# US 2016/0255708 A1 · Extreme ultraviolet light source > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2016/0255708 A1 - Document ID: US20160255708A1 - Status: Published application - Kind: A1 - Application number: 15/148,255 - Filed: 2016-05-06 - Published: 2016-09-01 - Earliest claimed: 2014-07-07 - Assignees: ASML Netherlands B.V. - Applicants: ASML Netherlands B.V. - Inventors: Yezheng Tao; John Tom Stewart, IV; Jordan Jur; Daniel Brown - Web page: https://patentgrep.com/patent/US20160255708A1 ## CPC - H05G 2/0088: {for preconditioning the plasma generating material} - Y02E 30/10: Nuclear fusion reactors - H05G: X-RAY TECHNIQUE (investigating or analysing materials by the use of X-rays G01N23/00; apparatus for X-ray photography G03B42/02; X-ray tubes H01J35/00; TV systems having X-ray input H04N5/321) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## 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. ## Claims ### Claim 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. ### Claim 2 (depends on 1) 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. ### Claim 3 (depends on 1) 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. ### Claim 4 (depends on 1) 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. ### Claim 5 (depends on 4) The method of claim 4, wherein the first peak energy is 1-10% of the second peak energy. ### Claim 6 (depends on 4) 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. ### Claim 7 (depends on 1) 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. ### Claim 8 (depends on 1) 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. ### Claim 9 (depends on 8) The method of claim 8, wherein the target material droplet is substantially spherical and has a diameter of 17-35 μm. ### Claim 10 (depends on 8) The method of claim 8, wherein the diameter is less than 30 μm. ### Claim 11 (depends on 1) The method of claim 1, wherein the modified target comprises a collection of pieces of target material in a volume. ### Claim 12 (depends on 11) The method of claim 11, wherein the volume is substantially an ellipsoid. ### Claim 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. ### Claim 14 (depends on 13) 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. ### Claim 15 (depends on 14) 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. ### Claim 16 (depends on 15) The method of claim 15, wherein the initial target is substantially spherical and has a diameter of 17-35 μm. ### Claim 17 (depends on 13) The method of claim 13, wherein the extent of the target in the second direction is between 300 μm and 350 μm. ### Claim 18 (depends on 13) The method of claim 13, wherein the extent of the target in the second direction is between 300 μm and 500 μm. ### Claim 19 (depends on 17) The method of claim 17, wherein the extent of the target in the first direction is between 50 nm to 200 nm. ### Claim 20 (depends on 13) 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. ### Claim 21 (depends on 13) The method of claim 13, wherein the target comprises a collection of pieces of target material in a volume.