Single photon avalanche diode structure and manufacturing method thereof

Abstract

The present invention relates to a single photon avalanche diode (SPAD) structure and a method for manufacturing the same, and more particularly, to a method for forming a guide wall on the side of a first impurity-doped region and a second impurity-doped region so as to induce photo-generated charges to an avalanche region on the side of a PN junction region between the first impurity-doped region and the second impurity-doped region; a) diffusion is carried out, and thus the photon detection efficiency (Photon Detection Efficiency; a single photon avalanche diode (SPAD) structure of a single photon avalanche diode (PED) and a method of manufacturing

Description

Technical Field

[0001] The present invention relates to a single-photon avalanche diode (SPAD) structure and a manufacturing method thereof, and in particular to a single-photon avalanche diode (SPAD) structure and a manufacturing method thereof, in which guide walls are formed on the sides of a first impurity-doped region and a second impurity-doped region, thereby inducing photogenerated charges to diffuse toward an avalanche region (Avalanche Region; A) on the side of a PN junction region between the first impurity-doped region and the second impurity-doped region, thereby improving the photon detection efficiency (PED). Background Art

[0002] Generally speaking, a single photon avalanche diode (SPAD) is used as a pixel photoelectric conversion element of an imaging device. The single photon avalanche diode (SPAD) as described above has a PN junction region for detecting incident radiation and operates in Geiger mode, that is, a mode of operation at a voltage much higher than the breakdown voltage of the single photon avalanche diode, which is also called the avalanche voltage. Because a voltage exceeding the breakdown voltage is loaded in the single photon avalanche diode (SPAD), electron avalanche caused by carriers generated by photoelectric conversion will occur, and the single photon avalanche diode (SPAD) is in a breakdown state. As a result, amplification of carriers based on photoelectric conversion occurs, thereby achieving an improvement in sensitivity in the imaging device.

[0003] Figure 1 This is a cross-sectional view for explaining the structure of a conventional single-photon avalanche diode (SPAD).

[0004] See Figure 1, a substrate 910 having a front side 911 and a back side 913 is formed on the existing single-photon avalanche diode (SPAD) structure 9. In addition, a structure in which a P-type region 930 is stacked on an N-type region 950 can be formed in the substrate 910. A PN junction region can be formed by the P-type region 930 and the N-type region 950 as described above. In the structure 9 described above, when a reverse voltage of a degree that can achieve avalanche breakdown is loaded to the PN junction region, the electrons generated by the single photon will reach the avalanche region A and generate a large current pulse (Pulse), so that the single photon can be measured. Generally speaking, in the single-photon avalanche diode (SPAD) structure 9, the photon detection efficiency (PDE) is derived from the ratio of the number of photons reaching the pixel to the number of current pulses generated by the photogenerated electrons. Therefore, in order to obtain a higher photon detection efficiency (PDE), it is necessary to make the photogenerated electrons reach the avalanche region A as much as possible.

[0005] In the conventional single-photon avalanche diode (SPAD) structure 9 described above, a significant portion of the photogenerated electrons diffuse to the sides of the PN junction region rather than the avalanche region A, preventing them from contributing to photon detection. In particular, electrons generated on the sides of the P-type region 930 and the N-type region 950 do not pass through the avalanche region A but instead flow through the shortest distance, namely, to the sides of the PN junction region PN, to the cathode.

[0006] In order to solve the above-mentioned problems, the inventors of the present invention propose a novel single-photon avalanche diode (SPAD) structure with an improved structure and a manufacturing method thereof, which will be described in detail in the subsequent content.

[0007] Prior art literature

[0008] Patent Literature

[0009] Korean Patent Publication No. 10-2019-0049598, "Single Photon Avalanche Diode (SPAD) Image Sensor and Related Manufacturing Method" Summary of the Invention

[0010] The present invention is proposed to solve the problems existing in the prior art as described above.

[0011] The object of the present invention is to provide a single photon avalanche diode (SPAD) structure and a manufacturing method thereof, in which guide walls are formed on the sides of a first impurity-doped region and a second impurity-doped region, thereby inducing photogenerated charges to diffuse toward an avalanche region on the side of a PN junction region between the first impurity-doped region and the second impurity-doped region, thereby improving the photon detection efficiency (PED).

[0012] In addition, the present invention aims to provide a single photon avalanche diode (SPAD) structure and a manufacturing method thereof, which does not form a gap between the first region and the second region, thereby preventing photogenerated charges on the side of the substrate from diffusing to the side of the PN junction region.

[0013] In addition, the present invention aims to provide a single photon avalanche diode (SPAD) structure and a manufacturing method thereof, in which the second region is doped with impurities at a lower concentration than the first region, thereby diffusing photogenerated charges on the substrate side into the avalanche region.

[0014] In addition, an object of the present invention is to provide a single photon avalanche diode (SPAD) structure and a manufacturing method thereof, in which a guard ring is formed between a first region and a first impurity-doped region and a second impurity-doped region to reduce a dark count rate.

[0015] In addition, an object of the present invention is to provide a single photon avalanche diode (SPAD) structure and a manufacturing method thereof, in which the second region is in contact with the second impurity-doped region, so that photogenerated charges diffuse into the avalanche region.

[0016] In addition, the object of the present invention is to provide a single-photon avalanche diode (SPAD) structure and a manufacturing method thereof, in which a first conductive type impurity-doped region, i.e., a second region, and a first conductive type impurity-doped region, i.e., a second impurity-doped region, having a lower concentration than the second region, are stacked, thereby preventing the second impurity-doped region from being misaligned with the first impurity-doped region.

[0017] In order to achieve the above-mentioned objects, the present invention can be implemented through embodiments having the following configurations.

[0018] In one embodiment of the present invention, the single-photon avalanche diode (SPAD) structure according to the present invention is characterized in that it includes: a substrate having a front side and a back side; a first impurity-doped region located on the front side of the substrate within the substrate; a second impurity-doped region located on the first impurity-doped region within the substrate; and a guide wall surrounding the side walls of the first impurity-doped region and the second impurity-doped region within the substrate.

[0019] In another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that the guide wall is a first conductivity type impurity doped region, and the first impurity doped region is a second conductivity type impurity doped region.

[0020] In another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that the guide wall includes: a first region extending upward from the front side to the back side of the substrate.

[0021] In another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that the upper side surface of the first region in the substrate is located at a higher position than the upper side surface of the second impurity-doped region.

[0022] In another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that the guide wall further includes a second region extending on the first region toward an upper side surface of an adjacent second impurity-doped region.

[0023] In yet another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that the second region is in contact with the second impurity-doped region.

[0024] In yet another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that the second region is formed in a manner of having an open opening in which at least a portion of an upper side surface of the second impurity-doped region is open.

[0025] In yet another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that the second region is a region doped with first conductivity type impurities at a lower concentration than that of the first region.

[0026] In another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that it also includes a first contact region, which is located in the first impurity-doped region on the front side of the substrate; and a second contact region, which is separated from the first contact region on the front side of the substrate.

[0027] In another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that it further includes a guard ring located between the guide wall and the adjacent first impurity-doped region and the second impurity-doped region.

[0028] In yet another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that the guard ring is a region doped with first conductivity type impurities at a lower concentration than the first region and the second region.

[0029] In another embodiment of the present invention, the single-photon avalanche diode (SPAD) structure according to the present invention is characterized in that it includes: a substrate having a front side and a back side; an isolation region located on one side of a unit pixel boundary; a first impurity-doped region located on the front side of the substrate within the substrate; a second impurity-doped region located on the first impurity-doped region within the substrate; a first contact region located within the first impurity-doped region; a second contact region located between the front side of the substrate and the isolation region; and a guide wall surrounding the side walls of the first impurity-doped region and the second impurity-doped region within the substrate, the guide wall including: a first region located on the second contact region; and a second region extended on the first region in a manner that contacts the side walls of the adjacent second impurity-doped region.

[0030] In another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that the first region is a first conductivity type impurity doped region with a lower concentration than the second contact region and a higher concentration than the second region.

[0031] In yet another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that the first impurity doping concentration gradually decreases toward the second contact region, the first region, and the second region.

[0032] In another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that the upper side surface of the second region is located higher than the upper side surface of the contacted second impurity-doped region.

[0033] In yet another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that the first region is spaced apart from a sidewall of an adjacent first impurity-doped region.

[0034] In yet another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that the guide wall is an impurity-doped region of a type opposite to that of the first impurity-doped region.

[0035] In another embodiment of the present invention, the single-photon avalanche diode (SPAD) structure according to the present invention is characterized in that it includes: a substrate having a front side and a back side; a first impurity-doped region located in the substrate on the front side of the substrate; a guide wall including a first region separated from the first impurity-doped region in the substrate, and a second region crossing the unit pixel on the first region; and a second impurity-doped region located in the second region, the second impurity-doped region being a first conductive type impurity-doped region with a lower concentration than the second region.

[0036] In another embodiment of the present invention, the single photon avalanche diode (SPAD) structure according to the present invention is characterized in that the second impurity-doped region is formed by implanting second conductive type impurities into the second region after forming the second region.

[0037] With the above-described configuration, the present invention can achieve the following effects.

[0038] The present invention has the effect of forming guide walls on the sides of the first impurity-doped region and the second impurity-doped region, thereby inducing photogenerated charges to diffuse toward the avalanche region on the side of the PN junction region between the first impurity-doped region and the second impurity-doped region, thereby improving the photon detection efficiency (PED).

[0039] Furthermore, the present invention has the effect of preventing a gap from being formed between the first region and the second region, thereby preventing photogenerated charges on the side of the substrate from diffusing to the side of the PN junction region.

[0040] Furthermore, the present invention has the effect of causing the second region to be doped with impurities at a lower concentration than the first region, thereby diffusing photogenerated charges on the side of the substrate into the avalanche region.

[0041] In addition, the present invention has the effect of forming a guard ring between the first region and the first impurity-doped region and the second impurity-doped region, thereby reducing the dark count rate.

[0042] Furthermore, the present invention has the effect of making the second region contact the second impurity-doped region, thereby causing photogenerated charges to diffuse into the avalanche region.

[0043] In addition, the present invention has the effect of stacking a first conductive type impurity doped region, i.e., a second region, and a first conductive type impurity doped region, i.e., a second impurity doped region, having a lower concentration than the second region, thereby preventing the second impurity doped region from being misaligned with the first impurity doped region.

[0044] It should also be noted that even if the effects are not explicitly mentioned herein, as long as they can be achieved through the technical features of the present invention and are described in the following description and their potential effects, they should be understood as being described in the description of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a cross-sectional view for explaining the structure of a conventional single-photon avalanche diode (SPAD).

[0046] Figure 2 FIG. 1 is a cross-sectional view illustrating the structure of a single-photon avalanche diode (SPAD) according to a first embodiment of the present invention.

[0047] Figure 3 is a cross-sectional view for illustrating the structure of a single-photon avalanche diode (SPAD) according to a second embodiment of the present invention.

[0048] Figure 4 is a cross-sectional view for illustrating the structure of a single-photon avalanche diode (SPAD) according to a third embodiment of the present invention.

[0049] Figure 5 is a cross-sectional view for illustrating the structure of a single-photon avalanche diode (SPAD) according to a fourth embodiment of the present invention.

[0050] Figures 6 to 11 It is a cross-sectional view for explaining a method for manufacturing a single photon avalanche diode (SPAD) structure according to one embodiment of the present invention.

[0051] Explanation of symbols

[0052] 1: Single-photon avalanche diode structure, 110: Substrate, 111: Front side, 113: Back side, 120: First impurity-doped region, 121: First contact region, 130: Second impurity-doped region, 140: Second contact region, 150: Isolation region, 160: Guide wall, 161: First region, 163: Second region, 170: Guard ring, 181: First metal contact region, 183: Second metal contact region, 185: First metal wiring, 187: Second metal wiring, 191: Planarization layer, 193: Microlens, A: Avalanche region, A1: Depletion region, O: Open port, C: Carrier. DETAILED DESCRIPTION

[0053] Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. The embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as limited to the following embodiments. Instead, it should be interpreted based on the scope of the claims. Furthermore, the following embodiments are provided solely for the purpose of more fully explaining the present invention to those with average knowledge in the field and are provided as a reference.

[0054] Unless otherwise specified in the context, the singular form used in this specification may also include the plural form. In addition, the words "comprise" and / or "comprising" used in this specification are only used to indicate that the mentioned shapes, numbers, steps, actions, components, elements and / or combinations exist, and do not exclude the possibility that one or more other shapes, numbers, actions, components, elements and / or combinations exist or are added.

[0055] In the following description, when a component (or layer) is described as being disposed on another component (or layer), it may be described as either being disposed directly on another component or as being disposed between the corresponding components. In addition, when a component is described as being disposed directly on or above another component, there is no other component between the corresponding components. In addition, the terms "above," "upper," "lower," "upper side," "lower side," or "side" of a component indicate their relative positional relationship.

[0056] Furthermore, in order to describe various items such as various elements, regions and / or parts, terms such as first and second may be used, but the second configuration is not necessarily a prerequisite for the first configuration.

[0057] In addition, the conductivity type of a component or a doped region can be specified as "P-type" or "N-type" based on the main carrier characteristics, but this is only for the convenience of explanation, and the technical concept of the present invention is not limited by the example. For example, "P-type" or "N-type" in the following content can also use the more general term "first conductivity type" or "second conductivity type". In the following content, the first conductivity type can represent P-type and the second conductivity type can represent N-type, or conversely, the first conductivity type can represent N-type and the second conductivity type can represent P-type.

[0058] Furthermore, “high concentration” and “low concentration” indicating the doping concentration of an impurity region should be understood as the relative doping concentration of one component to another component.

[0059] Next, a single-photon avalanche diode (SPAD) structure 1 according to the present invention will be described in detail with reference to the accompanying drawings. The single-photon avalanche diode structure 1 according to the present invention is preferably a single-photon avalanche diode (SPAD) structure in a back-illuminated image sensor, but the scope of the present invention is not limited thereto.

[0060] The present invention relates to a single-photon avalanche diode (SPAD) structure, and more particularly to a single-photon avalanche diode (SPAD) structure in which guide walls are formed on the sides of a first impurity-doped region and a second impurity-doped region, thereby inducing photogenerated charges to diffuse toward an avalanche region (Avalanche Region; A) on the side of a PN junction region between the first impurity-doped region and the second impurity-doped region, thereby improving the photon detection efficiency (PED).

[0061] Figure 2 FIG. 1 is a cross-sectional view illustrating the structure of a single-photon avalanche diode (SPAD) according to a first embodiment of the present invention.

[0062] First, the single photon avalanche diode structure 1 according to the first embodiment of the present invention will be described in detail.

[0063] See Figure 2 The single photon avalanche diode structure 1 according to the first embodiment of the present invention comprises a substrate 110 having a front surface 111 and a back surface 113. The substrate 110 is a low-concentration doped region of the first conductive type impurities and can be formed by epitaxial growth.

[0064] In addition, a first impurity-doped region 120 may be formed on the front surface 111 of the substrate 110. The first impurity-doped region 120 may be a low-concentration doped region of the second conductive type formed on the surface of the substrate 110. The first impurity-doped region 120 forms a PN junction region with the second impurity-doped region 130 on its upper side, and the region between the two regions (the first impurity-doped region 120 and the second impurity-doped region 130) may become an avalanche amplification region, i.e., an avalanche region A. The term "avalanche region A" refers to the depletion region A1 (see Figure 1 ) can be formed on the interface side between the first impurity-doped region 120 and the second impurity-doped region 130.

[0065] In addition, a first contact region 121 can be formed in the first impurity-doped region 120. That is, the first contact region 121 can be formed in a manner surrounded by the first impurity-doped region 120. The first contact region 121 as described above is a second conductive type impurity-doped region, preferably an impurity-doped region with a higher concentration than the first impurity-doped region 120. The first contact region 121 can be electrically or physically connected to the first metal contact region 181 on the front surface 111 of the substrate 110. The first contact region 121 can be formed on one side of the surface of the front surface 111 of the substrate 110, but the scope of the present invention is not limited thereto. The first contact region 121 as described above can be electrically connected to the cathode electrode (first metal contact region 181, first metal wiring 185).

[0066] Furthermore, a second impurity-doped region 130 can be formed on the first impurity-doped region 120 within the substrate. A PN junction region can be formed by the second impurity-doped region 130 and the first impurity-doped region 120. The second impurity-doped region 130 is a first conductivity type impurity-doped region, preferably doped with impurities at a higher concentration than the substrate 110 and at a lower concentration than the guide wall 160 described later.

[0067] In addition, a second contact region 140 can be formed on the side of the front surface 111 of the substrate 110, separated from the first impurity-doped region 120. The second contact region 140 can be formed in a manner that is separated from the first impurity-doped region 120 and surrounds the side of the first impurity-doped region 120 at a certain height. That is, as an example of the second contact region 140, it can be formed in a disk shape, but the scope of the present invention is not limited to this. In the illustrated cross-sectional view, the second contact region 140 can be formed on the left and right sides of the first contact region 121, separated from the first contact region 121. The second contact region 140 described above is a first conductive type impurity-doped region, and it is preferably doped with a higher concentration of first conductive type impurities than the guide wall 160 described later. In addition, the second contact region 140 can be electrically or physically connected to the second metal contact region 183 on the front surface 111 of the substrate 110. The second contact region 140 can be electrically connected to the cathode electrode (second metal contact region 183, second metal wiring 187).

[0068] Next, an isolation region 150 may be formed on one side of the unit pixel boundary. As an example, the isolation region 150 may extend vertically from the back surface 113 of the substrate 110 to the second contact region 140 or the front surface 111. The isolation region 150 may be, for example, a first conductivity type impurity doped region.

[0069] Furthermore, a sidewall structure, or guide wall 160, may be formed within the substrate 110, spaced from the sidewalls of the first impurity-doped region 120 and the second impurity-doped region 130. The guide wall 160, as described above, is a first-conductivity-type impurity-doped region that prevents charge from diffusing toward the sides of the PN junction region between the first impurity-doped region 120 and the second impurity-doped region 130 while simultaneously guiding the charge toward the avalanche region A. In this case, the guide wall 160 should be doped with impurities of the opposite type as those of the first impurity-doped region 120. Furthermore, the guide wall 160 may include a first region 161 and a second region 163.

[0070] The first region 161 is an impurity-doped region extending to a predetermined depth from the front surface 111 of the substrate 110 toward the back surface 113. The first region 161 is preferably doped with first conductivity-type impurities at a higher concentration than the second impurity-doped region 130 and at a lower concentration than the second contact region 140.

[0071] By adopting the above-described structure, the charge generated between the first region 161 and the isolation region 150 can be easily moved to the side of the second region 163 described later. In addition, the upper side surface of the first region 161 can be extended to a position higher than the upper side surface of the second impurity-doped region 130 (or a position adjacent to the back surface 113 of the substrate 110) or formed at substantially the same height. The first region 161 can be formed in a ring shape that surrounds the side walls of the first impurity-doped region 120 and the second impurity-doped region 130, but the scope of the present invention is not limited thereto. At this time, it is preferable that the first region 161 is formed in a manner that is separated from the adjacent first impurity-doped region 120 and the second impurity-doped region 130 in the lateral direction.

[0072] The second region 163 is formed by extending a certain length inward from the first region 161 within the substrate 110 (or toward the upper side of the second impurity-doped region 130). The bottom surface of the second region 163 can be in contact with the upper side of the second impurity-doped region 130 or separated by a certain length, but the former is preferred. In addition, the second region 163 can be formed in a ring shape, for example, and preferably has an opening O on the upper side of the second impurity-doped region 130 within the substrate 110. The opening O can guide the diffusion of charges toward the avalanche region A.

[0073] In addition, the second region 163 is preferably a region with a low concentration of first conductive type impurities compared to the first region 161. In this way, the charges formed between the guide wall 160 and the adjacent isolation region 150 can be induced to move more easily toward the side of the open port O. Specifically, it is preferable that the doping concentration of the first conductive type impurities gradually decreases toward the second impurity-doped region 130, the first region 161, and the second region 163. Alternatively, the first region 161 and the second region 163 may have substantially the same first impurity doping concentration. In addition, it is preferable that the second region 163 and the adjacent first region 161 are physically connected to each other, but the scope of the present invention is not limited to this.

[0074] At this time, a guard ring 170 may be formed between the first region 161 and the adjacent first impurity-doped region 120 and the second impurity-doped region 130. The guard ring 170 is used to reduce the dark count rate (DCR) and preferably has substantially the same first impurity doping concentration as the substrate 110.

[0075] As an example, an insulating film layer OX, such as an oxide film layer, is formed on the front surface 111 of the substrate 110. A first metal contact region 181 connected to the first contact region 121 and a first metal wiring 185 electrically or physically connected to the first metal contact region 181 may be formed within the insulating film layer OX. As an example, the first metal wiring 185 may be a metal layer such as aluminum (Al), and may function as a reflector that reflects light incident from the back surface 113 of the substrate 110 and improves the light path. Furthermore, a second metal contact region 183 connected to the second contact region 140 and a second metal wiring 187 electrically or physically connected to the second metal contact region 183 may be formed within the insulating film layer OX.

[0076] In addition, a planarization layer 191 may be formed on the back surface 113 of the substrate 110 , and a microlens 193 may be formed on the planarization layer 191 .

[0077] Figure 3 is a cross-sectional view for illustrating the structure of a single-photon avalanche diode (SPAD) according to a second embodiment of the present invention.

[0078] Next, a single-photon avalanche diode structure 2 according to a second embodiment of the present invention will be described in detail. This single-photon avalanche diode structure 2 can be formed in substantially the same manner as the single-photon avalanche diode structure 1 according to the first embodiment, except for the guide wall 260. Therefore, only the guide wall 260 will be described in detail. Furthermore, for components identical to the first embodiment, the first digit of the figure number of the first embodiment has been changed from "1" to "2."

[0079] See Figure 3 The single-photon avalanche diode structure 2 according to the second embodiment is characterized in that the second region 163 according to the first embodiment is not formed. That is, in the second embodiment, the guide wall 260 only includes the first region 261. The first region 261 as described above extends to a certain depth from the front side 211 of the substrate 210 to the back side 213 side of the substrate 210. At this time, it is preferable that the upper side surface of the first region 261 extends to a position higher than the upper side surface of the adjacent second impurity-doped region 230 (or a position adjacent to the back side 213 of the substrate 210). Through the above-mentioned structure, for example, it is possible to prevent the charges generated between the guide wall 260 and the isolation region 250 from moving to the side of the PN junction region formed by the first impurity-doped region 220 and the second impurity-doped region 230 to the greatest extent.

[0080] The guide wall 260 is preferably a first impurity-doped region with a higher concentration than the second impurity-doped region 230, and the impurity doping concentration of the guide wall 260 preferably decreases as it extends upward, but the present invention is not limited to this. In addition, the first region 261 is preferably a first impurity-doped region with a lower concentration than the second contact region 240.

[0081] Figure 4 is a cross-sectional view for illustrating the structure of a single-photon avalanche diode (SPAD) according to a third embodiment of the present invention.

[0082] Next, a single-photon avalanche diode structure 3 according to a third embodiment of the present invention will be described in detail. This single-photon avalanche diode structure 3 can be formed in substantially the same manner as the single-photon avalanche diode structure 1 according to the first embodiment, except for the guide wall 360. Therefore, only the guide wall 360 will be described in detail. Furthermore, for components identical to the first embodiment, the first digit of the figure number of the first embodiment has been changed from "1" to "3."

[0083] See Figure 4In the single-photon avalanche diode structure 3 according to the third embodiment, the guide wall 360 may include a first region 361 and a second region 363. The first region 361 is a first conductive type impurity doped region, which may be in contact with the adjacent isolation region 350, or may be separated from each other in the same manner as the first region 161 according to the first embodiment. In addition, the second region 363 may be formed on the first region 361 in a manner of contacting the side of the adjacent second impurity doped region 330. At this time, the upper side surface of the first region 361 may have substantially the same height as the upper side surface of the second impurity doped region 330 in the substrate 310, or may be formed at a higher position. In addition, it is preferable that the first impurity doping concentration decreases toward the second contact region 340, the first region 361, and the second region 363, and is preferably formed in a gradual manner.

[0084] Figure 5 is a cross-sectional view for illustrating the structure of a single-photon avalanche diode (SPAD) according to a fourth embodiment of the present invention.

[0085] Next, a fourth embodiment of the single-photon avalanche diode structure 4 according to the present invention will be described in detail. This structure is substantially identical to the third embodiment of the single-photon avalanche diode structure 3, except for the second region 463 of the guide wall 460. Therefore, only the guide wall 460 will be described in detail. Furthermore, for components identical to the third embodiment, the first digit of the third embodiment's figure number has been changed from "3" to "4."

[0086] See Figure 5 The single-photon avalanche diode structure 4 according to the fourth embodiment is characterized in that a second impurity-doped region 430 is formed inside the second region 463. That is, the second region 463 is not ring-shaped or disk-shaped, but has a continuous shape without an open opening O. For example, the second region 463 can be formed in a manner having a continuous shape that contacts a pair of adjacent isolation regions 450. Therefore, the second region 463 is formed in a manner that surrounds the second impurity-doped region 430. That is, the second impurity-doped region 430 can be formed in the second region 463 in a manner that is doped with the first impurity at a lower concentration than the second region 463. By adopting the configuration described above, misalignment between the first impurity-doped region 420 and the second impurity-doped region 430 on its upper side can be prevented.

[0087] Figures 6 to 11 It is a cross-sectional view for explaining a method for manufacturing a single photon avalanche diode (SPAD) structure according to one embodiment of the present invention.

[0088] Next, a method for manufacturing a single-photon avalanche diode (SPAD) structure according to one embodiment of the present invention will be described in detail with reference to the accompanying drawings. The method for manufacturing the SPAD structure will be described exemplarily based on the method for manufacturing the SPAD structure according to the third embodiment of the present invention.

[0089] First, see Figure 6 , forming an isolation region 350 within the substrate 310. The isolation region 350 described above can be formed by forming a mask pattern (not shown) on the front surface 311 of the substrate 310 and then performing a first impurity ion implantation process. The isolation region 350 can extend from the front surface 311 toward the back surface 313 of the substrate 310 to a certain depth.

[0090] Next, see Figure 7 A second region 363 is formed within the substrate 310 in the unit pixel partitioned by the isolation region 350. The second region 363 is a low-concentration doped region of the first impurity and can be formed by forming a mask pattern (not shown) on the front surface 311 of the substrate 310 and then performing an ion implantation process. The second region 363 can be formed in a ring or disk shape with an open opening O.

[0091] At this time, similar to the single-photon avalanche diode structure 4 of the fourth embodiment, the second region 463 may also be formed continuously without forming the open opening O.

[0092] Next, see Figure 8 , a second impurity-doped region 330 can be formed inside the second region 363 in the substrate 310, and a first impurity-doped region 320 can be formed in sequence on the side of the front surface 311 of the substrate 310. The second impurity-doped region 330 is a first impurity-doped region with a lower concentration than that of the second region 363, and the first impurity-doped region 320 is preferably a second impurity-doped region with a low concentration. At this time, the bottom surface of the second impurity-doped region 330 can be located on a side adjacent to the front surface 311 in the substrate 310 compared to the bottom surface of the second region 363, or can be formed at substantially the same depth / height. The second impurity-doped region 330 and the first impurity-doped region 320 can be formed by forming a mask pattern (not shown) on the front surface 311 of the substrate 310 and then performing ion implantation processes respectively.

[0093] In addition, similar to the single-photon avalanche diode structure 4 of the fourth embodiment, a second impurity-doped region 430 can be formed by doping second impurity ions into the second region 463 while continuously forming the second region 463 without forming an open opening O, thereby forming the second impurity-doped region 430 doped with the first conductive type impurities at a low concentration compared to the second region 463.

[0094] Next, see Figure 9 A first contact region 321 is formed in the first impurity-doped region 320, and a first region 361 and a second contact region 340 are formed between the front surface 311 of the substrate 310 and the isolation region 350. Each region can be formed by ion implantation using a mask pattern (not shown) formed on the front surface 311 of the substrate 310.

[0095] Next, see Figure 10 , an insulating film layer OX, metal contact regions 381 , 385 , and metal wirings 383 , 387 are formed on the front surface 311 of the substrate 310 .

[0096] See Figure 11 After grinding the back surface 313 of the substrate 310 through a subsequent process, a planarization layer 391 and micro lenses 393 are formed on the back surface 313 .

[0097] The above detailed description is an illustration of the present invention. In addition, the above content is only an illustration of the preferred embodiment of the present invention, and the present invention can be used in a variety of other combinations, changes and environments. That is, changes or modifications can be made within the scope of the inventive concept disclosed in this specification, the scope of the disclosed content described, and / or the scope of the technology or knowledge of the relevant industry. The above embodiments are only an illustration of the best state of the technical ideas for realizing the present invention, and the present invention can be subjected to various changes according to the requirements of the specific application field and use. Therefore, the present invention is not limited to the embodiment disclosed in the detailed description of the above invention.

Claims

1. A single photon avalanche diode structure, characterized in that: include: a substrate having a front surface and a back surface; a first impurity-doped region located on the front side of the substrate within the substrate; a second impurity-doped region located on the first impurity-doped region in the substrate; as well as A guide wall surrounds the sidewalls of the first impurity-doped region and the second impurity-doped region in the substrate.

2. The single photon avalanche diode structure according to claim 1, characterized in that: The guide wall is a first conductive type impurity doped region, The first impurity-doped region is a second conductivity type impurity-doped region.

3. The single photon avalanche diode structure according to claim 2, characterized in that: The guide wall includes a first area extending upward from the front side to the back side of the substrate.

4. The single photon avalanche diode structure according to claim 3, characterized in that: An upper side surface of the first region is located at a higher position than an upper side surface of the second impurity-doped region in the substrate.

5. The single photon avalanche diode structure according to claim 3, characterized in that: The guide wall further includes a second region extending on the first region toward an upper side surface of an adjacent second impurity-doped region.

6. The single photon avalanche diode structure according to claim 5, characterized in that: The second region is in contact with the second impurity-doped region.

7. The single photon avalanche diode structure according to claim 5, characterized in that: The second region is formed to have an opening in which at least a portion of the upper side surface of the second impurity-doped region is open.

8. The single photon avalanche diode structure according to claim 5, characterized in that: The second region is a region doped with first conductive type impurities at a lower concentration than that of the first region.

9. The single photon avalanche diode structure according to claim 2, characterized in that: Also includes: a first contact region located in the first impurity-doped region on the front side of the substrate; as well as A second contact region is located on the front side of the substrate and is spaced apart from the first contact region.

10. The single photon avalanche diode structure according to claim 5, characterized in that: The invention also includes a guard ring, which is located between the guide wall and the adjacent first impurity-doped region and the second impurity-doped region.

11. The single photon avalanche diode structure according to claim 10, characterized in that: The guard ring is a region doped with first conductive type impurities at a lower concentration than the first region and the second region.

12. A single photon avalanche diode structure, characterized in that: include: a substrate having a front surface and a back surface; an isolation area located on one side of a unit pixel boundary; a first impurity-doped region located on the front side of the substrate within the substrate; a second impurity-doped region located on the first impurity-doped region in the substrate; a first contact region located in the first impurity-doped region; a second contact region located between the front surface of the substrate and the isolation region; as well as a guide wall surrounding the sidewalls of the first impurity-doped region and the second impurity-doped region in the substrate, The guide wall comprises: a first region located on the second contact region; as well as The second region extends on the first region so as to be in contact with a sidewall of an adjacent second impurity-doped region.

13. The single photon avalanche diode structure according to claim 12, characterized in that: The first region is a first conductivity type impurity doped region having a lower concentration than the second contact region and a higher concentration than the second region.

14. The single photon avalanche diode structure according to claim 12, characterized in that: The doping concentration of the first conductive type impurities gradually decreases toward the second contact region, the first region, and the second region.

15. The single photon avalanche diode structure according to claim 12, characterized in that: The upper side surface of the second region is located at a higher position than the upper side surface of the second impurity-doped region in contact therewith.

16. The single photon avalanche diode structure according to claim 12, characterized in that: The first region is separated from a sidewall of an adjacent first impurity-doped region.

17. The single photon avalanche diode structure according to claim 12, characterized in that: The guide wall is an impurity-doped region of a type opposite to that of the first impurity-doped region.

18. A single photon avalanche diode structure, characterized in that: include: a substrate having a front surface and a back surface; a first impurity-doped region located on the front side of the substrate within the substrate; a guide wall comprising a first region separated from the first impurity-doped region in the substrate, and a second region on the first region crossing the unit pixel; as well as a second impurity-doped region located within the second region, The second impurity-doped region is a first conductivity type impurity-doped region with a lower concentration than that of the second region.

19. The single photon avalanche diode structure according to claim 18, characterized in that: The second impurity-doped region is formed by implanting second conductive type impurities into the second region after forming the second region.

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