Method for preparing an alumina passivation layer, alumina passivation layer and tbc cell

Abstract

The application 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 cells. 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 a silicon substrate to perform first pretreatment; introducing a mixed gas of hydrogen and argon to perform second pretreatment; introducing a mixed gas of nitrogen, oxygen and water vapor to perform third pretreatment; and depositing the aluminum oxide passivation layer on the silicon substrate after the pretreatment is completed. The preparation method solves the problem that the existing technology directly deposits aluminum oxide on the silicon substrate after texturing, and the poor uniformity of the natural oxidation layer leads to poor adhesion of the aluminum oxide to the textured surface, effectively improves the passivation performance of the prepared aluminum oxide passivation layer, and thus significantly improves the open voltage and conversion efficiency of the TBC battery prepared from the aluminum oxide passivation layer.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a method for preparing an alumina passivation layer, the alumina passivation layer, and a TBC cell. Background Technology

[0002] When texturized TBC silicon wafers are exposed to the environment, they easily form an irregular, impurity-laden natural oxide layer. This is due to several factors: the textured TBC silicon wafer surface has a huge specific surface area and extremely high chemical reactivity (especially in dangling bonds and high curvature regions), causing it to oxidize very rapidly and unevenly when exposed to air containing oxygen, water vapor, and various pollutants. Simultaneously, environmental pollutants are adsorbed and embedded into the growing oxide layer, resulting in a natural oxide layer characterized by uneven thickness, a loose and disordered structure, high levels of defects and impurities, and a rough interface.

[0003] The existing technology uses atomic layer deposition (ALD) on textured silicon wafers to deposit alumina passivation layers. While ALD offers excellent step coverage and conformability (uniformly covering complex morphologies), its film quality is highly dependent on the nucleation conditions of the initial few cycles. Textured solar cells naturally exhibit poor oxide uniformity. If the initial substrate surface is uneven, contaminated, or contains weak bonding regions, subsequent alumina deposition may result in poor adhesion to the textured surface, or the appearance of pyramidal valleys, contaminant edges, or weak / pinhole areas in the oxide layer. This can lead to incomplete coverage, film discontinuities, and even stress concentration at abrupt changes in oxide thickness or contaminant protrusions, causing microcracks or peeling. Consequently, the passivation performance of the passivation layer deteriorates, ultimately leading to a decrease in the on-state voltage and conversion efficiency of the prepared TBC solar cell.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing an alumina passivation layer, an alumina passivation layer, and a TBC battery. The preparation method solves the problem in the prior art where alumina is directly deposited on a silicon substrate after texturing, resulting in poor adhesion between the alumina and the texturing surface due to the poor uniformity of the natural oxide layer. The method effectively improves the passivation performance of the prepared alumina passivation layer, thereby significantly improving the turn-on voltage and conversion efficiency of the TBC battery prepared from it.

[0006] To achieve the above objectives, the following technical solution is proposed:

[0007] In a first aspect, the present invention provides a method for preparing an alumina passivation layer, comprising:

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

[0009] Furthermore, the first, second, and third pretreatments are performed using the ALD process.

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

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

[0012] Furthermore, the temperature of the first pretreatment is 300–400°C.

[0013] Furthermore, the time for the first preprocessing is 1 to 3 minutes.

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

[0015] Furthermore, in the second pretreatment, the flow rate of the argon gas is 3 to 5 slm.

[0016] Furthermore, the temperature of the second pretreatment is 300–400°C.

[0017] Furthermore, the second pretreatment takes 3 to 8 minutes.

[0018] Furthermore, between the second and third pretreatments, the process also includes: purging with nitrogen gas and evacuating the vacuum.

[0019] Furthermore, during the purging, the flow rate of the nitrogen gas is 13–18 slm.

[0020] Furthermore, the purging time is 5 to 18 minutes.

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

[0022] Furthermore, in the third pretreatment, the oxygen flow rate is 0.3 to 1 slm.

[0023] Furthermore, the temperature of the third pretreatment is 300–400°C.

[0024] Furthermore, the time for the third pretreatment is 1 to 5 minutes.

[0025] Furthermore, the deposition of the alumina passivation layer is performed using the ALD process.

[0026] Further, depositing the alumina passivation layer includes the following steps:

[0027] An aluminum-containing precursor gas and an oxidant are alternately introduced into the pretreated silicon substrate for cyclic deposition to obtain an aluminum oxide passivation layer.

[0028] In a second aspect, the present invention provides an alumina passivation layer, which is prepared by the preparation method described in the first aspect.

[0029] Thirdly, the present invention provides a TBC battery, the TBC battery comprising an aluminum oxide passivation layer as described in the second aspect, or an aluminum oxide passivation layer prepared by the preparation method described in the first aspect.

[0030] Furthermore, the TBC battery comprises: an N-type crystalline silicon substrate;

[0031] The back surface of the N-type crystalline silicon substrate includes a P-region, an N-region, and an isolation region located between the P-region and the N-region, with the P-region and the N-region being spaced apart. The P-region includes, from the inside out, a tunneling oxide layer, a P-type doped polycrystalline silicon layer, an aluminum oxide passivation layer, and a silicon nitride passivation layer. The N-region includes, from the inside out, a tunneling oxide layer, an N-type doped polycrystalline silicon layer, an aluminum oxide passivation layer, and a silicon nitride passivation layer. A P-region electrode is disposed in the P-region, and an N-region electrode is disposed in the N-region.

[0032] The front side of the N-type crystalline silicon substrate has a pyramidal textured surface; the front side 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 out.

[0033] Fourthly, the present invention provides a method for preparing a TBC battery, comprising:

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

[0035] (2) Boron diffusion is performed on the back side of the silicon substrate obtained in step (1) to form a boron-doped polycrystalline silicon layer;

[0036] (3) The silicon substrate of boron diffusion in step (2) is subjected to the following steps in sequence: first patterning, BSG removal, alkaline polishing, deposition of tunneling oxide layer and intrinsic amorphous silicon layer, phosphorus diffusion, second patterning, PSG removal, texturing, passivation treatment, electrode printing and light injection to obtain the TBC battery.

[0037] The passivation process includes: depositing an alumina passivation layer on both sides of the texturized 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 alumina passivation layer is deposited on both sides using the preparation method described in the first aspect.

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

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

[0040] (2) The pretreatment step of the alumina passivation layer preparation method of the present invention can introduce a weak oxide surface, which is more conducive to the formation of a Si-O-Al structure with low interface defect density. At the same time, the low-valence oxide surface promotes the formation of octahedral AlO6 structure and enhances the negative fixed charge density, thereby reducing the recombination current density of TBC battery and significantly improving the open circuit voltage and conversion efficiency. Attached Figure Description

[0041] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the TBC battery described in this invention.

[0043] Figure 2 This is a process flow diagram of the TBC battery preparation method described in this invention.

[0044] Figure 3 This is a schematic diagram of the structure of the battery cell obtained by boron diffusion in the preparation method of the TBC battery described in this invention.

[0045] Figure 4 This is a schematic diagram of the structure of the battery cell obtained by the first graphical representation in the preparation method of the TBC battery described in this invention.

[0046] Figure 5 This is a schematic diagram of the structure of the battery cell obtained by BSG winding plating and alkaline polishing in the preparation method of the TBC battery of the present invention.

[0047] Figure 6This is a schematic diagram of the structure of the battery cell obtained by phosphorus diffusion in the preparation method of the TBC battery of the present invention.

[0048] Figure 7 This is a schematic diagram of the structure of the battery cell obtained by the second patterning in the preparation method of the TBC battery of the present invention.

[0049] Figure 8 This is a schematic diagram of the structure of the battery cell obtained by PSG removal and texturing in the preparation method of the TBC battery of the present invention.

[0050] In this diagram, 10 represents the N-type crystalline silicon substrate, 20 represents the tunneling oxide layer, 31 represents the P-type doped polycrystalline silicon layer, 32 represents the N-type doped polycrystalline silicon layer, 40 represents the BSG layer, 41 represents the PSG layer, 60 represents the alumina passivation layer, 61 represents the silicon nitride passivation layer, 62 represents the silicon oxide passivation layer, 71 represents the P-region electrode, and 72 represents the N-region electrode. Detailed Implementation

[0051] Unless otherwise defined herein, scientific and process terms used in conjunction with this invention should have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms should be clear; however, in any case of potential ambiguity, the definitions provided herein take precedence over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0052] It should be noted that specific details are set forth in the following description to provide a full understanding of the invention. However, the invention can be practiced in many ways other than those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0053] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] In a first aspect, the present invention provides a method for preparing an alumina passivation layer, the method comprising:

[0055] A first pretreatment is performed by introducing a mixture of chlorine dioxide, hydrogen chloride, and hypochlorous acid into the silicon substrate; a second pretreatment is performed by introducing a mixture of hydrogen and argon; a third pretreatment is performed by introducing a mixture of nitrogen, oxygen, and water vapor; after the pretreatment is completed, an aluminum oxide passivation layer is deposited on the silicon substrate.

[0056] In this invention, a surface pretreatment is performed before depositing alumina: First, a mixed gas of chlorine dioxide (ClO2), hydrogen chloride (HCl), and hypochlorous acid (HClO) is introduced for the first pretreatment. Chlorine atoms can purify the activity of metal ions such as sodium ions, while hydrogen atoms can passivate dangling bonds on the oxide layer surface. The combined effect of these three gases removes adsorbed contaminant particles from the oxide layer, improving the cleanliness of the silicon wafer surface and reducing oxidation defects caused by the introduction of metal impurities. Next, a mixed gas of hydrogen (H2) and argon (Ar) is introduced for the second pretreatment, effectively removing irregular natural oxide layers. Finally, a mixed gas of nitrogen (N2), oxygen (O2), and water vapor (H2O) is introduced for the third pretreatment, introducing a weakly oxide surface (Si). 2+ / Si 3+ This makes it easier to form a low interface defect density (~1×10⁻⁶). 11 eV -1 cm -2 The Si-O-Al structure, along with the low-valence oxide surface promoting the formation of octahedral AlO6 structure, enhances the negative fixed charge density, which can reduce the composite current density (J) of TBC cells containing the passivation layer prepared by this 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 using the ALD process.

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

[0059] Among them, chlorine dioxide (ClO2): "0.5~1.5" can be, for example, 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, etc.;

[0060] Among them, hydrogen chloride (HCl): "1~3" can be, for example, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, etc.;

[0061] Hypochlorous acid (HClO): "0.5~1.5" can be, for example, 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, etc.

[0062] As an optional implementation, in the first pretreatment, the flow rate of hydrogen chloride (HCl) is 1 to 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 implementation, the temperature of the first pretreatment is 300-400℃, for example, it can be 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, etc.

[0064] As an optional implementation, the time for the first pretreatment is 1 to 3 minutes, for example, it can be 1 minute, 1.2 minutes, 1.4 minutes, 1.6 minutes, 1.8 minutes, 2 minutes, 2.2 minutes, 2.4 minutes, 2.6 minutes, 2.8 minutes, 3 minutes, etc.

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

[0066] Among them, chlorine dioxide (H2): "0.5~1.5" can be, for example, 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, etc.;

[0067] Among them, hydrogen chloride (Ar): "1~3" 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 implementation, in the second pretreatment, the flow rate of argon gas is 3 to 5 slm, for example, 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 implementation, the temperature of the second pretreatment is 300-400℃, for example, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, etc.

[0070] As an optional implementation, the second pretreatment time is 3 to 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 implementation, the process may further include: purging with nitrogen gas and drawing a vacuum (the purpose of which is to remove residual gases and reactants) between the second and third pretreatments.

[0072] As an optional implementation, the flow rate of nitrogen gas during the purging is 13 to 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 implementation, the purging time is 5 to 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] Furthermore, in the third pretreatment, the flow rate ratio of nitrogen, oxygen and water vapor is (0.5-1.5):(2-4):(1-3);

[0075] Nitrogen (N2): "0.5~1.5" can be, for example, 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, etc.

[0076] Among them, oxygen (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, 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 implementation, in the third pretreatment, the oxygen flow rate is 0.3 to 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 implementation, the temperature of the third pretreatment is 300-400℃, for example, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, etc.

[0080] As an optional implementation, the time for the third pretreatment is 1 to 5 minutes, for example, it can be 1 minute, 1.2 minutes, 1.4 minutes, 1.6 minutes, 1.8 minutes, 2 minutes, 2.2 minutes, 2.4 minutes, 2.6 minutes, 2.8 minutes, 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, etc.

[0081] As an optional implementation, the alumina passivation layer is deposited using the ALD process.

[0082] As an optional implementation, depositing the alumina passivation layer includes the following steps:

[0083] Trimethylaluminum and water vapor were alternately introduced into the pretreated silicon substrate for cyclic deposition to obtain an aluminum oxide passivation layer.

[0084] As an optional implementation, the temperature for depositing the alumina passivation layer is 200–400°C, for example, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, etc.

[0085] As an optional implementation, the number of cyclic depositions of the alumina passivation layer is 20 to 50 times, for example, 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 implementation, a single-cycle deposition of the alumina passivation layer includes: a cycle deposition of a surface precursor to the substrate to be deposited, a first purification, oxidation, and a second purification.

[0087] As an optional implementation, the single-cycle deposition of the alumina passivation layer specifically includes:

[0088] ①Precursor introduction: Introduce aluminum-containing precursor gas;

[0089] ② Purification: Introduce purification gas to remove unreacted Al-containing precursor gases and / or byproducts;

[0090] ③Oxidation: Introducing an oxidizing agent;

[0091] ④ Purification: Introduce purification gas to remove unreacted oxidants and / or byproducts.

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

[0093] As an optional implementation, in step ①, the aluminum-containing precursor gas includes trimethylaluminum (TMA).

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

[0095] As an optional implementation, in step ②, the purified gas includes nitrogen.

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

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

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

[0099] As an optional implementation, in step ④, the purified gas includes nitrogen.

[0100] As an optional implementation, the thickness of the alumina passivation layer is 1 to 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 invention provides an alumina passivation layer, which is prepared by the preparation method described in the first aspect.

[0102] Thirdly, the present invention provides a TBC battery, the TBC battery comprising an aluminum oxide passivation layer as described in the second aspect, or an aluminum oxide passivation layer prepared by the preparation method described in the first aspect.

[0103] As an optional implementation method, such as Figure 1 As shown, the TBC battery includes: an N-type crystalline silicon substrate 10; wherein, the back side of the N-type crystalline silicon substrate 10 includes a P-region, an N-region, and an isolation region located between the P-region and the N-region, the P-region and the N-region being alternately arranged; the P-region includes a tunneling oxide layer 20, a P-type doped polycrystalline silicon layer 31, an aluminum oxide passivation layer 60, and a silicon nitride passivation layer 61 arranged from the inside out; the N-region includes a tunneling oxide layer 20, an N-type doped polycrystalline silicon layer 32, an aluminum oxide passivation layer 60, and a silicon nitride passivation layer 61 arranged from the inside out; a P-region electrode 71 is disposed in the P-region, and an N-region electrode 72 is disposed in the N-region; wherein, the front side of the N-type crystalline silicon substrate 10 has a pyramidal textured surface structure; the front side of the N-type crystalline silicon substrate includes an aluminum oxide passivation layer 60, a silicon nitride passivation layer 61, and a silicon oxide passivation layer 62 arranged from the inside out.

[0104] Fourthly, this invention provides a method for preparing a TBC battery, such as... Figure 2 As shown, the preparation method of the TBC battery includes:

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

[0106] (2) Boron diffusion is performed on the back side of the silicon substrate obtained in step (1) to form a boron-doped polycrystalline silicon layer;

[0107] (3) The silicon substrate of boron diffusion in step (2) is subjected to the following steps in sequence: first patterning, BSG removal, alkaline polishing, deposition of tunneling oxide layer and intrinsic amorphous silicon layer, phosphorus diffusion, second patterning, PSG removal, texturing, passivation treatment, electrode printing and light injection to obtain the TBC battery.

[0108] The passivation process includes: depositing an alumina passivation layer on both sides of the texturized 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 alumina passivation layer is deposited on both sides using the preparation method described in the first aspect.

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

[0110] As an optional implementation, in step (1), the thickness of the tunneling oxide layer is 1.0 to 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 to 650 °C, for example, it can be 500 °C, 520 °C, 540 °C, 550 °C, 560 °C, 580 °C, 600 °C, 620 °C, 640 °C, 650 °C, etc.; the time for depositing the tunneling oxide layer is 20 to 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 deposition temperature of the intrinsic amorphous silicon layer is 500-650 °C, for example, it can be 500 °C, 520 °C, 540 °C, 550 °C, 560 °C, 580 °C, 600 °C, 620 °C, 640 °C, 650 °C, etc., and the deposition time of 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 includes: introducing a mixed gas of BCl3, O2 and N2 into the silicon substrate after deposition in step (1) to carry out phosphorus diffusion, thereby obtaining a silicon substrate with a boron-doped polycrystalline silicon layer.

[0113] As an optional implementation, in step (2), the process parameters for boron diffusion include: BCl3 flow rate of 200–400 sccm, for example, 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 of 700–1000 sccm, for example, 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 of 2500–3000 sccm, for example, ... These include 2500 sccm, 2550 sccm, 2600 sccm, 2650 sccm, 2700 sccm, 2750 sccm, 2800 sccm, 2850 sccm, 2900 sccm, 2950 sccm, and 3000 scccmm; the deposition temperature is 800–1000℃, for example, 800℃, 820℃, 840℃, 860℃, 880℃, 900℃, 920℃, and 940℃. Temperatures include 0℃, 960℃, 980℃, and 1000℃; deposition time is 1–2 hours, for example, 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, and 2 hours; sheet resistance is 100–200 Ω, for example, 100 Ω, 110 Ω, 120 Ω, 130 Ω, 140 Ω, 150 Ω, 160 Ω, 170 Ω, 180 Ω, 190 Ω, and 200 Ω.

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

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

[0116] As an optional implementation, the depth of the patterned groove formed in 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 patterned groove formed in the first patterning is 400-600μm, for example, it can be 400μm, 420μm, 440μm, 460μm, 480μm, 500μm, 520μm, 540μm, 560μm, 580μm, 600μm, etc.

[0118] As an optional implementation, step (3) includes: removing the BSG coating and alkaline polishing, which involves: chain-type wet removal of the BSG coating on the front side, and tank-type polishing to remove the P-type doped polysilicon layer and tunneling oxide layer in the patterned groove area on the front side and the back side. 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: depositing the tunneling oxide layer and the intrinsic amorphous silicon layer in a secondary manner by LPCVD.

[0120] As an optional implementation, in step (3), the thickness of the tunneling oxide layer is 1.0 to 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 at which the tunneling oxide layer is deposited is 500 to 650°C, for example, 500°C, 520°C, 540°C, 550°C, 560°C, 580°C, 600°C, 620°C, 640°C, 650°C, etc.

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

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

[0124] As an optional implementation, in step (3), the temperature for depositing the intrinsic amorphous silicon layer is 500 to 650°C, for example, 500°C, 520°C, 540°C, 550°C, 560°C, 580°C, 600°C, 620°C, 640°C, 650°C, etc.

[0125] As an optional implementation, in step (3), the time for depositing the intrinsic amorphous silicon layer is 50 to 100 minutes, for example, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 95 minutes, 100 minutes, etc.

[0126] As an optional implementation, in step (3), the phosphorus diffusion includes: introducing a mixture of POCl3, O2 and N2 gas into the silicon substrate after secondary deposition to carry out phosphorus diffusion, thereby obtaining a silicon substrate with a phosphorus-doped polycrystalline silicon layer.

[0127] As an optional implementation, in step (3), during the phosphorus diffusion process, the flow rate of 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 O2 is 500-1000 sccm, for example, it can be 500 sccm, 550 sccm, 600 sccm, etc. 0 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 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, etc. The phosphorus diffusion temperatures are 800–1000°C, for example, 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 phosphorus diffusion time is 1–3 hours, for example, 1 hour, 1.2 hours, 1.4 hours, 1.5 hours, etc. h, 1.6h, 1.8h, 2h, 2.2h, 2.4h, 2.5h, 2.6h, 2.8h, 3h, etc.; the thickness of the PSG layer is 30-80nm, for example, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, etc.; the sheet resistance of the silicon substrate with the phosphorus-doped polycrystalline silicon layer is 20-80Ω, for example, 20Ω, 25Ω, 30Ω, 35Ω, 40Ω, 45Ω, 50Ω, 55Ω, 60Ω, 65Ω, 70Ω, 75Ω, 80Ω, 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 region.

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

[0130] As an optional implementation, in step (3), the removal of PSG coating and texturing includes: retaining the N-type doped polysilicon layer and tunnel oxide layer in the N region on the back side, retaining the P-type doped polysilicon layer and tunnel oxide layer in the P region on the back side, and texturing the remaining front and back areas.

[0131] As an optional implementation, in step (3), the passivation process includes: depositing an aluminum oxide passivation layer on both sides of the 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.

[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 to 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 method, such as Figure 2 As shown, the preparation method of the TBC battery includes the following steps:

[0135] S1, Primary deposition:

[0136] A secondary deposited silicon substrate is obtained by depositing a tunneling oxide layer and an intrinsic amorphous silicon layer on the back side of a double-polished N-type crystalline silicon substrate.

[0137] S2, boron diffusion:

[0138] Boron diffusion is performed on the back side of the silicon substrate obtained in S1 to obtain a silicon substrate with a boron-doped polycrystalline silicon layer.

[0139] like Figure 3 As shown, the silicon substrate with boron-doped polycrystalline silicon layer includes an N-type crystalline silicon substrate 10, and a tunneling oxide layer 20, a P-type doped polycrystalline silicon layer 31, and a BSG layer 40 sequentially deposited on the back side of the N-type crystalline silicon substrate 10. It should be noted that, during the boron diffusion, the intrinsic amorphous silicon layer on the back side S1 will form a P-type doped polycrystalline silicon layer 31 through diffusion doping.

[0140] S3, First graphical representation:

[0141] The back portion of the BSG layer of the silicon substrate II with the BSG layer obtained in step S2 is removed by laser to form a patterned groove, thereby obtaining a silicon substrate with a patterned groove.

[0142] like 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, BSG coating removal and alkaline polishing:

[0144] Chain-type wet process removes BSG winding plating on the front side of the silicon substrate with patterned grooves in S3, and tank-type polishing removes the P-type doped polysilicon layer and tunneling oxide layer in the patterned groove area on the front side and the back side. The depth of the patterned groove is increased to 2-3 μm to obtain the 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 extends into the interior 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 on the back side of the silicon substrate obtained in step S4 to obtain a secondary deposited silicon substrate.

[0148] S6, Phosphorus diffusion:

[0149] Phosphorus diffusion is performed on the back side of the secondary deposited silicon substrate obtained in S5 to obtain a silicon substrate with a phosphorus-doped polycrystalline silicon layer.

[0150] like Figure 6 As shown, the silicon substrate with phosphorus-doped polysilicon layers 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, during the phosphorus diffusion, an N-type doped polysilicon layer 32 is formed on the intrinsic amorphous silicon layer 30 on the back side.

[0151] S7, Second Graphicalization

[0152] Step S6 yields an N-region PSG layer on a silicon substrate with a phosphorus-doped polycrystalline silicon layer. The remaining PSG layer is then removed to obtain the silicon substrate (e.g., ...). Figure 7 (As shown).

[0153] S8, PSG coating removal and texturing:

[0154] After the second patterning in S7, the N-type doped polysilicon layer and tunneling oxide layer in the N-region of the back side of the silicon substrate are removed, while the P-type doped polysilicon layer and tunneling oxide layer in the P-region of the back side are retained. The remaining front and back areas are then texturized to obtain the texturized silicon substrate (e.g., ...). Figure 8 (As shown).

[0155] S9, passivation treatment, and printed electrodes:

[0156] An aluminum oxide passivation layer, a silicon nitride passivation layer, and a silicon oxide passivation layer are deposited on the front side of the texturized silicon substrate; an aluminum oxide passivation layer and a silicon nitride passivation layer are deposited on the back side of the texturized silicon substrate; an N-region electrode is printed on the N-region of the back side of the passivated silicon substrate, and a P-region electrode is printed on the P-region of the back side of the passivated silicon substrate. The substrate is then sintered and light-injected to obtain the TBC cell.

[0157] The present invention will be further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for the purpose of more detailed illustration and should not be construed as limiting the present invention in any way.

[0158] Preparation Example 1

[0159] This preparation example provides a texturized battery cell, which is prepared by the following steps:

[0160] S1, LPCVD1:

[0161] A tunneling oxide layer and an intrinsic amorphous silicon layer were deposited on the back side of a double-sided polished N-type crystalline silicon substrate using LPCVD. The thickness of the tunneling oxide layer was 1.8 nm, the deposition temperature was 580 °C, and the deposition time was 50 min. The thickness of the intrinsic amorphous silicon layer was 300 nm, the deposition temperature was 580 °C, and the deposition time was 75 min.

[0162] S2, Boron Expansion:

[0163] Boron diffusion was performed on the S1-treated solar cells; a mixed gas of BCl3, O2 and N2 was introduced, with a BCl3 flow rate of 300 sccm, an O2 flow rate of 850 sccm and an N2 flow rate of 2750 sccm, a deposition temperature of 900℃, a deposition time of 1.5 h, a BSG layer thickness of 50 nm, and a sheet resistance of 150 Ω.

[0164] S3, Graphical 1:

[0165] The S2-processed solar cells are sequentially patterned for the first time. Specifically, the first patterning step involves removing a portion of the BSG layer (subsequent Gap region + N region BSG layer) on the back side of the S2-processed solar cell to form a patterned groove. The removal is performed using a picosecond laser, and the depth of the patterned groove is 55 nm, and the width of the patterned groove is 550 μm.

[0166] S4, BSG removal + alkaline polishing:

[0167] The S3-treated solar cells are subjected to BSG removal and alkaline polishing. Specifically, the BSG removal and alkaline polishing steps are: chain wet process to remove the BSG coating on the front side, and tank polishing to remove the P-type doped polycrystalline silicon layer and tunnel oxide layer on the front side coating and the patterned groove area on the back side. The depth of the patterned groove is increased to 2.5 μm.

[0168] S5, LPCVD2:

[0169] A tunneling oxide layer and an intrinsic amorphous silicon layer were formed by double-sided deposition of S4-treated solar cells using LPCVD. The thickness of the tunneling oxide layer was 1.8 nm, the deposition temperature was 580 °C, and the deposition time was 50 min. The thickness of the intrinsic amorphous silicon layer was 300 nm, the deposition temperature was 580 °C, and the deposition time was 75 min.

[0170] S6, Phosphorus diffusion:

[0171] The S5-treated solar cells were subjected to phosphorus diffusion; a mixed gas of POCl3, O2, and N2 was introduced, with a POCl3 flow rate of 1500 sccm, an O2 flow rate of 800 sccm, and an N2 flow rate of 1000 sccm. The deposition temperature was 900℃, the deposition time was 2 h, the PSG layer thickness was 50 nm, and the sheet resistance was 30 Ω.

[0172] S7, Graphical Version 2:

[0173] The PSG layer in the N-region on the back of the battery cell after S6 is retained, and the PSG layer in the remaining region is removed; wherein, the removal is performed using a picosecond laser.

[0174] S8, PSG removal + fleece lining:

[0175] The N-type doped polycrystalline silicon layer and tunneling oxide layer in the N region of the back side of the cell after S7 processing are retained, and the P-type doped polycrystalline silicon layer and tunneling oxide layer in the P region of the back side are retained. The remaining front and back areas are texturized to obtain the texturized cell.

[0176] Example 1

[0177] This embodiment provides a battery cell with an aluminum oxide passivation layer, which is prepared by the following steps:

[0178] (1) The texturized battery cell provided in Preparation Example 1 was placed in an ALD device and a mixture of ClO2, HCl and HClO was introduced for the first pretreatment; wherein the flow rate ratio of ClO2, HCl and HClO was 1:2:1, the flow rate of HCl was 2 slm, the pretreatment temperature was 350℃ and the time was 2 min.

[0179] (2) A mixture of H2 and Ar gas is introduced into the battery cell after the first pretreatment in step (1) for a second pretreatment; the flow ratio of H2 to Ar is 1:2, the flow rate of Ar is 4 slm, the pretreatment temperature is 350℃, and the time is 5 min.

[0180] (3) Purge the battery cells after the second pretreatment in step (2) with N2; the N2 flow rate is 15.5 slm, the time is 7.5 min, and a vacuum is drawn.

[0181] (4) Introduce a mixture of N2, O2 and H2O into the battery cell after step (3) for a third pretreatment; wherein the flow rate ratio of N2, O2 and H2O is 1:3:2, the flow rate of O2 is 0.6slm, the pretreatment temperature is 350℃, and the time is 3min.

[0182] (5) The battery cell treated in 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℃; the following steps are performed: ① precursor introduction, ② purification, ③ oxidation, ④ purification, and the cycle is repeated 35 times to obtain an aluminum oxide passivation layer with a thickness of 5nm.

[0183] ① Precursor introduction: Introduce Al-containing precursor gas TMA at a flow rate of 15 slm; ② Purification: Introduce purification gas nitrogen to remove unreacted Al-containing precursor gas and / or byproducts at a flow rate of 5 slm; ③ Oxidation: Introduce oxidant H2O at a flow rate of 15 slm to react with the aluminum source adsorbed on the surface to form aluminum oxide; ④ Purification: Introduce purification gas nitrogen to remove unreacted oxidant and / or byproducts at a flow rate of 5 slm.

[0184] Example 2

[0185] This embodiment provides a battery cell with an aluminum oxide passivation layer, which is prepared by the following steps:

[0186] (1) A mixture of ClO2, HCl and HClO gas was introduced into the texturized battery cell provided in Preparation Example 1 for the first pretreatment; wherein the flow rate ratio of ClO2, HCl and HClO was 1:1:1, the flow rate of HCl was 3 slm, the pretreatment temperature was 350℃ and the time was 1 min.

[0187] (2) A mixture of H2 and Ar gas is introduced into the battery cell after the first pretreatment in step (1) for a second pretreatment; the flow ratio of H2 to Ar is 1:1, the flow rate of Ar is 5slm, the pretreatment temperature is 350℃, and the time is 3min.

[0188] (3) Purge the battery cells after the second pretreatment in step (2) with N2; the N2 flow rate is 13 slm, the time is 18 min, and a vacuum is drawn.

[0189] (4) A mixture of N2, O2 and H2O is introduced into the battery cell after step (3) for a third pretreatment; wherein the flow rate ratio of N2, O2 and H2O is 1:2:1, the flow rate of O2 is 0.3slm, the pretreatment temperature is 350℃, and the time is 1min.

[0190] (5) The battery cell treated in 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℃; the following steps are performed: ① precursor introduction, ② purification, ③ oxidation, ④ purification, and the cycle is repeated 35 times to obtain an aluminum oxide passivation layer with a thickness of 5nm.

[0191] ① Precursor introduction: Introduce Al-containing precursor gas TMA at a flow rate of 15 slm; ② Purification: Introduce purification gas nitrogen to remove unreacted Al-containing precursor gas and / or byproducts at a flow rate of 5 slm; ③ Oxidation: Introduce oxidant H2O at a flow rate of 15 slm to react with the aluminum source adsorbed on the surface to form aluminum oxide; ④ Purification: Introduce purification gas nitrogen to remove unreacted oxidant and / or byproducts at a flow rate of 5 slm.

[0192] Example 3

[0193] This embodiment provides a battery cell with an aluminum oxide passivation layer, which is prepared by the following steps:

[0194] (1) A mixture of ClO2, HCl and HClO gas was introduced into the texturized battery cell provided in Preparation Example 1 for the first pretreatment; wherein the flow rate ratio of ClO2, HCl and HClO was 1:3:1, the flow rate of HCl was 1 slm, the pretreatment temperature was 350℃ and the time was 3 min.

[0195] (2) A mixture of H2 and Ar gas is introduced into the battery cell after the first pretreatment in step (1) for a second pretreatment; the flow ratio of H2 to Ar is 1:3, the flow rate of Ar is 3slm, the pretreatment temperature is 350℃, and the time is 5min.

[0196] (3) Purge the battery cells after the second pretreatment in step (2) with N2; the N2 flow rate is 18 slm, the time is 5 min, and a vacuum is drawn.

[0197] (4) Introduce a mixture of N2, O2 and H2O into the battery cell after step (3) for a third pretreatment; wherein the flow rate ratio of N2, O2 and H2O is 1:4:3, the flow rate of O2 is 1 slm, the pretreatment temperature is 350℃, and the time is 5 min.

[0198] (5) The battery cell treated in 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℃; the following steps are performed: ① precursor introduction, ② purification, ③ oxidation, ④ purification, and the cycle is repeated 35 times to obtain an aluminum oxide passivation layer with a thickness of 5nm.

[0199] ① Precursor introduction: Introduce Al-containing precursor gas TMA at a flow rate of 15 slm; ② Purification: Introduce purification gas nitrogen to remove unreacted Al-containing precursor gas and / or byproducts at a flow rate of 5 slm; ③ Oxidation: Introduce oxidant H2O at a flow rate of 15 slm to react with the aluminum source adsorbed on the surface to form aluminum oxide; ④ Purification: Introduce purification gas nitrogen to remove unreacted oxidant and / or byproducts at a flow rate of 5 slm.

[0200] Example 4

[0201] This embodiment provides a battery cell with an aluminum oxide passivation layer. The only difference from Embodiment 1 is that in step (1), the flow rate ratio of ClO2, HCl and HClO is 1:1:6 and the flow rate of HCl is 0.5 slm; the other steps are the same as in Embodiment 1.

[0202] Example 5

[0203] This embodiment provides a battery cell with an aluminum oxide passivation layer. The only difference from Embodiment 1 is that in step (1), the flow ratio of ClO2, HCl and HClO is 1:6:1 and the flow rate of HCl is 3slm; the other steps are the same as in Embodiment 1.

[0204] Example 6

[0205] This embodiment provides a battery cell with an aluminum oxide passivation layer. The only difference from Embodiment 1 is that in step (1), the flow rate ratio of ClO2, HCl and HClO is 6:1:1 and the flow rate of HCl is 0.5 slm; the other steps are the same as in Embodiment 1.

[0206] Example 7

[0207] This embodiment provides a battery cell with an aluminum oxide passivation layer. The only difference from Embodiment 1 is that in step (2), the flow ratio of H2 to Ar is 5:1 and the Ar flow rate is 1 slm; the other steps are the same as in Embodiment 1.

[0208] Example 8

[0209] This embodiment provides a battery cell with an aluminum oxide passivation layer. The only difference from Embodiment 1 is that in step (2), the flow ratio of H2 to Ar is 1:5 and the Ar flow rate is 5 slm; the other steps are the same as in Embodiment 1.

[0210] Example 9

[0211] This embodiment provides a battery cell with an aluminum oxide passivation layer. The only difference from Embodiment 1 is that in step (4), the flow rate ratio of N2, O2 and H2O is 4:1:1 and the flow rate of O2 is 0.2 slm; the other steps are the same as in Embodiment 1.

[0212] Example 10

[0213] This embodiment provides a battery cell with an aluminum oxide passivation layer. The only difference from Embodiment 1 is that in step (4), the flow ratio of N2, O2 and H2O is 1:4:1 and the flow rate of O2 is 2slm; the other steps are the same as in Embodiment 1.

[0214] Example 11

[0215] This embodiment provides a battery cell with an aluminum oxide passivation layer. The only difference from Embodiment 1 is that in step (4), the flow rate ratio of N2, O2 and H2O is 1:1:4 and the flow rate of O2 is 0.2 slm; the other steps are the same as in Embodiment 1.

[0216] Comparative Example 1

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

[0218] The texturized battery cell provided in Preparation Example 1 was directly transferred to the ALD equipment, and trimethylaluminum and water vapor were alternately introduced for cyclic deposition to obtain an aluminum oxide passivation layer; the deposition temperature was 300°C; the following process was repeated ① precursor introduction, ② purification, ③ oxidation, and ④ purification, and the number of cycles was 35 times to obtain an aluminum oxide passivation layer with a thickness of 5 nm.

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

[0220] Comparative Example 2

[0221] This comparative example provides a battery cell with an aluminum oxide passivation layer. The only difference from Example 1 is that the first pretreatment in step (1) is omitted, but the time for the second pretreatment in step (2) is extended to 6 minutes, and the time for the third pretreatment in step (4) is extended to 4 minutes; the other steps are the same as in Example 1.

[0222] Comparative Example 3

[0223] This comparative example provides a battery cell with an aluminum oxide passivation layer. The only difference from Example 1 is that the second pretreatment in step (2) is not performed, but the time for the first pretreatment in step (1) is extended to 5 minutes, and the time for the third pretreatment in step (4) is extended to 5 minutes; the other steps are the same as in Example 1.

[0224] Comparative Example 4

[0225] This comparative example provides a battery cell with an aluminum oxide passivation layer. The only difference from Example 1 is that the third pretreatment in step (4) is not performed, but the time for the first pretreatment in step (1) is extended to 4 minutes, and the time for the third pretreatment in step (4) is extended to 6 minutes; the other steps are the same as in Example 1.

[0226] Comparative Example 5

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

[0228] Comparative Example 6

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

[0230] Comparative Example 7

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

[0232] Comparative Example 8

[0233] This comparative example provides a battery cell with an aluminum oxide passivation layer. The only difference from Example 1 is that in step (1) and step (2), the mixed gas does not contain H2 and the Ar flow rate is 6 slm; the other steps are the same as in Example 1.

[0234] Comparative Example 9

[0235] This comparative example provides a battery cell with an aluminum oxide passivation layer. The only difference from Example 1 is that in step (1) and step (4), the mixed gas does not contain O2, the flow ratio of N2 and H2O is 1:5, and the H2O flow rate is 1 slm; the other steps are the same as in Example 1.

[0236] Comparative Example 10

[0237] This comparative example provides a battery cell with an aluminum oxide passivation layer. The only difference from Example 1 is that in step (1) and step (4), the mixed gas does not contain H2O, the flow ratio of N2 and O2 is 1:5, and the flow rate of O2 is 1 slm; the other steps are the same as in Example 1.

[0238] Application Example 1

[0239] This 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 front side of the solar cell with an aluminum oxide passivation layer obtained in Example 1; an 80 nm silicon nitride passivation layer is deposited on the back side of the solar cell with an aluminum oxide passivation layer obtained in Example 1; an N-region electrode is printed on the N-region of the back side of the passivated solar cell, and a P-region electrode is printed on the P-region of the back side of the passivated solar cell. The cells are then sintered and light-injected to obtain the TBC solar cell.

[0241] Application Example 2

[0242] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Example 2. The other steps are completely the same as in Application Example 1.

[0243] Application Example 3

[0244] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Example 3. The other steps are completely the same as in Application Example 1.

[0245] Application Example 4

[0246] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Example 4. The other steps are completely the same as in Application Example 1.

[0247] Application Example 5

[0248] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Example 5. The other steps are completely the same as in Application Example 1.

[0249] Application Example 6

[0250] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Example 6. The other steps are completely consistent with Application Example 1.

[0251] Application Example 7

[0252] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Example 7. The other steps are completely the same as in Application Example 1.

[0253] Application Example 8

[0254] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Example 8. The other steps are completely the same as in Application Example 1.

[0255] Application Example 9

[0256] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Example 9. The other steps are completely the same as in Application Example 1.

[0257] Application Example 10

[0258] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Example 10. The other steps are completely the same as in Application Example 1.

[0259] Application Example 11

[0260] This application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Example 11. The other steps are completely the same as in Application Example 1.

[0261] Comparative Application Example 1

[0262] This comparative application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Comparative Example 1. The other steps are completely consistent with Application Example 1.

[0263] Comparative Application Example 2

[0264] This comparative application example provides a TBC battery. The difference from Application Example 1 is that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Comparative Example 2. The other steps are completely the same as in Application Example 1.

[0265] Comparative Application Example 3

[0266] This comparative application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Comparative Example 3. The other steps are completely consistent with Application Example 1.

[0267] Comparative Application Example 4

[0268] This comparative application example provides a TBC battery. The difference from Application Example 1 is that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Comparative Example 4. The other steps are completely the same as in Application Example 1.

[0269] Comparative Application Example 5

[0270] This comparative application example provides a TBC battery. The difference from Application Example 1 is that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Comparative Example 5. The other steps are completely the same as in Application Example 1.

[0271] Comparative Application Example 6

[0272] This comparative application example provides a TBC battery. The difference from Application Example 1 is that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Comparative Example 6. The other steps are completely the same as in Application Example 1.

[0273] Comparative Application Example 7

[0274] This comparative application example provides a TBC battery. The difference from Application Example 1 is that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Comparative Example 7. The other steps are completely the same as in Application Example 1.

[0275] Comparative Application Example 8

[0276] This comparative application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Comparative Example 8. The other steps are completely consistent with Application Example 1.

[0277] Comparative Application Example 9

[0278] This comparative application example provides a TBC battery. The difference from Application Example 1 is that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Comparative Example 9. The other steps are completely the same as in Application Example 1.

[0279] Comparative Application Example 10

[0280] This comparative application example provides a TBC battery, which differs from Application Example 1 in that the battery cell with an aluminum oxide passivation layer obtained in Example 1 is replaced with the battery cell with an aluminum oxide passivation layer obtained in Comparative Example 10. The other steps are completely consistent with Application Example 1.

[0281] Test Example 1

[0282] Test samples: TBC batteries provided in Application Examples 1-11 and TBC batteries provided in Comparative Application Examples 1-10;

[0283] Test method: Electrical performance was tested using the 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 of the present invention can effectively remove contaminant particles adsorbed in the oxide layer on the silicon substrate after texturing, thereby improving the surface cleanliness of the silicon wafer, reducing oxidation defects caused by the introduction of metal impurities, and effectively removing irregular natural oxide layers. The pretreatment step in the preparation method of the alumina passivation layer of the present invention can introduce a weak oxide surface, which is more conducive to the formation of a Si-O-Al structure with low interface defect density. At the same time, the low-valence oxide state surface promotes the formation of octahedral AlO6 structure, enhances the negative fixed charge density, thereby reducing the recombination current density of TBC cells and significantly improving the open-circuit voltage and conversion efficiency.

[0289] The comparison between Application Example 1 and Application Examples 4-6 shows that the quality of the alumina passivation layer described in this invention 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 battery.

[0290] The comparison between Application Example 1 and Application Examples 7-8 shows that the quality of the alumina passivation layer described in this invention 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 battery.

[0291] The comparison between Application Example 1 and Application Examples 9-11 shows that the quality of the alumina passivation layer described in this invention 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 battery.

[0292] The comparison between Application Example 1 and Comparative Application Example 1 shows that the atomic layer deposition (ALD) method used in Comparative Application Example 1 to deposit an aluminum oxide passivation layer on the surface of the texturized silicon wafer results in poor adhesion between the aluminum oxide and the texturized surface during deposition. This is because the natural oxide layer of the texturized cell has poor uniformity, and the initial substrate surface is uneven, contaminated, or has weak bonding regions. Consequently, the electrical performance of the TBC cell is significantly reduced.

[0293] As can be seen from the comparison between Application Example 1 and Comparative Application Examples 2-4, the three pretreatment steps in this invention are indispensable. Otherwise, even if the time of other pretreatments is extended, the surface quality of the silicon substrate after texturing cannot be improved well. It is expected that a small amount of contaminant particles will still be adsorbed in its oxide layer, resulting in insufficient cleanliness of the silicon wafer surface, or a small amount of metal impurities, or a small amount of irregular natural oxide layer in some textured surfaces.

[0294] The comparison between Application Example 1 and Comparative Application Examples 5-7 shows that the first pretreatment requires a mixture of chlorine dioxide, hydrogen chloride, and hypochlorous acid. All three gases are indispensable. Only by combining the three gases can the adsorbed contaminant particles in the oxide layer be fully removed, thereby improving the cleanliness of the silicon wafer surface and reducing oxidation defects caused by the introduction of metal impurities.

[0295] The comparison between Application Example 1 and Comparative Application Example 8 shows that a second pretreatment using a mixture of hydrogen (H2) and argon (Ar) is necessary to effectively remove the irregular natural oxide layer.

[0296] The comparison between Application Example 1 and Comparative Application Examples 9-10 shows that introducing a mixed gas of nitrogen (N2), oxygen (O2), and water vapor (H2O) is more conducive to the formation of a Si-O-Al structure with low interface defect density. At the same time, the low-valence oxide surface promotes the formation of octahedral AlO6 structure, enhances the negative fixed charge density, reduces the recombination current density (J) of TBC cells containing the passivation layer prepared by this method, and increases the open-circuit voltage and conversion efficiency.

[0297] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an alumina passivation layer, characterized in that, include: A mixture of chlorine dioxide, hydrogen chloride, and hypochlorous acid is introduced into the texturized silicon substrate for the first pretreatment. A second pretreatment is performed by introducing a mixture of hydrogen and argon gas; a third pretreatment is performed by introducing a mixture of nitrogen, oxygen, and water vapor, which introduces weakly oxidized Si onto the surface. 2+ / Si 3+ This facilitates the formation of a Si-O-Al structure with low interface defect density, while the low-valence oxide state surface promotes the formation of octahedral AlO6 structure; after pretreatment, an aluminum oxide passivation layer is deposited on the silicon substrate. In the first pretreatment, the flow rate ratio of chlorine dioxide, hydrogen chloride, and hypochlorous acid is (0.5~1.5):(1~3):(0.5~1.5); In the second pretreatment, the flow rate ratio of hydrogen to argon is (0.5~1.5):(1~3); In the third pretreatment, the flow rate ratio of nitrogen, oxygen and water vapor is (0.5~1.5):(2~4):(1~3); The temperature for the first pretreatment, the second pretreatment, and the third pretreatment is 300~400℃; The first, second, and third pretreatments were performed using the ALD process.

2. The method for preparing the alumina passivation layer according to claim 1, characterized in that, In the first pretreatment, the flow rate of hydrogen chloride is 1~3 slm.

3. The method for preparing the alumina passivation layer according to claim 1, characterized in that, The first preprocessing time is 1 to 3 minutes.

4. The method for preparing the alumina passivation layer according to claim 1, characterized in that, In the second pretreatment, the flow rate of argon gas is 3-5 slm.

5. The method for preparing the alumina passivation layer according to claim 1, characterized in that, The second preprocessing time is 3-8 minutes.

6. The method for preparing the alumina passivation layer according to claim 1, characterized in that, Between the second and third pretreatments, the process also includes: purging with nitrogen gas and evacuating the vacuum.

7. The method for preparing the alumina passivation layer according to claim 6, characterized in that, During the purging, the flow rate of nitrogen is 13-18 slm.

8. The method for preparing the alumina passivation layer according to claim 6, characterized in that, The purging time is 5 to 18 minutes.

9. The method for preparing the alumina passivation layer according to claim 1, characterized in that, In the third pretreatment, the oxygen flow rate is 0.3~1 slm.

10. The method for preparing the alumina passivation layer according to claim 1, characterized in that, The third preprocessing time is 1-5 minutes.

11. The method for preparing the alumina passivation layer according to claim 1, characterized in that, The alumina passivation layer was deposited using the ALD process.

12. The method for preparing the alumina passivation layer according to claim 1, characterized in that, Depositing the alumina passivation layer includes the following steps: Trimethylaluminum and water vapor were alternately introduced into the pretreated silicon substrate for cyclic deposition to obtain an aluminum oxide passivation layer.

13. An alumina passivation layer, characterized in that, The alumina passivation layer is prepared by the preparation method according to any one of claims 1 to 12.

14. A TBC battery, characterized in that, The TBC battery includes the aluminum oxide passivation layer as described in claim 13, or the aluminum oxide passivation layer prepared by any one of the preparation methods described in claims 1 to 12.

15. The TBC battery according to claim 14, characterized in that, include: N-type crystalline silicon substrate; The back surface of the N-type crystalline silicon substrate includes a P-region, an N-region, and an isolation region located between the P-region and the N-region, with the P-region and the N-region being spaced apart. The P-region includes, from the inside out, a tunneling oxide layer, a P-type doped polycrystalline silicon layer, an aluminum oxide passivation layer, and a silicon nitride passivation layer. The N-region includes, from the inside out, a tunneling oxide layer, an N-type doped polycrystalline silicon layer, an aluminum oxide passivation layer, and a silicon nitride passivation layer. A P-region electrode is disposed in the P-region, and an N-region electrode is disposed in the N-region. The front side of the N-type crystalline silicon substrate has a pyramidal textured surface; the front side 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 out.

16. A method for preparing a TBC battery, characterized in that, include: (1) Deposit a tunneling oxide layer and an intrinsic amorphous silicon layer on the back side of an N-type crystalline silicon substrate; (2) Boron diffusion is performed on the back side of the silicon substrate obtained in step (1) to form a boron-doped polycrystalline silicon layer; (3) The silicon substrate of boron diffusion in step (2) is subjected to the following steps in sequence: first patterning, BSG removal, alkaline polishing, deposition of tunneling oxide layer and intrinsic amorphous silicon layer, phosphorus diffusion, second patterning, PSG removal, texturing, passivation treatment, electrode printing and light injection to obtain the TBC battery. The passivation treatment includes: depositing an alumina passivation layer on both sides of the texturized 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 alumina passivation layer is deposited on both sides using the preparation method described in any one of claims 1 to 12.

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