Single-photon avalanche diode comprising p-doped region and 1-side spot ohmic metal contact

Abstract

The present invention relates to a P-doped region and a 1-side spot ohmic metal contact structure which are applicable to a single-photon avalanche diode sensor. It is possible to enhance photon absorption efficiency while minimizing the size of a single-photon avalanche diode, by forming a P-doped region and placing an ohmic metal contact in a spot form on an edge of the P-doped region.

Description

Single-photon avalanche diode including P-type doping and 1-side spot ohmic metal contacts

[0001] The present invention relates to a single-photon avalanche diode comprising P-type doping and a 1-side spot ohmic metal contact, and more specifically, to a technology that improves light detection efficiency and reliability by minimizing the cross-sectional area and contact resistance of a single-photon avalanche diode.

[0002] Single Photon Avalanche Diodes (SPADs) are a technology capable of detecting single photons and providing high sensitivity and fast response speeds, playing a crucial role in various advanced fields such as LiDAR, quantum communication, and life science imaging. In particular, SPADs have established themselves as essential components for high-precision sensing and imaging technologies because they can detect reliable signals even at low light intensities. Due to this technological importance, research to improve the performance of SPADs is continuously being conducted, and recently, semiconductor process technologies and structural optimization aimed at miniaturization and improved detection efficiency are being actively pursued.

[0003] However, conventional single-photon avalanche diode structures have several limitations. Notably, there is a problem with the increased device size due to symmetric P-type doping and the arrangement of ohmic metal contacts. As the device size increases, integration density decreases, which acts as a major constraint in modern electronic devices and sensor technologies that require miniaturization. Furthermore, as the device size increases, the fill factor (FF) decreases, which can reduce the overall detection efficiency of the device.

[0004] Furthermore, in existing structures, metal contacts are widely distributed, which obscures the light absorption region. This acts as a major cause of reduced photon absorption efficiency and consequently negatively impacts the sensitivity and performance of single-photon avalanche diodes. In particular, the reduction in the light absorption region weakens the core function required for single-photon avalanche diodes to detect single photons, which acts as a limiting factor in their utilization in high-performance sensing and imaging applications. These issues remain challenges that must be addressed for the advancement of single-photon avalanche diode technology and the expansion of its applications.

[0005] [Prior Art Literature]

[0006] [Patent Literature]

[0007] (Patent Document 1) US 2009-0189207 A1

[0008] The object of the present invention is to provide a single photon avalanche diode comprising: a P-doping region; and an ohmic metal contact in the form of a spot at the edge of the P-doping region, wherein the P-doping region has a non-uniform periphery shape, and the distance from a predetermined center point to the outermost edge of the P-doping region has a maximum value at the portion in contact with the ohmic metal contact.

[0009] To solve the problem of the present invention, the present invention provides a single photon avalanche diode comprising: a P-doping region; and an ohmic metal contact in the form of a spot at the edge of the P-doping region, wherein the P-doping region has a non-uniform periphery shape, and the distance from a predetermined center point to the outermost edge of the P-doping region has a maximum value at the portion in contact with the ohmic metal contact.

[0010] The present invention relates to a single-photon avalanche diode comprising P-type doping and a 1-side spot ohmic metal contact. By contacting the ohmic metal contact in a spot form at the edge within the P-type doping region, the size of the single-photon avalanche diode can be reduced. Additionally, by positioning the ohmic metal contact to minimize the coverage of the photon absorption region, the photon absorption efficiency can be improved.

[0011] FIG. 1 is a schematic diagram illustrating a conventional single-photon avalanche diode (10).

[0012] FIG. 2 is a schematic diagram illustrating a single-photon avalanche diode (20) of the present invention. The P-doping region (200) represents a region including a deep P-doping (201) region, a shallow P-doping (202) region, and an ohmic metal contact (203) region.

[0013] FIG. 3a compares the cross-sectional areas of the conventional single-photon avalanche diode (10) and the single-photon avalanche diode (20) of the present invention. FIG. 3b compares the sizes of the ohmic metal contact regions of the conventional single-photon avalanche diode (10) and the single-photon avalanche diode (20) of the present invention.

[0014] Hereinafter, a single-photon avalanche diode (20) including a P-type doping (200) and an ohmic metal contact (203) according to an embodiment of the present invention will be described in detail with reference to the attached drawings. However, the attached drawings are merely examples to aid in understanding the present invention, and the scope of the present invention is not limited to the specific form of the drawings.

[0015] According to FIG. 2, the present invention provides a single-photon avalanche diode (20) comprising a P-type doping region (200) and an ohmic metal contact (203). Specifically, the single-photon avalanche diode (20) is a device for detecting a single photon. The single-photon avalanche diode (20) is capable of detecting a single photon by applying a high-voltage bias. An ohmic metal contact is positioned in a spot shape on one side of the single-photon avalanche diode (20). The ohmic metal contact contacts the P-type doping region (200).

[0016] Specifically, the P-type doping region (200) may have a non-uniform periphery shape. The P-type doping region (200) generally has a point-symmetric shape with respect to a predetermined center point (C), for example, circular, but may not have a point-symmetric shape in the area in contact with the ohmic metal contact. The P-type doping region (200) may include an arc region centered on the center point (C) at its outermost edge and a remaining area. The P-type doping region (200) may have a shape in which the area in contact with the ohmic metal contact protrudes, and the remaining area is circular. The outermost edge of the P-type doping region (200) generally has a certain distance from the predetermined center point (C), but in the area in contact with the ohmic metal contact, it may have a distance greater than the predetermined center point (C). The distance from a predetermined center point (C) to the outermost edge of the P-type doping region (200) can have a maximum value at the area in contact with the ohmic metal contact.

[0017] This enables the miniaturization of the single-photon avalanche diode (20) while maintaining electric field uniformity.

[0018] According to one embodiment of the present invention, the P-type doping region (200) includes deep P-type doping (Deep P-doping; 201) and shallow P-type doping (Shallow P-doping; 202). Specifically, the deep P-type doping (201) region induces avalanche breakdown through the formation of an electric field and stabilizes the charge amplification region. The shallow P-type doping (Shallow P-doping; 202) provides low contact resistance and optimizes current flow.

[0019] According to one embodiment of the present invention, an ohmic metal contact (203) can facilitate current flow by contacting a shallow P-type doping region (202). Specifically, the ohmic metal contact (203) may be characterized by being positioned in a spot shape on one side of the single-photon avalanche diode (20) to minimize contact resistance. Through this, the photon absorption efficiency of the single-photon avalanche diode (20) can be increased.

[0020] According to one embodiment of the present invention, an ohmic metal contact is arranged in a spot shape on one side of a single-photon avalanche diode (20), so that when the P-type doping region (200) is formed in a non-uniform periphery structure, the cross-sectional area of ​​the single-photon avalanche diode can be formed to be reduced by 10 to 50% compared to the case where the P-type doping region is in a circular shape. As a result, the structure of the present invention can improve light absorption efficiency by securing an effective light detection area while reducing the cross-sectional area of ​​the single-photon avalanche diode.

[0021] According to one embodiment of the present invention, the ohmic metal contact (203) is formed as a metal layer that contacts a semiconductor substrate. Specifically, the metal layer may include a metal material of titanium (Ti), aluminum (Al), or nickel (Ni), but is not limited thereto. Each material may be selected considering electrical conductivity and bonding characteristics with the semiconductor surface. In particular, titanium (Ti) has excellent adhesion, aluminum (Al) provides low resistance, and nickel (Ni) has high oxidation resistance, enabling stable electrical contact.

[0022] According to one embodiment of the present invention, a single photon avalanche diode (20) may be formed from at least one of indium phosphorus (InP) or indium gallium arsenide (InGaAs) to provide optimal sensitivity in a specific optical wavelength band, but is not limited thereto.

[0023] According to one embodiment of the present invention, a single photon avalanche diode (20) can be used as a light receiving unit (Rx) of a LiDAR system. Generally, a LiDAR system operates by firing a laser pulse at a target object and then detecting the reflected light signal to obtain distance and three-dimensional spatial information. At this time, the light receiving detector (Rx Detector) is a key component that receives the reflected light signal and converts it into an electrical signal.

[0024] According to one embodiment of the present invention, the LiDAR system may be a LiDAR system operating in the Short-Wave Infrared (SWIR) band. For example, it may include a laser in the Short-Wave Infrared (SWIR) band and emit a laser beam with a wavelength of 1000 to 2500 nm. The Short-Wave Infrared band (1000 to 2500 nm) has less scattering in the atmosphere than visible light and has excellent transmission characteristics through certain materials (e.g., moisture, plastic, metal surfaces), enabling reliable light detection even in night and foggy environments.

[0025] According to one embodiment of the present invention, when a single-photon avalanche diode (20) is applied as a light receiving detector, it can detect even minute light signals at the single-photon level, thereby providing high sensitivity and low noise characteristics compared to conventional silicon photodiode (Si-PD) based detectors. In particular, the photon absorption efficiency of the single-photon avalanche diode (20) can be maximized through the P-type doping (200) region and the ohmic metal contact structure (203). Furthermore, the single-photon avalanche diode (20) of the present invention can provide reliable light detection performance in lidar systems requiring high resolution and long-range detection. Specifically, the single-photon avalanche diode (20) of the present invention improves light sensitivity and signal-to-noise ratio (SNR) compared to conventional photodiode-based light receiving detectors, thereby maintaining high performance even in long-range detection and low-light environments.

[0026] The single photon avalanche diode (20) of the present invention further provides high sensitivity and fast response speed, so it can be utilized in various applications such as LiDAR (Light Detection and Ranging) systems, medical imaging, quantum optics, high-speed imaging and photonic communication systems.

[0027]

[0028] *[Example 1] Application of P-type doping (200) and 1-side spot ohmic metal contact (203)

[0029] The present invention proposes a P-type doping (P-Doping; 200) region and a 1-side spot ohmic metal contact (203) structure applicable to a single photon avalanche diode (20), thereby improving the limitations of existing technology and increasing photon absorption efficiency.

[0030] - Increase in photon absorption efficiency through a 1-sidespot ohmic metal contact (203) structure

[0031] In conventional single-photon avalanche diodes (10), the ohmic metal contact (103) occupies a large area inside the single-photon avalanche diode (10), thereby limiting the area where photons can be incident. Specifically, in conventional technology, as the ohmic metal contact (103) is widely distributed, the effective photon absorption area where a single photon can be incident is reduced. Due to these structural constraints, there was a problem of reduced photon absorption efficiency.

[0032] In the present invention, an ohmic metal contact (203) is arranged in a spot shape on one side. As a result, the single photon avalanche diode (20) reduced the optically blocked area where photon absorption is obscured by the ohmic metal contact (203) of the present invention compared to the conventional ohmic metal contact (103) (Fig. 2). The photon detection area was maximized, and the photon absorption efficiency was improved compared to the conventional one.

[0033] - Applicable to high-speed and high-sensitivity LiDAR systems

[0034] According to one embodiment of the present invention, a P-type doping (200) region and a 1-side spot ohmic metal contact (203) structure were applied. Through this, signal detection performance in a high-speed and high-sensitivity LiDAR system could be maximized.

[0035] In particular, when applied to SWIR (Short-Wave Infrared) LiDAR systems, it was possible to detect signals with high sensitivity even at longer distances and provide performance optimized for autonomous driving and 3D environment recognition technology.

[0036] [Example 2] Confirmation of Footprint Reduction

[0037] In the present invention, by applying a P-type doping region (200) and an ohmic metal contact (203) of a single photon avalanche diode (20), it was confirmed that the same photon absorption efficiency can be maintained while reducing the footprint compared to existing technology.

[0038] In the conventional single-photon avalanche diode (10), the shallow P-type doping region (102) and the ohmic metal contact (103) were formed in a symmetrical circular shape. Consequently, unnecessary space was created, which increased the footprint of the single-photon avalanche diode (10). Specifically, as the footprint increased, the integration density per unit area decreased, which resulted in a problem where space utilization was limited in multi-pixel-based sensors.

[0039] In the present invention, an ohmic metal contact is arranged in a spot shape on one side, and accordingly, the structure is designed to form a non-uniform periphery of the P-type doping region (200).

[0040] To confirm the superiority of the structure of the present invention, the photon absorption efficiency of a conventional single-photon avalanche diode (10) and the single-photon avalanche diode (20) of the present invention was compared and analyzed.

[0041] As a result, according to FIG. 3a, it was confirmed that the same photon absorption efficiency is maintained or improved even though the footprint of the single photon avalanche diode (20) of the present invention is reduced by 10 to a maximum of 50% compared to the conventional one. Through this, it was found that it provides an important technical advantage of maximizing space utilization while maintaining the same performance.

[0042] [Example 3] Experiment comparing the size of the area covered by ohmic metal contacts

[0043] The difference in the light detection area according to the structure of the ohmic metal contact (203) was evaluated, and it was confirmed whether the present invention has the effect of minimizing the obscured area compared to the existing structure.

[0044] To compare the ohmic metal contact structure (203) of the single photon avalanche diode (20) of the present invention with a conventional structure, the area occupied by each ohmic metal contact was measured to determine the ratio of the optically blocked area.

[0045] Specifically, the ohmic metal contact area was measured through optical or scanning electron microscope (SEM) analysis, and the percentage (%) occupied by the metal contact in each structure was calculated. Based on this, the ratio of the occluded area of ​​the present invention compared to the existing one was confirmed.

[0046] As a result, according to FIG. 3b, it was confirmed that the ohmic metal contact structure (203) of the present invention is reduced to 30 to 10% of the total area of ​​the existing ohmic metal contact structure (103). Through this improvement, the photon absorption efficiency was increased.

[0047] The scope of the present invention is not limited to the embodiments described above but may be implemented in various forms of embodiments within the scope of the appended claims. It is deemed that the scope of the claims of the present invention includes various modifications that are possible by anyone with ordinary knowledge in the technical field to which the invention pertains, without departing from the essence of the invention claimed in the claims.

[0048] [Explanation of the symbol]

[0049] 10: Conventional single-photon avalanche diode

[0050] 101: Deep P-doping region of conventional single-photon avalanche diodes

[0051] 102: Shallow P-doping region of conventional single-photon avalanche diodes

[0052] 103: Ohmic Metal Contact of Conventional Single Photon Avalanche Diode

[0053] 20: Single-photon avalanche diode of the present invention

[0054] 200: P-type doping (Deep P-doping) region of the single-photon avalanche diode of the present invention

[0055] 201: Deep P-doping region of the single-photon avalanche diode of the present invention

[0056] 202: Shallow P-doping region of the single-photon avalanche diode of the present invention

[0057] 203: Ohmic Metal Contact of the Single Photon Avalanche Diode of the Present Invention

[0058] C: Center point of the deep P-doping region

Claims

1. P-type doping (P-doping) region; and Ohmic metal contact in the form of a spot at the edge of the P-type doping region; Includes. The above P-type doping region has a non-uniform periphery shape, and the distance from a predetermined center point to the outermost edge of the P-type doping region has a maximum value at the region in contact with the ohmic metal contact. Single Photon Avalanche Diode 2. In Paragraph 1, The non-uniform periphery shape of the above-mentioned P-type doping region includes an arc region centered on the predetermined center and a remaining region, and the P-type doping region contacts the ohmic metal contact in the remaining region. Single photon avalanche diode.

3. In Paragraph 1, The above P-type doping region includes a shallow P-type doping region and a deep P-type doping region, Single photon avalanche diode.

4. In Paragraph 3, The above ohmic metal contact is in contact with the above shallow P-doping region, Single photon avalanche diode.

5. In Paragraph 1, The above ohmic metal contact is formed of a metal layer, wherein the metal comprises at least one of titanium (Ti), aluminum (Al), or nickel (Ni). Single photon avalanche diode.

6. In Paragraph 1, A single-photon avalanche diode formed of at least one of indium phosphorus (InP) or indium gallium arsenide (InGaAs).

7. A LiDAR system comprising a single photon avalanche diode of any one of claims 1 to 6 as a light receiving unit (Rx).

8. In Paragraph 7, Operating in the Short-Wave Infrared (SWIR) band, LiDAR system.

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