Extreme ultraviolet light source

Patent metadata

Field	Value
Publication number	US-2016255708-A1
Application number	US-201615148255-A
Country	US
Kind code	A1
Filing date	May 6, 2016
Priority date	Jul 7, 2014
Publication date	Sep 1, 2016
Grant date	—

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 of generating extreme ultraviolet (EUV) light, the method comprising:
providing a target to a target location, the target comprising target material that emits EUV light when in a plasma state, the target having 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; and directing radiation toward the target location to interact the radiation with the target, the radiation comprising a first portion and a second portion, the second portion reaching the target location after the first portion, the radiation propagating in a direction that is parallel to the first direction at the target location, wherein interacting the first portion of the radiation with the target forms a modified target, the modified target having a lower density than the target, and interacting the second portion of the radiation with the modified target converts at least some of the target material in the modified target to the plasma that emits EUV light.

2 . The method of claim 1 , wherein the extent of the target in the first direction is between 50 nm to 200 nm, and the extent of the target in the second direction is between 300 μm and 350 μm.

3 . The method of claim 1 , wherein the extent of the target in the first direction is between 50 nm to 200 nm, and the extent of the target in the second direction is between 300 μm and 500 μm.

4 . The method of claim 1 , wherein the first and second portions of the radiation are part of a single pulse of radiation, the first portion of the radiation is associated with a first peak energy, and the second portion of the radiation is associated with a second peak energy, the second peak energy being greater than the first peak energy.

5 . The method of claim 4 , wherein the first peak energy is 1-10% of the second peak energy.

6 . The method of claim 4 , wherein the first portion of the radiation has a duration of 50-150 ns, and the first peak energy is 5 milliJoules (mJ) or less.

7 . The method of claim 1 , wherein the first portion of the radiation is a first pulse of radiation, and the second portion of the radiation is a second pulse of radiation.

8 . The method of claim 1 , wherein providing the target to a target location comprises:
providing a target material droplet to an initial target location; and directing a pulse of radiation toward the initial target location such that the pulse of radiation and the target material droplet interact to form the target.

9 . The method of claim 8 , wherein the target material droplet is substantially spherical and has a diameter of 17-35 μm.

10 . The method of claim 8 , wherein the diameter is less than 30 μm.

11 . The method of claim 1 , wherein the modified target comprises a collection of pieces of target material in a volume.

12 . The method of claim 11 , wherein the volume is substantially an ellipsoid.

13 . A method of generating extreme ultraviolet (EUV) light, the method comprising:
providing a target to a target location, the target comprising target material that emits EUV light when in a plasma state, the target having 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; and directing an amplified light beam toward the target location to interact the radiation with the target, an interaction between the amplified light beam and the target converting at least some of the target material in the modified target to the plasma that emits EUV light.

14 . The method of claim 13 , further comprising:
providing an initial target to an initial target location; and providing a pulse of radiation to the initial target location, wherein an interaction between the pulse of radiation and the initial target modifies a geometric distribution of target material of the initial target such that the target is provided to the target location.

15 . The method of claim 14 , wherein the greatest extent of the initial target is smaller than the extent of the target in the second direction.

16 . The method of claim 15 , wherein the initial target is substantially spherical and has a diameter of 17-35 μm.

17 . The method of claim 13 , wherein the extent of the target in the second direction is between 300 μm and 350 μm.

18 . The method of claim 13 , wherein the extent of the target in the second direction is between 300 μm and 500 μm.

19 . The method of claim 17 , wherein the extent of the target in the first direction is between 50 nm to 200 nm.

20 . The method of claim 13 , wherein:
the amplified light beam comprises a first portion and a second portion, the second portion reaching the target location after the first portion, interacting the first portion of the radiation with the target forms a modified target, and interacting the second portion of the radiation with the modified target converts at least some of the target material in the modified target to the plasma that emits EUV light.

21 . The method of claim 13 , wherein the target comprises a collection of pieces of target material in a volume.

Assignees

• Asml Netherlands Bv

Inventors

• Tao Yezheng
• Stewart Iv John Tom
• Jur Jordan
• Brown Daniel

Classifications

• 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

• H05G2/008 Primary

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

• H05G2/0088 Primary

  for preconditioning the plasma generating material · CPC title