IP Library Granted Patent US 10,823,943
Granted Patent B2
US 10,823,943 · App. 16/165,842 · Granted Nov 3, 2020

Plasma source with lamp house correction

Inventors: Shiyu Zhang (Fremont, CA); Ilya Bezel (Mountain View, CA)
Assignee: KLA Corporation
G02B17/0892G01N21/211G01N21/8806G03F7/70225G01N2021/213
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Quick Facts
Patent No.
US 10,823,943
App. No.
16/165,842
Granted
Nov 3, 2020
Kind
B2
Abstract

A plasma light source with lamp house correction is disclosed. The system may include a pump source configured to generate pump illumination. The pump illumination may be directed, by an elliptical reflector element, to a volume of gas contained within a plasma lamp in order to generate a plasma. The plasma may be configured to generate broadband illumination. The system may also include a correction plate and/or an aspherical elliptical reflector element configured to alter the pump illumination to correct for aberrations introduced by the plasma lamp. The system may also include an additional aspherical correction plate configured to alter the broadband illumination to correct for aberrations introduced by optical elements of the system.

Claims (213)

1. A system, comprising:

a pump source configured to generate pump illumination;

a correction plate configured to receive the pump illumination and modify one or more characteristics of the pump illumination in order to correct one or more aberrations of the pump illumination introduced by one or more optical elements of the system; and

a reflector element configured to receive the pump illumination and direct the pump illumination to a volume of gas contained within a plasma lamp, wherein the plasma lamp is configured to sustain a plasma within the volume of gas to generate broadband illumination.

2. The system of claim 1 , wherein the plasma lamp comprises a cylindrical plasma lamp.

3. The system of claim 1 , wherein the reflector element comprises an aspherical reflector element.

4. The system of claim 3 , wherein the surface profile of the aspherical reflector element is described by the equation

z

=

cr

2

1

+

1

-

(

1

+

k

)

c

2

r

2

+

i

=

1

n

a

i

r

i

.

5. The system of claim 1 , wherein the plasma lamp comprises a substantially prolate spheroid-shaped plasma lamp.

6. The system of claim 1 , wherein the correction plate comprises an aspherical correction plate configured to correct one or more aberrations of the pump illumination introduced by the plasma lamp.

7. The system of claim 6 , wherein the surface profile of the correction plate is described by the equation

z

=

cr

2

1

+

1

-

(

1

+

k

)

c

2

r

2

+

i

=

1

n

a

i

r

i

.

8. The system of claim 1 , further comprising a compensator plate configured to receive the pump illumination and direct the pump illumination toward the reflector element.

9. The system of claim 1 , further comprising the one or more optical elements and a homogenizer, wherein the one or more optical elements are configured to receive the broadband illumination from the plasma lamp and direct the broadband illumination to the homogenizer.

10. The system of claim 1 , wherein the pump source comprises a fiber laser pump source.

11. The system of claim 1 , further comprising a cold mirror configured to receive the broadband illumination and direct the broadband illumination to a second correction plate.

12. The system of claim 1 , wherein the correction plate comprises a first correction plate and a second correction plate, wherein the first correction plate includes one or more odd aspheric correction terms, and the second correction plate includes one or more cylindrical correction terms.

13. The system of claim 1 , wherein the correction plate includes a surface having one or more odd aspheric correction terms and one or more cylindrical correction terms.

14. A system, comprising:

a broadband illumination source, wherein the broadband illumination source comprises:

a pump source configured to generate pump illumination;

a correction plate configured to receive the pump illumination and modify one or more characteristics of the pump illumination; and

a reflector element configured to receive the pump illumination and direct the pump illumination to a volume of gas contained within a plasma lamp, wherein the plasma lamp is configured to sustain a plasma within the volume of gas to generate broadband illumination;

a detector assembly; and

a set of characterization optics configured to collect at least a portion of the broadband illumination from the broadband illumination source and direct the broadband illumination onto a sample, wherein the set of characterization optics is further configured to direct radiation from the sample to the detector assembly.

15. A system, comprising:

a pump source configured to generate pump illumination;

a first correction plate configured to receive the pump illumination and modify one or more characteristics of the pump illumination;

a reflector element configured to receive the pump illumination and direct the pump illumination to a volume of gas contained within a plasma lamp, wherein the plasma lamp is configured to sustain a plasma within the volume of gas to generate broadband illumination; and

a second correction plate configured to receive the broadband illumination and correct one or more aberrations of the broadband illumination, wherein the second correction plate comprises an aspherical correction plate.

16. The system of claim 15 , wherein the surface profile of the second correction plate is described by the equation

z

=

cr

2

1

+

1

-

(

1

+

k

)

c

2

r

2

+

i

=

1

n

a

i

r

i

.

17. A system, comprising:

a broadband illumination source, wherein the broadband illumination source comprises:

a pump source configured to generate pump illumination;

a first correction plate configured to receive the pump illumination and modify one or more characteristics of the pump illumination;

a reflector element configured to receive the pump illumination and direct the pump illumination to a volume of gas contained within a plasma lamp, wherein the plasma lamp is configured to sustain a plasma within the volume of gas to generate broadband illumination; and

a second correction plate configured to receive the broadband illumination and correct one or more aberration of the broadband illumination, wherein the second correction plate comprises an aspherical correction plate;

a detector assembly; and

a set of characterization optics configured to collect at least a portion of the broadband illumination from the broadband illumination source and direct the broadband illumination onto a sample, wherein the set of characterization optics is further configured to direct radiation from the sample to the detector assembly.

18. A method, comprising:

generating pump illumination;

correcting the pump illumination with a first correction plate;

collecting and focusing the pump illumination to a volume of gas contained within a plasma lamp with a reflector element;

generating a plasma within the volume of gas contained within the plasma lamp;

generating broadband illumination with the plasma; and

correcting one or more aberrations of the broadband illumination with a second correction plate.

19. The method of claim 18 , wherein the plasma lamp comprises a cylindrical plasma lamp.

20. The method of claim 18 , wherein the reflector element comprises an aspherical reflector element.

21. The method of claim 18 , wherein the surface profile of the reflector element is described by the equation

z

=

cr

2

1

+

1

-

(

1

+

k

)

c

2

r

2

+

i

=

1

n

a

i

r

i

.

22. The method of claim 18 , wherein the plasma lamp comprises a substantially prolate spheroid-shaped plasma lamp.

23. The method of claim 18 , wherein the first correction plate comprises an aspherical correction plate configured to correct one or more aberrations of the pump illumination introduced by the plasma lamp.

24. The method of claim 23 , wherein the surface profile of the first correction plate is described by the equation

z

=

cr

2

1

+

1

-

(

1

+

k

)

c

2

r

2

+

i

=

1

n

a

i

r

i

.

25. The method of claim 18 , further comprising compensating the pump illumination with a compensator plate.

26. The method of claim 18 , further comprising directing the broadband illumination to a homogenizer via one or more optical elements.

27. The method of claim 18 , wherein the generating pump illumination comprises generating pump illumination with a fiber laser pump source.

Assignments (2)
CHANGE OF NAME Recorded Sep 16, 2020
From: KLA-TENCOR CORPORATION
To: KLA CORPORATION
Reel/Frame 053787/0974 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Mar 6, 2019
From: ZHANG, SHIYU; BEZEL, ILYA
To: KLA-TENCOR CORPORATION
Reel/Frame 048519/0339 →
Continuity (2)
Provisional Application 62712391 · Jul 31, 2018
Related Publication 20200041774A1 · Feb 6, 2020