Search

KR-102962146-B1 - Cryopump

KR102962146B1KR 102962146 B1KR102962146 B1KR 102962146B1KR-102962146-B1

Abstract

The cryopump comprises a pump inlet; a two-stage chiller; a first-stage array thermally coupled to the first stage of the two-stage chiller; and a cryopanel structure coupled to the second stage of the two-stage chiller. The surface of the cryopanel structure comprises a coated portion having an adsorbent material and an additional portion not coated with the adsorbent material.

Inventors

  • 샤렉 제럴드

Assignees

  • 에드워즈 배큠 엘엘시

Dates

Publication Date
20260508
Application Date
20210706
Priority Date
20200708

Claims (10)

  1. In cryopumps, Pump inlet; 2-stage chiller; A first stage array thermally coupled to the first stage of the above two-stage refrigerator; and It includes a cryopanel structure coupled to the second stage of the above two-stage refrigerator and comprising a plurality of cryopanels, and Each of the above plurality of cryopanels comprises two surfaces, wherein the two surfaces include a coated surface coated with an adsorbent material and an additional surface not coated with said adsorbent material; The first stage array includes a plurality of elements corresponding to the plurality of cryopanels; The plurality of elements are configured to be mounted between the pump inlet and the plurality of cryopanels; Each of the plurality of elements extends toward an adjacent cryopanel from a position between the corresponding cryopanel and the pump inlet and is inclined toward the inlet, so that each of the plurality of elements at least partially shields the coating surface of the adjacent cryopanel from direct collision with gas molecules passing through the pump inlet. Cryopump.
  2. In Article 1, The above cryopanel structure is configured and mounted such that the surface of the cryopanel structure, where molecules entering the cryopump are most likely to collide first, becomes the additional part of the surface of the cryopanel structure. Cryopump.
  3. In Article 1, The first stage array and the cryopanel structure are configured such that there is no line of sight path between the coated portion of the surface of the cryopanel and the pump inlet. Cryopump.
  4. In Article 1, The plurality of cryopanels comprises a plurality of planar cryopanels, one side of the cryopanel comprises the coating surface, and the other side comprises the additional surface. Cryopump.
  5. In Article 1, The plurality of cryopanels comprises a plurality of coaxial cylindrical cryopanels of different diameters. Cryopump.
  6. In Article 5, The outer surface of the above-described cylindrical cryopanel includes the coating surface, and the inner surface includes the additional surface. Cryopump.
  7. In Article 5, The plurality of elements of the first stage array include a plurality of coaxial truncated conical elements of different diameters. Cryopump.
  8. In any one of paragraphs 1 to 7, The above-mentioned adsorbent material is configured to adsorb Type III gases such as hydrogen, helium, and neon. Cryopump.
  9. In any one of paragraphs 1 to 7, The above-mentioned adsorbent material comprises a molecular sieve that coats the coating surface. Cryopump.
  10. In any one of paragraphs 1 to 7, The above adsorbent material comprises one of charcoal, activated carbon, zeolite, or a porous metal surface. Cryopump.

Description

Cryopump The field of the present invention relates to cryopumps, and in particular to two-stage cryopumps having a first stage of temperature for capturing a type I gas such as water vapor, and a second stage of low temperature for capturing a type II gas such as nitrogen and, in some embodiments, for freeze-adsorbing a type III gas such as hydrogen. The two-stage cryopump is formed by a low-temperature second-stage cryopanel array. This can operate in the range of 4 to 25 Kelvin (K) and can be coated with a capture material such as charcoal. This cryopanel array serves as a primary pumping surface and is surrounded by a first-stage radiation shield, which operates in a high-temperature range such as 40 to 130 K, provides radiation shielding to the low-temperature array, and shields the array from Type I gases such as water vapor by capturing these gas molecules in contact with the array. During operation, as gas passes through the inlet into the pump vessel, at least some of the Type I gases, such as water vapor, condense on the front array forming part of the first stage radiation shield. Gases with lower boiling points pass through the front array and enter the volume within the radiation shield. Type II gases, such as nitrogen, condense on the second stage array, while Type III gases, such as hydrogen, helium, and neon, which have a vapor pressure detectable at 4K, are adsorbed by an adsorbent such as activated carbon, zeolite, or a molecular sieve coating the second stage cryopanel. In this way, gas entering the pump from the chamber is captured, and a vacuum is created within the pump vessel. One problem with the cryopump is that its ability to capture gas molecules decreases as the capture surface becomes saturated with gas molecules during operation. Therefore, the cryopump is periodically regenerated to release the captured gas molecules. It would be desirable to provide a two-stage cryopump with increased operating time between regenerations. A first embodiment provides a cryopump, comprising: a pump inlet; a two-stage chiller; a first-stage array thermally coupled to a first stage of the two-stage chiller; and a cryopanel structure coupled to a second stage of the two-stage chiller and comprising a plurality of cryopanels, wherein each of the plurality of cryopanels comprises two surfaces, wherein the two surfaces comprise a coated surface coated with an adsorbent material and an additional surface not coated with said adsorbent material; the first-stage array comprises a plurality of elements corresponding to the plurality of cryopanels; and the plurality of elements are configured to be mounted between the pump inlet and the plurality of cryopanels. Each of the plurality of elements extends toward an adjacent cryopanel from a position between the corresponding cryopanel and the pump inlet and is inclined toward the inlet, so that each of the plurality of elements at least partially shields the coating surface of the adjacent cryopanel from direct collision of gas molecules passing through the pump inlet. The inventors of the present invention recognized that the adsorbent coating surface of a cryopump may become less effective over time because gas molecules are adsorbed onto the surface. Adsorbent materials are provided to capture Type III gases, and it is important that these gases are captured upon contact with this surface. However, to increase the time between regeneration cycles, it is desirable to suppress any other gases captured by the adsorbent that may condense on other surfaces. For example, photoresist is a gas that may be present when the cryopump is used to evacuate a semiconductor processing chamber, and this is adsorbed by the adsorbent surface upon impact, which reduces the lifespan between regeneration cycles. The inventors of the present invention recognized that there are uncoated parts of the second-stage cryopanel surface, and that gases such as photoresist that first collide with these surfaces condense on the uncoated surfaces before reaching the adsorbent-coated surface, thereby increasing the lifespan of the adsorbent-coated surface. Generally, pump designers attempt to coat all surfaces of the cryopanel, as this increases the area covered by the adsorbent, thereby increasing the pump speed and the time between regeneration. However, the design of the pump must consider the surface area coated with the adsorbent because it reflects the amount of hydrogen that can be adsorbed and affects safety functions. Therefore, by providing a pump with some surfaces that are not coated, gases other than Type III gases can condense when they collide with these uncoated surfaces, whereas Type III gases bounce off the uncoated surfaces and are adsorbed when they collide with the coated surfaces. In this way, the surfaces of the adsorbents will primarily adsorb Type III gases, which will increase efficiency and the lifespan between regenerations. By allowing at least some of the gase