Continuous coating method, device and system for passivation of I layer of heterojunction cell

Abstract

The invention relates to the technical field of passivation coating of heterojunction cells, in particular to a continuous coating method, device and system for passivation of an I layer of a heterojunction cell, and the method comprises the following steps: S1, presetting the temperature of a PECVD cavity to 220-260 DEG C, and feeding an N-type monocrystalline silicon wafer into the PECVD cavity; s2, starting a first power supply, introducing O2 and SiH4, setting the power of an electromagnetic field to be 100-600W, and obtaining an I1 layer on the surface of the N-type monocrystalline silicon wafer; s3, a second power source is started, SiH4 is introduced, the power of the electromagnetic field is set to be 100-400 W, and an I2 layer is obtained on the surface of the I1 layer; s4, a third power source is started, SiH4 and H2 are introduced, the power of the electromagnetic field is set to be 100-400 W, and an I3 layer is obtained on the surface of the I2 layer; s5, the N-type monocrystalline silicon wafer with the passivated I layer is sent out of the PECVD cavity; according to the method, O2 is introduced while the I1 layer is deposited so as to inhibit epitaxial growth caused by high temperature, and an electromagnetic field is matched, so that the film coating speed is greatly increased in a high-temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of passivation coating for heterojunction batteries, and in particular to a continuous coating method, device and system for passivation of layer I of heterojunction batteries. Background Art

[0002] The traditional HJT cell structure first deposits a very thin intrinsic amorphous silicon film (ia-Si:H) and an N-type amorphous silicon film (na-Si:H) on the front of an N-type single crystal silicon wafer (c-Si), and then deposits a very thin intrinsic amorphous silicon film (ia-Si:H) and a P-type amorphous silicon film (pa-Si:H) on the back of the silicon wafer to form a back surface field; then a transparent oxide conductive film (TCO) is deposited on both sides of the cell, and finally a metal electrode is made on the TCO.

[0003] In order to obtain efficient heterojunction cells, it is very important to passivate the I layer, which is one of the main reasons for the high Voc of the heterojunction. The I layer is used to passivate the composites and defects on the surface of the battery. Currently, the I layer on the market uses static low-temperature coating (about 200°). The reason for low-temperature coating is: if the I layer is passivated at high temperature, the effect is very poor. High temperature is particularly prone to epitaxial growth. Epitaxy is an important factor affecting the passivation of the I layer, so the temperature of the I layer is strictly controlled. Secondly, the I1 layer in contact with the silicon wafer needs to be deposited quickly to prevent epitaxial growth, so I1 requires high-power coating.

[0004] Therefore, how to prevent the epitaxial growth of the I1 layer in a high-temperature environment is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] The present invention provides a continuous coating method, device and system for passivation of layer I of heterojunction cells, so as to overcome the technical problem that epitaxial growth occurs at high temperatures in the existing static low-temperature coating process.

[0006] In order to solve the above technical problems, the present invention provides a continuous coating method for passivation of the I layer of a heterojunction battery, comprising the following steps: step S1, presetting the temperature of the PECVD chamber to 220-260°C, and feeding an N-type single crystal silicon wafer into the PECVD chamber; step S2, starting a first power supply, introducing 1-5sccm of O2 and 100-300sccm of SiH4, setting the power of the electromagnetic field to 100-600W, obtaining an I1 layer on the surface of the N-type single crystal silicon wafer, and setting the end pressure of the PECVD chamber to 15-60Pa; step S3, starting a second power supply , introduce 50-200sccm of SiH4, set the power of the electromagnetic field to 100-400W, obtain I2 layer on the surface of I1 layer, and set the terminal pressure of the PECVD chamber to 15-60Pa; step S4, start the third power supply, introduce 50-100sccm of SiH4 and 300-3000sccm of H2, set the power of the electromagnetic field to 100-400W, obtain I3 layer on the surface of I2 layer, and set the terminal pressure of the PECVD chamber to 15-60Pa; step S5, send the I layer passivated N-type single crystal silicon wafer out of the PECVD chamber.

[0007] Furthermore, the method further includes: step S6, performing WCT120 to test the minority carrier lifetime, and screening out N-type single crystal silicon wafers with I-layer passivation below 3000us.

[0008] Furthermore, the method further includes: step S7, performing IV test to screen out I-layer passivated N-type single crystal silicon wafers with a Voc lower than 0.700V.

[0009] Furthermore, the thickness of the I1 layer is 0.5-2 nm.

[0010] Furthermore, the thickness of the I2 layer is 0.5-2nm.

[0011] Furthermore, the thickness of the I3 layer is 2-4 nm.

[0012] On the other hand, the present invention also provides a continuous coating device, which is used for coating heterojunction solar cells with PECVD coating equipment using the continuous coating method as described above, and the coating device includes: a coating module, which is arranged above the inside of a PECVD chamber, and performs PECVD deposition according to at least three power sources in sequence while performing electromagnetic field guidance; at least one process pump is arranged at the end of the coating module; a transmission module, which is arranged below the inside of the PECVD chamber, and is used to transmit a carrier loaded with N-type single crystal silicon wafers through the PECVD chamber by rollers.

[0013] Furthermore, the at least three power sources include a first power source, a second power source and a third power source; the first power source is supplied with 1-5 sccm of O2 and 100-300 sccm of SiH4, and the power of the electromagnetic field is set to 100-600 W; the second power source is supplied with 50-200 sccm of SiH4, and the power of the electromagnetic field is set to 100-400 W; the third power source is supplied with 50-100 sccm of SiH4 and 300-3000 sccm of H2, and the power of the electromagnetic field is set to 100-400 W.

[0014] In a third aspect, the present invention further provides a continuous coating system, comprising the continuous coating device as described above, and a heterojunction cell, wherein the continuous coating device is used to deposit a layer of passivation film on the heterojunction cell.

[0015] The beneficial effects of the present invention are that the continuous coating method, device and system for passivation of layer I of heterojunction battery of the present invention have the following advantages:

[0016] 1. While depositing the I1 layer, O2 is introduced to suppress the epitaxial growth caused by high temperature. With the help of electromagnetic field, the ionized gas with charge is accelerated in the magnetic field under the action of magnetic force. The particles collide with the gas again to obtain greater speed and energy, making it easier to decompose the gas, thereby greatly improving the coating speed in a high temperature environment;

[0017] 2. The setting of magnetic field can also control the coating area, so that the coating is only carried out within the magnetic field range, achieving the effect of layering in a single cavity, which greatly reduces the volume of the equipment and also increases the coating rate;

[0018] 3. Due to the single-chamber design, only one process pump is required at the end of the coating module to control the direction and pressure of the airflow, which greatly reduces the gas flow rate;

[0019] 4. The improved process has greatly increased the minority carrier lifetime to 3000-4500us, and the Voc of the battery cell has also increased to 0.750V.

[0020] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description and the drawings.

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A schematic diagram of the structure of a heterojunction battery involved in an embodiment of the present disclosure;

[0024] Figure 2 It is a schematic structural diagram of the continuous coating device involved in the embodiment of the present disclosure.

[0025] In the figure:

[0026] 1. PECVD chamber; 21. first power supply; 22. second power supply; 23. third power supply; 31. first gas inlet; 32. second gas inlet; 33. third gas inlet; 4. roller; 5. carrier plate; 6. gate valve; 7. process pump. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] like Figure 1 As shown, the current technical solution for the I layer is: after the carrier enters the chamber, the temperature is raised to about 200 degrees, a certain ratio of H2 and SiH4 is introduced, and the appropriate RF power is turned on for deposition. During the coating process, the carrier is stationary. After depositing a layer of I1, the chamber gas is evacuated to prevent the gas from entering the next chamber. The chamber valve is opened, and the carrier enters the next chamber to continue to deposit I2, I3, etc. in the same way. Because the I layer needs to be made into multiple layers, and amorphous silicon cannot be high temperature, the temperature cannot exceed 200°C, otherwise it will cause epitaxial growth and destroy the passivation effect of amorphous silicon. Multiple layers of I need to be made separately in multiple chambers for the process, which increases the equipment cost and coating time. The same chamber cannot realize the entire I layer process. The I layer made by static coating at low temperature will narrow the process coating temperature window of thickness. The subsequent coating temperature cannot exceed 200°C, otherwise it will destroy the passivation effect of amorphous silicon, which is more difficult to debug, and the process time will be longer, especially the curing time of the screen process will be longer, because the silver paste on the battery cell cannot be cured at high temperature, so it will seriously affect the production capacity.

[0029] The defects existing in the above solutions are the results obtained by the inventor after practice and careful research. Therefore, the discovery process of the above problems and the solutions proposed by the present disclosure for the above problems below should be the contributions made by the inventor to the present disclosure during the disclosure process.

[0030] Based on the above research, the embodiment of the present disclosure provides a continuous coating method for passivation of the I layer of a heterojunction battery, comprising the following steps: step S1, presetting the temperature of the PECVD chamber to 220-260°C, and feeding an N-type single crystal silicon wafer into the PECVD chamber; step S2, starting the first power supply, introducing 1-5sccm of O2 and 100-300sccm of SiH4, setting the power of the electromagnetic field to 100-600W, obtaining an I1 layer on the surface of the N-type single crystal silicon wafer, and setting the end pressure of the PECVD chamber to 15-60Pa; step S3, starting the second power supply, introducing 50-200sccm of SiH4, setting the power of the electromagnetic field to 100-400W, and obtaining an I1 layer on the surface of the N-type single crystal silicon wafer. The I2 layer is obtained on the surface of the silicon wafer, and the terminal pressure of the PECVD chamber is set to 15-60Pa; Step S4, starting the third power supply, introducing 50-100sccm of SiH4 and 300-3000sccm of H2, the power of the electromagnetic field is set to 100-400W, and the I3 layer is obtained on the surface of the I2 layer, and the terminal pressure of the PECVD chamber is set to 15-60Pa; Step S5, sending the I-layer passivated N-type single crystal silicon wafer out of the PECVD chamber; Step S6, performing WCT120 to test the minority carrier lifetime, and screening out the I-layer passivated N-type single crystal silicon wafers with a lifetime lower than 3000us; Step S7, performing IV test, and screening out the I-layer passivated N-type single crystal silicon wafers with a Voc lower than 0.700V.

[0031] Specifically, the amount of O2 introduced in step S2 in the method embodiment is adjusted to obtain the parameters and performance of embodiments 1-2 and comparative example 1, as shown in Tables 1 and 2 below.

[0032] Table 1

[0033]

[0034] Table 2

[0035] Example <![CDATA[I1 Thickness / nm]]> <![CDATA[I2 thickness / nm]]> <![CDATA[I3 thickness / nm]]> Minority life span / us Voc / V Example 1 1 1.3 1.5 600 0.720 Example 2 1 1.3 1.5 4000 0.752 Example 3 1 1.3 1.5 3000 0.740

[0036] Specifically, the preset in step S1 in the method embodiment is adjusted to obtain the parameters and performances of embodiment 1, embodiment 4 and comparative example 2, as shown in Tables 3 and 4 below.

[0037] Table 3

[0038]

[0039] Table 4

[0040] Example <![CDATA[I1 thickness / nm]]> <![CDATA[I2 thickness / nm]]> <![CDATA[I3 thickness / nm]]> Minority life span / us Voc / V Comparative Example 2 1 1.3 1.5 1800 0.740 Example 4 1 1.3 1.5 3000 0.746 Example 1 1 1.3 1.5 4000 0.752

[0041] In the embodiments of the present disclosure, specifically, in Tables 1-4, the units of the amounts of O2, SiH4 and H2 are sccm, the units of pressure are Pa, and the units of temperature are °C.

[0042] In the embodiments of the present disclosure, specifically, the PECVD refers to plasma enhanced chemical vapor deposition, and the Voc refers to open circuit voltage.

[0043] In the embodiment of the present disclosure, specifically, step S1 also includes: introducing 200-400sccm of argon gas. In step S1, the amount of O2 introduced is less than that of SiH4, so it cannot be evenly introduced into the entire cavity. By mixing inert gas argon with O2 in advance, oxygen can be evenly introduced into all parts of the cavity. At the same time, argon does not participate in the process reaction, which can improve the reaction uniformity of O2 without affecting the process effect.

[0044] In the embodiments of the present disclosure, specifically, 64 N-type single crystal silicon wafers are evenly spaced on a carrier in an 8*8 arrangement, and the efficiency and minority carrier conditions are compared, wherein the control group without the introduction of argon gas is shown in the following Table 5 (whole plate efficiency) and Table 6 (minority carrier condition), and the implementation group with the introduction of 200sccm of argon gas is shown in the following Table 7 (whole plate efficiency) and Table 8 (minority carrier condition).

[0045] Table 5

[0046] X8 X7 X6 X5 X4 X3 X2 X1 coordinate 25.25 25.20 25.14 25.23 24.46 24.16 24.13 24.19 Y8 25.04 25.12 25.33 25.01 25.45 25.41 25.18 25.65 Y7 25.22 25.49 25.26 25.78 25.35 25.40 25.34 25.67 Y6 25.12 25.46 25.16 25.11 25.45 25.10 25.12 25.56 Y5 25.15 25.45 25.35 25.23 25.50 25.38 25.31 25.69 Y4 25.19 25.98 25.31 25.03 25.12 25.48 25.43 25.53 Y3 25.18 25.76 25.04 25.19 25.11 25.48 25.15 25.21 Y2 25.05 25.73 25.39 25.22 24.45 24.03 24.29 24.92 Y1

[0047] Table 6

[0048]

[0049]

[0050] Table 7

[0051] X8 X7 X6 X5 X4 X3 X2 X1 coordinate 25.65 25.41 25.29 25.20 25.61 25.35 25.21 25.14 Y8 25.89 25.41 25.29 25.20 25.49 25.30 25.20 25.14 Y7 25.71 25.40 25.29 25.19 25.49 25.29 25.20 25.13 Y6 25.61 25.40 25.28 25.19 25.48 25.28 25.19 25.12 Y5 25.43 25.40 25.27 25.18 25.45 25.26 25.18 25.12 Y4 25.43 25.38 25.24 25.18 25.39 25.25 25.16 25.11 Y3 25.42 25.33 25.24 25.71 25.37 25.24 25.15 25.10 Y2 25.42 25.31 25.23 25.65 25.37 25.23 25.15 25.10 Y1

[0052] Table 8

[0053] X8 X7 X6 X5 X4 X3 X2 X1 coordinate 3130 3770 3543 3071 3771 3146 3876 3586 Y8 3490 3267 3011 3393 3378 3517 3322 3202 Y7 3312 3102 3114 3716 3284 3835 3942 3097 Y6 3541 3342 3978 3182 3852 3481 3147 3706 Y5 3848 3323 3081 3231 3125 3495 3152 3406 Y4 3289 3442 3447 3123 3724 3857 3552 3340 Y3 3102 3422 3861 3493 3476 3925 3797 3329 Y2 3443 3213 3105 3579 3946 3240 3495 3720 Y1

[0054] In the embodiments of the present disclosure, specifically, from the comparison of Tables 5 to 8 above, it can be seen that after the introduction of argon gas, the edge efficiency uniformity and edge minority carrier uniformity of the entire plate are significantly improved.

[0055] like Figure 2As shown, at least one embodiment provides a continuous coating device, which is used in the coating of heterojunction solar cells by a PECVD coating device using the continuous coating method as described above, and the coating device includes: a coating module, which is arranged above the inside of a PECVD chamber 1, and performs PECVD deposition according to at least three power sources in sequence while performing electromagnetic field guidance; a transmission module, which is arranged below the inside of the PECVD chamber 1, and is used to transmit a carrier 5 loaded with N-type single crystal silicon wafers through the PECVD chamber 1 via a roller 4.

[0056] In the disclosed embodiment, specifically, at least one process pump 7 is provided at the end of the coating module. Since only one chamber is provided, only one process pump at the tail end is required to control the direction and pressure of the airflow, and no gate valve is required in the middle, so the equipment cost is greatly reduced.

[0057] In the embodiment of the present disclosure, specifically, the at least three power sources include a first power source 21, a second power source 22 and a third power source 23; the first power source 21 is supplied with 1-5 sccm of O2 and 100-300 sccm of SiH4, and the power of the electromagnetic field is set to 100-600 W; the second power source 22 is supplied with 50-200 sccm of SiH4, and the power of the electromagnetic field is set to 100-400 W; the third power source 23 is supplied with 50-100 sccm of SiH4 and 300-3000 sccm of H2, and the power of the electromagnetic field is set to 100-400 W.

[0058] In the embodiment of the present disclosure, specifically, the first gas inlet 31 is suitable for performing vapor deposition operations within the electromagnetic field range after the first power supply 21 is started, the second gas inlet 32 ​​is suitable for performing vapor deposition operations within the electromagnetic field range after the second power supply 22 is started, and the third gas inlet 33 is suitable for performing vapor deposition operations within the electromagnetic field range after the third power supply 23 is started.

[0059] In the embodiment of the present disclosure, specifically, since only one PECVD chamber 1 is provided, only one pair of gate valves 6 is required, thus eliminating the need for multiple pairs of gate valves and process pumps in existing multiple chambers.

[0060] At least one embodiment provides a continuous coating system, including a continuous coating device as described above, and a heterojunction cell, wherein the continuous coating device is used to deposit a layer of passivation film on the heterojunction cell.

[0061] In summary, the continuous coating method for passivation of the I layer of a heterojunction battery of the present invention introduces O2 while depositing the I1 layer to inhibit the epitaxial growth caused by high temperature, and cooperates with the electromagnetic field to accelerate the ionized gas with charge in the magnetic field under the action of the magnetic force. The particles collide with the gas again to obtain a greater speed and energy, and the gas is more easily decomposed, thereby greatly improving the coating speed in a high temperature environment. At the same time, the setting of the magnetic field can also control the coating area, so that the film is only coated within the magnetic field range, achieving the effect of layering the I layer in a single cavity, while greatly reducing the volume of the equipment, it also improves the coating rate.

[0062] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0063] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A continuous coating method for passivation of layer I of a heterojunction battery, characterized in that: The steps include: Step S1, preset the temperature of the PECVD chamber to 220-260° C., and place an N-type single crystal silicon wafer into the PECVD chamber; Step S2, start the first power supply, introduce 1-5 sccm of O2 and 100-300 sccm of SiH4, set the power of the electromagnetic field to 100-600W, obtain an I1 layer on the surface of the N-type single crystal silicon wafer, and set the end pressure of the PECVD chamber to 15-60 Pa; Step S3, start the second power supply, introduce 50-200 sccm of SiH4, set the power of the electromagnetic field to 100-400W, obtain the I2 layer on the surface of the I1 layer, and set the end pressure of the PECVD chamber to 15-60 Pa; Step S4, start the third power supply, introduce 50-100 sccm of SiH4 and 300-3000 sccm of H2, set the power of the electromagnetic field to 100-400W, obtain the I3 layer on the surface of the I2 layer, and set the end pressure of the PECVD chamber to 15-60 Pa; Step S5, sending the I-layer passivated N-type single crystal silicon wafer out of the PECVD chamber.

2. The continuous coating method for passivation of layer 1 of a heterojunction battery according to claim 1, characterized in that: Also includes: Step S6, performing WCT120 to test the minority carrier lifetime, and screening out N-type single crystal silicon wafers with I-layer passivation below 3000us.

3. The continuous coating method for passivation of layer 1 of a heterojunction battery according to claim 1, characterized in that: Also includes: Step S7, perform an IV test to screen out I-layer passivated N-type single crystal silicon wafers with a Voc lower than 0.700 V.

4. The continuous coating method for passivation of layer 1 of a heterojunction battery according to claim 1, characterized in that: The step S1 further comprises: 200-400 sccm of argon gas was introduced.

5. The continuous coating method for passivation of layer 1 of heterojunction battery according to claim 1, characterized in that: The thickness of the I1 layer is 0.5-2 nm.

6. The continuous coating method for passivation of layer 1 of a heterojunction battery according to claim 1, characterized in that: The thickness of the I2 layer is 0.5-2nm.

7. The continuous coating method for passivation of layer 1 of a heterojunction battery according to claim 1, characterized in that: The thickness of the I3 layer is 2-4 nm.

8. A continuous coating device, characterized in that: Applicable to coating heterojunction solar cells with a PECVD coating device using the continuous coating method according to any one of claims 1 to 6, the coating device comprising: The coating module is arranged above the interior of the PECVD chamber, and performs PECVD deposition and electromagnetic field guidance in sequence according to at least three power sources; At least one process pump is provided at the end of the coating module; The transmission module is arranged at the lower part of the PECVD chamber and is used to transmit the carrier loaded with N-type single crystal silicon wafers through the PECVD chamber through rollers.

9. The continuous coating device according to claim 7, characterized in that: The at least three power sources include a first power source, a second power source and a third power source; The first power source is fed with 1-5 sccm of O2 and 100-300 sccm of SiH4, and the power of the electromagnetic field is set to 100-600W; The second power source is fed with 50-200 sccm of SiH4, and the power of the electromagnetic field is set to 100-400W; The third power source is fed with 50-100 sccm of SiH4 and 300-3000 sccm of H2, and the power of the electromagnetic field is set to 100-400W.

10. A continuous coating system, characterized in that: It comprises a continuous coating device as described in claims 7-9, and a heterojunction cell, wherein the continuous coating device is used to deposit a layer of passivation film on the heterojunction cell.

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