Oxide dielectric passivation layer material and preparation method thereof
By introducing OH trap defects in the HfO2 film, assisting hole carrier tunneling, the problem of the oxide dielectric passivation layer hindering the longitudinal transmission of carriers is solved, and the performance of Si-based devices is significantly improved, especially in the field of solar cells and photodetectors.
Patent Information
- Application Number
- CN202411891918.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-20
- Publication Date
- 2025-03-21
AI Technical Summary
When the existing oxide dielectric passivation layer passivates the interface defects between the Si surface and the Si-based heterojunction, it hinders the longitudinal transmission of carriers and limits the improvement of Si-based device performance.
By introducing OH trap defects into the HfO2 film, the OH trap defects are used to assist hole carrier tunneling to improve the transmission of holes in the HfO2 film, thereby achieving passivation of Si surface defects while ensuring efficient longitudinal transmission of hole carriers.
The performance of Si-based devices has been significantly improved, especially in the field of Si-based solar cells and photodetectors. Compared with the traditional HfO2 dielectric passivation layer, the OH-doped HfO2 dielectric passivation layer increases the photocurrent of the device by more than 10 times.
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Figure CN119677241A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of semiconductors, and in particular relates to an oxide dielectric passivation layer material and a preparation method thereof. Background Art
[0002] Silicon (Si) is a first-generation semiconductor material and an important material for manufacturing microelectronic devices such as diodes and transistors, integrated circuits, and optoelectronic devices such as photodetectors and solar cells. After years of technological precipitation and accumulation, the manufacturing process of Si-based microelectronic and optoelectronic devices is relatively mature, with the advantages of large-scale production and low cost. However, due to surface dangling bonds and lattice mismatch, there are a large number of defects on the Si surface and Si-based heterojunction interface. These defects promote the non-radiative recombination of electron-hole carriers, seriously reducing the performance of Si-based devices. Studies have shown that the use of insulating oxide dielectric layers such as Al2O3 and HfO2 can effectively passivate the defects on the Si surface and Si-based heterojunction interface, thereby improving the performance of the above-mentioned Si-based devices. However, these oxides are insulating materials, which hinder the longitudinal transport of carriers when passivating the defects on the Si surface and Si-based heterojunction interface, which limits the improvement of the performance of Si-based devices to a certain extent. Therefore, it is necessary to modify the oxide dielectric passivation layer to improve the longitudinal transport of carriers and realize the preparation and application of high-performance Si-based devices. Summary of the invention
[0003] In view of some deficiencies of the existing oxide dielectric passivation layer, the present invention provides an oxide dielectric passivation layer material and a preparation method thereof. The present invention introduces OH trap defects in the HfO2 film, utilizes the OH trap defects to assist the tunneling movement of hole carriers, and improves the transmission of holes in the HfO2 film, thereby achieving the result of passivating Si surface defects and ensuring efficient longitudinal transmission of hole carriers. It has important applications in the fields of Si-based solar cells, photodetectors, etc., and has strong industrial applicability.
[0004] The present invention achieves the above technical objectives through the following technical means.
[0005] An oxide dielectric passivation layer material is an OH-doped HfO2 thin film material.
[0006] Preferably, in the OH-doped HfO2 thin film material, the OH impurities are located at the O lattice site in the HfO2 unit cell.
[0007] Preferably, the OH-doped HfO2 thin film material has a thickness of 2 nm to 10 nm.
[0008] A method for preparing an oxide dielectric passivation layer material comprises the following steps:
[0009] (1) Cleaning the Si wafer surface;
[0010] (2) Atomic layer deposition was used to prepare OH-doped HfO2 thin film material on the surface of Si wafer:
[0011] The cleaned Si wafer in step (1) was placed in the reaction chamber of the atomic layer deposition system, water H2O was used as the O source, and tetrakis(dimethylamino)hafnium C8H 24 HfN4 or hafnium tetrachloride HfCl4 is used as Hf source; the growth temperature is 200-300℃; 6N pure nitrogen is used as cleaning gas; the vacuum degree of the growth chamber is 4.6*10 -1 Torr, the nitrogen flow rate is 20sccm, the vacuum pump speed is 1.5-2L / s, the nitrogen cleaning time between the O source and the Hf source is 2s to 10s, and the nitrogen cleaning time between the Hf source and the O source is 20-30s. This is one cycle, and the repeated cycles are 20 to 60.
[0012] Preferably, in step (1), the cleaning step of the Si wafer comprises:
[0013] Step A1, using acetone, anhydrous ethanol and deionized water to ultrasonically clean the Si wafer in sequence to remove stains such as oil stains on the surface of the silicon wafer, and then using nitrogen to dry it;
[0014] Step A2, soaking the Si wafer in hydrofluoric acid to remove the natural oxide layer on the silicon surface;
[0015] Step A3: Clean the silicon wafer with ethanol and deionized water in turn to remove hydrofluoric acid impurities on the surface of the silicon wafer, and then dry it with nitrogen to obtain a clean Si wafer.
[0016] The OH-doped HfO2 thin film material prepared by the invention is used as a passivation layer in Si-based photoelectric detectors and solar cell devices.
[0017] Compared with the prior art, the present invention has the following beneficial effects:
[0018] In the prior art, most academic and industrial circles use insulating oxide dielectric films such as Al2O3 and HfO2 to passivate Si surface and Si-based heterojunction interface defects, inhibit non-radiative recombination caused by defects, and improve the performance of Si-based photodetectors and solar cell devices. Although these oxide dielectric passivation layers can significantly passivate Si surface and Si-based heterojunction interface defects, their insulation hinders the longitudinal transmission of electron-hole carriers, which limits the performance improvement of the above-mentioned Si-based devices to a certain extent.
[0019] The present invention provides a HfO2 dielectric passivation layer containing OH trap defects, wherein the HfO2 material can efficiently passivate Si surface and Si-based heterojunction interface defects, and the OH trap defects can assist hole carrier tunneling movement and enhance the longitudinal transmission of holes in the HfO2 passivation layer. Therefore, the OH-doped HfO2 dielectric passivation layer has the function of efficiently passivating Si surface and Si-based heterojunction interface defects and promoting the longitudinal transmission of hole carriers, overcoming the problem that the traditional insulating HfO2 dielectric passivation layer hinders the longitudinal transmission of carriers. In terms of passivating CH3NH3PbI3 / Si heterojunction interface defects, the OH-doped HfO2 dielectric passivation layer significantly improves the performance of the device. Compared with the traditional HfO2 dielectric passivation layer, the OH-doped HfO2 as a dielectric passivation layer increases the photocurrent of the device by more than 10 times. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is a schematic diagram of OH impurities occupying the O lattice site of HfO2 material;
[0021] Figure 2 This is a schematic diagram of the structure after the OH-doped HfO2 dielectric passivation layer is prepared on the surface of the Si wafer;
[0022] Figure 3 It is a schematic diagram of CH3NH3PbI3 / OH-doped HfO2 / Si heterojunction photodetector;
[0023] Figure 4 This is the atomic force microscopy result of the OH-doped HfO2 dielectric passivation layer;
[0024] Figure 5 It is the X-ray photoelectron spectroscopy result of the OH-doped HfO2 dielectric passivation layer;
[0025] Figure 6 It is the result of the passivation of Si surface defects by the OH-doped HfO2 dielectric passivation layer;
[0026] Figure 7 It is the conduction mechanism of hole carriers in OH-doped HfO2 material;
[0027] Figure 8 This is the result of using OH-doped HfO2 as a dielectric passivation layer to improve the performance of perovskite CH3NH3PbI3 / Si heterojunction photodetectors. DETAILED DESCRIPTION
[0028] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.
[0029] Embodiment 1:
[0030] Take a p-type Si wafer with a thickness of 500 μm and a resistivity of 0.01 Ω·cm and 1-10 Ω·cm, and use acetone and anhydrous ethanol to ultrasonically clean the Si wafer for 5 minutes, then use deionized water to continuously rinse the surface of the Si wafer, and finally use a nitrogen gun to blow dry the Si wafer.
[0031] The Si wafer was immersed in 5% hydrofluoric acid for 1 minute, then immersed in anhydrous ethanol for 5 minutes, and finally the surface of the Si wafer was continuously rinsed with deionized water. Finally, the Si wafer was blown dry with a nitrogen gun to obtain a clean Si wafer without an oxide layer and oil stain.
[0032] The cleaned Si wafer was placed in the reaction chamber of the atomic layer deposition system, and an OH-doped HfO2 dielectric passivation layer was prepared on the surface of the Si wafer. The preparation conditions were as follows: water (H2O) was used as the O source, tetrakis(dimethylamino)hafnium (C8H 24 HfN4) as the Hf source; the growth temperature is 250°C; 6N pure nitrogen is used as the cleaning gas; the nitrogen cleaning time between the O source and the Hf source is 3s, and the nitrogen cleaning time between the Hf source and the O source is 20s. A total of 50 cycles are grown to obtain the following Figure 2 The Si sheet material shown contains an OH-doped HfO2 dielectric passivation layer, wherein the thickness of the OH-doped HfO2 dielectric passivation layer is 8.6 nm.
[0033] like Figure 1 , OH-doped HfO2 thin film material, where the OH impurities are located at the O lattice site in the HfO2 unit cell.
[0034] Further, the perovskite CH3NH3PbI3 film was prepared on the surface of the OH-doped HfO2 dielectric passivation layer by solution spin coating, and Au electrode was deposited on the surface of the CH3NH3PbI3 film, and Ag electrode was prepared on the Si surface to obtain the following Figure 3 The CH3NH3PbI3 / OH-doped HfO2 / Si heterojunction photodetector shown.
[0035] Figure 4 The atomic force microscopy results of the OH-doped HfO2 dielectric passivation layer are shown. It can be seen that the surface of the OH-doped HfO2 dielectric passivation layer is smooth, and the root mean square value of the surface roughness is 0.30nm, which has the ability to uniformly passivate Si surface defects.
[0036] Figure 5 The X-ray photoelectron spectroscopy results of the 1s orbital core-level of O atoms in the OH-doped HfO2 dielectric passivation layer are shown. It can be seen that the prepared HfO2 material has a high concentration of OH impurities.
[0037] Figure 6 The results of the transient photoconductivity method for measuring the carrier lifetime on the Si surface show that the OH-doped HfO2 dielectric layer can significantly passivate the surface defects of Si. Under the passivation effect of the OH-doped HfO2 dielectric layer, the minority carrier lifetime on the Si surface increases from 5.2μs to 19.7μs.
[0038] Figure 7 The volt-ampere characteristic curves of Au / traditional HfO2 dielectric layer / Si and Au / OH-doped HfO2 dielectric layer / Si structure devices are shown. The analysis shows that the conduction mechanism of holes in the traditional HfO2 dielectric layer is thermal electron emission, while the conduction mechanism of holes in the OH-doped HfO2 dielectric layer is Fowler-Nordheim tunneling, that is, tunneling motion assisted by OH trap defects. Under 1V bias, the leakage current of the traditional HfO2 passivation layer is 0.2nA, while the leakage current of the OH-doped HfO2 passivation layer is 5.6nA.
[0039] Figure 8 The results of the CH3NH3PbI3 / Si heterojunction photodetector performance are shown. It can be seen that compared with the traditional HfO2 dielectric passivation layer, the OH-doped HfO2 as a dielectric passivation layer increases the photocurrent of the device by more than 10 times. The photocurrent of the CH3NH3PbI3 / Si heterojunction photodetector under the passivation of the traditional HfO2 dielectric layer is 0.15nA, while the photocurrent of the device under the passivation of the OH-doped HfO2 dielectric layer increases to 1.65nA.
[0040] Embodiment 2:
[0041] Take a p-type Si wafer with a thickness of 500 μm and a resistivity of 1-10 Ω·cm, and use acetone and anhydrous ethanol to ultrasonically clean the Si wafer for 5 minutes, then rinse the surface of the Si wafer with deionized water, and finally use a nitrogen gun to blow dry the Si wafer.
[0042] The Si wafer was immersed in 5% hydrofluoric acid for 1 minute, then immersed in anhydrous ethanol for 5 minutes, and finally rinsed with deionized water. Finally, the Si wafer was dried with a nitrogen gun to obtain a clean Si wafer without an oxide layer and oil stain.
[0043] The cleaned Si wafer was placed in the reaction chamber of the atomic layer deposition system, and an OH-doped HfO2 dielectric passivation layer was prepared on the surface of the Si wafer. The preparation conditions were as follows: water (H2O) was used as the O source, tetrakis(dimethylamino)hafnium (C8H 24HfN4) is used as the Hf source; the growth temperature is 225°C; 6N purity nitrogen is used as the cleaning gas; the nitrogen cleaning time between the O source and the Hf source is 5s, and the nitrogen cleaning time between the Hf source and the O source is 20s, and a total of 50 growth cycles are performed to prepare an OH-doped HfO2 dielectric passivation layer material on the surface of the Si wafer, wherein the thickness of the OH-doped HfO2 dielectric passivation layer is 7.7nm.
[0044] Embodiment 3:
[0045] Take a p-type Si wafer with a thickness of 500 μm and a resistivity of 1 Ω·cm, and use acetone and anhydrous ethanol to ultrasonically clean the Si wafer for 5 minutes, then use deionized water to continuously rinse the surface of the Si wafer, and finally use a nitrogen gun to blow dry the Si wafer.
[0046] The Si wafer was immersed in 5% hydrofluoric acid for 1 minute, then immersed in anhydrous ethanol for 5 minutes, and finally rinsed with deionized water. Finally, the Si wafer was dried with a nitrogen gun to obtain a clean Si wafer without an oxide layer and oil stain.
[0047] The cleaned Si wafer was placed in the reaction chamber of the atomic layer deposition system, and an OH-doped HfO2 dielectric passivation layer was prepared on the surface of the Si wafer. The preparation conditions were as follows: water (H2O) was used as the O source, tetrakis(dimethylamino)hafnium (C8H 24 HfN4) was used as the Hf source; the growth temperature was 275°C; 6N purity nitrogen was used as the cleaning gas; the nitrogen cleaning time between the O source and the Hf source was 2.5s, and the nitrogen cleaning time between the Hf source and the O source was 20s, and a total of 50 growth cycles were performed to prepare an OH-doped HfO2 dielectric passivation layer material on the surface of the Si wafer, wherein the thickness of the OH-doped HfO2 dielectric passivation layer was 6.5nm.
[0048] Embodiment 4:
[0049] Take a p-type Si wafer with a thickness of 500 μm and a resistivity of 1-10 Ω·cm, and use acetone and anhydrous ethanol to ultrasonically clean the Si wafer for 5 minutes, then rinse the surface of the Si wafer with deionized water, and finally use a nitrogen gun to blow dry the Si wafer.
[0050] The Si wafer was immersed in 5% hydrofluoric acid for 1 minute, then immersed in anhydrous ethanol for 5 minutes, and finally rinsed with deionized water. Finally, the Si wafer was dried with a nitrogen gun to obtain a clean Si wafer without an oxide layer and oil stain.
[0051] The cleaned Si wafer was placed in the reaction chamber of the atomic layer deposition system, and an OH-doped HfO2 dielectric passivation layer was prepared on the surface of the Si wafer. The preparation conditions were as follows: water (H2O) was used as the O source, tetrakis(dimethylamino)hafnium (C8H 24 HfN4) is used as the Hf source; the growth temperature is 300°C; 6N purity nitrogen is used as the cleaning gas; the nitrogen cleaning time between the O source and the Hf source is 2s, and the nitrogen cleaning time between the Hf source and the O source is 20s, and a total of 50 growth cycles are performed to prepare an OH-doped HfO2 dielectric passivation layer material on the surface of the Si wafer, wherein the thickness of the OH-doped HfO2 dielectric passivation layer is 5.0nm.
[0052] Embodiment 5:
[0053] Take a p-type Si wafer with a thickness of 500 μm and a resistivity of 1-10 Ω·cm, and use acetone and anhydrous ethanol to ultrasonically clean the Si wafer for 5 minutes, then rinse the surface of the Si wafer with deionized water, and finally use a nitrogen gun to blow dry the Si wafer.
[0054] The Si wafer was immersed in 5% hydrofluoric acid for 1 minute, then immersed in anhydrous ethanol for 5 minutes, and finally rinsed with deionized water. Finally, the Si wafer was dried with a nitrogen gun to obtain a clean Si wafer without an oxide layer and oil stain.
[0055] The cleaned Si wafer was placed in the reaction chamber of the atomic layer deposition system, and an OH-doped HfO2 dielectric passivation layer was prepared on the surface of the Si wafer. The preparation conditions were as follows: water (H2O) was used as the O source, and hafnium tetrachloride was used as the Hf source; the growth temperature was 300°C; 6N purity nitrogen was used as the cleaning gas; the nitrogen cleaning time between the O source and the Hf source was 2s, and the nitrogen cleaning time between the Hf source and the O source was 20s. A total of 50 cycles were grown to prepare an OH-doped HfO2 dielectric passivation layer material on the surface of the Si wafer, wherein the thickness of the OH-doped HfO2 dielectric passivation layer was 5.0nm.
[0056] The embodiments are preferred implementations of the present invention, but the present invention is not limited to the above-mentioned implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essential content of the present invention belong to the protection scope of the present invention.
Claims
1. An oxide dielectric passivation layer material, characterized in that: It is an OH-doped HfO2 thin film material, specifically, the OH impurities are located at the O lattice site in the HfO2 unit cell.
2. The oxide dielectric passivation layer material according to claim 1, characterized in that: The thickness is 2nm to 10nm.
3. The method for preparing the oxide dielectric passivation layer material according to any one of claims 1 to 2, characterized in that: The following steps are involved: (1) Cleaning the surface of Si wafer; (2) Atomic layer deposition was used to prepare OH-doped HfO2 thin film material on the surface of Si wafer: The cleaned Si wafer in step (1) was placed in the reaction chamber of the atomic layer deposition system, water H2O was used as the O source, and tetrakis(dimethylamino)hafnium C8H 24 HfN4 or hafnium tetrachloride HfCl4 is used as the Hf source; the growth temperature and vacuum degree are set; 6N purity nitrogen is used as the cleaning gas; the nitrogen cleaning time between the O source and the Hf source is 2s to 10s, and the nitrogen cleaning time between the Hf source and the O source is 20 to 30s, which is one cycle, and it is repeated several times.
4. The preparation method according to claim 3, characterized in that: In step (2), the growth temperature is 200-300°C.
5. The preparation method according to claim 3, characterized in that: In step (2), the vacuum degree of the growth chamber is 4.6*10 - 1 Torr, vacuum pump speed is 1.5~2L / s.
6. The preparation method according to claim 3, characterized in that: In step (2), the nitrogen flow rate is 20 sccm.
7. The preparation method according to claim 3, characterized in that: In step (2), the number of repetition cycles is 20 to 60.
8. Use of the oxide dielectric passivation layer material according to claim 1 as a passivation layer in Si-based photodetectors and solar cell devices.