Preparation method of aluminum oxide passivation layer, aluminum oxide passivation layer and TBC battery

Abstract

The invention provides a preparation method of an aluminum oxide passivation layer, the aluminum oxide passivation layer and a TBC battery, and relates to the technical field of solar batteries. The preparation method of the aluminum oxide passivation layer comprises the following steps: introducing a mixed gas of chlorine dioxide, hydrogen chloride and hypochlorous acid into the silicon substrate, and carrying out first pretreatment; introducing mixed gas of hydrogen and argon, and carrying out secondary pretreatment; introducing mixed gas of nitrogen, oxygen and water vapor, and carrying out third pretreatment; and after the pretreatment is completed, depositing an aluminum oxide passivation layer on the silicon substrate. According to the preparation method, the problem that in the prior art, aluminum oxide is directly deposited on a silicon substrate after texturing, and the fitting degree of aluminum oxide and the textured surface is poor due to poor uniformity of a natural oxide layer is solved, the passivation performance of the prepared aluminum oxide passivation layer is effectively improved, and therefore the open voltage and the conversion efficiency of a TBC battery prepared from the aluminum oxide passivation layer are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a preparation method of an aluminum oxide passivation layer, the aluminum oxide passivation layer and a TBC cell. BACKGROUND

[0002] After the TBC cell is textured, it is exposed to the environment, and an irregular natural oxidation layer with impurities is easily formed. The reasons include: the textured TBC silicon wafer surface has a huge specific surface area and extremely high chemical reactivity (especially dangling bonds and high curvature regions), which makes it extremely rapid and unevenly oxidize when exposed to an air environment containing oxygen, water vapor and various pollutants. At the same time, environmental pollutants will be adsorbed and embedded into the growing oxide layer, which results in the natural oxidation layer formed having the characteristics of uneven thickness, loose and disordered structure, rich in defects and impurities, rough interface, etc.

[0003] However, in the prior art, the aluminum oxide passivation layer is deposited on the surface of the textured silicon wafer by atomic layer deposition (ALD). Although atomic layer deposition (ALD) has excellent step coverage and conformality (can uniformly cover complex topography), the film quality is highly dependent on the nucleation of the initial few cycles. The natural oxidation layer of the textured cell wafer has poor uniformity. If the initial substrate surface is uneven, contaminated or has weakly bonded areas, etc., it will cause poor adhesion of the deposited aluminum oxide to the textured surface, or the appearance of pyramid valleys, contaminant edges or weak / porous oxidation layer, which may result in incomplete local coverage, discontinuous film, etc. Even at the oxidation layer thickness mutation or contaminant protrusion, the aluminum oxide passivation layer is prone to stress concentration, resulting in microcracks or peeling, which in turn reduces the passivation performance of the passivation layer, and ultimately leads to a decrease in the open voltage and conversion efficiency of the prepared TBC cell.

[0004] Therefore, the present application is proposed. SUMMARY

[0005] The present application aims to provide a preparation method of an aluminum oxide passivation layer, the aluminum oxide passivation layer and a TBC cell, which solves the problem of poor adhesion of the deposited aluminum oxide to the textured surface due to the poor uniformity of the natural oxidation layer after the silicon substrate is textured in the prior art, effectively improves the passivation performance of the prepared aluminum oxide passivation layer, and significantly improves the open voltage and conversion efficiency of the TBC cell prepared therefrom.

[0006] In order to achieve the above purpose, the following technical solutions are proposed:

[0007] In a first aspect, the present application provides a preparation method of an aluminum oxide passivation layer, comprising:

[0008] The first pretreatment is performed by introducing a mixed gas of chlorine dioxide, hydrogen chloride and hypochlorous acid into the silicon substrate; the second pretreatment is performed by introducing a mixed gas of hydrogen and argon; the third pretreatment is performed by introducing a mixed gas of nitrogen, oxygen and water vapor; and an aluminum oxide passivation layer is deposited on the silicon substrate after the pretreatments.

[0009] Further, the first pretreatment, the second pretreatment and the third pretreatment are performed by ALD process.

[0010] Further, in the first pretreatment, the flow rate ratio of the chlorine dioxide, the hydrogen chloride and the hypochlorous acid is (0.5-1.5):(1-3):(0.5-1.5).

[0011] Further, in the first pretreatment, the flow rate of the hydrogen chloride is 1-3 slm.

[0012] Further, the temperature of the first pretreatment is 300-400℃.

[0013] Further, the time of the first pretreatment is 1-3 min.

[0014] Further, in the second pretreatment, the flow rate ratio of the hydrogen and the argon is (0.5-1.5):(1-3).

[0015] Further, in the second pretreatment, the flow rate of the argon is 3-5 slm.

[0016] Further, the temperature of the second pretreatment is 300-400℃.

[0017] Further, the time of the second pretreatment is 3-8 min.

[0018] Further, between the second pretreatment and the third pretreatment, a nitrogen blowing and vacuuming are further included.

[0019] Further, in the blowing, the flow rate of the nitrogen is 13-18 slm.

[0020] Further, the time of the blowing is 5-18 min.

[0021] Further, in the third pretreatment, the flow rate ratio of the nitrogen, the oxygen and the water vapor is (0.5-1.5):(2-4):(1-3).

[0022] Further, in the third pretreatment, the flow rate of the oxygen is 0.3-1 slm.

[0023] Further, the temperature of the third pretreatment is 300-400℃.

[0024] Further, the third pre-treatment time is 1-5 min.

[0025] Further, the deposition of the aluminum oxide passivation layer is performed by ALD process.

[0026] Further, the deposition of the aluminum oxide passivation layer comprises the following steps:

[0027] The aluminum oxide passivation layer is obtained by alternately introducing the aluminum-containing precursor gas and the oxidizing agent into the pre-treated silicon substrate to perform cyclic deposition.

[0028] In a second aspect, the present application provides an aluminum oxide passivation layer, which is prepared by the preparation method of the first aspect.

[0029] In a third aspect, the present application provides a TBC battery, which comprises the aluminum oxide passivation layer of the second aspect or the aluminum oxide passivation layer prepared by the preparation method of the first aspect.

[0030] Further, the TBC battery comprises an N-type crystalline silicon substrate.

[0031] The back surface of the N-type crystalline silicon substrate comprises a P region, an N region and an isolation region between the P region and the N region, and the P region and the N region are arranged alternately; the P region comprises, from inside to outside, a tunneling oxide layer, a P-type doped polysilicon layer, an aluminum oxide passivation layer and a silicon nitride passivation layer; the N region comprises, from inside to outside, a tunneling oxide layer, an N-type doped polysilicon layer, an aluminum oxide passivation layer and a silicon nitride passivation layer; the P region is provided with a P region electrode, and the N region is provided with an N region electrode.

[0032] The front surface of the N-type crystalline silicon substrate has a pyramid texture structure; and the front surface of the N-type crystalline silicon substrate comprises, from inside to outside, an aluminum oxide passivation layer, a silicon nitride passivation layer and a silicon oxide passivation layer.

[0033] In a fourth aspect, the present application provides a preparation method of a TBC battery, which comprises:

[0034] (1) depositing a tunneling oxide layer and an intrinsic amorphous silicon layer on the back surface of an N-type crystalline silicon substrate;

[0035] (2) performing boron diffusion on the back surface of the silicon substrate obtained in step (1) to form a boron-doped polysilicon layer;

[0036] (3) sequentially performing first patterning, BSG around plating removal, alkali etching, deposition of a tunneling oxide layer and an intrinsic amorphous silicon layer, phosphorus diffusion, second patterning, PSG around plating removal, texturing, passivation treatment, electrode printing and light injection on the silicon substrate subjected to boron diffusion in step (2) to obtain the TBC battery.

[0037] The passivation treatment comprises: depositing an aluminum oxide passivation layer on both sides of the silicon substrate after texturing, depositing a silicon nitride passivation layer on the back side, depositing a silicon nitride passivation layer on the front side, and depositing a silicon oxide passivation layer; wherein the aluminum oxide passivation layer is deposited on both sides by using the preparation method of the first aspect.

[0038] Compared with the prior art, the present application has the following beneficial effects:

[0039] (1) The pretreatment step in the preparation method of the aluminum oxide passivation layer can effectively remove the adsorbed contaminant particles in the oxide layer on the silicon substrate after texturing, improve the cleanliness of the silicon wafer surface, thereby reducing the oxidation defects caused by the introduction of metal impurities, and effectively removing the irregular natural oxide layer.

[0040] (2) The pretreatment step in the preparation method of the aluminum oxide passivation layer can introduce a weakly oxidized surface, which is more conducive to the formation of a Si-O-Al structure with low interface defect density, and the low-valence oxidized surface promotes the formation of an octahedral AlO6 structure, enhances the negative fixed charge density, thereby reducing the recombination current density of the TBC cell, and significantly improving the open-circuit voltage and conversion efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the specific embodiments or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0042] Figure 1 It is a structural schematic diagram of the TBC cell of the present application.

[0043] Figure 2 It is a process flow chart of the preparation method of the TBC cell of the present application.

[0044] Figure 3 It is a structural schematic diagram of the cell wafer obtained by boron diffusion in the preparation method of the TBC cell of the present application.

[0045] Figure 4 It is a structural schematic diagram of the cell wafer obtained by the first patterning in the preparation method of the TBC cell of the present application.

[0046] Figure 5 It is a structural schematic diagram of the cell wafer obtained by removing BSG and alkaline etching in the preparation method of the TBC cell of the present application.

[0047] Figure 6A structure diagram of a battery piece obtained by phosphorus diffusion in a preparation method of the TBC battery.

[0048] Figure 7 A structure diagram of a battery piece obtained by second patterning in the preparation method of the TBC battery.

[0049] Figure 8 A structure diagram of a battery piece obtained by PSG removal and texturing in the preparation method of the TBC battery.

[0050] In the figure, 10 represents an N-type crystalline silicon substrate, 20 represents a tunneling oxide layer, 31 represents a P-type doped polysilicon layer, 32 represents an N-type doped polysilicon layer, 40 represents a BSG layer, 41 represents a PSG layer, 60 represents an aluminum oxide passivation layer, 61 represents a silicon nitride passivation layer, 62 represents a silicon oxide passivation layer, 71 represents a P-zone electrode, and 72 represents an N-zone electrode. DETAILED DESCRIPTION

[0051] Unless otherwise defined, scientific and technical terms used in connection with the present application shall have the meanings that are commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear; however, in the event of any latent ambiguity, definitions provided herein take precedent over any dictionary or extrinsic definition. Throughout this application, unless otherwise indicated, the use of the term "or" means "and / or". Furthermore, use of the term "including" as well as other forms such as "include", "includes" for indicating components, items or elements of items is not limiting.

[0052] It should be noted that specific details are set forth in the following description in order to provide a thorough understanding of the application. However, the application can be practiced without many of the details set forth in this description, which are provided to give a thorough description of the claimed application. Therefore, the present application is not limited to the details below and can be practiced with other ways than those described below.

[0053] The technical solutions of the present application will be described clearly and completely below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0054] In a first aspect, the present application provides a preparation method of an aluminum oxide passivation layer, which comprises:

[0055] The silicon substrate is subjected to a first pretreatment by introducing a mixed gas of chlorine dioxide, hydrogen chloride and hypochlorous acid, a second pretreatment by introducing a mixed gas of hydrogen and argon, and a third pretreatment by introducing a mixed gas of nitrogen, oxygen and water vapor. After the pretreatments, an aluminum oxide passivation layer is deposited on the silicon substrate.

[0056] In the present application, the surface is pretreated before depositing aluminum oxide: first, a mixed gas of chlorine dioxide (ClO2), hydrogen chloride (HCl) and hypochlorous acid (HClO) is introduced to perform the first pretreatment; the chlorine atom can purify the activity of metal ions such as sodium ions, the hydrogen atom can passivate the surface dangling bonds of the oxide layer, and the three gases can remove the adsorbed impurity particles in the oxide layer at the same time, so that the cleanliness of the silicon wafer surface is improved, thereby reducing the oxidation defects caused by the introduction of metal impurities. Next, a mixed gas of hydrogen (H2) and argon (Ar) is introduced to perform the second pretreatment; effectively removing the irregular natural oxide layer. Finally, a mixed gas of nitrogen (N2), oxygen (O2) and water vapor (H2O) is introduced to perform the third pretreatment, which introduces a weakly oxidized surface (Si 2+ / Si 3+ ) which is more conducive to the formation of a Si-O-Al structure with a low interface defect density (~1×10 11 eV -1 cm -2 ), and the low-valence oxidation state surface promotes the formation of an octahedral AlO6 structure, enhances the negative fixed charge density, and can reduce the recombination current density (J) of the TBC battery containing the passivation layer prepared by the method, and improve the open circuit voltage and conversion efficiency.

[0057] As an optional implementation, the first pretreatment, the second pretreatment and the third pretreatment are performed by ALD process.

[0058] As an optional implementation, in the first pretreatment, the flow ratio of chlorine dioxide, hydrogen chloride and hypochlorous acid is (0.5-1.5):(1-3):(0.5-1.5);

[0059] Among them, the chlorine dioxide (ClO2): “0.5-1.5” may be 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, etc.

[0060] Among them, hydrogen chloride (HCl): “1-3” may be 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, etc.

[0061] Among them, hypochlorous acid (HClO): “0.5-1.5” may be 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, etc.

[0062] As an optional embodiment, in the first pretreatment, the flow rate of the hydrogen chloride (HCl) is 1-3 slm, for example, it can be 1 slm, 1.2 slm, 1.4 slm, 1.6 slm, 1.8 slm, 2 slm, 2.2 slm, 2.4 slm, 2.6 slm, 2.8 slm, 3 slm, etc.

[0063] As an optional embodiment, the temperature of the first pretreatment is 300-400°C, for example, it can be 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, etc.

[0064] As an optional embodiment, the time of the first pretreatment is 1-3 min, for example, it can be 1 min, 1.2 min, 1.4 min, 1.6 min, 1.8 min, 2 min, 2.2 min, 2.4 min, 2.6 min, 2.8 min, 3 min, etc.

[0065] As an optional embodiment, in the second pretreatment, the flow rate ratio of the hydrogen (H2) and argon (Ar) is (0.5-1.5):(1-3);

[0066] Among them, the flow rate of hydrogen (H2) is “0.5-1.5”, for example, it can be 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, etc.

[0067] Among them, the flow rate of hydrogen chloride (Ar) is “1-3”, for example, it can be 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, etc.

[0068] As an optional embodiment, in the second pretreatment, the flow rate of the argon is 3-5 slm, for example, it can be 3 slm, 3.2 slm, 3.4 slm, 3.6 slm, 3.8 slm, 4 slm, 4.2 slm, 4.4 slm, 4.6 slm, 4.8 slm, 5 slm, etc.

[0069] As an optional embodiment, the temperature of the second pretreatment is 300-400°C, for example, it can be 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, etc.

[0070] As an optional embodiment, the time of the second pretreatment is 3-8 minutes, for example, it can be 3 minutes, 3.2 minutes, 3.4 minutes, 3.6 minutes, 3.8 minutes, 4 minutes, 4.2 minutes, 4.4 minutes, 4.6 minutes, 4.8 minutes, 5 minutes, 5.2 minutes, 5.4 minutes, 5.6 minutes, 5.8 minutes, 6 minutes, 6.2 minutes, 6.4 minutes, 6.6 minutes, 6.8 minutes, 7 minutes, 7.2 minutes, 7.4 minutes, 7.6 minutes, 7.8 minutes, 8 minutes, etc.

[0071] As an optional embodiment, between the second pretreatment and the third pretreatment, nitrogen gas purging and vacuum extraction (the purpose is to remove residual gas and reactants) are further included.

[0072] As an optional embodiment, in the purging, the flow rate of the nitrogen gas is 13-18 slm, for example, it can be 13 slm, 13.5 slm, 14 slm, 14.5 slm, 15 slm, 15.5 slm, 16 slm, 16.5 slm, 17 slm, 17.5 slm, 18 slm, etc.

[0073] As an optional embodiment, the time of the purging is 5-18 minutes, for example, it can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, etc.

[0074] Further, in the third pretreatment, the flow rate ratio of the nitrogen gas, the oxygen gas, and the water vapor is (0.5-1.5):(2-4):(1-3);

[0075] Among them, the nitrogen gas (N2): “0.5-1.5” can be 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, etc.

[0076] Among them, the oxygen gas (HCl): “2-4” can be 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 4.6, 4.8, 5, etc.

[0077] Among them, the water vapor (H2O): “1-3” can be 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, etc.

[0078] As an optional embodiment, in the third pretreatment, the flow rate of the oxygen is 0.3-1 slm, for example, it can be 0.3 slm, 0.4 slm, 0.5 slm, 0.6 slm, 0.7 slm, 0.8 slm, 0.9 slm, 1 slm, etc.

[0079] As an optional embodiment, the temperature of the third pretreatment is 300-400℃, for example, it can be 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, etc.

[0080] As an optional embodiment, the time of the third pretreatment is 1-5 min, for example, it can be 1 min, 1.2 min, 1.4 min, 1.6 min, 1.8 min, 2 min, 2.2 min, 2.4 min, 2.6 min, 2.8 min, 3 min, 3.2 min, 3.4 min, 3.6 min, 3.8 min, 4 min, 4.2 min, 4.4 min, 4.6 min, 4.8 min, 5 min, etc.

[0081] As an optional embodiment, the deposition of the alumina passivation layer is performed by using an ALD process.

[0082] As an optional embodiment, the deposition of the alumina passivation layer comprises the following steps:

[0083] The alumina passivation layer is obtained by alternately introducing trimethylaluminum and water vapor into the pretreated silicon substrate for cyclic deposition.

[0084] As an optional embodiment, the temperature for the deposition of the alumina passivation layer is 200-400℃, for example, it can be 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, etc.

[0085] As an optional embodiment, the number of times for the cyclic deposition of the alumina passivation layer is 20-50 times, for example, it can be 20 times, 22 times, 24 times, 25 times, 26 times, 28 times, 30 times, 32 times, 34 times, 35 times, 36 times, 38 times, 40 times, 42 times, 44 times, 45 times, 46 times, 48 times, 50 times, etc.

[0086] As an optional embodiment, the single cycle of the deposition of the alumina passivation layer comprises the cyclic deposition of the precursor introduction to the surface of the substrate to be deposited, the first purification, the oxidation, and the second purification.

[0087] As an optional embodiment, the single-cycle deposition of the aluminum oxide passivation layer specifically comprises:

[0088] ① precursor introduction: introducing an Al-containing precursor gas;

[0089] ②purification: introducing a purification gas to remove unreacted Al-containing precursor gas and / or byproducts;

[0090] ③ oxidation: introducing an oxidant;

[0091] ④purification: introducing a purification gas to remove unreacted oxidant and / or byproducts.

[0092] As an optional embodiment, in step ①, the flow rate of the Al-containing precursor gas is 14-16 slm, for example, it can be 14 slm, 14.5 slm, 15 slm, 15.5 slm, 16 slm, etc.

[0093] As an optional embodiment, in step ①, the Al-containing precursor gas comprises trimethylaluminum (TMA).

[0094] As an optional embodiment, in step ②, the flow rate of the purification gas is 4-6 slm, for example, it can be 4 slm, 4.5 slm, 5 slm, 5.5 slm, 6 slm, etc.

[0095] As an optional embodiment, in step ②, the purification gas comprises nitrogen.

[0096] As an optional embodiment, in step ③, the flow rate of the oxidant is 14-16 slm, for example, it can be 14 slm, 14.5 slm, 15 slm, 15.5 slm, 16 slm, etc.

[0097] As an optional embodiment, in step ③, the oxidant comprises water vapor (H2O).

[0098] As an optional embodiment, in step ④, the flow rate of the purification gas is 4-6 slm, for example, it can be 4 slm, 4.5 slm, 5 slm, 5.5 slm, 6 slm, etc.

[0099] As an optional embodiment, in step ④, the purification gas comprises nitrogen.

[0100] As an optional embodiment, the thickness of the aluminum oxide passivation layer is 1-10 nm, for example, it can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, etc.

[0101] In a second aspect, the present application provides an aluminum oxide passivation layer prepared by the preparation method of the first aspect.

[0102] In a third aspect, the present application provides a TBC cell comprising the aluminum oxide passivation layer of the second aspect or the aluminum oxide passivation layer prepared by the preparation method of the first aspect.

[0103] As an optional embodiment, as shown in Figure 1 The TBC cell comprises an N-type crystalline silicon substrate 10, wherein the back surface of the N-type crystalline silicon substrate 10 comprises a P region, an N region and an isolation region between the P region and the N region, and the P region and the N region are arranged alternately; the P region comprises, from inside to outside, a tunneling oxide layer 20, a P-type doped polysilicon layer 31, an aluminum oxide passivation layer 60 and a silicon nitride passivation layer 61; the N region comprises, from inside to outside, a tunneling oxide layer 20, an N-type doped polysilicon layer 32, an aluminum oxide passivation layer 60 and a silicon nitride passivation layer 61; the P region is provided with a P region electrode 71, and the N region is provided with an N region electrode 72; wherein the front surface of the N-type crystalline silicon substrate 10 has a pyramid texture structure; and the front surface of the N-type crystalline silicon substrate comprises, from inside to outside, an aluminum oxide passivation layer 60, a silicon nitride passivation layer 61 and a silicon oxide passivation layer 62.

[0104] In a fourth aspect, the present application provides a preparation method of a TBC cell, as shown in Figure 2 The preparation method of the TBC cell comprises the following steps:

[0105] (1) depositing a tunneling oxide layer and an intrinsic amorphous silicon layer on the back surface of an N-type crystalline silicon substrate;

[0106] (2) performing boron diffusion on the back surface of the silicon substrate obtained in step (1) to form a boron-doped polysilicon layer;

[0107] (3) sequentially performing first patterning, BSG around plating removal, alkali etching, depositing a tunneling oxide layer and an intrinsic amorphous silicon layer, phosphorus diffusion, second patterning, PSG around plating removal, texturing, passivation treatment, printing electrodes and light injection on the silicon substrate subjected to boron diffusion in step (2) to obtain the TBC cell.

[0108] The passivation treatment comprises depositing an aluminum oxide passivation layer on both surfaces of the silicon substrate after texturing, depositing a silicon nitride passivation layer on the back surface, depositing a silicon nitride passivation layer and a silicon oxide passivation layer on the front surface; and the deposition of the aluminum oxide passivation layer on both surfaces is performed by the preparation method of the first aspect.

[0109] As an optional implementation, in step (1), the deposition of the tunneling oxide layer and the intrinsic amorphous silicon layer comprises: sequentially depositing the tunneling oxide layer and the intrinsic amorphous silicon layer on the back surface of the silicon substrate by the LPCVD method.

[0110] As an optional implementation, in step (1), the thickness of the tunneling oxide layer is 1.0-2.5 nm, for example, it can be 1.0 nm, 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm, 2.0 nm, 2.1 nm, 2.2 nm, 2.3 nm, 2.4 nm, 2.5 nm, etc.; the temperature for depositing the tunneling oxide layer is 500-650℃, for example, it can be 500℃, 520℃, 540℃, 550℃, 560℃, 580℃, 600℃, 620℃, 640℃, 650℃, etc.; the time for depositing the tunneling oxide layer is 20-80 min, for example, it can be 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, etc.

[0111] As an optional implementation, in step (1), the thickness of the intrinsic amorphous silicon layer is 200-400 nm, for example, it can be 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, 300 nm, 320 nm, 340 nm, 360 nm, 380 nm, 400 nm, etc.; the temperature for depositing the intrinsic amorphous silicon layer is 500-650℃, for example, it can be 500℃, 520℃, 540℃, 550℃, 560℃, 580℃, 600℃, 620℃, 640℃, 650℃, etc.; the time for depositing the intrinsic amorphous silicon layer is 50-100 min, for example, it can be 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, 90 min, 95 min, 100 min, etc.

[0112] As an optional implementation, in step (2), the boron diffusion comprises: diffusing phosphorus into the silicon substrate after step (1) by passing BCl3, O2, N2 mixed gas to obtain a silicon substrate with a boron-doped polysilicon layer.

[0113] As an optional implementation, in step (2), the process parameters of the boron diffusion include: BCl3 flow rate is 200-400 sccm, for example, it can be 200 sccm, 220 sccm, 240 sccm, 260 sccm, 280 sccm, 300 sccm, 320 sccm, 340 sccm, 360 sccm, 380 sccm, 400 sccm, etc.; O2 flow rate is 700-1000 sccm, for example, it can be 700 sccm, 720 sccm, 740 sccm, 760 sccm, 780 sccm, 800 sccm, 820 sccm, 840 sccm, 860 sccm, 880 sccm, 900 sccm, 920 sccm, 940 sccm, 960 sccm, 980 sccm, 1000 sccm, etc.; N2 flow rate is 2500-3000 sccm, for example, it can be 2500 sccm, 2550 sccm, 2600 sccm, 2650 sccm, 2700 sccm, 2750 sccm, 2800 sccm, 2850 sccm, 2900 sccm, 2950 sccm, 3000 sccm, etc.; deposition temperature is 800-1000℃, for example, it can be 800℃, 820℃, 840℃, 860℃, 880℃, 900℃, 920℃, 940℃, 960℃, 980℃, 1000℃, etc.; deposition time is 1-2h, for example, it can be 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2h, etc.; square resistance is 100-200Ω, for example, it can be 100Ω, 110Ω, 120Ω, 130Ω, 140Ω, 150Ω, 160Ω, 170Ω, 180Ω, 190Ω, 200Ω, etc.

[0114] As an optional implementation, in step (3), the first patterning includes: removing part of the BSG layer (the BSG layer of the subsequent Gap region+N region) on the back surface of the silicon substrate obtained in step (2), to form a patterned groove.

[0115] As an optional implementation, the first patterning is performed by picosecond laser.

[0116] As an optional implementation, the depth of the patterned groove formed by the first patterning is 30-80nm, for example, it can be 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, etc.

[0117] As an optional implementation, the width of the first-time formed patterned groove is 400-600 μm, for example, it can be 400 μm, 420 μm, 440 μm, 460 μm, 480 μm, 500 μm, 520 μm, 540 μm, 560 μm, 580 μm, 600 μm, etc.

[0118] As an optional implementation, in step (3), the BSG around plating and alkali stripping include: chain wet removal of the front BSG around plating, tank polishing removal of the front around plating and the P-type doped polysilicon layer and the tunneling oxide layer in the back patterned groove area, the depth of the patterned groove is increased to 2-3 μm, for example, it can be 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3 μm, etc.

[0119] As an optional implementation, in step (3), the deposition of the tunneling oxide layer and the intrinsic amorphous silicon layer includes: deposition of the secondly formed tunneling oxide layer and the intrinsic amorphous silicon layer by LPCVD method.

[0120] As an optional implementation, in step (3), the thickness of the tunneling oxide layer is 1.0-2.5 nm, for example, it can be 1.0 nm, 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm, 2.0 nm, 2.1 nm, 2.2 nm, 2.3 nm, 2.4 nm, 2.5 nm, etc.

[0121] As an optional implementation, in step (3), the temperature for depositing the tunneling oxide layer is 500-650 ℃, for example, it can be 500 ℃, 520 ℃, 540 ℃, 550 ℃, 560 ℃, 580 ℃, 600 ℃, 620 ℃, 640 ℃, 650 ℃, etc.

[0122] As an optional implementation, in step (3), the time for depositing the tunneling oxide layer is 20-80 min, for example, it can be 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, etc.

[0123] As an optional implementation, in step (3), the thickness of the intrinsic amorphous silicon layer is 100-300 nm, for example, it can be 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, 300 nm, etc.

[0124] As an optional embodiment, in step (3), the temperature for depositing the intrinsic amorphous silicon layer is 500-650℃, for example, it can be 500℃, 520℃, 540℃, 550℃, 560℃, 580℃, 600℃, 620℃, 640℃, 650℃, etc.

[0125] As an optional embodiment, in step (3), the time for depositing the intrinsic amorphous silicon layer is 50-100min, for example, it can be 50min, 55min, 60min, 65min, 70min, 75min, 80min, 85min, 90min, 95min, 100min, etc.

[0126] As an optional embodiment, in step (3), the phosphorus diffusion includes: introducing POCl3, O2 and N2 mixed gas into the silicon substrate after secondary deposition to perform phosphorus diffusion, so as to obtain a silicon substrate with a phosphorus-doped polysilicon layer.

[0127] As an optional implementation, in step (3), during the phosphorus diffusion, the flow rate of the POCl3 is 1000-2000 sccm, for example, it can be 1000 sccm, 1100 sccm, 1200 sccm, 1300 sccm, 1400 sccm, 1500 sccm, 1600 sccm, 1700 sccm, 1800 sccm, 1900 sccm, 2000 sccm, etc.; the flow rate of the O2 is 500-1000 sccm, for example, it can be 500 sccm, 550 sccm, 600 sccm, 650 sccm, 700 sccm, 725 sccm, 750 sccm, 775 sccm, 800 sccm, 825 sccm, 850 sccm, 875 sccm, 900 sccm, 925 sccm, 950 sccm, 975 sccm, 1000 sccm, etc.; the flow rate of the N2 is 500-1500 sccm, for example, it can be 500 sccm, 550 sccm, 600 sccm, 650 sccm, 700 sccm, 750 sccm, 800 sccm, 850 sccm, 900 sccm, 950 sccm, 1000 sccm, 1100 sccm, 1200 sccm, 1300 sccm, 1400 sccm, 1500 sccm, etc.; the temperature of the phosphorus diffusion is 800-1000°C, for example, it can be 800°C, 820°C, 840°C, 850°C, 860°C, 880°C, 890°C, 900°C, 920°C, 940°C, 950°C, 960°C, 980°C, 1000°C, etc.; the time of the phosphorus diffusion is 1-3 h, for example, it can be 1 h, 1.2 h, 1.4 h, 1.5 h, 1.6 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.5 h, 2.6 h, 2.8 h, 3 h, etc.; the thickness of the PSG layer is 30-80 nm, for example, it can be 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, etc.; the sheet resistance of the silicon substrate with the phosphorus-doped polysilicon layer is 20-80 Ω, for example, it can be 20 Ω, 25 Ω, 30 Ω, 35 Ω, 40 Ω, 45 Ω, 50 Ω, 55 Ω, 60 Ω, 65 Ω, 70 Ω, 75 Ω, 80 Ω, etc.

[0128] As an optional implementation, in step (3), the second patterning includes: retaining the PSG layer in the N region on the back of the silicon substrate, and removing the PSG layer in the remaining area.

[0129] As an optional implementation, the second patterning is performed by using a picosecond laser.

[0130] As an optional implementation, in step (3), the PSG removing and texturing includes: retaining the N-type doped polysilicon layer and the tunneling oxide layer of the back N region, retaining the P-type doped polysilicon layer and the tunneling oxide layer of the back P region, and texturing the rest of the front and back regions.

[0131] As an optional implementation, in step (3), the passivation treatment includes: depositing an aluminum oxide passivation layer on both sides of the silicon substrate, depositing a silicon nitride passivation layer on the back side, depositing a silicon nitride passivation layer on the front side, and depositing a silicon oxide passivation layer on the front side.

[0132] As an optional implementation, the thickness of the silicon nitride passivation layer is 70-100 nm, for example, it can be 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, etc.

[0133] As an optional implementation, the thickness of the silicon oxide passivation layer is 5-20 nm, for example, it can be 5 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, etc.

[0134] As an optional implementation, as shown in Figure 2 the preparation method of the TBC battery includes the following steps:

[0135] S1, first deposition:

[0136] The tunneling oxide layer and the intrinsic amorphous silicon layer are secondarily deposited on the back of the double-side polished N-type crystalline silicon substrate to obtain a secondarily deposited silicon substrate.

[0137] S2, boron diffusion:

[0138] The back of the silicon substrate obtained in S1 is subjected to boron diffusion to obtain a silicon substrate with a boron-doped polysilicon layer;

[0139] As shown in Figure 3 the silicon substrate with a boron-doped polysilicon layer includes an N-type crystalline silicon substrate 10, and a tunneling oxide layer 20, a P-type doped polysilicon layer 31 and a BSG layer 40 deposited on the back of the N-type crystalline silicon substrate 10 in sequence; it should be noted that the intrinsic amorphous silicon layer of the back S1 will be doped by diffusion to form the P-type doped polysilicon layer 31 at the same time of the boron diffusion.

[0140] S3, first patterning:

[0141] The back part of the BSG layer of the silicon substrate with the BSG layer obtained in step S2 is removed by laser to form a patterned groove, and a silicon substrate with a patterned groove is obtained;

[0142] As shown in Figure 4As shown, the silicon substrate with patterned grooves includes an N-type crystalline silicon substrate 10, and a tunneling oxide layer 20, a P-type doped polysilicon layer 31 and a BSG layer 40 sequentially deposited on the back side of the N-type crystalline silicon substrate 10; and a patterned groove is formed at the BSG layer 40 on the back side of the N-type crystalline silicon substrate 10.

[0143] S4, remove BSG plating and alkali polishing:

[0144] Chain wet removal S3 of the BSG wrap-around plating on the front side of the silicon substrate with the patterned groove, groove polishing to remove the P-type doped polysilicon layer and the tunneling oxide layer in the front wrap-around plating and the patterned groove area on the back side, and the depth of the patterned groove is increased to 2-3 μm to obtain a silicon substrate;

[0145] like Figure 5 As shown, the silicon substrate includes an N-type crystalline silicon substrate 10, and a first tunneling oxide layer 20, a P-type doped polysilicon layer 31 and a BSG layer 40 sequentially deposited on the back side of the N-type crystalline silicon substrate 10, and the depth of the patterned groove increases and extends to the inside of the N-type crystalline silicon substrate 10.

[0146] S5. Secondary deposition:

[0147] A tunneling oxide layer and an intrinsic amorphous silicon layer are deposited twice on the back side of the silicon substrate obtained in step S4 to obtain a twice-deposited silicon substrate.

[0148] S6, Phosphorus Diffusion:

[0149] Phosphorus is diffused on the back side of the secondary deposited silicon substrate obtained in S5 to obtain a silicon substrate having a phosphorus-doped polysilicon layer;

[0150] like Figure 6 As shown, the silicon substrate with a phosphorus-doped polysilicon layer includes an N-type crystalline silicon substrate 10, and a tunneling oxide layer 20, a P-type doped polysilicon layer 31, a BSG layer 40, a tunneling oxide layer 20, an N-type doped polysilicon layer 32 and a PSG layer 41 sequentially deposited on the back side of the N-type crystalline silicon substrate 10; and a second tunneling oxide layer 21, an N-type doped polysilicon layer 32 and a PSG layer 41 are sequentially deposited at the patterned groove; it should be noted that while the phosphorus is diffused, the intrinsic amorphous silicon layer 30 on the back side will form an N-type doped polysilicon layer 32.

[0151] S7, Second Graphicalization

[0152] Retain step S6 to obtain the N-region PSG layer of the silicon substrate having the phosphorus-doped polysilicon layer, remove the PSG layer in the remaining region, and obtain the silicon substrate (such as Figure 7 shown).

[0153] S8, remove PSG plating and texturing:

[0154] S7, removing the N-type doped polysilicon layer and the tunneling oxide layer of the N region on the back surface of the silicon substrate after the second patterning, retaining the P-type doped polysilicon layer and the tunneling oxide layer of the P region on the back surface, and texturing the rest of the front and back surface regions to obtain a textured silicon substrate (as shown in FIG. 8). Figure 8

[0155] S9, passivation treatment and printing electrodes:

[0156] S8, depositing an aluminum oxide passivation layer, a silicon nitride passivation layer and a silicon oxide passivation layer on the front surface of the textured silicon substrate; depositing an aluminum oxide passivation layer and a silicon nitride passivation layer on the back surface of the textured silicon substrate; printing an N region electrode on the N region on the back surface of the passivated silicon substrate and printing a P region electrode on the P region on the back surface of the passivated silicon substrate; sintering and performing light injection to obtain the TBC cell.

[0157] The present application will be further described in the following specific examples and comparative examples, but it should be understood that these examples are only for a more detailed description and should not be understood as limiting the present application in any form.

[0158] Preparation Example 1

[0159] The present preparation example provides a textured cell prepared by the following steps:

[0160] S1, LPCVD1:

[0161] A tunneling oxide layer and an intrinsic amorphous silicon layer are deposited on the back surface of a double-side polished N-type crystalline silicon substrate by an LPCVD method; wherein the thickness of the tunneling oxide layer is 1.8 nm; the temperature for depositing the tunneling oxide layer is 580°C, and the time for depositing the tunneling oxide layer is 50 min; the thickness of the intrinsic amorphous silicon layer is 300 nm; the temperature for depositing the intrinsic amorphous silicon layer is 580°C, and the time for depositing the intrinsic amorphous silicon layer is 75 min.

[0162] S2, boron diffusion:

[0163] The cell treated by S1 is subjected to boron diffusion; wherein a mixture gas of BCl3, O2 and N2 is introduced, the flow rate of BCl3 is 300 sccm, the flow rate of O2 is 850 sccm, the flow rate of N2 is 2750 sccm, the deposition temperature is 900°C, the deposition time is 1.5 h, the thickness of the BSG layer is 50 nm, and the sheet resistance is 150Ω.

[0164] S3, patterning 1:

[0165] ​The battery piece after S2 treatment is sequentially subjected to first patterning; wherein, the step of first patterning is specifically: removing part of the BSG layer (the BSG layer of the subsequent Gap area + N area) on the back of the battery piece after S2 treatment to form a patterned groove; the removal is performed by picosecond laser, the depth of the patterned groove is 55 nm, and the width of the patterned groove is 550 μm.

[0166] S4, BSG removal + alkali polishing:

[0167] The battery piece after S3 treatment is subjected to BSG removal + alkali polishing; wherein, the step of BSG removal + alkali polishing is specifically: chain wet method is used to remove the BSG plating on the front surface, and tank type polishing is used to remove the P-type doped polysilicon layer and the tunneling oxide layer in the area of the patterned groove on the back surface, and the depth of the patterned groove is increased to 2.5 μm.

[0168] S5, LPCVD2:

[0169] LPCVD method is used to deposit on both surfaces of the battery piece after S4 treatment to form a tunneling oxide layer and an intrinsic amorphous silicon layer; wherein, the thickness of the tunneling oxide layer is 1.8 nm; the temperature for depositing the tunneling oxide layer is 580 ℃, and the time for depositing the tunneling oxide layer is 50 min; the thickness of the intrinsic amorphous silicon layer is 300 nm; the temperature for depositing the intrinsic amorphous silicon layer is 580 ℃, and the time for depositing the intrinsic amorphous silicon layer is 75 min.

[0170] S6, phosphorus diffusion:

[0171] The battery piece after S5 treatment is subjected to phosphorus diffusion; wherein, POCl3, O2 and N2 mixed gas is introduced, the flow rate of POCl3 is 1500 sccm, the flow rate of O2 is 800 sccm, the flow rate of N2 is 1000 sccm, the deposition temperature is 900 ℃, the deposition time is 2 h, the thickness of the PSG layer is 50 nm, and the square resistance is 30 Ω.

[0172] S7, patterning 2:

[0173] The N-type doped polysilicon layer and the tunneling oxide layer in the N area on the back of the battery piece after S6 treatment are retained, and the PSG layer in the remaining area is removed; wherein, the removal is performed by picosecond laser.

[0174] S8, PSG removal + texturing:

[0175] The N-type doped polysilicon layer and the tunneling oxide layer in the N area on the back of the battery piece after S7 treatment are retained, and the P-type doped polysilicon layer and the tunneling oxide layer in the P area on the back are retained, the remaining areas on the front and back surfaces are textured, and the textured battery piece is obtained.

[0176] Example 1

[0177] The embodiment provides a battery piece with an aluminum oxide passivation layer, which is prepared through the following steps.

[0178] (1) The battery piece after texturing provided in Preparation Example 1 is placed in an ALD device, and a mixed gas of ClO2, HCl and HCIO is introduced to perform first pretreatment; wherein the flow ratio of ClO2, HCl and HCIO is 1:2:1, the HCl flow is 2 slm, the pretreatment temperature is 350 DEG C, and the time is 2 min;

[0179] (2) The battery piece after the first pretreatment in step (1) is introduced with a mixed gas of H2 and Ar to perform second pretreatment; the flow ratio of H2 and Ar is 1:2, the Ar flow is 4 slm, the pretreatment temperature is 350 DEG C, and the time is 5 min;

[0180] (3) The battery piece after the second pretreatment in step (2) is introduced with N2 to perform purging; the N2 flow is 15.5 slm, the time is 7.5 min, and vacuum is extracted;

[0181] (4) The battery piece after the treatment in step (3) is introduced with a mixed gas of N2, O2 and H2O to perform third pretreatment; wherein the flow ratio of N2, O2 and H2O is 1:3:2, the O2 flow is 0.6 slm, the pretreatment temperature is 350 DEG C, and the time is 3 min;

[0182] (5) The battery piece after the treatment in step (4) is introduced with trimethylaluminum and water vapor alternately to perform cyclic deposition to obtain an aluminum oxide passivation layer; the deposition temperature is 300 DEG C; the cyclic deposition is performed according to the following ① precursor introduction, ② purification, ③ oxidation and ④ purification, the number of repeated cycles is 35, and the thickness of the aluminum oxide passivation layer is 5 nm;

[0183] ① precursor introduction: introducing an Al-containing precursor gas TMA with a flow of 15 slm; ② purification: introducing a purification gas nitrogen to remove unreacted Al-containing precursor gas and / or byproducts, and the flow of the purification gas is 5 slm; ③ oxidation: introducing an oxidant H2O with a flow of 15 slm to react with the surface-adsorbed aluminum source to form aluminum oxide; and ④ purification: introducing a purification gas nitrogen to remove unreacted oxidant and / or byproducts, and the flow of the purification gas is 5 slm.

[0184] Embodiment 2

[0185] The embodiment provides a battery piece with an aluminum oxide passivation layer, which is prepared through the following steps.

[0186] (1) The cell piece after texturing provided by Preparation Example 1 is subjected to first pretreatment by passing a mixed gas of ClO2, HCl and HCIO therethrough; wherein the flow ratio of ClO2, HCl and HCIO is 1:1:1, the flow rate of HCl is 3 slm, the pretreatment temperature is 350°C, and the time is 1 min;

[0187] (2) The cell piece after first pretreatment in step (1) is subjected to second pretreatment by passing a mixed gas of H2 and Ar therethrough; the flow ratio of H2 and Ar is 1:1, the flow rate of Ar is 5 slm, the pretreatment temperature is 350°C, and the time is 3 min;

[0188] (3) The cell piece after second pretreatment in step (2) is subjected to N2 purging; the flow rate of N2 is 13 slm, the time is 18 min, and vacuum is applied;

[0189] (4) The cell piece after treatment in step (3) is subjected to third pretreatment by passing a mixed gas of N2, O2 and H2O therethrough; wherein the flow ratio of N2, O2 and H2O is 1:2:1, the flow rate of O2 is 0.3 slm, the pretreatment temperature is 350°C, and the time is 1 min;

[0190] (5) The cell piece after treatment in step (4) is subjected to cyclic deposition by alternately passing therethrough trimethylaluminum and water vapor to obtain an aluminum oxide passivation layer; the deposition temperature is 300°C; the cyclic deposition is repeated 35 times according to the following: ① precursor introduction, ② purification, ③ oxidation, and ④ purification, to obtain an aluminum oxide passivation layer with a thickness of 5 nm;

[0191] ① precursor introduction: introducing an Al-containing precursor gas TMA at a flow rate of 15 slm; ② purification: introducing a purging gas nitrogen to remove unreacted Al-containing precursor gas and / or byproducts, the flow rate of the purging gas being 5 slm; ③ oxidation: introducing an oxidizing agent H2O at a flow rate of 15 slm to react with the surface-adsorbed aluminum source to form aluminum oxide; and ④ purification: introducing a purging gas nitrogen to remove unreacted oxidizing agent and / or byproducts, the flow rate of the purging gas being 5 slm.

[0192] Example 3

[0193] The present example provides a cell piece with an aluminum oxide passivation layer, which is prepared by the following steps:

[0194] (1) The cell piece after texturing provided by Preparation Example 1 is subjected to first pretreatment by passing a mixed gas of ClO2, HCl and HCIO therethrough; wherein the flow ratio of ClO2, HCl and HCIO is 1:3:1, the flow rate of HCl is 1 slm, the pretreatment temperature is 350°C, and the time is 3 min;

[0195] (2) The battery piece after the first pretreatment of step (1) is passed through a mixed gas of H2 and Ar for the second pretreatment; the flow ratio of H2 and Ar is 1:3, the flow of Ar is 3 slm, the pretreatment temperature is 350°C, and the time is 5 min;

[0196] (3) The battery piece after the second pretreatment of step (2) is passed through N2 for purging; the flow of N2 is 18 slm, the time is 5 min, and vacuum is extracted;

[0197] (4) The battery piece after the treatment of step (3) is passed through a mixed gas of N2, O2 and H2O for the third pretreatment; wherein the flow ratio of N2, O2 and H2O is 1:4:3, the flow of O2 is 1 slm, the pretreatment temperature is 350°C, and the time is 5 min;

[0198] (5) The battery piece after the treatment of step (4) is alternately passed through trimethylaluminum and water vapor for cyclic deposition to obtain an aluminum oxide passivation layer; the deposition temperature is 300°C; the cyclic deposition is repeated 35 times according to the following ① precursor introduction, ② purification, ③ oxidation, and ④ purification to obtain an aluminum oxide passivation layer with a thickness of 5 nm;

[0199] ① precursor introduction: introducing an Al-containing precursor gas TMA with a flow of 15 slm; ② purification: introducing a purification gas nitrogen to remove unreacted Al-containing precursor gas and / or byproducts, the flow of the purification gas being 5 slm; ③ oxidation: introducing an oxidizing agent H2O with a flow of 15 slm to react with the surface-adsorbed aluminum source to form aluminum oxide; and ④ purification: introducing a purification gas nitrogen to remove unreacted oxidizing agent and / or byproducts, the flow of the purification gas being 5 slm.

[0200] Example 4

[0201] This example provides a battery piece with an aluminum oxide passivation layer, which is different from example 1 only in that in step (1), the flow ratio of ClO2, HCl and HClO is 1:1:6, and the flow of HCl is 0.5 slm; the other steps are consistent with example 1.

[0202] Example 5

[0203] This example provides a battery piece with an aluminum oxide passivation layer, which is different from example 1 only in that in step (1), the flow ratio of ClO2, HCl and HClO is 1:6:1, and the flow of HCl is 3 slm; the other steps are consistent with example 1.

[0204] Example 6

[0205] This example provides a battery piece with an aluminum oxide passivation layer, which differs from Example 1 only in that in step (1), the flow ratio of CIO2, HCl and HCIO is 6:1:1, and the flow rate of HCl is 0.5 slm; other steps are consistent with Example 1.

[0206] Example 7

[0207] This example provides a battery piece with an aluminum oxide passivation layer, which differs from Example 1 only in that in step (2), the flow ratio of H2 and Ar is 5:1, and the flow rate of Ar is 1 slm; other steps are consistent with Example 1.

[0208] Example 8

[0209] This example provides a battery piece with an aluminum oxide passivation layer, which differs from Example 1 only in that in step (2), the flow ratio of H2 and Ar is 1:5, and the flow rate of Ar is 5 slm; other steps are consistent with Example 1.

[0210] Example 9

[0211] This example provides a battery piece with an aluminum oxide passivation layer, which differs from Example 1 only in that in step (4), the flow ratio of N2, O2 and H2O is 4:1:1, and the flow rate of O2 is 0.2 slm; other steps are consistent with Example 1.

[0212] Example 10

[0213] This example provides a battery piece with an aluminum oxide passivation layer, which differs from Example 1 only in that in step (4), the flow ratio of N2, O2 and H2O is 1:4:1, and the flow rate of O2 is 2 slm; other steps are consistent with Example 1.

[0214] Example 11

[0215] This example provides a battery piece with an aluminum oxide passivation layer, which differs from Example 1 only in that in step (4), the flow ratio of N2, O2 and H2O is 1:1:4, and the flow rate of O2 is 0.2 slm; other steps are consistent with Example 1.

[0216] Comparative Example 1

[0217] This comparative example provides a battery piece with an aluminum oxide passivation layer, which is prepared by the following steps:

[0218] The cell wafer after texturing provided by Preparation Example 1 was directly transferred to the ALD equipment, and was subjected to cyclic deposition by alternately introducing trimethylaluminum and water vapor to obtain an aluminum oxide passivation layer; the deposition temperature was 300°C; the cyclic process was repeated for 35 times according to the following ① precursor introduction, ② purification, ③ oxidation, ④ purification, to obtain an aluminum oxide passivation layer with a thickness of 5 nm;

[0219] ① precursor introduction: introducing Al-containing precursor gas TMA with a flow rate of 15 slm; ② purification: introducing purifying gas nitrogen to remove unreacted Al-containing precursor gas and / or byproducts, the flow rate of the purifying gas being 5 slm; ③ oxidation: introducing oxidant H2O with a flow rate of 15 slm to react with the surface-adsorbed aluminum source to form aluminum oxide; ④ purification: introducing purifying gas nitrogen to remove unreacted oxidant and / or byproducts, the flow rate of the purifying gas being 5 slm.

[0220] Comparative Example 2

[0221] This comparative example provides a cell wafer with an aluminum oxide passivation layer, which is different from Example 1 only in that only the first pretreatment of step (1) is not performed, but the second pretreatment of step (2) is prolonged to 6 min, and the third pretreatment of step (4) is prolonged to 4 min; the other steps are consistent with Example 1.

[0222] Comparative Example 3

[0223] This comparative example provides a cell wafer with an aluminum oxide passivation layer, which is different from Example 1 only in that only the second pretreatment of step (2) is not performed, but the first pretreatment of step (1) is prolonged to 5 min, and the third pretreatment of step (4) is prolonged to 5 min; the other steps are consistent with Example 1.

[0224] Comparative Example 4

[0225] This comparative example provides a cell wafer with an aluminum oxide passivation layer, which is different from Example 1 only in that only the third pretreatment of step (4) is not performed, but the first pretreatment of step (1) is prolonged to 4 min, and the third pretreatment of step (4) is prolonged to 6 min; the other steps are consistent with Example 1.

[0226] Comparative Example 5

[0227] This comparative example provides a cell wafer with an aluminum oxide passivation layer, which is different from Example 1 only in that in step (1), the mixed gas does not contain ClO2, the flow rate ratio of HCl and HClO is 1:1, and the flow rate of HCl is 2 slm; the other steps are consistent with Example 1.

[0228] Comparative Example 6

[0229] The comparative example provides a battery piece with an aluminum oxide passivation layer, which is different from example 1 only in that in step (1), the mixed gas does not contain HCl, the flow rate ratio of ClO2 and HClO is 1:1, and the flow rate of HClO is 2 slm; other steps are consistent with example 1.

[0230] Comparative example 7

[0231] The comparative example provides a battery piece with an aluminum oxide passivation layer, which is different from example 1 only in that in step (1), the mixed gas does not contain HClO, the flow rate ratio of ClO2 and HCl is 1:1, and the flow rate of HCl is 2 slm; other steps are consistent with example 1.

[0232] Comparative example 8

[0233] The comparative example provides a battery piece with an aluminum oxide passivation layer, which is different from example 1 only in that in step (1), the mixed gas does not contain H2, and the flow rate of Ar is 6 slm; other steps are consistent with example 1.

[0234] Comparative example 9

[0235] The comparative example provides a battery piece with an aluminum oxide passivation layer, which is different from example 1 only in that in step (1), the mixed gas does not contain O2, the flow rate ratio of N2 and H2O is 1:5, and the flow rate of H2O is 1 slm; other steps are consistent with example 1.

[0236] Comparative example 10

[0237] The comparative example provides a battery piece with an aluminum oxide passivation layer, which is different from example 1 only in that in step (1), the mixed gas does not contain H2O, the flow rate ratio of N2 and O2 is 1:5, and the flow rate of O2 is 1 slm; other steps are consistent with example 1.

[0238] Application example 1

[0239] The application example provides a TBC battery, which is prepared by the following steps:

[0240] An 80-nm silicon nitride passivation layer and a 10-nm silicon oxide passivation layer are sequentially deposited on the aluminum oxide passivation layer on the front surface of the battery piece with an aluminum oxide passivation layer obtained in example 1; an 80-nm silicon nitride passivation layer is deposited on the aluminum oxide passivation layer on the back surface of the battery piece with an aluminum oxide passivation layer obtained in example 1; an N-area electrode is printed on the back surface N area of the battery piece after passivation treatment, and a P-area electrode is printed on the back surface P area of the battery piece after passivation treatment, sintering and light injection are performed, and the TBC battery is obtained.

[0241] Application example 2

[0242] The application example provides a TBC battery, which is different from the application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in the embodiment 1 is replaced by the battery piece with the aluminum oxide passivation layer obtained in the embodiment 2, and other steps are completely consistent with the application example 1.

[0243] Application example 3

[0244] The application example provides a TBC battery, which is different from the application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in the embodiment 1 is replaced by the battery piece with the aluminum oxide passivation layer obtained in the embodiment 3, and other steps are completely consistent with the application example 1.

[0245] Application example 4

[0246] The application example provides a TBC battery, which is different from the application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in the embodiment 1 is replaced by the battery piece with the aluminum oxide passivation layer obtained in the embodiment 4, and other steps are completely consistent with the application example 1.

[0247] Application example 5

[0248] The application example provides a TBC battery, which is different from the application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in the embodiment 1 is replaced by the battery piece with the aluminum oxide passivation layer obtained in the embodiment 5, and other steps are completely consistent with the application example 1.

[0249] Application example 6

[0250] The application example provides a TBC battery, which is different from the application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in the embodiment 1 is replaced by the battery piece with the aluminum oxide passivation layer obtained in the embodiment 6, and other steps are completely consistent with the application example 1.

[0251] Application example 7

[0252] The application example provides a TBC battery, which is different from the application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in the embodiment 1 is replaced by the battery piece with the aluminum oxide passivation layer obtained in the embodiment 7, and other steps are completely consistent with the application example 1.

[0253] Application example 8

[0254] The application example provides a TBC battery, which is different from the application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in the embodiment 1 is replaced by the battery piece with the aluminum oxide passivation layer obtained in the embodiment 8, and other steps are completely consistent with the application example 1.

[0255] Application example 9

[0256] The application example provides a TBC battery, which is different from the application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in the embodiment 1 is replaced by the battery piece with the aluminum oxide passivation layer obtained in the embodiment 9, and other steps are completely consistent with the application example 1.

[0257] Application example 10

[0258] The application example provides a TBC battery, which is different from the application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in the embodiment 1 is replaced by the battery piece with the aluminum oxide passivation layer obtained in the embodiment 10, and other steps are completely consistent with the application example 1.

[0259] Application example 11

[0260] The application example provides a TBC battery, which is different from the application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in the embodiment 1 is replaced by the battery piece with the aluminum oxide passivation layer obtained in the embodiment 11, and other steps are completely consistent with the application example 1.

[0261] Comparative application example 1

[0262] The comparative application example provides a TBC battery, which is different from the application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in the embodiment 1 is replaced by the battery piece with the aluminum oxide passivation layer obtained in the comparative example 1, and other steps are completely consistent with the application example 1.

[0263] Comparative application example 2

[0264] The comparative application example provides a TBC battery, which is different from the application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in the embodiment 1 is replaced by the battery piece with the aluminum oxide passivation layer obtained in the comparative example 2, and other steps are completely consistent with the application example 1.

[0265] Comparative application example 3

[0266] The comparative application example provides a TBC battery, which is different from the application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in the embodiment 1 is replaced by the battery piece with the aluminum oxide passivation layer obtained in the comparative example 3, and other steps are completely consistent with the application example 1.

[0267] Comparative application example 4

[0268] The comparative application example provides a TBC battery, which is different from the application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in the embodiment 1 is replaced by the battery piece with the aluminum oxide passivation layer obtained in the comparative example 4, and other steps are completely consistent with the application example 1.

[0269] Comparative application example 5

[0270] This comparative application example provides a TBC battery, which is different from application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in example 1 is replaced with the battery piece with the aluminum oxide passivation layer obtained in comparative example 5, and other steps are completely consistent with application example 1.

[0271] Comparative application example 6

[0272] This comparative application example provides a TBC battery, which is different from application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in example 1 is replaced with the battery piece with the aluminum oxide passivation layer obtained in comparative example 6, and other steps are completely consistent with application example 1.

[0273] Comparative application example 7

[0274] This comparative application example provides a TBC battery, which is different from application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in example 1 is replaced with the battery piece with the aluminum oxide passivation layer obtained in comparative example 7, and other steps are completely consistent with application example 1.

[0275] Comparative application example 8

[0276] This comparative application example provides a TBC battery, which is different from application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in example 1 is replaced with the battery piece with the aluminum oxide passivation layer obtained in comparative example 8, and other steps are completely consistent with application example 1.

[0277] Comparative application example 9

[0278] This comparative application example provides a TBC battery, which is different from application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in example 1 is replaced with the battery piece with the aluminum oxide passivation layer obtained in comparative example 9, and other steps are completely consistent with application example 1.

[0279] Comparative application example 10

[0280] This comparative application example provides a TBC battery, which is different from application example 1 in that the battery piece with the aluminum oxide passivation layer obtained in example 1 is replaced with the battery piece with the aluminum oxide passivation layer obtained in comparative example 10, and other steps are completely consistent with application example 1.

[0281] Test example 1

[0282] Test sample: TBC batteries provided in application examples 1-11 and comparative application examples 1-10;

[0283] Test method: test the electrical performance using a Halm test system.

[0284] The specific test results are shown in Table 1:

[0285] Table 1

[0286]

[0287]

[0288] As shown in Table 1, the pretreatment step in the preparation method of the alumina passivation layer can effectively remove the adsorbed contaminant particles in the oxidation layer on the silicon substrate after texturing, improve the cleanliness of the silicon wafer surface, thereby reducing the oxidation defects caused by the introduction of metal impurities, and effectively removing the irregular natural oxidation layer; the pretreatment step in the preparation method of the alumina passivation layer can introduce a weakly oxidized surface, which is more conducive to the formation of a Si-O-Al structure with low interface defect density, and the low-valence oxidation state surface promotes the formation of an octahedral AlO6 structure, enhances the negative fixed charge density, thereby reducing the recombination current density of the TBC cell, and significantly improving the open-circuit voltage and conversion efficiency.

[0289] As can be seen from the comparison of Application Example 1 and Application Examples 4-6, the quality of the alumina passivation layer according to the present application can be further improved by optimizing the flow ratio of ClO2, HCl and HClO in the first pretreatment, thereby improving the electrical performance of the TBC cell.

[0290] As can be seen from the comparison of Application Example 1 and Application Examples 7-8, the quality of the alumina passivation layer according to the present application can be further improved by optimizing the flow ratio of H2 and Ar in the second pretreatment, thereby improving the electrical performance of the TBC cell.

[0291] As can be seen from the comparison of Application Example 1 and Application Examples 9-11, the quality of the alumina passivation layer according to the present application can be further improved by optimizing the flow ratio of N2, O2 and H2O in the first pretreatment, thereby improving the electrical performance of the TBC cell.

[0292] As can be seen from the comparison of Application Example 1 and Comparative Application Example 1, the alumina passivation layer deposited on the surface of the silicon wafer after texturing by atomic layer deposition (ALD) in Comparative Application Example 1 has poor adhesion to the textured surface due to the uneven natural oxidation layer of the cell wafer after texturing, uneven initial substrate surface, contamination or weakly bonded areas, etc., resulting in a significant reduction in the electrical performance of the TBC cell.

[0293] As can be seen from the comparison of Application Example 1 and Comparative Application Examples 2-4, the three pretreatment steps in the present application are essential, otherwise even if the time of other pretreatment is extended, the surface quality of the silicon substrate after texturing cannot be well improved, and a small amount of contaminant particles may still be adsorbed in the oxidation layer, making the cleanliness of the silicon wafer surface insufficient, or a small amount of metal impurities may still remain, or a small amount of irregular natural oxidation layer may exist on part of the textured surface.

[0294] From the comparison between the application example 1 and the comparative application examples 5-7, it can be seen that the first pretreatment needs to use the mixed gas of chlorine dioxide, hydrogen chloride and hypochlorous acid, and the three gases are indispensable, and the three gases are combined to sufficiently remove the adsorbed contaminant particles in the oxidation layer, so as to improve the cleanliness of the silicon wafer surface, thereby reducing the oxidation defects caused by the introduction of metal impurities.

[0295] From the comparison between the application example 1 and the comparative application example 8, it can be seen that the mixed gas of hydrogen (H2) and argon (Ar) is passed to perform the second pretreatment, otherwise it is difficult to effectively remove the irregular natural oxidation layer.

[0296] From the comparison between the application example 1 and the comparative application examples 9-10, it can be seen that the mixed gas of nitrogen (N2), oxygen (O2) and water vapor (H2O) is passed, which is more conducive to forming the Si-O-Al structure with low interface defect density, and the low-valence oxidation state surface promotes the formation of the octahedral AlO6 structure, enhances the negative fixed charge density, can reduce the composite current density (J) of the TBC battery containing the passivation layer prepared by the method, and improves the open circuit voltage and the conversion efficiency.

[0297] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing an aluminum oxide passivation layer, characterized in that: include: A mixed gas of chlorine dioxide, hydrogen chloride and hypochlorous acid is introduced into the silicon substrate for a first pretreatment; A mixed gas of hydrogen and argon is introduced for a second pretreatment; A mixed gas of nitrogen, oxygen and water vapor is introduced for a third pretreatment; After the pretreatment is completed, an aluminum oxide passivation layer is deposited on the silicon substrate.

2. The method for preparing an aluminum oxide passivation layer according to claim 1, wherein The first pretreatment, the second pretreatment and the third pretreatment are performed using an ALD process; Preferably, in the first pretreatment, the flow ratio of the chlorine dioxide, hydrogen chloride and hypochlorous acid is (0.5-1.5):(1-3):(0.5-1.5); Preferably, in the first pretreatment, the flow rate of the hydrogen chloride is 1 to 3 slm; Preferably, the temperature of the first pretreatment is 300-400° C.; and the time of the first pretreatment is 1-3 minutes.

3. The method for preparing an aluminum oxide passivation layer according to claim 1, wherein: In the second pretreatment, the flow ratio of the hydrogen gas to the argon gas is (0.5-1.5):(1-3); Preferably, in the second pretreatment, the flow rate of the argon gas is 3 to 5 slm; Preferably, the temperature of the second pretreatment is 300-400° C.; and the time of the second pretreatment is 3-8 minutes.

4. The method for preparing an aluminum oxide passivation layer according to claim 1, wherein: Between the second pretreatment and the third pretreatment, the method further comprises: introducing nitrogen to purge and evacuate; Preferably, during the purge, the flow rate of the nitrogen is 13 to 18 slm; Preferably, the purging time is 5 to 18 minutes.

5. The method for preparing an aluminum oxide passivation layer according to claim 1, wherein: In the third pretreatment, the flow ratio of the nitrogen, oxygen and water vapor is (0.5-1.5):(2-4):(1-3); Preferably, in the third pretreatment, the flow rate of the oxygen is 0.3 to 1 slm; Preferably, the temperature of the third pretreatment is 300-400° C.; and the time of the third pretreatment is 1-5 minutes.

6. The method for preparing an aluminum oxide passivation layer according to claim 1, wherein: Depositing the aluminum oxide passivation layer is performed using an ALD process; Preferably, depositing the aluminum oxide passivation layer comprises the following steps: Trimethylaluminum and water vapor are alternately introduced into the pretreated silicon substrate for cyclic deposition to obtain an aluminum oxide passivation layer.

7. An aluminum oxide passivation layer, characterized in that: The aluminum oxide passivation layer is prepared by the preparation method according to any one of claims 1 to 6.

8. A TBC battery, characterized in that: The TBC battery comprises the aluminum oxide passivation layer according to claim 7, or the aluminum oxide passivation layer prepared by the preparation method according to any one of claims 1 to 6.

9. The TBC battery according to claim 8, characterized in that include: N-type crystalline silicon substrate; The back side of the N-type crystalline silicon substrate includes a P region, an N region, and an isolation region between the P region and the N region, wherein the P region and the N region are spaced apart; the P region includes a tunneling oxide layer, a P-type doped polysilicon layer, an aluminum oxide passivation layer, and a silicon nitride passivation layer arranged from the inside out; the N region includes a tunneling oxide layer, an N-type doped polysilicon layer, an aluminum oxide passivation layer, and a silicon nitride passivation layer arranged from the inside out; the P region is provided with a P region electrode, and the N region is provided with an N region electrode; The front surface of the N-type crystalline silicon substrate has a pyramid velvet structure; the front surface of the N-type crystalline silicon substrate includes an aluminum oxide passivation layer, a silicon nitride passivation layer and a silicon oxide passivation layer arranged from the inside to the outside.

10. A method for preparing a TBC battery, characterized in that: include: (1) depositing a tunneling oxide layer and an intrinsic amorphous silicon layer on the back side of an N-type crystalline silicon substrate; (2) performing boron diffusion on the back side of the silicon substrate deposited in step (1) to form a boron-doped polysilicon layer; (3) The silicon substrate diffused by boron in step (2) is subjected to the first patterning, BSG removal, alkali polishing, deposition of a tunneling oxide layer and an intrinsic amorphous silicon layer, phosphorus diffusion, the second patterning, PSG removal, texturing, passivation, electrode printing and light injection in sequence to obtain the TBC battery; The passivation treatment includes: depositing an aluminum oxide passivation layer on both sides of the textured silicon substrate, depositing a silicon nitride passivation layer on the back side, and depositing a silicon nitride passivation layer and a silicon oxide passivation layer on the front side; wherein the double-sided deposition of the aluminum oxide passivation layer is carried out using the preparation method described in any one of claims 1 to 6.

Images