Preparation Method of Photodiode and Semiconductor Device

Abstract

The present application relates to a method for preparing a photosensitive diode and a semiconductor device. The method for preparing the photosensitive diode includes: providing a substrate, and growing a first oxide layer on the front and back surfaces of the substrate respectively; etching away the first oxide layer on the back surface of the substrate and the first oxide layer on the peripheral side of the front surface of the substrate by means of wet etching; performing diffusion treatment on the front and back surfaces of the substrate and the front and side surfaces of the first oxide layer to generate a first doped region; performing high-temperature push-annealing on the front and back surfaces of the substrate, and growing a second oxide layer on the front surface of the first oxide layer, the front surface of the first doped region, and the back surface of the first doped region respectively; etching away the first oxide layer and the second oxide layer on the front surface of the substrate by means of dry etching; performing diffusion treatment on the front surface of the substrate to generate a second doped region. The diffusion method in the present application has a low equipment cost, better etching uniformity and saves processes.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor devices, and particularly to a method for manufacturing a photosensitive diode and a semiconductor device. Background Art

[0002] The core of a photosensitive diode is a PN junction with photosensitive characteristics and has unidirectional conductivity. Therefore, a reverse voltage needs to be applied during operation. When there is no light illumination, there is a very small saturation reverse leakage current, that is, dark current, and at this time the photosensitive diode is cut off. When illuminated, the saturation reverse leakage current increases greatly, forming a photocurrent, which changes with the intensity of the incident light. When light irradiates the PN junction, electron-hole pairs can be generated in the PN junction, increasing the density of minority carriers. These carriers drift under the reverse voltage, increasing the reverse current.

[0003] For the preparation of the doped regions of a photosensitive diode, ion implantation is mostly used for doping. However, the price of ion implanters on the market is expensive, and the purchase is restricted, and the procurement cycle is long. During processing, double-sided doping of the substrate requires ion implantation to be carried out in two steps, resulting in the problem of cumbersome processing steps for semiconductor devices. In addition, when ion implantation is performed, wet etching is mostly combined to etch the oxide layer, which will cause the problem of side etching and affect the final output quality of the photosensitive diode. Summary of the Invention

[0004] The present application aims to provide a method for manufacturing a photosensitive diode and a semiconductor device to solve problems such as expensive ion implantation equipment, numerous steps, and difficulty in wet etching and directional etching.

[0005] In a first aspect, an embodiment of the present application provides a method for manufacturing a photosensitive diode, including:

[0006] Providing a substrate, and growing a first oxide layer on the front and back surfaces of the substrate respectively;

[0007] Etching away the first oxide layer on the back surface of the substrate and the first oxide layer on the peripheral side of the front surface of the substrate by means of wet etching;

[0008] Performing diffusion treatment on the front and back surfaces of the substrate and the front and side surfaces of the first oxide layer to generate a first doped region;

[0009] Performing high-temperature push-annealing on the front and back surfaces of the substrate, and growing a second oxide layer on the front surface of the first oxide layer, the front surface of the first doped region, and the back surface of the first doped region respectively;

[0010] Etching away a part of the first oxide layer and a part of the second oxide layer on the front surface of the substrate by means of dry etching;

[0011] Performing diffusion treatment on the front surface of the substrate to generate a second doped region.

[0012] In the step of performing diffusion treatment on the front and back of the substrate and the front and side surfaces of the first oxide layer to generate a first doped region, it includes: placing the substrate in a high-temperature furnace, introducing boron into the high-temperature furnace, and performing boron source diffusion treatment on the front and back of the substrate and the front and side surfaces of the first oxide layer.

[0013] Wherein, the boron source is a chemical substance containing boron-30.

[0014] In the step of etching away the first oxide layer and the second oxide layer at the center position on the front surface of the substrate by dry etching, it further includes: performing anisotropic etching on the first oxide layer and the second oxide layer on the front surface of the substrate.

[0015] In the step of performing diffusion treatment on the front surface of the substrate to generate a second doped region, it includes: placing the substrate in a high-temperature furnace, introducing phosphorus oxychloride into the high-temperature furnace, and performing phosphorus oxychloride diffusion treatment on the center position of the front surface of the substrate.

[0016] In the step of placing the substrate in a high-temperature furnace, introducing phosphorus oxychloride into the high-temperature furnace, and performing phosphorus oxychloride diffusion treatment on the center position of the front surface of the substrate, 0.5L ± 0.1L of phosphorus oxychloride is introduced into the high-temperature furnace at 950°C ± 50°C, and 10L ± 2L of nitrogen and 0.2L ± 0.05L of oxygen are introduced, and the process time is 16min ± 2min.

[0017] After the step of performing diffusion treatment on the front surface of the substrate to generate a second doped region, it further includes: growing sacrificial layers on the front surface of the second doped region, the front surface of the second oxide layer, and the back surface of the second oxide layer by high-temperature pushing in the furnace, and removing the sacrificial layers, part of the second oxide layer, and the organic substances remaining on the surface of the second oxide layer by pickling.

[0018] After the step of growing sacrificial layers on the front surface of the second doped region, the front surface of the second oxide layer, and the back surface of the second oxide layer by high-temperature pushing in the furnace, and removing the sacrificial layers, part of the second oxide layer, and the organic substances remaining on the surface of the second oxide layer by pickling, it further includes: forming an antireflection layer on the front surface of the second doped region and the front surface of the second oxide layer by chemical vapor deposition.

[0019] After the step of depositing the antireflection layer on the front surface of the second doped region and the front surface of the second oxide layer, it further includes: etching via holes on the antireflection layer by wet etching, growing a first electrode on the via holes, and growing a second electrode on the back surface of the first doped region.

[0020] Second aspect, an embodiment of the present application further provides a semiconductor device, which is made by using the method for manufacturing a photosensitive diode described above. The semiconductor device includes: a substrate; a first doped region doped on the back surface of the substrate and the peripheral side of the front surface of the substrate; a second doped region doped at the central position of the front surface of the substrate; a first oxide layer formed on the front surface of the substrate; and a second oxide layer formed on a side of the first oxide layer away from the substrate.

[0021] According to the method for manufacturing a photosensitive diode and a semiconductor device provided by an embodiment of the present application, in the method for manufacturing the photosensitive diode, first, both the first doped region and the second doped region are formed by diffusion instead of ion implantation, which greatly reduces the equipment cost, and the two diffusion steps can be completed in one step respectively. Compared with the step-by-step completion of ion implantation, the process steps are saved and the working efficiency is improved; secondly, the diffusion method will not scratch the substrate, so there is no need to thin the substrate thickness, which saves process steps and further improves the working efficiency; finally, when performing the first photolithography, wet etching is used for the front and back surfaces of the substrate, which can achieve large-area and rapid etching. When performing the second photolithography, dry etching is used for the central position of the front surface of the substrate, which can achieve anisotropy in the etching profile, prevent side etching, reduce the peeling or adhesion of the photoresist, have good etching uniformity, reduce the use of chemicals during etching, and have good safety and low cost. Description of the Drawings

[0022] The features, advantages and technical effects of the exemplary embodiments of the present application will be described below with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals. The drawings are not drawn to actual scale and are only used to illustrate the relative positional relationship. The layer thicknesses of some parts are drawn in an exaggerated manner for ease of understanding, and the layer thicknesses in the drawings do not represent the proportional relationship of the actual layer thicknesses.

[0023] Figure 1 A flowchart showing a method for manufacturing a photosensitive diode provided by the present application;

[0024] FIG. 2(a) shows a schematic diagram of the state after the first oxide layer is grown on the front and back surfaces of the substrate in a method for manufacturing a photosensitive diode provided by the present application;

[0025] FIG. 2(b) shows a schematic diagram of the state after the first oxide layer is subjected to the first photolithography in a method for manufacturing a photosensitive diode provided by the present application;

[0026] FIG. 2(c) shows a schematic diagram of the state during the diffusion of the substrate in a method for manufacturing a photosensitive diode provided by the present application;

[0027] FIG. 2(d) shows a schematic diagram of the state where the first doped region is formed on the substrate in a method for manufacturing a photosensitive diode provided by the present application;

[0028] Figure 2(e) shows a schematic diagram of the state after the first doped region is generated on the substrate of a method for manufacturing a photosensitive diode provided by the present application, and the second oxide layer is grown by high-temperature diffusion pushing;

[0029] Figure 2(f) shows a schematic diagram of the state after the second photolithography of the substrate of a method for manufacturing a photosensitive diode provided by the present application, and then diffusion is performed to generate the second doped region;

[0030] Figure 2(g) shows a schematic diagram of the state after the second doped region is generated on the substrate of a method for manufacturing a photosensitive diode provided by the present application, and the sacrificial layer is generated by high-temperature diffusion pushing;

[0031] Figure 2(h) shows a schematic diagram of the state after the sacrificial layer is removed by the third photolithography and the antireflection layer is grown on the substrate of a method for manufacturing a photosensitive diode provided by the present application;

[0032] Figure 2(i) shows a schematic diagram of the state after the antireflection layer on the substrate of a method for manufacturing a photosensitive diode provided by the present application forms a lead hole through the fourth photolithography;

[0033] Figure 3 shows a cross-sectional view of a semiconductor device provided by the present application.

[0034] Description of reference numerals:

[0035] 1. Substrate; 21. First doped region; 22. Second doped region; 31. First electrode; 32. Second electrode; 4. First oxide layer; 5. Second oxide layer; 6. Sacrificial layer; 7. Antireflection layer; 71. Lead hole. Detailed implementation manners

[0036] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In the following detailed description, many specific details are set forth in order to provide a comprehensive understanding of the present application. However, it will be apparent to those skilled in the art that the present application may be practiced without some of these specific details. The following description of the embodiments is only intended to provide a better understanding of the present application by showing examples of the present application. In the drawings and the following description, at least some of the well-known structures and technologies are not shown in order to avoid unnecessarily obscuring the present application; and, for clarity, the dimensions of the regional structures may be exaggerated. In addition, the features, structures, or characteristics described below may be combined in any suitable manner in one or more embodiments.

[0037] The orientation terms used in the following description are all the directions shown in the figures, and do not limit the specific structure of the present application. In the description of the present application, it should also be noted that unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0038] A semiconductor device is an electronic device with conductivity between that of a good conductor and an insulator, which utilizes the special electrical properties of semiconductor materials to perform specific functions.

[0039] Specifically, semiconductor devices mainly include P-type diodes and N-type diodes. Among them, in the main region of the P-type diode, there is a substrate and a P-type epitaxial layer, and P+ doped regions and N+ doped regions are formed in the P-type epitaxial layer; in the main region of the N-type diode, there is a substrate and an N-type epitaxial layer, and P+ doped regions and N+ doped regions are formed in the N-type epitaxial layer.

[0040] Taking the P-type diode as an example below, the preparation method and layered structure of its doped regions will be described.

[0041] First Embodiment

[0042] Figure 1 The flowchart showing a method for preparing a photosensitive diode provided by the present application is shown.

[0043] Please refer to Figure 1 As shown, the embodiment of the present application provides a method for preparing a photosensitive diode, including the following steps:

[0044] S001. Provide a substrate 1, and grow a first oxide layer 4 on the front and back surfaces of the substrate 1 respectively;

[0045] S002. Etch away the first oxide layer 4 on the back surface of the substrate 1 and the first oxide layer 4 on the peripheral side of the front surface of the substrate 1 by wet etching;

[0046] S003. Perform diffusion treatment on the front and back surfaces of the substrate 1 and the front and side surfaces of the first oxide layer 4 to generate a first doped region 21;

[0047] S004. Perform high-temperature pushing and annealing on the front and back surfaces of the substrate 1, and grow a second oxide layer 5 on the front surface of the first oxide layer 4, the front surface of the first doped region 21, and the back surface of the first doped region 21 respectively;

[0048] S005. Etch away a part of the first oxide layer 4 and a part of the second oxide layer 5 on the front surface of the substrate 1 by dry etching;

[0049] S006. Perform a diffusion process on the front side of the substrate 1 to generate the second doped region 22.

[0050] Among them, the material of the substrate 1 is polysilicon, specifically a P-type zone-melted wafer. The thickness of the substrate 1 is 300 μm. Compared with the 600 μm in the prior art, the thickness of the substrate 1 in this application is thinner. During the preparation process, since the diffusion does not cause scratches or other damages to the substrate 1, the substrate 1 does not need to be thinned during the preparation process. Therefore, a substrate 1 with a thickness of 300 μm can be selected. Compared with the ion implantation in the prior art, the process steps are reduced and the working efficiency is improved.

[0051] Figure 2(a) shows a schematic diagram of the state of the front and back sides of the substrate 1 after growing the first oxide layer 4 in a method for preparing a photosensitive diode provided by this application.

[0052] Please refer to Figure 2(a). In step S001, the thickness of the first oxide layer 4 on both the front and back sides of the substrate 1 is 6300 Å ± 500 Å. The first oxide layer 4 can be grown on both the front and back sides of the substrate 1 by the diffusion method of introducing nitrogen and oxygen into a high-temperature furnace. The first oxide layer 4 is mostly made of silicon oxide.

[0053] Figure 2(b) shows a schematic diagram of the state of the first oxide layer 4 after one lithography in a method for preparing a photosensitive diode provided by this application.

[0054] Please refer to Figure 2(b). Through the cutoff ring lithography, the position of the first oxide layer 4 corresponding to the first doped region 21 is etched away, that is, the first oxide layer 4 on the back side of the substrate 1 and the first oxide layer 4 on the peripheral side of the front side of the substrate 1 are etched away. Then, the photoresist is removed by the wet etching method. Since the coverage area of the photoresist is large, the excess photoresist is removed by the wet etching method, which is time-saving and efficient.

[0055] Figure 2(c) shows a schematic diagram of the state of the substrate 1 during diffusion in a method for preparing a photosensitive diode provided by this application.

[0056] Please refer to Figure 2(c). In step S003, the substrate 1 is placed in a high-temperature furnace, and boron is introduced into the high-temperature furnace. Boron source diffusion treatment is performed on the front and back sides of the substrate 1 and the front and side surfaces of the first oxide layer 4. Specifically, the boron source is a chemical substance containing boron 30 (B30), that is, a chemical substance with a boron content higher than 30%, to make the diffusion uniform and the doping concentration of each part of the generated doped region the same.

[0057] Figure 2(d) shows a schematic diagram of the state of the substrate 1 generating the first doped region 21 in a method for preparing a photosensitive diode provided by this application.

[0058] Referring to Fig. 2(d), in step S003, after boron source diffusion, it is doped into a relatively shallow position of the substrate 1, thereby forming the first doped region 21. Then, it is sent into a diffusion furnace for deposition at a temperature of 1000 °C, and the junction depth of the first doped region 21 is 1.7 μm.

[0059] Fig. 2(e) shows a schematic diagram of the state of the substrate 1 in the method for preparing a photosensitive diode provided by the present application after generating the first doped region 21 and then performing high-temperature push-junction to grow the second oxide layer 5.

[0060] Referring to Fig. 2(e), in step S004, the substrate 1 undergoes high-temperature push-junction to generate the second oxide layer 5 with a thickness of 3000 Å - 5000 Å. The second oxide layer 5 is made of silicon oxide material. Specifically, the high-temperature push-junction is for 125 minutes, the push-junction temperature is at 900 °C ± 200 °C, 2 L of wet oxygen and 10 L of dry oxygen are introduced during the push-junction, and the push-junction time is 10 minutes.

[0061] Fig. 2(f) shows a schematic diagram of the state of the substrate 1 in the method for preparing a photosensitive diode provided by the present application after the second lithography and then diffusion to generate the second doped region 22.

[0062] Referring to Fig. 2(f), in steps S005 and S006, the first oxide layer 4 and the second oxide layer 5 on the front surface of the substrate 1 are removed by dry etching, and then it is sent into a diffusion furnace, and phosphorus oxychloride is introduced for high-temperature diffusion to generate the second doped region 22, and the junction depth of the second doped region 22 is 3 μm. Among them, part of the first oxide layer 4 and the second oxide layer 5 refers to the first oxide layer 4 and the second oxide layer 5 located at the center position of the front surface of the substrate 1.

[0063] Among them, when phosphorus oxychloride is diffused, 0.5 L ± 0.1 L of phosphorus oxychloride is introduced into a high-temperature furnace at 950 °C ± 50 °C, 10 L ± 2 L of nitrogen and 0.2 L ± 0.05 L of oxygen are introduced, and the process time is 16 min ± 2 min. When ensuring appropriate diffusion temperature and process time, introducing nitrogen and oxygen helps the diffusion to proceed quickly, and the above temperature and process time are to prevent impurities from entering the substrate 1.

[0064] During dry etching, it also includes anisotropic etching of the first oxide layer 4 and the second oxide layer 5 on the front surface of the substrate 1 to precisely meet the requirements of the etching depth. Specifically, the dry etching profile is anisotropic, which can prevent side etching, has good etching uniformity, and dry etching does not cause problems such as photoresist peeling or adhesion. Compared with wet etching, dry etching uses fewer chemicals, is safer, and has lower costs.

[0065] Fig. 2(g) shows a schematic diagram of the state of the substrate 1 in the method for preparing a photosensitive diode provided by the present application after generating the second doped region 22 and then performing high-temperature push-junction to generate the sacrificial layer 6.

[0066] As shown in Fig. 2(g), after the second doped region 22 is formed, by means of high-temperature diffusion, using nitrogen as the raw material, sacrificial layers 6 are grown on the front surface of the second doped region 22, the front surface of the second oxide layer 5, and the back surface of the second oxide layer 5 respectively. Specifically, the thickness of the sacrificial layer 6 is 300A - 600A.

[0067] Fig. 2(h) shows a schematic diagram of the state of the substrate 1 of a method for manufacturing a photosensitive diode provided by the present application after the third photolithography to remove the sacrificial layer 6 and grow the antireflection layer 7.

[0068] As shown in Fig. 2(h), after the step of growing the sacrificial layer 6, it further includes: removing the sacrificial layer 6, a part of the second oxide layer 5, and the organic matter remaining on the surface of the second oxide layer 5 by pickling. The antireflection layer 7 is deposited on the front surface of the second doped region 22 and the front surface of the second oxide layer 5. The thickness of the antireflection layer 7 is 1000A - 1600A, and the function of the antireflection layer 7 is to reduce the reflection of light and increase the light absorption rate of the P-type photosensitive device.

[0069] Specifically, the antireflection layer 7 is formed by Chemical Vapor Deposition (CVD for short). Chemical vapor deposition refers to a gas-phase reaction at high temperature. For example, thermal decomposition of metal halides, organometals, hydrocarbons, etc., hydrogen reduction, or chemical reaction of its mixed gas at high temperature to precipitate inorganic materials such as metals, oxides, and carbides. The formation of the antireflection layer 7 does not require the step of photolithography, reducing the manufacturing cost, shortening the manufacturing cycle, and saving time cost.

[0070] Fig. 2(i) shows a schematic diagram of the state of the antireflection layer 7 of the substrate 1 of a method for manufacturing a photosensitive diode provided by the present application after the fourth photolithography to form a via hole.

[0071] As shown in Fig. 2(i), after the step of depositing the antireflection layer 7, it further includes: etching a via hole in the antireflection layer 7 by wet etching.

[0072] Figure 3 Shows a cross-sectional view of a semiconductor device provided by the present application.

[0073] Please refer to Figure 3As shown, after the step of etching the lead holes 71 on the antireflection layer 7 by wet etching, the following steps are further included: growing a first electrode 31 on the lead holes 71, and growing a second electrode 32 on the back surface of the first doped region 21. The first electrode 31 is the positive electrode, which is formed by depositing metallic aluminum, and the thickness of the first electrode 31 is 2 μm - 2.4 μm. The second electrode 32 is the negative electrode, which is formed by depositing metallic silver, and the negative electrode is formed by sequentially depositing metallic titanium, metallic nickel, and metallic silver from bottom to top.

[0074] In summary, since the diffusion process is adopted in this application to fabricate the first doped region 21 and the second doped region 22, and the area occupied by the first doped region 21 is relatively large, therefore, before fabricating the first doped region 21, it is necessary to rapidly etch a part of the first oxide layer 4 on the front and back surfaces of the substrate 1 by wet etching. When fabricating the second doped region 22, since the area occupied by the second doped region 22 is relatively small, the dry etching method is adopted for directional etching, and there will be no side etching, which does not affect other structures. Finally, by the above method, only four photolithography steps are required to form, and there is no need to thin the substrate 1. The steps are few, the process is simple, and the cost is low.

[0075] It should be noted that in the above photolithography steps: first select the material layer, coat the photoresist, expose, develop to remove the photoresist, perform dry etching or wet etching, and finally remove the remaining photoresist. This is the complete photolithography process.

[0076] In addition, the above high-temperature furnaces are all atmospheric-pressure diffusion furnace tubes. The atmospheric-pressure diffusion furnace tube is one of the important process equipment in the front process of the semiconductor production line, and is used for processes such as diffusion, oxidation, annealing, alloying, and sintering in industries such as large-scale integrated circuits, discrete devices, power electronics, optoelectronic devices, and optical fibers.

[0077] The process steps not elaborated in detail in the process are all conventional process processes, such as lead hole photolithography, lead hole etching, acid rinsing, diffusion, photolithography, dry etching, etc., and will not be described in detail in this application.

[0078] Second Embodiment

[0079] Please continue to refer to Figure 3 As shown, this embodiment provides a semiconductor device, which is fabricated by using the preparation method of the photosensitive diode described above. The semiconductor device includes: a substrate 1; a first doped region 21 doped on the back surface of the substrate 1 and the peripheral side of the front surface of the substrate 1; a second doped region 22 doped at the central position of the front surface of the substrate 1; a first oxide layer 4 formed on the front surface of the substrate 1; and a second oxide layer 5 formed on the side of the first oxide layer 4 facing away from the substrate 1.

[0080] Among them, the first doping region 21 is a P+ doping region, and the second doping region 22 is an N+ doping region. A P+ doping region is formed by doping on the back surface of the substrate 1, and an N+ doping region is formed at the center position on the front surface of the substrate 1. The periphery of the N+ doping region is the P+ doping region, so that when the semiconductor device works, a good voltage dividing effect can be achieved.

[0081] Further, the semiconductor device further includes: an oxide layer, an antireflection layer 7, a first electrode 31, and a second electrode 32. The antireflection layer 7 is formed on the front surface of the substrate 1, and a lead hole is formed in the antireflection layer 7. The first electrode 31 is located in the lead hole, the second electrode 32 is located on the back surface of the first doping region 21, and the oxide layer is located on the front surface of the substrate 1, which includes a first oxide layer 4 on the front surface of the substrate 1 and a second oxide layer 5 formed on the side of the first oxide layer 4 away from the substrate 1.

[0082] Among them, the first electrode 31 is the positive electrode, which is formed by depositing aluminum metal, and the thickness of the first electrode 31 is 2μm - 2.4μm. The second electrode 32 is the negative electrode, which is formed by depositing silver metal, and the negative electrode is sequentially deposited with metal titanium, metal nickel, and metal silver from bottom to top.

[0083] In addition, the raw material of the substrate 1 is polysilicon, and the material of the oxide layer is silicon oxide. The thickness of the substrate 1 is 300μm. Compared with 600μm in the prior art, the thickness of the substrate 1 in this application is thinner. During the preparation process, since there are no scratches or other damages to the substrate 1 due to double-sided coating, the thickness of the substrate 1 does not need to be thinned during the preparation process. Therefore, a substrate 1 with a thickness of 300μm can be selected. Compared with ion implantation in the prior art, the process steps are reduced and the working efficiency is improved.

[0084] It should be noted that the semiconductor device in this embodiment may further include other layer structures, such as a barrier layer, an epitaxial layer, etc., which will not be elaborated here.

[0085] The technical solution of this application can be widely applied to the preparation of various semiconductor devices, such as discrete device categories such as Schottky Barrier Diode (SBD), Fast Recovery Diode (FRD), Transient Voltage Suppressor (TVS), switch diode, Rectifier Diode, light source triode, thyristor rectifier element, small signal triode, etc., and the above-mentioned scheme can be applied to all of them.

[0086] It should be readily understood that the terms "on", "above", and "over" in this application should be construed in the broadest manner so that "on" not only means "directly on something", but also includes the meaning of "on something" with intermediate features or layers therebetween, and "above" or "over" not only includes the meaning of "above" or "over something", but may also include the meaning of "above" or "over something" with no intermediate features or layers therebetween (i.e., directly on something).

[0087] The term "layer" as used herein may refer to a portion of material including a region having a certain thickness. A layer may extend over an entire underlying or overlying structure, or may have a smaller extent than the underlying or overlying structure. Further, a layer may be a region of a homogeneous or non-homogeneous continuous structure, the thickness of which is less than the thickness of the continuous structure. For example, a layer may be located between the top and bottom surfaces of the continuous structure or between any pair of lateral planes at the top and bottom surfaces. A layer may extend laterally, vertically, and / or along a conical surface. A semiconductor device may be a layer, may include one or more layers therein, and / or may have one or more layers located thereon, above it, and / or below it. A layer may include a plurality of layers. For example, an interconnect layer may include one or more conductors and contact layers (in which contacts, interconnect lines, and / or vias are formed) and one or more dielectric layers.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a photosensitive diode, characterized in that, Including: Providing a substrate, and growing a first oxide layer on the front and back surfaces of the substrate respectively; Etching away the first oxide layer on the back surface of the substrate and the first oxide layer on the peripheral side of the front surface of the substrate by wet etching; Performing diffusion treatment on the front and back surfaces of the substrate and the front and side surfaces of the first oxide layer, doping into relatively shallow positions of the substrate, thereby generating a first doped region; Performing high-temperature push-annealing on the front and back surfaces of the substrate, and growing a second oxide layer on the front surface of the first oxide layer, the front surface of the first doped region, and the back surface of the first doped region respectively; Etching away a part of the first oxide layer and a part of the second oxide layer on the front surface of the substrate by dry etching, including: performing anisotropic etching on the first oxide layer and the second oxide layer on the front surface of the substrate; Performing diffusion treatment on the front surface of the substrate to generate a second doped region.

2. The manufacturing method of the photosensitive diode according to claim 1, characterized in that, In the step of performing diffusion treatment on the front and back surfaces of the substrate and the front and side surfaces of the first oxide layer to generate a first doped region, it includes: placing the substrate in a high-temperature furnace, introducing boron into the high-temperature furnace, and performing boron-source diffusion treatment on the front and back surfaces of the substrate and the front and side surfaces of the first oxide layer.

3. The manufacturing method of the photosensitive diode according to claim 2, characterized in that, The boron source is a chemical substance containing 30% boron.

4. The manufacturing method of the photosensitive diode according to claim 1, characterized in that In the step of performing diffusion treatment on the front surface of the substrate to generate a second doped region, it includes: placing the substrate in a high-temperature furnace, introducing phosphorus oxychloride into the high-temperature furnace, and performing phosphorus-oxychloride diffusion treatment on the central position of the front surface of the substrate.

5. The manufacturing method of the photosensitive diode according to claim 4, characterized in that, In the step of placing the substrate in a high-temperature furnace, introducing phosphorus oxychloride into the high-temperature furnace, and performing phosphorus-oxychloride diffusion treatment on the central position of the front surface of the substrate, introduce 0.5L ± 0.1L of phosphorus oxychloride into a high-temperature furnace at 950°C ± 50°C, and introduce 10L ± 2L of nitrogen and 0.2L ± 0.05L of oxygen, and the process time is 16min ± 2min.

6. The manufacturing method of the photosensitive diode according to claim 1, characterized in that After the step of performing diffusion treatment on the front surface of the substrate to generate a second doped region, it further includes: growing a sacrificial layer on the front surface of the second doped region, the front surface of the second oxide layer, and the back surface of the second oxide layer by performing high-temperature push-annealing in the furnace, and removing the sacrificial layer, a part of the second oxide layer, and the organic matter remaining on the surface of the second oxide layer by pickling with acid.

7. The manufacturing method of the photosensitive diode according to claim 6, characterized in that, After the step of growing a sacrificial layer on the front surface of the second doped region, the front surface of the second oxide layer, and the back surface of the second oxide layer by performing high-temperature push-annealing in the furnace, and removing the sacrificial layer, a part of the second oxide layer, and the organic matter remaining on the surface of the second oxide layer by pickling with acid, it further includes: forming an antireflection layer on the front surface of the second doped region and the front surface of the second oxide layer by chemical vapor deposition.

8. The manufacturing method of the photosensitive diode according to claim 7, characterized in that, After the step of depositing an antireflection layer on the front surface of the second doped region and the front surface of the second oxide layer, it further includes: etching a lead hole on the antireflection layer by wet etching, growing a first electrode on the lead hole, and growing a second electrode on the back surface of the first doped region.

9. A semiconductor device is fabricated by using the method for preparing a photosensitive diode according to any one of claims 1-8, characterized in that, The semiconductor device includes: A substrate; A first doped region, doped on the back surface of the substrate and the peripheral side of the front surface of the substrate by a diffusion treatment method; A second doped region, doped at the central position of the front surface of the substrate; A first oxide layer, formed on the front surface of the substrate; and, A second oxide layer is formed on a side of the first oxide layer facing away from the substrate.

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