Anti-thermal-radiation low-temperature cold trap for evaporation equipment

Abstract

The invention discloses an anti-thermal-radiation low-temperature cold trap for evaporation equipment, which is characterized in that a GM refrigerator is mounted at a mounting opening of a shell, a cold head extending into a containing cavity from the mounting opening is arranged on the GM refrigerator, and a cold plate is mounted on the cold head and faces a working opening; the baffle unit is located at the working opening, an annular air inlet is formed in the working opening, the projection of the cold plate on the baffle unit is located on the baffle unit, and the baffle unit comprises a plurality of radiation baffles which are sequentially arranged in the direction away from the cold plate at intervals. According to the heat-radiation-resistant low-temperature cold trap with the optimized design, the multiple layers of radiation baffles arranged at intervals are arranged in the working window, heat radiation can be effectively isolated in the evaporation process, meanwhile, water molecules analyzed through evaporation can enter the shell to be captured by the cold plate, and therefore cleaner vacuum is created for the vacuum cavity, and the evaporation film forming quality is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of cryogenic cold traps, and particularly to a heat-radiation-resistant cryogenic cold trap for evaporation equipment. Background Art

[0002] Vacuum coating processes are extremely widely used, covering many fields such as semiconductors, display panels, and photovoltaics. The largest component in vacuum coating equipment is the vacuum forming system, which consists of vacuum pumps such as cryogenic cold traps and molecular pumps; according to different reaction principles (emission sources), vacuum coating can be divided into evaporation coating, sputtering coating, ion source coating, etc. Among them, the evaporation source of evaporation coating is a high-temperature device, which will form a certain heat load on the cryogenic cold trap of the vacuum device, greatly affecting the working performance of the cryogenic cold trap.

[0003] A cryogenic cold trap is also known as a water vapor pump because it is mainly used to pump out water vapor. When the vacuum chamber is evacuated, the water adsorbed on the inner wall surface will slowly desorb, and the target of evaporation coating will also slowly release water vapor due to high temperature. When the pressure in the chamber is lower than 10-3 Torr, the water vapor content exceeds 97% in the residual gas load. Therefore, water becomes the main obstacle to the chamber reaching the background pressure, and in the evaporation coating process, water molecules will interfere with the chemical properties of film formation and affect the output. In order to maximize the process production output, it is very important to increase the pumping speed of water vapor.

[0004] CN218474899U proposes a cryogenic cold trap, which extends the cold head of the refrigerator into the shell, improving the refrigeration efficiency of the cold trap compared with the conventional condensation effect through the condensation pipeline; and an outer cover is arranged around the cold head to protect the cold head and reduce the heat load on the cold head. However, the cold trap shell of this patent is cylindrical. On the one hand, it is not conducive to the water vapor molecules rebounding to the condensation plate for condensation. On the other hand, the cylindrical shell makes the internal space utilization rate of the cold trap extremely low; in addition, although a reflector is arranged behind the condensation plate, there is no protection measure on the front, so that the condensation plate faces the customer chamber and bears a large heat load; moreover, this cold trap does not have a regeneration heating device, resulting in low regeneration efficiency.

[0005] CN103223260A proposes a cryogenic cold trap, which is connected in series between the molecular pump and the chamber, and uses two refrigeration mechanisms to construct multiple cooling units to achieve the purpose of continuous operation of the cold trap. This patent's cryogenic cold trap, as an enhanced pump for the molecular pump to pump out water vapor, must be connected in series in front of the molecular pump and cannot be used alone as a vacuum pump for pumping out water vapor; in addition, the cooling units of this cold trap also do not have heat radiation protection measures; the regeneration of this cold trap is carried out by reversing the motor of the refrigerator. This regeneration method is carried out by gradually warming up the cold stage, and the heating efficiency for the cooling unit is not high.

[0006] CN115324868A proposes a water extraction low-temperature pump, which also extends the cold head of the refrigerator into the shell to improve the refrigeration efficiency; in addition, heating blocks are added at the first-stage cold stage and the second-stage cold stage, which improves the regeneration efficiency of the water vapor pump to a certain extent; the inclined design at the bottom of the anti-radiation cold screen of this patented water vapor pump is conducive to the discharge of liquid water during regeneration. In this patent, the baffle and cold screen structures that mainly condense water vapor face the customer cavity and do not take any anti-radiation measures; in addition, the heating blocks installed on the cold stage fail to directly heat the cold screen and baffle, resulting in low efficiency during the regeneration of the water vapor pump. Summary of the Invention

[0007] To solve the technical problems existing in the background art, the present invention proposes an anti-thermal radiation low-temperature cold trap for a vapor deposition device.

[0008] An anti-thermal radiation low-temperature cold trap for a vapor deposition device proposed by the present invention includes: a GM refrigerator, a shell, a cold plate, and a baffle unit;

[0009] The shell has an accommodation cavity inside. Oppositely arranged installation openings and working openings are provided on the side wall of the accommodation cavity. The GM refrigerator is installed at the installation opening. A cold head extending from the installation opening into the accommodation cavity is provided on the GM refrigerator. The cold plate is installed on the cold head and faces the working opening. The baffle unit is located at the working opening. An annular air inlet is formed between the outer edge of the baffle unit and the inner edge of the working opening. The projection of the cold plate on the baffle unit is located on the baffle unit. The baffle unit includes a plurality of radiation baffles arranged at intervals in a direction away from the cold plate.

[0010] Preferably, the shell has an arc-shaped inner wall with an inner diameter gradually increasing from the installation opening to the working opening direction.

[0011] Preferably, the shell and the radiation baffle are made of metal materials, and the inner wall of the shell and the surface of the radiation baffle are treated with mirror finish.

[0012] Preferably, the cold plate is made of oxygen-free copper material and its surface is treated with bright nickel plating.

[0013] Preferably, support columns are provided on the baffle unit and are connected to the inner wall of the shell through the support columns.

[0014] Preferably, a plurality of support columns are provided on the baffle unit. The plurality of support columns are arranged around the cold plate. One end of the support column is connected to the shell and the other end sequentially connects a plurality of radiation baffles.

[0015] Preferably, the diameter of the support column gradually decreases in the direction close to the baffle unit.

[0016] Preferably, an annular heat insulation gasket is provided between adjacent two radiation baffles, and the annular heat insulation gasket is sleeved on the support column.

[0017] Preferably, a heating wire is further provided on one side of the cold plate close to the baffle unit.

[0018] Preferably, lifting lugs and drain ports are respectively provided at opposite ends of the housing.

[0019] In the present invention, for the anti-thermal radiation low-temperature cold trap for a vapor deposition apparatus, the GM refrigerator is installed at the installation opening of the housing. The GM refrigerator is provided with a cold head extending from the installation opening into the accommodation cavity. The cold plate is installed on the cold head and is arranged facing the working opening. The baffle unit is located at the working opening to form an annular air inlet at the working opening. The projection of the cold plate on the baffle unit is located on the baffle unit. The baffle unit includes a plurality of radiation baffles arranged at intervals in a direction away from the cold plate. Through the above optimized design of the anti-thermal radiation low-temperature cold trap, multiple layers of spaced radiation baffles are arranged at the working window, which can effectively isolate thermal radiation during the vapor deposition process. At the same time, the water molecules analyzed and deposited can enter the housing and be captured by the cold plate, thereby creating a cleaner vacuum for the vacuum chamber and further improving the quality of the vapor deposition film. Description of the Drawings

[0020] Figure 1 It is a schematic structural diagram of an embodiment of an anti-thermal radiation low-temperature cold trap for a vapor deposition apparatus proposed by the present invention.

[0021] Figure 2 It is a schematic diagram of the working state of an embodiment of an anti-thermal radiation low-temperature cold trap for a vapor deposition apparatus proposed by the present invention.

[0022] Figure 3 It is a schematic internal structure diagram of an embodiment of an anti-thermal radiation low-temperature cold trap for a vapor deposition apparatus proposed by the present invention.

[0023] Figure 4 It is a partial schematic diagram of the baffle unit of an embodiment of an anti-thermal radiation low-temperature cold trap for a vapor deposition apparatus proposed by the present invention.

[0024] Figure 5 It is a schematic diagram of the cold plate structure of an embodiment of an anti-thermal radiation low-temperature cold trap for a vapor deposition apparatus proposed by the present invention. Detailed Embodiments

[0025] As Figures 1 to 5 shown, Figure 1 It is a schematic structural diagram of an embodiment of an anti-thermal radiation low-temperature cold trap for a vapor deposition apparatus proposed by the present invention, Figure 1 It is a schematic structural diagram of an embodiment of an anti-thermal radiation low-temperature cold trap for a vapor deposition apparatus proposed by the present invention, Figure 2Schematic diagram of the working state of an embodiment of a heat - radiation - resistant low - temperature cold trap for an evaporation coating device proposed by the present invention Figure 3 Schematic diagram of the internal structure of an embodiment of a heat - radiation - resistant low - temperature cold trap for an evaporation coating device proposed by the present invention Figure 4 Partial schematic diagram of a baffle unit of an embodiment of a heat - radiation - resistant low - temperature cold trap for an evaporation coating device proposed by the present invention Figure 5 Schematic diagram of the cold plate structure of an embodiment of a heat - radiation - resistant low - temperature cold trap for an evaporation coating device proposed by the present invention

[0026] Refer to Figure 1 and 2 A heat - radiation - resistant low - temperature cold trap for an evaporation coating device proposed by the present invention includes: a GM refrigerator 1, a housing 2, a cold plate 3, and a baffle unit;

[0027] The housing 2 has an accommodation cavity inside. Oppositely - arranged installation openings and working openings are provided on the side wall of the accommodation cavity. The GM refrigerator 1 is installed at the installation opening. A cold head 11 extending from the installation opening into the accommodation cavity is provided on the GM refrigerator 1. The cold plate 3 is installed on the cold head 11 and is arranged facing the working opening. The baffle unit is located at the working opening. An annular air inlet is formed between the outer edge of the baffle unit and the inner edge of the working opening. The projection of the cold plate 3 on the baffle unit is located on the baffle unit. The baffle unit includes a plurality of radiation baffles 4 arranged at intervals in sequence in a direction away from the cold plate 3.

[0028] Refer to Figure 1 and 3 During the specific working process of the heat - radiation - resistant low - temperature cold trap for an evaporation coating device in this embodiment, the working opening of the low - temperature cold trap is connected to the vacuum chamber of the evaporation coating device. When the vacuum chamber reaches a cold - trap opening pressure below 10 Pa, the cold trap can be opened to evacuate water vapor. When starting the evaporation coating process, there is no need to turn off the cold trap. The multi - layer radiation baffles of the cold trap can effectively isolate heat radiation. The multi - layer baffles and air layers are arranged at intervals, ensuring the heat - insulation effect on the cold head and cold plate inside the housing. At the same time, the water molecules desorbed during evaporation can also bounce off the inner wall of the housing onto the cold plate and be captured, creating a cleaner vacuum for the vacuum chamber and improving the chemical properties of the film formation.

[0029] In this embodiment, the proposed anti-thermal radiation low-temperature cold trap for an evaporation device has a GM refrigerator installed at the installation opening of the housing. The GM refrigerator is provided with a cold head extending from the installation opening into the accommodation cavity. A cold plate is installed on the cold head and is arranged facing the working opening. A baffle unit is located at the working opening to form an annular air inlet at the working opening. The projection of the cold plate on the baffle unit is located on the baffle unit. The baffle unit includes a plurality of radiation baffles arranged at intervals in a direction away from the cold plate. Through the above optimized anti-thermal radiation low-temperature cold trap, multiple layers of spaced radiation baffles are arranged at the working window, which can effectively isolate thermal radiation during the evaporation process. At the same time, the water molecules analyzed by evaporation can enter the housing and be captured by the cold plate, thereby creating a cleaner vacuum for the vacuum chamber and further improving the evaporation film formation quality.

[0030] In a specific embodiment of the housing, the housing 2 has an arc-shaped inner wall with an inner diameter gradually increasing from the installation opening to the working opening direction. During the evaporation process, the water vapor molecules entering the housing through the annular air inlet hit the housing and are effectively rebounded onto the cold plate for condensation, improving the water vapor capture efficiency. Specifically, in the material selection, the housing 2 and the radiation baffle 4 are made of metal materials, and the inner wall of the housing 2 and the surface of the radiation baffle 4 are mirror-treated to further improve the rebounding effect.

[0031] During actual use, to facilitate the installation of the cold trap, an installation flange structure can be provided on the outer periphery of the working opening.

[0032] In the material selection of the cold plate, the cold plate 3 is made of oxygen-free copper material and its surface is treated with bright nickel plating. Similarly, the cold head can also be treated with bright nickel plating on its surface, which can effectively reflect the thermal radiation from the housing to it.

[0033] To balance the capture ability of the cold trap and the heat insulation effect of the baffle, in the specific design, the baffle unit includes four to six radiation baffles.

[0034] Refer to Figure 1 , in the specific installation method of the baffle unit, the baffle unit is provided with support columns 6 and is connected to the inner wall of the housing 2 through the support columns 6. Specifically, the baffle unit is provided with a plurality of support columns 6, and the plurality of support columns 6 are arranged around the cold plate 3. One end of the support column 6 is connected to the housing 2 and the other end is sequentially connected to a plurality of radiation baffles 4.

[0035] In a further specific design method, the diameter of the support column 6 gradually decreases in a direction close to the baffle unit. The diameter is reduced at the connection position between the support column and the baffle, effectively increasing the contact thermal resistance and reducing the heat conduction from the housing to the heat insulation baffle.

[0036] Furthermore, refer to Figure 4 , an annular heat insulation gasket 5 is provided between two adjacent radiation baffles 4. The annular heat insulation gasket 5 is sleeved on the support column 6, effectively avoiding thermal contact between adjacent baffles.

[0037] In addition, referring to Figure 5 , in other specific embodiments, in order to improve the regeneration efficiency of the cold trap, a heating wire 7 is also provided on the side of the cold plate 3 close to the baffle unit. After the evaporation coating process is completed, the cold trap can be regenerated by turning off the refrigerator and turning on the heating wire, so that the water vapor condensed on the cold plate and the cold head is converted into liquid water, effectively accelerating the exhaust efficiency of the cold plate during the regeneration of the cold trap. In order to facilitate the discharge of the liquid water, a drain port 8 can be provided on the housing. Specifically, lifting lugs 10 and a drain port 8 are respectively provided at opposite ends of the housing 2. The heating wire adopts a vortex structure and is evenly distributed on the cold plate.

[0038] The low-temperature cold trap of the present invention will be described in detail below through specific examples. The low-temperature cold trap proposed in this embodiment is applied to vacuum evaporation coating in the photovoltaic industry. The specific structure of the anti-thermal radiation low-temperature cold trap includes a GM refrigerator 1, a housing 2, a cold plate 3, a radiation baffle 4, a gasket 5, a support column 6, a heating wire 7, a drain port 8, a signal interface 9, and lifting lugs 10.

[0039] For the convenience of description and to more intuitively understand the position state of the cold trap structure, the "front" and "back" in the following text are consistent with the front and back positions in Figure 1 , the front and back directions of the cold trap are consistent with the gas movement direction. In addition, this orientation expression has nothing to do with the installation position of the cold trap in the vacuum chamber.

[0040] In this embodiment, the GM refrigerator 1 is a single-stage refrigerator, which provides a cold source for the cold plate, and the temperature range can be controlled between 90 and 130K; because it mainly condenses water vapor, there is no need to use a two-stage refrigerator, reducing the cost. Secondly, in this embodiment, the cold stage of the refrigerator is treated with bright nickel plating to reduce the infrared emissivity and reduce the thermal radiation of the housing 2 to it.

[0041] The housing 2 is made of 304 stainless steel, which is used to separate the internal and external vacuum containers of the cold trap. The front of the cold trap is connected to the customer cavity, and the GM refrigerator 1 is installed at the back. The arc design of the housing reduces the space occupied by the cold trap on the one hand, and on the other hand, the arc design is conducive to the water molecules being rebounded onto the cold plate 3 for condensation after hitting the housing.

[0042] The cold plate 3 is made of oxygen-free copper, with a bright nickel plating on the surface. It is thermally connected to the cold stage of the GM refrigerator through bolts and is used to condense the water molecules in the cavity. The bright nickel plating treatment can reduce the thermal radiation of the housing 2 and the radiation baffle 4 to it.

[0043] The radiation baffle 4 is made of 304 stainless steel, with a mirror finish on the surface, and there are 5 layers in total. The diameter exceeds that of the cold plate, mainly used to isolate the thermal radiation of the high-temperature heat source in the customer cavity during evaporation coating from the cold plate 3.

[0044] The gasket 5 is made of polytetrafluoroethylene, with low outgassing rate and low thermal conductivity properties, and is mainly used to space the five-layer radiation baffle 4 to avoid direct thermal contact between the radiation baffles 4.

[0045] The support rods 6 are made of 304 stainless steel, with a total of 4, and are evenly welded inside the housing 2 to support the radiation baffle 4. The root diameter is larger for welding and fixing; the upper diameter is reduced to increase the contact thermal resistance and reduce the heat conduction of the housing.

[0046] The heating wire 7 is in a vortex shape and is fixed to the cold plate 3 by rivets, and one end is electrically connected to the signal interface 9. When the cold trap is regenerated, the heating wire 7 heats the cold plate 3 for exhaust. This kind of heating wire directly fixed on the cold plate has higher heating efficiency and more uniform heating for the cold plate 3.

[0047] The drain port 8 is arranged directly below the cold trap and is externally connected to a manual baffle valve. After the regeneration of such a separate cold trap not connected to the molecular pump, liquid water often forms. The liquid water will finally converge to the drain port 8 along the housing. After the regeneration is completed, the baffle valve can be opened to drain the liquid water, and there is no need to remove the cold trap for wiping. In addition, the drained drain port 8 can also be used as the evacuation port of the cold trap.

[0048] The signal interface 9 is arranged on the GM refrigerator and is a 10-pin socket interface for outputting the cold trap temperature signal and inputting the heating signal. Some of the 10-pin socket interfaces are used to connect the temperature sensor, and some are used to connect the heating wire 9.

[0049] The lifting lug 10 is arranged directly above the cold trap, which is convenient for hoisting during the installation of the cold trap and saves manpower.

[0050] During operation, the front of the cryogenic cold trap is connected to the vacuum chamber of the evaporation equipment. When the vacuum chamber reaches a pressure below 10 Pa, the cold trap can be opened to evacuate water vapor. When starting the evaporation process, there is no need to turn off the cold trap. The radiation baffle of the cold trap can well isolate thermal radiation, and the water molecules desorbed during evaporation can also bounce back to the cold plate through the housing and be captured, creating a cleaner vacuum for the vacuum chamber and improving the chemical properties of the film formation. After the evaporation process is completed, the cold trap can be regenerated (turn off the refrigerator and turn on the heating wire). When the temperature reaches 50 °C, the regeneration process ends. When the vacuum chamber returns to atmospheric pressure, the baffle valve of the drain port can be opened to drain the liquid water. After simply wiping the drain port, the baffle valve can be closed to perform the coating of the next product.

[0051] The above is only the preferred specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitution or change, and should be covered by the protection scope of the present invention.

Claims

1. A low temperature cold trap for evaporation equipment with heat radiation resistance, characterized in that: include: GM refrigerator (1), housing (2), cold plate (3) and baffle unit; The shell (2) has a housing cavity inside, and the side wall of the housing cavity is provided with a mounting opening and a working opening which are arranged opposite to each other. The GM refrigerator (1) is mounted at the mounting opening, and the GM refrigerator (1) is provided with a cold head (11) extending from the mounting opening into the housing cavity. The cold plate (3) is mounted on the cold head (11) and arranged toward the working opening. The baffle unit is located at the working opening, and an annular air inlet is formed between the outer edge of the baffle unit and the inner edge of the working opening. The projection of the cold plate (3) on the baffle unit is located on the baffle unit, and the baffle unit includes a plurality of radiation baffles (4) arranged in sequence and spaced apart in a direction away from the cold plate (3).

2. The heat radiation resistant low temperature cold trap for evaporation equipment according to claim 1, characterized in that: The housing (2) has an arc-shaped inner wall whose inner diameter gradually increases from the installation opening toward the working opening.

3. The heat radiation resistant low temperature cold trap for evaporation equipment according to claim 1 or 2, characterized in that: The shell (2) and the radiation baffle (4) are made of metal material, and the inner wall of the shell (2) and the surface of the radiation baffle (4) are mirror-finished.

4. The heat radiation resistant low temperature cold trap for evaporation equipment according to claim 1 or 2, characterized in that: The cold plate (3) is made of oxygen-free copper material and its surface is plated with bright nickel.

5. The heat radiation resistant low temperature cold trap for evaporation equipment according to claim 1, characterized in that: A support column (6) is provided on the baffle unit and is connected to the inner wall of the shell (2) via the support column (6).

6. The heat radiation resistant low temperature cold trap for evaporation equipment according to claim 5, characterized in that: A plurality of support columns (6) are provided on the baffle unit, and the plurality of support columns (6) are arranged around the cold plate (3), one end of the support column (6) is connected to the shell (2) and the other end is connected in sequence to the plurality of radiation baffles (4).

7. The heat radiation resistant low temperature cold trap for evaporation equipment according to claim 5, characterized in that: The diameter of the support column (6) gradually decreases towards the baffle unit.

8. The heat radiation resistant low temperature cold trap for evaporation equipment according to claim 5, characterized in that: An annular heat-insulating gasket (5) is provided between two adjacent radiation baffles (4), and the annular heat-insulating gasket (5) is sleeved on the supporting column (6).

9. The heat radiation resistant low temperature cold trap for evaporation equipment according to claim 1, characterized in that: A heating wire (7) is also provided on one side of the cold plate (3) close to the baffle unit.

10. The heat radiation resistant low temperature cold trap for evaporation equipment according to claim 1, characterized in that: The shell (2) is provided with lifting ears (10) and drainage ports (8) at opposite ends.

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