Anti-ultraviolet attenuation isolating membrane layer structure and preparation method thereof
By designing an ultraviolet attenuation-resistant isolation film layer structure between the composite silicon nitride layer and the alumina layer of the TOPCon solar cell, the stacked structure of SiO2 and SiOxNy layers is used to solve the problem of battery performance attenuation under ultraviolet irradiation, and better anti-ultraviolet ability and passivation effect are achieved.
Patent Information
- Application Number
- CN202510125148.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-27
- Publication Date
- 2025-05-30
AI Technical Summary
TOPCon solar cells have attenuation problems under ultraviolet irradiation, mainly because the alumina film layer is easily damaged, resulting in silicon-hydrogen bond fracture and hydrogen atom cluster accumulation, affecting battery performance.
A resistant isolation film layer structure is designed, located between the composite silicon nitride layer and the alumina layer. By depositing SiO2 and SiOxNy layers in the SiNx layer, a composite laminate film layer with a structure of 2+1+1 is formed to enhance the passivation effect of the battery.
It effectively reduces the attenuation of battery performance under ultraviolet irradiation, improves the battery's UV resistance, and has simple process conditions and low cost.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of photovoltaic technology, and specifically relates to an anti-ultraviolet attenuation isolation film layer structure and a preparation method thereof. Background Art
[0002] Under the background of the global energy transformation, the photovoltaic industry has become an important force in promoting sustainable development due to its advantage of clean energy. As a new generation of technology representative in the photovoltaic field, TOPCon cells were once highly anticipated due to the advantages of N-type monocrystalline passivated contact cells such as high efficiency, long life, no LID, good low-light response, and high ultimate efficiency. However, with the expansion of its application, the problem of ultraviolet attenuation has gradually emerged and attracted widespread attention. Ultraviolet attenuation is related to the redistribution of hydrogen in the cell. After ultraviolet irradiation, the hydrogen concentration near the passivation interface and the silicon substrate is relatively high. The hydrogen bond breakage on the cell surface leads to an excess of hydrogen atom clusters, which promotes carrier recombination and reduces the cell performance. Compared with traditional cell wafers, the attenuation amplitude of high-efficiency cells is larger, and the attenuation amplitude of the back side of bifacial cells is larger. For different structural cells, the corresponding electrical performance attenuation mechanisms are different. P-type cells use phosphorus diffusion, with excellent diffusion effect and good passivation effect. Even if the alumina is damaged to some extent, the impact on attenuation is relatively limited. However, N-type cells use boron diffusion, and the solid solubility of boron is not good, resulting in poor passivation effect, and rely on silicon nitride and alumina for passivation. Currently, the alumina film layer is easily penetrated and damaged by ultraviolet rays, further damaging some silicon-hydrogen bonds, causing H atoms to accumulate at the interface and destroying passivation, resulting in a more prominent attenuation problem. Even the traditional Al 2 O 3 / SiNx stack structure still cannot avoid this attenuation. Although UV improvement can start from the encapsulation materials at the module end, the module cost is high.
[0003] Therefore, starting from the cell passivation process, designing an anti-ultraviolet attenuation isolation film layer structure between the composite silicon nitride layer and the alumina layer to enhance the self-passivation of the cell is an urgent problem to be solved by those skilled in the art. Summary of the Invention
[0004] Based on the above situation, in order to overcome the deficiencies of the prior art, the present invention provides an anti-ultraviolet attenuation isolation film layer structure with strong operability, simple process conditions, low cost, and effectiveness, and a preparation method thereof.
[0005] The technical implementation solution of the present invention is as follows: The isolation film layer structure is located between the bottom layer of the composite silicon nitride layer and the alumina layer. The isolation film layer structure is formed by inserting a silicon wafer with a dense alumina layer formed into a graphite boat, and after preheating treatment, passing an electric current and introducing a gas for a certain period of time to form a thin-layer composite isolation film layer.
[0006] An anti-ultraviolet attenuation isolation film layer structure includes an N-type silicon substrate wafer, on the surface of which are successively arranged a boron-doped emitter, an alumina layer, a first isolation dielectric film layer, a second isolation dielectric film layer, and a composite laminate film layer.
[0007] Preferably, it is characterized in that the first dielectric isolation film layer is a SiO 2 layer, formed in an atmosphere of SiH 4 and N 2 O, and the film-forming thickness is controlled within 2 - 10 nm.
[0008] Preferably, the second dielectric isolation film layer is a SiOxNy layer, formed in an atmosphere of SiH 4 , N 2 O, NH 3 atmosphere, and the thickness is controlled within 2 - 10 nm.
[0009] Preferably, the composite laminate film layer has a 2 + 1 + 1 structure, including two layers of SiNx, one layer of SiOxNy, and one layer of SiO 2 .
[0010] A preparation method of an anti-ultraviolet attenuation isolation film layer structure includes the following steps: Select an N-type silicon substrate wafer that has undergone a conventional pretreatment process, use a PECVD tube furnace to prepare the first isolation dielectric film layer, then deposit the second isolation film layer on the first isolation dielectric film layer, and then deposit the composite laminate film layer. The cell wafer then undergoes subsequent processes to form a finished cell wafer.
[0011] Preferably, the pretreatment of the N-type silicon substrate wafer includes forming a textured surface by texturing, boron diffusion, oxidation, LP / PE-Poly, removing the front and back phosphorus-silicon glass and borosilicate glass, and forming a dense Al 2 O 3 layer on the front surface.
[0012] Preferably, the dense Al 2 O 3 film layer formed on the front surface has a thickness controlled within 4 - 9 nm.
[0013] Preferably, the subsequent processes include preparing the back film layer, front and back metallization, sintering, light injection annealing, and laser induction.
[0014] Compared with the prior art, the advantages of the present invention are as follows: Aiming at the problem that in the existing passivation technology, UV exposure will cause the Si-H bonds in the TOPCon solar cell to break, the bulk hydrogen content to decrease significantly, the void density to increase, and the interfacial hydrogen to accumulate, thus introducing more defects on the surface, resulting in the deterioration of surface passivation and causing component attenuation. The present invention optimizes the ALD-deposited alumina film layer and the SiNx laminate structure through process design of the isolation film layer at the cell end to further enhance the self-passivation of the cell. Al 2O 3 The interface between the amorphous dielectric film and silicon has a high concentration of negative charges, which can achieve good passivation effects on both p- and n-type surfaces. A large number of positive charges are contained in SiNx, and an inversion layer is generated when deposited on the front surface n-type emitter, which is more conducive to the surface passivation of the n-layer. However, Al 2 O 3 / SiNx has negative surface fixed charges, indicating that positive charges are generated when SiNx is in direct contact with Si. There is strong tensile stress on the Si surface of SiNx. Although hydrogen atoms can diffuse to the Si-SiN interface and effectively passivate the interface states, its interface quality is inferior to that of Si-SiO 2 . Therefore, in this design, to ensure high interface quality, the thickness and density of the Al 2 O 3 film layer need to be strictly controlled. Usually, the SiO 2 film layer prepared by PECVD is porous and loose, containing a large density of O-H, N-O, and Si-H bonds, which can affect the stability and optical properties (refractive index and infrared absorption) of the film layer. For example, the absorption peaks of Si-H and O-H at wavelengths of 630 and 1400 nm increase the loss of the film layer. However, annealing treatment in an N 2 atmosphere can eliminate H bonds and residual stress, making the film layer densified. The annealing treatment temperature and time have a certain impact on the film layer performance. Usually, the O-H absorption disappears after annealing at 800 °C, while the absorption of N-H and Si-H needs to be annealed at 1100 °C to weaken, accompanied by a significant reduction in loss. Therefore, the control of the interface quality (thickness and density) of the single-layer SiO 2 isolation film layer and the passivation effect of interface charge accumulation are insufficient. The SiOxNy (hereinafter referred to as SiON) thin film is an intermediate phase between silicon dioxide and silicon nitride, with excellent passivation and antireflection characteristics. By changing the component ratio, its refractive index can be adjusted within a certain range (1.45 - 2.3), making the SiON thin film have antireflection performance. At the same time, SiON also contains a large number of hydrogen atoms, and good passivation effects can also be achieved. The presence of oxygen may enable SiON to obtain better interface quality and a faster production rate on the silicon surface. This design cleverly combines the characteristics of the two passivation thin films to form a high-quality isolation film layer interface between the Al 2 O 3 and SiNx laminated structure. The accumulation of negative charges at the interface forms a strong built-in electric field, enhancing the field passivation effect. At the same time, the traditional chemical passivation method of using H atoms to eliminate the dangling bonds on the silicon surface is changed, and O is used to reduce the dangling bonds, enhance the chemical bond energy, and avoid the passivation failure caused by the accumulation of H at the interface under ultraviolet irradiation. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 FIG. is a schematic diagram of the front film layer structure of the anti-ultraviolet attenuation solar cell provided by the embodiment of the present invention; Figure 2 Flow chart of the preparation method of the front film layer structure of the anti-ultraviolet attenuation solar cell provided by the embodiment of the present invention; Figure 3 UV30 power test charts of Embodiment 1, Embodiment 2, Embodiment 3 and the comparative example of the present invention. Detailed implementation manners
[0016] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It is hereby declared that the orientation terms such as up, down, left, right, front, back, inside and outside that appear or will appear in the text of the present invention are only based on the accompanying drawings of the present invention, and they do not specifically limit the present invention. Embodiment
[0017] An anti-ultraviolet attenuation isolation film layer structure and its preparation method include the following specific steps: Select an N-type silicon substrate wafer that has undergone a conventional pretreatment process, use a PECVD tube furnace to prepare the first isolation dielectric film layer, then deposit a second isolation film layer on the first isolation dielectric film layer, and then deposit a composite laminated film layer. The battery wafer then undergoes subsequent processes to form a finished battery wafer.
[0018] The first dielectric isolation film layer described in the step is a SiO 2 layer, formed in an atmosphere of SiH 4 and N 2 O, with the thickness controlled at 3 nm; The second dielectric isolation film layer described in the step is a SiOxNy layer, formed in an atmosphere of SiH 4 , N 2 O, NH 3 atmosphere, with the thickness controlled at 2 nm; The composite laminated film layer described in the step has a 2+1+1 structure, including two layers of SiNx, one layer of SiOxNy, and one layer of SiO 2 ; The pretreatment of the N-type silicon substrate wafer described in the step includes texture surface construction, boron diffusion, oxidation, LP / PE-Poly, removal of front and back phosphosilicate glass and borosilicate glass, and formation of a dense Al 2 O 3 layer on the front surface; The dense Al 2 O 3 film layer formed on the front surface has a thickness controlled at 9 nm; The subsequent processes described in the step include back film layer preparation, front and back metallization, sintering, photo-injection annealing, and laser induction. Embodiment
[0019] An anti-ultraviolet attenuation isolation film layer structure and its preparation method, comprising the following specific steps: Select an N-type silicon substrate wafer that has undergone a conventional pretreatment process, use a PECVD tube furnace to prepare the first isolation dielectric film layer, then deposit a second isolation film layer on the first isolation dielectric film layer, and then deposit a composite laminated film layer. The battery wafer then undergoes subsequent processes to form a finished battery wafer.
[0020] The first dielectric isolation film layer described in the step is SiO 2 layer, formed in an atmosphere of SiH 4 and N 2 O, with the thickness controlled at 2 nm; The second dielectric isolation film layer described in the step is SiOxNy layer, formed in an atmosphere of SiH 4 、N 2 O、NH 3 atmosphere, with the thickness controlled at 6 nm; The composite laminated film layer described in the step has a 2+1+1 structure, including two layers of SiNx, one layer of SiOxNy, and one layer of SiO 2 ; The pretreatment of the N-type silicon substrate wafer described in the step includes texture surface construction, boron diffusion, oxidation, LP / PE-Poly, removal of front and back phosphorus-silicon glass and borosilicate glass, and formation of a dense Al 2 O 3 layer on the front surface; The dense Al 2 O 3 film layer formed on the front surface, with the thickness controlled at 6 nm; The subsequent processes described in the step include back film layer preparation, front and back metallization, sintering, light injection annealing, and laser induction. Example
[0021] An anti-ultraviolet attenuation isolation film layer structure and its preparation method, comprising the following specific steps: Select an N-type silicon substrate wafer that has undergone a conventional pretreatment process, use a PECVD tube furnace to prepare the first isolation dielectric film layer, then deposit a second isolation film layer on the first isolation dielectric film layer, and then deposit a composite laminated film layer. The battery wafer then undergoes subsequent processes to form a finished battery wafer.
[0022] The first dielectric isolation film layer described in the step is SiO 2 layer, formed in an atmosphere of SiH 4 and N 2 O, with the thickness controlled at 4 nm; The second dielectric isolation film layer described in the step is SiOxNy layer, formed in an atmosphere of SiH 4 、N 2 O、NH 3Formed in an atmosphere with a thickness controlled at 3 nm; The composite laminated film layer described in the step is a 2 + 1 + 1 structure, including two layers of SiNx, one layer of SiOxNy, and one layer of SiO 2 ; The pretreatment of the N-type silicon substrate wafer described in the step includes texture surface construction, boron diffusion, oxidation, LP / PE-Poly, removal of phosphosilicate glass and borosilicate glass on the front and back sides, and formation of a dense Al 2 O 3 layer on the front surface; The dense Al formed on the front surface described in the step 2 O 3 film layer with a thickness controlled at 7 nm; The subsequent processes described in the step include back film layer preparation, front and back surface metallization, sintering, light injection annealing, and laser induction.
[0023] Comparative example The comparative example adopts the existing preparation method of solar cells, including the following steps: Select an N-type silicon substrate wafer that has undergone conventional pretreatment processes, use a PECVD tube furnace to prepare a composite laminated film, the composite laminated film layer includes a silicon nitride layer + a silicon oxynitride layer + a silicon oxide layer, and the cell wafer is then subjected to subsequent processes to form a finished cell wafer.
[0024] As Figure 3 shown, it is a comparison of the test QE of the silicon wafers obtained in Example 1, Example 2, Example 3 and the comparative example. The abscissa represents the incident light wavelength, and the ordinate represents the ratio of generated electrons / incident photons. It can be seen from the figure that the QE of Example 1 of the present invention has a better short-wave response compared with the comparative example of the existing technology, indicating that the absorption efficiency on the cell surface is high, and the surface recombination loss is less, and the surface passivation effect is good.
[0025] As shown in Table 1, it is a comparison of the UV30 test results of the components prepared from the cells obtained in Example 1 and the comparative example. It can be seen from the table that the power attenuation of Example 1 of the present invention under ultraviolet light is 0.09% compared with the comparative example of the existing technology, indicating that its anti-ultraviolet attenuation property is better.
[0026] Table 1 Comparison of UV30 power tests between Example 1 and the comparative example Example 1 Comparative example Before testing 630.44 W 590.09 W After testing 627.89 W 580.29 W Power attenuation 0.09% 1.66% The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the gist of the present invention.
Claims
1. An anti-ultraviolet attenuation isolation film layer structure, comprising an N-type silicon substrate sheet, characterized in that: The surface of the N-type silicon substrate is sequentially provided with a boron-doped emitter, an aluminum oxide layer, a first isolation dielectric film layer, a second isolation dielectric film layer and a composite laminated film layer.
2. The anti-ultraviolet attenuation isolation film structure according to claim 1 is characterized in that: The first dielectric isolation film layer is a SiO2 layer, which is formed in a SiH4 and N2O atmosphere, and the film thickness is controlled to be 2-10 nm.
3. The anti-ultraviolet attenuation isolation film layer structure according to claim 1, characterized in that: The second dielectric isolation film layer is a SiOxNy layer, which is formed in a SiH4, N2O, and NH3 atmosphere, and has a thickness controlled at 2 to 10 nm.
4. The anti-ultraviolet attenuation isolation film layer structure according to claim 1, characterized in that: The composite laminated film layer is a 2+1+1 structure, including two layers of SiNx, one layer of SiOxNy, and one layer of SiO2.
5. A method for preparing an anti-ultraviolet attenuation isolation film layer structure according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: selecting an N-type silicon substrate sheet that has undergone conventional pretreatment technology, using a PECVD tube furnace to prepare a first isolation dielectric film layer, then depositing a second isolation film layer on the first isolation dielectric film layer, and then depositing a composite laminated film layer. The battery cell then undergoes subsequent processes to form a finished battery cell.
6. The method for preparing an anti-ultraviolet attenuation isolation film structure according to claim 5, characterized in that: The pre-treatment of N-type silicon substrate includes textured surface construction, boron diffusion, oxidation, LP / PE-Poly, removal of front and back phosphosilicate glass and borosilicate glass, and formation of a dense Al2O3 layer on the front surface.
7. The method for preparing an anti-ultraviolet attenuation isolation film layer structure according to claim 6, characterized in that: The thickness of the dense Al2O3 film layer formed on the front surface is controlled to be 4-9 nm.
8. The method for preparing an anti-ultraviolet attenuation isolation film layer structure according to claim 5, characterized in that: The subsequent processes include back film preparation, front and back metallization, sintering, light injection annealing, and laser induction.