PECVD system and coating method for depositing multiple film layers and featuring gas uniformity.

Abstract

This invention belongs to the field of solar cell manufacturing, specifically relating to a PECVD system and coating method for depositing multiple film layers and having a gas uniformity function. Corresponding gas distribution boxes are set up for different reaction chambers, and the gas distribution boxes disperse and uniformly distribute the airflow. Furthermore, the gas distribution boxes control the flow rate in the central and peripheral areas separately to ensure that the gas concentration in different areas is as consistent as possible. Simultaneously, the structural distribution of the inclined laminar flow plate in conjunction with the central gas uniformity plate further improves the airflow uniformity in each area of ​​the large chamber, thereby improving the uniformity of the coated film layers and ultimately enhancing the quality and stability of the solar cells.

Description

Technical Field

[0001] This invention belongs to the field of solar cell manufacturing technology, specifically relating to a PECVD system and coating method for depositing multiple film layers and having a gas uniformity function. Background Technology

[0002] To meet the demand for large-scale production and large-size coating of heterojunction solar cells, the PECVD chambers on the market are gradually becoming larger. The increased coating area inside the chamber will affect the coating uniformity of silicon wafers and the uniformity of remote plasma cleaning.

[0003] Process gases are introduced into the gas distribution box within the chamber through multiple inlets. Under the influence of pressure difference, the process gases are dispersed and uniformly distributed within the distribution box. High-capacity PECVD equipment has a large coating area and short cycle times, making it easy for process gases to escape directly through the uniform distribution holes near the inlets. This results in locally thicker coatings and thinner coatings on silicon wafers further away from the inlets, leading to significant thickness variations in the coating thickness of individual silicon wafers. Similarly, when using RPS to clean the chamber or carrier, uneven and incomplete cleaning occurs.

[0004] It should be noted that this part of the present invention only provides background technology related to the present invention, and does not necessarily constitute prior art or known technology. Summary of the Invention

[0005] The purpose of this invention is to provide a PECVD system and coating method for depositing multiple film layers and having a uniform gas distribution function, so as to overcome the problem that uneven airflow in the large cavity of existing PECVD equipment has a significant impact on coating quality.

[0006] To achieve the above objectives, in a first aspect, embodiments of the present invention provide a PECVD system for depositing multiple film layers and having a gas uniformity function, used for fabricating heterojunction solar cells. The PECVD system includes an infeed preheating chamber, a one-stop coating module, and a cooling and exiting chamber connected sequentially via gate valves. The one-stop coating module includes an isolation chamber and several process chambers for depositing different film layers. Each process chamber includes:

[0007] A cavity structure, the cavity structure including a cavity cover, a cavity bottom and a reaction chamber located between the cavity cover and the cavity bottom, wherein a carrier plate for supporting the workpiece is disposed in the reaction chamber;

[0008] An air distribution box is disposed between the cavity cover and the carrier plate. The air distribution box is divided into a central air distribution area and a peripheral air distribution area. The airflow in the central air distribution area and the peripheral air distribution area is controlled by corresponding control valves to adjust the airflow rate in the corresponding area.

[0009] The air distribution box includes an upper air distribution plate, a lower air distribution plate, and an air inlet pipe assembly located on the upper surface of the upper air distribution plate. An air equalization plate and multiple laminar flow plates are arranged between the upper air distribution plate and the lower air distribution plate. The air equalization plate is located in the central air equalization area, and the multiple laminar flow plates are respectively located in the peripheral air equalization areas and surround the air equalization plate. The laminar flow plates are all inclined at a certain angle, and the edge near the air equalization plate is higher than the edge away from the air equalization plate.

[0010] The control unit is electrically connected to each of the control valves and is used to adjust the parameters of the corresponding control valves according to the uniformity of the previous coating in the current process chamber.

[0011] Optionally, the PECVD system for depositing multiple film layers and having a gas uniformity function further includes:

[0012] A heating element is disposed at the bottom of the carrier plate and is used to heat the carrier plate and the reaction chamber.

[0013] A temperature detection component is disposed around the heating component and is used to detect the temperature of the corresponding area;

[0014] The control unit is connected to the temperature detection component and the heating component respectively, and is used to set the temperature of the heating component according to the current coating temperature requirement in the process chamber, and adjust the parameters of the corresponding control valve according to the detected temperature compensation.

[0015] Optionally, a first air inlet is provided at the center of the upper air distribution plate, and a plurality of second air inlets are provided around the upper air distribution plate; the air equalization plate is located below the first air inlet, and the laminar flow plate is located below the second air inlets;

[0016] One end of the intake pipe assembly is used to connect to the intake pipe. The intake pipe assembly includes: multiple branch pipes and corresponding control valves disposed on the branch pipes. The first intake port and the second intake port are respectively connected to the corresponding branch pipes, and the first intake port and the second intake port are adjusted by the control valves on the corresponding branch pipes.

[0017] Optionally, the ratio of the distance from the second air inlet along the first direction to the first air inlet to the distance from the first air inlet to the side wall of the chamber is in the range of 2 / 5 to 3 / 5; the ratio of the distance from the second air inlet along the second direction to the first air inlet to the distance from the first air inlet to the side wall of the chamber is in the range of 2 / 5 to 3 / 5; wherein, the first direction is the direction of one of the central symmetry lines of the air distribution box, and the second direction is the direction of the other central symmetry line of the air distribution box.

[0018] Optionally, the gas equalization plate is a disc structure, and the gas equalization plate is provided with a plurality of gas equalization holes arranged in a circumferential array, and the plurality of gas equalization holes are arranged to form a plurality of rings with gradually changing diameters.

[0019] Optionally, the number of laminar flow plates is four, and the four laminar flow plates are evenly distributed around the air distribution plate. The orthographic projections of the four laminar flow plates on the lower air distribution plate enclose and form an intermittent circular structure.

[0020] Optionally, the air distribution plate is provided with baffles on both sides along the first direction, and the baffles extend to the four laminar flow plates at the corresponding positions at both ends along the first direction, with a preset gap between the baffles and the laminar flow plates.

[0021] Optionally, the end of the baffle plate is biased outward in the second direction along the first direction, so that an airflow diffuser is formed between the ends of the baffle plate at the same end, and the airflow diffuser faces the discontinuous region along the second direction between two adjacent laminar flow plates; wherein, the second direction is the direction of another central symmetry line of the air distribution box.

[0022] Optionally, the diffusion angle of the airflow diffuser is 60~120°.

[0023] Optionally, the cavity cover is further provided with a third air inlet, which is a composite air inlet, and the upper end of the third air inlet is connected to the air inlet pipe and the cleaning pipe respectively.

[0024] The cleaning pipe is used to introduce a remote plasma source gas flow into the reaction chamber when the chamber needs to be cleaned. The gas distribution box is also equipped with a cleaning flow equalization baffle, which is located below the third air inlet.

[0025] Optionally, the ratio of the distance from the third air inlet to the first air inlet along the second direction to the distance from the second air inlet to the first air inlet along the second direction is between 1 / 3 and 4 / 5.

[0026] Optionally, the cleaning flow equalization baffle is located on the side of the baffle away from the air equalization plate, and is directly opposite the discontinuous region along the first direction between two adjacent laminar flow plates.

[0027] Optionally, the lower air distribution plate has multiple air outlets, which are arranged in a linear array.

[0028] Optionally, the intake piping assembly includes a diaphragm valve; the diaphragm valve is disposed on the connection pipe between the control valve and the intake piping, and is used to control the opening and closing of the intake piping.

[0029] Optionally, the PECVD system for depositing multiple film layers and having a gas equalization function further includes: an exhaust channel; an exhaust control valve is provided on the exhaust channel, and a flow equalization screen covering the exhaust channel is provided on the bottom of the chamber, the flow equalization screen having multiple mesh holes.

[0030] Optionally, an air-blocking assembly is provided between the carrier plate and the cavity bottom. The air-blocking assembly has a semi-closed annular structure and is used to delay the airflow around the air-blocking assembly from being discharged from the exhaust channel.

[0031] Optionally, the air-blocking assembly includes: a movable baffle, a flexible baffle, and a fixed baffle; the movable baffle is fixed around the bottom of the heating component, the fixed baffle is disposed on the cavity bottom and surrounds the lower edge of the movable baffle, and a preset gap is left between the fixed baffle and the movable baffle; the flexible baffle is disposed between the heating component and the cavity bottom, and is located inside the movable baffle, and the flexible baffle is provided with gas inlets at the four corners of the cavity structure respectively.

[0032] Optionally, the PECVD system for depositing multiple film layers and having a gas equalization function further includes: a lifting mechanism; the lifting mechanism includes a lifting rod and a driving mechanism; the driving mechanism is located below the bottom of the cavity, one end of the lifting rod is connected to the driving mechanism, and the other end passes through the bottom of the cavity and is connected to the bottom of the heating component.

[0033] In a second aspect, the present invention also provides a coating method employing the PECVD system described in the first aspect, the coating method comprising:

[0034] S1. Feeding and preheating: Silicon wafers are placed on the carrier plate and stacked into multiple layers; a batch is conveyed to the stacking lifting mechanism of the wafer feeding preheating cavity for preheating;

[0035] S2. Coating: The preheated multilayer carrier plates are transported in batches to the first process chamber, and the first film layer is deposited on the carrier plates through a one-stop deposition method. Then, the multilayer carrier plates are transported in batches to the isolation chamber for gas washing and vacuuming, and then transported in batches to the second process chamber, where the second film layer is deposited on the carrier plates through a one-stop deposition method. This process is repeated for several layers until the coating process is completed. When coating in any process chamber, the parameters of the corresponding control valve are adjusted according to the uniformity of the previous coating in the current process chamber.

[0036] S3. Cooling and Unloading: The coated carrier boards are transported in batches to the stacking lifting mechanism of the cooling and unloading chamber for cooling. After cooling, they are transported to the unloading machine to unload the silicon wafers.

[0037] The embodiments of the present invention have at least the following technical effects:

[0038] The PECVD system and coating method for depositing multiple film layers with gas uniformity provided in this invention embodiment sets up corresponding gas distribution boxes for different reaction chambers, and disperses and uniformizes the airflow by setting up gas distribution boxes. Specifically, based on the uniformity of the previous coating, the airflow in different areas is controlled separately, especially for the surrounding areas of the chamber, to appropriately compensate for the airflow, so as to reduce the impact of uneven airflow distribution in the large PECVD chamber on the deposited film layer. At the same time, the special design of the inclined laminar flow plate surrounding the gas uniformity plate makes it easier for the airflow to be dispersed to the surrounding areas, thus ensuring the uniformity of airflow in each area of ​​the large chamber as much as possible. Furthermore, by setting up cleaning and flow uniformity baffles and baffles between the gas uniformity plate and the laminar flow plate, and the inclined laminar flow plate and the gas uniformity plate working together to form a special flow uniformity channel, and by cooperating with diaphragm valves and control valves to control the airflow, the uniformity of airflow distribution in the reaction chamber is further improved, which is more conducive to improving the uniformity of the coated film layer, thereby improving the quality and stability of solar cells. Attached Figure Description

[0039] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the overall structure of a PECVD system for depositing multiple film layers and having a gas uniformity function, provided in an embodiment of the present invention.

[0041] Figure 2 This is a schematic diagram of the internal structure of a cavity structure provided in an embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of the cavity cover and air distribution box of the cavity structure provided in an embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram of the structure of the air distribution box provided in an embodiment of the present invention;

[0044] Figure 5 This is a schematic diagram of the internal structure of another cavity structure provided in an embodiment of the present invention;

[0045] Figure 6 This is a schematic diagram of the internal bottom view of another cavity structure provided in an embodiment of the present invention;

[0046] Figure 7This is a schematic diagram of the cavity bottom of another cavity structure provided in an embodiment of the present invention;

[0047] Figure 8 This is a flowchart of a coating method for a PECVD system with gas uniformity function for coating multiple film layers, provided as an embodiment of the present invention.

[0048] Figure label:

[0049] 100 - Preheating chamber for wafer feeding; 200 - First process chamber; 300 - Second process chamber; 400 - Third process chamber; 500 - Isolation chamber; 600 - Cooling and wafer ejection chamber;

[0050] 1-Cavity structure; 101-Cavity cover; 102-Cavity bottom; 103-Reaction chamber; 2-Gas distribution box; 201-Upper gas distribution plate; 3-Diaphragm valve; 4-Control valve; 501-First air inlet; 502-Second air inlet; 503-Third air inlet; 6-Gas equalization plate; 7-Laminar flow plate; 8-Cleaning and equalization baffle; 9-Baffle plate; 10-Lower gas distribution plate; 11-Carrier plate; 12-Moving baffle; 13-Flexible baffle; 14-Fixed baffle; 15-Frame; 16-Heating component; 17-Lifting rod; 18-Drive mechanism; 19-Exhaust channel; 20-Inlet pipe. Detailed Implementation

[0051] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0053] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The term “and / or” as used herein includes all or any units and all combinations of one or more associated listed items.

[0054] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0055] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0056] like Figure 1 As shown, this embodiment of the invention provides a PECVD system for depositing multiple film layers and having a gas uniformity function, used to prepare heterojunction solar cells. The PECVD system includes an infeed preheating chamber 100, a one-stop coating module, and a cooling and exiting chamber 600 connected sequentially by valves. The one-stop coating module includes an isolation chamber 500 and several process chambers for depositing different film layers. Optionally, the number of process chambers for depositing the same film layer can be multiple. When there are multiple process chambers, considering the requirement of gas uniformity, adjacent process chambers are separated by openable or closable valves. The valves are opened when the carrier plate 11 is needed for transfer and closed to seal during the reaction. The process chambers for depositing the same film layer refer to process chambers that deposit all i-layers (i.e.,...). Figure 1 The first process cavity 200), or the process cavity that is plated with a p-layer (i.e. Figure 1 The second process chamber 300 in the middle), or the process chambers where other films are deposited (i.e. Figure 1 The third process chamber 400 is used for subsequent film layers after the p-layer deposition (it is an add-on chamber). The structure of the process chamber is described in detail below. Figures 2 to 5As shown, the process chamber includes: chamber structure 1, air distribution box 2, heating component 16, temperature detection component, and control unit (not shown in the figure).

[0057] Specifically, the cavity structure 1 includes a cavity cover 101, a cavity bottom 102, and sidewalls. The space between the cavity cover 101 and the cavity bottom 102 forms a reaction chamber 103. A carrier plate 11 for carrying the workpiece is disposed inside the reaction chamber 103. The carrier plate 11 can be supported by a support member below it, and the carrier plate 11 can be moved or raised and lowered according to specific process requirements. A heating element 16 is disposed at the bottom of the carrier plate 11 for heating the carrier plate 11 and the reaction chamber 103. The cavity cover 101 is connected to the gas inlet pipe 20, allowing the reaction gas or purge gas to enter the chamber for deposition reaction or film cleaning.

[0058] The gas distribution box 2 is disposed between the chamber cover 101 and the carrier plate 11, that is, the gas distribution box 2 is located above the carrier plate 11. The gas distribution box 2 is used to disperse and evenly distribute the gas entering from the air inlet pipe 20 to ensure the uniformity of airflow distribution in the reaction chamber 103, thereby improving the uniformity of the coating thickness.

[0059] To better control the airflow in different areas within the reaction chamber 103, the gas distribution box 2 is divided into a central uniform gas distribution area and a peripheral uniform gas distribution area. For example, with the center of the top of the chamber cover 101 as the origin, the area within a preset radius is called the central uniform gas distribution area, and the peripheral area at a preset distance from the central uniform gas distribution area is called the peripheral uniform gas distribution area. The peripheral uniform gas distribution area can be evenly distributed around the central uniform gas distribution area. The airflow in the central uniform gas distribution area and the peripheral uniform gas distribution area are controlled by corresponding control valves 4 to adjust the airflow flow rate in their respective areas. For example, when the airflow flow rate in the central uniform gas distribution area is large, it is necessary to distribute the airflow evenly to the peripheral uniform gas distribution area. This can be achieved by increasing the opening of the control valve 4 corresponding to the airflow in the peripheral uniform gas distribution area or decreasing the opening of the control valve 4 corresponding to the airflow in the central uniform gas distribution area. Of course, the specific control method needs to be adjusted based on the airflow requirements of the coating reaction, and no specific limitation is made here.

[0060] It should be noted that, in this embodiment of the invention, by detecting the coating thickness of the reaction chamber after the previous reaction, the coating uniformity indirectly characterizes the airflow distribution uniformity within the chamber to a certain extent, thereby providing a basis for adjusting the control valve 4 for airflow in different areas.

[0061] The PECVD system provided in this invention provides corresponding gas distribution boxes for different reaction chambers. By setting up the gas distribution boxes, the airflow is dispersed and uniformly distributed. Specifically, based on the uniformity of the previous coating, the airflow flow rate of the corresponding area is controlled separately for different areas. In particular, appropriate airflow compensation is performed for the surrounding area of ​​the chamber to reduce the impact of uneven airflow distribution in the large PECVD chamber on the deposited film. At the same time, the special design of the inclined laminar flow plate surrounding the gas distribution plate makes it easier for the airflow to be dispersed to the surrounding area. This ensures the uniformity of airflow in each area of ​​the large chamber as much as possible, thereby further improving the uniformity of airflow distribution in the reaction chamber and thus improving the coating quality.

[0062] Furthermore, temperature detection components (not shown in the figure) are disposed around the heating component 16 to detect the temperature of the corresponding area within the carrier plate 11 or the reaction chamber 103. Optionally, the temperature detection components may also be distributed on the lower surface of the chamber cover 101 or the side wall of the chamber structure 1 to facilitate more accurate detection of the temperature distribution in different areas.

[0063] The control unit is electrically connected to the control valve 4, the temperature detection component, and the heating component 16, respectively. It sets the temperature of the heating component 16 according to the current coating temperature requirement within the reaction chamber 103, and adjusts the parameters of each control valve 4 based on the temperature detected by the temperature detection component, ensuring that the airflow uniformity differences in different areas within the reaction chamber 103 are within a preset range. For example, if the temperature of a certain area is detected to be lower than the set temperature of the heating component, it can be understood that the airflow in that area has affected the temperature (gas flow causes a certain degree of heat loss). Therefore, by detecting the temperature of different areas and comparing it with the set temperature of the heating component 16 (the reaction temperature required for the coating reaction), compensation is made by additionally adjusting the opening (flow rate) of the control valve 4.

[0064] Optionally, the temperature detection component in this embodiment of the invention is a patch-type temperature sensor. The patch-type temperature sensor is thin and can be directly attached to the lower surface or side wall of the carrier plate 11, without occupying space, and can reduce the turbulence effect on the airflow.

[0065] The PECVD system for depositing multiple film layers and featuring gas uniformity provided in this invention disperses and uniformly distributes the incoming gas by setting up a gas distribution box. Specifically, it controls the corresponding flow rate for different regions of the airflow, especially by appropriately compensating the reaction airflow in the peripheral area of ​​the chamber. At the same time, by detecting the temperature and combining it with the influence of temperature on the airflow, it achieves certain compensation for the airflow in the corresponding areas. In this way, it ensures the uniformity of airflow in each region of the large chamber as much as possible, thereby improving the uniformity of the deposited film layer and thus improving the quality and stability of the solar cell.

[0066] In some embodiments, the air distribution box 2 includes an upper air distribution plate 201, a lower air distribution plate 10, and an air inlet pipe assembly located on the upper surface of the upper air distribution plate 201. An air distribution plate 6 and a laminar flow plate 7 are disposed between the upper air distribution plate 201 and the lower air distribution plate 10. A first air inlet 501 is located at the center of the upper air distribution plate 201, i.e., the first air inlet 501 is located in the central air distribution area. Multiple second air inlets 502 are located around the upper air distribution plate 201, i.e., the second air inlets 502 are located in the peripheral air distribution areas. The air distribution plate 6 is located below the first air inlet 501 and is used to further disperse and distribute the airflow entering from the first air inlet 501, while also reducing the direct impact of the airflow on the workpiece surface, thus affecting the film formation quality. The laminar flow plate 7 is located below the second air inlets 502 and is used to further disperse and distribute the airflow entering from the second air inlets 502, while also reducing the direct impact of the airflow on the workpiece surface, thus affecting the film formation quality.

[0067] Optionally, there are four second air inlets 502, which are evenly distributed around the first air inlet 501. For example, the second air inlets 502 are located at the four vertices of a rectangle centered on the first air inlet 501, or arranged in a circular array on a circle centered on the first air inlet 501, which helps to improve the uniformity of airflow distribution inside the entire chamber.

[0068] Optionally, the ratio of the distance from the second air inlet 502 to the first air inlet 501 along the first direction to the distance from the first air inlet 501 to the side wall of the chamber is in the range of 2 / 5 to 3 / 5, preferably 1 / 2. This ensures that the airflow between the first air inlet 501 and the side wall of the chamber is compensated by the second air inlet 502 along the first direction, which is beneficial to improving the uniformity of airflow distribution in the entire chamber, thereby ensuring that the uniformity of single-plate coating (thickness distribution uniformity) is less than or equal to 5%.

[0069] Optionally, the ratio of the distance from the second air inlet 502 to the first air inlet 501 along the second direction to the distance from the first air inlet 501 to the side wall of the chamber is in the range of 2 / 5 to 3 / 5, preferably 1 / 2. This ensures that the airflow between the first air inlet 501 and the side wall of the chamber is compensated by the second air inlet 502 along the second direction, which is beneficial to further improve the uniformity of airflow distribution in the entire chamber and ensure that the uniformity of single-plate coating is less than or equal to 5%.

[0070] Furthermore, in this embodiment of the invention, an intake pipe assembly is provided to supply air to different areas. One end of the intake pipe assembly is connected to the intake pipe 20, and the other end is connected to the air inlet of different areas. Specifically, the intake pipe assembly includes: multiple branch pipes and corresponding control valves 4 disposed on the branch pipes. The first air inlet 501 and the second air inlet 502 are respectively connected to the corresponding branch pipes, and the flow rates of the first air inlet 501 and the second air inlet 502 are adjusted by the control valves 4 on the corresponding branch pipes.

[0071] Optionally, the gas equalization plate 6 is a disc structure, and the gas equalization plate 6 is provided with multiple gas equalization holes arranged in a circumferential array. The multiple gas equalization holes are arranged to form multiple rings with gradually changing diameters. The gas equalization holes on each ring are distributed in a circumferential array. The spacing between adjacent rings can be equal or can gradually increase from the center outward according to a certain rule.

[0072] Optionally, the number of laminar flow plates 7 is four. The four laminar flow plates 7 are evenly distributed around the gas distribution plate 6. The orthographic projection of the four laminar flow plates 7 on the lower gas distribution plate 10 forms an intermittent circular structure, that is, there is a certain gap between the four laminar flow plates 7, so that the gas flow velocity to the four corners is accelerated, thereby improving the airflow uniformity of the entire chamber.

[0073] Optionally, all four laminar flow plates 7 are inclined at a certain angle, with the side closer to the air distribution plate 6 being higher than the side farther from the air distribution plate 6. This makes it easier for the airflow to diffuse and flow to the surrounding area, which helps to further improve the uniformity of airflow distribution in the entire chamber.

[0074] Optionally, the angle between the laminar flow plate 7 and the horizontal plane (the plane where the gas equalization plate 6 is located) is 3°~8°, preferably 3°~5°. If the tilt angle is too large, it will increase the flow rate and turbulence of the surrounding gas, which will affect the uniformity of the coating. If the tilt angle is too small, it will result in poor dispersion of the airflow to the surrounding area.

[0075] Optionally, such as Figure 3 As shown, baffles 9 are respectively provided on both sides of the air distribution plate 6 along the first direction. The baffles 9 mainly play a certain role in separating the airflow in different areas to improve the uniform flow effect in different areas. The baffles 9 extend to the four laminar flow plates 7 at the two ends of the first direction, and a preset gap is left between the baffles 9 and the laminar flow plates 7; the first direction is the direction of one of the central symmetry lines of the air distribution box 2.

[0076] Optionally, the end of the baffle 9 is biased outward in the second direction along the first direction, so that an airflow diffuser is formed between the ends of the baffle 9 at the same end, and the airflow diffuser faces the discontinuous region along the second direction between two adjacent laminar flow plates 7; wherein, the second direction is the direction of another central symmetry line of the air distribution box 2, and the second direction is perpendicular to the first direction.

[0077] Optionally, the diffusion angle θ of the airflow diffuser is 60~120°, which is beneficial to the circulation and diffusion of airflow and further improves the uniformity of airflow distribution in the chamber.

[0078] In some embodiments, continue reading Figure 3 and Figure 4 The chamber cover 101 is also equipped with a third air inlet 503. The third air inlet 503 is a composite air inlet, and its upper end is connected to the air inlet pipe 20 and the cleaning pipe respectively. That is, during normal coating reaction, the valve (diaphragm valve) connected to the air inlet pipe is opened to achieve synchronous air intake with the first and second air inlets, which is more conducive to improving the uniformity of the reaction gas distribution in the entire chamber. When the chamber needs to be cleaned, the valve of the cleaning pipe 20 is opened and the valve of the air inlet pipe is closed. The airflow of the remote plasma source (RPS) is introduced into the cleaning pipe and enters the reaction chamber through the third air inlet 503. The gas distribution box 2 is also equipped with a cleaning flow equalization baffle 8, which is located below the third air inlet 503. There are two third air inlets 503. The two third air inlets 503 are symmetrically distributed on both sides of the first air inlet 501 along the second direction. The distance from the third air inlet 503 to the first air inlet 501 along the second direction is slightly smaller than the distance from the second air inlet 502 to the first air inlet 501 along the second direction, which is beneficial to improving cleaning efficiency and coating uniformity.

[0079] Optionally, the ratio of the distance from the third air inlet 503 to the first air inlet 501 along the second direction to the distance from the second air inlet 502 to the first air inlet 501 along the second direction is 1 / 3 to 4 / 5, preferably 1 / 2. This ensures that the distribution of the two third air inlets 503 along the first direction can basically cover the entire chamber area, thereby further improving the uniformity of the distribution of the reaction gas in the chamber and the cleaning effect of the chamber.

[0080] Optionally, the cleaning and equalizing baffle 8 is located on the side of the baffle 9 away from the air equalizing plate 6, and the cleaning and equalizing baffle 8 is directly opposite the discontinuous region along the first direction between two adjacent laminar flow plates 7.

[0081] Optionally, the lower air distribution plate 10 has multiple air outlets arranged in a linear array, which are distributed throughout the lower air distribution plate 10, thereby improving the airflow uniformity of the entire chamber space.

[0082] Optionally, the intake piping assembly includes a diaphragm valve 3. The diaphragm valve 3 is disposed on the connecting pipe between the control valve 4 and the intake pipe 20, and is used to control the opening or closing of the intake pipe 20. The diaphragm valve 3 achieves the opening or closing of the fluid by driving the diaphragm to contact or separate from the valve body sealing surface through the valve stem. It has good sealing performance, and the flow rate changes nearly linearly before about 60% of the stroke by adjusting the valve stem stroke, making it suitable for fine flow control. In addition, the diaphragm valve 3 also has the advantage of corrosion resistance, making it suitable for fluid control switching in the coating chamber of PECVD.

[0083] The PECVD system with gas uniformity function for depositing multiple film layers provided in this invention embodiment is equipped with corresponding gas distribution boxes for different reaction chambers. The gas distribution boxes disperse and uniformly distribute the airflow. Specifically, based on the uniformity of the previous coating, the airflow flow rate of the corresponding area is controlled separately for different areas. In particular, appropriate airflow compensation is performed for the surrounding area of ​​the chamber to reduce the impact of uneven airflow distribution in the large PECVD chamber on the deposited film layer. At the same time, the special design of the inclined laminar flow plate surrounding the gas uniformity plate makes it easier for the airflow to be dispersed to the surrounding area, thus ensuring the uniformity of airflow in each area of ​​the large chamber as much as possible. Furthermore, by setting a cleaning flow uniformity baffle and a baffle plate between the gas uniformity plate and the laminar flow plate, and the inclined laminar flow plate and the gas uniformity plate working together to form a special flow uniformity channel, and with the cooperation of diaphragm valve and control valve to control the airflow magnitude, the uniformity of airflow distribution in the reaction chamber is further improved, which is more conducive to improving the uniformity of the coated film layer, thereby improving the quality and stability of the solar cell.

[0084] Optionally, such as Figure 5 As shown, the PECVD system for depositing multiple film layers and having a gas equalization function further includes: an exhaust channel 19; an exhaust control valve 4 is provided on the exhaust channel 19, and a flow equalization screen (not shown in the figure) covering the exhaust channel 19 is provided on the bottom 102 of the chamber. The flow equalization screen is provided with multiple mesh holes, which can ensure the smooth flow of air and also prevent the film layers attached in the chamber from falling off and causing blockage of the exhaust channel 19.

[0085] Optionally, exhaust intake notches are provided at the four corners below the heating element 16. The exhaust intake notches can increase the flow speed of air to the four corners, thereby improving exhaust efficiency and airflow uniformity.

[0086] In some embodiments, continue reading Figure 5An air baffle assembly is provided between the carrier plate 11 and the cavity bottom 102. The air baffle assembly has a semi-closed annular structure. Since the airflow distribution in the central area is relatively large, while the airflow distribution around the cavity is relatively small, the air baffle assembly can accelerate the flow rate of the process gas in the four corners of the cavity, thereby making the gas flow more uniform and improving the coating uniformity.

[0087] Optionally, such as Figures 5 to 7 As shown, the air baffle assembly includes: a movable baffle 12, a flexible baffle 13, and a fixed baffle 14.

[0088] Specifically, the movable baffle 12 is fixed around the bottom of the heating component 16, thereby surrounding the bottom of the heating component 16. The fixed baffle 14 is disposed on the cavity bottom 102 and surrounds the lower edge of the movable baffle 12. A preset gap is left between the fixed baffle 14 and the movable baffle 12, which reduces the channel gap when residual gas is exhausted, making the exhaust more uniform along the length and width of the heating plate. Here, the length and width of the heating plate refer to the side length area of ​​the heating plate excluding the four corners.

[0089] The flexible baffle 13 is disposed between the heating component 16 and the cavity bottom 102, and is located inside the movable baffle 12. The flexible baffle 13 is provided with gas confluence ports at the four corners of the cavity structure 1. Its function is to increase the gap between the exhaust channels in the four corner areas of the heating plate, resulting in a faster exhaust speed compared to the side length area. The plasma can also diffuse more easily to the four corners, which is beneficial to improving the airflow uniformity of the entire cavity.

[0090] Optionally, the PECVD system for depositing multiple film layers and having a gas equalization function further includes: a lifting mechanism; the lifting mechanism includes a lifting rod 17 and a driving mechanism 18; the driving mechanism 18 is located below the cavity bottom 102, one end of the lifting rod 17 is connected to the driving mechanism 18, and the other end passes through the cavity bottom 102 and is connected to the bottom of the heating component 16, thereby driving the heating component 16 to rise to achieve rapid heating of the carrier plate 11.

[0091] Optionally, a frame 15 is provided below the bottom of the cavity structure 1 to support the cavity structure, thereby providing space for the installation of the lifting mechanism and the exhaust channel 19.

[0092] Based on the same inventive concept, such as Figure 8 As shown, this embodiment of the invention also provides a coating method, which employs the PECVD system described in the foregoing embodiments. The coating method includes:

[0093] S1. Feeding and preheating: The silicon wafers are placed on the carrier plate 11 and stacked into multiple layers; a batch is conveyed to the stacking lifting mechanism of the wafer feeding preheating cavity for preheating.

[0094] S2. Coating: The preheated multilayer carrier plates 11 are transported in batches to the first process chamber, and a first film layer is deposited on the carrier plates 11 through a one-stop deposition method. Then, the multilayer carrier plates 11 are transported in batches to the isolation chamber for gas washing and vacuuming, and then transported in batches to the second process chamber, and a second film layer is deposited on the carrier plates 11 through a one-stop deposition method. This process is repeated for several layers of coating until the coating process is completed. When coating in any process chamber, the parameters of the corresponding control valve are adjusted according to the coating uniformity of the previous coating in the current process chamber.

[0095] It should be noted that during the coating process, for any given process chamber, the coating thickness after the previous reaction is measured. Since the coating uniformity indirectly characterizes the airflow distribution uniformity within the chamber to some extent, this provides a basis for adjusting the control valve 4 for airflow in different areas. Furthermore, the "one-stop deposition" in this embodiment refers to the silicon wafer directly completing all coating processes within a single process chamber, with multiple process chambers simultaneously completing the coating of the same film layer, distinguishing it from existing step-by-step coating equipment and processes.

[0096] S3, Cooling and Unloading: The coated carrier plates 11 are transported in batches to the stacking lifting mechanism of the cooling and unloading chamber for cooling. After cooling, they are transported to the unloading machine to unload the silicon wafers.

[0097] The coating method provided in this embodiment of the invention employs the PECVD system described in the preceding embodiments. During coating, corresponding gas distribution boxes are set up for different reaction chambers, and the airflow is dispersed and uniformly distributed by setting up the gas distribution boxes. Specifically, the airflow flow rate of the corresponding area is controlled for the airflow in different areas. In particular, the airflow is appropriately compensated for in the surrounding area of ​​the chamber to reduce the impact of uneven airflow distribution in the large PECVD chamber on the deposition film on the surface of the solar cell silicon wafer. At the same time, by detecting the temperature and combining the effect of temperature on airflow, the airflow in the corresponding area is compensated to a certain extent. This ensures the uniformity of airflow in each area of ​​the large chamber as much as possible, which helps to improve the uniformity of the coating film and thus improve the quality and stability of the solar cell.

[0098] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. In the description of this specification, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A PECVD system for depositing multiple film layers and possessing a gas uniformity function, used to fabricate heterojunction solar cells, the PECVD system comprising a preheating chamber for wafer entry, a one-stop coating module, and a cooling and exiting chamber connected sequentially by gate valves, the one-stop coating module comprising an isolation chamber and several process chambers for depositing different film layers, characterized in that, The process chamber includes: A cavity structure, the cavity structure including a cavity cover, a cavity bottom and a reaction chamber located between the cavity cover and the cavity bottom, wherein a carrier plate for supporting the workpiece is disposed in the reaction chamber; An air distribution box is disposed between the cavity cover and the carrier plate. The air distribution box is divided into a central air distribution area and a peripheral air distribution area. The airflow in the central air distribution area and the peripheral air distribution area is controlled by corresponding control valves to adjust the airflow rate in the corresponding area. The air distribution box includes an upper air distribution plate, a lower air distribution plate, and an air inlet pipe assembly located on the upper surface of the upper air distribution plate. An air equalization plate and multiple laminar flow plates are arranged between the upper air distribution plate and the lower air distribution plate. The air equalization plate is located in the central air equalization area, and the multiple laminar flow plates are respectively located in the peripheral air equalization areas and surround the air equalization plate. The laminar flow plates are all inclined at a certain angle, and the edge near the air equalization plate is higher than the edge away from the air equalization plate. The control unit is electrically connected to the control valve and is used to adjust the parameters of the corresponding control valve according to the uniformity of the previous coating in the current process chamber. The upper air distribution plate has a first air inlet at its center and multiple second air inlets around its perimeter. The air distribution plate is located below the first air inlet, and the laminar flow plate is located below the second air inlets. There are four laminar flow plates, evenly distributed around the air distribution plate. The four laminar flow plates, when projected onto the lower air distribution plate, form a discontinuous circular structure. The air distribution plate has baffles on both sides along a first direction, extending from both ends of the baffles to the corresponding positions of the four laminar flow plates, with a predetermined gap between them. The ends of the baffles extend outwards along the first direction towards a second direction, forming airflow diffusers between the ends of the baffles at the same end. These diffusers face the discontinuous area along the second direction between two adjacent laminar flow plates. The second direction is the direction of another central symmetry line of the air distribution box.

2. The PECVD system for depositing multiple film layers and having a gas uniformity function according to claim 1, characterized in that, Also includes: A heating element is disposed at the bottom of the carrier plate and is used to heat the carrier plate and the reaction chamber. A temperature detection component is disposed around the heating component and is used to detect the temperature of the corresponding area; The control unit is connected to the temperature detection component and the heating component respectively, and is used to set the temperature of the heating component according to the current coating temperature requirement in the process chamber, and adjust the parameters of the corresponding control valve according to the detected temperature compensation.

3. The PECVD system for depositing multiple film layers and having a gas uniformity function according to claim 2, characterized in that, One end of the intake pipe assembly is used to connect to the intake pipe. The intake pipe assembly includes: multiple branch pipes and corresponding control valves disposed on the branch pipes. The first intake port and the second intake port are respectively connected to the corresponding branch pipes, and the first intake port and the second intake port are adjusted by the control valves on the corresponding branch pipes.

4. The PECVD system for depositing multiple film layers and having a gas uniformity function according to claim 3, characterized in that, The ratio of the distance from the second air inlet to the first air inlet along the first direction to the distance from the first air inlet to the side wall of the chamber is in the range of 2 / 5 to 3 / 5. The ratio of the distance from the second air inlet to the first air inlet along the second direction to the distance from the first air inlet to the side wall of the chamber is in the range of 2 / 5 to 3 / 5; wherein, the first direction is the direction of one of the central symmetry lines of the air distribution box, and the second direction is the direction of the other central symmetry line of the air distribution box.

5. The PECVD system for depositing multiple film layers and having a gas uniformity function according to claim 3, characterized in that, The gas equalization plate has a disc structure and multiple gas equalization holes arranged in a circumferential array. The multiple gas equalization holes are arranged to form multiple rings with gradually changing diameters.

6. The PECVD system for depositing multiple film layers and having a gas uniformity function according to claim 3, characterized in that, The diffusion angle of the airflow diffuser is 60~120°.

7. The PECVD system for depositing multiple film layers and having a gas uniformity function according to claim 3, characterized in that, The cavity cover is also provided with a third air inlet, the upper end of which is connected to the air inlet pipe and the cleaning pipe respectively; The cleaning pipe is used to introduce a remote plasma source gas flow into the reaction chamber when the chamber needs to be cleaned. The gas distribution box is also equipped with a cleaning flow equalization baffle, which is located below the third air inlet.

8. The PECVD system for depositing multiple film layers and having a gas uniformity function according to claim 7, characterized in that, The ratio of the distance from the third air inlet to the first air inlet along the second direction to the distance from the second air inlet to the first air inlet along the second direction is between 1 / 3 and 4 / 5.

9. The PECVD system for depositing multiple film layers and having a gas uniformity function according to claim 7, characterized in that, The cleaning flow equalization baffle is located on the side of the baffle away from the air equalization plate, and is directly opposite the discontinuous region along the first direction between two adjacent laminar flow plates.

10. The PECVD system for depositing multiple film layers and having a gas uniformity function according to claim 3, characterized in that, The lower air distribution plate has multiple air outlets, which are arranged in a linear array.

11. The PECVD system for depositing multiple film layers and having a gas uniformity function according to claim 3, characterized in that, The intake piping assembly includes a diaphragm valve; the diaphragm valve is disposed on the connection pipe between the control valve and the intake piping, and is used to control the opening and closing of the intake piping.

12. The PECVD system for depositing multiple film layers and having a gas uniformity function according to any one of claims 2 to 11, characterized in that, Also includes: Exhaust passage; An exhaust control valve is provided on the exhaust channel, and a flow equalization screen covering the exhaust channel is provided on the bottom of the cavity, with multiple mesh holes on the flow equalization screen.

13. The PECVD system for depositing multiple film layers and having a gas uniformity function according to claim 12, characterized in that, An air-blocking assembly is provided between the carrier plate and the bottom of the cavity. The air-blocking assembly has a semi-closed annular structure and is used to delay the airflow around the air-blocking assembly from being discharged from the exhaust channel.

14. The PECVD system for depositing multiple film layers and having a gas uniformity function according to claim 13, characterized in that, The air-blocking assembly includes: a movable baffle, a flexible baffle, and a fixed baffle; The movable baffle is fixed around the bottom of the heating component, and the fixed baffle is disposed on the bottom of the cavity and surrounds the lower edge of the movable baffle, with a preset gap between the fixed baffle and the movable baffle. The flexible baffle is disposed between the heating component and the cavity bottom, and is located inside the movable baffle. The flexible baffle is provided with gas inlets at the four corners of the cavity structure.

15. The PECVD system for depositing multiple film layers and having a gas uniformity function according to claim 12, characterized in that, Also includes: Lifting mechanism; The lifting mechanism includes a lifting rod and a drive mechanism; The drive mechanism is located below the bottom of the cavity. One end of the lifting rod is connected to the drive mechanism, and the other end passes through the bottom of the cavity and is connected to the bottom of the heating component.

16. A coating method employing the PECVD system as described in any one of claims 2-15, characterized in that, The coating method includes: S1. Feeding and preheating: Silicon wafers are placed on the carrier plate and stacked into multiple layers; a batch is conveyed to the stacking lifting mechanism of the wafer feeding preheating cavity for preheating; S2. Coating: The preheated multilayer carrier plates are transported in batches to the first process chamber, and the first film layer is deposited on the carrier plates through a one-stop deposition method. Then, the multilayer carrier plates are transported in batches to the isolation chamber for gas washing and vacuuming, and then transported in batches to the second process chamber, where the second film layer is deposited on the carrier plates through a one-stop deposition method. This process is repeated for several layers until the coating process is completed. When coating in any process chamber, the parameters of the corresponding control valve are adjusted according to the uniformity of the previous coating in the current process chamber. S3. Cooling and Unloading: The coated carrier boards are transported in batches to the stacking lifting mechanism of the cooling and unloading chamber for cooling. After cooling, they are transported to the unloading machine to unload the silicon wafers.

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