Improved TOPCon back passivation layer growth method

Abstract

The invention discloses an improved TOPCon back surface passivation layer growth method, which comprises a low-pressure chemical vapor deposition method and a plasma enhanced chemical vapor deposition method, and the technical steps of the two methods can be summarized as follows: after texturing, boron diffusion and alkali polishing processes are executed in a TOPCon technology, a laminated Poly structure is manufactured in a Poly process, and then the TOPCon back surface passivation layer is formed. A tunneling oxide layer SiOx of 0.1-2 nm grows on the back surface in the step 1, a bottom layer Poly of more than 30 nm continues to grow in the step 2, a SiOx layer with a certain thickness grows on the basis of the bottom layer Poly in the step 3, a Poly layer continues to grow on the SiOx layer in the step 4, and after a certain thickness is reached, the SiOx layer is formed in the step 5. The step 4 and the step 5 can be executed only once and can also be repeated for multiple times. According to the method, the 1-n layer of SiOx is grown in the Poly layer by adopting a method of introducing the specific gas, and the grown SiOx layer can be used as a barrier layer, a mask or a secondary tunneling layer according to the process optimization requirement, and also can play a role of intermediate passivation.

Description

Technical Field

[0001] The invention relates to the technical field of solar cell Poly, in particular to an improved TOPCon back passivation layer growth method. Background Art

[0002] With the development of the new energy field, TOPCon cells have become one of the photovoltaic energy sources with the highest mass production conversion efficiency and the greatest potential. Its core processes are the tunneling layer and polysilicon growth. If the core processes can be further optimized, the core competitiveness of TOPCon cells will be greatly enhanced.

[0003] At present, there is only one tunnel layer and one polysilicon layer, and the number of tunnel layers is small, which makes it difficult to magnify the advantages of this technology. Summary of the invention

[0004] The object of the present invention is to provide an improved TOPCon back passivation layer growth method to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions: an improved TOPCon back passivation layer growth method, including a low-pressure chemical vapor deposition method and a plasma enhanced chemical vapor deposition method;

[0006] The low pressure chemical vapor deposition method comprises the following steps:

[0007] S11, the alkaline polished cell is heated to 500-700°C, and 30000-40000sccm of oxygen is passed through to grow a 0.1-2nm tunnel oxide layer SiOx on the back of the cell;

[0008] S12, at a temperature of 500-700°C, remove oxygen, and pass 200-800sccm of silane gas to grow a bottom layer Poly of more than 30nm;

[0009] S13, at a temperature of 500-700°C, remove silane, pass 30000-40000sccm of oxygen, and oxygen and silicon react to generate SiOx of a certain thickness;

[0010] S14, at a temperature of 500-700°C, remove oxygen, and pass 200-800sccm of silane gas to grow a certain thickness of Poly;

[0011] S15, at a temperature of 500-700°C, remove silane, pass 30000-40000sccm of oxygen, and oxygen and silicon react to generate SiOx of a certain thickness;

[0012] S16, repeat: Step S14 and step S15 can be performed once or multiple times;

[0013] The plasma enhanced chemical vapor deposition method comprises the following steps:

[0014] S21, the cell after alkaline polishing is heated to 200-600°C, and 5000-20000sccm of nitrous oxide gas is passed to grow a 0.1-2nm tunneling oxide layer SiOx on the back of the cell;

[0015] S22, at a temperature of 200-600° C., remove the nitrous oxide, and pass a mixed gas of 3000-4000 sccm silane, 100-1000 sccm phosphine, and 2000-20000 sccm hydrogen to grow a bottom layer Poly of more than 30 nm;

[0016] S23, at a temperature of 200-600°C, remove the mixed gas, pass 5000-20000sccm of nitrous oxide gas, and generate SiOx of a certain thickness;

[0017] S24, at a temperature of 200-600° C., remove the nitrous oxide, and pass a mixed gas of 3000-4000 sccm silane, 100-1000 sccm phosphine, and 2000-20000 sccm hydrogen to grow a Poly with a certain thickness;

[0018] S25, at a temperature of 200-600°C, remove the mixed gas, pass 5000-20000sccm of nitrous oxide gas, and generate SiOx of a certain thickness;

[0019] S26. Repeat: Step S24 and step S25 may be performed once or multiple times.

[0020] Preferably, the SiOx in the Poly layer has 1-n layers.

[0021] Preferably, the SiOx generated in the Poly layer includes conventional suede, silicon substrate, SiOx layer one, Poly layer one, a layer of SiOx grown in the Poly layer, Poly layer two, and SiOx layer two, and the conventional suede, silicon substrate, SiOx layer one, Poly layer one, a layer of SiOx grown in the Poly layer, Poly layer two, and SiOx layer two are arranged in sequence from top to bottom.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] During the growth of the Poly layer, a method of passing a specific gas is used to grow 1-n layers of SiOx in the Poly layer. The grown SiOx layer can be used as a barrier layer, mask or secondary tunneling layer according to the needs of process optimization, and can also play a role of intermediate passivation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the present invention.

[0025] In the figure: 1. Conventional velvet; 2. Silicon substrate; 3. SiOx layer 1; 4. Poly layer 1; 5. 1 layer of SiOx grown in the Poly layer; 6. Poly layer 2; 7. SiOx layer 2. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0027] See also Figure 1 , the present invention provides a technical solution: an improved TOPCon back passivation layer growth method, including a low-pressure chemical vapor deposition method and a plasma enhanced chemical vapor deposition method;

[0028] The low pressure chemical vapor deposition method comprises the following steps:

[0029] S11, the alkaline polished cell is heated to 500-700°C, and 30000-40000sccm of oxygen is passed through to grow a 0.1-2nm tunnel oxide layer SiOx on the back of the cell;

[0030] S12, at a temperature of 500-700°C, remove oxygen, and pass 200-800sccm of silane gas to grow a bottom layer Poly of more than 30nm;

[0031] S13, at a temperature of 500-700°C, remove silane, pass 30000-40000sccm of oxygen, and oxygen and silicon react to generate SiOx of a certain thickness;

[0032] S14, at a temperature of 500-700°C, remove oxygen, and pass 200-800sccm of silane gas to grow a certain thickness of Poly;

[0033] S15, at a temperature of 500-700°C, remove silane, pass 30000-40000sccm of oxygen, and oxygen and silicon react to generate SiOx of a certain thickness;

[0034] S16, repeat: Step S14 and step S15 can be performed once or multiple times;

[0035] The plasma enhanced chemical vapor deposition method comprises the following steps:

[0036] S21, the cell after alkaline polishing is heated to 200-600°C, and 5000-20000sccm of nitrous oxide gas is passed to grow a 0.1-2nm tunneling oxide layer SiOx on the back of the cell;

[0037] S22, at a temperature of 200-600° C., remove the nitrous oxide, and pass a mixed gas of 3000-4000 sccm silane, 100-1000 sccm phosphine, and 2000-20000 sccm hydrogen to grow a bottom layer Poly of more than 30 nm;

[0038] S23, at a temperature of 200-600°C, remove the mixed gas, pass 5000-20000sccm of nitrous oxide gas, and generate SiOx of a certain thickness;

[0039] S24, at a temperature of 200-600° C., remove the nitrous oxide, and pass a mixed gas of 3000-4000 sccm silane, 100-1000 sccm phosphine, and 2000-20000 sccm hydrogen to grow a Poly with a certain thickness;

[0040] S25, at a temperature of 200-600°C, remove the mixed gas, pass 5000-20000sccm of nitrous oxide gas, and generate SiOx of a certain thickness;

[0041] S26. Repeat: Step S24 and step S25 may be performed once or multiple times.

[0042] In the present invention, the SiOx in the Poly layer has 1-n layers.

[0043] In the present invention, the SiOx generated in the Poly layer includes a conventional velvet surface 1, a silicon substrate 2, a SiOx layer 3, a Poly layer 4, a layer of SiOx 5 grown in the Poly layer, a Poly layer 6, and a SiOx layer 7, and the conventional velvet surface 1, the silicon substrate 2, the SiOx layer 3, the Poly layer 4, a layer of SiOx 5 grown in the Poly layer, a Poly layer 6, and a SiOx layer 7 are arranged in sequence from top to bottom.

[0044] The present invention adopts a method of adjusting the temperature and gas during the growth of the Poly layer to grow 1-n layers of SiOx in the Poly layer. Its functions are divided into four aspects: first, it can be used as a diffusion barrier layer to control the diffusion rate of phosphorus; second, it can be used as a mask to make the Poly layer more uniform; third, the SiOx layer can be controlled within a certain thickness range to effectively absorb electrons as a secondary tunneling layer; and fourth, it plays a role of intermediate passivation.

[0045] The 1-n SiOx layers made in the Poly layer by the method of the present invention can be used as a diffusion barrier layer to control the diffusion speed of phosphorus atoms, can be used as a mask to make the Poly layer more uniform, can be used as a secondary tunneling layer to effectively absorb electrons within a certain thickness range, and can also play a role of intermediate passivation. The scheme of the present invention is: after performing the texturing, boron diffusion, and alkali polishing processes in the TOPCon technology, a laminated Poly structure is made in the Poly process, step 1 grows a 0.1-2nm tunneling oxide layer SiOx on the back, step 2 continues to grow a bottom Poly of more than 30nm, step 3 grows a SiOx layer of a certain thickness on the basis of the bottom Poly, step 4 continues to grow a Poly layer on the SiOx layer, and after reaching a certain thickness, step 5 forms a SiOx layer. Steps 4 and 5 can be performed only once or repeated multiple times.

[0046] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in the field. Although the embodiments of the present invention have been shown and described, it is understood by ordinary technicians in the field that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. An improved TOPCon back passivation layer growth method, characterized in that: Including low pressure chemical vapor deposition method and plasma enhanced chemical vapor deposition method; The low pressure chemical vapor deposition method comprises the following steps: S11, the alkaline polished cell is heated to 500-700°C, and 30000-40000sccm of oxygen is passed through to grow a 0.1-2nm tunnel oxide layer SiOx on the back of the cell; S12, at a temperature of 500-700°C, remove oxygen, and pass 200-800sccm of silane gas to grow a bottom layer Poly of more than 30nm; S13, at a temperature of 500-700°C, remove silane, pass 30000-40000sccm of oxygen, and oxygen and silicon react to generate SiOx of a certain thickness; S14, at a temperature of 500-700°C, remove oxygen, and pass 200-800sccm of silane gas to grow a certain thickness of Poly; S15, at a temperature of 500-700°C, remove silane, pass 30000-40000sccm of oxygen, and oxygen and silicon react to generate SiOx of a certain thickness; S16, repeat: Step S14 and step S15 can be performed once or multiple times; The plasma enhanced chemical vapor deposition method comprises the following steps: S21, the cell after alkaline polishing is heated to 200-600°C, and 5000-20000sccm of nitrous oxide gas is passed to grow a 0.1-2nm tunneling oxide layer SiOx on the back of the cell; S22, at a temperature of 200-600° C., remove the nitrous oxide, and pass a mixed gas of 3000-4000 sccm silane, 100-1000 sccm phosphine, and 2000-20000 sccm hydrogen to grow a bottom layer Poly of more than 30 nm; S23, at a temperature of 200-600°C, remove the mixed gas, pass 5000-20000sccm of nitrous oxide gas, and generate SiOx of a certain thickness; S24, at a temperature of 200-600° C., remove the nitrous oxide, and pass a mixed gas of 3000-4000 sccm silane, 100-1000 sccm phosphine, and 2000-20000 sccm hydrogen to grow a Poly with a certain thickness; S25, at a temperature of 200-600°C, remove the mixed gas, pass 5000-20000sccm of nitrous oxide gas, and generate SiOx of a certain thickness; S26. Repeat: Step S24 and step S25 may be performed once or multiple times.

2. The improved TOPCon back passivation layer growth method according to claim 1, characterized in that: The SiOx in the Poly layer has 1-n layers.

3. The improved TOPCon back passivation layer growth method according to claim 2, characterized in that: The SiOx generated in the Poly layer comprises a conventional velvet surface (1), a silicon substrate (2), a SiOx layer 1 (3), a Poly layer 1 (4), a SiOx layer (5) grown in the Poly layer, a Poly layer 2 (6), and a SiOx layer 2 (7), and the conventional velvet surface (1), the silicon substrate (2), the SiOx layer 1 (3), the Poly layer 1 (4), a SiOx layer (5) grown in the Poly layer, a Poly layer 2 (6), and a SiOx layer 2 (7) are arranged in sequence from top to bottom.

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