Search

EP-4737733-A1 - VACUUM EVACUATION DEVICE

EP4737733A1EP 4737733 A1EP4737733 A1EP 4737733A1EP-4737733-A1

Abstract

Provided is a vacuum exhaust device that can be plasma-cleaned favorably without providing a pressure regulation valve. A vacuum exhaust device 10 having a turbo molecular pump 100 and a plasma generation device 210 includes a throttle portion 244 capable of increasing an internal pressure of the plasma generation device 210 so as to satisfy a relationship of P ≥ 0.3 / D where P is pressure [Pa] and D is a distance [m] between electrodes of the plasma generation device. Further, the internal pressure of the plasma generation device 210 can be increased by the throttle portion to a pressure that satisfies a relationship of P ≤ 1.5 / D .

Inventors

  • KABASAWA TAKASHI

Assignees

  • Edwards Japan Limited

Dates

Publication Date
20260506
Application Date
20240624

Claims (7)

  1. A vacuum exhaust device having a vacuum pump and a plasma generation device, the vacuum exhaust device comprising a throttle capable of increasing an internal pressure of the plasma generation device so as to satisfy a relationship of P ≥ 0.3 / D where P is pressure [Pa] and D is a distance [m] between electrodes of the plasma generation device.
  2. The vacuum exhaust device according to claim 1, wherein the internal pressure of the plasma generation device can be increased by the throttle to a pressure that satisfies a relationship of P ≤ 1.5 / D .
  3. The vacuum exhaust device according to claim 1 or 2, wherein the throttle is disposed in a connecting portion between the vacuum pump and the plasma generation device.
  4. The vacuum exhaust device according to claim 1 or 2, wherein the throttle is an orifice.
  5. The vacuum exhaust device according to claim 1 or 2, wherein the throttle includes a hole that is inclined in a direction intersecting a radial direction of the vacuum pump.
  6. The vacuum exhaust device according to claim 1 or 2, wherein the throttle is coated with ceramic.
  7. The vacuum exhaust device according to claim 1 or 2, wherein the throttle is treated with alumite.

Description

[Technical Field] The present invention relates to a vacuum exhaust device including a vacuum pump such as a turbo molecular pump, for example. [Background Art] A turbo molecular pump is generally known as a type of vacuum pump. For example, a turbo molecular pump is used as an exhaust in a device for manufacturing a semiconductor, a flat panel, or the like. In the turbo molecular pump, gas (process gas) that has been sucked into a pump main body is exhausted by applying a current to a motor in the pump main body in order to rotate rotor blades, whereby gas molecules of the gas are flicked away. This type of turbo molecular pump may also include a heater and a cooling pipe in order to manage an internal temperature of the pump appropriately. In a vacuum pump such as a turbo molecular pump, a reaction product generated during the process for manufacturing a semiconductor or the like may accumulate inside the vacuum pump. PTL 1, cited below, discloses a technique for disposing a plasma generation device in a vacuum pump in order to plasma-clean the interior as a countermeasure against reaction products. PTL 1 also discloses a technique for disposing the plasma generation device on a side surface of the vacuum pump. In the invention described in PTL 1, a plasma source is disposed in a lead-in port disposed in the side surface of the vacuum pump. A valve disposed between the plasma source and the vacuum pump controls a supply of radicals. [Citation List] [Patent Literature] [PTL 1] Japanese Patent Application Publication No. 2022-017864 [Summary of Invention] [Technical Problem] In a plasma generation device such as that disclosed in PTL 1, a raw material gas such as NF3 or CF4 flows between discharged electrodes, whereby the raw material gas is ionized. In this case, a discharge voltage between the electrodes takes a minimum value in the vicinity of a condition where a value of inter-electrode distance × pressure is 0.5 Pa·m (Paschen's law). Conventionally, therefore, although not shown in the figures, a valve (a pressure regulation valve, a valve device) is disposed near an outlet port of the vacuum pump, and pressure regulation is performed by controlling the valve so that the above condition is established between the electrodes of the plasma generation device. As a result, the following problems occur. (1) Disposing the pressure regulation valve near the outlet port requires installation space and involves cost.(2) Since the pressure regulation valve is disposed on the downstream side of the vacuum pump, the entire interior of the vacuum pump has to be set at high pressure, leading to a reduction in a flow speed of radicals generated by the plasma generation device. As a result, a reaching distance of the radicals decreases (shortens). It is envisaged, for example, that approximately 90% of a degree of activity of the radicals is lost such that the degree of activity falls to approximately 10%. Further, during an operation of the vacuum pump, a pressure near the plasma generation device is reduced by the exhaust action of the vacuum pump, and therefore, with a method of disposing a valve downstream of the vacuum pump, it may be impossible to increase the pressure near the plasma generation device as desired. In order to increase the pressure near the plasma generation device to a desired pressure, a pressure near the outlet port of the vacuum pump has to be greatly increased, and as a result, in certain cases, the vacuum pump may overheat. Hence, with a conventional structure, it may be necessary to reduce a rotation speed of the vacuum pump or stop the vacuum pump in order to weaken an exhaust action of the pump.(3) When a valve is not provided between the plasma generation device and the pump, unlike in the invention described in PTL 1, there is nothing to prevent reaction products from infiltrating the plasma generation device (accumulating in the plasma generation device). An object of the present invention is to provide a vacuum exhaust device that can be plasma-cleaned favorably without providing a pressure regulation valve. [Solution to Problem] To achieve the object described above, a vacuum exhaust device according to the present invention is a vacuum exhaust device having a vacuum pump and a plasma generation device, the vacuum exhaust device including a throttle capable of increasing an internal pressure of the plasma generation device so as to satisfy a relationship of P≥0.3/D where P is pressure [Pa] and D is a distance [m] between electrodes of the plasma generation device. [Advantageous Effects of Invention] According to the invention described above, it is possible to provide a vacuum exhaust device that can be plasma-cleaned favorably without providing a pressure regulation valve. [Brief Description of Drawings] [Fig. 1] Fig. 1 is a schematic illustrative view showing a configuration of a vacuum exhaust device according to an embodiment of the present invention.[Fig. 2] Fig. 2 is a circuit