pixel defined by the photodetector device 300), but the height or depth is sufficient to reduce the one of the photodiodes 105a, 105b ( Figure 3The absorption probability of secondary photons generated by hot electrons (shown by the dashed arrows) cannot reach the regions above other photodiodes in the photodiodes 105a and 105b. For example, when an avalanche flows through the junction 105n / 105p of the first photodiode 105a, hot electrons can recombine, resulting in the re-emission of secondary "hot electron" photons during this process. These hot electron photons may induce secondary related avalanches in the neighboring photodiode(s) 105b of the pixel, which may be undesirable. Thus, the SrTI structure 311 is shallower than the DTI region 110 to allow the signal photons 10 to be distributed across multiple photodiodes 105a and 105b in the pixel, but the SrTI structure 311 is deep enough to reduce the probability of secondary photons generated by hot electrons reaching the regions above neighboring or adjacent photodiodes 105a or 105b between the same DTI regions 110, thereby reducing the probability of optical crosstalk between the photodiodes 105a and 105b in the pixel.

[0079] In some embodiments, the SrTI structure 311 may protrude away from the junction 105n / 105p towards the light receiving surface (shown as the back side 301b) and extend beyond the respective guard ring structures 105g of the photodiodes 105a and 105b, and the DTI region 110 may protrude beyond the SrTI structure 311. That is, the SrTI structure 311 is higher than the guard ring structure 105g or taller than the guard ring structure 105g, and the DTI region 110 is higher than the SrTI structure 311 or taller than the SrTI structure 311. The SrTI structure 311 may be formed of an insulating material having a breakdown strength greater than that of the material of the sensor wafer 301, allowing the photodiodes 105a and 105b to be placed closer laterally, with less electric field interference between the photodiodes 105a and 105b. For example, the sensor wafer 301 may be silicon (Si)-based, and the SrTI structure 311 may be silicon dioxide (SiO 2 )), and the breakdown strength of silicon dioxide (SiO 2 ) is approximately 10 times that of Si. In some embodiments, the SrTI structure 311 may be formed of the same or similar material as the DTI region 110.

[0080] Figure 4 is a cross-sectional view showing an example photodetector device according to some embodiments of the present invention. As Figure 4 shown, the photodetector device 400 includes a stacked structure having a sensor wafer 401 on a readout wafer 402. The sensor wafer 401 may include Figure 3Elements similar or corresponding to the sensor wafer 301, the sensor wafer 401 includes: two or more photodiodes 105a, 105b, an isolation region 110, an optical structure 115', and an SrTI structure 311. The two or more photodiodes 105a, 105b define one pixel among a plurality of pixels. The isolation region 110 separates the photodiodes 105a, 105b from adjacent pixels. The optical structure 115' is configured to direct incident photons 10 to any one of the two or more photodiodes 105a, 105b in each pixel, rather than a specific photodiode. The SrTI structure 311 is between the two photodiodes 105a, 105b of the pixel.

[0081] In the photodetector device 400, the sensor wafer 401 is bonded to the surface of the readout wafer 402. The readout wafer 402 includes corresponding electrical signal output readouts A and B for the photodiodes 105a, 105b, and corresponding electrical processing paths 499a, 499b. The corresponding processing paths 499a, 499b of the readout wafer 402 may include corresponding electronic circuit elements not shared by the photodiodes 105a, 105b of the pixel. In particular, the processing path 499a may provide the electrical signal readout A output from the photodiode 105a to a transistor (shown as MOSFET A) of the underlying readout wafer 402, while the processing path 499b may separately provide the electrical signal readout B output from the photodiode 105b to a transistor (shown as MOSFET B) of the underlying readout wafer 402. As described above, the corresponding processing paths 499a, 499b of the readout wafer 402 may include additional circuit elements not shared by the photodiodes 105a, 105b of the same pixel, such as an active quenching circuit and / or a passive quenching circuit and / or a recharge circuit. The readout wafer 402 may also include circuit elements that may be shared by the photodiodes 105a, 105b of the pixel, such as a controller, timing, and / or related circuits configured to perform ToF measurement operations as described herein.

[0082] In some embodiments, one or more metal layers or structures are positioned adjacent to the surface of the readout wafer that provides an interface with the sensor wafer. Figure 5 is a cross-sectional view showing an example photodetector device according to some embodiments of the present invention. As Figure 5 shown, the photodetector device 500 includes a stacked structure having a sensor wafer 501 on a readout wafer 502. The sensor wafer 501 may include Figure 4For a sensor wafer 401 with similar or corresponding components, the sensor wafer 501 includes: two or more photodiodes 105a, 105b, an isolation region 110, an optical structure 115’, and an SrTI structure 311. The two or more photodiodes 105a, 105b define one pixel among a plurality of pixels. The isolation region 110 separates the photodiodes 105a, 105b from adjacent pixels. The optical structure 115’ is configured to direct incident photons 10 to any one of the two or more photodiodes 105a, 105b in each pixel, rather than a specific photodiode, and to direct the incident photons 10 to the SrTI structure 311 between the two photodiodes 105a, 105b of the pixel.

[0083] In the photodetector device 500, the sensor wafer 501 is bonded to the surface of the readout wafer 502. The readout wafer 502 includes metal layers 508a, 508b adjacent to the surface of the readout wafer 502 at the interface with the sensor wafer 501. As can be seen in the exemplary structure 500 shown in Figure 5 the pixel region or “cube” formed by the optical structure 115’ and the DTI region 110 is open or relatively unobstructed on the front side 501f of the photodetector device 500. Metal layers 508a, 508b are provided between the photodiodes 105a, 105b and the front side 501f such that the pixel region is substantially optically sealed. The metal layers 508a, 508b may be configured to provide an electrical signal to the photodiodes 105a, 105b or to provide an electrical signal from the photodiodes 105a, 105b (e.g., to bias the devices 105a, 105b or for carrying signals output from the photodiodes 105a, 105b).

[0084] The metal layers 508a, 508b may be configured to perform multiple functions or serve multiple purposes. Electrically, the metal layers 508a, 508b can be used as capacitors to store charge near the photodiodes 105a, 105b. For example, the photodiodes 105a, 105b can be SPADs, which (in ToF applications) may have timing requirements on the order of nanoseconds (ns) or picoseconds (ps). Since capacitance can affect the recharge time, dark count rate, and / or afterpulse of the photodiodes 105a, 105b, providing the metal layers 508a, 508b adjacent to the interface with the sensor wafer 501 (and thus in close proximity to the corresponding photodiodes 105a, 105b) can provide a relatively low inductance between the charge storage nodes defined by the junctions 105n / 105p of the metal layers 508a, 508b and the photodiodes 105a, 105b, such that the capacitors 508a, 508b can be charged and discharged more quickly.

[0085] Additionally or alternatively, the metal layers 508a, 508b can be configured to act as capacitors that are part of an analog time integrator or an analog counter for the associated SPAD pixels. For example, the readout wafer 502 can include corresponding electronic circuit elements that define an analog time integrator or an analog counter, and the metal layers 508a, 508b can define the capacitors for the analog time integrator or analog counter to integrate or count.

[0086] Additionally or alternatively, the metal layers 508a, 508b can include one or more surfaces that are configured to increase the optical path length of incident photons, i.e., reflect the light back into the pixel region (as shown by the solid arrows in Figure 5 ), and thus further increase the detection probability. That is, the metal layers 508a, 508b can include reflective surfaces that extend beneath the photodiodes 105a, 105b and that are configured to provide corresponding charge storage nodes for reflecting light into the pixels. In some embodiments, the metal layers 508a, 508b can be implemented as a metal-insulator-metal (MiM) structure or a metal-oxide-metal (MoM) structure.

[0087] In some embodiments, the pitch of the isolation regions 110 that define each pixel can be different in different directions (e.g., horizontal and vertical) along the light receiving surface of the photodetector devices 100a, 100b, 100c, 200a, 200b, 300, 400, 500 or the optical sensor array defined thereby. For example, the vertical pitch of the isolation regions 110 can be different from the horizontal pitch of the isolation regions 110. This can provide a pixel structure that is asymmetric across axes (e.g., in different directions along the light receiving surface of the optical sensor array, such as along the X-axis and the Y-axis), thereby diffusing photons across the pixel structure (in some cases, approximately uniformly) without using optical elements such as aspherical lenses.

[0088] In some embodiments, the pixel structure of the photodetector devices 100b, 100c, 200b, 300, 400, 500 can further include a texture region 115 that is positioned to interact with the incident electromagnetic radiation 10 in combination with the diffraction element 115'. For example, the texture region 115 can be provided as a layer or region of black silicon that is positioned adjacent to the front side of the photodetector devices 100b, 100c, 200b, 300, 400, 500 and opposite to the back sides 101b, 201b, 301b, 401b, 501b that include the diffraction element 115' thereon. The black silicon region can be configured to reduce reflectivity and increase the wavelength range of light absorbed by the photodiodes of each pixel.

[0089] More generally, embodiments described herein may use optical structures (including IPAs or other diffractive structures) to equalize detection across multiple photodiodes included in a pixel, where DTI regions (or other isolation structures) separate the groups of photodiodes that define each pixel. The DTI regions and the IPA are arranged or otherwise configured to create a "photon mixer" that sends photons to the various photodiodes in the pixel defined between adjacent DTI regions, regardless of where the photons originate in the field of view.

[0090] Embodiments of the present invention may be used in optical sensor arrays, such as detector arrays in ToF-based imaging applications. For example, flash LIDAR may use a pulsed light emission array to emit light over a relatively large area in a short period of time to acquire an image based on sensing of the reflected light emission, thereby providing solid-state imaging with a large field of view. Non-flash or scanning LIDAR systems may generate an image frame by scanning the light emission over the field of view or scene (e.g., using point scanning or line scanning (e.g., emitted from a one-dimensional (1D) emitter array), emitting the required power for each point and scanning sequentially to reconstruct the full FoV). Non-range-gated LIDAR systems may illuminate the entire range of interest and collect echoes from the entire range of interest. Indirect time-of-flight (iToF) LIDAR systems may measure range by detecting the phase shift of the echo with respect to the emitted signal, while direct time-of-flight (dToF) lidar measures range by detecting the time from the emission of a light pulse to the detection of the light pulse by the receiver. In a specific application, a detector array using Geiger-mode single-photon detectors (such as a SPAD detector array) may be used to perform the sensing of the reflected light by the photodetector device. The SPAD detector array may be used as a solid-state detector in imaging applications where high sensitivity and timing resolution are desired.

[0091] Figure 6A and Figure 6B Examples of time-of-flight measurement systems 600a and 600b and related components in a lidar application in accordance with some embodiments of the present invention are shown. As Figure 6AAs shown, the lidar ToF circuit or system 600a may include a controller or control circuit 605, a timing generator or driver circuit 616, and an array 610 of detector elements; the timing generator or driver circuit 616 controls the timing and amplitude of an illumination source (shown as an array 615 of emitter elements), and the array 610 of detector elements (shown, for example, as a SPAD array) is configured to generate an electrical signal independent of the optical power of incident photons. The emitter array 615 emits radiation pulses as optical signals 630 at times controlled by the controller 605 and / or the driver circuit 616. Radiation in the form of a reflected optical signal (echo signal) 635 is reflected from the target 650 and detected or sensed by the SPAD array 610, e.g., incident photons 10 as described herein. The controller 605 implements a pixel processor that uses direct or indirect ToF measurement techniques to measure the time of flight of the illumination pulses 630, 635 on their journey from the emitter array 615 to the target 650 and back to the detector array 610.

[0092] Figure 6B More particularly shown is a lidar ToF circuit or system 600b according to some embodiments of the present invention. System 600b includes a control circuit 605, a timing circuit 606, an illumination source (illustrated as an emitter array 615 including a plurality of emitters 615e), and a detector array 610 including a plurality of detector pixels 610d. One or more of the emitter elements 615e of the emitter array 615 may define an emitter unit that emits radiation pulses or continuous wave signals, respectively, at times and repetition rates controlled by the timing generator or driver circuit 616 (e.g., through a diffuser or optical filter 614). In a particular embodiment, the emitter 615e may be a pulsed light source, such as an LED or a laser (such as a vertical cavity surface emitting laser (VCSEL) and / or an edge emitting laser).

[0093] In some embodiments, the emitter module or circuit can include an array 615 of emitter elements 615e, a corresponding array of optical elements 613, 614 (e.g., one or more lenses 613 (such as microlenses) and / or diffusers 614) coupled to one or more of the emitter elements, and a driver circuit 616. In some embodiments, each emitter element 615e in the emitter array 615 is connected to a corresponding driver circuit 616 and is controlled by the corresponding driver circuit 616. In other embodiments, groups of emitter elements 615e in the emitter array 615 (e.g., emitter elements 615e that are spatially close to each other) can be connected to the same driver circuit 616. The driver circuit 616 can include one or more driver transistors configured to control the pulse repetition rate, timing, and amplitude of the optical emission signals output from the emitters 615e.

[0094] In some embodiments, the detector module or circuit includes an array 610 of detector pixels 610d, receiver optics 612 (e.g., one or more lenses that collect light over the FoV 690 of the array 610), and receiver electronics (including timing circuit 606) configured to power, enable, and disable all or part of the detector array 610 and to provide timing signals to the detector array 610. The receiver optics 612 can include a macro lens, a spectral filter 611, microlenses, and / or an anti-reflection coating. The macro lens is configured to collect light from the maximum FoV that can be imaged by the lidar system; the spectral filter 611 passes or allows a portion of the 'signal' light that is high enough (i.e., light having wavelengths corresponding to those of the optical signal output from the emitter) to pass through, but substantially rejects or prevents non-signal or 'background' light (i.e., light having wavelengths different from those of the optical signal output from the emitter) from passing through; the microlenses are used to improve the collection efficiency of the detection pixels; and the anti-reflection coating is used to reduce or prevent the detection of stray light.

[0095] Detector pixel 610d includes a time-of-flight sensor (e.g., a single-photon detector array such as a Geiger-mode avalanche diode (e.g., SPAD)). Detector array 610 can include any one of the photodetector devices 100a - 100c, 200a - 200b, 300, 400, 500 described herein, where each detector pixel 610d includes one or more of the photodiodes 105, 105a, 105b described herein, and one or more of the photodiodes 105, 105a, 105b are configured to generate an electrical signal independent of the optical power of the incident photons. That is, detector array 610 can include any combination of pixel structures represented by the photodetector devices 100a - 100c, 200a - 200b, 300, 400, 500 described herein.

[0096] Timing circuit 606 can control the timing and gain / sensitivity of detector array 610. In some embodiments, the timing circuit 606 of detector array 610 can be phase-locked to the driver circuit 616 of transmitter array 615. Timing circuit 606 can also control the sensitivity of each detector pixel 610d, a group of detector pixels, or the respective photodiodes of each detector pixel 610d. For example, when detector pixel 610d includes a reverse-biased Geiger-mode photodiode, the reverse bias applied to each photodiode can be adjusted (e.g., based on the voltage difference of the electrodes 107n, 107p described herein), whereby the higher the overbias, the higher the sensitivity. Detector pixel 610d can be activated or deactivated with at least nanosecond precision, and the photodiodes of detector pixel 610d can be individually addressable, group-addressable, and / or globally addressable.

[0097] As Figure 6B shown, the light emission output from one or more transmitters in transmitter 615e irradiates one or more targets 650 and is reflected by one or more targets 650, and the reflected light is detected as an echo signal by one or more detector pixels in detector pixel 610d. The reflected light is converted into an electrical signal representation (referred to herein as a detection signal), and the reflected light (e.g., based on the time of flight) is processed to define a 3D point cloud representation 670 of the scene within the field of view 690. The operation of the LIDAR system according to embodiments of the present invention described herein can be performed by one or more processors or controllers (such as Figure 6A and Figure 6B control circuit 605).

[0098] Embodiments of the invention described herein provide Geiger mode avalanche diodes with high quantum efficiency and optical sensor arrays thereof. Additionally, embodiments of the invention relate to photon mixing image sensor pixels with enhanced sensitivity, which include multiple photodiodes in the same pixel to sample the field of view of the pixel more uniformly. The 'fill factor' of the sensor array can be increased by reducing or omitting the isolation regions (e.g., DTI regions) between the photodiodes, which otherwise can occupy the surface of the pixel array and reduce the available pixel area. Texture regions and / or other optical structures described herein may be positioned in or on the optical sensor array to direct incident photons to any one of the multiple photodiodes in the pixel. Some embodiments may sacrifice spatial resolution by using a composite pixel structure having multiple photodiodes per pixel that sample the same angular space between isolation regions. Embodiments of the invention include, but are not limited to, the following.

[0099] For example, in some embodiments, an optoelectronic device may include a Geiger mode avalanche photodiode, which may include a semiconductor material (e.g., silicon) having an incident light surface, a first region and a second region (e.g., doped regions) forming a semiconductor junction (e.g., p-n junction) in the semiconductor material, a guard ring structure for controlling the avalanche process, and a texture region coupled to the semiconductor material and positioned to interact with electromagnetic radiation. The optoelectronic device has a binary responsivity independent of the irradiating light power, e.g., having electromagnetic radiation at at least one wavelength in the range from about 800 nanometers (nm) to about 1200 nm.

[0100] In some embodiments, the texture region is positioned on the same side of the silicon (or other semiconductor) material as the incident light surface. In some embodiments, the texture region is positioned on the side of the silicon (or other semiconductor) material opposite to the incident light surface.

[0101] In some embodiments, the silicon (or other semiconductor) material may have a thickness from about 1 micrometer (μm) to about 100 μm. In some embodiments, the semiconductor junction may have a surface area from about 0.1 μm 2 to about 1000 μm 2 .

[0102] In some embodiments, the optoelectronic device may be surrounded by a structure (e.g., guard ring structure) such that the electric field formed when the junction is reverse-biased is sufficiently uniform. Thus, at avalanche breakdown, most or substantially all of the avalanche current may flow in the planar region of the junction rather than at the edges or corners of the junction.

[0103] In some embodiments, the optoelectronic device may include a first contact and a second contact. The first contact and the second contact may define an anode contact and a cathode contact of a photodiode. The voltage difference between the first contact and the second contact may be switched between a first voltage that is lower (e.g., slightly lower) than the breakdown voltage of the junction and a second voltage that is higher than the breakdown voltage (e.g., high enough for avalanche operation). In some embodiments, a reverse bias voltage is applied across the first contact and the second contact. For example, the reverse bias may be from about 10V to about 200V.

[0104] In some embodiments, the anode or the cathode or both the anode and the cathode may be electrically connected to a quenching circuit and / or a recharging circuit. The quenching operation may be active or passive. The recharging operation may be active or passive.

[0105] In some embodiments, a barrier or isolation region may be formed between adjacent photodiodes. Without loss of generality, the barrier may be provided in the form of a trench, a passivated trench, a filled trench, a filled passivated trench, an electric field defined by electrodes on the front surface of a wafer (e.g., a silicon material wafer), an electric field defined by electrodes on the back surface of the wafer, an electric field defined by electrodes on or in the trench, and an electric field defined by charged silicon vias.

[0106] In some embodiments, a photodiode array may include a silicon material having an incident light surface, a photodiode formed by a semiconductive junction in the silicon material and defining a respective pixel of the photodiode array, and a textured region coupled to the silicon material and positioned to interact with electromagnetic radiation. The semiconductor junction (or a portion thereof) of the photodiode array is configured to be biased beyond the breakdown voltage such that when there is a sufficiently instantaneous group of photons having at least one wavelength in the range from about 800 nm to about 1200 nm that impinge on each of the junctions in the junction, the respective semiconductor junction generates an electrical signal of optical power independent of the sufficiently instantaneous group of photons.

[0107] In some embodiments, a photodiode array may include a silicon material having an incident light surface, at least two photodiodes in the silicon material that define pixels of the photodiode array (each photodiode including a respective semiconductor junction), and a textured region coupled to the silicon material and positioned to interact with electromagnetic radiation. The semiconductor junction (or a portion thereof) of the photodiode array is configured to be biased beyond the breakdown voltage such that when there is a sufficiently instantaneous group of photons having at least one wavelength in the range from about 800 nm to about 1200 nm that impinge on each of the junctions in the junction, the respective semiconductor junction generates an electrical signal of optical power independent of the sufficiently instantaneous group of photons.

[0108] In some embodiments, the silicon material may have a thickness ranging from about 1 μm to about 100 μm. In some embodiments, each pixel of the photodiode array may include four photodiodes forming a four-array. In some embodiments, the four photodiodes of the four-array may be selective to detect a single wavelength range.

[0109] In some embodiments, the photodiode array may include an array and system as described in U.S. Patent Application No. 2019 / 0250257, which is incorporated herein by reference, wherein the silicon wafer including the SPAD device further includes a textured region that is coupled to the silicon material and is positioned to interact with electromagnetic radiation. In some embodiments, the wafer including the SPAD device may be illuminated from the back side. In some embodiments, the wafer including the SPAD device may include only SPAD devices (e.g., the wafer may have no non-SPAD devices), and the wafer including the SPAD device may be further bonded and / or electrically interconnected to a second wafer that includes circuitry configured to operate a LIDAR system.

[0110] Various embodiments have been described herein with reference to the accompanying drawings, in which example embodiments are shown. However, these embodiments may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the inventive concept to those skilled in the art. Various modifications to the example embodiments and the general principles and features described herein will be apparent. In the drawings, the dimensions and relative dimensions of layers and regions are not shown to scale and, in some instances, may be exaggerated for clarity. Throughout the text, like reference numerals may refer to like elements.

[0111] Example embodiments are mainly described in accordance with the specific methods and devices provided in a particular embodiment. However, these methods and devices may operate effectively in other embodiments. Phrases such as "some embodiments", "one embodiment", and "another embodiment" may refer to the same or different embodiments and may refer to multiple embodiments. Embodiments will be described with respect to a system and / or device having certain components. However, the system and / or device may include fewer or more components than those shown, and variations may be made to the arrangement and type of components without departing from the scope of the inventive concept. Example embodiments will also be described in the context of a particular method having certain steps or operations. However, the method and device may operate effectively for other methods having different and / or additional steps / operations and steps / operations in a different order that are inconsistent with the example embodiments. Thus, the inventive concept is not intended to be limited to the embodiments shown, but rather to conform to the broadest scope consistent with the principles and features described herein.

[0112] It will be understood that when an element is referred to or shown as "on another element", "connected" to another element or "coupled" to another element, it can be directly on the other element, connected to the other element or coupled to the other element, or there may be intervening elements. In contrast, when an element is referred to as "directly on another element", "directly connected" to another element or "directly coupled" to another element, there are no intervening elements.

[0113] It will also be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0114] In addition, relative terms such as "lower" or "bottom" and "upper" or "top" may be used herein to describe the relationship of one element to another as shown in the drawings. It will be understood that relative terms are intended to cover different orientations of the device in addition to the orientation depicted in the drawings. For example, if the device in one of the drawings is flipped, an element described as on the "lower" side of other elements will be oriented on the "upper" side of the other elements. Thus, depending on the specific orientation of the drawing, the exemplary term "lower" may cover both the "lower" and "upper" orientations. Similarly, if the device in one of the drawings is flipped, an element described as "below" or "beneath" other elements will be oriented "above" the other elements. Thus, the exemplary terms "below" or "beneath" may cover both the above and below orientations.

[0115] The terms used in the description of the present invention herein are for the purpose of describing particular embodiments only and are not intended to limit the present invention. As used in the specification and claims of the present invention, the singular forms "a", "an" and "the" are also intended to include the plural forms unless the context clearly indicates otherwise.

[0116] It will also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that when the terms "include", "including", "comprise" and / or "comprising" are used in this specification, the presence of the stated features, integers, steps, operations, elements and / or components is specified, but the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof is not excluded.

[0117] This description of embodiments of the present invention refers to the accompanying drawings, which are schematic illustrations of idealized embodiments (and intermediate structures) of the present invention. Thus, for example, variations in the shapes of the illustrations due to manufacturing techniques and / or tolerances are to be expected. Accordingly, the regions shown in the drawings are schematic in nature, and their shapes are not intended to depict the actual shape of regions of the device, nor are they intended to limit the scope of the present invention.

[0118] Unless otherwise defined, all terms (including technical and scientific terms) used in the disclosure of embodiments of the present invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, and are not necessarily limited to the specific definitions known at the time of describing the present invention. Thus, these terms may include equivalent terms created after such time. It will be further understood that terms (as defined in common dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. All patents and / or publications mentioned are hereby incorporated by reference.

[0119] Numerous different embodiments have been disclosed herein in connection with the above description and the accompanying drawings. It will be understood that a literal description and illustration of every combination and sub - combination of these embodiments would be inappropriately repetitive and confusing. Accordingly, this specification, including the drawings, should be construed as constituting a complete written description of all combinations and sub - combinations of the embodiments of the present invention described herein, and of the manner and process of making and using them, and should support claims to any such combination or sub - combination.

[0120] Although the present invention has been described herein with reference to various embodiments, it will be recognized that further variations and modifications can be made within the scope and spirit of the principles of this invention. Although specific terms have been employed, they are used in a general and descriptive sense only and not for purposes of limitation.

Claims

1. A photodetector device, comprising: a semiconductor material layer; at least one photodiode in the semiconductor material layer, the at least one photodiode being configured to be reverse-biased beyond a breakdown voltage of a semiconductor junction of the at least one photodiode to generate a corresponding electrical signal in response to detecting incident photons, wherein the corresponding electrical signal is independent of an optical power of the incident photons; and a textured region, the textured region being coupled to the semiconductor material layer and the textured region including an optical structure that is positioned to interact with the incident photons when the incident photons are detected by the at least one photodiode, and the optical structure being configured to increase an optical path length of the incident photons in the semiconductor material layer before the incident photons are detected by the at least one photodiode as compared to a distance that the incident photons travel directly from a surface of the semiconductor material layer on which the incident photons are incident to the at least one photodiode.

2. The photodetector device according to claim 1, wherein the at least one photodiode includes two or more photodiodes that define a pixel of the photodetector device, wherein the optical structure is configured to direct the incident photons to any one of the two or more photodiodes of the pixel for detection thereby.

3. The photodetector device according to claim 2, further comprising: a corresponding isolation region that separates the pixel from adjacent pixels of the photodetector device, wherein there is no such corresponding isolation region between the two or more photodiodes of the pixel.

4. The photodetector device according to claim 3, wherein the corresponding isolation region includes a corresponding deep trench isolation (DTI) region and further includes: a shallower trench isolation (SrTI) structure between the two or more photodiodes in the pixel, wherein the corresponding DTI region protrudes away from the two or more photodiodes beyond the SrTI structure.

5. The photodetector device according to claim 3, wherein in response to the incident photons being detected by any one of the two or more photodiodes, the corresponding electrical signal generated by any one of the two or more photodiodes is configured to be output to a corresponding processing path that includes corresponding electronic circuit elements not shared by the two or more photodiodes of the pixel.

6. The photodetector device according to claim 5, further comprising: a readout wafer that includes the corresponding electronic circuit elements, wherein the semiconductor material layer is stacked on a surface of the readout wafer.

7. The photodetector device according to claim 6, wherein the corresponding electronic circuit elements include a corresponding quenching circuit and / or a recharging circuit.

8. The photodetector device according to claim 6, further comprising: A metal layer structure, the metal layer structure being adjacent to the surface of the readout wafer in the readout wafer, wherein the metal layer structure extends under the two or more photodiodes and the metal layer structure is configured to provide an electrical signal to the two or more photodiodes or provide an electrical signal from the two or more photodiodes.

9. The photodetector device according to claim 8, wherein, The corresponding electronic circuit elements include an analog time integrator or an analog counter, and the metal layer structure includes integrating or counting the capacitors of the analog time integrator or the analog counter.

10. The photodetector device according to any one of claims 2 to 9, wherein, The optical structure is configured to direct the incident photons away from one of the two or more photodiodes of the pixel before detection by any one of the two or more photodiodes.

11. The photodetector device according to claim 10, wherein, The optical structure is a diffraction element, the diffraction element respectively includes one or more dimensions smaller than the wavelength of the incident photons, and the diffraction element includes an inverted pyramid array (IPA) structure.

12. The photodetector device according to claim 2, wherein, At least one of the two or more photodiodes in the pixel is configured to be disabled independently of each other.

13. The photodetector device according to claim 12, further comprising: A trench isolation region that separates the pixel from adjacent pixels of the photodetector device; and A first electrode and a second electrode, the first electrode and the second electrode are configured to apply a reverse bias to at least one of the two or more photodiodes of the pixel based on the voltage difference between the first electrode and the second electrode, wherein the voltage difference switches between a first voltage and a second voltage, the first voltage is greater than the breakdown voltage, and the second voltage is less than the breakdown voltage.

14. The photodetector device according to any one of claims 2-9 and 11-13, wherein, The at least one photodiode includes at least one single photon avalanche detector (SPAD), the at least one single photon avalanche detector has a corresponding semiconductor junction, and the semiconductor junction includes a planar region and a guard ring structure at the edge of the region.

15. The photodetector device according to any one of claims 2-9 and 11-13, wherein, The photodetector device includes an optical sensor array, the optical sensor array includes at least one photodiode between a plurality of pixels of the optical sensor array, wherein the optical sensor array is a light detection and ranging (LIDAR) detector array, and the source of the incident photons is a LIDAR transmitter array.

16. An optical sensor array, the optical sensor array Comprising: A plurality of pixels, each of the pixels including two or more photodiodes in a semiconductor material layer, the two or more photodiodes being configured to generate respective electrical signals in response to incident photons, wherein the respective electrical signals are independent of the optical power of the incident photons; and Respective isolation regions that separate adjacent pixels among the pixels; Wherein an optical structure is positioned between the respective isolation regions, and the optical structure is configured to direct the incident photons to any one of the two or more photodiodes of each pixel among the pixels and is configured to increase the optical path length of the incident photons in the semiconductor material layer before the incident photons are detected by the two or more photodiodes as compared to the distance that the incident photons travel directly from the surface of the semiconductor material layer on which the incident photons are incident to the two or more photodiodes.

17. The optical sensor array according to claim 16, Wherein, There is no respective isolation region between the two or more photodiodes of the pixel, and wherein the optical structure is configured to direct the incident photons away from one of the two or more photodiodes of each pixel among the pixels before detection by any one of the two or more photodiodes.

18. The optical sensor array according to claim 16, Wherein, The respective isolation regions include respective deep trench isolation (DTI) regions and further include: A shallower trench isolation (SrTI) structure between the two or more photodiodes in the pixel, wherein the respective DTI regions project beyond the SrTI structure away from the two or more photodiodes.

19. The optical sensor array according to claim 17, Wherein, The optical structure is a diffraction element, the diffraction element respectively including one or more dimensions smaller than the wavelength of the incident photons, and wherein the diffraction element is configured to direct the incident photons to any one of the two or more photodiodes of each pixel among the pixels with an optical path length greater than the distance between the surface of the optical sensor array and the one photodiode among the two or more photodiodes.

20. The optical sensor array according to claim 16, Wherein, The two or more photodiodes respectively include a semiconductor junction, the semiconductor junction including a planar region and a guard ring structure at an edge of the region, and the semiconductor junction is configured to be reverse biased beyond the breakdown voltage of the semiconductor junction to generate the respective electrical signals in response to the incident photons.

21. The optical sensor array according to claim 20, Wherein, In response to the incident photons being detected by any one of the two or more photodiodes, the corresponding electrical signals generated by any one of the two or more photodiodes are configured to be output to corresponding processing paths, and the corresponding processing paths include corresponding electronic circuit elements that are not shared by the two or more photodiodes of each pixel in the pixel.

22. The optical sensor array according to claim 21, wherein, the pixel, the corresponding isolation region, and the optical structure are disposed in or on a first semiconductor layer, and the optical sensor array further includes: a second semiconductor layer including corresponding electronic circuit elements, wherein the first semiconductor layer is bonded to the surface of the second semiconductor layer.

23. The optical sensor array according to claim 22, wherein, the second semiconductor layer further includes a controller configured to receive the corresponding electrical signals generated by the two or more photodiodes of each pixel in the pixel and perform temporal correlation between the corresponding arrival times indicated by the corresponding electrical signals.

24. The optical sensor array according to any one of claims 16 to 21, wherein, the optical sensor array is a light detection and ranging (LIDAR) detector array, and the source of the incident photons is a flash LIDAR transmitter array.

25. The optical sensor array according to any one of claims 16 to 21, wherein, the optical sensor array is a light detection and ranging (LIDAR) detector array, and the source of the incident photons is a scanning LIDAR transmitter array.

26. A light detection and ranging (LIDAR) detector array, the light detection and ranging (LIDAR) detector array comprises: a plurality of pixels in a semiconductor material layer having a thickness of 1 μm to 100 μm, the pixels each include at least one photodiode defined by a semiconductor junction, the semiconductor junction includes a planar region and a guard ring structure at the edge of the region, and the semiconductor junction is configured to generate an electrical signal in response to incident photons when a reverse bias applied to the semiconductor junction exceeds the breakdown voltage of the semiconductor junction, the incident photons including wavelengths between 800 nanometers (nm) and 1200 nm, wherein the electrical signal is independent of the optical power of the incident photons; corresponding deep trench isolation regions separating adjacent pixels among the pixels; and a first contact and a second contact adjacent to the corresponding deep trench isolation region in each pixel of the pixels, wherein the first contact and the second contact are configured to apply the reverse bias to the semiconductor junction based on a voltage difference between the first contact and the second contact. Wherein, the optical structure includes a diffractive optical element positioned between the pixel and the source of the incident photons and configured to increase the optical path length of the incident photons in the semiconductor material layer before the incident photons are detected by the at least one photodiode as compared to the distance that the incident photons travel directly from the surface of the semiconductor material layer, on which the incident photons are incident, to the at least one photodiode.

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