Fluorine etching equipment based on non-plasma

Abstract

The invention relates to the technical field of semiconductor manufacturing, in particular to fluorine etching equipment based on non-plasma. The etching reaction cavity is arranged on the transmission path of the feeding transmission mechanism, a plurality of areas with different functions are arranged in the etching reaction cavity, the silicon wafer enters the cavity through the feeding transmission mechanism and then sequentially penetrates through the functional areas to obtain the etched silicon wafer, the whole process does not have pause and buffer processes, and the production efficiency is improved. The continuous production effect of reacting while moving is achieved, the total process time from entering the etching reaction cavity to leaving the etching reaction cavity ranges from dozens of seconds to several minutes, and the production efficiency is effectively improved. Besides, the air pressure in the etching reaction cavity is basically normal pressure, a nitrogen curtain is adopted to be isolated from the external atmospheric environment, a vacuum pump does not need to be used for pumping to a vacuum or low-pressure environment, the use of the vacuum pump is saved, and compared with the conventional closed cavity design, the simple equipment space design greatly reduces the manufacturing complexity and cost of the equipment.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor manufacturing, and in particular to a non-plasma-based fluorine etching device. Background Art

[0002] Solar cells are devices that convert solar energy into electrical energy. They can be divided into thin-film type and silicon wafer (chip) type. Silicon wafer type solar cells can be further divided into single crystal silicon wafer solar cells and multi-crystalline silicon wafer solar cells. By etching the silicon wafer, micro-nano structures can be formed on the surface, thereby enhancing the ability to absorb light and helping to improve the photoelectric conversion efficiency of solar cells. Since etching can help optimize the surface morphology of silicon wafers, thereby improving the output power and stability of photovoltaic cells, it is often necessary to etch the silicon substrate with various precise sizes during the production of solar cells. The range of etching agents includes liquid etching agents: such as ethylenediamine catechol (EDP) and KOH, and high-energy plasma etching agents based on Cl2 or SF6 gas. These etching agents can provide great flexibility and controllability in the manufacture of precisely defined microstructures, but because these etching agents are usually limited in selectivity to general materials used as mask layers (such as photoresists or oxides) in the etching process, the use of these etching agents is limited.

[0003] Non-plasma silicon etchants such as F2 can achieve a high etching rate of several μm / min for silicon materials at normal pressure, have high selectivity for photoresists, silicon oxides, silicon nitrides or aluminum layers, and can etch silicon in the gas phase. In addition, this etching method can quickly etch the surface of large-scale silicon structures, and because it can react at atmospheric pressure, it does not require a complex vacuum system and has potential application prospects.

[0004] For the current photovoltaic cell production that requires high production capacity (>8000 pieces / h), conventional high-energy plasma silicon wafer fluorine etching equipment does not meet the application needs of the photovoltaic industry at all due to its high equipment cost and low production capacity. Therefore, it is necessary to develop silicon wafer fluorine etching equipment for use in the photovoltaic cell production process to improve the production efficiency of photovoltaic cells and reduce production costs. Summary of the invention

[0005] Based on the problem that the silicon wafer fluorine etching equipment existing in the prior art cannot meet the efficient production requirements of photovoltaic cells, resulting in low efficiency and high production costs in the production process of photovoltaic cells, the present invention provides a non-plasma based fluorine etching equipment to overcome the above problems.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions: In a first aspect, the present invention provides a non-plasma-based fluorine etching device, comprising an etching reaction chamber and a loading and conveying mechanism, wherein air curtains are correspondingly arranged on opposite sides of the etching reaction chamber, the loading and conveying mechanism passes through the air curtains and runs through the etching reaction chamber, and a preheating zone, a process zone and a cooling zone are distributed in the etching reaction chamber along the extension direction of the loading and conveying mechanism, and the loading and conveying mechanism comprises at least one transmission track for transmitting silicon wafers.

[0007] The present invention sets an etching reaction chamber on the transmission path of the feeding transmission mechanism, and configures a plurality of areas with different functions in one etching reaction chamber. The feeding transmission mechanism passes through each functional area in turn. The two sides of the etching reaction chamber are separated from the external atmospheric environment by nitrogen curtains to form a relatively closed space. After the silicon wafer enters the etching reaction chamber, it is first preheated to the required reaction temperature in the preheating zone, and then continuously transmitted to the process zone for etching with the process gas reaction. After the reaction is completed, it is cooled in the cooling zone and then transmitted out of the etching reaction chamber. The whole process has no pause and buffering process, and the continuous production effect of moving and reacting is achieved. The total process time from entering the etching reaction chamber to exiting the etching reaction chamber is between tens of seconds and several minutes, which effectively improves the production efficiency. In addition, the air pressure in the etching reaction chamber is basically normal pressure, and the nitrogen curtain is used to isolate it from the external atmospheric environment. It does not need to be pumped to a vacuum or low-pressure environment by a vacuum pump, which saves the use of a vacuum pump. The simple equipment space design greatly reduces the manufacturing complexity and cost of the equipment compared to the conventional closed chamber design.

[0008] Preferably, the transmission track is any one of a roller transmission track, a belt transmission track, a chain transmission track, and a conveyor belt transmission track.

[0009] Preferably, the loading and conveying mechanism further comprises a plurality of carriers arranged on the conveying track for placing silicon wafers.

[0010] The carrier can be a basket, tray, or boat with a silicon wafer clamping mechanism or a silicon wafer installation slot. The silicon wafers are stacked or laid flat in the carrier. During transmission, the surface of the silicon wafer is parallel or perpendicular to the transmission direction. To further improve the etching processing efficiency of the silicon wafer, the carrier can also be set to a multi-layer structure that can hold multiple layers of silicon wafers. The transmission track is not limited to only one transmission, but can be two or more parallel tracks, so that the loading transmission mechanism can simultaneously transmit multiple rows or columns of carriers.

[0011] Preferably, a flipping mechanism for flipping the silicon wafer is provided in the etching reaction chamber.

[0012] In order to realize double-sided reactive etching of silicon wafers in the same reactive etching chamber, a flipping mechanism for flipping silicon wafers can be set in the etching reaction chamber. For example, the preheating zone, process zone or cooling zone can be set to more than one respectively, such as the first preheating zone-first process zone-second preheating zone-second process zone-cooling zone, and each zone is separated by an air curtain. The first surface of the silicon wafer is reactively etched in the first process zone, the second surface of the silicon wafer is reactively etched in the second process zone, and the silicon wafer is flipped in the second preheating zone, so that double-sided reactive etching of the silicon wafer can be realized in the same reactive etching chamber.

[0013] Preferably, an exhaust gas treatment device is further included, and the etching reaction chamber is provided with an exhaust port for exhausting the gas in the etching reaction chamber, and the exhaust port is connected to the exhaust gas treatment device.

[0014] Preferably, the exhaust ports are respectively provided on the etching reaction chambers in the process zone close to the preheating zone and the cooling zone.

[0015] In order to further discharge the excess process gas and reaction product gas in the process zone and avoid leakage into the preheating zone and the cooling zone, the exhaust port is arranged at the junction of the preheating zone and the cooling zone on both sides of the process zone and closer to one side of the process zone.

[0016] Preferably, the etching reaction chamber comprises an etching reaction inner chamber and an etching reaction outer chamber arranged outside the etching reaction inner chamber.

[0017] Preferably, a plurality of gas injection ports for injecting purge gas, dilution gas or process gas into the etching reaction cavity are arranged on the inner cavity wall of the etching reaction cavity.

[0018] When the silicon wafer is transported in a manner parallel to the horizontal plane, the process gas is injected from one or both sides of the side of the chamber, and the process gas flows through the surface of each layer of the silicon wafer to cause reactive etching; when the silicon wafer is transported in a manner perpendicular to the horizontal plane, the process gas is injected from one or both sides of the top or bottom surface of the chamber, and the process gas flows through the surface of each layer of the silicon wafer to cause reactive etching.

[0019] Preferably, the arrangement of the gas injection ports on the cavity wall corresponds to the arrangement of the silicon wafers in the carrier, that is, each row of gas injection ports is substantially flush with the silicon wafers, and an exhaust port is also correspondingly arranged on the cavity wall opposite to the gas injection ports.

[0020] The injected gas can directly flow into the silicon wafer surface through the gas injection port to produce an etching reaction, and then the residual gas and reaction gaseous products are discharged through the exhaust port on the opposite side cavity wall. Since the airflow has a short distance and is evenly distributed on the silicon wafer surface, a consistent etching effect can be achieved.

[0021] Preferably, the etching reaction outer chamber is provided with a negative pressure detection device for detecting whether the etching reaction outer chamber is a micro-negative pressure environment, and a special gas detector for detecting whether there is gas leakage in the etching reaction outer chamber.

[0022] When the etching equipment is working, a slightly negative pressure environment is maintained in the outer chamber. Even if a leak occurs in the inner chamber, due to a certain pressure difference between the outer chamber and the outside world, the etching gas will not leak into the environment and can be discharged to the exhaust gas treatment device through the exhaust port.

[0023] Preferably, the surfaces of the mechanisms in contact with the process gas in the fluorine etching equipment are all provided with a fluorine-resistant etching coating, and the fluorine-resistant etching coating includes one or more of polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkoxy ether copolymer, fluorinated ethylene propylene, ethylene and tetrafluoroethylene copolymer, and ethylene and chlorotrifluoroethylene polymer.

[0024] Compared with the prior art, the present invention has the following beneficial effects: The present invention sets an etching reaction chamber on the transmission path of the feeding transmission mechanism, and configures a plurality of areas with different functions in one etching reaction chamber. After the silicon wafer enters the chamber through the feeding transmission mechanism, it passes through each functional area in turn to obtain a silicon wafer that has been etched. The whole process has no pause and buffering process, and a continuous production effect of moving and reacting is achieved. The total process time from entering the etching reaction chamber to exiting the etching reaction chamber is between tens of seconds and several minutes, which effectively improves production efficiency. In addition, the air pressure in the etching reaction chamber is basically normal pressure, and a nitrogen curtain is used to isolate it from the external atmospheric environment. It does not need to be pumped to a vacuum or low-pressure environment with a vacuum pump, which saves the use of a vacuum pump. The simple equipment space design greatly reduces the manufacturing complexity and cost of the equipment compared to the conventional closed chamber design. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only part of the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 This is a schematic diagram of the overall structure of the fluorine etching equipment.

[0027] Figure 2 This is a schematic diagram of the structure of the fluorine etching equipment containing a transmission track.

[0028] Figure 3 This is a schematic diagram of the structure of the fluorine etching equipment containing two transmission tracks.

[0029] Figure 4 This is a schematic diagram of the structure of the flipping mechanism included in the fluorine etching equipment.

[0030] Figure 5 This is a schematic diagram of the structure in which the gas injection port and the exhaust port in the fluorine etching equipment are arranged relative to each other.

[0031] Among them: etching reaction chamber 1, etching reaction inner chamber 1-1, etching reaction outer chamber 1-2, feeding transmission mechanism 2, transmission track 21, carrier 22, air curtain 3, preheating area 4, process area 5, cooling area 6, turning mechanism 7, exhaust gas treatment device 8, exhaust port 9, gas injection port 10, negative pressure detection device 11, special gas detector 12. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments of the specification. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0033] The drawings of this specification are schematic diagrams, which assist in explaining the concept of the present invention and schematically show the shapes of various parts and their mutual relationships. Please note that in order to clearly show the structures of various components of the embodiments of the present invention, the drawings are not drawn to the same scale, and the same reference numerals are used to represent the same parts.

[0034] As shown in Figures 1 to 5, the non-plasma-based fluorine etching equipment in this embodiment includes an etching reaction chamber 1 and a loading and conveying mechanism 2. Air curtains 3 are correspondingly arranged on the opposite sides of the etching reaction chamber 1. The loading and conveying mechanism 2 passes through the air curtain 3 and penetrates the etching reaction chamber 1. A preheating zone 4, a process zone 5 and a cooling zone 6 are distributed in the etching reaction chamber 1 along the extension direction of the loading and conveying mechanism 2. The loading and conveying mechanism 2 includes at least one transmission track 21 for transmitting silicon wafers. By setting an etching reaction chamber 1 on the transmission path of the loading and conveying mechanism 2, and configuring multiple areas with different functions in one etching reaction chamber 1, the loading and conveying mechanism 2 passes through each functional area in turn, and the two sides of the etching reaction chamber 1 are separated from the external atmospheric environment by the nitrogen curtain 3 to form a relatively closed space. After the silicon wafer enters the etching reaction chamber 1, it is first preheated to the required reaction temperature in the preheating zone 4, and then continuously transmitted to the process zone 5 to react with the process gas for etching. After the reaction is completed, it is cooled in the cooling zone 6 and then transmitted out of the etching reaction chamber 1. The whole process has no pause and buffering process, and the continuous production effect of moving and reacting is achieved. The total process time from entering the etching reaction chamber 1 to exiting the etching reaction chamber 1 is between tens of seconds and several minutes, which greatly improves the production efficiency. In addition, the air pressure in the etching reaction chamber 1 is basically normal pressure, and the nitrogen curtain 3 is used to isolate it from the external atmospheric environment. It is not necessary to use a vacuum pump to evacuate to a vacuum or low-pressure environment, which saves the use of a vacuum pump. The simple equipment space design greatly reduces the manufacturing complexity and cost of the equipment compared to the conventional closed chamber design. The preheating zone 4 may be heated by infrared or hot air circulation, and the cooling zone 6 may be cooled by cold air.

[0035] The transmission track 21 is any one of a roller transmission track, a belt transmission track, a chain transmission track, and a conveyor belt transmission track. The loading transmission mechanism 2 also includes a plurality of carriers 22 for placing silicon wafers arranged on the transmission track 21. The carrier 22 can be a basket, a tray, or a boat with a silicon wafer clamping mechanism or a silicon wafer mounting slot. The silicon wafers are stacked or laid flat in the carrier 22. During transmission, the surface of the silicon wafer is parallel or perpendicular to the transmission direction. In order to further improve the etching processing efficiency of the silicon wafer, the carrier 22 can also be set as a multi-layer structure that can hold multiple layers of silicon wafers. The transmission track 21 is not limited to only one transmission, and can be two or more parallel tracks, so that the loading transmission mechanism 2 can simultaneously transmit multiple rows or columns of carriers 22.

[0036] A flipping mechanism 7 for flipping the silicon wafer is provided in the etching reaction chamber 1. In order to realize double-sided reactive etching of the silicon wafer in the same reactive etching chamber, a flipping mechanism 7 for flipping the silicon wafer can be provided in the etching reaction chamber 1. For example Figure 4As shown: the preheating zone 4, the process zone 5 or the cooling zone 6 can be arranged to be more than one respectively, for example, the first preheating zone 4-first process zone 5-second preheating zone 4-second process zone 5-cooling zone 6 is arranged, and each area is separated by an air curtain 3. The first surface of the silicon wafer is reactively etched in the first process zone 5, and the second surface of the silicon wafer is reactively etched in the second process zone 5. The silicon wafer is flipped in the second preheating zone 4, so that double-sided reactive etching of the silicon wafer can be achieved in the same reactive etching chamber.

[0037] The etching equipment further includes an exhaust gas treatment device 8, and an exhaust port 9 for exhausting the gas in the etching reaction chamber 1 is provided on the etching reaction chamber 1, and the exhaust port 9 is connected to the exhaust gas treatment device 8. In order to further exhaust the excess process gas and reaction product gas in the process zone 5 to avoid leakage into the preheating zone 4 and the cooling zone 6, exhaust ports 9 are respectively provided on the etching reaction chamber 1 in the process zone 5 near the preheating zone 4 and the cooling zone 6, that is, the exhaust ports 9 are arranged in the areas where the two sides of the process zone 5 intersect with the preheating zone 4 and the cooling zone 6, and are closer to one side of the process zone 5.

[0038] The etching reaction chamber 1 includes an etching reaction inner chamber 1 - 1 and an etching reaction outer chamber 1 - 2 disposed outside the etching reaction inner chamber 1 - 1 .

[0039] The inner cavity wall of the etching reaction cavity 1-1 is provided with a plurality of gas injection ports 10 for injecting purge gas, dilution gas or process gas into the etching reaction cavity 1-1. When the silicon wafer is transported in a manner parallel to the horizontal plane, the process gas is injected from one or both sides of the side of the cavity, and the process gas flows through the surface of each layer of the silicon wafer to cause reactive etching; when the silicon wafer is transported in a manner perpendicular to the horizontal plane, the process gas is injected from one or both sides of the top or bottom surface of the cavity, and the process gas flows through the surface of each layer of the silicon wafer to cause reactive etching.

[0040] As an implementation method, Figure 5As shown, the arrangement of the gas injection ports 10 on the cavity wall corresponds to the arrangement of the silicon wafers in the carrier 22, that is, each row of gas injection ports 10 is substantially flush with the silicon wafers, and an exhaust port 9 is also correspondingly arranged on the cavity wall on the side opposite to the gas injection ports 10. In this way, the injected gas can flow directly into the surface of the silicon wafer through the gas injection ports 10 to undergo an etching reaction, and then the residual gas and reaction gaseous products are discharged through the exhaust ports 9 on the opposite cavity wall. Since the gas flow has a short stroke and is evenly distributed on the surface of the silicon wafer, a consistent etching effect can be achieved. In some embodiments, the gas can flow through the gas injection ports 10 and the exhaust ports 9 on the cavity wall to form a circulation path, that is, the exhausted gas is collected and processed through a pipeline and then enters the gas injection ports 10 on the cavity wall on the side where the gas is injected, and enters the etching reaction chamber 1 for an etching reaction, which can improve the utilization efficiency of the process gas and reduce production costs. In addition, the gas injection port 10 and the exhaust port 9 are not limited to small holes, gaps or gas diffusion plates. Their shapes and arrangements are preferably designed to achieve uniform dispersion of gas injection. For example, in some embodiments, the process gas at the gas injection port 10 can be injected through the gaps or pores on the wall of the etching reaction cavity 1-1. The gaps or pores can be arranged in the form of multiple rows, multiple columns or cross-shaped gaps to improve the uniformity of the contact between the gas and the silicon wafer.

[0041] The etching reaction outer chamber 1-2 is provided with a negative pressure detection device 11 for detecting whether the etching reaction outer chamber 1-2 is a micro-negative pressure environment, and a special gas detector 12 for detecting whether there is a gas leak in the etching reaction outer chamber 1-2. When the etching equipment is working, the outer chamber maintains a micro-negative pressure environment. Even if the inner chamber leaks, the etching gas will not leak into the environment due to a certain pressure difference between the outer chamber and the outside world, and can be discharged to the exhaust gas treatment device 8 through the exhaust port.

[0042] The surfaces of the mechanisms in contact with the process gas in the fluorine etching equipment are all provided with an anti-fluorine etching coating, and the anti-fluorine etching coating includes one or more of polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkoxy ether copolymer, fluorinated ethylene propylene, ethylene and tetrafluoroethylene copolymer, and ethylene and trifluorochloroethylene polymer.

[0043] The method for etching a silicon wafer using the fluorine etching equipment comprises the following steps: S1, placing a plurality of carriers 22 loaded with silicon wafers on the transmission track 21 in sequence, and transmitting the carriers 22 to the etching reaction chamber 1 in sequence through the transmission track 21; S2, the silicon wafer transferred into the chamber: preheated to the temperature required by the process in the preheating zone 4 in the etching reaction chamber 1, the preheating temperature is generally 50-300°C, preferably 80-260°C; the process gas is introduced into the process zone 5 to perform etching reaction on the silicon wafer, and the temperature of the process zone 5 is always maintained within a certain range, which belongs to the constant temperature zone; the carrier 22 and the silicon wafer that has completed the etching reaction are cooled in the cooling zone 6, and then the silicon wafer is transferred to the next station for the next step of the process; Among them, the process gas is F2.

Claims

1. A non-plasma based fluorine etching apparatus, characterized in that: The invention comprises an etching reaction chamber (1) and a loading and conveying mechanism (2), wherein air curtains (3) are correspondingly arranged on opposite sides of the etching reaction chamber (1), the loading and conveying mechanism (2) passes through the air curtains (3) and penetrates the etching reaction chamber (1), and a preheating zone (4), a process zone (5) and a cooling zone (6) are distributed in the etching reaction chamber (1) along the extension direction of the loading and conveying mechanism (2), and the loading and conveying mechanism (2) comprises at least one conveying track (21) for conveying silicon wafers.

2. The non-plasma based fluorine etching apparatus according to claim 1, characterized in that: The transmission track (21) is any one of a roller transmission track, a belt transmission track, a chain transmission track, and a conveyor belt transmission track.

3. The non-plasma based fluorine etching apparatus according to claim 1 or 2, characterized in that: The loading and conveying mechanism (2) further comprises a plurality of carriers (22) arranged on the conveying track (21) for placing silicon wafers.

4. The non-plasma based fluorine etching apparatus according to claim 1, characterized in that: A turning mechanism (7) for turning over the silicon wafer is arranged in the etching reaction chamber (1).

5. The non-plasma based fluorine etching apparatus according to claim 1 or 4, characterized in that: It also comprises an exhaust gas treatment device (8), and the etching reaction chamber (1) is provided with an exhaust port (9) for exhausting the gas in the etching reaction chamber (1), and the exhaust port (9) is connected to the exhaust gas treatment device (8).

6. The non-plasma based fluorine etching apparatus according to claim 5, characterized in that: The exhaust ports (9) are respectively arranged on the etching reaction chambers (1) in the process zone (5) close to the preheating zone (4) and the cooling zone (6).

7. The non-plasma based fluorine etching apparatus according to claim 1, characterized in that: The etching reaction chamber (1) comprises an etching reaction inner chamber (1-1) and an etching reaction outer chamber (1-2) arranged outside the etching reaction inner chamber (1-1).

8. The non-plasma based fluorine etching apparatus according to claim 7, characterized in that: A plurality of gas injection ports (10) for injecting purge gas, dilution gas or process gas into the etching reaction inner cavity (1-1) are arranged on the inner cavity wall of the etching reaction inner cavity (1-1).

9. The non-plasma based fluorine etching apparatus according to claim 7 or 8, characterized in that: The etching reaction outer chamber (1-2) is provided with a negative pressure detection device (11) for detecting whether the etching reaction outer chamber (1-2) is a micro-negative pressure environment, and a special gas detector (12) for detecting whether there is gas leakage in the etching reaction outer chamber (1-2).

10. The non-plasma based fluorine etching apparatus according to claim 1, characterized in that: The surfaces of the mechanisms in contact with the process gas in the fluorine etching equipment are all provided with fluorine-resistant etching coatings, and the fluorine-resistant etching coatings include one or more of polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkoxy ether copolymer, fluorinated ethylene propylene, ethylene and tetrafluoroethylene copolymer, and ethylene and chlorotrifluoroethylene polymer.

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