Transparent stacked passivation film structure, and preparation method therefor and use thereof

Abstract

A transparent stacked passivation film structure, and a preparation method therefor and the use thereof. The transparent stacked passivation film structure comprises a first passivation layer, a second passivation layer and a third passivation layer, which are sequentially stacked on a surface of a silicon substrate, wherein the first passivation layer is made of a hydrogenated silicon oxide film; the second passivation layer is made of one selected from a hydrogenated silicon carbonitride film, a hydrogenated silicon carbide film, a hydrogenated silicon nitride film, a hydrogenated silicon carboxynitride film, a hydrogenated silicon oxycarbide film and a hydrogenated silicon oxynitride film; and the third passivation layer is made of one or a stacked film of more selected from a hydrogenated aluminum oxide film, a hydrogenated silicon nitride film and a hydrogenated silicon oxide film. The transparent stacked passivation film structure has good surface passivation and bulk passivation effects, can substantially reduce a saturation current density on a surface of a silicon wafer and prolong the bulk lifetime of the silicon wafer, and is beneficial for improving the performance of a silicon-based semiconductor device.

Description

A transparent laminated passivation film structure and its preparation method and application Technical Field

[0001] The present invention relates to the technical field of surface passivation of silicon-based semiconductor devices, and in particular to a transparent laminated passivation film structure, a preparation method thereof, and applications thereof. Background Art

[0002] Surface passivation is a key factor in improving the performance of silicon-based semiconductor devices. For solar cell devices, surface passivation is the most important factor in improving their photoelectric conversion efficiency. Every improvement in solar cell conversion efficiency actually depends on the improvement of the passivation quality of the passivation film surface. For example, the efficiency of p-type passivated emitter and back contact (PERC) solar cells is higher than that of p-type aluminum back surface field (Al-BSF) solar cells because of the use of AlO x / SiN x or SiO x N y The thin film passivates the back surface of the silicon wafer, significantly reducing carrier recombination on the back surface.

[0003] Saturation current density (J0) and implicit open circuit voltage (iV oc ) is a physical quantity that characterizes surface recombination, J0 characterizes the size of surface recombination, and the smaller the value, the lower the surface recombination; iV oc Unlike J0, iV oc Can simultaneously reflect the characterization of surface and bulk complexes, iV oc The higher the value, the lower the surface and bulk recombination. The saturation current density of the passivation film on different silicon wafers will change with the change of the silicon wafer resistivity.

[0004] Currently, common passivation films for silicon solar cell technology include: AlOx / SiNx, SiOx / SiNx, SiOx / SiNx / SiOx, ia-Si:H (or i-μc-Si:H), etc. AlOx / SiNx stacked passivation films are commonly used on PERC cells, and the optimal passivation index on non-diffused p-type or n-type silicon wafers is approximately 2fA / cm 2 SiOx / SiNx and SiOx / SiNx / SiOx are commonly used on phosphorus diffused emitters. Among them, the passivation effect of SiOx / SiNx / SiOx is better than that of SiOx / SiNx. The optimal passivation index of SiOx / SiNx / SiOx on non-diffused n-type planar silicon wafers is ~1fA / cm 2 (High-resistance silicon wafer, resistivity ~90Ωcm) and 4.7fA / cm 2 (Industrial low-resistance silicon wafer, resistivity ~3Ωcm); the optimal passivation index on the diffusion-free n-type random textured silicon wafer is ~3fA / cm 2(High-resistance silicon wafer, resistivity ~90Ωcm). ia-Si:H (or i-μc-Si:H) has the best passivation performance, with the optimal passivation index on non-diffused n-type or p-type silicon wafers being ~0.5fA / cm 2 (Industrial low-resistance silicon wafer, resistivity ~1Ωcm), however, its parasitic absorption is relatively serious.

[0005] In general, the passivation quality of the passivation film is the key factor restricting the improvement of Voc of crystalline silicon solar cells. How to further improve the passivation quality and reduce the saturation current density value is the key to improving the efficiency of silicon solar cells. Summary of the Invention

[0006] The purpose of the present invention is to develop a new surface passivation structure to reduce the saturation current density of silicon wafers and improve the passivation quality of silicon-based semiconductor devices.

[0007] To achieve the above-mentioned objectives, the first aspect of the present invention provides a transparent stacked passivation film structure, comprising a first passivation layer, a second passivation layer and a third passivation layer stacked in sequence on the surface of a silicon substrate, wherein the material of the first passivation layer is a hydrogenated silicon oxide film, the material of the second passivation layer is selected from one of a hydrogenated carbon silicon nitride film, a hydrogenated carbon silicon film, a hydrogenated silicon nitride film, a hydrogenated carbon nitride silicon oxide film, a hydrogenated carbon oxysilicon film and a hydrogenated silicon oxynitride film, and the material of the third passivation layer is selected from one or more stacked films of a hydrogenated aluminum oxide film, a hydrogenated silicon nitride film and a hydrogenated silicon oxide film.

[0008] The transparent laminated passivation film structure of the present invention has excellent surface passivation and body passivation effects, which can significantly reduce the surface of the silicon wafer and increase the life of the silicon wafer. The saturation current density on the silicon wafer surface can be as low as 0.2fA / cm 2 , which is significantly superior to various passivation film structures in the existing technology and can increase the body life of mainstream n-type silicon wafers (1~7Ωcm) in the market to more than 15ms.

[0009] Furthermore, the silicon substrate contains hydrogen, carbon and / or nitrogen, and the concentration of each element gradually decreases from the surface to the body.

[0010] Furthermore, the hydrogen concentration on the surface of the silicon substrate is 1×10 19 cm -3 ~1×10 21 cm -3 Carbon and nitrogen atoms can effectively capture hydrogen atoms and inject them into the substrate and interface to passivate more defect states.

[0011] Furthermore, the nitrogen concentration on the surface of the substrate is 1×10 19 cm -3 ~1×10 22 cm-3 , and / or carbon concentration is 1×10 19 cm -3 ~1×10 22 cm -3 Introducing elements such as carbon, nitrogen, and oxygen near the surface of silicon wafers can improve the mechanical properties of silicon wafers.

[0012] Furthermore, the hydrogen concentration of the first passivation layer is 1×10 19 cm -3 ~1×10 22 cm -3 The hydrogen concentration of the second passivation layer is 1×10 19 cm -3 ~1×10 22 cm -3 , the hydrogen concentration of the third passivation layer is 1×10 19 cm - 3 ~1×10 22 cm -3 Each passivation layer has a high hydrogen concentration and good chemical stability, which can achieve excellent surface protection for silicon wafers.

[0013] Furthermore, the refractive index of the second passivation layer is 1.0 to 5.0. The refractive index of the second passivation layer can be controlled by adjusting the composition.

[0014] Furthermore, the transmittance of the first passivation layer above 400nm is greater than 97%, and the transmittance of the second passivation layer above 400nm is greater than 97%. The transparent stacked passivation film structure has extremely low absorption at wavelengths above 400nm and has extremely low optical absorption characteristics.

[0015] Furthermore, the thickness of the first passivation layer is 1 to 20 nm, preferably 1 to 5 nm, and the thickness of the second passivation layer is greater than or equal to 2 nm, preferably 3 to 100 nm.

[0016] The transparent laminated passivation film structure of the present invention can realize controllable adjustment of optical absorption and transmission characteristics by adjusting the refractive index and film thickness of the second passivation layer.

[0017] A second aspect of the present invention provides a method for preparing the transparent laminated passivation film structure, comprising the following steps:

[0018] S1, cleaning silicon substrate;

[0019] S2, preparing a silicon oxide film on the surface of the silicon substrate;

[0020] S3, depositing an amorphous silicon film containing carbon and / or nitrogen elements on the silicon oxide film;

[0021] S4, performing a high temperature annealing treatment at a temperature of 600° C. to 1200° C. to convert the amorphous silicon thin film into a polycrystalline silicon thin film;

[0022] S5, depositing one or more stacked films of aluminum oxide, silicon nitride, and silicon oxide on the polysilicon film;

[0023] S6. Perform hydrogen injection treatment.

[0024] The preparation method of the transparent laminated passivation film structure of the present invention is fully compatible with existing battery production line technology and has good mass production application prospects. The passivation film structure has good thermal stability, and its passivation quality is not affected by temperature within a temperature range not exceeding 500°C.

[0025] Furthermore, step S6 adopts annealing hydrogenation treatment, the treatment temperature is 300°C to 1000°C, and the protective atmosphere contains inert gas such as nitrogen, preferably a mixture of nitrogen and hydrogen. The hydrogen injection is preferably FGA treatment, and the sintering process can also achieve hydrogen injection.

[0026] Furthermore, in step S3, PECVD is used to in-situ deposit an amorphous silicon film containing carbon and / or nitrogen elements. The second passivation layer introduces carbon and nitrogen atoms into the amorphous silicon film, and the high-temperature annealing treatment can push the carbon and nitrogen atoms into the silicon substrate, thereby improving the mechanical properties of the silicon wafer.

[0027] A third aspect of the present invention provides a silicon-based semiconductor device comprising the transparent laminated passivation film structure described above. The transparent laminated passivation film structure can improve the passivation quality of the silicon-based semiconductor device, significantly reduce its saturation current density, and thus improve device performance.

[0028] In summary, the present invention has the following beneficial effects compared to the prior art:

[0029] (1) The transparent laminated passivation film structure of the present invention has excellent surface passivation effect and body passivation effect, and can reduce the saturation current density on the silicon wafer surface to 0.2fA / cm 2 , which can increase the life of mainstream n-type silicon wafers in the market to more than 15ms.

[0030] (2) The transparent laminated passivation film structure of the present invention has extremely low optical absorption characteristics, and the absorption at wavelengths above 400 nm is extremely low. The optical absorption and transmittance characteristics can be controlled by adjusting the refractive index of the second passivation layer, the film thickness, etc.

[0031] (3) The transparent laminated passivation film structure of the present invention has good chemical stability and thermal stability. The passivation film structure contains elements such as silicon, nitrogen, carbon, and oxygen, which can achieve excellent surface protection for silicon wafers. In the temperature range below 500°C, its passivation quality is not affected by temperature.

[0032] (4) The transparent laminated passivation film structure of the present invention can introduce elements such as carbon, nitrogen, and oxygen into the near-surface of the silicon wafer, which is beneficial to improving the mechanical properties of the silicon wafer.

[0033] (5) The preparation method of the transparent laminated passivation film structure of the present invention is fully compatible with existing battery production line technology and has good prospects for mass production application. Other transparent dielectric films can be stacked on the passivation film structure to form a more complex film system structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a schematic structural diagram of a transparent laminated passivation film structure in a specific embodiment of the present invention.

[0035] FIG2 is a flow chart of a method for preparing a transparent laminated passivation film structure in a specific embodiment of the present invention.

[0036] FIG3 is a diagram of the minority carrier lifetime of the sample prepared in Example 1 of the present invention.

[0037] FIG4 is a diagram of the minority carrier lifetime of the sample prepared in Comparative Example 1 of the present invention.

[0038] FIG5 is a diagram of the minority carrier lifetime of the sample prepared in Example 7 of the present invention.

[0039] FIG6 is a diagram of the minority carrier lifetime of the sample prepared in Comparative Example 4 of the present invention.

[0040] FIG7 is a diagram of the minority carrier lifetime of the sample prepared in Example 8 of the present invention.

[0041] FIG8 is a diagram of the minority carrier lifetime of the sample prepared in Comparative Example 5 of the present invention.

[0042] Description of reference numerals: 1-silicon substrate, 2-first passivation layer, 3-second passivation layer, 4-third passivation layer. DETAILED DESCRIPTION

[0043] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be noted that the following embodiments are only intended to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter ranges described in the present invention. Reasonable variations derived therefrom are still within the scope of protection of the claims of the present invention.

[0044] It should be noted that the endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0045] A specific embodiment of the present invention provides a transparent stacked passivation film structure, a typical structure of which is shown in FIG1 , including a first passivation layer 2 , a second passivation layer 3 and a third passivation layer 4 sequentially stacked on the surface of a silicon substrate 1 .

[0046] The material of the first passivation layer 2 is a hydrogenated silicon oxide film, the main components of which are silicon, oxygen, and hydrogen. The hydrogen concentration in the first passivation layer 2 is >1×10 19 cm -3 , the typical hydrogen concentration range is 1×10 19 cm -3 ~1×10 22 cm -3 Its thickness is above 1 nm, with a typical thickness range of 1 to 20 nm, and a preferred thickness range of 1 to 2 nm. The transmittance of the first passivation layer 2 above 400 nm is greater than 97%, and the absorption coefficient k value decreases to close to 0 at wavelengths above 500 nm, showing extremely low optical absorption characteristics.

[0047] The material of the second passivation layer 3 is selected from one of hydrogenated silicon carbon nitride film, hydrogenated silicon carbon film, hydrogenated silicon nitride film, hydrogenated silicon carbon oxynitride film, hydrogenated silicon carbon oxynitride film, and hydrogenated silicon oxynitride film, and its main components are silicon, hydrogen, nitrogen and / or carbon, and may also contain oxygen. Its thickness is above 3nm, the typical thickness range is 3 to 50nm, and the preferred thickness range is 5 to 20nm. The ratio of carbon, nitrogen and other elements in the second passivation layer 3 can be adjusted, and its refractive index ranges from 1.0 to 5.0, which can be adjusted according to the composition. The hydrogen concentration in the second passivation layer 3 is >1×10 19 cm -3 , with a typical concentration range of 1×10 19 cm -3 ~1×10 22 cm -3 The second passivation layer 3 has a transmittance greater than 97% above 400 nm, and an absorption coefficient k value decreases to nearly 0 above 500 nm, showing extremely low optical absorption characteristics.

[0048] The third passivation layer 4 is a hydrogen-rich dielectric layer or a combination thereof, including but not limited to hydrogenated aluminum oxide, hydrogenated silicon nitride, hydrogenated silicon oxide or a combination thereof. The hydrogen concentration of the third passivation layer 4 is in the range of 1×10 19 cm -3 ~1×10 22 cm -3 .

[0049] The silicon substrate 1 contains hydrogen, nitrogen and / or carbon in the near-surface and bulk regions, with the concentration of the corresponding elements gradually decreasing from the surface to the bulk. In the surface region below the first passivation layer 2, the nitrogen concentration is generally higher than 1×10 19 cm -3, with a typical concentration range of 1×10 19 cm -3 ~1×10 22 cm -3 , usually more than 1×10 21 cm -3 ; Carbon concentration is generally higher than 1×10 19 cm -3 , with a typical concentration range of 1×10 19 cm -3 ~1×10 22 cm -3 , usually more than 1×10 21 cm -3 ; Hydrogen concentration is generally higher than 1×10 19 cm -3 , with a typical concentration range of 1×10 19 cm - 3 ~1×10 21 cm -3 , usually more than 1×10 20 cm -3 Introducing elements such as carbon, nitrogen, and oxygen near the surface of silicon wafers can improve the mechanical properties of silicon wafers; carbon and nitrogen atoms can effectively capture hydrogen atoms and inject them into the substrate and interface to passivate more defect states.

[0050] As shown in FIG2 , a typical method for preparing the transparent laminated passivation film structure includes the following steps:

[0051] S1. Perform standard RCA cleaning on the silicon substrate.

[0052] S2. Prepare a silicon oxide film on the surface of the silicon substrate. The preparation methods include wet chemical method, plasma assisted oxidation method, thermal oxidation method, ozone oxidation method, etc.

[0053] S3. Depositing an amorphous silicon film containing carbon and / or nitrogen elements on the silicon oxide film. The typical preparation method is PECVD in-situ deposition method, and the deposition temperature range is 100°C to 600°C.

[0054] S4. Perform high-temperature annealing treatment, typically at a temperature range of 600° C. to 1200° C., with a nitrogen atmosphere as the protective atmosphere, to crystallize the amorphous silicon and push carbon atoms and / or nitrogen atoms into the silicon substrate.

[0055] S5. Depositing one or more stacked films of aluminum oxide, silicon nitride, and silicon oxide on the polysilicon film.

[0056] S6. Perform hydrogen injection treatment. Annealing hydrogenation treatment is preferably used, with a treatment temperature of 300°C to 1000°C and a protective atmosphere containing an inert gas such as nitrogen, preferably a mixture of nitrogen and hydrogen.

[0057] The above preparation method can introduce carbon and nitrogen atoms into the silicon wafer body, and can capture more hydrogen atoms at the interface. The transparent stacked passivation film structure achieves excellent surface passivation effect and body passivation effect, and can reduce the saturation current density on the silicon wafer surface to 0.2fA / cm 2 , which can increase the life of n-type silicon wafers to more than 15ms.

[0058] The transparent stacked passivation film structure is suitable for silicon-based semiconductor devices, and the preparation method is fully compatible with existing battery production line technology. Other transparent dielectric films can be superimposed on the passivation film structure to form a more complex film system structure to improve device performance.

[0059] The technical solutions and effects of the present invention are described below through specific embodiments.

[0060] Example 1

[0061] Prepare n-type silicon wafers, flat, 110 μm thick, with a resistivity of 1 to 7 Ω·cm. After standard RCA cleaning, the silicon wafers are placed in a PECVD chamber and N2O plasma is used to prepare SiO x film, and then deposited nitrogen-rich amorphous silicon film (nitrogen content of 15at%); annealed at 900℃ for 30min in a tube furnace; ALD deposited AlO x , annealed at 450℃ in a tube furnace for 30min; then transferred to PECVD to deposit SiN x Finally, annealing was carried out at 400℃ for 60min in a mixed gas atmosphere of nitrogen and hydrogen in a tube furnace. Six samples were prepared and Sinton test was carried out. The single-side saturation current density J 0,s The test results range is 0.3~0.6fA / cm 2 A sample was selected to test the lifetime. The minority carrier lifetime spectrum is shown in Figure 3, and the test result is ~15ms.

[0062] Example 2

[0063] Prepare n-type silicon wafers, flat, 110μm thick, with a resistivity of 1-7Ω·cm. After standard RCA cleaning, the silicon wafers are placed in a PECVD chamber and N2O plasma is used to prepare SiO x film, and then deposited carbon-rich amorphous silicon film (carbon content of 15at%); annealed at 900℃ for 30min in a tube furnace; ALD deposited AlO x , annealed at 450℃ in a tube furnace for 30min; then transferred to PECVD to deposit SiN xFinally, annealing was carried out at 400℃ for 60min in a mixed gas atmosphere of nitrogen and hydrogen in a tube furnace. Six samples were prepared and Sinton test was carried out. The single-side saturation current density J 0,s The test results range is 0.5~0.9fA / cm 2 .

[0064] Example 3

[0065] Prepare n-type silicon wafers, flat, 110μm thick, with a resistivity of 1-7Ω·cm. After standard RCA cleaning, the silicon wafers are placed in a PECVD chamber and N2O plasma is used to prepare SiO x film, and then deposit nitrogen-rich and carbon-rich amorphous silicon film (nitrogen content of 5at%, carbon content of 10at%); annealing at 900℃ for 30min in a tube furnace; ALD deposition of AlO x , annealed at 450℃ in a tube furnace for 30min; then transferred to PECVD to deposit SiN x Finally, annealing was carried out at 400℃ for 60min in a mixed gas atmosphere of nitrogen and hydrogen in a tube furnace. Six samples were prepared and Sinton test was carried out. The single-side saturation current density J 0,s The test results range is 0.2~0.5fA / cm 2 .

[0066] Example 4

[0067] Prepare n-type silicon wafers, flat, 110μm thick, with a resistivity of 1-7Ω·cm. After standard RCA cleaning, the silicon wafers are placed in a PECVD chamber and N2O plasma is used to prepare SiO x A thin film was deposited, followed by deposition of nitrogen-rich and oxygen-rich amorphous silicon thin films (nitrogen content of 15at%, oxygen content of 5at%); annealing at 900°C for 30min in a tube furnace; and ALD deposition of AlO x , annealed at 450℃ in a tube furnace for 30min; then transferred to PECVD to deposit SiN x Finally, annealing was carried out at 400℃ for 60min in a mixed gas atmosphere of nitrogen and hydrogen in a tube furnace. Six samples were prepared and Sinton test was carried out. The single-side saturation current density J 0,s The test results range is 0.2~0.6fA / cm 2 .

[0068] Example 5

[0069] Prepare n-type silicon wafers, flat, 110μm thick, with a resistivity of 1-7Ω·cm. After standard RCA cleaning, the silicon wafers are placed in a PECVD chamber and N2O plasma is used to prepare SiO xfilm, and then deposited carbon and oxygen-rich amorphous silicon film (carbon content of 15at%, oxygen content of 5at%); annealed at 900℃ for 30min in a tube furnace; ALD deposited AlO x , annealed at 450℃ in a tube furnace for 30min; then transferred to PECVD to deposit SiN x Finally, annealing was carried out at 400℃ for 60min in a mixed gas atmosphere of nitrogen and hydrogen in a tube furnace. Six samples were prepared and Sinton test was carried out. The single-side saturation current density J 0,s The test results range is 0.4~0.8fA / cm 2 .

[0070] Example 6

[0071] Prepare n-type silicon wafers, flat, 110μm thick, with a resistivity of 1-7Ω·cm. After standard RCA cleaning, the silicon wafers are placed in a PECVD chamber and N2O plasma is used to prepare SiO x The film was then deposited with nitrogen-rich, carbon-rich, and oxygen-rich amorphous silicon films (nitrogen content of 5at%, carbon content of 5at%, and oxygen content of 5at%); annealed at 900°C for 30 minutes in a tube furnace; and ALD deposited AlO x , annealed at 450℃ in a tube furnace for 30min; then transferred to PECVD to deposit SiN x Finally, annealing was carried out at 400℃ for 60min in a mixed gas atmosphere of nitrogen and hydrogen in a tube furnace. Six samples were prepared and Sinton test was carried out. The single-side saturation current density J 0,s The test results range is 0.2~0.5fA / cm 2 .

[0072] Example 7

[0073] Prepare n-type silicon wafers with a textured surface, thickness of 200 μm, and resistivity of 1 to 7 Ω·cm. After standard RCA cleaning, the silicon wafers are placed in a PECVD chamber and SiO is prepared by N2O plasma. x film, and then deposited nitrogen-rich amorphous silicon film (nitrogen content of 15at%); annealed at 900℃ for 30min in a tube furnace; ALD deposited AlO x , annealed at 450℃ in a tube furnace for 30min; then transferred to PECVD to deposit SiN x Finally, annealing was carried out at 400℃ for 60min in a mixed gas atmosphere of nitrogen and hydrogen in a tube furnace. Six samples were prepared and Sinton test was carried out. The single-side saturation current density J 0,s The test results range is 0.8~1.5fA / cm 2 A sample was selected to test the lifetime. The minority carrier lifetime spectrum is shown in Figure 5, and the test result is ~10ms.

[0074] Example 8

[0075] Prepare double-sided phosphorus-expanded p-type silicon wafers with a textured surface, a thickness of 170μm, and a resistivity of 1-15Ω·cm. After standard RCA cleaning, the silicon wafers are placed in a PECVD chamber and N2O plasma is used to prepare SiO x film, and then deposited nitrogen-rich amorphous silicon film (nitrogen content of 15at%); annealed at 900℃ for 30min in a tube furnace; ALD deposited AlO x , annealed at 450℃ in a tube furnace for 30min; then transferred to PECVD to deposit SiN x Finally, annealing was carried out at 400℃ for 60min in a mixed gas atmosphere of nitrogen and hydrogen in a tube furnace. Six samples were prepared and Sinton test was carried out. The single-side saturation current density J 0,s The test results range is 15~20fA / cm 2 A sample was selected to test the lifetime. The minority carrier lifetime spectrum is shown in Figure 7, and the test result is ~1.8ms.

[0076] Comparative Example 1

[0077] Prepare n-type silicon wafers with a thickness of 110 μm and a resistivity of 1 to 7 Ω·cm. After standard RCA cleaning, place the wafers in the ALD chamber to deposit AlO x , then transferred to a tube furnace and annealed at 450℃ for 30min under nitrogen atmosphere. 6 samples were prepared and Sinton test was performed. The single-side saturation current density J 0,s The test results range is 3.0~5.0fA / cm 2 A sample was selected to test the lifetime. The minority carrier lifetime spectrum is shown in Figure 4, and the test result is ~5.6ms.

[0078] Comparative Example 2

[0079] Prepare n-type silicon wafers with a thickness of 110 μm and a resistivity of 1 to 7 Ω·cm. After standard RCA cleaning, place the wafers in the ALD chamber to deposit AlO x , then transferred to a tube furnace for annealing at 450 ° C for 30 min under a nitrogen atmosphere; transferred to PECVD to deposit SiN x Finally, the samples were transferred to a tube furnace and annealed at 400℃ for 60min in a nitrogen / hydrogen mixed gas. Six samples were prepared and Sinton test was performed. The single-side saturation current density J 0,s The test results range is 2.0~4.0fA / cm 2 .

[0080] Comparative Example 3

[0081] Prepare n-type silicon wafers with a thickness of 110 μm and a resistivity of 1 to 7 Ω·cm. After standard RCA cleaning, the silicon wafers are placed in a tube furnace and prepared in an oxygen atmosphere. x , and then transferred to the PECVD chamber to deposit SiN x Finally, annealing was carried out at 400℃ for 60min in a tube furnace under a mixture of nitrogen and hydrogen. Six samples were prepared and Sinton test was carried out. The single-side saturation current density J 0,s The test results range is 8.0~12.0fA / cm 2 .

[0082] Comparative Example 4

[0083] Prepare n-type silicon wafers with a textured surface, thickness of 200 μm, and resistivity of 1 to 7 Ω·cm. After standard RCA cleaning, the silicon wafers are placed in the ALD chamber to deposit AlO x , then transferred to a tube furnace and annealed at 450℃ for 30min under nitrogen atmosphere. 6 samples were prepared and Sinton test was performed. The single-side saturation current density J 0,s The test results range is 5~10fA / cm 2 A sample was selected to test the lifetime. The minority carrier lifetime spectrum is shown in Figure 6, and the test result is ~5ms.

[0084] Comparative Example 5

[0085] Prepare double-sided phosphorus-expanded p-type silicon wafers with a textured surface, a thickness of 170 μm, and a resistivity of 1-15 Ω·cm. After standard RCA cleaning, the silicon wafers were placed in a tube furnace and prepared in an oxygen atmosphere. x , and then transferred to the PECVD chamber to deposit SiN x Finally, annealing was carried out at 400℃ for 60min in a tube furnace under a mixture of nitrogen and hydrogen. Six samples were prepared and Sinton test was carried out. The single-side saturation current density J 0,s The test results range from 25 to 35 fA / cm 2 A sample was selected to test the lifetime. The minority carrier lifetime spectrum is shown in Figure 8, and the test result is ~0.8ms.

[0086] The single-side saturation current density J of the above examples 1-8 and comparative examples 1-5 is 0,s The test results are shown in Table 1 below. The results show that the transparent laminated passivation film structure of the present invention has an excellent passivation effect and can significantly reduce the saturation current density.

[0087] Table 1 Comparison of single-sided saturation current density of passivation structures of Examples 1-6 and Comparative Examples 1-3

[0088] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A transparent laminated passivation film structure, characterized in that, It includes a first passivation layer, a second passivation layer, and a third passivation layer that are sequentially stacked on the surface of a silicon substrate. The material of the first passivation layer is a silicon oxynitride film, the material of the second passivation layer is selected from one of a silicon carbonitride film, a silicon carbide film, a silicon nitride film, a silicon carbonitride oxide film, a silicon carbon oxide film, and a silicon nitride oxide film, and the material of the third passivation layer is selected from one or more laminated films of an aluminum oxide film, a silicon nitride film, and a silicon oxynitride film.

2. The transparent stacked passivation film structure according to claim 1, wherein The silicon substrate contains hydrogen, carbon, and / or nitrogen elements, and the concentrations of these elements gradually decrease from the surface to the interior.

3. The transparent stacked passivation film structure according to claim 2, wherein The hydrogen concentration on the surface of the silicon substrate is 1×10 19 cm -3 ~1×10 21 cm -3 .

4. The transparent laminated passivation film structure according to claim 3, wherein, The nitrogen concentration on the surface of the substrate is 1×10 19 cm -3 ~1×10 22 cm -3 , and / or the carbon concentration is 1×10 19 cm -3 ~1×10 22 cm - 3 。 5. The transparent laminated passivation film structure according to any one of claims 1-4, characterized in that, The hydrogen concentration of the first passivation layer is 1×10 19 cm -3 ~1×10 22 cm -3 , the hydrogen concentration of the second passivation layer is 1×10 19 cm -3 ~1×10 22 cm -3 , and the hydrogen concentration of the third passivation layer is 1×10 19 cm -3 ~1×10 22 cm -3 .

6. The transparent stacked passivation film structure according to claim 5, characterized in that, The refractive index of the second passivation layer is 1.0 to 5.

0.

7. The transparent stacked passivation film structure according to claim 5, wherein, The transmittance of the first passivation layer above 400 nm is greater than 97%, and the transmittance of the second passivation layer above 400 nm is greater than 97%.

8. The transparent stacked passivation film structure according to claim 5, wherein, The thickness of the first passivation layer is 1 to 20 nm, and the thickness of the second passivation layer is greater than or equal to 2 nm.

9. A method for preparing a transparent laminated passivation film structure according to any one of claims 1-8, characterized in that, It includes the following steps: S1. Clean the silicon substrate. S2. Prepare a silicon oxide film on the surface of the silicon substrate. S3. Deposit an amorphous silicon film containing carbon and / or nitrogen elements on the silicon oxide film. S4. Perform a high-temperature annealing treatment at a treatment temperature of 600°C to 1200°C to convert the amorphous silicon film into a polycrystalline silicon film. S5. Deposit one or more laminated films of aluminum oxide, silicon nitride, and silicon oxide on the polycrystalline silicon film. S6. Perform a hydrogen injection treatment.

10. The preparation method of the transparent stacked passivation film structure according to claim 9, characterized in that, In step S6, an annealing hydrogenation treatment is used, and the treatment temperature is 300°C to 1000°C.

11. The method for preparing the transparent stacked passivation film structure according to claim 9, wherein, In step S3, an amorphous silicon film containing carbon and / or nitrogen elements is in-situ deposited by PECVD.

12. A silicon-based semiconductor device, characterized in that, It includes the transparent laminated passivation film structure according to any one of claims 1-8.

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