An Al2O3 / SiO2 passivation device for photovoltaic solar cells and its deposition method and application

Abstract

The present application relates to the technical field of battery passivation, and specifically to an Al2O3 / SiO2 passivation device for photovoltaic solar cells, and a deposition method and application thereof. The deposition method comprises: a first SiO2 deposition: using plasma enhanced atomic layer deposition technology (PEALD) to heat and ionize the silicon wafer substrate in a laughing gas environment, and depositing a first SiO2 layer; a first Al2O3 deposition: heating the silicon wafer substrate in a laughing gas and trimethylaluminum environment, and depositing a first Al2O3 layer. The passivation device obtained by this method has a higher battery efficiency, which is specifically manifested in that it has a longer minority carrier lifetime.

Description

Technical Field

[0001] The present application relates to the technical field of battery passivation, and specifically to an Al2O3-based photovoltaic solar cell. 2 O 3 / SiO 2 Passivation device and its deposition method and application. Background Art

[0002] At present, my country's development goals of "carbon peak" and "carbon neutrality" are very clear. From the perspective of global new energy forms, photovoltaic power generation is the focus of new energy development. The speed at which traditional energy is replaced by new energy will only get faster and faster. my country will continue to improve the development layout of wind power and solar power generation, and while continuing to promote the construction of centralized bases, it will fully support the development of distributed wind power and photovoltaics.

[0003] Solar power generation technology refers to the power generation method of converting solar radiation energy into electrical energy through water or other media and devices. At present, solar power generation has two forms: photovoltaic and solar thermal power generation. Photovoltaic, which is the abbreviation of solar photovoltaic power generation system, is a new type of power generation system that uses the photovoltaic effect of solar cell semiconductor materials to directly convert solar radiation energy into electrical energy. The best way to use solar energy is photovoltaic conversion, which is to use the photovoltaic effect to make sunlight hit silicon materials to generate current and directly generate electricity. The photoelectric conversion industry chain formed by the application and development of silicon materials is called "photovoltaic industry", including the production of high-purity polycrystalline silicon raw materials, solar cell production, solar cell module production, and the manufacture of related production equipment. Excellent interface passivation materials, especially in metal oxide semiconductor field effect transistors (MOSFETs), are the key to improving the efficiency of solar cells. They are multilayer structures composed of two or three different dielectric layers, which can provide the possibility of increasing the flat band voltage by simply changing the number of double or triple layers. The origin of this flat band voltage displacement is the dipole, which is only formed at the specific interface of this multilayer material with only one polarity, for example, Al 2 O 3 / SiO 2 It has been reported that the dipole is only in Al with one polarity 2 O 3 / SiO 2 The surface passivation can be enhanced by forming a

[0004] The existing technology generally adopts a single-layer aluminum oxide structure for interface passivation. The current mainstream technologies such as passivation of the rear surface and emitter (PERC) and passivation of the contact (TOPCon) use Al 2 O 3The layer is used as a passivation dielectric layer on the light-receiving surface of the cell, which has a certain chemical / field passivation effect. However, the highest efficiency of the passivated contact TOPCon cell in the existing technology is 26.7%, which is far from the limit efficiency of crystalline silicon of 29.4%.

[0005] SiO 2 The layer is a passivation material known to reduce the recombination of the battery surface. It is generally produced by thermal oxidation at 900 ° C to generate high-quality SiO 2 To form Al 2 O 3 / SiO 2 The stacking must go through ALD (atomic deposition technology), which greatly increases the difficulty of passivation layer deposition and makes it difficult to operate.

[0006] Therefore, it is necessary to provide a solar cell interface passivation method to solve some of the above problems. Summary of the invention

[0007] The present application provides an Al 2 O 3 / SiO 2 The passivation device and its deposition method and application can be used in the field of solar photovoltaic power generation. The passivation method uses PEALD technology, which greatly reduces the difficulty of passivation layer deposition and has strong operability. In addition, the nitrous oxide used for deposition can be conventional industrial gas to meet the demand, and the cost is greatly reduced. The deposition method is more efficient. The SiO in the passivation device obtained by the deposition method is 2 The layer has a higher hydrogen content, which is beneficial to the enhancement of the passivation effect. For example, the conversion efficiency (Eta) of the passivated device is higher and the minority carrier lifetime is longer.

[0008] This application involves the following:

[0009] 1. An Al for photovoltaic solar cells 2 O 3 / SiO 2 Deposition methods for passivating devices,

[0010] The deposition method comprises:

[0011] The first SiO 2 Deposition: Plasma enhanced atomic layer deposition (PEALD) is used to heat and ionize the silicon wafer substrate in a laughing gas environment to deposit the first SiO 2 layer; the first SiO 2 During deposition, the amount of laughing gas introduced is 5000-20000sccm;

[0012] First time Al 2 O 3Deposition: The silicon wafer substrate is heated in a laughing gas and trimethylaluminum environment to deposit the first Al 2 O 3 layer; the first Al 2 O 3 During deposition, the volume ratio of the amount of the laughing gas to the amount of the trimethylaluminum is (6-40):(1-4), preferably (6-15):(1-2).

[0013] 2. According to the deposition method of item 1, the first SiO 2 During deposition, the amount of laughing gas introduced is 8000-18000sccm;

[0014] And / or, the heating temperature is 200-500°C.

[0015] 3. The deposition method according to any one of items 1 to 3, wherein the first Al 2 O 3 During deposition, the amount of laughing gas introduced is 300-2000sccm; preferably 500-1200sccm;

[0016] And / or, the heating temperature is 200-500°C;

[0017] And / or, the amount of trimethylaluminum introduced is 50-200 sccm; preferably 80-150 sccm.

[0018] 4. The deposition method according to any one of items 1 to 3, further comprising:

[0019] Second SiO 2 Deposition: Make Al 2 O 3 Deposition and SiO 2 The deposited silicon wafer substrate is heated in an environment of laughing gas and silane to obtain a deposited second SiO 2 layer;

[0020] Preferably, the second SiO 2 During deposition, the volume ratio of the amount of the laughing gas to the amount of the silane is (40-140):(7-33), more preferably (50-90):(10-23).

[0021] 5. According to the deposition method of item 4, the second SiO 2 During deposition, the amount of laughing gas introduced is 4000-14000sccm, preferably 5000-9000sccm;

[0022] And / or, the amount of silane introduced is 700-3300 sccm, preferably 1000-2300 sccm;

[0023] And / or, the heating temperature is 200-500°C.

[0024] 6. The deposition method according to item 4 or 5, further comprising:

[0025] Repeat the second SiO 2 Deposition steps to obtain deposition on different Al 2 O 3 SiO 2 layer;

[0026] Repeat the first Al 2 O 3 Deposition steps to obtain deposition on different SiO 2 Al on the layer 2 O 3 layer;

[0027] Preferably, the repetition number is 0-4 times; more preferably 1-3 times.

[0028] 7. The deposition method according to any one of items 1 to 6, wherein the first SiO 2 The ionization conditions during deposition include: radio frequency power of 6000-15000w, and duty cycle of 50:100ms.

[0029] 8. The deposition method according to any one of items 1 to 7, wherein the silicon wafer substrate is selected from any one or more of a single crystal silicon wafer substrate, a polycrystalline silicon wafer substrate, and a solar cell to be passivated;

[0030] Preferably, the silicon wafer substrate is a single crystal P-type silicon wafer and / or a single crystal N-type silicon wafer.

[0031] 9. According to the deposition method described in Item 8, the layer structure of the single crystal P-type silicon wafer includes: an original single crystal P-type silicon wafer, a first velvet layer and a polishing layer arranged on both sides of the original single crystal P-type silicon wafer, a tunneling oxide layer and a p-type polysilicon layer arranged outside the polishing layer on either side, a second velvet layer and a PN junction layer arranged outside the polishing layer where the tunneling oxide layer is not arranged, and mask layers arranged on both sides.

[0032] 10. According to the deposition method of item 9, the preparation method of the first velvet layer comprises: placing the single crystal P-type silicon wafer in an alkaline solution; preferably, the alkali in the alkaline solution is sodium hydroxide;

[0033] and / or, the tunneling oxide layer is obtained by LPCVD deposition; preferably, the thickness of the tunneling oxide layer is 1.5-2.0 nm;

[0034] and / or, the p-type polysilicon layer is obtained by a method comprising high temperature boron diffusion;

[0035] And / or, the PN junction layer is obtained by a method involving high temperature phosphorus diffusion.

[0036] 11. The deposition method according to any one of items 1 to 10, wherein the SiO 2 The thickness of the layer is 2-4 nm;

[0037] and / or, wherein Al 2 O 3 The thickness of the layer is 2-5 nm.

[0038] 12. An Al for photovoltaic solar cells 2 O 3 / SiO 2 A passivation device is obtained by using the deposition method described in any one of items 1-11.

[0039] 13. The Al according to claim 12 2 O 3 / SiO 2 The passivation device comprises a silicon wafer substrate and (Al 2 O 3 / SiO 2 )n laminated film;

[0040] Preferably, n is a natural number selected from 1 to 5;

[0041] More preferably, n is a natural number selected from 1-3;

[0042] More preferably, the n is 3.

[0043] 14. A photovoltaic solar cell, comprising the Al according to claim 12 or 13 2 O 3 / SiO 2 Passivated device.

[0044] 15. The photovoltaic solar cell according to item 14, further comprising a 2 O 3 / SiO 2 Anti-reflection film layer and metal grid line outside the passivation device;

[0045] Preferably, the anti-reflection film layer is a silicon nitride anti-reflection film layer;

[0046] Preferably, the anti-reflection film layer has a thickness of 60-100 nm.

[0047] Effects of the Invention

[0048] The present application first utilizes PEALD technology when preparing the passivation structure, which greatly reduces the difficulty of depositing the passivation layer, has strong operability and high deposition efficiency; in addition, the obtained deposition structure is more compact; when the passivation structure is used in solar cells, the obtained cell has a high conversion efficiency (Eta) (about 26.5-26.6%) and a long minority carrier lifetime (about 1420-1690μs). BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 .Al of this application 2 O 3 / SiO 2 Schematic diagram of the structure of the passivation device; 1 refers to Al 2 O 3 layer, 2 refers to SiO 2 Layer, 3 refers to the silicon wafer substrate. Specific implementation methods

[0051] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in components' functions as the criterion for distinction.

[0052] As mentioned throughout the specification and claims, "including" or "comprising" is an open term and should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present application, but the description is for the purpose of the general principles of the specification and is not intended to limit the scope of the present application. The scope of protection of the present application shall be determined by the attached claims. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by ordinary technicians in the field to which the present disclosure belongs.

[0053] It should be understood that the embodiments of the present application described herein include "consisting of" and / or "consisting essentially of" embodiments. References to "about" a value or parameter herein include (and describe) variations to the value or parameter itself. For example, a description referring to "about X" includes a description of "X".

[0054] As used herein, reference to a "not" value or parameter generally means and describes an "except" value or parameter. For example, the method is not used to treat cancer type X, meaning that the method is used to treat cancers other than type X.

[0055] As used herein, the term "about XY" has the same meaning as "about X to about Y."

[0056] As used herein and in the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. It should also be noted that the claims may be drafted to exclude any optional elements. This statement is therefore intended to serve as antecedent basis for the use of exclusive terminology such as "only", "only" and the like in connection with the recitation of claim elements, or the use of a limitation of "no".

[0057] As used herein, the term "and / or" in phrases such as "A and / or B" is intended to include both A and B; A or B; A (alone); and B (alone). Similarly, as used herein, the term "and / or" in phrases such as "A, B, and / or C" is intended to include each of the following embodiments: A, B, and C; A, B, or C; A or C; A or B; B or C; A and C; A and B; B and C; A (alone); B (alone); and C (alone).

[0058] The present application provides an Al2O3 for photovoltaic solar cells. 2 O 3 / SiO 2 A deposition method for a passivation device, the deposition method comprising:

[0059] The first SiO 2 Deposition: Plasma enhanced atomic layer deposition (PEALD) is used to heat and ionize the silicon wafer substrate in a laughing gas environment to deposit the first SiO 2 layer; the first SiO 2 During deposition, the amount of laughing gas introduced is 5000-20000sccm;

[0060] First time Al 2 O 3 Deposition: The silicon wafer substrate is heated in a laughing gas and trimethylaluminum environment to deposit the first Al 2 O 3 layer; the first Al 2 O 3 During deposition, the volume ratio of the amount of the laughing gas introduced to the amount of the trimethylaluminum introduced is (6-40):(1-4), preferably (6-15):(1-2).

[0061] In this application, Al 2 O 3 / SiO 2 The passivation layer is deposited by using PEALD technology, which places the silicon wafer substrate in the PEALD reaction chamber. Its advantages are: 2Layer and Al 2 O 3 The deposition of the layers is carried out in one device, making the deposition process more efficient and simple. At the same time, the deposited layer (also the deposited film) obtained by this method is more dense. The passivation layer of the present application is Al 2 O 3 / SiO 2 The laminated structure can significantly improve the obtained passivation device (for example, applying it to a solar cell) with a higher minority carrier lifetime, and the obtained solar cell has better minority carrier lifetime (μs), Voc (open circuit voltage, V), Isc (short circuit current, A), FF (fill factor, %) and Eta (conversion efficiency, %); especially the minority carrier lifetime (μs) and Eta (conversion efficiency, %) are significantly better than the prior art. The solar cell obtained in this application has a minority carrier lifetime in the range of 1321-1683μs and a conversion efficiency in the range of 26.513-26.598%. In the scheme of the application, compared with only laminating one layer of Al 2 O 3 / SiO 2 In contrast, by setting up multi-layer Al 2 O 3 / SiO 2 Laminated films, such as 2 or 3 layers, can significantly improve the minority carrier lifetime and conversion efficiency of the resulting solar cell. 2 O 3 / SiO 2 Change to two layers of Al 2 O 3 / SiO 2 The minority carrier lifetime of solar cells increased from 1322μs to 1531μs, an increase of at least 15.81%; the conversion efficiency of solar cells increased from 26.528% to 26.581%, an increase of at least 0.053%. 2 O 3 / SiO 2 Change to three-layer Al 2 O 3 / SiO 2 The stacked film increases the minority carrier lifetime of solar cells from 1322μs to 1683μs at most, an increase of 27.31%, or even more, such as 28%, 29% or 30%; the conversion efficiency of solar cells increases from 26.528% to 26.598% at most, an increase of 0.070%, or even more, such as 0.072%, 0.075%, etc. For solar cells, an increase of 0.05% in cell efficiency is very difficult and a very significant technological advancement, especially when the cell efficiency itself is already as high as 26%.

[0062] The first SiO 2 The deposition process uses the silicon element present in the silicon wafer substrate as the silicon source, and additionally introduces laughing gas to deposit the first SiO 2 In some embodiments, the first SiO 2 During deposition, the amount of the laughing gas introduced is any range within the range of 5000-20000sccm, 7000-19000sccm, 8000-18000sccm, 9000-16000sccm, 10000-14000sccm, 11000-13000sccm or 5000-20000sccm; in a specific embodiment, the amount of the laughing gas introduced is, for example, 5000sccm, 6000sccm, 8000-19000sccm, 8000-18000sccm, 9000-16000sccm, 10000-14000sccm, 11000-13000sccm or 5000-20000sccm. In some preferred embodiments, the amount of the laughing gas is 8000-18000sccm; in some specific embodiments, within the range of the amount of the laughing gas, the minority carrier lifetime and conversion efficiency of the solar cell are at a higher level, for example, the minority carrier lifetime is 1536-1863μs, and the conversion efficiency is 26.564-26.598%.

[0063] In some embodiments, the first SiO 2 During deposition, the heating temperature is 200-500° C., 250-450° C., 200-400° C., 250-350° C. or any temperature in the range of 200-500° C. For example, the heating temperature is 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., 410° C., 420° C., 430° C., 440° C., 450° C., 460° C., 470° C., 480° C., 490° C., 500° C. or any temperature in the range of 200-500° C. Wherein, the heating temperature is the deposition temperature.

[0064] The first Al 2 O 3 The deposition is carried out using trimethylaluminum (TMA) as the aluminum source, and additional laughing gas is introduced to deposit the first Al 2 O3 Layer. When depositing this layer, under the condition of ensuring a certain gas flow rate, the volume ratio of trimethylaluminum (TMA) and laughing gas is more important, which obviously affects the passivation layer performance obtained, and then affects the performance of, for example, solar cells. In some embodiments, the volume ratio of the intake amount of the laughing gas and the intake amount of the trimethylaluminum is (6-40): (1-4), (6-40): (1-3), (6-40): (1-2), (6-35): (1-4), (6-30): (1-4), (6-25): (1-4), (6-20): (1-4), (6-15): (1-4), (6-10): ( 1-4), (6-5):(1-4), (6-30):(1-3), (6-30):(1-2), (6-15):(1-3), (6-15):(1-2), or (6-40):(1-4); for example, 6:4, 6:1, 6:2, 6:3, 8:1, 8:2, 8:3, 8:4, 10:1, 10:2, 10:3, 10:4 , 12:1, 12:2, 12:3, 12:4, 14:1, 14:2, 14:3, 14:4, 16:1, 16:2, 16:3, 16:4, 18:1, 18:2, 18:3, 18:4, 20:1, 20:2, 20:3, 20:4, 22:1, 22:2, 22:3, 22:4, 24:1, 24:2, 24:3, 24:4, 26:1 , 26:2, 26:3, 26:4, 28:1, 28:2, 18:3, 28:4, 30:1, 30:2, 30:3, 30:4, 32:1, 32:2, 32:3, 32:4, 34:1, 34:2, 34:3, 34:4, 36:1, 36:2, 36:3, 36:4, 38:1, 38:2, 38:3, 38:4, 40:1, 40:3. In some preferred embodiments, the volume ratio of the intake of the laughing gas and the intake of the trimethylaluminum is (6-15):(1-2); for example, specifically can be 6:1, 6:2, 7:1, 7:2, 8:1, 8:2, 9:1, 9:2, 10:1, 10:2, 11:1, 11:2, 12:1, 12:2, 13:1, 13:2, 14:1, 14:2, 15:1, 15:2 or (6-15): any ratio within the scope of (1-2).

[0065] In some embodiments, before depositing the first Al 2 O 3In a specific embodiment, the feeding amount of described laughing gas is for example any feeding amount in 300sccm, 400sccm, 500sccm, 600sccm, 700sccm, 800sccm, 900sccm, 1000sccm, 1100sccm, 1200sccm, 1300sccm, 1400sccm, 1500sccm, 1600sccm, 1700sccm, 1800sccm, 1900sccm, 2000sccm or the 300-2000sccm scope. In some preferred embodiments, the amount of laughing gas introduced is 500-1200 sccm.

[0066] In some embodiments, before depositing the first Al 2 O 3 In a specific embodiment, the amount of trimethylaluminum introduced is, for example, 50 sccm, 60 sccm, 70 sccm, 80 sccm, 90 sccm, 100 sccm, 110 sccm, 120 sccm, 130 sccm, 140 sccm, 150 sccm, 160 sccm, 170 sccm, 180 sccm, 190 sccm, 200 sccm or any amount within the range of 50-200 sccm. In some preferred embodiments, the amount of trimethylaluminum introduced is 80-150 sccm.

[0067] In some more preferred embodiments, the first Al 2 O 3 During deposition, the volume ratio of the amount of the laughing gas introduced and the amount of the trimethylaluminum introduced is (6-15):(1-2), the amount of the laughing gas introduced is 500-1200sccm, and the amount of the trimethylaluminum introduced is 80-150sccm; in some specific embodiments, it is seen that under this condition (such as Example 1 and Example 11 to Example 13), the minority carrier lifetime and conversion efficiency of the solar cell are at a higher level, for example, the minority carrier lifetime is 1532-1863μs, and the conversion efficiency is 26.583-26.598%.

[0068] In some embodiments, the first Al 2 O 3 During deposition, the heating temperature is 200-500° C., 250-450° C., 200-400° C., 250-350° C. or any temperature in the range of 200-500° C. For example, the heating temperature is 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., 410° C., 420° C., 430° C., 440° C., 450° C., 460° C., 470° C., 480° C., 490° C., 500° C. or any temperature in the range of 200-500° C. Wherein, the heating temperature is the deposition temperature.

[0069] The second SiO 2 The deposition is carried out using silane as the silicon source and additionally introducing nitrous oxide to deposit SiO 2 When depositing the layer, the volume ratio of silane to nitrous oxide is relatively important while ensuring a certain gas flow rate, which significantly affects the performance of the passivation layer obtained, and thus affects the performance of, for example, the solar cell. 2During deposition, the volume ratio of the amount of the laughing gas introduced and the amount of the silane introduced is (40-140): (7-33), (40-140): (10-28), (40-140): (10-23), (40-140): (9-20), (40-140): (12-18), (60-120): (7-33), (60-120): (10-28), (60-120): (10-23), (60-120): (9-20), (60-120): (12-18), (80-100): (7-33), (80-100): (10-28), (80-100): (10-23), (80-100) :(9-20), (80-100):(12-18) or (40-140):(7-33); for example, 40:7, 40:8, 40:9, 40:10, 40:11, 40:12, 40:13, 40:14, 40:15, 40:16, 40:17, 40:18, 40:19, 40:20, 40:21, 40:22, 40:23, 40:24, 40:25, 40:26, 40:27, 40:28, 40:29, 40:30, 40:31, 40:32, 40:33, 50:7, 50:8, 50:9, 50:10, 50:11, 50:12, 50:13 3. 50:14, 50:15, 50:16, 50:17, 50:18, 50:19, 50:20, 50:21, 50:22, 50:23, 50:24, 50:25, 50:26, 50:27, 50:28, 50:29, 50:30, 50:31, 50:32, 50:33, 60 :9, 60:10, 60:11, 60:12, 60:13, 60:14, 60:15, 60:16, 60:17, 60:18, 60:19, 60:20, 60:21, 60:22, 60:23, 60:24, 60:25, 60:26, 60:27, 60:28, 60:29, 60 :30, 60:31, 60:32, 60:33, 70:7, 70:8, 70:9, 70:10, 70:11, 70:12, 70:13, 70:14, 70:15, 70:16, 70:17, 70:18, 70:19, 70:20, 70:21, 70:22, 70:23, 70:2 4. 70:25, 70:26, 70:27, 70:28, 70:29, 70:30, 70:31, 70:32, 70:33, 80:7, 80:8, 80:9, 80:10, 80:11, 80:12, 80:13, 80:14, 80:15, 80:16, 80:17, 80:18,80:19、80:20、80:21、80:22、80:23、80:24、80:25、80:26、80:27、80:28、80:29、80:30、80:31、80:32、80:33、90:9、90:10、90:11、90:12、90:13、90:14、90:15、90:16、90:17、90:18、90: 19, 90:20, 90:21, 90:22, 90:23, 90:24, 90:25, 90:26, 90:27, 90:28, 90:29, 90:30, 90:31, 90:32, 90:33, 110:7, 110:8, 110:9, 110:10, 110:11, 110:12, 110:13, 110:14, 110:15, 110:16 、110:17、110:18、110:19、110:20、110:21、110:22、110:23、110:24、110:25、110:26、110:27、110:28、110:29、110:30、110:31、110:32、110:33、140:7、140:8、140:9、140:10、140:11、1 40:12, 140:13, 140:14, 140:15, 140:16, 140:17, 140:18, 140:19, 140:20, 140:21, 140:22, 140:23, 140:24, 140:25, 140:26, 140:27, 140:28, 140:29, 140:30, 140:31, 140:32, 140:33. In some preferred embodiments, the volume ratio of the amount of the laughing gas introduced to the amount of the silane introduced is (50-90): (10-23).

[0070] In some embodiments, the second SiO 2During deposition, the feeding amount of described laughing gas is any range in the scope of 4000-14000sccm, 5000-13000sccm, 6000-12000sccm, 5000-11000sccm, 6000-10000sccm, 7000-9000sccm or 4000-14000sccm; In a specific embodiment, the feeding amount of described laughing gas is, for example, any feeding amount in the scope of 4000sccm, 5000sccm, 6000sccm, 7000sccm, 8000sccm, 9000sccm, 10000sccm, 11000sccm, 12000sccm, 13000sccm, 14000sccm or 4000-14000sccm. In some preferred embodiments, the amount of laughing gas introduced is 5000-9000 sccm.

[0071] In some embodiments, the second SiO 2 During deposition, the amount of silane introduced is any range within the range of 700-3300sccm, 900-3100sccm, 1100-2700sccm, 1000-2300sccm, 1300-2000sccm, 1500-1800sccm or 700-3300sccm; in a specific embodiment, the amount of silane introduced is, for example, 700sccm, 800sccm, 900sccm, 1000sccm, 1100sccm, 1200sccm, 1300sccm, 1 In some preferred embodiments, the silane is introduced in an amount of 1000-2300 sccm.

[0072] In some more preferred embodiments, the second SiO 2During deposition, the volume ratio of the intake of the laughing gas and the intake of the silane is (50-90):(10-23), the intake of the laughing gas is 5000-9000sccm, and the intake of the silane is 1000-2300sccm; in some specific embodiments, it is found that under this condition (such as Example 1, Example 15 to Example 17 and Example 19 to Example 21), the minority carrier lifetime and conversion efficiency of the solar cell are at a higher level, for example, the minority carrier lifetime is 1432-1863μs, and the conversion efficiency is 26.561-26.598%.

[0073] In some embodiments, the second SiO 2 During deposition, the heating temperature is 200-500° C., 250-450° C., 200-400° C., 250-350° C. or any temperature in the range of 200-500° C. For example, the heating temperature is 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., 410° C., 420° C., 430° C., 440° C., 450° C., 460° C., 470° C., 480° C., 490° C., 500° C. or any temperature in the range of 200-500° C. Wherein, the heating temperature is the deposition temperature.

[0074] In some embodiments of the present application, the second SiO 2 Deposition steps to obtain deposition on different Al 2 O 3 SiO 2 In some embodiments, the first Al 2 O 3 Deposition steps to obtain deposition on different SiO 2 Al on the layer 2 O 3 In some embodiments, the number of repetitions is 0-4 times; for example, no repetition, 1 time, 2 times, 3 times or 4 times. More preferably, the first repetition of Al 2 O 3 The deposition step is repeated twice; the second SiO 2 The deposition step is one time; that is, a three-layer Al 2 O 3 / SiO 2 Laminated structure.

[0075] In some embodiments, the SiO 2The thickness of the layer is any thickness range within the range of 2-4nm, 2.5-3.5nm, 2-3nm or 2-4nm; for example, it can be 2.0nm, 2.1nm, 2.2nm, 2.3nm, 2.4nm, 2.5nm, 2.6nm, 2.7nm, 2.8nm, 2.9nm, 3.0nm, 3.1nm, 3.2nm, 3.3nm, 3.4nm, 3.5nm, 3.6nm, 3.7nm, 3.8nm, 3.9nm, 4.0nm or any thickness within the range of 2-4nm. In some embodiments, the Al 2 O 3 The thickness of the layer is 2-5nm, 2.5-4.5nm, 2-4nm, 2.5-3.5nm or any thickness range within the range of 2-5nm; for example, it can be 2.0nm, 2.1nm, 2.2nm, 2.3nm, 2.4nm, 2.5nm, 2.6nm, 2.7nm, 2.8nm, 2.9nm, 3.0nm, 3.1nm, 3.2nm, 3.3nm, 3.4nm, 3.5nm, 3.6nm, 3.7nm, 3.8nm, 3.9nm, 4.0nm, 4.1nm, 4.2nm, 4.3nm, 4.4nm, 4.5nm, 4.6nm, 4.7nm, 4.8nm, 4.9nm, 5.0nm or any thickness within the range of 2-5nm.

[0076] It will be understood by those skilled in the art that the Al2O3 for photovoltaic solar cells of the present application is 2 O 3 / SiO 2 The deposition method of the passivation device can be implemented on any type of silicon wafer substrate, that is, there is no special requirement for the silicon wafer substrate. For example, the silicon wafer substrate can be a single crystal silicon wafer substrate, a polycrystalline silicon wafer substrate, or any combination of one or more of any solar cell to be passivated. When the silicon wafer substrate is a single crystal silicon wafer substrate, the silicon wafer substrate can be a single crystal P-type silicon wafer and / or a single crystal N-type silicon wafer. It can be understood that the silicon wafer substrate of the present application can be obtained commercially or homemade. In some embodiments, the silicon wafer substrate is obtained by a certain treatment process based on the original single crystal P-type silicon wafer or the original single crystal N-type silicon wafer. In some embodiments, the treatment process includes but is not limited to: any one or more combinations of texturing, alkali polishing, deposition (such as LPCVD deposition, PECVD deposition, ALD deposition, etc.), (high temperature) boron diffusion, (high temperature) phosphorus diffusion, laser processing, crystallization, and cleaning.

[0077] In some embodiments, the layer structure of the single crystal P-type silicon wafer includes: the original single crystal P-type silicon wafer, the first velvet layer and the polishing surface layer disposed on both sides of the original single crystal P-type silicon wafer, the tunneling oxide layer and the p-type polysilicon layer disposed outside the polishing surface layer on either side, the second velvet layer and the PN junction layer disposed outside the polishing surface layer where the tunneling oxide layer is not disposed, and the mask layers disposed on both sides. For example, in a specific embodiment, the layer structure of the single crystal P-type silicon wafer includes in sequence: the original single crystal P-type silicon wafer, the first velvet layer and the polishing surface layer disposed in sequence on both sides of the original single crystal P-type silicon wafer, the tunneling oxide layer deposited on the back side, the p-type polysilicon layer disposed on both sides, the second velvet layer and the PN junction layer located on the front side, and the mask layers disposed on both sides.

[0078] In some embodiments, the method for preparing the first suede layer comprises: placing the single crystal P-type silicon wafer in an alkaline solution; and performing double-sided texturing treatment to form the first suede layer disposed on both sides.

[0079] In some embodiments, the alkali in the alkali solution is sodium hydroxide; in some embodiments, the first suede layer is a pyramid-shaped suede.

[0080] In some embodiments, alkali polishing is performed after texturing; in some embodiments, a tower base-shaped polishing surface is formed after double-sided alkali polishing. It is understood that other specific parameters of the alkali polishing process can be referred to in the prior art.

[0081] In some embodiments, after polishing, the tunneling oxide layer and the initial polysilicon layer are deposited on the back side by LPCVD; in some embodiments, the thickness of the initial polysilicon layer is 50-200nm, for example, 50nm, 52nm, 54nm, 56nm, 58nm, 60nm, 62nm, 64nm, 66nm, 68nm, 70nm, 72nm, 74nm, 76nm, 78nm, 80nm, 82nm, 84nm, 86nm, 88nm, 90nm, 92nm, 94nm, 96nm, 98nm, 100nm, 105nm, 110nm In some embodiments, the tunneling oxide layer has a thickness of 1.5-2.0 nm, for example, 1.5 nm, 1.55 nm, 1.6 nm, 1.65 nm, 1.7 nm, 1.75 nm, 1.8 nm, 1.85 nm, 1.9 nm, 1.95 nm, 2.0 nm.

[0082] In some embodiments, the p-type polysilicon layer is obtained by a method comprising subjecting the initial polysilicon layer to high-temperature boron diffusion. In some embodiments, the temperature of the high-temperature boron diffusion is 900-1050°C, 920-1030°C, 950-1000°C, or any temperature range in the range of 900-1050°C; for example, it can be 900°C, 910°C, 920°C, 930°C, 940°C, 950°C, 960°C, 970°C, 980°C, 990°C, 1000°C, 1010°C, 1020°C, 1030°C, 1040°C, 1050°C, or any temperature in the range of 900-1050°C. In some embodiments, the boron doping concentration is 3×10 18 cm -3 -5×10 18 cm -3 Or any concentration range within this range; for example, it can be 3×10 18 cm -3 , 3.1×10 18 cm -3 , 3.2×10 18 cm -3 , 3.3×10 18 cm -3 , 3.4×10 18 cm -3 , 3.5×10 18 cm -3 , 3.6×10 18 cm -3 , 3.7×10 18 cm -3 , 3.8×10 18 cm -3 , 3.9×10 18 cm -3 4.0×10 18 cm -3 4.1×10 18 cm -3 4.2×10 18 cm -3 , 4.3×10 18 cm -3 , 4.4×10 18 cm -3 , 4.5×10 18 cm -3 , 4.6×10 18 cm -3 , 4.7×10 18 cm -3 , 4.8×10 18 cm -3 , 4.9×10 18cm -3 5.0×10 18 cm -3 or 3×10 18 cm -3 -5×10 18 cm -3 It is understandable that other specific parameters of high temperature boron diffusion can be referred to in the prior art.

[0083] In some embodiments, the method further includes a step of cleaning the monocrystalline P-type silicon wafer having the p-type polysilicon layer to clean the poly silicon coated thereon; and further includes a texturing process after cleaning to obtain a second velvet layer; in some embodiments, the second velvet layer is a pyramid-shaped velvet. It is understood that other specific parameters of the process can be referred to in the prior art.

[0084] In some embodiments, the step of preparing a PN junction is further included after obtaining the second velvet surface; in some embodiments, the PN junction layer is obtained by a method comprising high-temperature phosphorus diffusion; during high-temperature phosphorus diffusion, the high temperature is 800-950°C, 820-920°C, 850-900°C or any temperature in the range of 800-950°C; for example, it can be 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, 920°C, 930°C, 940°C, 950°C or any temperature in the range of 800-950°C. In some embodiments, the phosphorus doping concentration is 1×10 20 cm -3 -5×10 20 cm -3 , 2×10 20 cm -3 -4×10 20 cm -3 , 2.5×10 20 cm -3 -3.5×10 20 cm -3 or 1×10 20 cm -3 -5×10 20 cm -3 Any concentration range within the range; for example, it can be 1×10 20 cm -3 , 1.3×10 20 cm -3 , 1.6×10 20 cm -3 , 1.9×10 20 cm -3 , 2.1×10 20cm -3 、 2.4×10 20 cm -3 、 2.7×10 20 cm -3 、 3.0×10 20 cm -3 、 3.3×10 20 cm -3 、 3.4×10 20 cm -3 、 3.5×10 20 cm -3 、 3.6×10 20 cm -3 、 3.7×10 20 cm -3 、 3.8×10 20 cm -3 、 3.9×10 20 cm -3 、 4.0×10 20 cm -3 、 4.1×10 20 cm -3 、 4.2×10 20 cm -3 、 4.3×10 20 cm -3 、 4.4×10 20 cm -3 、 4.5×10 20 cm -3 、 4.6×10 20 cm -3 、 4.7×10 20 cm -3 、、 4.8×10 20 cm -3 、 4.9×10 20 cm -3 、 5.0×10 20 cm -3 或 1×10 20 cm -3 -5×10 20 cm -3In some embodiments, the thickness of the PN junction layer is any thickness range within the range of 200-300nm, 220-280nm, 240-260nm or 200-300nm; for example, it can be 200nm, 205nm, 210nm, 215nm, 220nm, 225nm, 230nm, 235nm, 240nm, 245nm, 250nm, 255nm, 260nm, 265nm, 270nm, 275nm, 280nm, 285nm, 290nm, 295nm, 300nm or any thickness within the range of 200-300nm. It is understood that other specific parameters for preparing the PN junction can be referred to in the prior art.

[0085] In some embodiments, after obtaining the PN junction layer, a step of preparing a mask layer is further included; in some embodiments, the mask layer is a silicon oxide mask layer; in some embodiments, the mask layer is prepared by laser. It is understood that the specific parameters of the process can be referred to in the prior art.

[0086] In some embodiments, a cleaning step is further included after obtaining the mask layer; in some embodiments, the cleaning step can be performed in a tank cleaning machine to remove the wrap-around and mask layers.

[0087] In some embodiments, after cleaning, a high-temperature diffusion step is further included, wherein the temperature of the high-temperature diffusion is 900-1050°C, for example, 900°C, 910°C, 920°C, 930°C, 940°C, 950°C, 960°C, 970°C, 980°C, 990°C, 1000°C, 1010°C, 1020°C, 1030°C, 1040°C, 1050°C; the time of the high-temperature diffusion is 60-180min, for example, 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min, 140min, 150min, 160min, 170min, 180min; during the high-temperature diffusion, N 2 The flow rate is 10000-20000sccm, for example, 10000sccm, 11000sccm, 12000sccm, 13000sccm, 14000sccm, 15000sccm, 16000sccm, 17000sccm, 18000sccm, 19000sccm, 20000sccm; H 2The flow rate is 500-10000 sccm, for example, 500 sccm, 1000 sccm, 2000 sccm, 3000 sccm, 4000 sccm, 5000 sccm, 6000 sccm, 7000 sccm, 8000 sccm, 9000 sccm, and 10000 sccm.

[0088] In some embodiments, the method for preparing the single crystal P-type silicon wafer comprises:

[0089] 1) The original single crystal P-type silicon wafer is subjected to a texturing process and double-sided texturing to form a pyramid-shaped velvet surface;

[0090] 2) The original single crystal P-type silicon wafer after texturing is alkali polished and double-sided polished to form a tower base-shaped polished surface;

[0091] 3) The polished original single crystal P-type silicon wafer undergoes an LPCVD process to deposit a 1.5-2.0nm tunneling oxide layer and 50-200nm Poly-Si on the back;

[0092] 4) Boron diffusion is performed at 800-950°C, and the boron doping concentration is 3×10 18 cm -3 -5×10 18 cm -3 , forming p-type poly-Si; for example, this step can be performed in a high-temperature diffusion furnace;

[0093] 5) Clean the poly plated on the front side and make the front surface texture at the same time to form a pyramid morphology; for example, use a chain cleaning machine for cleaning;

[0094] 6) Phosphorus diffusion is performed at 800-950° C. to form an n-type semiconductor on the front side to form a PN junction; the thickness of the obtained PN junction layer is 200-300 nm; for example, this step is performed in a high-temperature diffusion furnace;

[0095] 7) Laser production of a patterned silicon oxide mask layer;

[0096] 8) Remove the wrap-around and mask layers through a tank cleaning machine;

[0097] 9) Using high temperature tubular diffusion furnace, high temperature 900-1050℃, N 2 Flow rate 10000-20000sccm, H 2 Anneal for 60-180 min at a flow rate of 500-10000 sccm. Example

[0098] The specific embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the specific embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0099] Preparation Example

[0100] The specific method for preparing single crystal P-type silicon wafer is as follows:

[0101] 1) The original single crystal P-type silicon wafer undergoes a texturing process and double-sided texturing to form a pyramid-shaped texture surface;

[0102] 2) The silicon wafer after texturing is subjected to an alkali polishing process and double-sided polishing to form a tower base-shaped polishing surface;

[0103] 3) The polished silicon wafer undergoes an LPCVD process to deposit a 1.5nm tunnel oxide layer and 150nm Poly-Si on the back;

[0104] 4) Boron diffusion was performed in a high temperature diffusion furnace at 1000°C with a boron doping concentration of 4×10 18 cm -3 , forming p-type poly-Si;

[0105] 5) The chain cleaning machine cleans the poly coated on the front side and makes the front side texture at the same time, forming a pyramid morphology;

[0106] 6) Phosphorus diffusion was performed in a high temperature diffusion furnace at 900°C, with a phosphorus doping concentration of 3×10 20 cm -3 , an n-type semiconductor is formed on the front side to form a PN junction, and the thickness of the PN junction layer is 250nm;

[0107] 7) Laser production of a patterned silicon oxide mask layer;

[0108] 8) Use a tank cleaning machine to remove the wrap-around and mask layers.

[0109] 9) Using high temperature tubular diffusion furnace, high temperature 1000℃, N 2 Flow rate 15000sccm, H 2 Annealing was performed at a flow rate of 5000 sccm for 120 min.

[0110] Double-sided deposition of Al2O using PEALD equipment 3 / SiO 2 Passivated device.

[0111] Example 1. Three-layer SiO 2 +Al 2 O3 Structure of Al 2 O 3 / SiO 2 Passivation Devices

[0112] Al 2 O 3 / SiO 2 Deposition methods for passivated devices:

[0113] a) Load the single crystal P-type silicon wafer obtained by the above method into a graphite boat, and place the graphite boat in a PEALD reaction chamber.

[0114] b) Set the temperature to 300°C and introduce laughing gas (N 2 O) and ionized (through RF power supply to cause gas glow discharge), in 10000sccm of laughing gas (N 2 O), 10000w RF power and 50:1000ms duty cycle, a first SiO2 layer with a thickness of 3nm was deposited on the silicon substrate. 2 layer;

[0115] c) Set the temperature to 300°C, and introduce 100 sccm of trimethylaluminum (TMA) and 800 sccm of nitrous oxide (N 2 O), under the condition of RF power of 5000w, the first SiO 2 A first Al layer with a thickness of 4 nm is deposited on the 2 O 3 layer;

[0116] d) By PEALD method, 1500 sccm of silane and 6000 sccm of laughing gas (N 2 O), obtained by depositing on the first Al 2 O 3 The second SiO layer with a thickness of 3 nm 2 layer;

[0117] e), repeat step c) to obtain a layer deposited on the second SiO 2 The second Al 2 O 3 layer.

[0118] f), accordingly, repeat steps d) and e) once to obtain a three-layer SiO 2 / Al 2 O 3 The passivation device structure is silicon substrate + SiO 2 Layer+Al 2 O 3 Layer+SiO 2 Layer+Al 2O 3 Layer+SiO 2 Layer+Al 2 O 3 Layer, specific reference Figure 1 shown.

[0119] Example 2. Single-layer SiO 2 +Al 2 O 3 Structure of Al 2 O 3 / SiO 2 Passivation Devices

[0120] Al 2 O 3 / SiO 2 Deposition methods for passivated devices:

[0121] a) Load a single crystal P-type silicon wafer into a graphite boat, and place the graphite boat in a PEALD reaction chamber.

[0122] b) Set the temperature to 300°C and introduce laughing gas (N 2 O) and ionized in 10000sccm of laughing gas (N 2 O), 10000w RF power and 50:1000ms duty cycle, a first SiO2 layer with a thickness of 3nm was deposited on the silicon substrate. 2 layer;

[0123] c) Set the temperature to 300°C, and introduce 100 sccm of trimethylaluminum (TMA) and 800 sccm of nitrous oxide (N 2 O), under the condition of RF power of 5000w, the first SiO 2 A first Al layer with a thickness of 4 nm is deposited on the 2 O 3 layer.

[0124] Example 3. Double-layer SiO 2 +Al 2 O 3 Structure of Al 2 O 3 / SiO 2 Passivation Devices

[0125] Al 2 O 3 / SiO 2 Deposition methods for passivated devices:

[0126] a) Load a single crystal P-type silicon wafer into a graphite boat, and place the graphite boat in a PEALD reaction chamber.

[0127] b) Set the temperature to 300°C and introduce laughing gas (N 2 O) and ionized (through RF power supply to cause gas glow discharge), in 10000sccm of laughing gas (N 2 O), 10000w RF power and 50:1000ms duty cycle, a first SiO2 layer with a thickness of 3nm was deposited on the silicon substrate. 2 layer;

[0128] c) Set the temperature to 300°C, and introduce 100 sccm of trimethylaluminum (TMA) and 800 sccm of nitrous oxide (N 2 O), under the condition of RF power of 5000w, the first SiO 2 A first Al layer with a thickness of 4 nm is deposited on the 2 O 3 layer;

[0129] d) By PEALD method, 1500 sccm of silane and 6000 sccm of laughing gas (N 2 O), obtained by depositing on the first Al 2 O 3 The second SiO layer with a thickness of 3 nm 2 layer;

[0130] e), repeat step c) to obtain a layer deposited on the second SiO 2 The second Al 2 O 3 layer.

[0131] Example 4. Four-layer SiO 2 +Al 2 O 3 Structure of Al 2 O 3 / SiO 2 Passivation Devices

[0132] Al 2 O 3 / SiO 2 Deposition methods for passivated devices:

[0133] a) Load a single crystal P-type silicon wafer into a graphite boat, and place the graphite boat in a PEALD reaction chamber.

[0134] b) Set the temperature to 300°C and introduce laughing gas (N 2 O) and ionized (through RF power supply to cause gas glow discharge), in 10000sccm of laughing gas (N 2O), 10000w RF power and 50:1000ms duty cycle, a first SiO2 layer with a thickness of 3nm was deposited on the silicon substrate. 2 layer;

[0135] c) Set the temperature to 300°C, and introduce 100 sccm of trimethylaluminum (TMA) and 800 sccm of nitrous oxide (N 2 O), under the condition of RF power of 5000w, the first SiO 2 A first Al layer with a thickness of 4 nm is deposited on the 2 O 3 layer;

[0136] d) By PEALD method, 1500 sccm of silane and 6000 sccm of laughing gas (N 2 O), obtained by depositing on the first Al 2 O 3 The second SiO layer with a thickness of 3 nm 2 layer;

[0137] e), repeat step c) to obtain a layer deposited on the second SiO 2 The second Al 2 O 3 layer.

[0138] f), accordingly, repeat steps d) and e) twice to obtain a three-layer SiO 2 / Al 2 O 3 The passivation device structure is silicon substrate + SiO 2 Layer+Al 2 O 3 Layer+SiO 2 Layer+Al 2 O 3 Layer+SiO 2 Layer+Al 2 O 3 layer.

[0139] The device obtained in the above embodiment is subjected to the following treatment:

[0140] The front and back silicon nitride anti-reflection films (thickness of both films is 60-100nm) are deposited by PECVD. Then, silver paste is screen-printed on the front and back to form metal grid lines on the front and back to transmit current. Finally, ohmic contact is formed by light injection equipment and laser sintering technology. The cell is tested to obtain the cell efficiency.

[0141] Specifically, the minority carrier lifetime (μs) of the passivated device was obtained by testing with the American Sinton WCT-120 minority carrier tester; the Voc (open circuit voltage, V), Isc (short circuit current, A), FF (fill factor, %) and Eta (conversion efficiency, %) of the passivated device were measured with a photovoltaic IV tester. The results of Examples 1 to 4 are shown in Table 1.

[0142] Table 1 Performance of passivated devices obtained by different implementation schemes

[0143]

[0144] Example 5. Three-layer SiO 2 +Al 2 O 3 Structure of Al 2 O 3 / SiO 2 Passivation Devices

[0145] Al 2 O 3 / SiO 2 Deposition methods for passivated devices:

[0146] a) Load a single crystal N-type silicon wafer into a graphite boat, and place the graphite boat in a PEALD reaction chamber.

[0147] b) Set the temperature to 300°C and introduce laughing gas (N 2 O) and ionized (through RF power supply to cause gas glow discharge), in 10000sccm of laughing gas (N 2 O), 10000w RF power and 50:1000ms duty cycle, a first SiO2 layer with a thickness of 3nm was deposited on the silicon substrate. 2 layer;

[0148] c) Set the temperature to 300°C, and introduce 100 sccm of trimethylaluminum (TMA) and 800 sccm of nitrous oxide (N 2 O), under the condition of RF power of 5000w, the first SiO 2 A first Al layer with a thickness of 4 nm is deposited on the 2 O 3 layer;

[0149] d) By PEALD method, 1500 sccm of silane and 6000 sccm of laughing gas (N 2 O), obtained by depositing on the first Al 2 O 3 The second SiO layer with a thickness of 3 nm 2 layer;

[0150] e), repeat step c) to obtain a layer deposited on the second SiO 2 The second Al 2 O 3 layer.

[0151] f), accordingly, repeat steps d) and e) once to obtain a three-layer SiO 2 / Al 2 O 3 The passivation device structure is silicon substrate + SiO 2 Layer+Al 2 O 3 Layer+SiO 2 Layer+Al 2 O 3 Layer+SiO 2 Layer+Al 2 O 3 layer.

[0152] According to the above method, Al 2 O 3 / SiO 2 The performance of the passivation device was tested, and the results were: minority carrier lifetime (μs) was 1843; Voc (open circuit voltage, V) was 0.7289; Isc (short circuit current, A) was 14.331; FF (fill factor, %) was 85.79; Eta (conversion efficiency, %) was 26.678.

[0153] Embodiment 6-9

[0154] The difference between Example 6-9 and Example 1 is that the amount of laughing gas in step b) is different. Specifically:

[0155] In Example 6, the amount of laughing gas in step b) is 5000 sccm; in Example 7, the amount of laughing gas in step b) is 8000 sccm; in Example 8, the amount of laughing gas in step b) is 18000 sccm; in Example 9, the amount of laughing gas in step b) is 20000 sccm; some process parameters in each embodiment are shown in Table 2.

[0156] Examples 10-13

[0157] The difference between Examples 10-13 and Example 1 is that the amount of laughing gas in step c) is different. Specifically:

[0158] In Example 10, the amount of laughing gas in step c) is 300 sccm; in Example 11, the amount of laughing gas in step c) is 500 sccm; in Example 12, the amount of laughing gas in step c) is 1000 sccm; in Example 13, the amount of laughing gas in step c) is 1200 sccm; some process parameters in each embodiment are shown in Table 2.

[0159] Examples 14-17

[0160] The difference between Examples 14-17 and Example 1 is that the amount of silane in step d) is different. Specifically:

[0161] In Example 14, the amount of silane in step d) is 700 sccm; in Example 15, the amount of silane in step c) is 1000 sccm; in Example 16, the amount of silane in step d) is 2000 sccm; in Example 17, the amount of silane in step d) is 2300 sccm; some process parameters in each embodiment are shown in Table 2.

[0162] Examples 18-21

[0163] The difference between Examples 18-21 and Example 1 is that the amount of laughing gas in step d) is different. Specifically:

[0164] In Example 18, the amount of laughing gas in step d) is 4000sccm; in Example 19, the amount of laughing gas in step c) is 5000sccm; in Example 20, the amount of laughing gas in step d) is 8000sccm; in Example 21, the amount of laughing gas in step d) is 9000sccm; some process parameters in each embodiment are shown in Table 2.

[0165] Referring to the above method, the device obtained in the above embodiment or comparative example is subjected to the following treatment:

[0166] The front and back silicon nitride anti-reflection films (thickness of both films is 60-100nm) are deposited by PECVD. Then, silver paste is screen-printed on the front and back to form metal grid lines on the front and back to transmit current. Finally, ohmic contact is formed by light injection equipment and laser sintering technology. The cell is tested to obtain the cell efficiency.

[0167] Specifically, the Al obtained from different implementation schemes is measured. 2 O 3 / SiO 2 The following performances of the passivated device are as shown in Table 2: minority carrier lifetime (μs), Voc (open circuit voltage, V), Isc (short circuit current, A), FF (fill factor, %) and Eta (conversion efficiency, %).

[0168] Table 2 Performance of passivated devices obtained by different implementation schemes

[0169]

[0170]

[0171] As can be seen from the data results of Table 2, when preparing the passivation device, its process parameters, especially the gas flow rate, have a certain influence on the performance (such as minority carrier lifetime (μs), Voc (open circuit voltage, V), Isc (short circuit current, A), FF (fill factor, %) and Eta (conversion efficiency, %), etc.) of the device finally obtained. Wherein, when the laughing gas flow rate of step b) is 8000-18000sccm, the laughing gas flow rate of step c) is 500-1200sccm, and the silane flow rate of step d) is 1000-2300sccm and the laughing gas flow rate is 5000-9000sccm, the performance of the device obtained is excellent.

[0172] The description of the present disclosure is given for the purpose of illustration and description, and is not intended to be exhaustive or to limit the present disclosure to the disclosed form. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present disclosure, and to enable those of ordinary skill in the art to understand the present disclosure and thereby design various embodiments with various modifications suitable for specific uses.

Claims

1. A deposition method for an Al2O3 / SiO2 passivation device for a photovoltaic solar cell, the deposition method comprising: First SiO2 deposition: using plasma enhanced atomic layer deposition (PEALD) technology, the silicon wafer substrate is heated and ionized in a laughing gas environment to deposit a first SiO2 layer; during the first SiO2 deposition, the amount of laughing gas introduced is 5000-20000 sccm; First Al2O3 deposition: the silicon wafer substrate is heated in a laughing gas and trimethylaluminum environment to deposit a first Al2O3 layer; during the first Al2O3 deposition, the volume ratio of the amount of laughing gas introduced to the amount of trimethylaluminum introduced is (6-40):(1-4), preferably (6-15):(1-2).

2. The deposition method according to claim 1, wherein during the first SiO2 deposition, the amount of laughing gas introduced is 8000-18000sccm; And / or, the heating temperature is 200-500°C.

3. The deposition method according to any one of claims 1 to 3, wherein during the first Al2O3 deposition, the amount of nitrous oxide introduced is 300-2000 sccm; preferably 500-1200 sccm; And / or, the heating temperature is 200-500°C; And / or, the amount of trimethylaluminum introduced is 50-200 sccm; preferably 80-150 sccm.

4. The deposition method according to any one of claims 1 to 3, further comprising: Second SiO2 deposition: heating the silicon wafer substrate after Al2O3 deposition and SiO2 deposition in an environment of laughing gas and silane to obtain a deposited second SiO2 layer; Preferably, during the second SiO2 deposition, the volume ratio of the amount of the laughing gas to the amount of the silane is (40-140):(7-33), more preferably (50-90):(10-23).

5. The deposition method according to claim 4, wherein during the second SiO2 deposition, the amount of laughing gas introduced is 4000-14000sccm, preferably 5000-9000sccm; And / or, the amount of silane introduced is 700-3300 sccm, preferably 1000-2300 sccm; And / or, the heating temperature is 200-500°C.

6. The deposition method according to claim 4 or 5, further comprising: Repeating the second SiO2 deposition step to obtain SiO2 layers deposited on different Al2O3 layers; Repeating the first Al2O3 deposition step to obtain Al2O3 layers deposited on different SiO2 layers; Preferably, the repetition number is 0-4 times; more preferably 1-3 times.

7. According to the deposition method according to any one of claims 1 to 6, the ionization conditions during the first SiO2 deposition include: The RF power is 6000-15000w and the duty cycle is 50:100ms.

8. The deposition method according to any one of claims 1 to 7, wherein the silicon wafer substrate is selected from any one or more of a single crystal silicon wafer substrate, a polycrystalline silicon wafer substrate, and a solar cell to be passivated; Preferably, the silicon wafer substrate is a single crystal P-type silicon wafer and / or a single crystal N-type silicon wafer.

9. The deposition method according to claim 8, wherein the layer structure of the single crystal P-type silicon wafer comprises: An original single crystal P-type silicon wafer, a first velvet layer and a polishing layer arranged on both sides of the original single crystal P-type silicon wafer, a tunneling oxide layer and a p-type polysilicon layer arranged outside the polishing layer on either side, a second velvet layer and a PN junction layer arranged outside the polishing layer where the tunneling oxide layer is not arranged, and mask layers arranged on both sides.

10. The deposition method according to claim 9, wherein the preparation method of the first velvet layer comprises: placing the single crystal P-type silicon wafer in an alkaline solution; preferably, the alkali in the alkaline solution is sodium hydroxide; and / or, the tunneling oxide layer is obtained by LPCVD deposition; preferably, the thickness of the tunneling oxide layer is 1.5-2.0 nm; and / or, the p-type polysilicon layer is obtained by a method comprising high temperature boron diffusion; And / or, the PN junction layer is obtained by a method involving high temperature phosphorus diffusion.

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