Gas bearing assembly for an EUV light source

Patent metadata

Field	Value
Publication number	US-9422978-B2
Application number	US-201414310632-A
Country	US
Kind code	B2
Filing date	Jun 20, 2014
Priority date	Jun 22, 2013
Publication date	Aug 23, 2016
Grant date	Aug 23, 2016

Abstract

A gas bearing assembly including: a stator, a spindle rotatable about an axis, a first space between the spindle and the stator and arranged to receive a bearing gas at a first pressure, to support rotation of the spindle about the axis, a first annulus, in the stator or the spindle and arranged to vent the bearing gas from a first portion of the first space, a second annulus, in the stator or the spindle, and arranged to transport a barrier gas, at a second pressure, into a second portion of the first space, and a third annulus, in the stator or the spindle, the third annulus disposed between the first and second annuli and arranged to transport the bearing gas and the barrier gas out of a third portion of the space to a create, in the third portion, a third pressure less than the first and second pressures.

First claim

What is claimed is:

1. A gas bearing assembly for an EUV light source, comprising:
a stator body;
a spindle rotatable about the stator body with respect to an axis of rotation;
a first space between the spindle and the stator body and arranged to receive a bearing gas, at a first pressure, to support rotation of the spindle about the axis of rotation;
a first annular groove, in the stator body or the spindle, in fluid communication with the space and arranged to vent the bearing gas from a first portion of the first space;
a second annular groove, in the stator body or the spindle, in fluid communication with the space and arranged to transport a barrier gas, at a second pressure, into a second portion of the first space; and,
a third annular groove, in the stator body or the spindle, in fluid communication with the first space, wherein the third annular groove is:
disposed between the first and second annular grooves in an axial direction parallel to the axis of rotation; and,
arranged to transport the bearing gas and the barrier gas out of a third portion of the space to a create, in the third portion, a third pressure less than the first pressure and the second pressure.

2. The gas bearing assembly recited in claim 1 , wherein the first space is located between the spindle and the stator body in a radial direction orthogonal to the axis of rotation.

3. The gas bearing assembly recited in claim 1 , further comprising a vent channel open to the first annular groove and arranged to vent the bearing gas from the first portion of the first space.

4. The gas bearing assembly recited in claim 3 , further comprising:
a second space at a substantially ambient atmospheric pressure, wherein the vent channel is arranged to vent the bearing gas to the second space.

5. The gas bearing assembly recited in claim 1 , further comprising:
A vacuum channel with a first end and a second end open to the third annular groove; and,
a vacuum pump connected to the first end of the vacuum channel and arranged to extract the bearing gas and the barrier gas from the third portion of the first space.

6. The gas bearing assembly recited in claim 1 , further comprising:
A barrier gas channel with a first end and a second end open to the second annular groove; and,
a pump connected to the first end of the barrier gas channel and arranged to pump the barrier gas into the second portion of the first space.

7. The gas bearing assembly recited in claim 1 , wherein the first annular groove is arranged in the stator body.

8. The gas bearing assembly recited in claim 1 , wherein the second annular groove is arranged in the stator body.

9. The gas bearing assembly recited in claim 1 , wherein the third annular groove is arranged in the stator body.

10. The gas bearing assembly recited in claim 1 , wherein the first annular groove is arranged in the spindle.

11. The gas bearing assembly recited in claim 1 , wherein the second annular groove is arranged in the spindle.

12. The gas bearing assembly recited in claim 1 , wherein the third annular groove is arranged in the spindle.

13. The gas bearing assembly recited in claim 1 , wherein the bearing gas is selected from the group consisting of: nitrogen, oxygen, purified air, xenon, and argon.

14. The gas bearing assembly recited in claim 1 , wherein the barrier gas is selected from the group consisting of: xenon and argon.

15. A gas bearing assembly for an EUV light source, comprising:
a stator body including:
a first annular groove:
in fluid communication with a first portion of a space between the stator body and the spindle; and,
arranged to passively vent a bearing gas from the first portion;

a second annular groove in fluid communication with a second portion of the space; and,
a third annular groove in fluid communication with a third portion of the space, wherein the third annular groove is disposed between the first and second annular grooves in an axial direction parallel to the axis of rotation;

a spindle rotatable about the stator body with respect to an axis of rotation;
a pump in communication with the second annular groove and arranged to inject a barrier gas into the second portion via the second annular groove; and,
a vacuum pump in fluid communication with the third annular groove and arranged to extract the bearing gas and the barrier gas from a third portion of the space to a create, in the third portion, a first pressure, wherein:
the bearing gas is injected into the first portion at a second pressure, greater than the first pressure, to support rotation of the spindle with respect to the stator body.

16. A method for operating a gas bearing assembly for an EUV light source, comprising:
injecting a bearing gas at a first pressure into a first space between a spindle and a stator body;
supporting, with the injected bearing gas, rotation the spindle with respect to the stator body;
venting the bearing gas from a first portion of the first space through a first annular groove in the stator body or the spindle;
injecting a barrier gas at a second pressure into a second portion of the first space via a second annular groove in the stator body or the spindle;
extracting the bearing gas and the barrier gas from a third portion of the first space via a third annular groove, in the stator body or the spindle, wherein the third annular groove is disposed between the first and second annular grooves in an axial direction parallel to an axis of rotation of the spindle; and,
creating, in the third portion, a third pressure less than the first pressure and the second pressure.

17. The method recited in claim 16 , wherein venting the bearing gas from a first portion includes venting the bearing gas through a vent channel, in fluid communication with the first annular groove.

18. The method recited in claim 17 , wherein venting the bearing gas through the vent channel includes venting the bearing gas to a second space at a substantially ambient atmospheric pressure.

19. The method recited in claim 16 , further comprising:
extracting, using a vacuum pump, the bearing gas and the barrier gas from the third portion through a channel with a first end connected to the vacuum pump and a second end open to the third annular groove.

20. The method recited in claim 16 , further comprising:
injecting, using a pump, the bearing gas to the second portion via a channel with a first end connected to the pump and a second end open to the second annular groove.

21. The method recited in claim 16 , wherein the first pressure is greater than the second pressure.

22. The method recited in claim 16 , wherein the bearing gas is selected from the group consisting of: nitrogen, oxygen, purified air, xenon, and argon.

23. The method recited in claim 16 , wherein the barrier gas is selected from the group consisting of: xenon and argon.

Assignees

• Kla Tencor Corp

Inventors

• Chilese Francis C
• Garcia Rudy F

Classifications

• F16C32/0614 Primary

  the gas being supplied under pressure, e.g. aerostatic bearings · CPC title

• F16C33/748

  flowing to or from the sealing gap, e.g. vacuum seals with differential exhaust · CPC title

• F16C32/0685

  for radial load only · CPC title

• F16C2380/18

  Handling tools for semiconductor devices · CPC title