Topcon solar cell back passivation film layer structure and preparation method thereof

Abstract

The invention belongs to the technical field of solar cells, and provides a Topcon solar cell back passivation film layer structure and a preparation method thereof. The back passivation film layer structure is a multi-layer back passivation laminated structure and sequentially comprises a silicon nitride film and a silicon oxide film; the number of layers of the silicon nitride film is 1-4, and the number of layers of the silicon oxide film is 1. According to the invention, the film layer design of the laminated back passivation film is carried out mainly from the aspects of optics and passivation, and the passivation effect of the back passivation film layer structure of the solar cell is improved by optimizing the film thickness and the refractive index of each layer, so that the conversion efficiency is improved. The electrical performance of the Sinx / Siox film layer structure is improved compared with that of a conventional Sinx film layer structure, the percent absolute value of the conversion efficiency of the back passivation battery is improved by more than 0.05%, and the reflectivity of the Sinx / Siox film layer structure is superior to that of Sinx in the wavelength range of 800-1000 nm from the aspect of optical reflectivity.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a back passivation film structure of a Topcon solar cell and a preparation method thereof. Background Art

[0002] In the production of crystalline silicon cells, cell back passivation is a technology that reduces the charge recombination loss on the back of the cell. There are a large number of defects on the cell surface, which will recombine with minority carriers, resulting in carrier loss and reduced electrical performance. By forming a passivation layer on the cell surface, surface defects can be reduced, the surface recombination rate can be reduced, and the minority carrier life of the silicon wafer can be increased.

[0003] With the continuous improvement of battery surface technology, battery efficiency has been greatly improved, but the serious optical and electrical losses on the back surface of the battery have become a bottleneck restricting the further improvement of battery efficiency. At present, the common back passivation technology is Sinx back passivation coating. The back passivation battery using silicon nitride passivation can not only greatly reduce the electrical recombination rate of the back surface, but also form a good internal optical back reflection mechanism. Among them, a good back passivation film layer structure design is one of the effective ways to improve the conversion efficiency of back passivation batteries. With the use of Sinx, the optimization of battery back passivation has entered a bottleneck stage. In order to increase the back light absorption and improve the conversion efficiency of the battery cell, it is urgent to combine Siox passivation materials to form a new back passivation structure.

[0004] Therefore, it is of great significance to provide a Topcon solar cell back passivation film structure and a preparation method thereof for improving electrical performance. Summary of the invention

[0005] The purpose of the present invention is to provide a Topcon solar cell back passivation film structure and a preparation method thereof in order to overcome the deficiencies of the prior art, mainly to optimize the film thickness and refractive index, adjust the film structure, realize the film layer optimization design of the multi-layer back passivation film, and improve the conversion efficiency of the solar cell.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The invention provides a back passivation film layer structure of a Topcon solar cell. The back passivation film layer structure is a multi-layer back passivation stacked structure, which sequentially comprises a silicon nitride film and a silicon oxide film; the number of layers of the silicon nitride film is 1 to 4, and the number of layers of the silicon oxide film is 1.

[0008] Preferably, the back passivation film structure sequentially comprises a bottom silicon nitride film, a second silicon nitride film, a third silicon nitride film, a fourth silicon nitride film and a fifth silicon oxide film; the bottom silicon nitride film has a thickness of 40 to 100 nm and a refractive index of 2.20 to 2.40; the second silicon nitride film has a thickness of 30 to 100 nm and a refractive index of 2.20 to 2.40; the

[0009] The thickness of the third layer of silicon nitride film is 100nm, and the refractive index is 2.10-2.20; the thickness of the fourth layer of silicon nitride film is 30-100nm, and the refractive index is 2.00-2.10; the thickness of the fifth layer of silicon oxide film is 10-30nm, and the refractive index is 1.45-1.50.

[0010] The present invention also provides a method for preparing the Topcon solar cell back passivation film structure, comprising the following steps:

[0011] A bottom silicon nitride film, a second silicon nitride film, a third silicon nitride film, a fourth silicon nitride film, and a fifth silicon oxide film are sequentially deposited on the back surface of the Topcon solar cell to obtain a back passivation film structure of the Topcon solar cell.

[0012] Preferably, during the deposition of the bottom silicon nitride film, the temperature is 420-550°C, the RF power is 12000-16000W, and the SiH 4 With NH 3 The flow ratio is 1:2~5, and the pressure is 1500~1700mtorr.

[0013] Preferably, during the deposition of the second silicon nitride film, the temperature is 420-550° C., the RF power is 12000-16000 W, and the SiH 4 With NH 3 The flow ratio is 1:5~10, and the pressure is 1500~1700mtorr.

[0014] Preferably, during the deposition of the third silicon nitride film, the temperature is 420-550° C., the RF power is 15000-18000 W, and the SiH 4 With NH 3 The flow ratio is 1:5~10, and the pressure is 1600~1800mtorr.

[0015] Preferably, during the deposition of the fourth silicon nitride film, the temperature is 420-550° C., the RF power is 15000-18000 W, and the SiH 4 With NH 3 The flow ratio is 1:5~15, and the pressure is 1600~1800mtorr.

[0016] Preferably, during the deposition of the fifth silicon oxide film, the temperature is 420-550° C., the RF power is 10000-15000 W, and the SiH 4 With N 20The flow ratio is 1:10~25, and the pressure is 1500~1700mtorr.

[0017] Preferably, during the deposition of the underlying silicon nitride film, SiH 4 The flow rate is 1000~3000sccm, NH 3 The flow rate is 5000~10000sccm; during the deposition of the second layer of silicon nitride film, SiH 4 The flow rate is 1000~2000sccm, NH 3 The flow rate is 3000~9000sccm. During the deposition of the third layer of silicon nitride film, SiH 4 The flow rate is 500~1000sccm, NH 3 The flow rate is 5000~10000sccm. During the deposition of the fourth layer of silicon nitride film, SiH 4 The flow rate is 500~1000sccm, NH 3 The flow rate is 5000~10000sccm. During the deposition of the fifth silicon oxide film, SiH 4 The flow rate is 500~1000sccm, N 20 The flow rate is 5000~15000sccm.

[0018] The beneficial effects of the present invention include the following:

[0019] 1) The present invention mainly designs the laminated back passivation film layer from the perspective of optics and passivation, and improves the passivation effect of the back passivation film layer structure of the solar cell by optimizing the film thickness and refractive index of each layer, thereby improving the conversion efficiency. The present invention effectively improves light absorption by optimizing the back passivation film layer structure of the back passivation cell, while improving the back surface passivation effect and improving the efficiency of the cell.

[0020] 2) The electrical properties of the solar cell back passivation film structure (Sinx / Siox film structure) of the present invention are improved compared with the conventional Sinx film structure, so that the absolute value of the conversion efficiency percentage of the back passivation cell is increased by more than 0.05%. From the perspective of optical reflectivity, the reflectivity of the Sinx / Siox film structure is superior to that of the Sinx film structure in the wavelength range of 800 to 1000 nm. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a comparison diagram of the reflectivity of the film layer structure of Example 1 and Comparative Example 1, wherein Sinx is Comparative Example 1, and Sinx / Siox is Example 1. DETAILED DESCRIPTION

[0022] The invention provides a back passivation film layer structure of a Topcon solar cell. The back passivation film layer structure is a multi-layer back passivation stacked structure, which sequentially comprises a silicon nitride film and a silicon oxide film; the number of layers of the silicon nitride film is 1 to 4, and the number of layers of the silicon oxide film is 1.

[0023] In the present invention, the back passivation film structure preferably comprises a bottom silicon nitride film, a second silicon nitride film, a third silicon nitride film, a fourth silicon nitride film and a fifth silicon oxide film in sequence; the thickness of the bottom silicon nitride film is preferably 40 to 100 nm, more preferably 50 to 80 nm, more preferably 60 to 70 nm, and the refractive index is preferably 2.20 to 2.40, more preferably 2.30 to 2.37; the thickness of the second silicon nitride film is preferably 30 to 100 nm, more preferably 40 to 80 nm, more preferably 50 to 65 nm, and the refractive index is preferably 2.10 to 2.20, more preferably 2.15 to 2.16; the thickness of the third silicon nitride film is preferably 40 to 80 nm, more preferably 50 to 65 nm, and the refractive index is preferably 2.10 to 2.20, more preferably 2.15 to 2.16; the thickness of the fourth ... fifth silicon nitride film is preferably 40 to 80 nm, more preferably 50 to 65 nm, and the refractive The thickness of the first silicon nitride film is preferably 30 to 100 nm, more preferably 40 to 80 nm, more preferably 50 to 65 nm, and the refractive index is preferably 2.10 to 2.20, more preferably 2.15 to 2.16; the thickness of the fourth silicon nitride film is preferably 30 to 100 nm, more preferably 40 to 80 nm, more preferably 50 to 65 nm, and the refractive index is preferably 2.00 to 2.10, more preferably 2.05; the thickness of the fifth silicon oxide film is preferably 10 to 30 nm, more preferably 15 to 20 nm, and the refractive index is preferably 1.45 to 1.50, more preferably 1.47 to 1.48.

[0024] The present invention also provides a method for preparing the Topcon solar cell back passivation film structure, comprising the following steps:

[0025] A bottom silicon nitride film, a second silicon nitride film, a third silicon nitride film, a fourth silicon nitride film, and a fifth silicon oxide film are sequentially deposited on the back surface of the Topcon solar cell to obtain a back passivation film structure of the Topcon solar cell.

[0026] In the process of depositing the bottom silicon nitride film of the present invention, the temperature is preferably 420-550°C, more preferably 450-520°C, more preferably 480-500°C, and the RF power is preferably 12000-16000W, more preferably 13000-15000W, more preferably 14000W; the SiH 4 With NH 3 The flow ratio is preferably 1:2 to 5, more preferably 1:3 to 4, and the pressure is preferably 1500 to 1700 mtorr, more preferably 1550 to 1650 mtorr, and more preferably 1600 mtorr.

[0027] In the process of depositing the second silicon nitride film of the present invention, the temperature is preferably 420-550°C, more preferably 450-520°C, more preferably 480-500°C, and the RF power is preferably 12000-16000W, more preferably 13000-15000W, more preferably 14000W; the SiH 4 With NH 3 The flow ratio is preferably 1:5 to 10, more preferably 1:6 to 9, and more preferably 1:7 to 8. The pressure is preferably 1500 to 1700 mtorr, more preferably 1550 to 1650 mtorr, and more preferably 1600 mtorr.

[0028] In the process of depositing the third silicon nitride film of the present invention, the temperature is preferably 420-550° C., more preferably 450-520° C., more preferably 480-500° C., and the RF power is preferably 15000-18000 W, more preferably 16000-17000 W, more preferably 16500 W; the SiH 4 With NH 3 The flow ratio is preferably 1:5 to 10, more preferably 1:6 to 9, and more preferably 1:7.5 to 8.9. The pressure is preferably 1600 to 1800 mtorr, more preferably 1650 to 1750 mtorr, and more preferably 1700 mtorr.

[0029] In the process of depositing the fourth silicon nitride film of the present invention, the temperature is preferably 420-550° C., more preferably 450-520° C., more preferably 480-500° C., and the RF power is preferably 15000-18000 W, more preferably 16000-17000 W, more preferably 16500 W; the SiH 4 With NH 3 The flow ratio is preferably 1:5 to 15, more preferably 1:8 to 12, and more preferably 1:10 to 11. The pressure is preferably 1600 to 1800 mtorr, more preferably 1650 to 1750 mtorr, and more preferably 1700 mtorr.

[0030] In the process of depositing the fifth silicon oxide film of the present invention, the temperature is preferably 420-550° C., more preferably 450-520° C., more preferably 480-500° C., and the RF power is preferably 10000-15000 W, more preferably 11000-14000 W, more preferably 12000-13000 W; the SiH 4 With N 20The flow ratio is preferably 1:10 to 25, more preferably 1:15 to 20, and more preferably 1:18. The pressure is preferably 1500 to 1700 mtorr, more preferably 1550 to 1650 mtorr, and more preferably 1600 mtorr.

[0031] In the present invention, during the deposition of the underlying silicon nitride film, SiH 4 The flow rate of NH 3 The flow rate is preferably 5000-10000sccm, more preferably 6000-8000sccm, and more preferably 6720-7000sccm; during the deposition of the second silicon nitride film, SiH 4 The flow rate of NH 3 The flow rate is preferably 3000-9000sccm, more preferably 5000-8000sccm, and more preferably 6000-7840sccm. During the deposition of the third silicon nitride film, SiH 4 The flow rate of NH is preferably 500 to 1000 sccm, more preferably 700 to 950 sccm, and more preferably 800 to 920 sccm. 3 The flow rate is preferably 5000-10000sccm, more preferably 7000-9000sccm, and more preferably 8000-8200sccm. During the deposition of the fourth silicon nitride film, SiH 4 The flow rate of NH is preferably 500 to 1000 sccm, more preferably 600 to 900 sccm, and more preferably 750 to 800 sccm. 3 The flow rate is preferably 5000-10000sccm, more preferably 7000-9000sccm, and more preferably 8000-8200sccm. During the deposition of the fifth silicon oxide film, SiH 4 The flow rate is preferably 500 to 1000 sccm, more preferably 600 to 900 sccm, and more preferably 700 to 800 sccm. 20 The flow rate is preferably 5000 to 15000 sccm, more preferably 8000 to 12000 sccm, and even more preferably 10000 to 11000 sccm.

[0032] The back passivation film layer structure of the Topcon solar cell of the present invention is: a bottom layer Sinx-1, a second layer Sinx-2, a third layer Sinx-3, a fourth layer Sinx-4, and a fifth layer Siox-5.

[0033] The present invention also provides a method for preparing the Topcon solar cell back passivation film structure, comprising the following steps:

[0034] A bottom silicon nitride film, a second silicon nitride film, a third silicon nitride film, and a fourth silicon oxide film are sequentially deposited on the back surface of the Topcon solar cell to obtain a back passivation film structure of the Topcon solar cell;

[0035] or sequentially depositing a bottom silicon nitride film, a second silicon nitride film, and a third silicon oxide film on the back surface of a Topcon solar cell to obtain a back passivation film structure of a Topcon solar cell;

[0036] or sequentially depositing a bottom silicon nitride film and a second silicon oxide film on the back surface of a Topcon solar cell to obtain a back passivation film structure of a Topcon solar cell;

[0037] The specific process of depositing each layer of silicon nitride film and the specific process of depositing the oxide film are the same as the process of preparing 4 layers of silicon nitride film and 1 layer of silicon oxide film.

[0038] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0039] Example 1

[0040] PECVD equipment is used to sequentially deposit 4 layers of silicon nitride film and 1 layer of silicon oxide film on the back surface of Topcon solar cells to form a multi-layer back passivation stacked structure. Among them, the thickness of the bottom silicon nitride film is 80nm, and the refractive index is 2.37, the thickness of the second silicon nitride film is 80nm, and the refractive index is 2.15, the thickness of the third silicon nitride film is 40nm, and the refractive index is 2.10, the thickness of the fourth silicon nitride film is 80nm, and the refractive index is 2.00, and the thickness of the fifth silicon oxide film is 20nm, and the refractive index is 1.47.

[0041] During the deposition of the bottom silicon nitride film, the temperature was 500°C, the RF power was 14000W, and SiH 4 With NH 3 , SiH 4 The flow rate is 2400sccm, NH 3 The flow rate is 6720sccm and the pressure is 1600mtorr. During the deposition of the second layer of silicon nitride film, the temperature is 500℃, the RF power is 14000W, and SiH 4 With NH 3 , SiH 4 The flow rate is 1300sccm, NH 3The flow rate is 7840sccm and the pressure is 1600mtorr. During the deposition of the third layer of silicon nitride film, the temperature is 500℃, the RF power is 16500W, and SiH 4 With NH 3 , SiH 4 The flow rate is 920sccm, NH 3 The flow rate is 8200sccm and the pressure is 1700mtorr. During the deposition of the fourth layer of silicon nitride film, the temperature is 500℃, the RF power is 16500W, and SiH 4 With NH 3 , SiH 4 The flow rate is 750sccm, NH 3 The flow rate is 8200sccm and the pressure is 1700mtorr. During the deposition of the fifth silicon oxide film, the temperature is 500℃, the RF power is 12000W, and SiH 4 With N 20 , SiH 4 The flow rate is 600sccm, N 20 The flow rate is 12000sccm and the pressure is 1600mtorr.

[0042] Example 2

[0043] PECVD equipment is used to sequentially deposit 4 layers of silicon nitride film and 1 layer of silicon oxide film on the back surface of Topcon solar cells to form a multi-layer back passivation stacked structure. Among them, the thickness of the bottom silicon nitride film is 50nm, and the refractive index is 2.30, the thickness of the second silicon nitride film is 50nm, and the refractive index is 2.16, the thickness of the third silicon nitride film is 40nm, and the refractive index is 2.15, the thickness of the fourth silicon nitride film is 40nm, and the refractive index is 2.05, and the thickness of the fifth silicon oxide film is 15nm, and the refractive index is 1.48.

[0044] During the deposition of the bottom silicon nitride film, the temperature was 450°C, the RF power was 13000W, and SiH 4 With NH 3 , SiH 4 The flow rate is 2000sccm, NH 3 The flow rate is 6000sccm and the pressure is 1650mtorr. During the deposition of the second layer of silicon nitride film, the temperature is 450℃, the RF power is 13000W, and SiH 4 With NH 3 , SiH 4 The flow rate is 1500sccm, NH 3The flow rate is 8000sccm and the pressure is 1650mtorr. During the deposition of the third layer of silicon nitride film, the temperature is 450℃, the RF power is 16000W, and SiH 4 With NH 3 , SiH 4 The flow rate is 950sccm, NH 3 The flow rate is 8000sccm and the pressure is 1750mtorr. During the deposition of the fourth layer of silicon nitride film, the temperature is 450℃, the RF power is 16000W, and SiH 4 With NH 3 , SiH 4 The flow rate is 600sccm, NH 3 The flow rate is 8000sccm and the pressure is 1750mtorr. During the deposition of the fifth silicon oxide film, the temperature is 450℃, the RF power is 11000W, and SiH 4 With N 20 , SiH 4 The flow rate is 700sccm, N 20 The flow rate is 11000sccm and the pressure is 1650mtorr.

[0045] Example 3

[0046] PECVD equipment is used to sequentially deposit three layers of silicon nitride film and one layer of silicon oxide film on the back surface of Topcon solar cells to form a multi-layer back passivation stacked structure. Among them, the thickness of the bottom silicon nitride film is 70nm, and the refractive index is 2.40, the thickness of the second silicon nitride film is 70nm, and the refractive index is 2.10, the thickness of the third silicon nitride film is 65nm, and the refractive index is 2.10, and the thickness of the fourth silicon oxide film is 20nm, and the refractive index is 1.47.

[0047] During the deposition of the bottom silicon nitride film, the temperature was 480°C, the RF power was 15000W, and SiH 4 With NH 3 , SiH 4 The flow rate is 3000sccm, NH 3 The flow rate is 7000sccm and the pressure is 1550mtorr. During the deposition of the second layer of silicon nitride film, the temperature is 480℃, the RF power is 15000W, and SiH 4 With NH 3 , SiH 4 The flow rate is 1300sccm, NH 3 The flow rate is 9000sccm and the pressure is 1550mtorr. During the deposition of the third layer of silicon nitride film, the temperature is 480℃, the RF power is 17000W, and SiH4 With NH 3 , SiH 4 The flow rate is 1000sccm, NH 3 The flow rate is 9000sccm and the pressure is 1650mtorr. During the deposition of the fourth silicon oxide film, the temperature is 480℃, the RF power is 13000W, and SiH 4 With N 20 , SiH 4 The flow rate is 800sccm, N 20 The flow rate is 13000sccm and the pressure is 1550mtorr.

[0048] Comparative Example 1

[0049] PECVD equipment is used to sequentially deposit three layers of silicon nitride film on the back surface of the Topcon solar cell, omitting the fourth layer of silicon nitride film and the fifth layer of silicon oxide film in Example 1. The refractive index of the third layer of silicon nitride film is 2.05, and other conditions are the same as in Example 1, thereby obtaining a conventional Sinx three-layer film structure.

[0050] The conventional Sinx 3-layer film structure of Comparative Example 1 is: a bottom layer Sinx-1, a second layer Sinx-2, and a third layer Sinx-3.

[0051] The performance test results of the film layer structures of Example 1 and Comparative Example 1 are shown in Table 1.

[0052] Table 1 Performance test results of the film structure of Example 1 and Comparative Example 1

[0053]

[0054] It can be seen from the data in Table 1 that, compared with the conventional film structure, the solar cell back passivation film structure of the present invention has improved electrical properties such as open circuit voltage, short circuit current, series resistance, parallel resistance, fill factor, and cell efficiency, so that the absolute value of the conversion efficiency percentage of the back passivation cell is increased by more than 0.05%.

[0055] The reflectivity comparison diagram of the film structure of Example 1 and Comparative Example 1 is as follows: Figure 1 As shown, Sinx is for comparative example 1, and Sinx / Siox is for example 1. Figure 1 From the reflectivity curve, it can be seen that the back side Sinx / Siox multilayer film structure has a significant advantage over the Sinx film structure in the back side reflectivity range of 800-1000nm.

[0056] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A Topcon solar cell back passivation film structure, characterized in that: The back passivation film layer structure is a multi-layer back passivation stacked structure, which sequentially includes a silicon nitride film and a silicon oxide film; the number of layers of the silicon nitride film is 1 to 4 layers, and the number of layers of the silicon oxide film is 1 layer.

2. The Topcon solar cell back passivation film structure according to claim 1, characterized in that: The back passivation film layer structure sequentially comprises a bottom silicon nitride film, a second silicon nitride film, a third silicon nitride film, a fourth silicon nitride film and a fifth silicon oxide film; the bottom silicon nitride film has a thickness of 40 to 100 nm and a refractive index of 2.20 to 2.40; the second silicon nitride film has a thickness of 30 to 100 nm and a refractive index of 2.10 to 2.20; the third silicon nitride film has a thickness of 30 to 100 nm and a refractive index of 2.10 to 2.20; the fourth silicon nitride film has a thickness of 30 to 100 nm and a refractive index of 2.00 to 2.10; the fifth silicon oxide film has a thickness of 10 to 30 nm and a refractive index of 1.45 to 1.

50.

3. The method for preparing the Topcon solar cell back passivation film structure according to claim 2, characterized in that: The following steps are included: A bottom silicon nitride film, a second silicon nitride film, a third silicon nitride film, a fourth silicon nitride film, and a fifth silicon oxide film are sequentially deposited on the back surface of the Topcon solar cell to obtain a back passivation film structure of the Topcon solar cell.

4. The preparation method according to claim 3, characterized in that: During the deposition of the bottom silicon nitride film, the temperature is 420-550°C, the RF power is 12000-16000W, the flow ratio of SiH4 to NH3 is 1:2-5, and the pressure is 1500-1700mtorr.

5. The preparation method according to claim 3 or 4, characterized in that: During the deposition of the second layer of silicon nitride film, the temperature is 420-550° C., the RF power is 12000-16000 W, the flow ratio of SiH4 to NH3 is 1:5-10, and the pressure is 1500-1700 mtorr.

6. The preparation method according to claim 5, characterized in that: During the deposition of the third layer of silicon nitride film, the temperature is 420-550° C., the RF power is 15000-18000 W, the flow ratio of SiH4 to NH3 is 1:5-10, and the pressure is 1600-1800 mtorr.

7. The preparation method according to claim 6, characterized in that: During the deposition of the fourth silicon nitride film, the temperature is 420-550° C., the RF power is 15000-18000 W, the flow ratio of SiH4 to NH3 is 1:5-15, and the pressure is 1600-1800 mtorr.

8. The preparation method according to claim 7, characterized in that: During the deposition of the fifth silicon oxide film, the temperature is 420-550°C, the RF power is 10000-15000W, and the SiH4 and N 20 The flow ratio is 1:10~25, and the pressure is 1500~1700mtorr.

9. The preparation method according to claim 8, characterized in that: During the deposition of the bottom silicon nitride film, the flow rate of SiH4 is 1000-3000sccm, and the flow rate of NH3 is 5000-10000sccm; during the deposition of the second silicon nitride film, the flow rate of SiH4 is 1000-2000sccm, and the flow rate of NH3 is 3000-9000sccm; during the deposition of the third silicon nitride film, the flow rate of SiH4 is 500-1000sccm, and the flow rate of NH3 is 5000-10000sccm; during the deposition of the fourth silicon nitride film, the flow rate of SiH4 is 500-1000sccm, and the flow rate of NH3 is 5000-10000sccm; during the deposition of the fifth silicon oxide film, the flow rate of SiH4 is 500-1000sccm, and the flow rate of NH3 is 20 The flow rate is 5000~15000sccm.

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