Local doping method and device

Abstract

The present invention relates to the technical field of solar cells, and provides a local doping method and device. The local doping method includes: irradiating the surface to be doped of a silicon wafer with a light source, wherein the surface to be doped is provided with a region to be doped; mixing a doping source material with a carrier gas to form an aerosol; adding a charge to the aerosol, wherein the polarity of the charge is opposite to the polarity of the carriers on the surface to be doped; and spraying the aerosol with the charge added to the region to be doped. The local doping method provided by the present invention can complete the local doping by spraying the surface of the silicon wafer irradiated by the light source with the aerosol with the charge added, without the need to perform masking, laser grooving, acid washing and other processes on the silicon wafer, so that the silicon wafer undergoes fewer processes, thereby simplifying the process flow of local doping of the silicon wafer, thereby reducing the difficulty of local doping of the silicon wafer and improving the efficiency of local doping of the silicon wafer.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a local doping method and equipment. Background Art

[0002] During the processing of solar cells, it is necessary to heavily dope the contact area between the electrode and the silicon wafer to form a metallized area, so that the electrode contacts the area to form a good low-ohmic contact and reduce the loss caused by contact resistance. Light doping or zero doping is required in the non-electrode contact area to avoid the formation of a dead layer on the cell surface, thereby reducing the recombination loss of photogenerated electron-hole pairs.

[0003] In the prior art, local doping is usually performed through mask technology. Specifically, local doping using mask technology mainly includes the following steps: the first step is dry masking, placing the silicon wafer in an oxidation furnace to form a silicon dioxide mask on the surface of the silicon wafer. The second step is wet masking, which thickens the silicon dioxide mask on the surface of the silicon wafer. The third step is to use laser to etch the shallow gate groove. The fourth step is to pickle the shallow gate groove to remove the silicon oxide particles in the shallow gate groove. The fifth step is to place the silicon wafer in a doping furnace for doping, and the doping elements diffuse from the shallow gate groove into the silicon wafer.

[0004] The method of local doping using mask technology requires multiple steps such as masking, grooving, pickling and doping of silicon wafers, which makes the local doping process more complicated.

[0005] Therefore, the technical problem that technicians in this field urgently need to solve is how to simplify the process of local doping. Summary of the invention

[0006] The present invention provides a local doping method and device, which are used to solve the defect of the relatively complicated local doping process using mask technology in the prior art, and achieve the effect of simplifying the local doping process.

[0007] The present invention provides a local doping method for locally doping a silicon wafer, wherein the silicon wafer is provided with a carrier separation structure for causing the carriers excited by light on the silicon wafer to drift toward the surface of the silicon wafer, and the method comprises:

[0008] Using a light source to illuminate the surface to be doped of the silicon wafer, wherein the surface to be doped is provided with a region to be doped;

[0009] mixing a dopant source material with a carrier gas to form an aerosol;

[0010] Adding charges to the aerosol, wherein the polarity of the charges is opposite to the polarity of the carriers of the surface to be doped;

[0011] The aerosol to which the electric charge is added is sprayed toward the region to be doped.

[0012] According to a local doping method provided by the present invention, the region to be doped includes at least two parallel strip regions;

[0013] The step of spraying the aerosol with the electric charge added to the region to be doped comprises:

[0014] The aerosols carrying different types of the doping source materials are respectively sprayed toward two adjacent strip-shaped areas.

[0015] According to a local doping method provided by the present invention, the doping element in the doping source material includes at least one of boron, aluminum, gallium, indium, thallium and phosphorus;

[0016] And / or, the doping source material is a gaseous material, a liquid material or a paste material.

[0017] According to a local doping method provided by the present invention, the carrier gas includes at least one of nitrogen, argon, hydrogen and oxygen.

[0018] The present invention also provides a local doping device for locally doping a silicon wafer, wherein the silicon wafer is provided with a carrier separation structure for causing the carriers excited by light on the silicon wafer to drift toward the surface of the silicon wafer, and the device comprises:

[0019] A conveying mechanism, used for conveying the silicon wafer;

[0020] A light source, opposite to the conveying surface of the conveying mechanism, for irradiating the surface to be doped of the silicon wafer;

[0021] A mixing chamber structure, provided with an air inlet, a feed inlet and an air outlet, wherein the air inlet is used to introduce a carrier gas, the feed inlet is used to introduce a doping source material, the mixing chamber structure is used to mix the carrier gas and the doping source material to form an aerosol, and the air outlet faces the conveying surface and is used to spray the aerosol;

[0022] An electrostatic generating device is connected to the mixing cavity structure and is used to provide electric charges into the mixing cavity structure, wherein the polarity of the electric charges is opposite to the polarity of the carriers on the surface to be doped.

[0023] A local doping device provided according to the present invention further includes an adjusting mechanism, the mixing chamber structure is arranged on the adjusting mechanism, and the adjusting mechanism is used to adjust the distance between the gas outlet and the conveying surface.

[0024] According to a local doping device provided by the present invention, the number of the mixing chamber structures is at least two, and at least two of the mixing chamber structures are arranged along a conveying direction perpendicular to the conveying mechanism.

[0025] A local doping device provided according to the present invention further includes a heating device for heating the silicon wafer.

[0026] A local doping device provided according to the present invention further includes a shell, and the light source, the mixing cavity structure, the electrostatic generating device and at least a part of the conveying surface are all arranged in the shell.

[0027] A local doping device provided according to the present invention further includes a gas charging device, the shell is provided with a protective gas inlet and a protective gas outlet, and the gas charging device is connected to the protective gas inlet and is used to charge the protective gas into the shell.

[0028] The local doping method provided by the present invention irradiates the surface to be doped of the silicon wafer through a light source, and under the action of the carrier separation structure, the carriers drift to the surface to be doped, and then sprays an aerosol formed by mixing the doping source material and the carrier gas to the surface to be doped, and the aerosol is attached with charges of opposite polarity to the carriers on the surface to be doped. The charges and carriers are neutralized on the surface of the silicon wafer to generate local high temperature, and the doping elements in the aerosol diffuse into the interior of the silicon wafer under the action of the high temperature to form surface local doping.

[0029] With such an arrangement, the local doping method provided by the present invention can complete local doping by spraying an aerosol with an additional charge onto the surface of a silicon wafer irradiated by a light source, without the need to perform masking, laser grooving, acid washing and other processes on the silicon wafer, so that the silicon wafer undergoes fewer processes, thereby simplifying the process flow of local doping of silicon wafers, thereby reducing the difficulty of local doping of silicon wafers and improving the efficiency of local doping of silicon wafers.

[0030] At the same time, compared with the method of using mask technology for local doping in the prior art, it is necessary to place the entire silicon wafer in an oxidation furnace and a doping furnace, so that the entire silicon wafer is subjected to high temperature, which easily leads to a problem of reduced life of the silicon wafer. The local doping method provided by the present invention only forms high temperature at the location where the charge and carrier are neutralized, that is, the area to be doped, so that the silicon wafer does not need to be subjected to high temperature as a whole, thereby solving the problem that high temperature easily affects the life of the silicon wafer.

[0031] The local doping device provided by the present invention transports silicon wafers through a conveying mechanism, and a light source can illuminate the silicon wafer on the conveying mechanism. Under the action of the carrier separation structure of the silicon wafer, the carriers drift toward the surface to be doped. The carrier gas and the doping source material can be mixed to form an aerosol through a mixing chamber structure, and the aerosol is sprayed toward the silicon wafer on the conveying mechanism through an outlet. An electric charge is provided to the mixing chamber structure through an electrostatic generating device, so that the aerosol is attached with a charge of opposite polarity to the carrier on the surface to be doped. The charge and the carrier are neutralized on the surface of the silicon wafer to generate local high temperature, and the doping elements in the aerosol diffuse into the interior of the silicon wafer under the action of the high temperature to form surface local doping.

[0032] With such an arrangement, local doping is performed using the local doping equipment provided by the present invention without the need for steps such as masking, laser grooving and pickling. The local doping equipment can complete local doping by spraying a silicon wafer irradiated by a light source with an aerosol with an additional charge, and the process is simpler, thereby reducing the difficulty of local doping of silicon wafers and improving the efficiency of local doping of silicon wafers.

[0033] At the same time, compared with the method of using mask technology for local doping in the prior art, it is necessary to place the entire silicon wafer in an oxidation furnace and a doping furnace, so that the entire silicon wafer is subjected to high temperature, which easily leads to a problem of reduced life of the silicon wafer. The local doping equipment provided by the present invention is used for local doping, and high temperature is only formed in the part where the charge and carrier are neutralized, that is, the area to be doped, so that the silicon wafer does not need to be subjected to high temperature as a whole, thereby solving the problem that high temperature easily affects the life of the silicon wafer.

[0034] In addition, by setting up a conveying mechanism to convey silicon wafers, online continuous production of silicon wafers can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 is a schematic structural diagram of a local doping device provided in an embodiment of the present invention;

[0037] Figure 2 yes Figure 1 a side view of the view shown;

[0038] Figure 3 is a schematic structural diagram of another local doping device provided in an embodiment of the present invention;

[0039] Figure 4 is a schematic structural diagram of a mixing chamber structure provided in an embodiment of the present invention;

[0040] Figure 5 is a schematic structural diagram of a light source provided in an embodiment of the present invention;

[0041] Figure 6 yes Figure 5 Bottom view of the view shown.

[0042] Reference numerals:

[0043] 1. Silicon wafer; 2. Conveying mechanism; 3. Light source; 301. Carrying plate; 302. Lamp beads; 303. Cooling tube; 4. Mixing chamber structure; 401. Air inlet; 402. Feed inlet; 403. Air outlet; 5. Electrostatic generating device; 6. Adjusting mechanism; 7. Heating device; 8. Casing; 9. Inflating device. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] In the prior art, local doping is usually performed through mask technology. The method of performing local doping using mask technology requires multiple processes such as masking, grooving, pickling and doping on silicon wafers, which makes the process of local doping relatively complicated. In order to simplify the process of local doping, reduce the processing difficulty of local doping of silicon wafers, and improve the production capacity of silicon wafers, the present invention provides a local doping method and a local doping device.

[0046] Combine the following Figures 1 to 6 The local doping method provided in an embodiment of the present invention is described.

[0047] Specifically, the local doping method is used to perform local doping on the silicon wafer 1. The silicon wafer 1 is provided with a carrier separation structure, which is used to make the carriers of the silicon wafer 1 excited by light drift on the surface of the silicon wafer 1. Wherein, the carriers are electrons or holes. The carrier separation structure includes but is not limited to pn junctions, high-low junctions and passivation contact structures. It should be noted that pn junctions, high-low junctions and passivation contact structures are all existing structures in the field of solar cells, and are the basis for solar cells to produce photovoltaic effects. Their structure, principle and processing process are not the focus of this article, and will not be repeated here. In summary, processing a carrier separation structure on the silicon wafer 1 is the operating basis of the local doping method provided in the embodiment of the present invention. As for how to process the carrier separation structure, this article does not limit it.

[0048] Wherein, the local doping method comprises the steps of:

[0049] In the first step, a light source 3 is used to illuminate the surface to be doped of the silicon wafer 1, where a region to be doped is provided on the surface to be doped.

[0050] Specifically, the surface to be doped of the silicon wafer 1 is irradiated with the light source 3, and in response to the excitation of the light, the corresponding carriers drift toward the surface to be doped under the action of the carrier separation structure. That is, a photocurrent is generated by the irradiation of the light source 3. It should be noted that the area to be doped is an artificially defined area that needs to be doped.

[0051] Optionally, the light source 3 may be an LED lamp. For example, the light source 3 may be configured as a monochromatic LED lamp with an adjustable wavelength in the range of 300-1000 nm, and the light intensity of the LED lamp is ≥ 20 sun. Among them, 20 sun means 20 times the intensity of sunlight. Of course, the light source 3 is not limited to an LED lamp, for example, a halogen lamp may also be used.

[0052] The second step is to mix the doping source material with the carrier gas to form an aerosol.

[0053] Specifically, the doping source material and the carrier gas may be introduced into the mixing chamber structure 4 , and the two are mixed in the mixing chamber structure 4 to form an aerosol.

[0054] The third step is to add a charge to the aerosol. The polarity of the charge is opposite to the polarity of the carriers on the surface to be doped.

[0055] Specifically, the electrostatic generator 5 can be used to add charges with opposite polarity to the carriers of the surface to be doped to the aerosol. For example, the charges are introduced into the mixing cavity structure 4, where the charges are adsorbed on the particles of the aerosol, so that the aerosol carries the charges.

[0056] Step 4: Spray charged aerosol onto the area to be doped.

[0057] Specifically, according to the shape of the region to be doped, aerosol with electric charges is sprayed toward the region to be doped.

[0058] It should be noted that the above step numbers are only for the convenience of explaining the local doping method and should not be understood as limiting the local doping method. It can be understood by those skilled in the art that adjusting the sequence of the above steps does not affect the implementation of the local doping method. For example, before or at the same time as the first step, any one or combination of the second step, the third step and the fourth step can be implemented. Similarly, the third step can be implemented while the second step is implemented.

[0059] The local doping method provided in the embodiment of the present invention irradiates the surface to be doped of the silicon wafer 1 through the light source 3. Under the action of the carrier separation structure, the carriers drift to the surface to be doped, and then sprays an aerosol formed by mixing the doping source material and the carrier gas to the surface to be doped. The aerosol is attached with charges of opposite polarity to the carriers on the surface to be doped. The charges and carriers are neutralized on the surface of the silicon wafer 1 to generate local high temperature. Under the action of high temperature, the doping elements in the aerosol diffuse into the inside of the silicon wafer 1 to form surface local doping.

[0060] With such an arrangement, the local doping method provided in the embodiment of the present invention can complete the local doping by spraying the surface of the silicon wafer 1 irradiated by the light source 3 with an aerosol with an additional charge, without the need to perform masking, laser grooving, acid washing and other processes on the silicon wafer 1, so that the silicon wafer 1 undergoes fewer processes, thereby simplifying the process flow of local doping of the silicon wafer 1, thereby reducing the difficulty of local doping of the silicon wafer 1 and improving the efficiency of local doping of the silicon wafer 1.

[0061] At the same time, compared with the method of using mask technology for local doping in the prior art, it is necessary to place the silicon wafer 1 as a whole in an oxidation furnace and a doping furnace, so that the silicon wafer 1 as a whole is subjected to high temperature, which easily leads to the problem of reduced life of the silicon wafer 1. The local doping method provided in the embodiment of the present invention only forms high temperature at the location where the charge and carrier are neutralized, that is, the area to be doped, so that the silicon wafer 1 does not need to be subjected to high temperature as a whole, thereby solving the problem that high temperature easily affects the life of the silicon wafer 1.

[0062] In some embodiments provided by the present invention, the region to be doped includes at least two strip regions arranged in parallel.

[0063] Correspondingly, spraying aerosol with a charge onto the area to be doped includes:

[0064] Aerosols carrying different types of doping source materials are respectively sprayed toward two adjacent strip-shaped regions. It should be noted that different types of doping source materials refer to doping source materials containing different doping elements.

[0065] By doping different doping elements in two adjacent strip regions, interdigital doping can be formed on the surface of the silicon wafer 1. For example, for an IBC battery, the surface has p-regions and n-regions arranged in interdigital spacing. During the doping process, the surface of the battery to be doped is directed toward the light source 3, and aerosols containing different doping elements are sprayed toward the p-region and the n-region, respectively, so that the p-region and the n-region arranged in interdigital spacing can be prepared on the back of the battery.

[0066] In some embodiments provided by the present invention, a dielectric film is attached to the surface to be doped of the silicon wafer 1, and the conductivity of the dielectric film is lower than the conductivity of the surface to be doped of the silicon wafer 1. Since the current formed on the surface of the silicon wafer 1 by the charge carried by the aerosol will be conducted laterally along the surface of the silicon wafer 1, it may be conducted outside the area to be doped, resulting in the problem of doping in the non-doped area. By providing a dielectric film with relatively poor conductivity, the problem of lateral conduction of current along the surface of the silicon wafer 1 can be reduced, so that the controllability of the current formed by the charge is better, which is convenient for controlling the current in the area to be doped, so that the effect of local doping is better.

[0067] In some embodiments provided by the present invention, the doping element in the doping source material includes at least one of boron, aluminum, gallium, indium, thallium and phosphorus. For example, the above-mentioned various doping elements may exist in the form of simple substances or in oxides.

[0068] In some embodiments provided by the present invention, the doping source material is a gaseous material, a liquid material or a paste material.

[0069] In some embodiments provided by the present invention, the carrier gas includes at least one of nitrogen, argon, hydrogen and oxygen. Among them, nitrogen and argon can be used as a carrier gas and can also be used as a protective gas to cover the surface of the silicon wafer 1 to prevent the surface of the silicon wafer 1 from being oxidized. Using hydrogen as a carrier gas can make the silicon wafer 1 doped with hydrogen atoms. In some cases, hydrogen atoms can form a complex or precipitate with other impurities and point defects in the silicon wafer, remove the electrical activity of impurities, and play a passivation role, thereby greatly reducing the activity of point defects, dislocation defects and metal defects in the semiconductor substrate, thereby effectively improving the minority carrier lifetime and the conversion efficiency of solar cells. Using oxygen as a carrier gas is suitable for occasions where there is a need to oxidize the silicon wafer 1, and the surface of the silicon wafer 1 can be oxidized by oxygen.

[0070] A local doping device is also provided in an embodiment of the present invention.

[0071] Combination Figure 1-Figure 6 The local doping device provided in the embodiment of the present invention is introduced.

[0072] Specifically, the local doping device provided in the embodiment of the present invention is used for local doping of silicon wafer 1. The silicon wafer 1 is provided with a carrier separation structure, which is used to make the carriers excited by light on the silicon wafer 1 drift to the surface of the silicon wafer 1. Wherein, the carrier is an electron or a hole. The carrier separation structure includes but is not limited to a pn junction, a high-low junction and a passivation contact structure. It should be noted that the pn junction, the high-low junction and the passivation contact structure are all existing structures in the field of solar cells, and are the basis for solar cells to produce the photovoltaic effect. The structure, principle and processing process thereof are not the focus of this article and will not be repeated here. In summary, processing the carrier separation structure on the silicon wafer 1 is the basis for the operation of the local doping device provided in the embodiment of the present invention. As for how to process the carrier separation structure, this article does not limit it.

[0073] The local doping device includes a conveying mechanism 2, a light source 3, a mixing cavity structure 4 and an electrostatic generating device 5.

[0074] The conveying mechanism 2 is used to convey the silicon wafer 1. For example, the conveying mechanism 2 can be a metal crawler conveying mechanism or a ceramic roller conveying mechanism.

[0075] Optionally, the conveying speed of the conveying mechanism 2 may be 0.5 m-3 m / s.

[0076] The light source 3 is opposite to the conveying surface of the conveying mechanism 2, and is used to illuminate the surface to be doped of the silicon wafer 1 on the conveying mechanism 2. Optionally, the light source 3 can be an LED lamp. For example, the light source 3 can be configured as a monochromatic LED lamp with an adjustable wavelength in the range of 300-1000nm, and the light intensity of the LED lamp is ≥20sun. Among them, 20sun means 20 times the intensity of sunlight. For example, the LED lamp includes a carrier plate 301, a lamp bead 302 and a cooling tube 303. Among them, the lamp bead 302 and the cooling tube 303 are arranged on the carrier plate 301. The cooling tube 303 can be used to pass a coolant to cool the lamp bead 302 to avoid the lamp bead 302 from being too high in temperature. The lamp bead 302 and the cooling tube 303 are respectively arranged on two surfaces of the carrier plate 301. At least one of the cooling tube 303 and the carrier plate 301 is set to aluminum or copper. Of course, the light source 3 is not limited to an LED lamp, for example, a halogen lamp can also be used.

[0077] The mixing chamber structure 4 is provided with an air inlet 401, a feed port 402 and an air outlet 403. The air inlet 401 is used to introduce a carrier gas, and the feed port 402 is used to introduce a doping source substance. The mixing chamber structure 4 is configured as a cavity structure, and the mixing chamber structure 4 is used to mix the carrier gas and the doping source substance to form an aerosol. The air outlet 403 faces the conveying surface of the conveying mechanism 2, and is used to spray the aerosol toward the silicon wafer 1. Among them, the number of the air inlets 401, the number of the gas outlets 403 and the number of the gas outlets 403 are not limited to one. The doping source substance can be directly introduced into the feed port 402, or it can be introduced into the feed port 402 by gas conveying.

[0078] The electrostatic generating device 5 is connected to the mixing cavity structure 4, and is used to provide charges into the mixing cavity structure 4, and the polarity of the charges is opposite to the polarity of the carriers on the surface to be doped. For example, the electrostatic generating device 5 is an electrostatic generator, and the transmitting end of the electrostatic generator is arranged inside the mixing cavity structure 4, and is used to provide charges into the mixing cavity structure 4. It should be noted that the electrostatic generator belongs to the product in the prior art, and its structure and principle are not the focus of this article, and will not be repeated here.

[0079] The local doping device provided in the embodiment of the present invention transports the silicon wafer 1 through the conveying mechanism 2, and the light source 3 can irradiate the silicon wafer 1 on the conveying mechanism 2. Under the action of the carrier separation structure of the silicon wafer 1, the carriers drift to the surface to be doped. The carrier gas and the doping source material can be mixed to form an aerosol through the mixing chamber structure 4, and the aerosol is sprayed to the silicon wafer 1 on the conveying mechanism 2 through the gas outlet 403. The electrostatic generator 5 provides an electric charge to the mixing chamber structure 4, so that the aerosol is attached with an electric charge with the opposite polarity to the carrier of the surface to be doped. The charge and the carrier are neutralized on the surface of the silicon wafer 1 to generate a local high temperature, and the doping elements in the aerosol diffuse into the silicon wafer 1 under the action of the high temperature to form a surface local doping.

[0080] With such an arrangement, local doping is performed using the local doping device provided in the embodiment of the present invention without the need for steps such as masking, laser grooving and pickling. The local doping device can complete local doping by spraying aerosol with an additional charge on the silicon wafer 1 irradiated by the light source 3. The process is simpler, thereby reducing the difficulty of local doping of the silicon wafer 1 and improving the efficiency of local doping of the silicon wafer 1.

[0081] At the same time, compared with the method of using mask technology for local doping in the prior art, it is necessary to place the silicon wafer 1 as a whole in an oxidation furnace and a doping furnace, so that the silicon wafer 1 as a whole is subjected to high temperature, which easily leads to the problem of reduced life of the silicon wafer 1. Local doping is performed using the local doping equipment provided in the embodiment of the present invention, and high temperature is only formed in the part where the charge and carrier are neutralized, that is, the area to be doped, so that the silicon wafer 1 does not need to be subjected to high temperature as a whole, thereby solving the problem that high temperature easily affects the life of the silicon wafer 1.

[0082] In addition, by providing a conveying mechanism 2 to convey the silicon wafers 1 , online continuous production of the silicon wafers 1 can be achieved.

[0083] In some embodiments provided by the present invention, the mixing chamber structure 4 further includes a nozzle, which is disposed at the gas outlet 403. The nozzle can be provided to form a convergence effect on the aerosol, so that the diameter of the aerosol airflow ejected from the nozzle can be made thinner. As the conveying mechanism 2 drives the silicon wafer 1, the nozzle ejects the airflow, and a linear doping area can be formed on the surface of the silicon wafer 1.

[0084] In some embodiments provided by the present invention, the local doping device further includes an adjusting mechanism 6 , the mixing chamber structure 4 is disposed on the adjusting mechanism 6 , and the adjusting mechanism 6 is used to adjust the distance between the gas outlet 403 and the conveying surface of the conveying mechanism 2 .

[0085] Since the airflow ejected from the air outlet 403 is generally conical, that is, the farther away from the air outlet 403, the larger the diameter of the airflow, the width of the linear doping region can be adjusted by adjusting the distance between the air outlet 403 and the conveying surface. For example, by adjusting the distance between the air outlet 403 and the conveying surface through the adjustment mechanism 6, the width of the linear doping region can be adjusted to a range of 5 μm-120 μm.

[0086] Optionally, the adjustment mechanism 6 can be a screw nut lifting mechanism. For example, the screw nut driving mechanism includes a bracket, a lifting seat, a screw nut driving mechanism and a motor. Among them, the bracket is fixedly arranged, for example, it can be connected and fixed to the ground or connected and fixed to the frame of the conveying mechanism 2. The lifting seat is slidably arranged on the bracket, and the screw nut driving mechanism is arranged on the bracket and connected to the lifting seat, which is used to drive the lifting seat to move. The motor is arranged on the bracket and connected to the screw nut driving mechanism, which is used to provide power for the screw nut driving mechanism.

[0087] refer to Figure 1 As shown, the number of the mixing chamber structures 4 is at least two, and at least two mixing chamber structures 4 are arranged along a conveying direction perpendicular to the conveying mechanism 2. With such an arrangement, on the one hand, a local doping device can be used to perform local doping on multiple silicon wafers 1 at the same time. On the other hand, by alternately arranging aerosols carrying different types of doping source substances in at least two mixing chamber structures 4, finger doping can be formed on the surface of the silicon wafer 1. For example, for an IBC battery, the surface has p-regions and n-regions arranged in finger-like intervals. During the doping process, the surface of the battery to be doped is directed toward the light source 3, and aerosols containing different doping elements are sprayed into the p-region and the n-region respectively through the corresponding mixing chamber structure 4, so that the p-region and the n-region arranged in finger-like intervals can be prepared on the back of the battery. It should be noted that different types of doping source substances refer to doping source substances containing different doping elements.

[0088] Optionally, refer to Figure 1 As shown, multiple silicon wafers 1 can be arranged along a conveying direction perpendicular to the conveying mechanism 2. There are multiple groups of mixing chamber structures 4, which are respectively opposite to the corresponding silicon wafers 1, and each group is provided with multiple mixing chamber structures 4. In this way, multiple silicon wafers 1 can be locally doped at the same time, and interdigital doping can be prepared on each silicon wafer 1.

[0089] In some embodiments provided by the present invention, the local doping device further includes a heating device 7 for heating the silicon wafer 1. By providing the heating device 7, a basic temperature can be provided for the silicon wafer 1 when necessary, so that the doping elements can diffuse into the silicon wafer 1, thereby enabling a better local doping effect to be formed on the surface of the silicon wafer 1. For example, the heating device 7 can be an infrared heating device 7.

[0090] Optionally, the heating device 7 may be arranged above, below or on both sides of the silicon wafer 1 in the running direction.

[0091] Optionally, the temperature range of the heating device 7 is 180°C-850°C.

[0092] In some embodiments provided by the present invention, the local doping device further comprises a housing 8, and the light source 3, the mixing cavity structure 4, the electrostatic generating device 5 and at least part of the conveying surface are all arranged in the housing 8. Such arrangement can prevent external substances from interfering with the doping process, so as to ensure the local doping effect.

[0093] In some embodiments provided by the present invention, the local doping device further includes a gas charging device 9, the housing 8 is provided with a protective gas inlet and a protective gas outlet, and the gas charging device 9 is connected to the protective gas inlet and is used to charge the protective gas into the housing 8. By passing the protective gas into the housing 8, other gases or particulate impurities floating in the air are prevented from entering the housing 8 to interfere with the local doping process, so as to further ensure the local doping effect. For example, the gas charging device 9 includes but is not limited to a pressure vessel storing protective gas.

[0094] Optionally, the protective gas includes but is not limited to argon and nitrogen.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A local doping method, characterized in that: For locally doping a silicon wafer (1), the silicon wafer (1) being provided with a carrier separation structure, for causing carriers excited by light on the silicon wafer (1) to drift toward a surface of the silicon wafer (1), the method comprising: Using a light source (3) to irradiate the surface to be doped of the silicon wafer (1), wherein the surface to be doped is provided with a region to be doped; mixing a dopant source material with a carrier gas to form an aerosol; Adding charges to the aerosol, wherein the polarity of the charges is opposite to the polarity of the carriers of the surface to be doped; The aerosol with the charge added is sprayed toward the area to be doped; the charge and the carrier are neutralized on the surface of the silicon wafer to generate local high temperature, and the doping elements in the aerosol diffuse into the inside of the silicon wafer under the action of the high temperature to form surface local doping; The surface to be doped of the silicon wafer (1) is provided with a dielectric film, and the conductivity of the dielectric film is lower than the conductivity of the surface to be doped of the silicon wafer (1); The light source is adjustable within the wavelength range of 300-1000nm and is used to irradiate the surface to be doped of the silicon wafer to generate photocurrent.

2. The local doping method according to claim 1, characterized in that: The region to be doped includes at least two strip regions arranged in parallel; The step of spraying the aerosol with the electric charge added to the region to be doped comprises: The aerosols carrying different types of the doping source materials are respectively sprayed toward two adjacent strip-shaped areas.

3. The local doping method according to claim 1, characterized in that: The doping element in the doping source material includes at least one of boron, aluminum, gallium, indium, thallium and phosphorus; And / or, the doping source material is a gaseous material, a liquid material or a paste material.

4. The local doping method according to claim 1, characterized in that: The carrier gas includes at least one of nitrogen, argon, hydrogen and oxygen.

5. A local doping device, characterized in that: Used for locally doping a silicon wafer (1), the silicon wafer (1) being provided with a carrier separation structure, used for causing carriers excited by light on the silicon wafer (1) to drift toward the surface of the silicon wafer (1), the device comprising: A conveying mechanism (2) for conveying the silicon wafer (1); A light source (3), opposite to the conveying surface of the conveying mechanism (2), and used for irradiating the surface to be doped of the silicon wafer (1); The mixing chamber structure (4) is provided with an air inlet (401), a material inlet (402) and an air outlet (403), wherein the air inlet (401) is used to introduce a carrier gas, the material inlet (402) is used to introduce a doping source material, the mixing chamber structure (4) is used to mix the carrier gas and the doping source material to form an aerosol, and the air outlet (403) faces the conveying surface and is used to spray the aerosol; An electrostatic generating device (5) connected to the mixing cavity structure (4) and used for providing electric charges into the mixing cavity structure (4), wherein the polarity of the electric charges is opposite to the polarity of the carriers of the surface to be doped; The surface to be doped of the silicon wafer (1) is covered with a dielectric film, and the conductivity of the dielectric film is lower than the conductivity of the surface to be doped of the silicon wafer (1); the light source is adjustable within a wavelength range of 300-1000nm and is used to irradiate the surface to be doped of the silicon wafer to generate photocurrent.

6. The local doping device according to claim 5, characterized in that: It also comprises an adjusting mechanism (6), the mixing chamber structure (4) is arranged on the adjusting mechanism (6), and the adjusting mechanism (6) is used to adjust the distance between the air outlet (403) and the conveying surface.

7. The local doping device according to claim 5, characterized in that: The number of the mixing chamber structures (4) is at least two, and at least two of the mixing chamber structures (4) are arranged along a conveying direction perpendicular to the conveying mechanism (2).

8. The local doping device according to claim 5, characterized in that: It also comprises a heating device (7) for heating the silicon wafer (1).

9. The local doping device according to claim 5, characterized in that: It also comprises a shell (8), wherein the light source (3), the mixing chamber structure (4), the electrostatic generating device (5) and at least a part of the conveying surface are all arranged in the shell (8).

10. The local doping device according to claim 9, characterized in that: It also comprises a gas charging device (9), the outer shell (8) is provided with a protective gas inlet and a protective gas outlet, and the gas charging device (9) is connected to the protective gas inlet and is used for charging the protective gas into the outer shell (8).

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