Extreme ultraviolet light source

Patent metadata

Field	Value
Publication number	US-10064261-B2
Application number	US-201715790408-A
Country	US
Kind code	B2
Filing date	Oct 23, 2017
Priority date	Jul 7, 2014
Publication date	Aug 28, 2018
Grant date	Aug 28, 2018

Abstract

An initial pulse of radiation is generated; a section of the initial pulse of radiation is extracted to form a modified pulse of radiation, the modified pulse of radiation including a first portion and a second portion, the first portion being temporally connected to the second portion, and the first portion having a maximum energy that is less than a maximum energy of the second portion; the first portion of the modified pulse of radiation is interacted with a target material to form a modified target; and the second portion of the modified pulse of radiation is interacted with the modified target to generate plasma that emits extreme ultraviolet (EUV) light.

First claim

What is claimed is:

1. A method comprising:
directing an optical pulse toward an optical element;
controlling the optical element to form a modified optical pulse from the optical pulse, the modified optical pulse comprising a first portion and a second portion, the second portion having a temporal energy profile based on a temporal energy profile of the optical pulse, and the first portion having a temporal profile that is different from the temporal energy profile of the optical pulse, wherein one or more characteristics of the modified optical pulse are at least partially determined by controlling the optical element; and
interacting the modified optical pulse with a target comprising target material, wherein an interaction between the second portion of the modified optical pulse and the target converts at least some of the target material to a plasma that emits extreme ultraviolet (EUV) light.

2. The method of claim 1 , wherein the one or more characteristics of the modified optical pulse comprise a temporal duration, a peak energy, and/or the temporal energy profile of the first portion of the modified optical pulse.

3. The method of claim 2 , wherein the target is a modified target, and further comprising interacting a pre-pulse optical pulse with an initial target to form the modified target.

4. The method of claim 3 , wherein the modified target has a first extent along a first direction, the first direction being parallel to a direction of propagation of the second portion of the modified optical pulse, the one or more characteristics of the modified optical pulse comprise a temporal duration, and controlling the optical element to form the modified optical pulse comprises controlling the temporal duration of the second portion of the modified optical pulse based on the first extent of the modified target.

5. The method of claim 4 , wherein the temporal duration of the second portion of the modified target is inversely related to the first extent of the modified target.

6. The method of claim 1 , wherein interacting the first portion of the modified optical pulse with the target comprising target material modifies a geometric distribution of the target material in at least two dimensions.

7. The method of claim 6 , wherein the geometric distribution of the target material increases in at least one of the at least two dimensions.

8. The method of claim 1 , wherein an interaction between the first portion of the modified optical pulse and the target modifies a geometric distribution of the target material to form a modified target, the modified target occupying a larger volume than the target, the modified target comprising at least a region that has a lower density than the target, and the second portion of the modified optical pulse interacts with the modified target to form the plasma that emits EUV light.

9. The method of claim 1 , wherein controlling an optical element comprises applying a voltage to an electro-optic modulator (EOM).

10. A system for an extreme ultraviolet (EUV) light source, the system comprising:
a light generation module;
an optical element; and
a control system configured to determine one or more characteristics of a modified optical pulse formed from an optical pulse produced by the light generation module, wherein the modified optical pulse comprises a first portion and a second portion, the second portion has a temporal energy profile based on a temporal energy profile of the optical pulse, the first portion has a temporal profile that is different from the temporal energy profile of the optical pulse, and the second portion has an energy sufficient to convert at least some target material in a target to a plasma that emits EUV light.

11. The EUV light source of claim 10 , wherein the optical element comprises an electro-optic modulator (EOM).

12. The EUV light source of claim 10 , further comprising a second light generation module, the second light generation module being configured to emit a second optical pulse.

13. The EUV light source of claim 12 , further comprising a beam combiner configured to interact with the modified optical pulse and the second optical pulse, and to direct the modified optical pulse and the second optical pulse to a vessel configured to receive a target.

14. The EUV light source of claim 13 , wherein the light generation module comprises a carbon dioxide (CO2) laser, and the second light generation module comprises a solid state laser.

15. The EUV light source of claim 14 , wherein the modified optical pulse comprises light having a wavelength of 10.6 microns (μm), and the second optical pulse comprises light having a wavelength of 1.06 μm.

16. The EUV light source of claim 12 , wherein the modified optical pulse comprises light having 10.6 microns (μm), and the second optical pulse comprises light having a wavelength of 10.6 μm.

17. The EUV light source of claim 16 , wherein the light generation module and the second light generation module are part of a single light source.

18. The EUV light source of claim 16 , wherein the light generation module and the second light generation module are distinct and separate light sources.

19. An EUV light source comprising:
a light generation module;
an optical element;
a vessel configured to receive a target comprising target material that emits EUV light when in a plasma state; and
a control system configured to determine one or more characteristics of a modified optical pulse formed by the optical element based on an optical pulse produced by the light generation module, wherein the modified optical pulse comprises a first portion and a second portion, the second portion has a temporal energy profile based on a temporal energy profile of the optical pulse, the first portion has a temporal profile that is different from the temporal energy profile of the optical pulse, and the second portion has an energy sufficient to convert at least some target material in a target to a plasma that emits EUV light.

20. An EUV light source comprising:
a light generation module configured to emit an optical pulse;
an optical element configured to form a main pulse of light from the optical pulse, the main pulse of light being a single pulse of radiation having a first portion and a second portion, the second portion having a temporal energy profile that is based on a temporal energy profile of the optical pulse, and the first portion having a temporal energy profile that is different from the temporal energy profile of the optical pulse; and
a vessel comprising a target region configured to receive a target, wherein the target comprises target material that emits EUV light when in a plasma state, and the target has an extent in a first direction of 200 nanometers (nm) or less and an extent in a second direction of 300 micrometers (μm) or more.

21. The EUV light source of claim 20 , further comprising: a control system configured to control the optical element to determine one or more characteristics of the main pulse of light.

22. The EUV light source of claim 20 , further comprising: a target material supply system configured to supply the target to the vessel.

23. The EUV light source of claim 22 , wherein the target material supply system is configured to supply a droplet of molten metal to the vessel, and the EUV light source further comprises:
a second light generation module configured to emit an initial pulse of light, the initial pulse of light being confi

Assignees

• Asml Netherlands Bv

Inventors

• Tao Yezheng
• Stewart Iv John Tom
• Jur Jordan
• Brown Daniel
• Schafgans Alexander A
• Arcand Jason M
• Laforge Andrew

Classifications

• H05G2/006

  Electricity · mapped topic

• H05G2/008 Primary

  involving an energy-carrying beam in the process of plasma generation · CPC title

• G03F7/70041

  by pulsed sources, e.g. multiplexing, pulse duration, interval control or intensity control · CPC title

• G03F7/70033

  by plasma extreme ultraviolet [EUV] sources · CPC title

• H05G2/003

  the plasma being generated from a material in a liquid or gas state · CPC title