CN117038797A

CN117038797A - Solar cell manufacturing method and solar cell

Info

Publication number: CN117038797A
Application number: CN202311216010.4A
Authority: CN
Inventors: 徐家萌
Original assignee: Anhui Jinko Energy Co ltd
Current assignee: Anhui Jinko Energy Co ltd
Priority date: 2023-09-19
Filing date: 2023-09-19
Publication date: 2023-11-10

Abstract

The embodiment of the disclosure relates to the field of photovoltaics, and provides a manufacturing method of a solar cell and the solar cell, wherein the manufacturing method of the solar cell comprises the following steps: providing a substrate; forming a tunneling layer; forming a semiconductor layer; and performing doping treatment to convert the semiconductor layer into a doped conductive layer, wherein the doping treatment comprises: the method comprises a deposition step, a heating step, a pushing step, at least one expansion supplementing step and a cooling step which are sequentially carried out; the deposition step is used for forming a doping source layer; the heating step is used for heating; a step of advancing, for diffusing the doped ions into the semiconductor layer; and a complementary diffusion step for diffusing the counter-doped ions into the semiconductor layer, wherein the complementary diffusion step comprises the following steps: a cooling stage for reducing the process temperature of the doping treatment by a preset temperature and a diffusion stage for diffusing the doping ions into the semiconductor layer; the cooling step is used for reducing the process temperature of the doping treatment to the target temperature. The performance of the formed solar cell can be improved.

Description

Solar cell manufacturing method and solar cell

Technical Field

The embodiment of the disclosure relates to the field of photovoltaics, in particular to a manufacturing method of a solar cell and the solar cell.

Background

The fossil energy has the advantages of air pollution and limited reserves, and solar energy has the advantages of cleanness, no pollution, abundant resources and the like, so the solar energy is gradually becoming a core clean energy for replacing the fossil energy, and the solar cell becomes the development center of gravity for the utilization of the clean energy due to the good photoelectric conversion efficiency of the solar cell.

Solar cells are used to convert solar energy into electric energy, and thus, solar cells are widely used. Solar cells can be classified into crystalline silicon cells and thin film cells, wherein in crystalline silicon cells, tunnel oxide passivation contact structure cells are favored because of their higher theoretical efficiency, and therefore, it is necessary to study tunnel oxide passivation contact structure cells with better performance.

Disclosure of Invention

The embodiment of the disclosure provides a manufacturing method of a solar cell and the solar cell, which can at least improve the performance of the formed solar cell.

According to some embodiments of the present disclosure, an aspect of embodiments of the present disclosure provides a method for manufacturing a solar cell, including: providing a substrate comprising opposing first and second faces; forming a tunneling layer, wherein the tunneling layer covers the second surface of the substrate; forming a semiconductor layer, wherein the semiconductor layer covers the surface of the tunneling layer away from the second face; performing doping treatment to diffuse doping ions into the semiconductor layer and convert the semiconductor layer into a doped conductive layer, wherein the doping treatment comprises: the method comprises a deposition step, a heating step, a pushing step, at least one expansion supplementing step and a cooling step which are sequentially carried out; the deposition step is used for forming a doped source layer on the semiconductor layer, wherein the doped source layer is doped with the doped ions; the heating step is used for heating the process temperature of the doping treatment to the doping temperature; the pushing step is used for keeping the process temperature of the doping treatment to be the doping temperature within a preset duration so as to diffuse the doping ions into the semiconductor layer; the at least one complementary diffusion step is used for diffusing the doped ions into the semiconductor layer, and the complementary diffusion step comprises the following steps: the temperature reduction stage is used for reducing the process temperature of the doping treatment by a preset temperature, and the diffusion stage is used for diffusing the doping ions into the semiconductor layer at the process temperature after the temperature reduction stage is used for reducing the temperature; the cooling step is used for reducing the process temperature of the doping treatment to the target temperature.

In some embodiments, the process parameters of the diffusion phase include: the process temperature is 800-850 ℃, the process time is 100-140 s, the gas flow of the introduced nitrogen is 800-1200sccm, and the gas flow of the introduced oxygen is 400-800sccm.

In some embodiments, the number of the complementary diffusion steps is greater than 1, and the process time period of the last diffusion stage is greater than the process time period of the previous diffusion stage.

In some embodiments, the process duration of each diffusion stage is 180s or less.

In some embodiments, the step of compensating further comprises a source-on stage, after the step of reducing the temperature and before the step of diffusing, for forming a doped sub-layer on the doped source layer, the doped sub-layer being doped with the dopant ions.

In some embodiments, the number of the complementary expansion steps is greater than 1, and the thickness of the doped sub-layer formed in the last through-source stage is smaller than the thickness of the doped sub-layer formed in the previous through-source stage in the direction perpendicular to the first surface.

In some embodiments, the number of the complementary expansion steps is greater than 1, and the doping concentration of the doping ions in the doping sub-layer formed in the last through-source stage is smaller than the doping concentration of the doping ions in the doping sub-layer formed in the previous through-source stage.

In some embodiments, the expanding step further includes a pumping stage for reducing the process gas pressure of the doping process to a preset gas pressure after the cooling stage and before the diffusing stage.

In some embodiments, the predetermined air pressure is 150-250pa.

In some embodiments, the doping concentration of the doping ions in the doped conductive layer is 1e 20-1 e21atoms/cm3.

In some embodiments, the number of the expansion steps is greater than 1, and the reduced temperature is the same each time the temperature reduction stage.

According to some embodiments of the present disclosure, another aspect of embodiments of the present disclosure also provides a solar cell, which may be formed by a method for manufacturing the solar cell.

The technical scheme provided by the embodiment of the disclosure has at least the following advantages: forming a tunneling layer by providing a substrate, forming a semiconductor layer, and performing doping treatment to form a solar cell, wherein the doping treatment comprises: the method comprises a deposition step, a heating step, a pushing step, at least one complementary expansion step and a cooling step which are sequentially carried out, wherein the deposition step is used for forming a doped source layer, the heating step is used for providing the process temperature of the pushing step, the pushing step is used for diffusing doped ions in the doped source layer into a semiconductor layer, and the at least one complementary expansion step is used for carrying out secondary diffusion into the semiconductor layer, so that the doped conductive layer can be subjected to complementary diffusion, the field passivation effect of the solar cell is optimized, the problem of the reduction of the doping concentration on the surface of the doped conductive layer caused by high-temperature pushing can be solved, and the performance of the formed solar cell is improved.

Drawings

One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, which are not to be construed as limiting the embodiments unless specifically indicated otherwise; in order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the conventional technology, the drawings required for the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present disclosure, and other drawings may be obtained according to these drawings without inventive effort to those of ordinary skill in the art.

Fig. 1 to 5 are schematic structural diagrams corresponding to steps of a method for manufacturing a solar cell according to an embodiment of the disclosure;

fig. 6 to 8 are schematic structural diagrams corresponding to each step of a method for manufacturing a second solar cell according to an embodiment of the disclosure;

fig. 9 is a temperature change chart of a first method for manufacturing a solar cell according to an embodiment of the disclosure;

fig. 10 is a temperature change chart of a second method for manufacturing a solar cell according to an embodiment of the disclosure.

Detailed Description

As known from the background art, in the current high temperature process, the doped ions on the surface of the doped conductive layer diffuse towards the direction close to the substrate, which results in the reduction of the doping concentration on the surface of the doped conductive layer, and affects the performance of the solar cell.

The embodiment of the disclosure provides a method for manufacturing a solar cell, which comprises the steps of providing a substrate, forming a tunneling layer, forming a semiconductor layer and performing doping treatment to form the solar cell, wherein the doping treatment comprises the following steps: the method comprises a deposition step, a heating step, a pushing step, at least one complementary expansion step and a cooling step which are sequentially carried out, wherein the deposition step is used for forming a doped source layer, the heating step is used for providing the process temperature of the pushing step, the pushing step is used for diffusing doped ions in the doped source layer into a semiconductor layer, and the at least one complementary expansion step is used for carrying out secondary diffusion into the semiconductor layer, so that the doped conductive layer can be subjected to complementary diffusion, the field passivation effect of the solar cell is optimized, the problem of the reduction of the doping concentration on the surface of the doped conductive layer caused by high-temperature pushing can be solved, and the performance of the formed solar cell is improved.

Embodiments of the present disclosure will be described in detail below with reference to the attached drawings. However, those of ordinary skill in the art will understand that in the various embodiments of the present disclosure, numerous technical details have been set forth in order to provide a better understanding of the present disclosure. However, the technical solutions claimed in the present disclosure can be implemented without these technical details and with various changes and modifications based on the following embodiments.

Referring to fig. 1 to 5 and fig. 9, fig. 1 to 5 are schematic structural diagrams corresponding to steps of a method for manufacturing a solar cell according to an embodiment of the disclosure, and fig. 9 is a temperature change chart of a method for manufacturing a first solar cell according to an embodiment of the disclosure.

In some embodiments, a method of fabricating a solar cell may include: a substrate 100 is provided, the substrate 100 comprising opposing first and second faces 110, 120.

The manufacturing method of the solar cell may further include: a tunneling layer 101 is formed, the tunneling layer 101 covering the second side 120 of the substrate 100.

The manufacturing method of the solar cell may further include: the semiconductor layer 102 is formed, and the semiconductor layer 102 covers a surface of the tunneling layer 101 remote from the second face 120.

The manufacturing method of the solar cell may further include: a doping process is performed to diffuse doping ions into the semiconductor layer 102 to convert the semiconductor layer 102 into a doped conductive layer 103, wherein the doping process includes: the method comprises a deposition step, a heating step, a pushing step, at least one expansion supplementing step and a cooling step which are sequentially carried out; the deposition step is used to form a doped source layer 104 on the semiconductor layer 102, where the doped source layer 104 is doped with doping ions; the heating step is used for heating the process temperature of the doping treatment to the doping temperature; a step of advancing, wherein the process temperature of the doping treatment is kept at a doping temperature within a preset period of time, so that the doping ions diffuse into the semiconductor layer 102; at least one complementary diffusion step for diffusing the counter dopant ions into the doped conductive layer 103, the complementary diffusion step including: a cooling stage for reducing the process temperature of the doping treatment by a preset temperature and a diffusion stage for diffusing the doping ions into the doped conductive layer 103 at the process temperature after the cooling stage; the cooling step is used for reducing the process temperature of the doping treatment to the target temperature.

The disclosed embodiments provide a method for manufacturing a solar cell, which includes providing a substrate 100, forming a tunneling layer 101, forming a semiconductor layer 102, and performing doping treatment to form the solar cell, wherein the doping treatment includes: the deposition step, the heating step, the pushing step, the at least one complementary expansion step and the cooling step are sequentially performed, the deposition step is used for forming a doped source layer, the heating step is used for providing the process temperature of the pushing step, the pushing step is used for diffusing doped ions in the doped source layer into the semiconductor layer 102, the at least one complementary expansion step is used for conducting secondary diffusion into the semiconductor layer 102, so that the doped conductive layer 103 can be subjected to complementary diffusion, the field passivation effect of the solar cell is optimized, the problem of the reduction of the doping concentration on the surface of the doped conductive layer 103 caused by high-temperature pushing can be solved, the performance of the formed solar cell is improved, the process temperature of the whole solar cell manufacturing method can be reduced through the cooling step, and the solar cell can be taken out conveniently and the follow-up step is performed.

Referring to fig. 1, in some embodiments, a substrate 100 may be a semiconductor base, such as silicon, germanium, silicon germanium, or silicon on insulator. The material of the substrate 100 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, which may be silicon or germanium, for example. The elemental semiconductor material may be in a single crystal state, a polycrystalline state, an amorphous state, or a microcrystalline state (a state having both a single crystal state and an amorphous state, referred to as a microcrystalline state), and for example, silicon may be at least one of single crystal silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon. The material of the substrate 100 may also be a compound semiconductor material. For example, the material of the substrate 100 may be silicon carbide, an organic material, or a multi-component compound.

In some embodiments, the substrate 100 may be an N-type semiconductor base or a P-type semiconductor base. The N-type semiconductor substrate is doped with an N-type doping element, which may be any of v group elements such As phosphorus (P) element, bismuth (Bi) element, antimony (Sb) element, and arsenic (As) element. The P-type semiconductor substrate is doped with a P-type element, and the P-type doped element may be any one of group iii elements such as boron (B) element, aluminum (Al) element, gallium (Ga) element, and indium (In) element.

In some embodiments, the solar cell is a single-sided cell, and the first side 110 of the substrate 100 may be a light receiving surface for receiving incident light, and the second side 120 may be a backlight surface. In some embodiments, the solar cell is a double sided cell, and both the first side 110 and the second side 120 of the substrate 100 can be used as light receiving surfaces for receiving incident light.

In some embodiments, a texturing process may be further performed on at least one surface of the first surface 110 or the second surface 120 of the substrate 100 before forming the dopant source layer 104, so as to form a textured surface on at least one surface of the first surface 110 or the second surface 120 of the substrate 100, so that the absorption and utilization rate of the first surface 110 and the second surface 120 of the substrate 100 on incident light may be enhanced. In some embodiments, the texture may be a pyramid texture, which is a common texture, not only reduces the reflectivity of the surface of the substrate 100, but also forms light traps, which increases the absorption effect of the substrate 100 on incident light, and increases the conversion efficiency of the solar cell.

Specifically, if the solar cell is a single-sided cell, a textured surface may be formed on the light receiving surface of the substrate 100, for example, may be a pyramid textured surface, and the back surface of the substrate may be a polished surface, i.e., the back surface of the substrate 100 is flatter than the light receiving surface. In the case of a single-sided battery, a textured surface may be formed on both the light-receiving surface and the back surface of the substrate 100.

If the solar cell is a double-sided cell, a textured surface may be formed on both the light-receiving surface and the back surface of the substrate 100.

Referring to fig. 2, a tunneling layer 101, a semiconductor layer 102, and a dopant source layer 104 are formed.

Referring to fig. 3, a step of advancing is performed to convert the semiconductor layer 102 into the initially doped layer 113.

Referring to fig. 4 and 5, a complementary expansion step is performed to form a complementary expansion step to convert the initially doped layer 113 into the doped conductive layer 103.

The doping element concentration in the doped conductive layer 103 is greater than the doping element concentration of the substrate 100 to form a sufficiently high barrier on the second side 120 of the substrate 100 that can induce bending of the energy band of the second side 120 of the substrate 100, enabling accumulation of multiple (also known as majority carriers) and depletion of fewer (also known as minority carriers) of the second side 120 of the substrate 100, reducing carrier recombination at the second side 120 of the substrate 100. The tunneling layer 101 may asymmetrically shift the energy band of the second side 120 of the substrate 100, such that the potential barrier to multiple carriers in the carriers is lower than the potential barrier to fewer carriers in the carriers, and thus multiple carriers may more easily quantum tunnel through the tunneling layer 101 for transmission into the doped conductive layer 103, while fewer carriers may be more difficult to pass through the tunneling layer 101 for selective transmission of carriers. In addition, the tunneling layer 101 also has a chemical passivation effect. Specifically, since the interface between the substrate 100 and the tunneling layer 101 has an interface state defect, the interface state density of the second surface of the substrate 100 is relatively high, and the increase of the interface state density can promote the recombination of photo-generated carriers, reduce the filling factor, the short-circuit current and the open-circuit voltage of the solar cell, and further make the photoelectric conversion efficiency of the solar cell relatively low.

The tunneling layer 101 is disposed on the second surface 120 of the substrate 100, so that the tunneling layer 101 has a chemical passivation effect on the second surface 120 of the substrate 100, specifically: by saturating dangling bonds on the second side 120 of the substrate 100, the density of defect states on the second side 120 of the substrate 100 is reduced, reducing recombination centers on the surface of the substrate 100 to reduce the carrier recombination rate.

In some embodiments, the material of the tunneling layer 101 may include at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or magnesium fluoride.

The doped conductive layer 103 also acts as a field passivation effect. Specifically, the doped conductive layer 103 forms an electrostatic field on the second surface 120 of the substrate 100, which points to the inside of the substrate 100, so that minority carriers escape from the interface, thereby reducing minority carrier concentration, reducing carrier recombination rate at the interface of the substrate 100, increasing open-circuit voltage, short-circuit current and filling factor of the solar cell, and improving photoelectric conversion efficiency of the solar cell.

The material of the doped conductive layer 103 may include at least one of amorphous silicon, polysilicon, or silicon carbide.

The doped conductive layer 103 may be doped with the same type of doping element as the substrate 100, for example, the doped element type of the substrate is P-type, and the doped element type in the doped conductive layer 103 may be P-type; the doping element type of the substrate is N-type, and the doping element type in the doped conductive layer 103 may be N-type.

As can be seen, the passivation contact structure provides good surface passivation for the second surface 120 of the substrate 100, and the tunneling layer 101 can make majority carriers tunnel into the doped conductive layer 103 while blocking minority carrier recombination, so that the majority carriers are laterally transferred to the doped conductive layer 103 and collected by the metal electrode, thereby greatly reducing metal contact recombination current and improving open-circuit voltage and short-circuit current of the solar cell.

The type of dopant ions in the dopant source layer 104 is selected according to the desired dopant conductive layer 103, for example, the dopant conductive layer 103 needs to be P-type doped, and the type of dopant ions in the dopant source layer 104 may be P-type ions.

In some embodiments, prior to performing the depositing step, further comprising: and a boat feeding step, wherein the technological parameters of the boat feeding step comprise: the process time is 50-200s, the process temperature is 760-790 ℃, the gas flow of the nitrogen is 500-2000sccm, the boat entering step is actually a preheating step before the doping ions are diffused into the semiconductor layer 102, impurity gas in the process environment of doping treatment can be cleaned, the reliability of the manufacturing method of the whole solar cell is improved, and the nitrogen can circulate in the cavity by introducing the nitrogen and can uniformly diffuse heat into the cavity.

The chamber here refers to a space in the furnace body in which the reactant gas, the substrate 100, and the like are contained in the furnace body in which the doping process is performed later.

In some embodiments, after the step of advancing the boat may further include: the process parameters of the vacuumizing step comprise: the process time is 60-300s, the process temperature is 760-790 ℃, and the gas in the whole cavity can be pumped away through the vacuumizing step, so that the good process environment in the cavity is ensured.

In some embodiments, the step of evacuating may further comprise: the leak detection step comprises the following steps of: the process time is 50-100s, the process temperature is 760-790 ℃, and the air leakage condition in the cavity can be checked through the leakage detection step, so that the reliability of the manufacturing method of the whole solar cell is improved.

In some embodiments, the leak detection step may further include, after: the impurity removing step, the process steps of the impurity removing step may include: the process time is 200-400s, the process temperature is 760-790 ℃, the gas flow of the introduced nitrogen is 1500-3000sccm, and impurities in the cavity can be purged completely through the impurity removal step, so that the manufacturing method of the solar cell has a good process environment.

In some embodiments, a pre-oxidation step may also be performed after the impurity removal step, by which a portion of the semiconductor layer 102 may be converted to an oxide layer, the process parameters of the pre-oxidation step may include: the process time is 200-400s, the process temperature is 790-810 ℃, the gas flow of the introduced nitrogen is 1000-2000sccm, and the gas flow of the introduced oxygen is 500-1500sccm. The semiconductor layer 102 partially located on top may be oxidized by an oxidation step, and it may be appreciated that the material of the oxide layer is more compatible with the subsequently formed dopant source layer 104 than the material of the semiconductor layer 102, so that the dopant ions in the dopant source layer 104 may be conveniently diffused into the semiconductor layer 102.

In some embodiments, a pre-heat step may also be performed prior to the deposition step, by which the process temperature of the deposition process may be raised to the process temperature required for the deposition step.

In some embodiments, the semiconductor layer 102 may be formed after the boat-carrying step, the vacuum-pumping step, the leak detection step, the impurity removal step, or a partial step of the pre-oxidation step, or the doping treatment may be directly performed after the semiconductor layer 102 is formed.

In some embodiments, the process parameters of the depositing step may include: the process time is 500-1500s, the process temperature is 790-810 ℃, the gas flow rate of the introduced nitrogen is 1000-3000sccm, the gas flow rate of the introduced oxygen is 100-800sccm, and the gas carrying the deposition material is also introduced in 1000-3000sccm, that is, the deposition material of the doped source layer 104 is carried into the chamber by introducing the gas carrying the deposition material in 1000-3000sccm, and then deposited on the surface of the semiconductor layer 102.

In some embodiments, the heating step may sweep the surface of the doped source layer 104 by introducing a gas while heating, and by adopting a manner of heating and sweeping, the surface temperature of the doped source layer 104 may be more uniform, and the reliability of the manufacturing method of the solar cell may be improved.

In some embodiments, the doping temperature may be 880-930 ℃, such as 890 ℃, 900 ℃, 910 ℃, or 920 ℃. The doping temperature of the heating step is 880-930 ℃, so that a temperature basis is provided for the subsequent advancing step.

In some embodiments, the process parameters of the warming step may further include: the process time is 500-1000s, the gas flow of the introduced nitrogen is 1000-3000sccm, the gas flow of the introduced oxygen is 300-1000sccm, and the air pressure in the cavity is 150-200 pa.

In some embodiments, oxygen is continuously introduced during the diffusion process in the advancing step, taking doped ions as phosphorus as an example, the material of the doped source layer may be phosphorus oxychloride, in the first heating step, part of phosphorus oxychloride is thermally decomposed to generate phosphorus pentachloride, and the phosphorus pentachloride corrodes the substrate 100, so that oxygen is also introduced during the first heating step, on one hand, the oxygen reacts with the phosphorus pentachloride to generate phosphorus pentoxide, so as to avoid damaging the substrate 100, and on the other hand, the oxygen also oxidizes part of the semiconductor layer to generate an oxide layer, and the oxide layer reacts with the phosphorus pentachloride to generate elemental phosphorus, so that the semiconductor layer is doped.

In some embodiments, the oxygen gas flow rate of the pushing step is 1000sccm-3000sccm, such as 1500sccm, 1800sccm, 2000sccm, 2500sccm, 2800sccm, or the like. It can be understood that the pushing step is the main doping step in the doping treatment, so that the pushing step has a better doping effect by setting the gas flow of the oxygen introduced in the pushing step to be 1000sccm-3000 sccm.

If the flow rate of the oxygen gas introduced in the pushing step is less than 1000sccm, on the one hand, the effect of oxidizing phosphorus pentachloride is poor, and the effect of doping the semiconductor layer in the subsequent step is poor; if the flow rate of the oxygen gas introduced in the advancing step is more than 3000sccm, the rate of oxidizing the semiconductor layer is too high, and an excessive oxide layer is formed.

In some embodiments, the predetermined duration of the advancing step is 200s-800s, such as 200s, 360s, 450s, 600s, 750s, or the like. By setting the preset duration of the advancing step to be 200s-800s, the advancing step can have a certain doping effect and simultaneously avoid the diffusion of doping ions into the substrate 100, so that the reliability of the formed solar cell can be improved.

If the preset duration of the advancing step is less than 200s, in the advancing step, the concentration of the doped ions diffused into the semiconductor layer 102 is not high, so that the doping effect in the semiconductor layer 102 is poor and the performance of the solar cell is affected; if the predetermined time period of the advancing step is longer than 800s, then part of the dopant ions will diffuse into the substrate 100 during the advancing step, affecting the performance of the tunneling layer 101.

In some embodiments, the process parameters of the advancing step may further include: the flow rate of the introduced nitrogen is 1000-3000sccm, and the air pressure in the cavity is controlled to be 550-650 pa.

It will be appreciated that as the advancing step proceeds, at least a portion of the dopant ions in the dopant source layer 104 diffuse into the semiconductor layer 102 and form an initial doped layer 113, the remaining dopant source layer 104 being the first functional layer 106, the dopant concentration of the dopant ions in the first functional layer 106 being less than the dopant concentration in the dopant source layer 104.

It should be noted that, as the advancing step proceeds, the doped ions in the portion of the initially doped layer 113 away from the substrate 100 diffuse toward the direction toward the substrate 100, which results in that the doped concentration of the doped ions in the portion of the initially doped layer 113 away from the substrate 100 is smaller than the doped concentration of the doped ions in the portion toward the substrate 100, so that the embodiment of the present disclosure further performs the complementary expanding step to dope the portion of the initially doped layer 113 away from the substrate 100.

In some embodiments, the cooling stage in the complementary diffusion step is used to reduce the process temperature of the doping treatment, so that the subsequent cooling treatment can be facilitated, the process duration of the cooling treatment is reduced, the diffusion stage is used to perform complementary diffusion on the initially doped layer 113, in the advancing step, as the advancing step proceeds, the doped ions in the initially doped layer 113 diffuse toward the direction close to the substrate 100, so that the concentration of the doped ions on the surface of the initially doped layer 113 away from the substrate 100 is reduced, and the doped ions in the doped source layer can be further diffused into the initially doped layer 113 through the complementary diffusion step to form the doped conductive layer 103.

In some embodiments, the number of make-up steps is greater than 1, and the temperature decrease is the same for each cool-down stage. The temperature reduced in each cooling stage is the same, so that the technological parameters in each cooling stage are the same, and the technological difficulty of the whole solar cell is reduced.

It should be noted that the temperature reduced in each cooling stage is the same, or the process parameters of each cooling stage are different, for example, the temperature reduced in each cooling stage is the same by increasing the duration of the cooling stage and reducing the flow of the gas introduced in the cooling stage.

In some embodiments, the preset temperature reduced during the cool down stage is between 30 and 50 ℃. It will be appreciated that if the preset temperature of each decrease in the cooling stage is less than 30 ℃, the temperature of each decrease in the cooling stage is lower, which may cause the dopant ions to continue to diffuse toward the direction close to the substrate 100, resulting in the decrease in the concentration of the dopant ions on the surface of the doped conductive layer 103 away from the substrate 100, and if the preset temperature of each decrease in the cooling stage is greater than 50 ℃, the temperature of each decrease in the cooling stage is higher, resulting in the process temperature during the diffusion stage being lower, resulting in poor doping effect of the doped conductive layer 103 on the surface of the doped conductive layer 103 away from the substrate 100.

In some embodiments, the pressure within the cool down stage chamber may be controlled between 550 and 650pa.

In some embodiments, the process parameters of the diffusion phase include: the process temperature is 800-850 ℃, such as 810 ℃, 820 ℃, 830 ℃ or 840 ℃ and the like, the process time is 100s-140s, the gas flow of the introduced nitrogen is 800-1200sccm, and the gas flow of the introduced oxygen is 400-800sccm. That is, in the step of compensating and expanding, the process temperature of the step of compensating and expanding is reduced to 840 ℃, then the process temperature of 840 ℃ is used for continuously compensating and expanding for 100s-140s, and nitrogen and oxygen are also introduced during the process, and the nitrogen is introduced to make the temperature in the whole chamber uniform, so that the temperature of the surfaces of the doped source layer 104 and the doped conductive layer 103 can be uniform, the uniformity of diffusion in the diffusion stage can be improved, and the oxygen is introduced to oxidize the doped conductive layer 103, so that the diffusion of doped ions into the doped conductive layer 103 can be facilitated.

It will be appreciated that the diffusion stage also needs to have a certain temperature to facilitate the diffusion of the dopant ions, so setting the process temperature of the diffusion stage to 800-850 ℃ can enable the diffusion stage to have a certain diffusion rate, thereby improving the diffusion rate of the diffusion stage and the doping effect of the diffusion stage.

In some embodiments, the number of the complementary diffusion steps is greater than 1, and the process temperature of the diffusion stage of the last complementary diffusion step may be greater than or equal to 800 ℃, so that the diffusion rate of the diffusion stage of the last complementary diffusion step may be ensured.

In some embodiments, the number of the complementary diffusion steps is greater than 1, and the process time period of the subsequent diffusion stage is greater than the process time period of the previous diffusion stage. Taking the number of the complementary expansion steps as 2 as an example, the 2 complementary expansion steps comprise: the first cooling stage, the first diffusion stage, the second cooling stage and the second diffusion stage, that is, the process temperature of the second diffusion stage is lower than that of the first diffusion stage, and the lower process temperature can lead to a slower reaction rate, so that the lower process temperature can be balanced by setting the process time of the second diffusion stage longer than that of the first diffusion stage, thereby leading the diffusion stage of the next time to have better complementary diffusion effect.

It should be noted that the number of the complementary expansion steps is 2, which is only an example, and the number of the complementary expansion steps may be other number, and the present disclosure is not limited to the number of the complementary expansion steps.

In some embodiments, the process duration of each diffusion stage is less than or equal to 180s, and the additional diffusion step can be avoided from increasing more process duration by setting the process duration of each diffusion stage to be less than or equal to 180 s.

It should be understood that, in practice, the diffusion stage and the cooling stage may be understood that, after the advancing step, the process temperature of the doping treatment needs to be reduced to the target temperature, and during the cooling process, the diffusion stage is performed, in other words, during the cooling process after the advancing step, cooling is stopped after cooling to a certain process temperature, so as to increase the doping concentration of the surface of the doped conductive layer 103, while in the related art, in order to ensure that the cooling process can be reduced to the target temperature, the process duration of the cooling stage is usually redundant, so that, by setting the process duration of each diffusion stage to be less than or equal to 180s, the doping concentration of the doped ions on the surface of the doped conductive layer 103 away from the substrate 100 may also be increased without increasing the process duration of the manufacturing method of the whole solar cell.

Referring to fig. 4, in some embodiments, the complementary expansion step further includes an on-source stage, where the on-source stage is used to form a doped sub-layer 105 on the first functional layer 106 after the cooling stage and before the diffusion stage, and the doped sub-layer 105 is doped with dopant ions. By providing the through-source stage, the doped sub-layer 105 may be formed on the first functional layer 106, and the doped ions in the doped source layer 104 may be supplemented by the doped sub-layer 105, so that diffusion of the doped ions toward the surface of the doped conductive layer 103 may be facilitated.

In some embodiments, the doping ions in the doping sub-layer 105 and the doping ions in the doping source layer 104 are the same, and the doping concentration of the doping ions in the doping sub-layer 105 may be the same as the doping concentration of the doping ions of the doping source layer 104 formed in the deposition step, that is, the method of forming the doping source layer 104 in the deposition step may be the same as the method of forming the doping sub-layer 105 in the through-source stage, thereby being beneficial to reducing the process difficulty of the solar cell.

It should be noted that, the formation of the doped sub-layer is an example for facilitating understanding of the change of the film layer, and the source-on stage may be to supplement the diffusion ions to the first functional layer, so that the thickness of the first functional layer in the direction perpendicular to the surface of the substrate may be increased during the supplementing process, and the doping concentration of the doped ions in the first functional layer may be increased.

Referring to fig. 5, in some embodiments, the dopant ions in the doped sub-layer 105 diffuse into the initial doped layer 113 after the complementary diffusion step, forming a doped conductive layer 103 with a higher doping concentration, and the remaining doped sub-layer 105 forms the second functional layer 107.

The first functional layer 106 and the second functional layer 107 may be phosphosilicate glass layers.

In some embodiments, the expanding step further includes a pumping stage for reducing the process gas pressure of the doping process to a predetermined pressure after the cooling stage and before the diffusing stage. The pumping stage can reduce the gas pressure in the diffusion stage, thereby facilitating the formation of the doped conductive layer 203.

In some embodiments, the preset air pressure is 150-250pa, for example, 160pa, 180pa, 200pa or 230pa, etc., the lower the air pressure in the doping stage, the higher the uniformity of the doping concentration on the surface of the formed doped conductive layer 203, and the lower the air pressure in the doping stage, the greater the process difficulty in the pumping stage, and the longer the process duration in the pumping stage, so by setting the preset air pressure to 150-250pa, the uniformity of the doping stage can be improved, the process difficulty in the pumping stage can be reduced, and the process duration in the pumping stage can be reduced.

In some embodiments, the pumping stage is 40-80 seconds in process duration. The process duration of the pumping stage is 40-80s, so that the process duration of the pumping stage is reduced while the process air pressure of the doping treatment can be reduced to the preset air pressure, and the process duration of the compensating and expanding step is prevented from being increased more.

In some embodiments, the step of compensating includes a pumping stage and a source stage, and the source stage is located after the pumping stage, and during the source stage, more gas containing the deposition material may be adsorbed on the surface of the first functional layer 106 by the pumping stage, so that the formation of the doped sub-layer 105 may be facilitated.

In some embodiments, the compensating and expanding step further includes a back pressure cooling stage, which is located after the compensating and expanding stage and is used for raising the reduced air pressure of the pumping stage again, so that the subsequent cooling step is facilitated, and the back pressure cooling stage can raise the air pressure in the chamber to 550-650 pa.

In some embodiments, the doping concentration of the doping ions within the doped conductive layer 103 is 1e20 to 1e21atoms/cm3. The field passivation effect of the solar cell can be optimized by setting the doping concentration of the doping ions in the doped conductive layer 103 to be 1e 20-1 e21atoms/cm3, so that good ohmic contact with a gate line formed subsequently is facilitated.

Referring to table one below, the following table one embodiment of the present disclosure provides a data parameter of a partial step provided by a method for manufacturing a solar cell, where time represents a process time, a chamber temperature represents an average temperature in a chamber, a chamber pressure represents an average pressure in the chamber, big nitrogen represents a flow of gas into the chamber, small nitrogen represents a flow of gas into the chamber, and the small nitrogen may carry a deposition material (e.g., phosphorus oxychloride), and oxygen represents a flow of gas into the chamber.

List one

Step (a)	time/S	Chamber temperature/°c	Chamber pressure/PA	Large nitrogen/sccm	Small nitrogen/sccm	Oxygen/sccm
							Boat feeding step	100	785	700	1000	0	0
Vacuumizing step	150	785	150	0	0	0
							Leak detection step	60	790	150	2000	1000	0
Pre-oxidation step	240	790	150	1000	1000	800
							Deposition step	950	801	150	1000	1400	600
Heating step	640	900	150	2500	0	600
							Advancing step	360	900	300	1000	1000	2000
Cooling stage	420	845	600	1000	1000	1000
							Pumping stage	60	840	200	1000	1000	1000
Source-through stage	120	840	200	1000	1400	600
							Diffusion stage	120	840	200	1000	1400	600
Back pressure cooling stage	120	780	600	1000	1000	1000
							A cooling step	460	750	600	1000	2000	0

Referring to the following table two, the experimental group in the following table two is the performance of the solar cell formed after the complementary expansion step, and the comparison group is the performance of the solar cell formed without the complementary expansion step, so that the photoelectric conversion efficiency, the filling factor and the short-circuit current of the solar cell are all increased.

Watch II

	Photoelectric conversion efficiency	Fill factor	Short-circuit current/mA
				Experimental group	25.47％	84.7399	13.6919
Comparison group	25.45％	84.6724	13.6861

By performing the one-time complementary diffusion step to form the doped conductive layer 103, the problem that the doping ions in the initial doped layer 113 move towards the substrate 100 in the advancing step, resulting in low doping concentration on the surface of the side of the initial doped layer 113 away from the substrate 100, can be improved, and the performance of the finally formed solar cell can be improved.

Referring to fig. 6 to 8 and 10, fig. 6 to 8 are temperature change diagrams of a second method for manufacturing a solar cell according to an embodiment of the disclosure, and fig. 10 is a temperature change diagram of a second method for manufacturing a solar cell according to an embodiment of the disclosure.

In some embodiments, the number of the complementary expansion steps is greater than 1. Taking the number of the complementary expansion steps as 2 as an example, the 2 complementary expansion steps comprise: a first cooling stage, a first source-passing stage, a first diffusion stage, a second cooling stage, a second source-passing stage and a second diffusion stage.

It should be noted that, the substrate 200, the tunneling layer 201, the first surface 210, the second surface 220, the initial doped layer 213, and the first functional layer 206 in fig. 6 to 8 are the same as the substrate 100, the tunneling layer 101, the first surface 110, the second surface 120, the initial doped layer 113, and the first functional layer 106 in the foregoing embodiments.

Referring to fig. 6, a first source-pass phase is performed to form a first doped sub-layer 215.

Referring to fig. 7, a first diffusion stage is performed in which at least part of the dopant ions in the first doped sub-layer 215 are diffused into the initial doped layer 213, forming a second doped layer 223 having a higher doping concentration than the initial doped layer 213, and the remaining first doped sub-layer 215 serves as the third functional layer 208.

The first diffusion stage is followed by a second cool-down stage, followed by a second pass-source stage to form a second doped sub-layer 225.

Referring to fig. 8, a second diffusion stage is performed in which at least part of the dopant ions in the second doped sub-layer 225 are diffused into the second doped layer 223 to form a doped conductive layer 203 having a higher doping concentration than the second doped layer 223, and the remaining second doped sub-layer serves as the fourth functional layer 209.

The third functional layer 208 and the fourth functional layer 209 may be phosphosilicate glass layers.

In some embodiments, the first pass source stage may form a first doped sub-layer 215 and the second pass source stage may form a second doped sub-layer 225, and the thickness of the first doped sub-layer 215 may be greater than the thickness of the second doped sub-layer 225.

It will be appreciated that the process temperature in the second diffusion stage is lower than the process temperature in the first diffusion stage, and the lower process temperature results in a slower reaction rate, that is, the concentration of the dopant ions diffused into the doped conductive layer in the second diffusion stage is smaller than that in the doped conductive layer in the first diffusion stage in a certain period of time, so that the thickness of the doped sub-layer formed in the last through source stage can be set to be smaller than that in the previous through source stage, which is beneficial to avoiding the process waste of the solar cell manufacturing method.

In some embodiments, the doping concentration of the doping ions in the doping sub-layer formed in the last through-source stage may be set to be smaller than the doping concentration of the doping ions in the doping sub-layer formed in the previous through-source stage, that is, the doping concentration of the doping ions in the second doping sub-layer 225 is smaller than the doping concentration of the doping ions in the first doping sub-layer 215, which is beneficial to reducing the process difficulty of the manufacturing method of the solar cell.

In the foregoing, the formation of the first doped sub-layer and the second doped sub-layer is an example for facilitating understanding of the change of the film layer, and in practice, the source-passing stage may also be to supplement diffusion ions to the first functional layer, where the thickness of the first functional layer in the direction perpendicular to the surface of the substrate may be increased in the supplementing process, and the doping concentration of the doping ions in the first functional layer may be increased, and the thickness of the doped sub-layer formed in the corresponding last source-passing stage is smaller than the thickness of the doped sub-layer formed in the previous source-passing stage, that is, the thickness of the first functional layer increased in the corresponding last source-passing stage is smaller than the thickness of the first functional layer increased in the previous source-passing stage, and the doping concentration of the doping ions in the doped sub-layer formed in the corresponding last source-passing stage is smaller than the doping concentration of the doping ions in the doped sub-layer formed in the previous source-passing stage.

In some embodiments, the process duration of each through-source stage may be 80-160s, and by setting the process duration of the through-source stage to be 80-160s, the process duration of the through-source stage may be avoided from being too long while forming a doped sub-layer in line with expectations.

It should be noted that, in this embodiment, the description is made for the multiple expansion steps, and other portions may refer to the description in the above-mentioned one expansion step, which is not repeated here.

It should be noted that, the methods in the foregoing embodiments may be arbitrarily combined, and the combined schemes also belong to the protection scope of the disclosure.

The disclosed embodiments provide a method for manufacturing a solar cell, which includes providing a substrate 100, forming a tunneling layer 101, forming a semiconductor layer 102, and performing doping treatment to form the solar cell, wherein the doping treatment includes: the deposition step, the heating step, the pushing step, the at least one complementary expansion step and the cooling step are sequentially performed, the deposition step is used for forming a doped source layer, the heating step is used for providing the process temperature of the pushing step, the pushing step is used for diffusing doped ions in the doped source layer into the semiconductor layer 102, the at least one complementary expansion step is used for conducting secondary diffusion into the doped conductive layer 103, so that the doped conductive layer 103 can be subjected to complementary diffusion, the field passivation effect of the solar cell is optimized, the problem of the reduction of the doping concentration on the surface of the doped conductive layer 103 caused by high-temperature pushing can be solved, the performance of the formed solar cell is improved, the process temperature of the whole solar cell manufacturing method can be reduced through the cooling step, and the solar cell can be taken out conveniently and the follow-up step is performed.

Another embodiment of the present disclosure further provides a solar cell, which may be formed by adopting the manufacturing method in some or all of the foregoing embodiments, and it is to be noted that the same or corresponding portions of the foregoing embodiments may be referred to the corresponding descriptions of the foregoing embodiments, and the description thereof will not be repeated.

In some embodiments, the solar cell may be a Topcon cell (Tunnel Oxide Passivated Contact solar cell tunnel oxide passivation contact solar cell), a PERC cell (Passivated Emitterand Rear Cell emitter back passivation cell), a stacked cell, or the like, which includes a tunnel layer (oxide or passivation layer) and a doped conductive layer.

It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples of implementing the disclosure, and that various changes in form and details may be made therein without departing from the spirit and scope of the embodiments of the disclosure. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the embodiments of the disclosure, and the scope of the embodiments of the disclosure should be assessed accordingly to that of the appended claims.

Claims

1. A method of manufacturing a solar cell, comprising:

providing a substrate comprising opposing first and second faces;

forming a tunneling layer, wherein the tunneling layer covers the second surface of the substrate;

forming a semiconductor layer, wherein the semiconductor layer covers the surface of the tunneling layer away from the second face;

performing doping treatment to diffuse doping ions into the semiconductor layer and convert the semiconductor layer into a doped conductive layer, wherein the doping treatment comprises:

the method comprises a deposition step, a heating step, a pushing step, at least one expansion supplementing step and a cooling step which are sequentially carried out;

the deposition step is used for forming a doped source layer on the semiconductor layer, wherein the doped source layer is doped with the doped ions;

the heating step is used for heating the process temperature of the doping treatment to the doping temperature;

the pushing step is used for keeping the process temperature of the doping treatment to be the doping temperature within a preset duration so as to diffuse the doping ions into the semiconductor layer;

the at least one complementary diffusion step is used for diffusing the doped ions into the semiconductor layer, and the complementary diffusion step comprises the following steps: the temperature reduction stage is used for reducing the process temperature of the doping treatment by a preset temperature, and the diffusion stage is used for diffusing the doping ions into the semiconductor layer at the process temperature after the temperature reduction stage is used for reducing the temperature;

The cooling step is used for reducing the process temperature of the doping treatment to the target temperature.

2. The method of claim 1, wherein the process parameters of the diffusion phase include: the process temperature is 800-850 ℃, the process time is 100-140 s, the gas flow of the introduced nitrogen is 800-1200sccm, and the gas flow of the introduced oxygen is 400-800sccm.

3. The method according to claim 1, wherein the number of the complementary diffusion steps is greater than 1, and the process time period of the subsequent diffusion stage is greater than the process time period of the previous diffusion stage.

4. A method of fabricating a solar cell according to claim 1 or 3, wherein the process duration per diffusion stage is 180s or less.

5. The method according to claim 1, wherein the complementary expansion step further comprises an on-source stage, the on-source stage being used to form a doped sub-layer on the doped source layer after the temperature-decreasing stage and before the diffusion stage, the doped sub-layer being doped with the dopant ions.

6. The method according to claim 5, wherein the number of the complementary expansion steps is greater than 1, and the thickness of the doped sub-layer formed in the last through-source stage is smaller than the thickness of the doped sub-layer formed in the previous through-source stage in the direction perpendicular to the first surface.

7. The method according to claim 5 or 6, wherein the number of the complementary expansion steps is greater than 1, and the doping concentration of the doping ions in the doping sub-layer formed in the last through-source stage is smaller than the doping concentration of the doping ions in the doping sub-layer formed in the previous through-source stage.

8. The method according to claim 1, wherein the step of expanding further comprises a pumping stage, the pumping stage being configured to reduce the process gas of the doping process to a predetermined pressure after the cooling stage and before the diffusion stage.

9. The method of claim 8, wherein the predetermined gas pressure is 150-250pa.

10. The method according to claim 1, wherein the doping concentration of the doping ions in the doped conductive layer is 1e20 to 1e21atoms/cm3.

11. The method according to claim 1, wherein the number of the expansion steps is greater than 1, and the temperature reduced in each cooling stage is the same.

12. A solar cell formed by the method of manufacturing a solar cell according to any one of claims 1 to 11.