Method for forming aluminum oxide passivation film on surface of semiconductor substrate material, PERC battery and preparation method of PERC battery

Abstract

The invention provides a method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material, a PERC battery and a preparation method of the PERC battery. The method comprises the following steps: carrying out at least two times of atomic layer deposition on the surface of one side of a semiconductor substrate material to obtain an aluminum oxide passivation film; the atomic layer deposition process is carried out in a reaction chamber of the atomic layer deposition equipment, and during each atomic layer deposition, an aluminum source is firstly introduced into the reaction chamber and then ozone is introduced into the reaction chamber. Compared with the mode that ozone is firstly introduced into the reaction chamber, the mode that the aluminum source is firstly introduced and then the ozone is introduced is adopted, silicon oxide can be inhibited from being generated firstly, the passivation effect can be improved by forming the aluminum oxide passivation film on the surface of one side of the semiconductor substrate material firstly, and therefore the photoelectric conversion efficiency of the PERC battery is improved; and meanwhile, the deposition time of aluminum oxide can be shortened, EL black spots generated by an aluminum oxide passivation film due to introduction of impurities are inhibited, the product yield can be increased, and large-batch production is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material, a PERC cell and a preparation method thereof. Background Art

[0002] Compared with traditional cells, PERC cells (Passivated Emitter and Rear Cell) reduce the recombination of minority carriers and improve the conversion efficiency of cells by adding a back passivation layer on the basis of the conventional back electric field structure. They are currently the most widely used solar cells. The current manufacturing process of PERC cells mainly includes texturing, diffusion, SE (selective emitter), etching, annealing, back passivation, front and back PECVD (plasma enhanced chemical vapor deposition), screen printing, sintering, and testing. Among them, the back passivation process mainly includes plasma enhanced chemical vapor deposition (PECVD) and atomic layer deposition (ALD).

[0003] The existing document (publication number CN114038945A) discloses a method for preparing a new PERC cell by a single-sided ALD method, which includes the following steps: before depositing a single-sided aluminum oxide film, a dense silicon oxide layer is generated by ozone oxidation (oxidation time is 1 to 10 minutes), and then single-sided aluminum oxide deposition, silicon nitride deposition, and then metal back electric field printing are performed in sequence to form a new PERC cell. It is difficult to generate a silicon oxide layer with uniform and controllable thickness by pre-introducing ozone oxidation and reacting with silicon wafers, and silicon oxide will be generated locally, which will increase the interface defect density and weaken the passivation effect of the aluminum oxide passivation film, thereby reducing the photoelectric conversion efficiency of the prepared PERC cell; moreover, pre-introducing ozone will prolong the aluminum oxide deposition time, which is not conducive to mass production.

[0004] In addition, the back-side passivation process has high requirements on the environment inside the equipment cavity. The existing back-side passivation process also has problems such as long processing time and the introduction of more impurities, which leads to more "black spots" in the electroluminescence (EL) test image, which limits the improvement of PERC cell yield.

[0005] Therefore, in order to improve the above problems, it is urgent to develop a method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material, which is of great significance for improving the performance of PERC cells. Summary of the invention

[0006] The main purpose of the present invention is to provide a method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material, a PERC cell and a preparation method thereof, so as to solve the problems of poor passivation effect and low product yield of the aluminum oxide passivation film in the prior art.

[0007] In order to achieve the above-mentioned purpose, the present invention provides, on one hand, a method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material, the method comprising: performing at least two atomic layer depositions on the surface of one side of the semiconductor substrate material to obtain an aluminum oxide passivation film; the atomic layer deposition process is carried out in a reaction chamber of an atomic layer deposition device, wherein, during each atomic layer deposition, an aluminum source is first introduced into the reaction chamber and then ozone is introduced.

[0008] Furthermore, each atomic layer deposition process includes the following steps: step S21, introducing the aluminum source into the reaction chamber through the aluminum source supply pipe, and the introduction time is 3000-4000ms; step S22, after the aluminum source is introduced, ozone is introduced into the reaction chamber through the ozone supply pipe, and the introduction time is 1500-2000ms; step S23, using inert gas to perform a first purge on the aluminum source supply pipe and the ozone supply pipe respectively; step S24, performing a first vacuum treatment on the reaction chamber; step S25, introducing ozone into the reaction chamber, and setting the introduction time to 5000-6000ms; step S26, performing a second vacuum treatment on the reaction chamber; step S27, using inert gas to perform a second purge on the aluminum source supply pipe and the ozone supply pipe respectively; step S28, performing a third vacuum treatment on the reaction chamber; preferably, the aluminum source is trimethylaluminum; preferably, the semiconductor substrate material is p-type silicon substrate material.

[0009] Furthermore, the volume of the reaction chamber is 72-73m 3 In step S21, the aluminum source is introduced at a rate of 3000 to 4000 sccm; and / or, in step S22, the ozone introduction rate is 2000 to 3000 sccm; and / or, in step S23, the inert gas introduction rate during the first purge is independently selected from 8000 to 10000 sccm; and / or, in step S24, the first vacuum treatment time is 1500 to 2000 ms, so that the vacuum degree of the reaction chamber is 1 to 2 Pa; and / or, in step S25 , the ozone introduction rate is 5000-7000 sccm; and / or, in step S26, the second vacuum treatment time is 500-1000 ms, so that the vacuum degree of the reaction chamber is 1-2 Pa; and / or, in step S27, the inert gas introduction rate during the second purge is independently selected from 8000-10000 sccm; and / or, in step S28, the third vacuum treatment time is 1500-2000 ms, so that the vacuum degree of the reaction chamber is 1-2 Pa.

[0010] Furthermore, the method includes: performing 30 to 34 atomic layer depositions on one side surface of the semiconductor substrate material to obtain an aluminum oxide passivation film.

[0011] Furthermore, before the atomic layer deposition process is performed, the method further includes a process of preheating the semiconductor substrate material; preferably, the temperature of the atomic layer deposition process is lower than the temperature of the preheating process, and the temperature difference between the two is ≤5°C.

[0012] Furthermore, the temperature of the preheating process is 180-200°C, the time is 240-270s, and the heating rate is 6-10°C / min.

[0013] Further, when the temperature of the preheating process is 180-190°C and the temperature of the atomic layer deposition process is 180-190°C, in step S21, the introduction rate of the aluminum source is 3000-3300sccm, and the introduction time is 3000-3300ms, in step S22, the introduction rate of ozone is 2000-2300sccm, and the introduction time is 1500-1700ms, and in step S25, the introduction rate of ozone is 5000-6000sccm, and the introduction time is 5000-5300ms; when the temperature of the preheating process is 191-195°C and the temperature of the atomic layer deposition process is 191-195°C, in step S21, the introduction rate of the aluminum source is 3300-3700sccm, and the introduction time is 3300-3700ms, and step S22 is 2000-2300sccm. In step S22, the ozone introduction rate is 2300-2700sccm, and the introduction time is 1700-1800ms. In step S25, the ozone introduction rate is 6000-6500sccm, and the introduction time is 5300-5500ms. When the temperature of the preheating process is 196-200°C and the temperature of the atomic layer deposition process is 196-200°C, in step S21, the aluminum source introduction rate is 3700-4000sccm, and the introduction time is 3700-4000ms. In step S22, the ozone introduction rate is 2700-3000sccm, and the introduction time is 1800-2000ms. In step S25, the ozone introduction rate is 6500-7000sccm, and the introduction time is 5500-6000ms.

[0014] In order to achieve the above-mentioned object, another aspect of the present invention further provides a method for preparing a PERC cell, which comprises the method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material as provided in the present application.

[0015] Another aspect of the present invention provides a PERC cell, which is manufactured by the above-mentioned PERC cell manufacturing method provided in the present application.

[0016] Furthermore, the PERC cell includes an aluminum oxide passivation film, and the thickness of the aluminum oxide passivation film is 2 to 5 nm.

[0017] By applying the technical solution of the present invention, during the atomic layer deposition process, an aluminum source reacts chemically with ozone to obtain aluminum oxide, water and carbon dioxide. The generated aluminum oxide undergoes chemical adsorption or reaction on the semiconductor substrate material, thereby growing layer by layer to form a single atomic layer. Performing atomic layer deposition at least twice can obtain an aluminum oxide passivation film.

[0018] Compared to first introducing ozone into the reaction chamber, the present application adopts a method of first introducing an aluminum source and then introducing ozone, which can inhibit the generation of silicon oxide on the surface of the semiconductor substrate. The method provided by the present application is used to first prepare an aluminum oxide passivation film on one side of the semiconductor substrate material, which can improve the passivation effect of the product, thereby improving the photoelectric conversion efficiency of the PERC cell; at the same time, it can also shorten the deposition time of aluminum oxide, inhibit the introduction of impurities, reduce the defect state density, and reduce the proportion of EL black spots generated by the aluminum oxide passivation film, thereby improving the product yield and facilitating mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0020] Figure 1 The schematic diagram of the structure of the PERC cell prepared in Example 1 of the present application is shown;

[0021] Figure 2 The schematic diagram of the structure of the conventional battery prepared in Comparative Example 1 of the present application is shown.

[0022] The above drawings include the following reference numerals:

[0023] 1. Front SiOx layer; 2. Front SiON layer; 3. Front SiNx layer; 4. Silicon substrate layer; 5. Back aluminum oxide passivation layer; 6. Back SiNx layer; 7. Back silicon oxide passivation layer. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0025] As described in the background technology, the existing aluminum oxide passivation film has the problems of poor passivation effect and low product yield. In order to solve the above technical problems, the present application provides a method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material, the method comprising: performing at least two atomic layer depositions on one side surface of the semiconductor substrate material to obtain an aluminum oxide passivation film; the atomic layer deposition process is performed in a reaction chamber of an atomic layer deposition device, wherein each time an atomic layer deposition is performed, an aluminum source is first introduced into the reaction chamber and then ozone is introduced.

[0026] During the atomic layer deposition process, the aluminum source reacts chemically with ozone to produce aluminum oxide, water and carbon dioxide. The generated aluminum oxide undergoes chemical adsorption or reaction on the semiconductor substrate material, thereby growing layer by layer to form a single atomic layer. Performing at least two atomic layer depositions can obtain an aluminum oxide passivation film.

[0027] When the aluminum source is trimethylaluminum, the overall reaction equation in the process is shown in formula (I):

[0028] Al(CH 3 ) 3 +O 3 →Al 2 O 3 +H 2 O+CO 2 (I).

[0029] Compared to first introducing ozone into the reaction chamber, the present application adopts a method of first introducing an aluminum source and then introducing ozone, which can inhibit the generation of silicon oxide on the surface of the semiconductor substrate. The method provided by the present application is used to first prepare an aluminum oxide passivation film on one side of the semiconductor substrate material, which can improve the passivation effect of the product, thereby improving the photoelectric conversion efficiency of the PERC cell; at the same time, it can also shorten the deposition time of aluminum oxide, inhibit the introduction of impurities, reduce the defect state density, and reduce the proportion of EL black spots generated by the aluminum oxide passivation film, thereby improving the product yield and facilitating mass production.

[0030] In a preferred embodiment, each atomic layer deposition process includes the following steps: step S21, introducing the aluminum source into the reaction chamber through the aluminum source supply pipe, and the introduction time is 3000-4000ms; step S22, after the aluminum source is introduced, ozone is introduced into the reaction chamber through the ozone supply pipe, and the introduction time is 1500-2000ms; step S23, using inert gas to perform the first purge on the aluminum source supply pipe and the ozone supply pipe respectively; step S24, performing the first vacuum treatment on the reaction chamber; step S25, introducing ozone into the reaction chamber, and setting the introduction time to 5000-6000ms; step S26, performing the second vacuum treatment on the reaction chamber; step S27, using inert gas to perform the second purge on the aluminum source supply pipe and the ozone supply pipe respectively; step S28, performing the third vacuum treatment on the reaction chamber.

[0031] Compared with the existing ALD deposition process, the present application adopts the above steps S21 to S28 to facilitate precise control of the reaction process, which is beneficial to improving the thickness uniformity and density of the aluminum oxide passivation film. At the same time, limiting the introduction time of the aluminum source and ozone and the time of the three inert gas purges within the above range is beneficial to shortening the aluminum oxide deposition time, reducing the amount of impurities introduced during the reaction process, and reducing the defect state density, thereby helping to reduce the EL black spots generated by the aluminum oxide passivation film. When it is used as a back passivation layer in a PERC cell, it is beneficial to suppress carrier recombination, thereby helping to improve the photoelectric conversion efficiency of the PERC cell.

[0032] It should be noted that the units sccm and m in this application are 3 The conversion relationship of / s is shown in formula (II):

[0033] 1sccm=1.667×10 -8 m 3 / s(II).

[0034] In a preferred embodiment, the aluminum source is trimethylaluminum. Compared with other types, using trimethylaluminum as an aluminum source is beneficial to improving the safety of the reaction and reducing the preparation cost.

[0035] In a preferred embodiment, the semiconductor substrate material is a p-type silicon substrate material, which is convenient for application in PERC cells.

[0036] In a preferred embodiment, the volume of the reaction chamber is 72-73 m 3 In step S21, the aluminum source is introduced at a rate of 3000 to 4000 sccm. The aluminum source introduction rate includes but is not limited to the above range. Limiting it within the above range is conducive to better controlling the thickness of the aluminum oxide passivation film and the uniformity of the coating, and is conducive to reducing the defect state density, thereby improving the passivation effect of the aluminum oxide passivation film.

[0037] In a preferred embodiment, the volume of the reaction chamber is 72-73 m 3 In step S22, the ozone introduction rate is 2000-3000 sccm. The ozone introduction rate includes but is not limited to the above range. Limiting it within the above range is conducive to better controlling the reaction rate and coating uniformity, and is conducive to reducing its defect state density, thereby helping to improve the passivation effect of the aluminum oxide passivation film.

[0038] In a preferred embodiment, the volume of the reaction chamber is 72-73 m 3In step S23, the inert gas introduction rate during the first purge independently includes but is not limited to 8000-10000 sccm. The purge rate of the inert gas (first time) includes but is not limited to the above range, and limiting it within the above range is conducive to removing impurities remaining on the silicon wafer, thereby inhibiting the influence of impurities on the aluminum oxide passivation film.

[0039] In a preferred embodiment, the volume of the reaction chamber is 72-73 m 3 In step S24, the first vacuum treatment time is 1500-2000 ms, so that the vacuum degree of the reaction chamber is 1-2 Pa. The first vacuum treatment time includes but is not limited to the above range, and limiting it within the above range is conducive to removing residual water and carbon dioxide in the reaction chamber, improving the passivation effect of the aluminum oxide passivation film, and reducing its defect state density.

[0040] In a preferred embodiment, the volume of the reaction chamber is 72-73 m 3 In step S25, the ozone introduction rate is 5000-7000 sccm. The ozone introduction rate includes but is not limited to the above range. Limiting it within the above range is conducive to better controlling the reaction rate and coating uniformity, reducing its defect state density, and improving the passivation effect of the aluminum oxide passivation film.

[0041] In a preferred embodiment, the volume of the reaction chamber is 72-73 m 3 In step S26, the second vacuum treatment time is 500-1000 ms, so that the vacuum degree of the reaction chamber is 1-2 Pa. The second vacuum treatment time includes but is not limited to the above range, and limiting it within the above range is conducive to removing residual water and carbon dioxide in the reaction chamber, and is conducive to reducing its defect state density, thereby helping to improve the passivation effect of the aluminum oxide passivation film.

[0042] In a preferred embodiment, the volume of the reaction chamber is 72-73 m 3 In step S27, the inert gas introduction rate during the second purge independently includes but is not limited to 8000-10000 sccm. The purge rate of the inert gas (second time) includes but is not limited to the above range, and limiting it within the above range is conducive to removing impurities remaining on the surface of the semiconductor substrate material and reducing impurities in the pipeline.

[0043] In a preferred embodiment, the volume of the reaction chamber is 72-73 m 3In step S28, the time of the third vacuum treatment is 1500-2000 ms, so that the vacuum degree of the reaction chamber is 1-2 Pa. The time of the third vacuum treatment includes but is not limited to the above range, and limiting it within the above range is conducive to removing residual water and carbon dioxide in the reaction chamber, and is conducive to reducing its defect state density, thereby facilitating improving the passivation effect of the aluminum oxide passivation film.

[0044] In a preferred embodiment, the method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material comprises: performing 30 to 34 atomic layer depositions on one side of the semiconductor substrate material to obtain an aluminum oxide passivation film. Compared with other ranges, limiting the number of atomic layer depositions to the above range is conducive to controlling the thickness of the aluminum oxide passivation film within an appropriate range, thereby facilitating the improvement of the photoelectric conversion efficiency of the PERC cell; and also facilitating the improvement of the production efficiency of the PERC cell.

[0045] In a preferred embodiment, before the atomic layer deposition process, the method provided by the present application further includes a process of preheating the semiconductor substrate material. Preheating the semiconductor substrate material facilitates heating its temperature to the temperature required for the atomic layer deposition process, which is beneficial to improving the uniformity of the aluminum oxide passivation film subsequently obtained, and is also beneficial to shortening the time required for atomic layer deposition, thereby facilitating improving the production efficiency of PERC cells.

[0046] In order to further improve the uniformity of the subsequently prepared aluminum oxide passivation film and further improve the production efficiency of the PERC battery, preferably, the temperature of the atomic layer deposition process is lower than the temperature of the preheating process, and the temperature difference between the two is ≤5°C.

[0047] In a preferred embodiment, the temperature of the preheating process is 180-200°C, the time is 240-270s, and the heating rate is 6-10°C / min. The temperature and time of the preheating process include but are not limited to the above ranges. Limiting them within the above ranges is conducive to further improving the uniformity of the subsequently prepared aluminum oxide passivation film, and is also conducive to further shortening the time required for atomic layer deposition, thereby further improving the production efficiency of PERC cells.

[0048] For a specific preheating temperature and the temperature of the atomic layer deposition process, the atomic layer deposition process parameters are preferably selected accordingly. In a preferred embodiment, when the temperature of the preheating process is 180-190°C and the temperature of the atomic layer deposition process is 180-190°C, in step S21, the aluminum source is introduced at a rate of 3000-3300 sccm and the introduction time is 3000-3300 ms; in step S22, the ozone is introduced at a rate of 2000-2300 sccm and the introduction time is 1500-1700 ms; in step S25, the ozone is introduced at a rate of 5000-6000 sccm and the introduction time is 5000-5300 ms.

[0049] For a specific preheating temperature and the temperature of the atomic layer deposition process, the atomic layer deposition process parameters are preferably selected accordingly. In a preferred embodiment, when the temperature of the preheating process is 191-195°C and the temperature of the atomic layer deposition process is 191-195°C, in step S21, the aluminum source is introduced at a rate of 3300-3700 sccm and the introduction time is 3300-3700 ms; in step S22, the ozone is introduced at a rate of 2300-2700 sccm and the introduction time is 1700-1800 ms; in step S25, the ozone is introduced at a rate of 6000-6500 sccm and the introduction time is 5300-5500 ms.

[0050] For a specific preheating temperature and the temperature of the atomic layer deposition process, the atomic layer deposition process parameters are preferably selected accordingly. In a preferred embodiment, when the temperature of the preheating process is 196-200°C and the temperature of the atomic layer deposition process is 196-200°C, in step S21, the aluminum source is introduced at a rate of 3700-4000sccm and the introduction time is 3700-4000ms; in step S22, the ozone is introduced at a rate of 2700-3000sccm and the introduction time is 1800-2000ms; in step S25, the ozone is introduced at a rate of 6500-7000sccm and the introduction time is 5500-6000ms.

[0051] The second aspect of the present application also provides a method for preparing a PERC cell, which includes the method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material provided in the present application. The aluminum oxide passivation film prepared by the above method of the present application has the advantages of good passivation effect, few defects and high yield. The application of the above aluminum oxide passivation film provided by the present application in a PERC cell can significantly improve the photoelectric conversion efficiency of the PERC cell.

[0052] The third aspect of the present application also provides a PERC cell, which is prepared by the preparation method of the PERC cell provided by the present application. The aluminum oxide passivation film prepared by the above method of the present application has the advantages of good passivation effect, few defects and high yield. The above aluminum oxide passivation film provided by the present application is applied to the PERC cell, which can significantly improve the photoelectric conversion efficiency of the PERC cell.

[0053] In a preferred embodiment, the thickness of the aluminum oxide passivation film is 2 to 5 nm. The thickness of the aluminum oxide passivation film includes but is not limited to the above range. Limiting it within the above range is conducive to improving the passivation effect of the aluminum oxide passivation film, and when it is used as a back passivation layer in a PERC cell, it is conducive to improving the passivation effect, thereby helping to improve the photoelectric conversion efficiency of the PERC cell.

[0054] In a preferred embodiment, Figure 1 As shown, the PERC cell includes a front SiOx layer 1, a front SiON layer 2, a front SiNx layer 3, a silicon substrate layer 4, a back aluminum oxide passivation layer 5 and a back SiNx layer 6 which are stacked in sequence.

[0055] In a preferred embodiment, the thickness of the front SiOx layer 1 is 10-15 nm, the thickness of the front SiON layer 2 is 25-30 nm, the thickness of the front SiNx layer 3 is 30-40 nm, and the total thickness of the front is 65-80 nm; the thickness of the silicon substrate layer 4 is 150-170 μm, the thickness of the back aluminum oxide passivation layer 5 is 2-5 nm, and the thickness of the back SiNx layer 5 is 75-95 nm.

[0056] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0057] Example 1

[0058] A method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material, comprising:

[0059] (1) Prepare a silicon wafer with a size of 182×182 mm and a thickness of 130 μm, and insert the silicon wafer into the aluminum boat using a "positive-to-positive" double insertion method;

[0060] (2) The aluminum boat is placed in the reaction chamber of the ALD3.0 atomic layer deposition equipment of Songyu Technology, the volume of which is 72.6m 3 The vacuum degree inside is 1.1 Pa, and the temperature is raised to 200°C at a heating rate of 8°C / min and maintained for 60s to obtain a preheated silicon wafer;

[0061] (3) Atomic layer deposition was performed 32 times, and each atomic layer deposition process included the following steps:

[0062] (3.1) Introduce trimethylaluminum (TMA) into the reaction chamber through the trimethylaluminum supply pipeline at a flow rate of 3500 sccm, and set the introduction time to 4000 ms.

[0063] (3.2) After the introduction of TMA is completed, introduce ozone into the reaction chamber through the ozone supply pipeline at a flow rate of 3000 sccm, and set the introduction time to 2000 ms.

[0064] (3.3) First, purge the TMA supply pipeline and the ozone supply pipeline with nitrogen with a purity of 99.99%. When purging the TMA supply pipeline, the nitrogen flow rate is 10000 sccm, and when purging the ozone supply pipeline, the nitrogen flow rate is 10000 sccm. The purging time is 8000 ms for both.

[0065] (3.4) After the first purge is completed, evacuate the reaction chamber for 2000 ms to make the vacuum degree of the reaction chamber 1.2 Pa.

[0066] (3.5) Then introduce ozone into the reaction chamber at a flow rate of 5500 sccm, and set the introduction time to 5500 ms.

[0067] (3.6) After the introduction of ozone is completed, evacuate the reaction chamber for 1000 ms to make the vacuum degree of the reaction chamber 1.1 Pa.

[0068] (3.7) Then, respectively, perform a second purge on the TMA supply pipeline and the ozone supply pipeline with nitrogen with a purity of 99.99%. When purging the TMA supply pipeline, the nitrogen flow rate is 10000 sccm, and when purging the ozone supply pipeline, the nitrogen flow rate is 10000 sccm. The purging time is 8000 ms for both.

[0069] (3.8) After the second purge is completed, evacuate the reaction chamber for 1500 ms to make the vacuum degree of the reaction chamber 1.2 Pa.

[0070] In Example 1, an alumina passivation film with a thickness of 3.35 nm is finally obtained.

[0071] Make the alumina passivation film prepared in Example 1 into a PERC cell. The preparation method of this PERC cell includes the following steps:

[0072] Perform texturing, diffusion, SE (selective emitter), etching, annealing, back passivation, front coating PECVD (plasma enhanced chemical vapor deposition), back coating PECVD (plasma enhanced chemical vapor deposition), back film laser grooving, screen printing, sintering, light injection or electrical injection on the silicon wafer in sequence to obtain a PERC cell.

[0073] like Figure 1 As shown, the PERC cell includes a front SiOx layer 1, a front SiON layer 2, a front SiNx layer 3, a silicon substrate layer 4, a back aluminum oxide passivation layer 5 and a back SiNx layer 6 which are stacked in sequence, wherein the thickness of the front SiOx layer 1 is 12 nm, the thickness of the front SiON layer 2 is 16 nm, the thickness of the front SiNx layer 3 is 50 nm, and the total thickness of the front side is 78 nm; the thickness of the silicon substrate layer 4 is 150 μm, the thickness of the back aluminum oxide passivation layer 5 is 3.35 nm, and the thickness of the back SiNx layer 6 is 85 nm.

[0074] Example 2

[0075] The difference from Example 1 is that in step (3.1), the introduction time of TMA is 3000 ms; in step (3.2), the introduction time of ozone is 1500 ms.

[0076] Example 3

[0077] The difference from Example 1 is that in step (3.1), the introduction time of TMA is 4000 ms; in step (3.2), the introduction time of ozone is 2000 ms.

[0078] Example 4

[0079] The difference from Example 1 is that in step (3.1), the introduction time of TMA is 5000 ms.

[0080] Example 5

[0081] The difference from Example 1 is that in step (3.5), the ozone introduction time is 5000 ms.

[0082] Example 6

[0083] The difference from Example 1 is that in step (3.5), the ozone introduction time is 6000 ms.

[0084] Example 7

[0085] The difference from Example 1 is that in step (3.5), the ozone introduction time is 8000 ms.

[0086] Example 8

[0087] The difference from Example 1 is that in step (3.5), ozone is introduced into the reaction chamber at a flow rate of 5000 sccm.

[0088] Example 9

[0089] The difference from Example 1 is that in step (3.5), ozone is introduced into the reaction chamber at a flow rate of 7000 sccm.

[0090] Example 10

[0091] The difference from Example 1 is that in step (3.5), ozone is introduced into the reaction chamber at a flow rate of 8000 sccm.

[0092] Embodiment 11

[0093] The difference from Example 1 is that in step (3.4), the reaction chamber is vacuumed for 1500 ms after the first purge is completed; in step (3.6), the vacuum treatment time is 500 ms; in step (3.8), the vacuum treatment time is 1500 ms.

[0094] Example 12

[0095] The difference from Example 1 is that in step (3.4), the reaction chamber is vacuumed for 2000 ms after the first purge is completed; in step (3.6), the vacuum treatment time is 1000 ms; in step (3.8), the vacuum treatment time is 2000 ms.

[0096] Example 13

[0097] The difference from Example 1 is that in step (3.4), the reaction chamber is vacuumed for 1000 ms after the first purge is completed; in step (3.6), the vacuum treatment time is 1500 ms; in step (3.8), the vacuum treatment time is 1000 ms.

[0098] Embodiment 14

[0099] The difference from Example 1 is that the atomic layer deposition is performed 30 times, and each atomic layer deposition process includes the above steps (3.1) to (3.8).

[0100] Embodiment 15

[0101] The difference from Example 1 is that the atomic layer deposition is performed 34 times, and each atomic layer deposition process includes the above steps (3.1) to (3.8).

[0102] Example 16

[0103] The difference from Example 1 is that the atomic layer deposition is performed 38 times, and each atomic layer deposition process includes the above steps (3.1) to (3.8).

[0104] Embodiment 17

[0105] The difference from Example 1 is that the temperature of the preheating process is 180°C, and the temperature of the atomic layer deposition process is also 180°C. In step (3.1), the introduction rate of the aluminum source is 3000sccm, and the introduction time is 3000ms; in step (3.2), the introduction rate of ozone is 2000sccm, and the introduction time is 1500ms; in step (3.5), the introduction rate of ozone is 5000sccm, and the introduction time is 5000ms.

[0106] Embodiment 18

[0107] The difference from Example 1 is that the temperature of the preheating process is 200°C, and the temperature of the atomic layer deposition process is also 200°C. In step (3.1), the introduction rate of the aluminum source is 4000sccm, and the introduction time is 4000ms; in step (3.2), the introduction rate of ozone is 3000sccm, and the introduction time is 2000ms; in step (3.5), the introduction rate of ozone is 7000sccm, and the introduction time is 6000ms.

[0108] The aluminum oxide passivation films prepared in all the above Examples 2 to 18 of the present application are made into PERC cells, and the preparation method of the PERC cells is the same as that of Example 1.

[0109] Comparative Example 1

[0110] The difference from Example 1 is that: a traditional back passivation process is adopted, and ozone is first introduced to oxidize the silicon wafer during each atomic layer deposition process, wherein the ozone introduction rate is 3000sccm, the introduction time is 10min, and then ozone is introduced for reaction, thereby forming a back aluminum oxide passivation layer 5 with a thickness of 3 to 6nm and a back silicon oxide passivation layer 7 with a thickness of 3 to 4nm on the surface of the silicon wafer.

[0111] like Figure 2 As shown, the PERC cell prepared in Comparative Example 1 includes a front SiOx layer 1, a front SiON layer 2, a front SiNx layer 3, a silicon substrate layer 4, a back silicon oxide passivation layer 7, a back aluminum oxide passivation layer 5 and a back SiNx layer 6 which are stacked in sequence. Compared with Example 1, in the PERC cell structure of Comparative Example 1, a back silicon oxide passivation layer 7 is also generated by reaction on the side of the silicon substrate layer 4 close to the back aluminum oxide passivation layer 5.

[0112] Comparative Example 2

[0113] The difference from Example 1 is that an aluminum oxide passivation film is deposited on the surface of the silicon wafer by CVD method, TMA and ozone are introduced simultaneously during the chemical deposition process, and the inner cavity volume of the chemical deposition equipment (Songyu Technology ALD3.0 atomic layer deposition equipment) is 72.6m 3, set the rate of TMA entering the reaction chamber to 3000 sccm, and the rate of ozone entering the reaction chamber to 2000 sccm.

[0114] The thickness of the aluminum oxide passivation film prepared in the present application is measured by an ellipsometer. The photoelectric conversion efficiency test process includes: Halm test machine test conversion efficiency (conditions: light intensity: 1000W / cm 2 ; Test temperature: 25℃; Silicon wafer area: 33015mm 2 ) and grading, the EL test method is as follows: Peide EL test machine test machine and classification and calculation of various proportions.

[0115] The thickness, EL "black spot" ratio and yield of the aluminum oxide passivation film obtained in all the above embodiments and comparative examples of the present application are shown in Table 1, and the electrochemical properties of the obtained PERC battery are shown in Table 2.

[0116] Table 1

[0117] Aluminum oxide passivation film thickness (nm) EL black spot ratio (%) Yield (%) Example 1 3.35 0.30 99.14 Example 2 3.01 0.51 98.85 Example 3 3.52 0.52 98.80 Example 4 3.65 0.65 98.78 Example 5 3.54 0.64 98.80 Example 6 3.68 0.80 98.50 Example 7 3.85 0.81 98.45 Example 8 3.80 0.86 98.76 Example 9 3.75 0.85 98.68 Example 10 3.85 0.90 98.52 Embodiment 11 3.43 0.86 98.68 Example 12 3.40 0.50 98.99 Example 13 3.50 0.65 98.85 Embodiment 14 3.15 0.42 98.92 Embodiment 15 3.65 0.60 98.84 Example 16 4.01 0.55 98.75 Embodiment 17 3.85 0.64 98.94 Embodiment 18 3.45 0.54 98.89 Comparative Example 1 3.74 0.85 98.10 Comparative Example 2 4.84 1.51 94.61

[0118] Table 2

[0119] Voc / V Jsc / A FF PCE / % Example 1 0.6693 13.611 81.24 23.42 Example 2 0.6683 13.608 81.22 23.39 Example 3 0.6685 13.615 81.20 23.40 Example 4 0.6686 13.613 81.21 23.40 Example 5 0.6689 13.612 81.25 23.41 Example 6 0.6684 13.615 81.19 23.39 Example 7 0.6686 13.618 80.19 23.40 Example 8 0.6690 13.608 81.22 23.41 Example 9 0.6692 13.607 81.21 23.41 Example 10 0.6686 13.609 81.20 23.39 Embodiment 11 0.6689 13.607 81.19 23.39 Example 12 0.6688 13.609 81.21 23.40 Example 13 0.6685 13.608 81.20 23.38 Embodiment 14 0.6684 13.611 81.21 23.39 Embodiment 15 0.6686 13.612 81.23 23.40 Example 16 0.6680 13.615 81.26 23.39 Embodiment 17 0.6684 13.608 81.18 23.38 Embodiment 18 0.6689 13.609 81.19 23.40 Comparative Example 1 0.6680 13.610 81.15 23.29 Comparative Example 2 0.6620 13.581 80.90 22.00

[0120] From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the following technical effects: compared with first introducing ozone into the reaction chamber, the present application adopts a method of first introducing trimethylaluminum into the reaction chamber and then introducing ozone, which can inhibit the generation of silicon oxide first, and first generate an aluminum oxide passivation film on one side of the semiconductor substrate material. The passivation effect can be improved, thereby improving the photoelectric conversion efficiency of the PERC cell; at the same time, the aluminum oxide deposition time can be shortened, and the introduction of impurities can be inhibited to cause the aluminum oxide passivation film to produce EL black spots, which can improve the product yield and is conducive to mass production.

[0121] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0122] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material, It is characterized in that The method comprises: Atomic layer deposition is performed at least twice on one side surface of the semiconductor substrate material to obtain the aluminum oxide passivation film; the atomic layer deposition process is carried out in a reaction chamber of an atomic layer deposition device, wherein each time the atomic layer deposition is performed, an aluminum source is first introduced into the reaction chamber and then ozone is introduced.

2. The method for forming an aluminum oxide passivation film on a semiconductor substrate material surface according to claim 1, It is characterized in that Each of the atomic layer deposition processes comprises the following steps: Step S21, introducing the aluminum source into the reaction chamber through an aluminum source supply pipeline, the introduction time being 3000-4000 ms; Step S22, after the aluminum source is introduced, the ozone is introduced into the reaction chamber through an ozone supply pipe, and the introduction time is 1500-2000 ms; Step S23, using inert gas to purge the aluminum source supply pipeline and the ozone supply pipeline for the first time respectively; Step S24, performing a first vacuuming process on the reaction chamber; Step S25, introducing the ozone into the reaction chamber, setting the introduction time to 5000-6000 ms; Step S26, performing a second vacuuming process on the reaction chamber; Step S27, using inert gas to purge the aluminum source supply pipeline and the ozone supply pipeline for a second time respectively; Step S28, performing a third vacuuming process on the reaction chamber; Preferably, the aluminum source is trimethylaluminum; Preferably, the semiconductor substrate material is a p-type silicon substrate material.

3. The method for forming an aluminum oxide passivation film on a semiconductor substrate material surface according to claim 2, It is characterized in that The volume of the reaction chamber is 72-73 m 3 In step S21, the aluminum source is introduced at a rate of 3000 to 4000 sccm; and / or In step S22, the ozone introduction rate is 2000-3000 sccm; and / or, In the step S23, the inert gas introduction rate during the first purge is independently selected from 8000 to 10000 sccm; and / or, In the step S24, the first vacuuming treatment is performed for 1500-2000 ms to make the vacuum degree of the reaction chamber 1-2 Pa; and / or, In the step S25, the ozone introduction rate is 5000-7000 sccm; and / or, In the step S26, the second vacuuming treatment is performed for 500 to 1000 ms to make the vacuum degree of the reaction chamber 1 to 2 Pa; and / or, In the step S27, the inert gas introduction rate during the second purge is independently selected from 8000 to 10000 sccm; and / or, In the step S28, the third vacuuming treatment is performed for 1500-2000 ms to make the vacuum degree of the reaction chamber 1-2 Pa.

4. The method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material according to claim 2 or 3, It is characterized in that The method comprises: performing 30 to 34 atomic layer depositions on a surface of one side of the semiconductor substrate material to obtain the aluminum oxide passivation film.

5. The method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material according to any one of claims 2 to 4, It is characterized in that Before performing the atomic layer deposition process, the method further includes a process of preheating the semiconductor substrate material; Preferably, the temperature of the atomic layer deposition process is lower than the temperature of the preheating process, and the temperature difference between the two is ≤5°C.

6. The method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material according to claim 5, It is characterized in that The temperature of the preheating process is 180-200° C., the time is 240-270 seconds, and the heating rate is 6-10° C. / min.

7. The method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material according to claim 6, It is characterized in that When the temperature of the preheating process is 180-190°C and the temperature of the atomic layer deposition process is 180-190°C, in the step S21, the introduction rate of the aluminum source is 3000-3300sccm, and the introduction time is 3000-3300ms, in the step S22, the introduction rate of the ozone is 2000-2300sccm, and the introduction time is 1500-1700ms, and in the step S25, the introduction rate of the ozone is 5000-6000sccm, and the introduction time is 5000-5300ms; When the temperature of the preheating process is 191-195° C. and the temperature of the atomic layer deposition process is 191-195° C., in the step S21, the introduction rate of the aluminum source is 3300-3700 sccm, and the introduction time is 3300-3700 ms, in the step S22, the introduction rate of the ozone is 2300-2700 sccm, and the introduction time is 1700-1800 ms, and in the step S25, the introduction rate of the ozone is 6000-6500 sccm, and the introduction time is 5300-5500 ms; When the temperature of the preheating process is 196-200°C and the temperature of the atomic layer deposition process is 196-200°C, in the step S21, the introduction rate of the aluminum source is 3700-4000sccm, and the introduction time is 3700-4000ms. In the step S22, the introduction rate of the ozone is 2700-3000sccm, and the introduction time is 1800-2000ms. In the step S25, the introduction rate of the ozone is 6500-7000sccm, and the introduction time is 5500-6000ms.

8. A method for preparing a PERC cell, It is characterized in that The method for preparing the PERC cell comprises the method for forming an aluminum oxide passivation film on the surface of a semiconductor substrate material according to any one of claims 1 to 7.

9. A PERC cell, It is characterized in that The PERC cell is prepared by the PERC cell preparation method according to claim 8.

10. The PERC cell according to claim 9, It is characterized in that The PERC cell comprises an aluminum oxide passivation film, and the thickness of the aluminum oxide passivation film is 2 to 5 nm.

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