A cryogenic pump for uniform adsorption of low temperature surfaces

Abstract

The present invention belongs to the technical field of cryopumps, and specifically relates to a cryopump with uniform adsorption of cryogenic surfaces. It comprises a pump body, a refrigerator and a cryogenic array, wherein the pump body has a main air inlet, a front-stage radiation shielding cylinder is arranged around the main air inlet, the cold head of the refrigerator is arranged in the pump body, and the cryogenic array is arranged on the cold head. The cryogenic array is composed of a cryogenic surface box and a cryogenic surface group, and the cryogenic surface group is composed of a number of cryogenic panels fixed on the cold head at a set distance; a rear-stage radiation shielding cylinder is also arranged in the pump body, and the diameter of the rear-stage radiation shielding cylinder is larger than that of the front-stage radiation shielding cylinder, and the ends of the two are staggered to form a secondary air inlet in the pump body, and the secondary air inlet is connected to the gas guide inclined plate and arranged toward the cryogenic surface box. The cryogenic pump provided by the present invention can prevent a large number of sucked gas molecules from being adsorbed on the top cryogenic panel, resulting in excessive saturation of the top cryogenic panel, and a significant decrease in the pumping speed.

Description

Technical Field

[0001] The invention belongs to the technical field of cryopumps, and in particular relates to a cryopump with uniform adsorption on a low-temperature surface. Background Art

[0002] Cryopumps are vacuum pumps with low ultimate pressure and high pumping rate for obtaining clean vacuum. They are widely used in the research and production of semiconductors and integrated circuits, as well as molecular beam research, vacuum coating equipment, vacuum surface analysis instruments, ion implanters and space simulation devices.

[0003] In the prior art, it is difficult to uniformly adsorb the gas between the cryogenic surfaces of each stage of the cryogenic pump, especially a large amount of working gas will be adsorbed by the top cryogenic surface closest to the radiation shield, resulting in a significant decrease in the cryogenic pump pumping speed once the adsorption amount of the top cryogenic surface is close to saturation; at the same time, the gas entering from the gap between the front-stage radiation shielding wall and the rear-stage radiation shielding wall has the characteristics of small gas volume, coupled with the effect of the gas guide baffle and the gas guide inclined plate, the gas flow direction is directional, the prior art often uses a multi-stage disc structure of the cryogenic surface, which will lead to low gas adsorption efficiency per unit area, the excessively large cryogenic surface area will cause a large refrigeration burden on the refrigerator, and it is easy to cause the cryogenic pump efficiency to decrease or safety hazards. Therefore, there is still a lot of room for improvement in the prior art cryogenic pump. Summary of the invention

[0004] The object of the present invention is to provide a cryopump with uniform adsorption on a low temperature surface, aiming to solve the technical problems raised in the above-mentioned background technology.

[0005] The present invention adopts the following technical solution.

[0006] A cryogenic pump with uniform adsorption of cryogenic surfaces, comprising a pump body, a refrigerator connected to the pump body, and a cryogenic array arranged inside the pump body, wherein the pump body has a main air inlet, a front-stage radiation shielding cylinder is arranged around the main air inlet, a cold head and a cold cylinder of the refrigerator are arranged inside the pump body and extend into the front-stage radiation shielding cylinder, the cryogenic array is arranged on the cold head, comprising a cryogenic surface box arranged toward the cold cylinder and covered on the outside of the cold cylinder, and a cryogenic surface group connected to the cold head, the cryogenic surface group is composed of a plurality of cryogenic panels fixed on the cold head at a set distance; the cold cylinder is also connected to a rear-stage radiation shielding cylinder arranged toward the main air inlet, the diameter of the rear-stage radiation shielding cylinder is greater than the diameter of the front-stage radiation shielding cylinder, the ends of the rear-stage radiation shielding cylinder and the front-stage radiation shielding cylinder are staggered to form a secondary air inlet in the pump body, the secondary air inlet is connected to a gas guide inclined plate, and the air outlet of the gas guide inclined plate is arranged toward the cryogenic surface box.

[0007] Preferably, the refrigerator includes a primary cold cylinder, a primary cold head, a secondary cold cylinder and a secondary cold head which are sequentially connected to the compressor; the low-temperature array is arranged on the secondary cold head, including a low-temperature surface box arranged toward the secondary cold cylinder and covering the outside of the secondary cold cylinder and a low-temperature surface group connected to the secondary cold head; the rear-stage radiation protection shielding cylinder is arranged between the primary cold head and the secondary cold cylinder, so that the low-temperature array is in the space formed by the front-stage radiation protection shielding cylinder and the rear-stage radiation protection shielding cylinder.

[0008] Preferably, the low-temperature noodle box is a rectangular box, the low-temperature noodle box is open on one side facing the secondary cooling cylinder, and a plurality of ventilation holes are arranged on the box body of the low-temperature noodle box.

[0009] Preferably, each of the low-temperature panels comprises a circular plate and a circular ring coaxially arranged with the circular plate, an annular gap is provided between the concentric circular ring and the circular plate, and connectors are arranged at set intervals in the annular gap for connecting the concentric circular ring and the circular plate.

[0010] Preferably, the outermost circular ring of the low-temperature panel has its ring surface inclined downward.

[0011] Preferably, the inner and outer surfaces of the low-temperature noodle box and the low-temperature panel are both provided with an adsorption layer, and the material of the adsorption layer is activated carbon, molecular sieve or porous ceramic.

[0012] Preferably, a radiation-proof baffle is provided on the main air inlet, and the radiation-proof baffle is a multi-layer corrugated circular plate with an annular gap, the outer plate surface of each layer of the corrugated circular plate is inclined downward, and the corrugated circular plates are fixedly connected by brackets.

[0013] Preferably, a connecting piece is provided at the intersection of the ends of the rear-stage radiation protection shielding tube and the front-stage radiation protection shielding tube to fix the gap formed between the tube walls of the rear-stage radiation protection shielding tube and the front-stage radiation protection shielding tube, and the ends of the rear-stage radiation protection shielding tube and the front-stage radiation protection shielding tube are respectively connected to the gas guide inclined plates to form an air outlet channel of the secondary air inlet.

[0014] Preferably, the rear-stage radiation protection shielding tube and the front-stage radiation protection shielding tube are both made of insulating materials.

[0015] Preferably, a guide baffle is further provided in the rear-stage radiation shielding tube, and the guide baffle is arranged on the air outlet path of the secondary air inlet, one end of the guide baffle is fixed to the inner tube wall of the rear-stage radiation shielding tube, and the other end extends toward the low-temperature array.

[0016] Preferably, the guide baffle is electrically connected to a motor, and the motor controls the inclination angle of the guide baffle, thereby guiding the outlet air of the secondary air inlet to flow toward the low-temperature surface box and / or the low-temperature array.

[0017] The beneficial effects of the present invention are:

[0018] 1. The cryopump of the present invention is provided with front and rear two-stage radiation shielding walls, wherein a gap is provided between the wall of the front-stage shielding tube and the wall of the rear-stage shielding tube and a gas guide plate is provided, which can effectively direct part of the gas entering the pump body into the cryogenic surface box. The cryogenic surface box, as the second-stage cryogenic surface after the cryogenic array, can prevent all gases from entering the pump body only through the radiation shielding baffle, causing the cryogenic array to reach saturation prematurely, while the adsorption saturation of the remaining cryogenic surfaces is smaller than that of the cryogenic surface group close to the main air inlet.

[0019] 2. In the structural design of the cryogenic panel, multiple layers of circular rings are added. The hollowed-out gas guide area between the circular rings and the discs can ensure that when the gas molecules pass through the radiation protection baffle area and collide with the top cryogenic surface, part of the gas will directly penetrate from the gas guide area to the lower cryogenic surface, and then penetrate step by step to the bottom cryogenic surface, which effectively reduces the load pressure of the gas adsorption amount on the top cryogenic surface, improves the problem of uneven adsorption amount on each level of cryogenic surface, and avoids the phenomenon of a significant decrease in the pumping speed of the cryogenic pump in a short time.

[0020] 3. By opening holes on the surface of the low-temperature surface box, it helps to increase the probability of airflow contacting the walls on both sides of the low-temperature surface box and improve the cold conduction efficiency.

[0021] 4. By setting the second-stage low-temperature surface as a rectangular cylindrical structure and installing it at the middle and bottom end of the secondary cold head, the gas entering from the secondary air inlet directly collides with the surrounding walls of the cylinder and is adsorbed. Since the area of ​​the rectangular cylindrical low-temperature surface is much smaller than that of the disc-structured low-temperature surface occupying the same area, it can effectively reduce the burden on the refrigerator. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention.

[0023] Figure 1 This is a schematic structural diagram of the cryopump provided by the present invention.

[0024] Figure 2 This is a schematic diagram of the structure of the refrigerator in the cryopump.

[0025] Figure 3 It is a schematic diagram of the structure of the low-temperature surface group in the cryopump.

[0026] Figure 4 This is a schematic diagram of the structure of the cryogenic surface box in the cryogenic pump.

[0027] Figure 5This is a schematic diagram of the structure of the connection between the front-stage radiation shielding tube and the rear-stage radiation shielding tube in the cryogenic pump.

[0028] Figure 6 Schematic diagram of the structure of the radiation shield in the cryogenic pump.

[0029] exist Figure 1-Figure 6 middle:

[0030] 10- Pump housing 11- Main air inlet 12- Secondary air inlet

[0031] 20-refrigeration machine 21-first-stage cooling cylinder 22-first-stage cooling head 23-second-stage cooling cylinder 24-second-stage cooling head 25-compressor

[0032] 30- low temperature surface group 31- low temperature panel 311- circular plate 312- circular ring 313- connecting piece

[0033] 40- low temperature noodle box 41- vent

[0034] 51-front stage radiation shielding tube 52-rear stage radiation shielding tube

[0035] 60-Gas guide ramp

[0036] 70- radiation shield 71- corrugated circular plate 72- bracket

[0037] 80-Deflector baffle DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the following is a diagram of the present invention. Figure 1-Figure 6 It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] It should be noted that the directions or positional relationships indicated by terms such as “center”, “up”, “down”, “left”, “right”, “vertical”, “horizontal”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on the present invention.

[0040] Example 1

[0041] A cryopump with uniform adsorption of low-temperature surfaces comprises a pump body with a pump casing 10, a refrigerator 20 connected to the pump body, and a cryogenic array arranged inside the pump body.

[0042] The refrigerator 20 includes a compressor 25 providing a helium cold source, and a primary cold cylinder 21, a primary cold head 22, a secondary cold cylinder 23 and a secondary cold head 24 connected to the compressor 25 in sequence, wherein the primary cold cylinder 21 is used to connect the compressor 25 and the primary cold head 22, and the secondary cylinder body 23 is used to connect the primary cold head 22 and the secondary cold head 24.

[0043] The pump housing 10 has a main air inlet 11 , on which a radiation-proof baffle 70 is arranged. The radiation-proof baffle 70 is a multi-layer corrugated circular plate 61 with an annular gap. The outer plate surface of each layer of the corrugated circular plate 61 is inclined downward, and the corrugated circular plates 61 are fixedly connected by brackets 62 .

[0044] A front-stage radiation shielding cylinder 51 is arranged around the main air inlet 11 , and a secondary cold cylinder 23 and a secondary cold head 24 of the refrigerator 20 are arranged inside the pump body and extend into the front-stage radiation shielding cylinder 51 .

[0045] The low-temperature array is arranged on the secondary cold head 24, including a low-temperature surface box 40 arranged toward the secondary cold cylinder 23 and covering the outside of the secondary cold cylinder 23, and a low-temperature surface group 30 connected to the secondary cold head 24. The low-temperature surface group 30 is composed of a plurality of low-temperature panels 31 fixed on the cold head at a set distance.

[0046] Each cryogenic panel 31 includes a circular plate 311 and a circular ring 312 coaxially arranged with the circular plate 311, an annular gap is provided between the concentric circular ring 312 and the circular plate 311, and a connecting piece 313 is arranged at a set distance in the annular gap for connecting the concentric circular ring 312 and the circular plate 311, and the outermost circular ring 312 of the cryogenic panel 31 has its annular surface tilted downward. The cryogenic noodle box 40 is a rectangular box body, and the cryogenic noodle box 40 is openly arranged on one side facing the secondary cold cylinder 23, and a plurality of vents 41 are arranged on the box body of the cryogenic noodle box 40.

[0047] In the present invention, the working process of the above-mentioned low-temperature surface group is:

[0048] The adsorption effect of the cryopump on the gas will cause the gas molecules in the vacuum chamber to move in a directional manner toward the exhaust port of the cryopump. The gas enters the internal space of the pump body through the radiation protection baffle 70. First, a large number of gas molecules are incident on the top cryogenic panel 31 of the cryogenic surface group 30, most of which are adsorbed on the surface of the cryogenic panel 31 to form gas frost. Part of the other gas is desorbed from the cryogenic panel 31, and part is reflected to other spaces in the pump body. The rest flows from the annular gap of the top cryogenic panel 31 to the lower cryogenic panel 31. Since each cryogenic panel 31 is provided with a gap structure, the gas molecules gradually flow in from top to bottom through the gap, thereby avoiding that too many gas molecules are adsorbed on the top cryogenic panel 31, resulting in too fast saturation of the top cryogenic panel 31 and a significant decrease in the pumping speed.

[0049] Adsorption layers are also provided on the inner and outer surfaces of the low-temperature surface box 40 and the low-temperature panel 31 . The material of the adsorption layers is activated carbon, molecular sieve or porous ceramic.

[0050] The pump housing 10 also has a rear-stage radiation shielding tube 52 disposed toward the main air inlet 11. The rear-stage radiation shielding tube 52 and the front-stage radiation shielding tube 51 are both made of insulating materials. The rear-stage radiation shielding tube 52 is disposed between the first-stage cold head 22 and the second-stage cold cylinder 23, so that the low-temperature array is in the space formed by the front-stage radiation shielding tube 51 and the rear-stage radiation shielding tube 52.

[0051] Furthermore, the diameter of the rear-stage radiation shielding tube 52 is 2-3 cm larger than the diameter of the front-stage radiation shielding tube 51, so that the intersection of the ends of the rear-stage radiation shielding tube 52 and the front-stage radiation shielding tube 51 can form a secondary air inlet 12 in the pump body.

[0052] Some of the gas molecules inside the pump body enter the middle and rear end of the pump body from the secondary air inlet 12 and are adsorbed by the wall of the low-temperature surface box 40. The surface of the low-temperature surface box 40 is also provided with air vents 41, which can be arranged evenly and at equal intervals. This can increase the contact probability between the gas molecules and the inner surface of the low-temperature surface box 40, and avoid the problem of reduced exhaust efficiency due to a large difference in gas adsorption amount on the inner and outer surfaces.

[0053] In the present invention, a connecting piece 313 is also provided at the intersection of the ends of the rear-stage radiation protection shielding tube 52 and the front-stage radiation protection shielding tube 51 to fix the gap formed between the tube walls of the rear-stage radiation protection shielding tube 52 and the front-stage radiation protection shielding tube 51, and the ends of the rear-stage radiation protection shielding tube 52 and the front-stage radiation protection shielding tube 51 are respectively connected to the gas guide inclined plate 60, and the air outlet of the gas guide inclined plate 60 is arranged toward the low-temperature array to form an air outlet channel of the secondary air inlet 12.

[0054] The setting of the secondary air inlet 12 can guide part of the air entering the pump body to directly contact the low-temperature surface box 40, avoiding the oversaturation of the low-temperature surface group 30 and reducing the adsorption amount, thereby reducing the load pressure of the top low-temperature panel and improving the problem of uneven adsorption of the low-temperature panel.

[0055] Example 2

[0056] During operation of the cryopump, gas molecules enter the pump body from the vacuum chamber through the gaps in the radiation-proof baffle 70 . In order to deflect the pumped gas away from the structural components of the refrigerator, a guide baffle 80 is further provided in the rear-stage radiation-proof shielding tube 52 .

[0057] The guide baffle 80 is arranged on the air outlet path of the secondary air inlet 12 , one end of the guide baffle 80 is fixed to the inner cylinder wall of the rear stage radiation shielding cylinder 52 , and the other end extends toward the low temperature array, thereby guiding the air outlet direction of the secondary air inlet 12 .

[0058] Furthermore, the guide baffle 80 is also electrically connected to the motor, and the inclination angle of the guide baffle 80 is controlled by the motor to keep the evacuated gas away from the structural components of the refrigerator as much as possible, while reducing the movement space of the gas molecules in the low-temperature surface area cooled by liquid helium. The evacuated gas flows toward the low-temperature surface box 40 and / or the low-temperature surface group 30, increasing the probability of collision with the low-temperature surface.

[0059] The above solutions are only an illustration of a preferred example, but are not limited thereto. When implementing the present invention, appropriate replacement and / or modification can be performed according to user needs.

[0060] The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be obvious to those skilled in the art.

[0061] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily realized. Therefore, without departing from the general concept defined by the claims and equivalent scope, the present invention is not limited to the specific details and the illustrations shown and described here.

Claims

1. A cryopump for uniform adsorption of low-temperature surfaces, comprising a pump body with a pump housing (10), a refrigerator (20) connected to the pump body, and a cryogenic array arranged inside the pump body, wherein the pump housing (10) has a main air inlet (11), characterized in that: A front-stage radiation shielding cylinder (51) is arranged around the main air inlet (11); a cold head and a cold cylinder of the refrigerator (20) are arranged inside the pump body and extend into the front-stage radiation shielding cylinder (51); the low-temperature array is arranged on the cold head and includes a low-temperature surface box (40) arranged toward the cold cylinder and covering the outside of the cold cylinder and a low-temperature surface group (30) connected to the cold head; the low-temperature surface group (30) is composed of a plurality of low-temperature panels (31) fixed on the cold head at set intervals; The cold cylinder is also connected to a rear-stage radiation shielding cylinder (52) arranged toward the main air inlet (11); the diameter of the rear-stage radiation shielding cylinder (52) is greater than the diameter of the front-stage radiation shielding cylinder (51); the ends of the rear-stage radiation shielding cylinder (52) and the front-stage radiation shielding cylinder (51) are staggered to form a secondary air inlet (12) in the pump body; the secondary air inlet (12) is connected to a gas guide inclined plate (60); and the air outlet of the gas guide inclined plate (60) is arranged toward the low-temperature array; The refrigerator (20) comprises a primary cold cylinder (21), a primary cold head (22), a secondary cold cylinder (23) and a secondary cold head (24) connected to a compressor in sequence; the low-temperature array is arranged on the secondary cold head (24), and comprises a low-temperature surface box (40) arranged toward the secondary cold cylinder (23) and covering the outside of the secondary cold cylinder (23) and a low-temperature surface group (30) connected to the secondary cold head (24); the rear-stage radiation protection shielding cylinder (52) is arranged between the primary cold head (22) and the secondary cold cylinder (23), so that the low-temperature array is located in a space formed by the front-stage radiation protection shielding cylinder (51) and the rear-stage radiation protection shielding cylinder (52); Each of the low-temperature panels (31) comprises a circular plate (311) and a circular ring (312) coaxially arranged with the circular plate (311), an annular gap being provided between the circular ring (312) and the circular plate (311), and connecting pieces (313) are arranged at a set distance in the annular gap for connecting the circular ring (312) and the circular plate (311).

2. A cryopump for low-temperature surface uniform adsorption according to claim 1, characterized in that: The low-temperature noodle box (40) is a rectangular box body, the low-temperature noodle box (40) is openly arranged on one side facing the secondary cooling cylinder (23), and a plurality of ventilation holes (41) are arranged on the box body of the low-temperature noodle box (40).

3. A cryopump for low-temperature surface uniform adsorption according to claim 1, characterized in that: The outermost circular ring (312) of the low-temperature panel (31) has a ring surface that is inclined downward.

4. A cryopump for low-temperature surface uniform adsorption according to any one of claims 1 to 3, characterized in that: The inner and outer surfaces of the low-temperature noodle box (40) and the low-temperature panel (31) are both provided with an adsorption layer, and the material of the adsorption layer is activated carbon, molecular sieve or porous ceramic.

5. A cryopump for low-temperature surface uniform adsorption according to claim 1, characterized in that: A radiation protection baffle (70) is arranged on the main air inlet (11), and the radiation protection baffle (70) is a multi-layer corrugated circular plate (61) with an annular gap, the outer plate surface of each layer of the corrugated circular plate (61) is arranged to be inclined downward, and the corrugated circular plates (61) are fixedly connected by brackets (62).

6. A cryopump for low-temperature surface uniform adsorption according to claim 1, characterized in that: A connecting piece (313) is provided at the intersection of the ends of the rear-stage radiation protection shielding tube (52) and the front-stage radiation protection shielding tube (51) to fix the gap formed between the tube walls of the rear-stage radiation protection shielding tube (52) and the front-stage radiation protection shielding tube (51); the ends of the rear-stage radiation protection shielding tube (52) and the front-stage radiation protection shielding tube (51) are respectively connected to the gas guide inclined plate (60) to form an air outlet channel of the secondary air inlet (12); and the rear-stage radiation protection shielding tube (52) and the front-stage radiation protection shielding tube (51) are both made of insulating material.

7. A cryopump for low-temperature surface uniform adsorption according to claim 6, characterized in that: A guide baffle (80) is also provided in the rear-stage radiation protection shielding tube (52), and the guide baffle (80) is provided on the air outlet path of the secondary air inlet (12), one end of the guide baffle (80) is fixed to the inner tube wall of the rear-stage radiation protection shielding tube (52), and the other end extends toward the low-temperature array.

8. A cryopump for low-temperature surface uniform adsorption according to claim 7, characterized in that: The guide baffle (80) is electrically connected to a motor, and the motor controls the inclination angle of the guide baffle (80), thereby guiding the air outlet of the secondary air inlet (12) to flow toward the low-temperature surface box (40) and / or the low-temperature surface group (30).

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