Method for transferring a silicon wafer while maintaining cleanliness

Abstract

The present application provides a kind of transfer method for keeping the cleanliness of silicon wafer, steps include: the wafer basket carrying silicon wafer is transported to trolley;From the trolley output to buffer station;From the trolley output to equipment;The trolley, the buffer station and the equipment are all provided with cavity for carrying the silicon wafer;The trolley is formed when the buffer station and the equipment are docked with the cavity, and the cavity in the cavity is the same as the cleanliness, temperature and humidity and air pressure, and all reach preset standard, control the wafer basket passes through the cavity.The present application can make the silicon wafer always in micro-positive pressure state and thousand level clean environment during the whole handling process, prevent the surface of silicon wafer from being contaminated by dust, improve the surface quality of silicon wafer, and can improve the silicon wafer yield by 0.5-0.8%.

Description

Technical Field

[0001] This invention belongs to the field of solar cell silicon wafer production technology, and in particular relates to a transfer method that can maintain the cleanliness of silicon wafers. Background Technology

[0002] In the current silicon wafer manufacturing process, all steps have very high requirements for the surface quality of the silicon wafers. However, the current silicon wafer handling is an open transport method, which cannot guarantee the surface quality of the silicon wafers. The silicon wafer surface is prone to dust adsorption, which causes the silicon wafer surface to be contaminated. Contaminated silicon wafers are prone to small black spots during texturing and coating, which reduces the conversion efficiency of the subsequent silicon wafers and seriously affects the product yield. Summary of the Invention

[0003] This invention provides a method for handling silicon wafers that maintains their cleanliness, particularly suitable for handling solar-grade silicon wafers during the manufacturing process, thus solving the technical problem in the prior art where silicon wafers are easily contaminated by dust during handling.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A method for transporting silicon wafers while maintaining their cleanliness includes the following steps:

[0006] The wafer basket containing the silicon wafers is transported to the transport trolley;

[0007] The output from the trolley is sent to the buffer station;

[0008] Output from the trolley to the device;

[0009] The trolley, the buffer station, and the device are all equipped with cavities for carrying the silicon wafers;

[0010] The trolley forms a sealed cavity when it docks with the buffer station and the equipment;

[0011] When the cleanliness, temperature, humidity, and air pressure of the cavity and the passage cavity in the trolley, the buffer station, and the device are all the same and all meet the preset standards, the tray is controlled to pass through the passage cavity.

[0012] Furthermore, the cleanliness standard is set at no more than 1,000 particles per cubic meter, and the particle size is no greater than 0.5 μm.

[0013] Furthermore, the temperature and humidity settings are as follows: temperature 21-26°C, humidity 40-60%.

[0014] The pressure setting standard is a slightly positive pressure state.

[0015] Furthermore, a docking position for docking with the trolley is provided at the connection between the buffer station and the trolley;

[0016] Automatic roller shutters are provided in alignment at the connection point, the trolley, and the buffer station.

[0017] Furthermore, in the connecting position, the trolley, and the buffer station, the tray can enter from the roller shutter door at one end and exit from the roller shutter door at the other end.

[0018] Furthermore, the connecting position, the trolley, and the buffer station are all equipped with a transfer track for placing the tray;

[0019] The transfer tracks in the connecting position, the trolley, and the buffer station are matched and connected to each other.

[0020] Furthermore, the connecting position, the trolley, and the buffer station are all equipped with FFU purifiers for filtering the air entering the cavity, and exhaust devices for ventilation are also provided.

[0021] Furthermore, each of the connecting position, the trolley, and the buffer station is equipped with a testing instrument for monitoring the temperature, humidity, cleanliness, and air pressure of the cavity.

[0022] Furthermore, the cache station includes several cache layers, and each cache layer has several cache storage bits, and each cache storage bit is a pair of interfaces; and the connection bit can be connected to any cache layer.

[0023] Furthermore, the device is also provided with a docking interface for the trolley, and the roller shutter door is also provided on the docking interface.

[0024] Furthermore, the device also includes an FFU purifier for purifying the air and a testing instrument for monitoring temperature, humidity, cleanliness, and air pressure.

[0025] The transfer method designed in this invention can ensure that silicon wafers are transported under a slightly positive pressure and in a Class 1000 clean environment throughout the entire handling process, preventing dust contamination of the silicon wafer surface, improving the surface quality of the silicon wafers, and increasing the yield of silicon wafers by 0.5-0.8%. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the coordination of related equipment in a transfer method for maintaining the cleanliness of silicon wafers according to an embodiment of the present invention.

[0027] In the picture:

[0028] 10. Carts; 20. Shuttle stations; 30. Buffer stations

[0029] 40. Equipment Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0031] This embodiment proposes a silicon wafer cleanliness transport method for controlling the handling of silicon wafers in a clean space during various processes in a production workshop. The main design includes a transport trolley 10, a wafer buffer station 30, and automated production equipment 40. A connection point 20 is provided at the connection between the buffer station 30 and the trolley 10. The specific structure is as follows: Figure 1 As shown, the steps include:

[0032] First, the wafer basket containing the silicon wafers is transported to the transport trolley 10;

[0033] Then it is output from the trolley 10 to the docking station 20, and then from the docking station 20 it is transported to the buffer station 30; or

[0034] The output can be directly from the trolley 10 to the device 40, or it can be transferred from the output of the buffer station 30 to the device 40 via the trolley 10.

[0035] The trolley 10, the docking station 20, the buffer station 30, and the equipment 40 are all equipped with cavities for carrying silicon wafers. During the transportation process, when the trolley 10 and the docking station 20, the trolley 10 and the equipment 40, and the docking station 20 and the buffer station 30 are connected, a sealed passage cavity is formed. Only when the cleanliness, temperature, humidity, and air pressure in the corresponding cavity and the corresponding passage cavity are the same and all meet the preset standards can the wafer basket be controlled to pass through the corresponding passage cavity.

[0036] Furthermore, the cleanliness standard is set at no more than 1,000 particles per cubic meter, and the particle size is no larger than 0.5 μm. This standard provides a thousand-level particle size environment for silicon wafer storage, thereby ensuring the quality of silicon wafer storage.

[0037] Accordingly, the temperature and humidity settings are: temperature 21-26℃, humidity 40-60%. Simultaneously, the air pressure setting is a slightly positive pressure state; that is, a dry air pressure difference slightly higher than the external atmospheric pressure is generated inside all cavities and passageways. This forces moisture, dust, and other pollutants from the external environment to prevent them from penetrating into the cavities and passageways, keeping the environment inside them clean and dry at all times. This prevents air leakage, protects the surface quality of the silicon wafers, and ensures the airtightness and safety of silicon wafer storage.

[0038] Specifically, the trolley 10 is a mobile device that can move and walk. It has a cavity for placing silicon wafers and a transfer track for carrying wafer baskets containing silicon wafers. The trolley 10 has movable wheels on its lower part and a navigation laser head and camera on its outer wall for navigation. The trolley 10 is guided to move in the workshop based on a preset travel distance and navigation recognition results, thereby moving the wafer baskets containing silicon wafers to the interface position of the buffer station 30 or the equipment 40.

[0039] To ensure the airtightness and cleanliness of the silicon wafers stored within the trolley 10, a filter is installed at the top of the trolley 10 to filter the air entering the cavity. Preferably, an FFU filter is selected, which can achieve a particle size of Class 1000 cleanliness within the cavity of the trolley 10, ensuring a clean environment for the silicon wafers and preventing dust from adhering to the wafer surface. Furthermore, to ensure the sealing of the cavity of the trolley 10 during wafer basket input or output, automatic roller shutters are required at both ends of the transfer track of the trolley 10. This isolates the cavity carrying the silicon wafers from the outside air. Whether feeding or discharging, when one end is open, the other end is closed. Moreover, when the wafer basket is being fed into or output from the cavity of the trolley 10, the automatic roller shutters can automatically detect the entry and exit dynamics of the wafer basket and quickly open or close to prevent outside air from entering the cavity.

[0040] In addition, in order to monitor whether the measured values ​​of temperature and humidity inside the cavity of the cart 10 meet the standards, a temperature and humidity tester needs to be installed inside the cart 10. When the temperature or humidity inside the cavity of the cart 10 does not meet the standards, dry air needs to be blown into the cavity or exhausted out through the exhaust device installed on the cart 10, so that the cavity inside the cart 10 can be suitable for storing the wafer basket containing silicon wafers.

[0041] Meanwhile, a particle size analyzer and a pressure analyzer for monitoring particle size should be installed in the cavity of the trolley 10, so as to cooperate with the temperature and humidity analyzer in real time to complete the monitoring of the storage environment in the cavity of the trolley 10, so that the silicon wafers can be placed and transported safely, continuously and stably.

[0042] Furthermore, since the cache station 30 can store a large number of wafer baskets carrying silicon wafers, it is equivalent to a cache transfer station. It includes several cache layers, and each cache layer has several cache storage bits. In order to ensure that the input and output of all cache storage bits are in the first-in-first-out order, each cache storage bit is equipped with a double pair of interfaces. At the same time, in order to better connect the wafer baskets downloaded from the mobile cart 10, a docking position 20 is required for turnover. That is, the docking position 20 is required to be able to move vertically up and down to dock with any cache layer, and after docking with the cart, it can move towards the side closer to the cache station 30 and dock with the cache storage bit of the corresponding layer. It is also required that the docking position 20 and the cache station 30 are independently set up and can automatically close the roller shutter door to form a closed cavity.

[0043] That is, similar to the trolley 10, the connecting position 20, the buffer station 30 and the production equipment 40 are all equipped with cavities for holding the silicon wafer baskets; and the connecting position 20, the buffer station and the equipment 40 are all equipped with aligned automatic roller shutters; that is, in the connecting position 20, the buffer station and the equipment 40, the wafer baskets can enter from the roller shutter at one end and exit from the roller shutter at the other end.

[0044] To ensure a clean environment at the handover points during silicon wafer transfer, a sealed cavity must be formed when the trolley 10 connects to the docking station 20, the trolley 10 connects to the equipment 40, and the docking station 20 connects to the buffer station 30. This ensures that the silicon wafer remains in a closed and clean environment throughout the entire transfer process, guaranteeing consistent quality and preventing dust from adhering to the silicon wafer surface at any stage, thereby improving the yield of silicon wafers.

[0045] Accordingly, the docking position 20, the buffer station 30, and the device 40 are equipped with transfer tracks that connect with the trolley 10 and are arranged in the same direction for placing the film baskets; so that the film baskets can be matched and docked with each other along the transfer tracks in the same direction in the docking position 20, the buffer station 30, and the device 40. Of course, transfer tracks in different directions that connect with the trolley 10 can be set inside the buffer station 30, which is a setting of the adjustable space inside the buffer station 30 itself, and is not specifically limited here.

[0046] In order to ensure the cleanliness of the silicon wafers in the connection position 20, buffer station 30 and equipment 40, each of the connection position 20, buffer station 30 and equipment 40 is required to be equipped with an FFU purifier for filtering the air entering its cavity, and also with an exhaust device for exhausting air; in addition, each is equipped with a temperature and humidity tester, a particle size tester and a pressure tester for monitoring the temperature, humidity, cleanliness and air pressure in the cavity.

[0047] Preferably, the particle size analyzer 60 can be a MET ONEHHPC2+, which is a thousand-level air particle counter; the temperature and humidity tester and the pressure tester are conventional testing equipment, which are not specifically limited here and can be purchased on the market.

[0048] In this embodiment, the buffer station 30 can not only buffer wafer baskets containing silicon wafers, but also wafer rods, wafer square rods, or silicon rods awaiting wire cutting. It can also implement multi-module extended buffering, with at least 160 buffer storage locations per layer, and can achieve first-in, first-out (FIFO) product management, ensuring the traceability of all products. Furthermore, the buffer station is a sealed storage transfer station, with its internal configuration matching the standard configuration of the trolley 10, and can freely communicate with the MES (Manufacturing Execution System).

[0049] The transfer method designed in this invention can ensure that silicon wafers are transported under a slightly positive pressure and in a Class 1000 clean environment throughout the entire handling process, preventing dust contamination of the silicon wafer surface, improving the surface quality of the silicon wafers, and increasing the yield of silicon wafers by 0.5-0.8%.

[0050] The embodiments of the present invention have been described in detail above. These descriptions are merely preferred embodiments and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A method for transporting silicon wafers while maintaining their cleanliness, characterized in that the steps include... include: The wafer basket containing the silicon wafers is transported to the transport trolley; The output from the trolley is sent to the buffer station; Output from the trolley to the device; The trolley, the buffer station, and the equipment are all provided with a cavity for carrying the silicon wafer, and the cavity is provided with an FFU purifier and an exhaust device. The FFU purifier is used to filter the air entering the cavity, and the exhaust device is used to exhaust air. When the trolley docks with the buffer station and the equipment, it forms a sealed cavity, which is sealed by an automatic rolling shutter door. When the cleanliness, temperature, humidity, and air pressure of the cavity and the passage cavity in the trolley, the buffer station, and the equipment are all the same and all meet the preset standards, the tray is controlled to pass through the passage cavity. The cache station includes several cache layers, each cache layer is provided with several cache storage bits with dual-pair interfaces, and the connection point between the cache station and the trolley is provided with a docking position, which can be docked with any cache layer. The cleanliness standard is set at no more than 1,000 particles per cubic meter, and the particle size is no greater than 0.5 μm. The temperature and humidity settings are as follows: temperature 21-26℃, humidity 40-60%; The pressure setting standard is a slightly positive pressure state.

2. The method for transporting silicon wafers according to claim 1, characterized in that, A docking position for docking with the trolley is provided at the connection point between the buffer station and the trolley; Automatic roller shutters are provided in alignment at the connection point, the trolley, and the buffer station. Furthermore, in the connecting position, the trolley, and the buffer station, the tray can enter from the roller shutter door at one end and exit from the roller shutter door at the other end.

3. The method for transporting silicon wafers according to claim 2, characterized in that, The connecting position, the trolley, and the buffer station are all equipped with a transfer track for placing the tray; The transfer tracks in the connecting position, the trolley, and the buffer station are matched and connected to each other.

4. The method for transporting silicon wafers according to claim 3, characterized in that, The connecting position, the trolley, and the buffer station are all equipped with FFU purifiers for filtering the air entering the cavity, and are also equipped with exhaust devices for ventilation.

5. A method for transporting silicon wafers that maintains their cleanliness according to claim 2 or 3, characterized in that, Each of the connecting position, the trolley, and the buffer station is equipped with a testing instrument for monitoring the temperature, humidity, cleanliness, and air pressure of the cavity.

6. The method for transporting silicon wafers according to claim 5, characterized in that, Each cached storage bit has two pairs of interfaces.

7. The method for transporting silicon wafers according to claim 6, characterized in that, The device is also provided with a docking interface for the trolley, and the roller shutter door is also provided on the docking interface.

8. A transfer method for maintaining the cleanliness of silicon wafers according to claim 6 or 7, characterized in that, The device also includes an FFU purifier for purifying air and a testing instrument for monitoring temperature, humidity, cleanliness, and air pressure.

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