A nuclear battery based on a three-dimensional through-hole structure and its fabrication method

Abstract

This invention discloses a nuclear battery based on a three-dimensional through-hole structure and its fabrication method. The nuclear battery includes a three-dimensional through-hole PIN junction semiconductor transducer unit, a radiation source, and an electrode layer. The unit, from top to bottom, consists of a P-type semiconductor layer, an intrinsic semiconductor layer, and an N-type semiconductor layer. The radiation source is filled in the intrinsic semiconductor through-holes, while the P-type and N-type semiconductor through-holes are filled with electrically insulating materials. The method includes: obtaining a PIN structure on a semiconductor substrate; etching a three-dimensional through-hole array; fabricating a metal seed layer at the bottom of the array; filling the N-type semiconductor through-holes with conductive materials; filling the intrinsic semiconductor through-holes with radiation source material; filling the P-type semiconductor through-holes with electrically insulating materials; and converting the conductive materials in the N-type semiconductor through-holes into electrically insulating materials. This invention improves the energy deposition of radioactive decay particles within the intrinsic layer and the conversion efficiency of radioactive decay energy to electrical energy, thus achieving the fabrication of a high-output performance nuclear battery.

Description

Technical Field

[0001] This invention relates to the fields of semiconductor materials technology and nuclear technology applications, specifically to a nuclear battery based on a three-dimensional through-hole structure and its preparation method. Background Technology

[0002] Nuclear batteries are miniature energy sources that use semiconductor materials to convert the decay energy of a radioactive source into electrical energy. They can be used in extremely harsh working environments such as the deep sea, deep space, and polar regions, where existing miniature energy sources cannot adapt to strong radiation, high vacuum, and difficulties in charging or replacing. They have important scientific and application value for human beings to go to deep space, deep sea, and polar regions.

[0003] Currently, nuclear batteries primarily involve fabricating a radioactive source as a planar thin film and placing it on the surface of a semiconductor transducer. However, due to the radioactive source's absorption effect and the limited energy deposition depth of its decaying particles within the semiconductor, the ability to convert radioactive decay energy into electrical energy is limited, hindering the effective improvement of nuclear battery output performance. Based on a review of domestic and international literature (Diamond & Related Materials, 2018, 84:41-47; ECS Journal of Solid State Science and Technology, 2021, 10:027005), the experimentally tested maximum output power of planar nuclear batteries is approximately 10 μW / cm². 3 The limited technology significantly restricts its application. Researchers have discovered that loading a radioactive source into a semiconductor transducer with a three-dimensional structure can effectively improve the energy deposition of radioactive decay particles within the transducer, thereby significantly improving the battery's output performance. For example, Gao Hui et al. from the China Academy of Engineering Physics (Energy, 2013, 51:116-122) found through simulation calculations that, compared to a planar transducer model, fully filling a porous structure with a pore size of 3–4 μm and a depth-to-diameter ratio of 10:1 significantly improves the battery's output performance. 63 Ni radioactive sources can increase the radioactive source loading by 5 times, and the effective energy deposition in the transducer element can be increased by 18 times. Murphy et al. (AIPAdvances, 2019, 9:065208) at Lawrence Livermore National Laboratory in the United States designed a three-dimensional microgroove structure nuclear battery through simulation and found that if... 147 With the Pm₂O₃ source completely filling the microgroove structure, the maximum power density and energy conversion efficiency of the Si-based and 4H-SiC-based three-dimensional microgroove nuclear batteries are 24.1 mW / cm², respectively. 3 and 85mW / cm 3 This can significantly improve the output power density of nuclear batteries.

[0004] Qiao Dayong et al. from Northwestern Polytechnical University proposed using PIN junctions as energy conversion units in nuclear batteries, which can overcome the shortcomings of short minority carrier lifetime and narrow depletion layer width in traditional PN junctions, and increase the collection space and collection efficiency of electron-hole pairs (Acta Physica Sinica, 2011, 2: 020701). However, due to the partial blocking effect of the P layer on radioactive decay particles and the fact that some high-energy particles are not deposited in the intrinsic (I layer) depletion region, the generated electron-hole pairs can only diffuse into the depletion region to form current by relying on the minority carrier diffusion length. However, the minority carrier diffusion length is often relatively small, and electrons and holes exceeding the minority carrier diffusion range cannot achieve electrical energy conversion (Nuclear Technology, 2021, 208: 922-934). Therefore, how to deposit as much energy as possible of radioactive decay particles in the intrinsic (I layer) is the key to improving the output performance of nuclear batteries. Meanwhile, the complete filling of radioactive sources in microstructures with high aspect ratios is a critical technical bottleneck that needs to be addressed in current three-dimensional nuclear batteries. Researchers at Lawrence Livermore National Laboratory (Journal of Electronic Materials, 2021, 50: 1380-1385) have used an improved drop casting technique to... 147 When a Pm source is filled in a high aspect ratio Si deep trench semiconductor material, due to limitations in the radiation source filling technology, the radiation source is deposited only at the bottom of the Si deep trench, resulting in a maximum initial output power of only 200nW. Therefore, a new solution is urgently needed to address the above problem. Summary of the Invention

[0005] The purpose of this invention is to provide a nuclear battery based on a three-dimensional through-hole structure and its preparation method. The through-hole three-dimensional structure nuclear battery prepared by the preparation method described in this invention solves the problem of loading radioactive sources in traditional high aspect ratio three-dimensional structures. By loading the radioactive source into the intrinsic (I-layer) semiconductor through-hole, the energy deposition of radioactive decay particles in the intrinsic layer (I-layer) is improved, thereby improving the conversion efficiency of radioactive decay energy to electrical energy and realizing the development of a high-output performance nuclear battery.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A nuclear battery based on a three-dimensional via structure, the nuclear battery structure including a three-dimensional via PIN junction semiconductor transducer unit, a radiation source, and an electrode layer; the three-dimensional via PIN junction semiconductor transducer unit, from top to bottom, consists of a P-type semiconductor layer, an intrinsic (I) semiconductor layer, and an N-type semiconductor layer; the three-dimensional via PIN junction semiconductor transducer unit is provided with a three-dimensional via array penetrating the P-type semiconductor layer, the intrinsic (I) semiconductor layer, and the N-type semiconductor layer; the three-dimensional via array includes multiple vias, each via penetrating the P-type semiconductor layer is a P-type semiconductor via, each via penetrating the intrinsic (I) semiconductor layer is an intrinsic (I) semiconductor via, and each via penetrating the N-type semiconductor layer is an N-type semiconductor via;

[0008] The radiation source is filled in intrinsic (I layer) semiconductor vias, and the P-type and N-type semiconductor vias are filled with electrically insulating material.

[0009] The electrode layer includes a top electrode and a back electrode, and the three-dimensional through-hole PIN junction semiconductor transducer is sandwiched between the top electrode and the back electrode.

[0010] Furthermore, an N-type semiconductor layer, an intrinsic (I-layer) semiconductor layer, a P-type semiconductor layer, and a top electrode are sequentially stacked on the back electrode.

[0011] The fabrication method of the three-dimensional through-hole structure nuclear battery as described above includes the following steps:

[0012] S1. After obtaining a PIN junction on a semiconductor substrate by diffusion, ion implantation or epitaxial growth, a three-dimensional through-hole array is etched.

[0013] S2. Prepare a metal seed layer at the bottom of the three-dimensional through-hole array, and use electroplating to fill the conductive material in the N-type semiconductor through-hole;

[0014] S3. Based on the sample prepared in step S2, fill the intrinsic (I layer) semiconductor via with radioactive source material, fill the P-type semiconductor via with electrical insulating material, and convert the conductive material filled in step S2 into electrical insulating material in the N-type semiconductor via while retaining the metal seed layer, or remove the metal seed layer and the original conductive material before filling with electrical insulating material.

[0015] S4. Sputter the top electrode and back electrode onto both sides of the filled P-type and N-type semiconductors respectively to complete the fabrication of the three-dimensional through-hole structure nuclear battery.

[0016] The material of the three-dimensional through-hole PIN junction semiconductor transducer is one of silicon, gallium arsenide, gallium nitride, silicon carbide, diamond, gallium oxide, boron nitride, aluminum nitride, or a wide bandgap semiconductor or an ultra-wide bandgap semiconductor.

[0017] The radioactive source is one of nickel-63, tritium-3, promethium-147, or a β radioactive isotope source.

[0018] The electrode layer is a composite electrode comprising any one or a combination of any of the following: platinum, gold, silver, aluminum, titanium, nickel, copper, tungsten, germanium, indium, and gallium.

[0019] Furthermore, in step S1, the thickness of the P-type semiconductor layer is 10 nm to 10 μm, and the doping concentration is 10. 17 ~10 20 cm -3 The intrinsic (I-layer) semiconductor layer has a thickness of 5–200 μm and a doping concentration of 10. 12 ~10 17 cm -3 The N-type semiconductor layer has a thickness of 10–800 μm and a doping concentration of 10. 17 ~10 20 cm -3 .

[0020] Furthermore, in step S1, the etching includes any one or any combination of chemical wet etching, physical dry etching, and laser etching. Preferably, the through-hole etching radius is 100nm to 20μm.

[0021] Furthermore, in step S2, the metal seed layer and the filling conductive material are any one of the following metal materials or alloys or composite metal conductive materials: aluminum, copper, titanium, magnesium, nickel, gold, palladium, platinum, and silver. Preferably, the seed layer thickness is 1 nm to 10 nm.

[0022] Furthermore, in step S3, filling the intrinsic (I-layer) semiconductor via with a radioactive source can be either a solid-state radioactive source or a gaseous radioactive source. Specifically, if a solid-state metal radioactive source is used, the upper part of the sample prepared in step S2 is immersed in an electroplating solution containing radioactive source particles, and the radioactive source is filled into the intrinsic (I-layer) semiconductor via by precisely controlling the electrodeposition parameters; if a gaseous radioactive source is used, based on the sample prepared in step S2, the corresponding gaseous radioactive source storage metal material or metal compound material is filled into the intrinsic (I-layer) semiconductor via, and then the gaseous radioactive source is adsorbed and filled.

[0023] Furthermore, in step S3, the electrically insulating material filled in the P-type semiconductor via is any one of oxide insulating materials, epoxy resin, silicone rubber, and polyurethane.

[0024] Furthermore, in step S3, the conductive material filled in step S2 is converted into an electrically insulating material in the N-type semiconductor via while retaining the metal seed layer, or the metal seed layer and the original conductive material are removed before filling with the electrically insulating material. Specifically, the conductive material filled in step S2 is directly converted into an oxide insulating material by thermal oxidation while retaining the metal seed layer, or the metal seed layer and the original conductive material filled inside it are removed by solution etching, and then filled with any one of epoxy resin, silicone rubber, or polyurethane.

[0025] Furthermore, the filling height of the electrically insulating material in the P-type semiconductor via is 1-10 μm higher than the thickness of the P-type semiconductor layer.

[0026] Furthermore, the filling height of the radiation source in the intrinsic (I-layer) semiconductor via is 2-20 μm lower than the thickness of the intrinsic (I-layer) semiconductor layer.

[0027] Furthermore, the filling height of the electrically insulating material in the N-type semiconductor via is 1-10 μm higher than the thickness of the N-type semiconductor layer.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] 1. The nuclear battery based on a three-dimensional through-hole structure proposed in this invention solves the problem of loading radioactive sources in traditional high aspect ratio three-dimensional structures by sputtering a metal seed layer on the bottom of the three-dimensional through-hole PIN junction semiconductor, thereby realizing three-dimensional loading of radioactive sources in the three-dimensional through-hole semiconductor.

[0030] 2. The invention proposes filling the intrinsic (I-layer) semiconductor via with a radioactive source, which can effectively reduce the blocking effect of the P-layer on the decay particles of the radioactive source, allowing more particles to be deposited in the intrinsic (I-layer) junction region, improving the conversion efficiency of radioactive source decay energy to electrical energy, and realizing the development of a high-output performance nuclear battery. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0032] Figure 1 This is a schematic diagram of a nuclear battery structure based on a three-dimensional through-hole structure proposed in this invention.

[0033] Figure 2 This is a schematic diagram of the axial cross-section of a nuclear battery based on a three-dimensional through-hole structure proposed in this invention.

[0034] Figure 3 This is a flowchart of a nuclear battery fabrication process based on a three-dimensional through-hole structure proposed in this invention.

[0035] Explanation of reference numerals in the attached figures: 1-Three-dimensional through-hole PIN junction semiconductor transducer unit, 2-Radiation source, 3-Electrode layer, 11-P-type semiconductor layer, 12-Intrinsic (I-layer) semiconductor layer, 13-N-type semiconductor layer, 14-P-type semiconductor through-hole, 15-Intrinsic (I-layer) semiconductor through-hole, 16-N-type semiconductor through-hole, 4-Electrically insulating material, 5-Metal seed layer, 6-Conductive material, 31-Top electrode, 32-Back electrode. Detailed Implementation

[0036] The technical solutions of the embodiments of the invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. Based on the embodiments of the invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the invention.

[0037] It should be noted that if the embodiments of the invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0038] Furthermore, if the embodiments of the invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, "multiple" refers to two or more. Moreover, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of a person skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the invention.

[0039] See Figure 1 , Figure 2 and Figure 3 A nuclear battery based on a three-dimensional through-hole structure, the nuclear battery structure including a three-dimensional through-hole PIN junction semiconductor transducer 1, a radiation source 2 and an electrode layer 3;

[0040] The three-dimensional via PIN junction semiconductor transducer 1 consists of, from top to bottom: a P-type semiconductor layer 11, an intrinsic (I-layer) semiconductor layer 12, and an N-type semiconductor layer 13. The three-dimensional via PIN junction semiconductor transducer 1 is provided with multiple vias penetrating the P-type semiconductor layer 11, the intrinsic (I-layer) semiconductor layer 12, and the N-type semiconductor layer 13. The portion of the via penetrating the P-type semiconductor layer 11 is a P-type semiconductor via 14, the portion penetrating the intrinsic (I-layer) semiconductor layer 12 is an intrinsic (I-layer) semiconductor via 15, and the portion penetrating the N-type semiconductor layer 13 is an N-type semiconductor via 16. The radiation source 2 is filled in the intrinsic (I-layer) semiconductor via 15, and the P-type semiconductor via 14 and the N-type semiconductor via 16 are filled with an electrically insulating material 4.

[0041] The electrode layer includes a top electrode 31 and a back electrode 32, with the three-dimensional via PIN junction semiconductor transducer 1 sandwiched between the top electrode 31 and the back electrode 32. The plurality of vias penetrating the P-type semiconductor layer 11, the intrinsic (I-layer) semiconductor layer 12, and the N-type semiconductor layer 13 form a three-dimensional via array.

[0042] The method for fabricating the three-dimensional through-hole structure nuclear battery includes the following steps:

[0043] S1. After obtaining a PIN junction on a semiconductor substrate by diffusion, ion implantation or epitaxial growth, a three-dimensional through-hole array is etched to obtain a three-dimensional through-hole PIN junction semiconductor transducer 1.

[0044] S2. Prepare a metal seed layer 5 at the bottom of the three-dimensional through-hole array, and use electroplating to fill the conductive material 6 in the N-type semiconductor through-hole.

[0045] S3. Based on the sample prepared in step S2, fill the intrinsic (I layer) semiconductor via with a radiation source 2, fill the P-type semiconductor via with an electrically insulating material 4, and convert the conductive material 6 filled in step S2 into an electrically insulating material 4 in the N-type semiconductor via while retaining the metal seed layer 5, or remove the metal seed layer 5 and the original conductive material 6 before filling with the electrically insulating material 4.

[0046] S4. Sputter the top electrode 31 and the back electrode 32 onto both sides of the filled P-type and N-type semiconductors respectively to complete the fabrication of the three-dimensional through-hole structure nuclear battery.

[0047] The material of the three-dimensional through-hole PIN junction semiconductor transducer 1 is one of silicon, gallium arsenide, gallium nitride, silicon carbide, diamond, gallium oxide, boron nitride, aluminum nitride, or wide bandgap semiconductor or ultra-wide bandgap semiconductor.

[0048] The radioactive source 2 is one of nickel-63, tritium-3, promethium-147 or beta radioactive isotope sources.

[0049] The electrode layer 3 is a composite electrode comprising any one or any combination of platinum, gold, silver, aluminum, titanium, nickel, copper, tungsten, germanium, indium, and gallium.

[0050] In step S1, the thickness of the P-type semiconductor layer 11 is 10 nm to 10 μm, and the doping concentration is 10%. 17 ~10 20 cm -3 The intrinsic (I-layer) semiconductor layer 12 has a thickness of 5–200 μm and a doping concentration of 10. 12 ~10 17 cm -3 The N-type semiconductor layer 13 has a thickness of 10–800 μm and a doping concentration of 10. 17 ~10 20 cm -3 .

[0051] In step S1, the etching includes any one or any combination of chemical wet etching, physical dry etching, and laser etching. Preferably, the through-hole etching size radius is 100nm to 20μm.

[0052] In step S2, the metal seed layer 5 and the filled conductive material 6 are any one of the following metal materials or alloys or composite metal conductive materials: aluminum, copper, titanium, magnesium, nickel, gold, palladium, platinum and silver. Preferably, the seed layer thickness is 1 nm to 10 nm.

[0053] In step S3, the filling of the intrinsic (I-layer) semiconductor via with radioactive source 2 can be either a solid radioactive source or a gaseous radioactive source. Preferably, if a solid metal radioactive source is filled, the upper part of the sample prepared in step S2 is immersed in an electroplating solution containing radioactive source particles, and the filling of the intrinsic (I-layer) semiconductor via with radioactive source is achieved by adjusting the electrodeposition parameters. Preferably, if a gaseous radioactive source is filled, based on the sample prepared in step S2, the corresponding gaseous radioactive source storage metal material or metal compound material is deposited and filled into the intrinsic (I-layer) semiconductor via, and then the gaseous radioactive source is adsorbed and filled.

[0054] In step S3, the electrical insulating material 4 filling the P-type semiconductor via is any one of oxide insulating material, epoxy resin, silicone rubber, and polyurethane.

[0055] In step S3, the conductive material 6 filled in step S2 is converted into an electrically insulating material 4 in the N-type semiconductor via while retaining the metal seed layer 5, or the metal seed layer 5 and the original conductive material 6 are removed before filling with the electrically insulating material 4. Specifically, the conductive material 6 filled in step S2 is directly converted into an oxide insulating material by thermal oxidation while retaining the metal seed layer 5, or the metal seed layer 5 and the original conductive material 6 filled inside it are removed by solution etching, and then filled with any one of epoxy resin, silicone rubber, or polyurethane.

[0056] The filling height of the electrically insulating material 4 in the P-type semiconductor via 14 is 1-10 μm higher than the thickness of the P-type semiconductor layer 11; the filling height of the radiation source 2 in the intrinsic (I-layer) semiconductor via 15 is 2-20 μm lower than the thickness of the intrinsic (I-layer) semiconductor layer 12; and the filling height of the electrically insulating material 4 in the N-type semiconductor via 16 is 1-10 μm higher than the thickness of the N-type semiconductor layer 13.

[0057] Example 1

[0058] This embodiment uses a three-dimensional through-hole silicon structure and 63 The nuclear battery based on a Ni radioactive source and its preparation method are described in detail below:

[0059] Select a 4-inch, 80μm thick N-type substrate (doping concentration 1×10⁻⁶). 18 cm -3 Using a single-crystal silicon double-polished wafer as the substrate, a 30 μm thick layer with a doping concentration of 1×10⁻⁶ was epitaxially deposited on the N-type single-crystal silicon substrate using low-pressure chemical vapor deposition. 16 cm -3 A lightly doped N-type epitaxial layer (intrinsic I layer) is formed. A layer with a doping concentration of 1×10⁻⁶ is diffused within the lightly doped N-type epitaxial layer. 19 cm -3 The highly doped p-region, approximately 5 μm thick, forms a PIN junction. A three-dimensional PIN junction structure with a via radius of 2 μm and a via spacing of 5 μm is obtained through deep reactive ion etching, as shown below. Figure 3 As shown in (a) and 3(b), the 4-inch wafer was cut into basic units with an effective area of ​​1cm × 1cm using a laser scribing machine and then placed in a moisture-proof cabinet for later use.

[0060] After cutting the basic unit, a 50nm copper seed layer is deposited at the bottom of its via array using magnetron sputtering. The upper part of the PIN junction of the via array three-dimensional structure is immersed in an electroplating solution containing copper sulfate and sulfuric acid. Pulse electroplating is then used to deposit and fill the N-type semiconductor vias with copper metal up to approximately 82μm in height. Figure 3 As shown in (c), the top part of the PIN junction, which has been filled with copper metal in the N-type semiconductor via, is re-immersed in a solution containing 20 wt% copper.63 In the Ni radioactive source electroplating solution, a pulse electroplating mode is used to... 63 A Ni radiation source is filled into the intrinsic (I-layer) semiconductor via, with a filling height of approximately 20 μm. Figure 3 As shown in (d), the copper seed layer and the copper metal filling the aforementioned N-type semiconductor vias are dissolved using a copper substrate etching solution (ammonium trichloroacetate solution), leaving only the copper metal filling the intrinsic (I-layer) semiconductor vias. 63 Ni radiation source, the electrically insulating material silicone rubber is filled into P-type semiconductor vias and N-type semiconductor vias respectively by drop casting, such as Figure 3 As shown in (e2). Figure 3 As shown in (f2), a 20nm titanium / 100nm gold composite metal electrode on the top and a 200nm aluminum metal electrode on the back were sputtered onto both the P-type and N-type semiconductors, respectively, to complete the fabrication of the three-dimensional through-hole silicon structure nuclear battery. The performance of the three-dimensional through-hole silicon structure nuclear battery was tested using a Keithley 4200-SCS parameter analyzer, and a maximum output power of 16μW / cm² was obtained. 3 .

[0061] Example 2

[0062] This embodiment uses a three-dimensional through-hole silicon structure and 63 The nuclear battery based on a Ni radioactive source and its preparation method are described in detail below:

[0063] Select a 4-inch, 50μm thick N-type substrate (doping concentration 1×10⁻⁶). 18 cm -3 Using a single-crystal silicon double-polished wafer as the substrate, a 50 μm thick layer with a doping concentration of 1×10⁻⁶ was epitaxially deposited on the N-type single-crystal silicon substrate using low-pressure chemical vapor deposition (LPCVD). 16 cm -3 A lightly doped N-type epitaxial layer (intrinsic I layer) is formed. A layer with a doping concentration of 1×10⁻⁶ is diffused within the lightly doped N-type epitaxial layer. 19 cm -3 The highly doped P-region, approximately 5 μm thick, forms a PIN junction. A three-dimensional PIN junction structure with a via radius of 0.5 μm and a spacing of 1.5 μm is obtained through deep reactive ion etching. Figure 3 As shown in (a) and 3(b), the 4-inch wafer was cut into basic units with an effective area of ​​1cm × 1cm using a laser scribing machine and then placed in a moisture-proof cabinet for later use.

[0064] After cutting the basic unit, a 50nm copper seed layer is deposited at the bottom of the via array using magnetron sputtering. The upper part of the PIN junction of the three-dimensional via array structure is immersed in an electroplating solution containing copper sulfate and sulfuric acid. Pulse electroplating is then used to deposit and fill the N-type semiconductor vias with copper metal up to a height of approximately 52μm. Figure 3 As shown in (c), the top part of the PIN junction, which has been filled with copper metal in the N-type semiconductor via, is re-immersed in a solution containing 20 wt% copper. 63 In the Ni radioactive source electroplating solution, a pulse electroplating mode is used to... 63 A Ni radiation source is filled into the intrinsic (I-layer) semiconductor via, with a filling height of approximately 40 μm. Figure 3 As shown in (d), the copper seed layer and the copper metal filling the aforementioned N-type semiconductor vias are dissolved using a copper substrate etching solution (ammonium trichloroacetate solution), leaving only the copper metal filling the intrinsic (I-layer) semiconductor vias. 63 Ni radiation source, the electrically insulating epoxy resin is filled into P-type semiconductor vias and N-type semiconductor vias respectively by drop casting, such as Figure 3 As shown in (e2). Figure 3 As shown in (f2), a 20nm titanium / 200nm aluminum composite metal electrode was sputtered onto the top side of the P-type semiconductor and a 200nm aluminum metal electrode was sputtered onto the back side of the N-type semiconductor, completing the fabrication of the three-dimensional through-hole silicon structure nuclear battery. The performance of the three-dimensional through-hole silicon structure nuclear battery was tested using a Keithley 4200-SCS parameter analyzer, obtaining a maximum output power of approximately 80μW / cm². 3 .

[0065] Example 3

[0066] This embodiment uses a three-dimensional through-hole silicon carbide structure and 3 The nuclear battery based on the H radioactive source and its preparation method are described in detail below:

[0067] Select a 4-inch, 200μm thick N-type substrate (doping concentration ~1×10⁻⁶). 19 cm -3 Using a silicon carbide double-polished wafer as the substrate, a 53 μm thick layer with a doping concentration of 1 × 10⁻⁶ was epitaxially deposited on an N-type single-crystal silicon substrate using plasma-enhanced chemical vapor deposition. 15 cm -3 A lightly doped N-type epitaxial layer (intrinsic I layer) is formed. A layer with a doping concentration of 1×10⁻⁶ is then epitaxially grown on the surface of the lightly doped N-type epitaxial layer. 19 cm -3 The low-doped p-region, approximately 2 μm thick, forms a PIN junction. A three-dimensional PIN junction with a via radius of 2.5 μm and a spacing of 10 μm is obtained through femtosecond laser etching and wet etching. Figure 3As shown in (a) and 3(b), the 4-inch wafer was cut into basic units with an effective area of ​​1cm × 1cm using a laser cutter and then placed in a moisture-proof cabinet for later use.

[0068] After cutting the basic unit, a 5nm copper seed layer is deposited at the bottom of the through-hole 3D PIN junction using magnetron sputtering. The upper part of the through-hole 3D PIN junction is immersed in a molten salt plating solution containing sodium chloride and aluminum chloride. At 200℃, pulse plating is used to fill the N-type semiconductor through-hole with aluminum metal approximately 202μm high. Figure 3 As shown in (c), the upper part of the PIN junction, which has been filled with aluminum metal in the N-type semiconductor via, is re-immersed in an electroplating solution containing palladium metal. Palladium metal is then filled into the intrinsic (I-layer) semiconductor via using a pulse electrodeposition mode, with a filling height of approximately 50 μm. Figure 3 As shown in (d). Utilizing palladium metal adsorption... 3 H, completed 3 The H-ray source is filled in the intrinsic (I-layer) semiconductor via. Simultaneously, the aluminum metal filled in the aforementioned N-type semiconductor via is converted into alumina insulating material using thermal oxidation, while retaining a 5nm copper seed layer. The electrically insulating silicone rubber is then filled into the P-type semiconductor via using a drop-casting method. Figure 3 As shown in (e1). Figure 3 As shown in (f1), a 20nm titanium / 90nm aluminum / 20nm nickel composite electrode and a 500nm nickel metal electrode were finally sputtered onto both the P-type and N-type semiconductors, respectively, to complete the fabrication of the three-dimensional through-hole structure nuclear battery. The performance of the three-dimensional through-hole silicon carbide structure nuclear battery was tested using a Keithley 4200-SCS parameter analyzer, obtaining a maximum output power of approximately 200 μW / cm². 3 .

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A nuclear battery based on a three-dimensional through-hole structure, characterized in that, The nuclear battery structure includes a three-dimensional through-hole PIN junction semiconductor transducer (1), a radiation source (2), and an electrode layer (3); The three-dimensional via PIN junction semiconductor transducer (1) consists of, from top to bottom, a P-type semiconductor layer (11), an intrinsic semiconductor layer (12), and an N-type semiconductor layer (13); the three-dimensional via PIN junction semiconductor transducer is provided with a three-dimensional via array penetrating the P-type semiconductor layer (11), the intrinsic semiconductor layer (12), and the N-type semiconductor layer (13); the three-dimensional via array includes multiple vias, each via penetrating the P-type semiconductor layer (11) is a P-type semiconductor via (14), each via penetrating the intrinsic semiconductor layer (12) is an intrinsic semiconductor via (15), and each via penetrating the N-type semiconductor layer (13) is an N-type semiconductor via (16); the radiation source (2) is filled in the intrinsic semiconductor via (15), and the P-type semiconductor via (14) and N-type semiconductor via (16) are filled with an electrically insulating material (4); The electrode layer includes a top electrode (31) and a back electrode (32), and the three-dimensional through-hole PIN junction semiconductor transducer (1) is sandwiched between the top electrode (31) and the back electrode (32).

2. The method for preparing the three-dimensional through-hole structure nuclear battery according to claim 1, characterized in that, Includes the following steps: S1. After obtaining a PIN junction on a semiconductor substrate by diffusion, ion implantation or epitaxial growth, a three-dimensional through-hole array is etched to obtain a three-dimensional through-hole PIN junction semiconductor transducer (1). S2. Prepare a metal seed layer (5) at the bottom of the three-dimensional through-hole array, and use electroplating to fill the conductive material (6) in the N-type semiconductor through-hole; S3. Based on the sample prepared in step S2, fill the intrinsic semiconductor via with a radioactive source (2), fill the P-type semiconductor via with an electrically insulating material (4), and convert the conductive material (6) filled in step S2 into an electrically insulating material (4) in the N-type semiconductor via while retaining the metal seed layer (5), or remove the metal seed layer (5) and the original conductive material (6) before filling with the electrically insulating material (4). S4. Sputter the top electrode (31) and the back electrode (32) on both sides of the filled P-type and N-type semiconductors respectively to complete the fabrication of the three-dimensional through-hole structure nuclear battery.

3. The preparation method according to claim 2, characterized in that, The material of the three-dimensional through-hole PIN junction semiconductor transducer (1) is one of silicon, gallium arsenide, gallium nitride, silicon carbide, diamond, gallium oxide, boron nitride, aluminum nitride, or wide bandgap semiconductor or ultra-wide bandgap semiconductor.

4. The preparation method according to claim 2, characterized in that, The radioactive source (2) is one of nickel-63, tritium-3, promethium-147 or β radioactive isotope source.

5. The preparation method according to claim 2, characterized in that, The electrode layer (3) is a composite electrode comprising any one or any combination of platinum, gold, silver, aluminum, titanium, nickel, copper, tungsten, germanium, indium and gallium.

6. The preparation method according to claim 2, characterized in that, In step S1, the thickness of the P-type semiconductor layer (11) is 10 nm to 10 μm, and the doping concentration is 10. 17 ~10 20 cm -3 The intrinsic semiconductor layer (12) has a thickness of 5~200 μm and a doping concentration of 10. 12 ~10 17 cm -3 The N-type semiconductor layer (13) has a thickness of 10~800 μm and a doping concentration of 10. 17 ~10 20 cm -3 .

7. The preparation method according to claim 2, characterized in that, In step S1, the etching includes any one or any combination of chemical wet etching, physical dry etching, and laser etching, with the through-hole etching size radius being 100 nm to 20 μm.

8. The preparation method according to claim 2, characterized in that, In step S2, the metal seed layer (5) and the filled conductive material (6) are any one of the following metal materials or alloys or composite metal conductive materials: aluminum, copper, titanium, magnesium, nickel, gold, palladium, platinum and silver. The thickness of the seed layer is 1 nm to 10 nm.

9. The preparation method according to claim 2, characterized in that, In step S3, filling the intrinsic semiconductor via with a radioactive source (2) can be either a solid radioactive source or a gaseous radioactive source. If a solid metal radioactive source is filled, the upper part of the sample prepared in step S2 is immersed in an electroplating solution containing radioactive source particles. By adjusting the electrodeposition parameters, the radioactive source is filled into the intrinsic semiconductor via. If a gaseous radioactive source is filled, based on the sample prepared in step S2, the corresponding gaseous radioactive source metal material or metal compound material is deposited and filled into the intrinsic semiconductor via, and then the gaseous radioactive source is adsorbed and filled.

10. The preparation method according to claim 2, characterized in that, In step S3, the electrically insulating material (4) filling the P-type semiconductor via is any one of oxide insulating material, epoxy resin, silicone rubber, and polyurethane.

11. The preparation method according to claim 2, characterized in that, In step S3, the conductive material (6) filled in step S2 is converted into an electrically insulating material (4) in the N-type semiconductor via while retaining the metal seed layer (5), or the metal seed layer (5) and the original conductive material (6) are removed before filling with the electrically insulating material (4). Specifically, the conductive material (6) filled in step S2 is directly converted into an oxide insulating material by thermal oxidation while retaining the metal seed layer (5), or the metal seed layer (5) and the original conductive material (6) filled inside it are removed by solution etching, and then filled with any one of epoxy resin, silicone rubber, or polyurethane. The filling height of the electrically insulating material (4) in the P-type semiconductor via (14) is 1-10 μm higher than the thickness of the P-type semiconductor layer (11); the filling height of the radioactive source (2) in the intrinsic semiconductor via (15) is 2-20 μm lower than the thickness of the intrinsic semiconductor layer (12); the filling height of the electrically insulating material (4) in the N-type semiconductor via (16) is 1-10 μm higher than the thickness of the N-type semiconductor layer (13).

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