Single photon avalanche diode device

Abstract

A single photon avalanche diode device comprises an N-type diffusion layer, a P-type diffusion layer, a P-type epitaxial layer, a P-type substrate, an annular P well region, a deep groove isolation region DTI ring and an avalanche amplification region, the bottom of the deep groove isolation region DTI ring is provided with the P-type substrate, the region between the deep groove isolation region DTI ring and the P-type substrate is provided with the P-type epitaxial layer, the top of the P-type epitaxial layer is provided with the P-type diffusion layer, and the avalanche amplification region is provided with the annular P well region. An N-type diffusion layer is arranged on the top of the P-type diffusion layer, and an avalanche amplification region is arranged at the joint of the P-type diffusion layer and the N-type diffusion layer. The annular P well region in the structure does not need to be connected to the substrate at the bottommost part, so that the process difficulty is greatly reduced; a through reaction junction structure is directly formed between the first P end and the N end, a depletion region is expanded, and the detection efficiency of the device can be improved; photoconduction can be realized between the first P end and the second P end through voltage regulation and control, more photoelectrons are collected for the reaction junction, and the detection efficiency of the device can be further improved.

Description

Technical Field

[0001] The invention belongs to the field of single photon avalanche diodes, in particular to a single photon avalanche diode device. Background Art

[0002] In recent years, with the rise of technologies such as autonomous driving, many distance measurement methods represented by laser distance measurement have also become a popular research field with great appeal and research value. One of the most mainstream is the TOF (time of flight) laser distance measurement image sensor, which uses laser as the light source and calculates the distance information of the target by recording the time from the laser being emitted to the time it is reflected on the surface of the object and then returned to the image sensor. TOF distance measurement technology has the characteristics of high precision and low latency, which has also made TOF technology widely concerned.

[0003] Imaging technology based on single photon avalanche diode (Single Photon Avalanche Diode) is a new imaging technology today. Single photon avalanche diode image sensors have high sensitivity and time resolution, which are very suitable for TOF image sensor requirements. A TOF distance image sensor based on SPAD can be implemented using a SPAD pixel array, which uses CMOS (complementary metal oxide semiconductor) semiconductor integration technology to form multiple SPAD pixels, each of which contains an avalanche photodiode element and is arranged on a planar surface. SPAD has single-photon response capability and can effectively detect weak reflected signals at long distances or low laser power. The current SPAD device structure has been well optimized in terms of detection efficiency. At present, a similar SPAD device structure has been prepared and verified by Sony, but its DTI ring sidewall needs to be fully injected with a layer of p-type region from top to bottom, which is difficult to process. Most production machines cannot meet this condition, resulting in a high difficulty in the production process, high production cost, and low production efficiency. Summary of the invention

[0004] The present invention provides a single photon avalanche diode device to solve the defects in the prior art.

[0005] The present invention is achieved through the following technical solutions:

[0006] A single-photon avalanche diode device comprises an N-type diffusion layer, a P-type diffusion layer, a P-type epitaxial layer, a P-type substrate, an annular P-well region, a deep trench isolation region DTI ring, and an avalanche amplification region. A P-type substrate is arranged at the bottom of the deep trench isolation region DTI ring, a P-type epitaxial layer is arranged in the region between the deep trench isolation region DTI ring and the P-type substrate, a P-type diffusion layer is arranged on the top of the P-type epitaxial layer, an N-type diffusion layer is arranged on the top of the P-type diffusion layer, an avalanche amplification region is arranged at the connection between the P-type diffusion layer and the N-type diffusion layer, an annular P-well region is arranged on the inner side of the upper part of the deep trench isolation region DTI ring, and the annular P-well region is arranged on the outer side of the upper part of the P-type epitaxial layer. The N-type diffusion layer can be connected to the N end, the N-type diffusion layer can be connected to the N end, and the P-type epitaxial layer can be directly or indirectly connected to the P end.

[0007] In the single-photon avalanche diode device as described above, the top portion of the N-type diffusion layer protrudes through the first contact hole CT and is connected to the first conductive metal layer M to form an N terminal; the P-type substrate is connected to the metal layer BMG through the opening BV to form a first P terminal.

[0008] In a single-photon avalanche diode device as described above, the top portion of the N-type diffusion layer protrudes through the first contact hole CT and is connected to the first conductive metal layer M to form an N terminal; an SP heavily doped region is arranged in the annular P well region, and the SP heavily doped region is connected to the second conductive metal layer M through the second contact hole CT to form a second P terminal.

[0009] In a single-photon avalanche diode device as described above, the top portion of the N-type diffusion layer protrudes and is connected to the first conductive metal layer M through the first contact hole CT to form an N terminal; the P-type substrate is connected to the metal layer BMG through the opening BV to form a first P terminal; an SP heavily doped region is set in the annular P well region, and the SP heavily doped region is connected to the second conductive metal layer M through the second contact hole CT to form a second P terminal.

[0010] In the single-photon avalanche diode device as described above, an annular P channel is arranged between the annular P-well region and the P-type substrate, the annular P channel is located at the periphery of the P-type epitaxial layer, and the annular P-well region and the P-type substrate can be connected through the annular P channel.

[0011] The advantages of the present invention are: the annular P-well region in the structure of the present invention does not need to be connected to the bottom substrate, which greatly reduces the process difficulty; a through-type reaction junction structure is directly formed between the first P terminal and the N terminal of the present invention, the depletion region is expanded, and the detection efficiency of the device can be improved; photoconductivity can be achieved between the first P terminal and the second P terminal of the present invention through voltage regulation, so that more photoelectrons are collected for the reaction junction, which can further improve the detection efficiency of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0013] Figure 1 is a schematic structural diagram of embodiment 1 of the present invention;

[0014] Figure 2 is a schematic structural diagram of Embodiment 2 of the present invention;

[0015] Figure 3 is a schematic structural diagram of Embodiment 3 of the present invention;

[0016] Figure 4 is a schematic structural diagram of embodiment 4 of the present invention;

[0017] Figure 5 It is a schematic structural diagram of embodiment 5 of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Example 1

[0020] like Figure 1 As shown, it includes an N-type diffusion layer 101, a P-type diffusion layer 102, a P-type epitaxial layer 103, a P-type substrate 104, an opening BV 105, a metal layer BMG 106, a P-well region 107, a first conductive metal layer M108, a first contact hole CT 109, an avalanche amplification region 110 and a deep trench isolation region DTI ring 111.

[0021] The N-type diffusion layer 101 is a high-concentration N-type diffusion layer formed on the top of the P-epitaxial layer 103 and covers the top of the P-type diffusion layer 102. The top portion of the N-type diffusion layer 101 protrudes to the device surface and is connected to the first conductive metal layer M108 through the first contact hole CT109 to form the N-end of the device. The P-type diffusion layer 102 is a high-concentration P-type diffusion layer formed on the top of the epitaxial layer and covers the bottom of the N-type diffusion layer 101. An avalanche amplification region 110 is set at the connection between the N-type diffusion layer 101 and the P-type diffusion layer 102. The P-type epitaxial layer 103 can be obtained by growing and doping on the P substrate 104. The P-well region 107 is a P-type high-concentration diffusion layer, which is formed by surrounding the upper periphery of the P-type epitaxial layer 103. The periphery of the P-well region 107 is a deep trench isolation region DTI ring 111, which completely isolates the entire device from surrounding devices. The metal layer BMG 106 at the bottom of the device is directly connected to the bottom P-type substrate 104 through the opening BV 105 to form the P terminal of the device.

[0022] When the device is working, a voltage is applied to the N-terminal formed by the first conductive metal layer M108 and the P-terminal formed by the metal layer BMG 106. At this time, the voltage at the N-terminal of the device is higher than the voltage at the P-terminal of the device, so that the device works in the Geiger mode. When a photon arrives and is absorbed by the device, a hole-electron pair is generated. Under the action of the electric field, the hole-electron pair undergoes avalanche breakdown in the avalanche amplification region 110 through the multiplication effect, generating a large avalanche breakdown current to the outside.

[0023] Example 2

[0024] like Figure 2 As shown, it includes an N-type diffusion layer 201, a P-type diffusion layer 202, a P-type epitaxial layer 203, a P-type substrate 204, an opening BV 205, a metal layer BMG 206, a P-well region 207, a first conductive metal layer M208, a first contact hole CT 209, an avalanche amplification region 210, a deep trench isolation region DTI ring 211 and a ring-shaped P channel 212.

[0025] The N-type diffusion layer 201 and the P-type diffusion layer 202 are arranged on the top of the P-type epitaxial layer 203. The top part of the N-type diffusion layer 201 protrudes to reach the surface of the device and is connected to the first conductive metal layer M 208 through the first contact hole CT 209 to form the N end of the device. The metal layer BMG 206 at the bottom of the device is directly connected to the bottom P-type substrate 204 through the contact hole CT 205 to form the P end of the device. An annular P channel 212 is formed between the P-type substrate 204 and the P-well region 207 by doping. The annular P channel 212 is arranged on the periphery of the P-type epitaxial layer 203. The periphery of the P-well region 207 is a deep trench isolation region DTI ring 314, which completely isolates the entire device from surrounding devices.

[0026] When the device is working, a voltage is applied through the first conductive metal layer M 208 and the metal layer BMG 206, that is, a voltage is applied to the P terminal and the N terminal of the device, so that an electric field can be formed in the device. When photons reach the device and are absorbed by the device, hole-electron pairs are generated, and the electrons are transferred under the action of the electric field and enter the avalanche amplification region, resulting in avalanche breakdown.

[0027] Example 3

[0028] like Figure 3 As shown, it includes an N-type diffusion layer 301, a P-type diffusion layer 302, a P-type epitaxial layer 303, a P-type substrate 304, an opening BV 305, a metal layer BMG 306, an SP heavily doped region 307, a P-well region 308, a first contact hole CT 309, a first conductive metal layer M 310, a first contact hole CT 311, a second conductive metal layer M 312, an avalanche amplification region 313 and a deep trench isolation region DTI ring 314.

[0029] The N-type diffusion layer 301 and the P-type diffusion layer 302 are arranged on the top of the P-type epitaxial layer 303, and the top part of the N-type diffusion layer 301 protrudes and is connected to the first conductive metal layer M 310 through the first contact hole CT 309 to form the N end of the device. The P-type diffusion layer 302 is a high-concentration P-type diffusion layer formed on the top of the P-type epitaxial layer 303 and covers the bottom of the N-type diffusion layer 301. An avalanche amplification region 313 is formed at the connection between the N-type diffusion layer 301 and the P-type diffusion layer 302. The metal layer BMG 306 at the bottom of the device is directly connected to the bottom P-type substrate 304 through the opening BV 305 to form the P end of the device. The P-well region 308 is a P-type high-concentration diffusion layer, which is formed on the surface of the device in a manner of surrounding the outer periphery of the P-type epitaxial layer 303. There is an SP heavily doped region 307 in the middle of the P-well region through the second contact hole CT 311 is connected to the second conductive metal layer M312 to form the second P terminal of the device. The periphery of the P well region 308 is a deep trench isolation region DTI ring 314, which completely isolates the entire device from surrounding devices to form a three-terminal device.

[0030] When the device is working, voltage is applied to the first conductive metal layer M 310, the second conductive metal layer M 312 and the metal layer BMG 306, so that the device works in Geiger mode. At this time, the voltage at the second conductive metal layer M312 is slightly higher than the voltage at the metal layer BMG 306, and a photoconductor is formed between the P well region 308 and the P substrate 304 to improve the electron transfer efficiency. When a photon arrives and is absorbed by the device, a hole-electron pair is generated. Under the action of the electric field, the hole-electron pair undergoes avalanche breakdown in the avalanche amplification region 313 through the multiplication effect, and a large avalanche breakdown current is generated externally.

[0031] Example 4

[0032] like Figure 4 As shown, it includes an N-type diffusion layer 401, a P-type diffusion layer 402, a P-type epitaxial layer 403, a P-type substrate 404, an SP heavily doped region 405, a P-well region 406, a first contact hole CT 407, a first conductive metal layer M 408, a second contact hole CT 409, a second conductive metal layer M 410, an avalanche amplification region 411 and a deep trench isolation region DTI ring 412.

[0033] The N-type diffusion layer 401 and the P-type diffusion layer 402 are arranged on the top of the P-type epitaxial layer 403, and the N-type diffusion layer 401 can cover the top of the P-type diffusion layer 402. An avalanche amplification region 411 is arranged at the middle connection between the N-type diffusion layer 401 and the P-type diffusion layer 402. The surface of the N-type diffusion layer partially protrudes and is connected to the first conductive metal layer M 408 through a first contact hole CT 407 to form the N end of the device. A P-well region 406 is arranged on the upper periphery of the P-type epitaxial layer 403, which is a high-concentration P diffusion layer, and an SP heavily doped region 405 is arranged in the middle of the P-well region 406, which can be connected to the second conductive metal layer M 410 through a second contact hole CT 409 to form the P end of the device. The periphery of the P-well region 406 is a deep trench isolation region DTI ring 412, which completely isolates the entire device from surrounding devices.

[0034] When the device is working, corresponding voltages are applied across the P terminal formed by the second conductive metal layer M 410 and the N terminal formed by the first conductive metal layer M 408, so that the device works in the Geiger mode. When a photon arrives and is absorbed by the device, a hole-electron pair is generated. Under the action of the electric field, the hole-electron pair undergoes avalanche breakdown in the avalanche amplification region 411 through the multiplication effect, generating a large avalanche breakdown current to the outside.

[0035] Example 5

[0036] like Figure 5 As shown, it includes an N-type diffusion layer 501, a P-type diffusion layer 502, a P-type epitaxial layer 503, a P-type substrate 504, an SP heavily doped region 505, a P-well region 506, a first contact hole CT 507, a first conductive metal layer M 508, a second contact hole CT 509, a second conductive metal layer 510, an avalanche amplification region 511, a deep trench isolation region DTI ring 512 and an annular P channel 613.

[0037] The N-type diffusion layer 501 and the P-type diffusion layer 502 are arranged on the top of the P-type epitaxial layer 503, and the N-type diffusion layer 501 covers the top of the P-type diffusion layer 502. An avalanche amplification region 511 is arranged at the middle connection between the N-type diffusion layer 502 and the P-type diffusion layer 502. The surface of the N-type diffusion layer 501 partially protrudes and is connected to the first conductive metal layer M 508 through a first contact hole CT 507 to form the N end of the device. A P-well region 506 is arranged on the upper periphery of the P-type epitaxial layer 503, which is a high-concentration P diffusion layer, and an SP heavily doped region 505 is arranged in the P-well region 506, which can be connected to the second conductive metal layer M 508 through a second contact hole CT 509. 510 is connected to form the P end of the device, and an annular P channel 513 is formed between the P well region 506 and the P substrate 504 by doping. The annular P channel 513 is arranged at the periphery of the P-type epitaxial layer 503, and a deep trench isolation region DTI ring 512 is arranged at the periphery of the annular P channel 513 to completely isolate the entire device from surrounding devices.

[0038] When the device is working, corresponding voltages are applied across the P terminal formed by the second conductive metal layer M510 and the N terminal formed by the first conductive metal layer M508, so that the device works in the Geiger mode. When a photon arrives and is absorbed by the device, a hole-electron pair is generated. Under the action of the electric field, the hole-electron pair undergoes avalanche breakdown in the avalanche amplification region 511 through the multiplication effect, generating a large avalanche breakdown current to the outside.

[0039] It can be seen from Examples 1-5 that in the present invention, under the Geiger mode, that is, the applied voltage is higher than the breakdown voltage of the device, when a photon arrives and is absorbed by the device, a hole-electron pair is generated, and the electron enters the avalanche amplification region under the action of the electric field, avalanche amplification occurs, and there is a certain probability of generating a continuous avalanche breakdown. After being processed by the pulse shaping and quenching circuits, a digital pulse signal can be generated. By detecting the time interval of the pulse generation, high-precision distance information can be calculated to ensure the accuracy of the present invention when used.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A single photon avalanche diode device, characterized in that: The invention comprises an N-type diffusion layer, a P-type diffusion layer, a P-type epitaxial layer, a P-type substrate, an annular P-well region, a deep trench isolation region DTI ring, and an avalanche amplification region. A P-type substrate is arranged at the bottom of the deep trench isolation region DTI ring, a P-type epitaxial layer is arranged in the region between the deep trench isolation region DTI ring and the P-type substrate, a P-type diffusion layer is arranged on the top of the P-type epitaxial layer, an N-type diffusion layer is arranged on the top of the P-type diffusion layer, an avalanche amplification region is arranged at the connection between the P-type diffusion layer and the N-type diffusion layer, an annular P-well region is arranged on the inner side of the upper part of the deep trench isolation region DTI ring, and the annular P-well region is arranged on the outer side of the upper part of the P-type epitaxial layer, the N-type diffusion layer can be connected to the N end, the N-type diffusion layer can be connected to the N end, and the P-type epitaxial layer can be directly or indirectly connected to the P end.

2. A single photon avalanche diode device according to claim 1, characterized in that: The top part of the N-type diffusion layer protrudes and is connected to the first conductive metal layer M through the first contact hole CT to form an N terminal; the P-type substrate is connected to the metal layer BMG through the opening BV to form a first P terminal.

3. The single photon avalanche diode device according to claim 1, characterized in that: The top part of the N-type diffusion layer protrudes and is connected to the first conductive metal layer M through the first contact hole CT to form an N terminal; an SP heavily doped region is set in the annular P well area, and the SP heavily doped region is connected to the second conductive metal layer M through the second contact hole CT to form a second P terminal.

4. The single photon avalanche diode device according to claim 1, characterized in that: The top part of the N-type diffusion layer protrudes and is connected to the first conductive metal layer M through the first contact hole CT to form an N terminal; the P-type substrate is connected to the metal layer BMG through the opening BV to form a first P terminal; an SP heavily doped region is set in the annular P well area, and the SP heavily doped region is connected to the second conductive metal layer M through the second contact hole CT to form a second P terminal.

5. The single photon avalanche diode device according to claim 1, characterized in that: An annular P channel is provided between the annular P well region and the P type substrate. The annular P channel is located at the periphery of the P type epitaxial layer. The annular P well region and the P type substrate can be connected through the annular P channel.

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