PECVD (plasma enhanced chemical vapor deposition) coating system and coating process

Abstract

The invention provides a PECVD (Plasma Enhanced Chemical Vapor Deposition) coating system which comprises a first deposition cavity used for placing a graphite boat loaded with a silicon wafer; the graphite boat comprises a plurality of boat pieces which are sequentially arranged in the first direction, the surfaces of the boat pieces are parallel to the second direction, and the silicon wafers are sequentially loaded between the adjacent boat pieces in the second direction; the first direction intersects with the second direction; the first deposition cavity is also provided with an air inlet piece, a heating piece and an electrode; wherein the process special gas is blown to the silicon wafer loaded in the graphite boat along a second direction through the gas inlet piece; the heating piece is arranged between the gas inlet piece and the graphite boat and is used for providing heat for the process special gas blown to the silicon wafer; the electrode is electrically connected with the graphite boat and is used for carrying out electrolytic ionization on the process special gas to generate plasma; the invention provides a PECVD (Plasma Enhanced Chemical Vapor Deposition) coating system and a PECVD coating process, aiming at solving the problems of low coating quality and uniformity of an existing coating mode.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic production technology, and in particular to a PECVD coating system and coating process. Background Art

[0002] In the field of solar cell preparation, in order to improve the photoelectric conversion efficiency and appearance quality of photovoltaic cells, it is usually necessary to deposit functional film layers on the surface of silicon wafers, such as passivation films, anti-reflection films, etc.

[0003] The functional film layer can be formed by deposition using a plasma enhanced chemical vapor deposition (PECVD) device or the like.

[0004] However, existing PECVD coating equipment is generally tubular PECVD or plate PECVD, and the coating quality needs to be further improved. Summary of the invention

[0005] The technical problem to be solved by the present application is to provide a PECVD coating system and a PECVD coating process to solve the coating quality problem of the existing coating method.

[0006] In order to solve the above problems, the present application is implemented through the following technical solutions:

[0007] The present application proposes a PECVD coating system, comprising a first deposition chamber for placing a graphite boat loaded with silicon wafers; the graphite boat comprises a plurality of boats arranged at intervals along a first direction, the surface of the boats is parallel to a second direction, and the silicon wafers on each boat are arranged along a third direction; the first direction and the second direction intersect; the third direction is parallel to the surface of the boats and perpendicular to the second direction;

[0008] The first deposition chamber is also provided with an air inlet, a heating element and an electrode; wherein the air inlet is used to blow the process gas toward the silicon wafer loaded in the graphite boat along the second direction; the heating element is provided between the air inlet and the graphite boat, and is used to provide heat to the process gas blown toward the silicon wafer;

[0009] The electrode is electrically connected to the graphite boat to electrolyze the process gas to generate plasma.

[0010] Optionally, the length direction of the first deposition chamber is parallel to the third direction, the height direction of the first deposition chamber is parallel to the second direction, and the gas inlet blows the process gas from the top of the first deposition chamber to the silicon wafer loaded in the graphite boat;

[0011] The electrode penetrates into the first deposition chamber from the top of the first deposition chamber along the second direction, and is electrically connected to the boat sheet of the graphite boat in the first deposition chamber.

[0012] Optionally, the width direction of the first deposition chamber is parallel to the first direction, and a plurality of graphite boats may be placed in sequence along the width direction of the first deposition chamber.

[0013] Optionally, the first deposition chamber has an inlet for the graphite boat to enter, and an outlet for the graphite boat to exit, and a direction from the inlet to the outlet is parallel to a length direction of the first deposition chamber.

[0014] Optionally, the PECVD coating system further comprises a first preheating chamber and a first cooling chamber, wherein the first preheating chamber, the first deposition chamber and the first cooling chamber are connected in sequence;

[0015] The PECVD coating system also includes a conveying mechanism, which can convey the graphite boat between the first preheating chamber, the first deposition chamber and the first cooling chamber.

[0016] Optionally, a flipping mechanism is further included, wherein the flipping mechanism is used to flip the silicon wafer after being coated in the first deposition chamber and place it in the graphite boat.

[0017] Optionally, the PECVD coating system further includes a second deposition chamber, wherein the first deposition chamber is used to coat one side of the silicon wafer, and the second deposition chamber is used to coat the other side of the silicon wafer.

[0018] Optionally, the PECVD coating system further includes a second preheating chamber and a second cooling chamber, and the second preheating chamber, the second deposition chamber and the second cooling chamber are connected in sequence.

[0019] Optionally, the first deposition chamber, the first preheating chamber, the first cooling chamber and the second deposition chamber, the second cooling chamber and the second preheating chamber are stacked up and down respectively.

[0020] Optionally, the flipping mechanism is disposed between the first cooling chamber and the second preheating chamber, and is used to flip the silicon wafers in the graphite boat transferred from the first cooling chamber.

[0021] Optionally, the conveying mechanism is disposed at the bottom of the first deposition chamber and / or the second deposition chamber, and is used to convey the graphite boat in the first deposition chamber and / or the second deposition chamber.

[0022] Optionally, a flow equalizing member is provided between the air inlet member and the graphite boat, and the process special gas is blown toward the silicon wafers loaded in the graphite boat through the flow equalizing member via the air inlet member along the second direction to equalize the flow of the process special gas introduced through the air inlet member.

[0023] Optionally, the first deposition chamber and / or the second deposition chamber is a square chamber.

[0024] The present application also provides a PECVD coating process, including:

[0025] Placing a graphite boat in a PECVD coating system, wherein the graphite boat comprises a plurality of boat plates arranged at intervals along a first direction, the surfaces of the boat plates are parallel to a second direction, and the silicon wafers on each boat plate are arranged along a third direction; the first direction and the second direction intersect; the third direction is parallel to the surface of the boat plates and perpendicular to the second direction;

[0026] A process gas is introduced into the PECVD coating system, and the process gas is blown toward the silicon wafer loaded in the graphite boat along a second direction;

[0027] The process special gas blown toward the silicon wafer is electrolyzed to generate plasma to form a film layer on the surface of the silicon wafer.

[0028] Compared with the prior art, this application has the following advantages:

[0029] The PECVD coating system in the present application shortens the flow path of the special gas by making the process special gas flow from one end of the silicon wafer to the other end of the silicon wafer, and the special gas is directly blown to the silicon wafer. At the same time, it can also greatly improve the uniformity of the special gas, thereby improving the uniformity of the film thickness and the coating quality.

[0030] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the chamber structure provided in an embodiment of the present application;

[0032] Figure 2 A three-dimensional diagram of a chamber provided in an embodiment of the present application;

[0033] Figure 3 A first angle cross-sectional view of a chamber provided in an embodiment of the present application;

[0034] Figure 4 A second angle cross-sectional view of the chamber provided in an embodiment of the present application;

[0035] Figure 5 A schematic diagram of the overall structure of the PECVD coating system provided in the embodiment of the present application;

[0036] Figure 6 A schematic diagram of the first coating process provided in an embodiment of the present application;

[0037] Figure 7A schematic diagram of a second coating process provided in an embodiment of the present application;

[0038] Figure 8 A schematic diagram of a third coating process provided in an embodiment of the present application;

[0039] Fig. 9 A schematic diagram of the first coating state provided in an embodiment of the present application;

[0040] Fig.10 A schematic diagram of a second coating state provided in an embodiment of the present application; DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0042] It should be understood that the references to "one embodiment" or "an embodiment" throughout the specification mean that the specific features, structures, or characteristics associated with the embodiment are included in at least one embodiment of the present application. Therefore, the references to "in one embodiment" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. In addition, these specific features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0043] PECVD equipment is a photovoltaic process equipment that can be used to prepare SiNx anti-reflection layers, polycrystalline silicon layers, amorphous silicon layers and other film layers on photovoltaic cells. Existing PECVD equipment is generally tubular or plate-type. When the process gas for coating in tubular equipment is introduced, it flows from one end of the tube mouth to the other end of the tube tail. The flow path of the process gas is the length of the furnace tube, which makes the path too long. The uniformity of the gas is affected to a certain extent, resulting in low coating quality and uniformity. In addition, the number of graphite boats loaded in a single coating process of tubular equipment is limited, and it cannot be flexibly transported and moved. The plate-type equipment uses a carrier plate to load silicon wafers. The silicon wafers are laid flat on the carrier plate. The number of loaded silicon wafers is limited, and the overall production efficiency is low.

[0044] In view of the above problems, the present application embodiment provides a PECVD coating system 100, such as Figure 1As shown, it includes a first deposition chamber 12 for placing a graphite boat 200 loaded with silicon wafers 90; the graphite boat 200 includes a plurality of boat sheets 201 arranged at intervals along a first direction, the surface of the boat sheet 201 is parallel to the second direction, and the silicon wafers 90 on each boat sheet 201 are arranged along a third direction, and are inserted between the boat sheets 201 of the graphite boat 200 in groups of two or inserted between the boat sheets 201 of the graphite boat 200 in a single piece for coating; the first direction intersects with the second direction; the third direction is parallel to the surface of the boat sheet 201 and is perpendicular to the second direction; the first deposition chamber 12 is also provided with an air inlet 50, a heating element 40 and an electrode 44; wherein the air inlet 50 is used to blow the process special gas along the second direction toward the silicon wafers 90 loaded in the graphite boat 200; the above-mentioned process special gas is a gas for film formation by deposition reaction, for example, when the above-mentioned equipment is used to make silicon nitride film, the above-mentioned process special gas can be silane gas. By blowing the special gas directly toward the silicon wafer 90 in the graphite boat 200 along the direction parallel to the placement direction of the silicon wafer 90 (the second direction), the special gas directly acts on the silicon wafer 90 and flows from one end of the silicon wafer 90 to the other end, shortening the flow path of the special gas, and at the same time greatly improving the uniformity of the special gas, thereby improving the uniformity of the film thickness. In the embodiment of the present application, the film formed by the coating process can be an anti-reflection film, a passivation film, etc., the anti-reflection film is a silicon nitride film, etc., and the passivation film is an aluminum oxide film, etc.

[0045] In the embodiment of the present application, the distance that the process special gas flows through the graphite boat 200 is the distance from the top to the bottom of the graphite boat 200, which can be specifically 200 to 300 mm, for example 240 mm. In the prior art, the special gas in the tubular vapor deposition equipment enters from the pipe mouth, flows out from the pipe tail, and flows from the bow to the stern of the graphite boat 200. Therefore, the process distance of the special gas in the present application is approximately 1 / 10 of the special gas flow distance of the tubular vapor deposition equipment, and the flow field uniformity and flow rate are significantly better than those of the tubular equipment. The flow rate can be increased by 98% compared with the tubular equipment, saving 49.5% of the special gas usage. The heating element 40 is disposed between the air inlet 50 and the graphite boat 200, and is used to provide heat to the process gas blown toward the silicon wafer 90 through the air inlet 50, so that the reaction gas can be heated to the reaction temperature after entering the chamber, and can also provide a heat source for the first deposition chamber 12 to ensure the temperature of the first deposition chamber 12 during the coating reaction; optionally, in one embodiment, the heating element 40 can be configured as a plurality of heating tubes, such as a first heating tube 41, a second heating tube 42 and a third heating tube 43; the first heating tube 41 It is arranged at the top of the chamber so that the reaction gas can be heated to the reaction temperature after entering the chamber, thereby improving the uniformity of the coating; the second heating tube 42 is arranged between the transmission shaft 32 and the bottom wall of the chamber, and can heat the silicon wafer 90 in the graphite boat 200 from the bottom side, and the third heating tube 43 is suspended between adjacent graphite boats 200 and between the graphite boat 200 and the side wall of the chamber, and can heat the silicon wafer 90 in the graphite boat 200 from the side, thereby ensuring the uniformity of the overall temperature and further improving the coating quality.

[0046] The electrode 44 is electrically connected to the graphite boat 200 to electrolyze the process gas to generate plasma. Optionally, in one embodiment, the electrode 44 penetrates into the first deposition chamber 12 along the second direction and is electrically connected to the boat sheet 201 of the graphite boat 200 in the first deposition chamber 12. The boat sheets 201 of two adjacent graphite boats 200 are connected to electrodes 44 of different polarities to coat the silicon wafer 90 in the placement groove between the boat sheets 201 of the graphite boat 200. Specifically, the boat sheets 201 of any two adjacent graphite boats 200 can be connected to electrodes 44 of different polarities, so as to ensure a higher electrode sheet carrying capacity and improve work efficiency. At the same time, under high-frequency conditions, no power loss will be generated at the rear end and the front end of the graphite boat 200. By directly connecting the boat sheet 201 of the graphite boat 200 along a direction (second direction) parallel to the placement direction of the silicon wafer 90, the electromagnetic field distribution of the boat sheet 201 of the graphite boat 200 can be made more uniform, thereby avoiding the problems of standing wave power loss and uneven electromagnetic field distribution at the front or rear end of the graphite boat 200.

[0047] Optionally, in one embodiment, Figures 2-3As shown, a flow equalizing member 52 is further provided between the air inlet member 50 and the graphite boat 200. The process special gas is blown through the flow equalizing member along the second direction through the air inlet member 50 toward the silicon wafer 90 loaded in the graphite boat 200, so as to equalize the flow of the process special gas introduced through the air inlet member 50. This can further improve the uniformity of the coating, facilitate the adjustment of the process parameters to ensure the uniformity of the film thickness, and eliminate the need to subsequently adjust the temperature compensation film thickness at different deposition positions, thereby avoiding the problem that multiple variables make it difficult to adjust the process parameters and ultimately affect the coating quality. In addition, the air inlet 50 blows directly to the silicon wafer 90 between the boat slices 201 of the graphite boat 200, and provides the process gas for the first deposition chamber 12. At the same time, the first deposition chamber 12 is also provided with an exhaust member 60 for extracting the gas in the chamber, thereby forming a gas path that enters from the air inlet 50 and flows through the silicon wafer 90 and the graphite boat 200 and then flows out from the exhaust member; so that the process gas directly blown to the silicon wafer 90 by the air inlet 50 along the direction parallel to the placement direction of the silicon wafer 90 (the second direction) enters the graphite boat 200 from one end of the silicon wafer 90 and flows out from the inside of the graphite boat 200, and then is extracted by the exhaust member 60, and the process gas flow path is short, which can better ensure the uniformity of the gas. Optionally, in a specific embodiment, the exhaust member 60 includes a vacuum tube 61, which is arranged on the bottom wall of the chamber and connected to a vacuum pump, and the vacuum pump can extract the gas inside the precursor through the vacuum tube 61, thereby forming a vacuum environment in the chamber. Specifically, the vacuum pump may be a dry pump.

[0048] In one embodiment, Figure 5 As shown, the PECVD coating system 100 further includes a first preheating chamber 11 and a first cooling chamber 13. The first preheating chamber 11, the first deposition chamber 12 and the first cooling chamber 13 are sequentially connected, and the graphite boat 200 can be transferred between the first preheating chamber 11, the first deposition chamber 12 and the first cooling chamber 13. The silicon wafer 90 is coated by a coating method of preheating before vapor deposition and cooling after vapor deposition, which can effectively improve the coating efficiency and coating uniformity, thereby improving the coating quality.

[0049] Optionally, in one embodiment, Figure 5 As shown, the PECVD coating system further includes a flipping mechanism 91, which is used to flip the silicon wafer 90 after being coated in the first deposition chamber 12 and place it in the graphite boat 200. After the silicon wafer 90 is coated in the first deposition chamber 12, the flipping mechanism 91 such as a manipulator or a magnetic arm can be used to take the silicon wafer 90 out of the graphite boat 200 and flip it over, and then load it back into the graphite boat 200, thereby achieving coating on both the front and back sides of the silicon wafer 90 or inspection and transportation after coating.

[0050] Optionally, in one embodiment, Figure 5As shown, the PECVD coating system 100 further includes a second deposition chamber 22, wherein the first deposition chamber 12 is used to coat one side of the silicon wafer 90, and the second deposition chamber 22 is used to coat the other side of the silicon wafer 90. The silicon wafer 90 loaded in the graphite boat 200 is coated on the first side in the first deposition chamber 12; the first side is one of the front side and the back side, and the silicon wafer 90 can be coated on a single piece or multiple pieces at the same time; the graphite boat 200 can be one or more, and multiple graphite boats 200 can be coated at the same time; after the first side coating is completed by the first deposition chamber 12, the silicon wafer 90 loaded in the graphite boat 200 can be transferred to the second deposition chamber 22, and the second side coating is carried out in the second deposition chamber 22, which can not only efficiently complete the double-sided coating of the silicon wafer 90 in each graphite boat 200 in sequence, but also complete the double-sided coating of the silicon wafers 90 in multiple graphite boats 200 at the same time, thereby improving the coating efficiency and production capacity of the graphite boat 200.

[0051] Among them, the first surface is one of the front and back sides of the silicon wafer 90, and the second surface is the other of the front and back sides of the silicon wafer 90, that is, the first surface can be the front side and the second surface can be the back side, or the first surface can be the back side and the second surface can be the front side. The silicon wafer 90 loaded in the graphite boat 200 is coated on the first side in the first deposition chamber 12 of the PECVD coating system, and the first side is one of the front side and the back side. After the first side is coated, the silicon wafer 90 is transferred to the second deposition chamber 22 of the PECVD coating system for second side coating, and the second side is the other of the front side and the back side. According to the PECVD coating system having the first deposition chamber 12 and the second deposition chamber 22, the silicon wafer 90 is first loaded in the graphite boat 200 and is coated on the first side in the first deposition chamber 12, and then directly transferred to the second deposition chamber 22 for second side coating, so that the front and back side coating can be completed by using one production line, which can reduce the time for transferring materials, and at least one group of silicon wafers 90 of the graphite boat 200 can be coated at the same time in the coating process and transferred separately, thereby alleviating the problem of low coating efficiency of the existing coating method.

[0052] Optionally, in one embodiment, a conveying mechanism 30 is further included, and the conveying mechanism 30 is arranged at the bottom of the first deposition chamber 12 and / or the second deposition chamber 22. The first deposition chamber 12 and / or the second deposition chamber 22 include a feed port and a discharge port, and the conveying mechanism 30 is used to convey the graphite boat 200 from the feed port to the discharge port. In the embodiment of the present application, the first deposition chamber 12 and the second deposition chamber 22 can be used to accommodate the conveying mechanism 30. The conveying mechanism 30 can be a conveyor belt, etc., which is arranged at the bottom of the chamber of the first deposition chamber 12 and the second deposition chamber 22, and arranged along the feed port of the chamber toward the discharge port. The conveying mechanism 30 is used to carry and convey the graphite boat 200. It is only necessary to place the graphite boat 200 on the conveying mechanism 30, that is, the graphite boat 200 can be controlled to move from the feed port of the chamber to the discharge port, so as to realize the rapid entry and exit of the graphite boat 200, and then realize the rapid placement and removal of the silicon wafer 90. The direction from the feed port to the discharge port is the length direction of the first deposition chamber 12 and / or the second deposition chamber 22, and the graphite boat 200 can be transferred from the feed port to the discharge port along the length direction. With this arrangement, multiple graphite boats 200 can be placed along the width direction of the first deposition chamber 12 and / or the second deposition chamber 22, and transported along the length direction. After the silicon wafer 90 is loaded into the first deposition chamber 12 of the PECVD coating system by using the graphite boat 200 for first-side coating, it can be directly transferred to the second deposition chamber 22 by the conveying mechanism 30 to coat the silicon wafer 90 on the second side, thereby using one production line to complete the front and back coating of multiple groups of silicon wafers 90 in multiple graphite boats 200, which can reduce the time for transporting materials while improving the coating efficiency, alleviating the problem of low coating efficiency of the existing coating method. The above-mentioned conveying mechanism 30 can be configured to include a carrier plate 31 and a plurality of transmission shafts 32 arranged side by side; the carrier plate 31 is arranged on the transmission shaft 32 and driven to translate by the transmission shaft 32, the carrier plate 31 is used to place the graphite boat 200, that is, the carrier plate 31 is placed on the plurality of transmission shafts 32 arranged side by side, and the graphite boat 200 is placed flat on the carrier plate 31, the transmission shaft 32 is driven by a driving device (not shown) such as a motor, etc., and can drive the transmission shaft 32 to rotate, thereby driving the carrier plate 31 to move along the transmission shaft 32 from the feed port of the chamber to the discharge port of the chamber, so that the graphite boat 200 also translates from the feed port of the chamber to the discharge port of the chamber. The conveying mechanism 30 can also be directly configured in the form of a conveyor belt or a conveying trolley, and examples are not given here one by one, as long as the function of conveying the graphite boat 200 can be realized.

[0053] Optionally, in a specific embodiment, the carrying surface of the carrier plate 31 is a plane, which is used to carry a plurality of graphite boats 200 arranged in parallel, and can realize coating of silicon wafers 90 in a plurality of graphite boats 200 at a time, thereby significantly improving the coating efficiency. For example, along the direction perpendicular to the feeding direction, the carrier plate 31 can have 4 graphite boats 200 arranged in parallel, which greatly increases the output. Optionally, the PECVD coating system 100 also includes a second preheating chamber 21 and a second cooling chamber 23, and the second preheating chamber 21, the second deposition chamber 22 and the second cooling chamber 23 are connected in sequence, and the conveying mechanism 30 can convey the graphite boat 200 between the first preheating chamber 11, the first deposition chamber 12, the first cooling chamber 13, the second preheating chamber 21, the second deposition chamber 22 and the second cooling chamber 23. The first preheating chamber 11, the first deposition chamber 12, the first cooling chamber 13, the second preheating chamber 21, the second deposition chamber 22 and the second cooling chamber 23 are all independent chambers 10, the feed port of each chamber 10 is connected to the discharge port of the corresponding chamber 10, and the feed port of each chamber and the discharge port of each chamber and the adjacent chambers are provided with a gate valve 80 that can be opened and closed, that is, along the direction from feeding to discharging, the adjacent chambers 10 are controlled by raising and lowering the gate valve; wherein the preheating chamber is used to preheat the silicon wafer 90 to be coated; the deposition chamber is used to deposit a film layer on the silicon wafer 90, and the cooling chamber is used to cool the silicon wafer 90 Cooling and lowering the temperature; the flipping mechanism 91 is arranged between the first cooling chamber 13 and the second preheating chamber 21, and is used to flip the silicon wafer 90 in the graphite boat 200 transmitted from the first cooling chamber 13. In this embodiment, the flipping mechanism 91 automatically flips the silicon wafer 90 after one side coating treatment in the first deposition chamber 12 and places it in the graphite boat 200, and then connects the graphite boat 200 to send it into the second deposition chamber 22 for the other side coating treatment, so that the production line is used to realize the coating of the front and back sides of the silicon wafer 90, reducing the process of automatic material transportation, shortening the process time, and effectively improving production efficiency.

[0054] Optionally, each chamber 20 in the first preheating chamber 11 , the first deposition chamber 12 , the first cooling chamber 13 , the second preheating chamber 21 , the second deposition chamber 22 and the second cooling chamber 23 is provided with a heating element 40 , an air intake element 50 and an exhaust element 60 .

[0055] Optionally, in a specific embodiment, the flipping mechanism 91 includes a multi-axis manipulator with a suction cup, which is used to suck the silicon wafer 90 from the side, flip it, and then place it in the graphite boat 200.

[0056] In this specific embodiment, the silicon wafer 90 is placed in the graphite boat 200 by inserting it, which can significantly increase the loading capacity of the silicon wafer 90 of a single graphite boat 200, thereby increasing the number of silicon wafers 90 coated in a single time; at the same time, the multi-axis manipulator of the flipping mechanism 91 has a suction cup, so it can suck the silicon wafer 90 from the side to flip it and insert it into the graphite boat 200 again, so as to realize the rapid flipping of the silicon wafer 90. Among them, by setting a plurality of suction cups, it is possible to realize a single suction of a plurality of silicon wafers 90 for flipping operation. For example, if the number and position of the suction cups match the silicon wafers 90 in the graphite boat 200, the entire row of silicon wafers 90 in a single graphite boat 200 can be flipped at the same time, significantly improving the efficiency of transferring the silicon wafer 90 from the first deposition chamber 12 to the second deposition chamber 22 after flipping, thereby saving the overall process time.

[0057] In this embodiment, the second side of the silicon wafer 90 is coated by a coating method of preheating before vapor deposition and cooling after vapor deposition, and the first side is coated by the first preheating chamber 11, the first deposition chamber 12, and the first cooling chamber 13 respectively. The silicon wafer 90 after the first side coating is completed is turned over by the turning mechanism 91 and then directly coated on the second side, which can effectively improve the efficiency and uniformity of the coating on both sides, thereby improving the coating quality, and the following operation methods can be included:

[0058] When there is only one graphite boat 200, Figure 6 As shown, after the silicon wafer 90 in the graphite boat 200 completes the preheating treatment step in the first preheating chamber, the graphite boat 200 and the silicon wafer 90 are transferred to the first deposition chamber 12 for the vapor deposition treatment step, and then the graphite boat 200 and the silicon wafer 90 are transferred to the first cooling chamber for cooling treatment. After the process steps in the first cooling chamber 13 are completed, the silicon wafer 90 in the graphite boat 200 is turned over and then transferred to the second preheating chamber to complete the preheating treatment on the other side of the silicon wafer 90, and then the vapor deposition treatment step in the second deposition chamber 22 and the cooling treatment step in the second cooling chamber are sequentially performed, thereby completing the coating on both sides of the silicon wafer 90.

[0059] When the number of the graphite boats 200 is at least two, one of them, such as Figure 7As shown, after all the graphite boats 200 and silicon wafers 90 are simultaneously placed in the first preheating chamber to complete the preheating treatment step, they are all simultaneously transferred to the first deposition chamber 12 for the vapor deposition treatment step, and finally they are all simultaneously transferred to the first cooling chamber for cooling treatment. After the process steps in the first deposition chamber 12 are completed, all the silicon wafers 90 in the graphite boats 200 are turned over and then all are transferred to the second preheating chamber to complete the preheating treatment of the other side of all the silicon wafers 90, and then the vapor deposition treatment step in the second deposition chamber 22 and the cooling treatment step in the second cooling chamber are carried out in turn, thereby completing the coating on both sides of all the silicon wafers 90 in the graphite boats 200 at the same time. Secondly, all the graphite boats 200 can also be placed in batches in each process chamber for process operations, for example, divided into three batches, as shown in Figure 8, the first batch first completes the preheating treatment in the first preheating chamber, and then is transferred to the first deposition chamber 12 for vapor deposition treatment. When the first batch of graphite boats 200 and silicon wafers 90 enter the first deposition chamber 12 for vapor deposition treatment, the second batch of graphite boats 200 and silicon wafers 90 enter the first preheating chamber to complete the preheating treatment, and so on...Therefore, the silicon wafers 90 in different graphite boats 200 can go through different batches and perform different process operations in different process chambers at the same time. It can be seen from the two operation methods as shown in the above examples that the present application can not only greatly shorten the entire process time but also improve production capacity by overlapping the process time of each process section and accommodating multiple groups of graphite boats 200 for simultaneous operation.

[0060] In this specific embodiment, independent chambers are used to perform preheating, vapor deposition and cooling processes respectively, and adjacent batches of silicon wafers 90 are placed in different chambers to perform corresponding processes, which can achieve overlapping process times of adjacent batches of silicon wafers 90, reduce the time when the chamber is idle or the silicon wafers 90 wait for the process, thereby shortening the entire coating process time and improving production capacity. If only one graphite boat 200 needs to coat the silicon wafer 90, the silicon wafer 90 enters the preheating chamber for preheating treatment, and the preheating chamber is evacuated to a vacuum environment; at this time, the vapor deposition chamber is always kept in a vacuum environment; when the vapor deposition is completed and the cooling process is entered, the vacuum is broken in the cooling process chamber, thereby effectively avoiding interference and pollution from impurity gases, thereby ensuring the uniformity of coating. In addition, if multiple groups of graphite boats 200 are being coated at the same time, the multiple groups of graphite boats 200 can be preheated in the preheating chamber at the same time, or the multiple groups of graphite boats 200 can be coated in batches in sequence. At this time, the graphite boat 200 in the preheating chamber, the graphite boat 200 in the vapor deposition chamber, and the graphite boat 200 in the cooling chamber can be preheated, vapor deposited, and cooled at the same time respectively. Similarly, the vacuuming operation in the preheating chamber, the vacuuming in the vapor deposition chamber, and the vacuum breaking operation in the cooling chamber can also be performed at the same time, thereby overlapping the preheating, vapor deposition, and cooling treatments, and even the vacuuming time and process time, greatly shortening the entire process time, thereby improving production capacity.

[0061] Optionally, in one embodiment, the processing time of the preheating, vapor deposition and cooling treatments is 12 to 18 minutes, for example, each can be one of 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes or a range value between any two of them.

[0062] Optionally, in one embodiment, the processing time of the above-mentioned preheating, vapor deposition and cooling treatments is controlled to be the same, which can minimize the time the chamber is idle or the time the silicon wafer waits for the process. For example, the processing time of the above-mentioned preheating, vapor deposition and cooling treatments is controlled to be 15 minutes, and the total duration of the coating process is the process time + the transmission and discharging time. The process time is 15 minutes, and the transmission and discharging time is 1 minute, then the total duration is 16 minutes; while in the prior art, the silicon wafer is placed in the same tubular equipment chamber to coat a layer of SiNx film, and the process flow of preheating, vapor deposition and cooling in sequence takes nearly 40 minutes; by comparison, it can be seen that the coating method provided in the embodiment of the present application can greatly shorten the entire process time.

[0063] In the embodiment of the present application, the above-mentioned first deposition chamber 12, first preheating chamber 11, first cooling chamber 13 and the second deposition chamber 22, second cooling chamber 23 and second preheating chamber 21 can be designed as a double-layer structure, or arranged in parallel as a double-row structure, or connected end to end to be arranged as a ring structure, all of which can achieve the use of one production line to complete the front and back side coating of the silicon wafer 90, reducing the automated transportation of materials.

[0064] Optionally, in one embodiment, Figure 5 As shown, the first deposition chamber 12, the first preheating chamber 11, the first cooling chamber 13, the second deposition chamber 22, the second cooling chamber 23 and the second preheating chamber 21 are stacked up and down respectively, so that after coating one side of the silicon wafer 90, the silicon wafer 90 in the graphite boat 200 can be automatically turned over and then directly enter the process section of coating the other side. For example, after the positive film is made in the first deposition chamber 12 and cooled in the first cooling chamber 13, the silicon wafer 90 in the graphite boat 200 is automatically turned over, directly enters the second preheating chamber 21 for preheating and enters the second deposition chamber 22 to make the back film, which reduces the process steps of introducing the silicon wafer 90 in the graphite boat 200 into the flower basket, then transferring through the flower basket, and then introducing the silicon wafer 90 in the flower basket into the graphite boat 200, thereby improving production efficiency.

[0065] Optionally, in another specific embodiment, the coating device 100 further includes a material picking and placing device 92, which is used to automatically introduce silicon wafers from the basket into the carrier and then send them to the first process chamber 11, and introduce silicon wafers that have been coated in the second process chamber 12 from the carrier into the basket. The material picking and placing device 92 can also be a multi-axis manipulator with a suction cup.

[0066] Optionally, in one embodiment, the first deposition chamber 12 and / or the second deposition chamber 22 is a square chamber, and a rectangular or quasi-rectangular structure with a length, width and height is formed by adopting the chamber design of a plate-type vapor deposition device, so that the length direction of the first deposition chamber 12 and / or the second deposition chamber 22 is parallel to the first direction, the height direction of the first deposition chamber 12 and / or the second deposition chamber 22 is parallel to the second direction, and the width direction of the first deposition chamber 12 and / or the second deposition chamber 22 is parallel to the third direction, that is, at this time, the first deposition chamber 12 and the second deposition chamber 22 are both square chambers, and multiple graphite boats 200 are transported from the feed port to the discharge port along the length direction of the first deposition chamber 12 and / or the second deposition chamber 22, and preheating, deposition and cooling are performed in sequence, and double-sided coating of the first surface and the second surface is completed. At the same time, multiple graphite boats 200 can be placed in sequence along the width direction of the first deposition chamber 12 and / or the second deposition chamber 22, and the conveying mechanism 30 can also carry multiple graphite boats 200 loaded with silicon wafers 90, and can translate the graphite boats 200 from the feed port to the discharge port. Therefore, by conveying multiple graphite boats 200 and blowing the process special gas directly to the silicon wafers 90, the gas transmission path during the coating process is shortened, the gas flow uniformity and the coating quality are improved, and the number of silicon wafers 90 coated in a single time can be increased, and the silicon wafers 90 are convenient to ship. It can effectively take into account the advantages of plate-type vapor deposition equipment and tube-type vapor deposition equipment, alleviate the problem of low coating efficiency of the existing PECVD coating system 100, and also enable the above-mentioned PECVD coating system 100 to save floor space. Compared with conventional plate deposition equipment that coats by laying out silicon wafers 90 (silicon wafers are laid out on a carrier, which is inconvenient for silicon wafer transportation and the number of silicon wafers that can be carried by the carrier is limited), the above-mentioned coating equipment coats by carrying silicon wafers 90 on a graphite boat 200. Multiple graphite boats 200 can be placed in the coating equipment to increase the number of silicon wafers 90 that can be coated at one time. In addition, due to the small footprint of the graphite boat 200, multiple graphite boats 200 can be placed side by side / in parallel in the coating equipment at the same time in the same space, which greatly improves the coating rhythm. A tubular coating device placed in a tubular cavity for coating, the coating device can realize the transmission of the graphite boat 200 in the cavity or between cavities by setting a conveying mechanism 30, and can also place multiple graphite boats 200 side by side / in parallel, thereby increasing the carrying capacity of the graphite boat 200 and the silicon wafer 90 during the coating process, and also having greater process flexibility; specifically, based on the measurement of 4 graphite boats 200 entering at a time, the land area is reduced by 15% compared with the existing 6-tube equipment, the land area per GW can be reduced by 43%, and the comprehensive equipment investment per GW is reduced by 11% compared with the 6-tube equipment.

[0067] Optionally, in one embodiment, the process gas passes through the gas inlet 50 along the second direction, blows from the top of the first deposition chamber 12 to the silicon wafer 90 loaded in the graphite boat 200, and flows into the exhaust member from the bottom of the graphite boat 200; the exhaust member is arranged at the bottom of the first deposition chamber 12 and is located below the conveying mechanism 30, so that the process gas in the chamber 10 enters the graphite boat 200 from the top and exits from the bottom of the graphite boat 200, and is then extracted by the exhaust member, and the process gas flow path is short, which is conducive to the adjustment of process parameters to ensure the uniformity of film thickness, and there is no need to subsequently adjust the temperature compensation film thickness at different deposition positions, avoiding the problem that multiple variables make it difficult to adjust process parameters and ultimately affect the coating quality. Among them, in one embodiment, the carrier plate 31 is provided with uniformly arranged first uniform flow holes 33, and the gas flow direction of the first uniform flow holes 33 is perpendicular to the plane where the carrier plate 31 is located, so that the gas can be quickly discharged; the shape of the first uniform flow holes 33 can be circular, square or regular polygonal, preferably circular.

[0068] The coating special gas is controlled to flow from the top of the graphite boat 200 to the bottom of the graphite boat 200. Specifically, the process special gas can be controlled to enter the graphite boat 200 from the top of the deposition chamber through the uniform flow plate, so as to be directly blown to the silicon wafer 90 in the graphite boat 200, and then out from the bottom of the graphite boat 200, and then extracted from the bottom of the deposition chamber by the vacuum pump. Therefore, compared with the single tube PECVD coating system, the ventilation from the feed port (tube port or plate port) and the exhaust from the discharge port (tube port or plate port) are more convenient. In the method of plate opening, the present application introduces special gas from the top of the graphite boat 200 and discharges the special gas from the bottom of the graphite boat 200, and blows it directly to the silicon wafer 90 in the graphite boat 200, shortening the flow path of the special gas, and at the same time greatly improving the uniformity of the special gas, thereby improving the uniformity of the film thickness. In addition, the electrode 44 penetrates into the first deposition chamber 12 from the top of the first deposition chamber 12 along the second direction, and is electrically connected to the boat sheet 201 of the graphite boat 200 in the first deposition chamber 12. By penetrating from the top and directly connecting to the boat sheet 201 of the graphite boat 200 along the direction (second direction) parallel to the placement direction of the silicon wafer 90, the electrical connection distance between the electrode 44 and the graphite boat 200 is shortened, avoiding the problem of standing wave power loss at the front or rear end of the graphite boat 200 and uneven distribution of the electromagnetic field.

[0069] When coating, Figure 5As shown, firstly, the silicon wafers 90 fed from the flower basket are introduced into the graphite boat 200 through the automated workstation, and then the gate valve 80 at the feed port of the first preheating chamber 11 is opened. After the graphite boat 200 enters the first preheating chamber 11, the gate valve 80 is closed, and vacuuming and preheating of the graphite boat 200 are started; after the preheating is completed, the gate valve 80 between the first preheating chamber 11 and the first deposition chamber 12 is opened, and the graphite boat 200 is transferred to the first deposition chamber 12; the vacuum environment is always maintained in the first deposition chamber 12, and the graphite boat 200 enters the first deposition chamber 12 from the first preheating chamber 11, and then the gate valve 80 between the first preheating chamber 11 and the first deposition chamber 12 is closed. 2, the deposition coating process can be performed; after the process is completed, the gate valve 80 between the first deposition chamber 12 and the first cooling chamber 13 is opened, the graphite boat 200 is transferred to the first cooling chamber 13, and then the gate valve 80 between the first deposition chamber 12 and the first cooling chamber 13 is closed, and at the same time, the first cooling chamber 13 starts to break the vacuum and cool the graphite boat 200, and after the cooling is completed, the gate valve 80 at the discharge port of the first cooling chamber 13 is opened, the graphite boat 200 can be transferred to the automated workstation, and then the gate valve 80 at the discharge port is closed, that is, vacuuming is started to cool the subsequent silicon wafers 90.

[0070] Among them, because the surface coating of the silicon wafer 90 needs to go through preheating, deposition and cooling processes in sequence, if all of them are carried out in the same chamber, it is necessary to perform vacuum deposition only after the preheating is completed, and wait for cooling and unloading from the boat after the deposition is completed before a new silicon wafer 90 can be sent in for coating. Multiple waiting steps are required, resulting in low overall production capacity of the equipment.

[0071] In the above-mentioned embodiment, the first preheating chamber 11, the first deposition chamber 12 and the first cooling chamber 13 are arranged in sequence and each chamber is independent of each other, so each chamber can perform a process independently, that is: after the graphite boat 200 is sent from the first preheating chamber 11 to the first deposition chamber 12 and the gate valve 80 between the first preheating chamber 11 and the first deposition chamber 12 is closed, a new graphite boat 200 can be sent into the first preheating chamber 11 and the silicon wafer 90 in the graphite boat 200 is preheated without waiting for the deposition of the silicon wafer 90 in the previous graphite boat 200; after the graphite boat 200 is sent from the first deposition chamber 12 to the first cooling chamber 13 and the gate valve 80 between the first cooling chamber 13 and the first deposition chamber 12 is closed, a new graphite boat 200 can be sent into the first deposition chamber 12 and the silicon wafer 90 in the graphite boat 200 is deposited and coated without waiting for the cooling of the silicon wafer 90 in the previous graphite boat 200. Therefore, the above implementation can significantly shorten the entire coating process time and can shorten the process time to 15 minutes, thereby improving production capacity.

[0072] Optionally, based on the PECVD coating system provided in the embodiment of the present application, during the entire coating process, only one graphite boat 200 loaded with silicon wafers 90 may sequentially enter each chamber to perform the corresponding coating process, as shown in FIG. Fig. 9 shown.

[0073] Optionally, based on the PECVD coating system provided in the embodiment of the present application, during the entire coating process, one or more graphite boats 200 loaded with silicon wafers 90 enter each chamber to perform corresponding coating processes, as shown in FIG. Fig.10 shown.

[0074] In view of the above problems, the present application further provides a PECVD coating process, comprising steps 101 to 103:

[0075] Step 101, placing a graphite boat 200 in a PECVD coating system, wherein the graphite boat 200 includes a plurality of boat plates 201 arranged at intervals along a first direction, the surface of the boat plates 201 is parallel to a second direction, and the silicon wafers 90 on each boat plate are arranged along a third direction; the first direction and the second direction intersect; the third direction is parallel to the surface of the boat plates 201 and perpendicular to the second direction;

[0076] Step 102, introducing a process gas into the PECVD coating system, wherein the process gas is blown toward the silicon wafer 90 loaded in the graphite boat 200 along a second direction;

[0077] Step 103 , electrolyzing the process gas blown toward the silicon wafer 90 to generate plasma, so as to form a film layer on the surface of the silicon wafer 90 .

[0078] In the above step 101 , the silicon wafers 90 may be inserted in pairs between the boat wafers 201 of the graphite boat 200 or inserted individually between the boat wafers 201 of the graphite boat 200 for coating.

[0079] In the above step 102, the process special gas is a gas for film formation by deposition reaction. For example, when the above device is used to make a silicon nitride film, the process special gas may be silane gas. The special gas is blown directly to the silicon wafer 90 in the graphite boat 200 in a direction parallel to the placement direction of the silicon wafer, directly acting on the silicon wafer 90 and flowing from one end of the silicon wafer 90 to the other end, shortening the flow path of the special gas and greatly improving the uniformity of the special gas, thereby improving the uniformity of the film thickness.

[0080] In the above step 103, by electrolyzing the process gas blown toward the silicon wafer 90 to generate plasma, the silicon wafer 90 in the placement groove between the boat slices 201 of the graphite boat 200 can be uniformly coated, thereby improving the coating quality.

[0081] Optionally, by connecting two adjacent graphite boat pieces 201 with electrodes of different polarities, the process gas blown toward the silicon wafer 90 can be electrolyzed to generate plasma, so as to coat the silicon wafer 90 in the placement groove between the boat pieces 201 of the graphite boat 200, thereby ensuring a higher carrying capacity of the silicon wafer 90 and improving work efficiency; at the same time, under high-frequency conditions, no power loss will be generated at the rear end of the graphite boat 200 and the front end of the graphite boat 200. By directly connecting the boat pieces 201 of the graphite boat 200 along a direction (second direction) parallel to the placement direction of the silicon wafer 90, the electromagnetic field distribution of the boat pieces 201 of the graphite boat 200 can be made more uniform, thereby avoiding the problems of standing wave power loss and uneven electromagnetic field distribution at the front or rear end of the graphite boat 200.

[0082] In summary, in this embodiment, the PECVD coating system in the present application increases the number of silicon wafers coated in a single time, facilitates the shipment of silicon wafers, can effectively take into account the advantages of plate-type equipment and tube-type equipment, has a short flow path for process special gases, high gas uniformity, and good coating quality and uniformity.

[0083] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0084] Although the optional embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including optional embodiments and all changes and modifications that fall within the scope of the present application.

[0085] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity from another entity, and do not necessarily require or imply any such actual relationship or order between these entities. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that an article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such article or terminal device. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the article or terminal device including the elements.

[0086] The technical solution provided by the present application is introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. At the same time, for those skilled in the art, according to the principles and implementation methods of the present application, there may be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present application.

Claims

1. A PECVD coating system, characterized in that: The invention comprises a first deposition chamber for placing a graphite boat loaded with silicon wafers; the graphite boat comprises a plurality of boats arranged in intervals along a first direction, the surfaces of the boats are parallel to a second direction, and the silicon wafers on each boat are arranged along a third direction; the first direction and the second direction intersect; the third direction is parallel to the surface of the boats and perpendicular to the second direction; The first deposition chamber is also provided with an air inlet, a heating element and an electrode; wherein the air inlet is used to blow the process gas toward the silicon wafer loaded in the graphite boat along the second direction; the heating element is provided between the air inlet and the graphite boat, and is used to provide heat for the process gas blown toward the silicon wafer; The electrode is electrically connected to the graphite boat to electrolyze the process gas to generate plasma.

2. The PECVD coating system according to claim 1, characterized in that: The length direction of the first deposition chamber is parallel to the third direction, the height direction of the first deposition chamber is parallel to the second direction, and the gas inlet blows the process gas from the top of the first deposition chamber to the silicon wafer loaded in the graphite boat; The electrode penetrates into the first deposition chamber from the top of the first deposition chamber along the second direction, and is electrically connected to the boat sheet of the graphite boat in the first deposition chamber.

3. The PECVD coating system according to claim 1, characterized in that: The width direction of the first deposition chamber is parallel to the first direction, and a plurality of graphite boats may be placed in sequence along the width direction of the first deposition chamber.

4. The PECVD coating system according to any one of claims 1 to 3, characterized in that: The first deposition chamber has an inlet for the graphite boat to enter, and an outlet for the graphite boat to exit, and the direction from the inlet to the outlet is parallel to the length direction of the first deposition chamber.

5. The PECVD coating system according to any one of claims 1 to 3, characterized in that: The PECVD coating system further comprises a first preheating chamber and a first cooling chamber, wherein the first preheating chamber, the first deposition chamber and the first cooling chamber are connected in sequence; The PECVD coating system also includes a conveying mechanism, which can convey the graphite boat between the first preheating chamber, the first deposition chamber and the first cooling chamber.

6. The PECVD coating system according to claim 5, characterized in that: It also includes a turning mechanism, which is used to turn over the silicon wafer after being coated in the first deposition chamber and place it in the graphite boat.

7. The PECVD coating system according to claim 1, characterized in that: The PECVD coating system also includes a second deposition chamber, the first deposition chamber is used to coat one side of the silicon wafer, and the second deposition chamber is used to coat the other side of the silicon wafer.

8. The PECVD coating system according to claim 7, characterized in that: The PECVD coating system also includes a second preheating chamber and a second cooling chamber, and the second preheating chamber, the second deposition chamber and the second cooling chamber are connected in sequence.

9. The PECVD coating system according to claim 8, characterized in that: The first deposition chamber, the first preheating chamber, the first cooling chamber and the second deposition chamber, the second cooling chamber and the second preheating chamber are stacked up and down respectively.

10. The PECVD coating system according to claim 9, characterized in that: The flipping mechanism is arranged between the first cooling chamber and the second preheating chamber, and is used for flipping the silicon wafers in the graphite boat transported through the first cooling chamber.

11. The PECVD coating system according to claim 7, characterized in that: The conveying mechanism is arranged at the bottom of the first deposition chamber and / or the second deposition chamber, and is used for conveying the graphite boat in the first deposition chamber and / or the second deposition chamber.

12. The PECVD coating system according to claim 1, characterized in that: A flow equalizing member is also provided between the air inlet member and the graphite boat. The process special gas is blown toward the silicon wafers loaded in the graphite boat through the flow equalizing member along the second direction through the air inlet member to equalize the flow of the process special gas introduced through the air inlet member.

13. The PECVD coating system according to claim 7, characterized in that: The first deposition chamber and / or the second deposition chamber is a square chamber.

14. A PECVD coating process, characterized in that: include: Placing a graphite boat in a PECVD coating system, wherein the graphite boat comprises a plurality of boat plates arranged at intervals along a first direction, the surfaces of the boat plates are parallel to a second direction, and the silicon wafers on each boat plate are arranged along a third direction; the first direction and the second direction intersect; the third direction is parallel to the surface of the boat plates and perpendicular to the second direction; A process gas is introduced into the PECVD coating system, and the process gas is blown toward the silicon wafer loaded in the graphite boat along a second direction; The process special gas blown toward the silicon wafer is electrolyzed to generate plasma to form a film layer on the surface of the silicon wafer.

Images