CN118867029A - Single photon avalanche diode, manufacturing method thereof and photoelectric detector - Google Patents

Abstract

The invention discloses a single photon avalanche diode, a manufacturing method thereof and a photoelectric detector, wherein an isolation region is arranged to divide a first doping region, a second doping region, a third doping region and a fourth doping region into preset equal parts which are electrically isolated, and a hierarchy structure of the first doping region, the second doping region, the third doping region and the fourth doping region is arranged.

Description

Single photon avalanche diode, manufacturing method thereof and photoelectric detector

Technical Field

The invention relates to the technical field of photoelectric detection, in particular to a single photon avalanche diode, a manufacturing method thereof and a photoelectric detector.

Background

Single Photon Avalanche Diode (SPAD) is an important photoelectric device capable of detecting single photons. SPAD devices of different structures are continuously produced, so that the performance of the SPAD devices is also continuously improved. The working principle of the SPAD is that reverse bias voltage larger than Breakdown Voltage (BV) is applied to the SPAD so that the SPAD is in a Geiger mode, photon-generated carriers can be generated to trigger avalanche when single photons are incident, and the SPAD obtains extremely high current gain, so that the sensitive detection of single photons is realized. For SPAD array chips, the device size needs to be reduced to improve the image resolution on the same chip size, but when the device size is reduced to below 10um, higher requirements are placed on the design and manufacturing process of the device.

Disclosure of Invention

The invention mainly aims to provide a single photon avalanche diode, a manufacturing method thereof and a single photon avalanche detector, designs a SPAD device with position resolution capability, can be used as a plurality of sub SPAD, and improves the imaging resolution of the SPAD array chip under the condition of not reducing the whole size of the SPAD.

To achieve the above object, the present invention provides a single photon avalanche diode including:

A substrate of a first doping type, wherein an active region is electrically isolated from a first isolation region in the substrate;

The active region is provided with a first doping region and a second doping region with a second doping type, and is also provided with a third doping region and a fourth doping region with the first doping type, the first doping type is opposite to the second doping type, the doping concentration of the first doping region is higher than that of the second doping region, the doping concentration of the fourth doping region is higher than that of the third doping region and the substrate, the doping concentration of the third doping region is gradually increased along the direction away from the upper surface of the active region, and the first doping region and the fourth doping region are respectively used as an anode contact region and a cathode contact region according to the doping type;

The third doped region extends from the upper surface of the active region to the inside of the active region, the second doped region extends from the upper surface of the third doped region to the inside of the third doped region, the third doped region is surrounded by the third doped region with the width and the depth being larger than those of the second doped region, the first doped region extends from the upper surface of the second doped region to the inside of the second doped region, the second doped region with the width and the depth being larger than those of the first doped region, the fourth doped region extends from the upper surface of the active region to the inside of the active region along the whole edge of the first isolation region, and one side of the fourth doped region, which is far away from the first isolation region, is connected with one side of the third doped region, which is close to the first isolation region;

And a second isolation region is further arranged in the substrate, the second isolation region divides the first doped region, the second doped region, the third doped region and the fourth doped region into preset equal parts which are electrically isolated from each other, so that the active region is divided into sub-regions of the preset equal parts, and structures in the sub-regions respectively form a sub-single photon avalanche diode.

Optionally, the depth of the fourth doped region is smaller than the depth of the third doped region, a fifth doped region of the first doped type is further arranged in the active region, the doping concentration of the fifth doped region is smaller than that of the fourth doped region, the fifth doped region extends from the upper surface of the fourth doped region to the lower surface of the active region along the whole edge of the first isolation region, a part of the fifth doped region, which is away from the first isolation region, is connected with the third doped region, and the depth of the fifth doped region is larger than that of the third doped region.

Optionally, the first isolation region and the second isolation region are isolation regions formed by deep trench isolation.

Optionally, the orthographic projection of the active region on the upper surface of the substrate is rectangular, and the orthographic projection of the second isolation region on the upper surface of the substrate is cross-shaped, so as to divide the first doped region, the second doped region, the third doped region and the fourth doped region into 4 equal parts which are electrically isolated from each other.

Optionally, the first doping type is p-type doping and the second doping type is n-type doping.

In addition, to achieve the above object, the present invention further provides a method for manufacturing a single photon avalanche diode, for manufacturing the single photon avalanche diode described above, including:

providing the substrate, and demarcating the active area on the substrate;

Performing ion implantation in the active region, and forming a first ion implantation region, a second ion implantation region, a third ion implantation region and a fourth ion implantation region on the substrate, wherein the first ion implantation region extends from the upper surface of the active region to the inside of the active region, the second ion implantation region extends from the upper surface of the third ion implantation region to the inside of the third ion implantation region, is surrounded by the third ion implantation region with the width and the depth being larger than those of the second ion implantation region, the first ion implantation region extends from the upper surface of the second ion implantation region to the inside of the second ion implantation region, is surrounded by the second ion implantation region with the width and the depth being larger than those of the first ion implantation region, the fourth ion implantation region extends from the upper surface of the active region to the inside of the active region along one side of the third ion implantation region facing away from the second ion implantation region, and reaches the edge of the active region on one side of the fourth ion implantation region facing away from the third ion implantation region;

And manufacturing a first isolation region on the substrate along the outer edge of the active region, manufacturing a second isolation region on the substrate, wherein the second isolation region electrically isolates the first ion implantation region, the second ion implantation region, the third ion implantation region and the fourth ion implantation region from preset equal parts, and the first ion implantation region, the second ion implantation region, the third ion implantation region and the fourth ion implantation region which are isolated by the second isolation region are respectively used as the first doping region, the second doping region, the third doping region and the fourth doping region.

Optionally, performing ion implantation in the active region, and forming a first ion implantation region, a second ion implantation region and a third ion implantation region on the substrate includes:

performing ion implantation of the first doping type on the active region to form a fifth ion implantation region;

performing ion implantation of the second doping type in the fifth ion implantation region to form a sixth ion implantation region in the fifth ion implantation region, wherein a part of the fifth ion implantation region which is not covered by the sixth ion implantation region serves as the third ion implantation region;

And performing ion implantation of the second doping type in the sixth ion implantation region to form a first ion implantation region in the sixth ion implantation region, wherein a part of the sixth ion implantation region which is not covered by the first ion implantation region serves as the second ion implantation region.

Optionally, the step of fabricating the first isolation region and the second isolation region includes:

and thinning the first isolation region and the second isolation region on the substrate wafer, and manufacturing deep trench isolation which completely penetrates through the substrate to form the first isolation region and the second isolation region.

Optionally, metal connection is performed first, and then the first isolation region and the second isolation region are manufactured.

In addition, in order to achieve the above object, the present invention also provides a photodetector comprising the single photon avalanche diode as described above.

Compared with the prior art, the invention has the beneficial effects that: in order to improve the imaging resolution of the SPAD array chip under the condition that the whole size of the SPAD is not reduced, the single SPAD provided by the embodiment of the invention can be divided into a plurality of sub-SPAD which can be independently used for single photon detection, so that the position sensitive detection of the whole SPAD is realized, and the resolution of the SPAD array is improved. In the embodiment of the invention, the SPAD is divided into the preset equal parts by arranging the second isolation area, so that each sub-area can be used as a sub-SPAD respectively; because the second isolation region may generate carriers in the vicinity thereof due to leakage current and the like to trigger avalanche, so that the dark count rate is increased, by arranging the third doped region with the doping concentration gradually increasing from the upper surface to the lower surface, the region where the lower surface of the first doped region is connected with the side (the side far away from the second isolation region) is more likely to generate avalanche, and the probability of occurrence of avalanche in the region where the lower surface of the first doped region is close to the second isolation region is inhibited, namely, the detection efficiency is improved by utilizing edge breakdown; the second doped region is a doped region with the same doping type as the first doped region but lower doping concentration, and the electric field direction of edge breakdown of the first doped region and the third doped region can be regulated and controlled; that is, unlike the method of suppressing edge breakdown in the conventional SPAD structure, the embodiment of the invention uses edge breakdown to improve the detection efficiency, and obtains SPAD which depends on the edge breakdown operation, so that SPAD can obtain smaller size (the size of sub SPAD is smaller than that of original SPAD) and higher performance, thereby improving the imaging resolution of SPAD array chip and ensuring the detection efficiency without reducing the overall size of SPAD.

Drawings

FIG. 1 is a schematic cross-sectional view of a single photon avalanche diode in accordance with an embodiment of the present invention;

FIG. 2 is a top view of a single photon avalanche diode in accordance with an embodiment of the present invention;

FIG. 3 is a schematic cross-sectional view of another single photon avalanche diode in accordance with an embodiment of the present invention;

FIG. 4 is a schematic cross-sectional view of a single photon avalanche diode in accordance with an embodiment of the present invention;

FIG. 5 is a schematic flow chart of a single photon avalanche diode manufacturing method according to an embodiment of the present invention;

Fig. 6 is a schematic cross-sectional view of another single photon avalanche diode in accordance with an embodiment of the present invention.

Reference numerals illustrate:

1-a first doped region; 2-a second doped region; 3-a third doped region; 4-a fourth doped region; 5-a first isolation region; 6-a second isolation region; 7-a substrate; 8-a fifth doped region; 9-a first ion implantation region; 10-a second ion implantation region; 11-a third ion implantation region; 12-a fourth ion implantation region; 13-eighth ion implantation region.

Detailed Description

In order to make the above objects, features and advantages of the present invention more comprehensible, the following description of the embodiments accompanied with the accompanying drawings will be given in detail. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Fig. 1 is a schematic cross-sectional view of a single photon avalanche diode in accordance with an embodiment of the present invention, and fig. 2 is a top view of a single photon avalanche diode in accordance with an embodiment of the present invention. Referring to fig. 1 and 2, an embodiment of the present invention relates to a single photon avalanche diode comprising a substrate 7 of a first doping type, an active region being electrically isolated in the substrate 7 by a first isolation region 5; the active region is provided with a first doped region 1 and a second doped region 2 of a second doping type, and is also provided with a third doped region 3 and a fourth doped region 4 of a first doping type, the first doping type being opposite to the second doping type, the doping concentration of the first doped region 1 being higher than the second doped region 2, the doping concentration of the fourth doped region 4 being higher than the third doped region 3 (i.e. higher than the maximum doping concentration of the third doped region 3) and the substrate 7, the doping concentration of the third doped region 3 increasing progressively in a direction away from the upper surface of the active region (the upper surface of the active region being the side of the third doped region 3 extending from the surface of the active region to the inside of the active region), the first doped region 1 and the fourth doped region 4 acting as anode contact and cathode contact regions, respectively, according to the doping type.

The third doped region 3 extends from the upper surface of the active region to the inside of the active region, the second doped region 2 extends from the upper surface of the third doped region 3 (the side of the third doped region 3 facing away from the upper surface of the active region is taken as the lower surface, the upper surface is opposite to the lower surface) to the inside of the third doped region 3, the third doped region 3 with the width and the depth being larger than those of the second doped region 2 is surrounded by the third doped region 3, the first doped region 1 extends from the upper surface of the second doped region 2 (the side of the second doped region 2 facing away from the upper surface of the active region is taken as the lower surface, the upper surface is opposite to the lower surface) to the inside of the second doped region 2, the second doped region 2 with the width and the depth being larger than those of the first doped region 1 is surrounded by the fourth doped region 4 along the whole edge of the first isolation region 5, the side of the fourth doped region 4 facing away from the first isolation region 5 is connected with the side of the third doped region 3, which is close to the first isolation region 5;

The substrate 7 is further provided with a second isolation region 6, and the second isolation region 6 divides the first doped region 1, the second doped region 2, the third doped region 3 and the fourth doped region 4 into preset equal parts which are electrically isolated from each other, so that the active region is divided into sub-regions of the preset equal parts, and structures in the sub-regions respectively form a sub-single photon avalanche diode (sub-SPAD).

It should be noted that, in fig. 1 and fig. 2, schematic diagrams are drawn by taking the preset equal parts set to 4 equal parts and the orthographic projection of the active area on the upper surface of the substrate 7 as a rectangle as an example; referring to fig. 2, the front projection of the active region on the upper surface of the substrate 7 is rectangular, and the front projection of the second isolation region 6 on the upper surface of the substrate 7 is cross-shaped, so that the first doped region 1, the second doped region 2, the third doped region 3 and the fourth doped region 4 are all divided into 4 equal parts which are electrically isolated from each other. In a specific embodiment, the preset equal parts may be set as needed, for example, 2 equal parts, 3 equal parts, 4 equal parts, etc., and the shape of the orthographic projection of the second isolation region 6 on the upper surface of the substrate 7 is different according to the different settings of the preset equal parts, for example, when the preset equal parts are set as 2 equal parts, the orthographic projection of the second isolation region 6 on the upper surface of the substrate 7 is an elongated rectangle (which can be regarded as a line if the width is ignored); the shape of the orthographic projection of the active region on the upper surface of the substrate 7 may also be circular or other shape, and is not limited in this embodiment.

In a specific embodiment, the substrate 7 may be a silicon substrate; the first doping type is p-type doping (e.g., boron or boron difluoride doped) and the second doping type is n-type doping (e.g., phosphorus or arsenic doped); or the first doping type is n-type doping and the second doping type is p-type doping. When the first doping type is p-type doping, the first doping region 1 serves as a cathode contact region and the fourth doping region 4 serves as an anode contact region. When the first doping type is n-type doping, the first doping region 1 serves as an anode contact region, and the fourth doping region 4 serves as a cathode contact region.

In a possible implementation, when SPADs are used to make photodetectors, the anode contact areas of each sub SPAD can be connected together, and then the cathode contact areas of each sub SPAD are connected with a set of quenching circuits.

In a possible embodiment, the first doped region 1 may be heavily doped, and the second doped region 2 may be moderately doped, so that the doping concentration of the first doped region 1 is higher than that of the second doped region 2; the fourth doped region 4 may be heavily doped and the third doped region 3 and the substrate 7 may be moderately doped such that the doping concentration of the fourth doped region 4 is higher than the doping concentration of the third doped region 3 and the substrate 7; the third doped region 3 may be doped such that the doping concentration increases gradually in a direction away from the upper surface of the active region by retrograde doping.

The embodiment of the present invention mainly describes a single photon avalanche diode, it can be understood that more than one single photon avalanche diode may be integrated on the same substrate 7, and other devices may also be formed, where the devices are isolated by an isolation region, and in this embodiment, the isolation region for isolating the single photon avalanche diode from other devices is referred to as a first isolation region 5, and the isolation region for isolating the sub single photon avalanche diode in the single photon avalanche diode is referred to as a second isolation region 6. The isolation region may be implemented using any isolation structure capable of electrically isolating the isolated portions, for example, deep trench isolation that extends entirely through the depth of the substrate 7.

In order to improve the imaging resolution of the SPAD array chip under the condition that the whole size of the SPAD is not reduced, the single SPAD provided by the embodiment of the invention can be divided into a plurality of sub-SPAD which can be independently used for single photon detection, so that the position sensitive detection of the whole SPAD is realized, and the resolution of the SPAD array is improved. In the embodiment of the invention, the SPAD is divided into the preset equal parts by arranging the second isolation region 6, so that each sub-region can be used as a sub-SPAD respectively; since the second isolation region 6 may generate carriers in the vicinity thereof due to leakage current and the like to trigger avalanche, resulting in an increase in dark count rate, the embodiment of the present invention, by providing the third doped region 3 with a doping concentration gradually increasing from the upper surface to the lower surface, makes the region where the lower surface of the first doped region 1 meets the side (the side far from the second isolation region 6) more prone to avalanche, and suppresses the probability of avalanche occurring in the region where the lower surface of the first doped region 1 is close to the second isolation region 6, that is, improves the detection efficiency by using edge breakdown; the second doped region 2 is a doped region with the same doping type as the first doped region 1 but lower doping concentration, and the electric field direction of the edge breakdown of the first doped region 1 and the third doped region 3 can be regulated and controlled; that is, unlike the method of suppressing edge breakdown in the conventional SPAD structure, the embodiment of the present invention uses edge breakdown to improve the detection efficiency, and obtains SPAD that relies on edge breakdown to enable SPAD to obtain smaller size (the size of sub SPAD is smaller than that of the original SPAD) and higher performance. It can be appreciated that, since each sub SPAD can independently detect an incident photon, the position sensitive detection of the entire SPAD is realized, so that the SPAD array resolution is improved by a preset equal number, for example, the preset equal number is 4, and the SPAD array resolution is improved by a factor of 4.

Fig. 3 is a schematic cross-sectional view of a single photon avalanche diode in accordance with another embodiment of the present invention. Referring to fig. 3, a single photon avalanche diode according to another embodiment is different from the single photon avalanche diode shown in fig. 1 mainly in that a fifth doped region 8 of the first doping type is further disposed in the active region, the depth of the fourth doped region 4 is smaller than the depth of the third doped region 3, the doping concentration of the fifth doped region 8 is smaller than the doping concentration of the fourth doped region 4, the fifth doped region 8 extends from the upper surface of the fourth doped region 4 to the lower surface of the active region along the full edge of the first isolation region 5, a portion of the fifth doped region 8 facing away from the first isolation region 5 is connected with the third doped region 3, and the depth of the fifth doped region 8 is larger than the depth of the third doped region 3.

In this embodiment, taking the first doping type as p-type doping as an example, the fifth doped region 8 is used to guide the anode potential of the SPAD to the bottom of the substrate 7, so as to further ensure that the electric field direction faces the edge breakdown region of the first doped region 1, thereby further improving the detection efficiency of the SPAD. The fifth doped region 8 can also prevent the dark count rate from being increased due to the non-photogenerated carriers generated near the first isolation region 5 entering the avalanche region.

The embodiment of the invention also relates to a manufacturing method of the single photon avalanche diode, which can be used for manufacturing the single photon avalanche diode described in the embodiment. It should be appreciated that the fabrication of the single photon avalanche diode described in the above embodiments is not limited to the method described below.

Fig. 4 is a schematic cross-sectional view of a single photon avalanche diode in accordance with one embodiment of the present invention. Fig. 5 is a flow chart of a method for manufacturing a single photon avalanche diode according to an embodiment of the present invention. Referring to fig. 1 to 5, in an embodiment of the present invention, a method for fabricating a single photon avalanche diode includes the following steps:

Step S1: providing a substrate 7, and defining an active region on the substrate 7;

Step S2: performing ion implantation in the active region, forming a first ion implantation region 9, a second ion implantation region 10, a third ion implantation region 11 and a fourth ion implantation region 12 on the substrate 7, wherein the first ion implantation region 9 extends from the upper surface of the active region to the inside of the active region, the second ion implantation region 10 extends from the upper surface of the third ion implantation region 11 to the inside of the third ion implantation region 11, is surrounded by the third ion implantation region 11 with a width and a depth both greater than those of the second ion implantation region 10, the first ion implantation region 9 extends from the upper surface of the second ion implantation region 10 to the inside of the second ion implantation region 10, is surrounded by the second ion implantation region 10 with a width and a depth both greater than those of the first ion implantation region 9, the fourth ion implantation region 12 extends from the upper surface of the active region to the inside of the active region along one side of the third ion implantation region 11, and the fourth ion implantation region 12 reaches the edge of the active region on one side of the fourth ion implantation region 12 facing away from the third ion implantation region 11;

step S3: a first isolation region 5 is manufactured on the substrate 7 along the outer edge of the active region, a second isolation region 6 is manufactured on the substrate 7, the second isolation region 6 electrically isolates the first ion implantation region 9, the second ion implantation region 10, the third ion implantation region 11 and the fourth ion implantation region 12 from a preset equal part, and the first ion implantation region 9, the second ion implantation region 10, the third ion implantation region 11 and the fourth ion implantation region 12 isolated by the second isolation region 6 are respectively used as a first doped region 1, a second doped region 2, a third doped region 3 and a fourth doped region 4.

In step S2, the doping type of the first ion implantation region 9 and the second ion implantation region 10 is the second doping type, and the doping type of the third ion implantation region 11 and the fourth ion implantation region 12 is the first doping type. The first ion implantation region 9 is implanted with ions having a higher doping concentration than the second ion implantation region 10. The doping concentration of the ions implanted in the fourth ion implantation region 12 is higher than the maximum doping concentration of the ions implanted in the third ion implantation region 11 and higher than the doping concentration of the substrate 7. The third ion implantation region 11 may be implanted in a back-doping manner such that the doping concentration of the fourth ion implantation region 12 gradually increases in a direction away from the upper surface of the active region.

In a possible embodiment, in step S3, in the process of manufacturing the first isolation region 5 and the second isolation region 6, thinning may be performed in the manufacturing region of the first isolation region 5 and the second isolation region 6 (the region where the first isolation region 5 and the second isolation region 6 need to be manufactured) on the wafer of the substrate 7, and then deep trench isolation is manufactured to completely penetrate through the substrate 7 to form the first isolation region 5 and the second isolation region 6. By first thinning the wafer, penetration of the substrate 7 can be enabled when making deep trench isolation.

In a possible embodiment, in step S2, when ion implantation is performed in the active region and the first ion implantation region 9, the second ion implantation region 10 and the third ion implantation region 11 are formed on the substrate 7, ion implantation of the first doping type may be performed first in the active region to form a fifth ion implantation region (the region where the three regions of the first ion implantation region 9, the second ion implantation region 10 and the third ion implantation region 11 are combined in fig. 4 is not marked with a reference numeral); performing ion implantation of the second doping type in the fifth ion implantation region to form a sixth ion implantation region (the region formed by combining the first ion implantation region 9 and the second ion implantation region 10 in fig. 4 is not marked by a reference numeral) in the fifth ion implantation region, wherein the part of the fifth ion implantation region, which is not covered by the sixth ion implantation region, is used as a third ion implantation region 11, and the depth and the width of the fifth ion implantation region are larger than those of the sixth ion implantation region; and then carrying out ion implantation of the second doping type in the sixth ion implantation region to form a first ion implantation region 9 in the sixth ion implantation region, wherein the part of the sixth ion implantation region which is not covered by the first ion implantation region 9 is used as a second ion implantation region 10, and the width and the depth of the sixth ion implantation region are larger than those of the first ion implantation region 9.

Fig. 6 is a schematic cross-sectional view of a single photon avalanche diode in accordance with one embodiment of the present invention. In a possible embodiment, referring to fig. 6, in step S2, ion implantation is performed in the active region, before forming the fourth ion implantation region 12 on the substrate 7, ion implantation may be performed in the active region to form a seventh ion implantation region (a region where the fourth ion implantation region 12 and the eighth ion implantation region 13 are combined in fig. 6, and reference numerals are not used), the seventh ion implantation region extends from the upper surface of the active region to the inside of the active region along the entire edge of the side of the third ion implantation region 11 facing away from the second ion implantation region 10, and the side of the seventh ion implantation region facing away from the third ion implantation region 11 reaches the edge of the active region, and the depth of the seventh ion implantation region is greater than the depth of the third ion implantation region 11. And then implanting a fourth ion implantation region 12 into the seventh ion implantation region, wherein the width of the fourth ion implantation region 12 is the same as that of the seventh ion implantation region, the depth is lower than that of the seventh ion implantation region, the part of the seventh ion implantation region which is not covered by the fourth ion implantation region 12 is used as an eighth ion implantation region 13, and after the second isolation region 6 is manufactured, the eighth ion implantation region 13 isolated by the second isolation region 6 is used as a fifth doped region 8.

In one possible embodiment, in step S3, the metal connection may be first formed, and then the first isolation region 5 and the second isolation region 6 may be manufactured without damaging the metal connection. The metal wire is used for connecting the single photon avalanche diode with other devices needing to be connected, such as a quenching circuit, a reading circuit and the like.

On the basis of the embodiment, the embodiment of the invention also provides a photoelectric detector, which comprises any one of the single photon avalanche diodes.

It should be noted that, in the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different manner from other embodiments, and identical and similar parts between the embodiments are referred to each other. For the method disclosed in the embodiment, the description is relatively simple because of corresponding to the structure disclosed in the embodiment, and the relevant points are only referred to the description of the structural parts.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The foregoing embodiment numbers of the present invention are merely for the purpose of description, and do not represent the advantages or disadvantages of the embodiments.

The foregoing description is only of the preferred embodiments of the present invention, and is not intended to limit the scope of the invention, but rather is intended to cover any equivalents of the structures or equivalent processes disclosed herein or in the alternative, which may be employed directly or indirectly in other related arts.

Claims (10)

1. A single photon avalanche diode, comprising:

A substrate of a first doping type, wherein an active region is electrically isolated from a first isolation region in the substrate;

The active region is provided with a first doping region and a second doping region with a second doping type, and is also provided with a third doping region and a fourth doping region with the first doping type, the first doping type is opposite to the second doping type, the doping concentration of the first doping region is higher than that of the second doping region, the doping concentration of the fourth doping region is higher than that of the third doping region and the substrate, the doping concentration of the third doping region is gradually increased along the direction away from the upper surface of the active region, and the first doping region and the fourth doping region are respectively used as an anode contact region and a cathode contact region according to the doping type;

The third doped region extends from the upper surface of the active region to the inside of the active region, the second doped region extends from the upper surface of the third doped region to the inside of the third doped region, the third doped region is surrounded by the third doped region with the width and the depth being larger than those of the second doped region, the first doped region extends from the upper surface of the second doped region to the inside of the second doped region, the second doped region with the width and the depth being larger than those of the first doped region, the fourth doped region extends from the upper surface of the active region to the inside of the active region along the whole edge of the first isolation region, and one side of the fourth doped region, which is far away from the first isolation region, is connected with one side of the third doped region, which is close to the first isolation region;

And a second isolation region is further arranged in the substrate, the second isolation region divides the first doped region, the second doped region, the third doped region and the fourth doped region into preset equal parts which are electrically isolated from each other, so that the active region is divided into sub-regions of the preset equal parts, and structures in the sub-regions respectively form a sub-single photon avalanche diode.

2. The single photon avalanche diode according to claim 1, wherein a depth of said fourth doped region is less than a depth of said third doped region, a fifth doped region of said first doping type is further provided in said active region, a doping concentration of said fifth doped region is less than a doping concentration of said fourth doped region, said fifth doped region extends from an upper surface of said fourth doped region to a lower surface of said active region along a full edge of said first doped region, a portion of said fifth doped region facing away from said first doped region meets said third doped region, and a depth of said fifth doped region is greater than a depth of said third doped region.

3. The single photon avalanche diode according to claim 1, wherein said first isolation region and said second isolation region are isolation regions formed by deep trench isolation.

4. The single photon avalanche diode according to claim 1, wherein the orthographic projection of said active region on said upper surface of said substrate is rectangular, and wherein the orthographic projection of said second isolation region on said upper surface of said substrate is cross-shaped to divide said first doped region, said second doped region, said third doped region and said fourth doped region into 4 equal parts electrically isolated from each other.

5. The single photon avalanche diode according to any one of claims 1 to 4, wherein said first doping type is p-type doping and said second doping type is n-type doping.

6. A method of making a single photon avalanche diode according to any one of claims 1 to 5, comprising:

providing the substrate, and demarcating the active area on the substrate;

Performing ion implantation in the active region, and forming a first ion implantation region, a second ion implantation region, a third ion implantation region and a fourth ion implantation region on the substrate, wherein the first ion implantation region extends from the upper surface of the active region to the inside of the active region, the second ion implantation region extends from the upper surface of the third ion implantation region to the inside of the third ion implantation region, is surrounded by the third ion implantation region with the width and the depth being larger than those of the second ion implantation region, the first ion implantation region extends from the upper surface of the second ion implantation region to the inside of the second ion implantation region, is surrounded by the second ion implantation region with the width and the depth being larger than those of the first ion implantation region, the fourth ion implantation region extends from the upper surface of the active region to the inside of the active region along one side of the third ion implantation region facing away from the second ion implantation region, and reaches the edge of the active region on one side of the fourth ion implantation region facing away from the third ion implantation region;

And manufacturing a first isolation region on the substrate along the outer edge of the active region, manufacturing a second isolation region on the substrate, wherein the second isolation region electrically isolates the first ion implantation region, the second ion implantation region, the third ion implantation region and the fourth ion implantation region from preset equal parts, and the first ion implantation region, the second ion implantation region, the third ion implantation region and the fourth ion implantation region which are isolated by the second isolation region are respectively used as the first doping region, the second doping region, the third doping region and the fourth doping region.

7. The method of fabricating a single photon avalanche diode according to claim 6, wherein the step of performing ion implantation in said active region to form a first ion implantation region, a second ion implantation region and a third ion implantation region on said substrate comprises:

performing ion implantation of the first doping type on the active region to form a fifth ion implantation region;

performing ion implantation of the second doping type in the fifth ion implantation region to form a sixth ion implantation region in the fifth ion implantation region, wherein a part of the fifth ion implantation region which is not covered by the sixth ion implantation region serves as the third ion implantation region;

And performing ion implantation of the second doping type in the sixth ion implantation region to form a first ion implantation region in the sixth ion implantation region, wherein a part of the sixth ion implantation region which is not covered by the first ion implantation region serves as the second ion implantation region.

8. The method of fabricating a single photon avalanche diode according to claim 6, wherein said step of fabricating said first isolation region and said second isolation region comprises:

and thinning the first isolation region and the second isolation region on the substrate wafer, and manufacturing deep trench isolation which completely penetrates through the substrate to form the first isolation region and the second isolation region.

9. The method of claim 6, wherein metal wiring is performed before the first isolation region and the second isolation region are fabricated.

10. A photodetector comprising a single photon avalanche diode according to any one of claims 1 to 5.