# US 12,769,140 B2 · Method and device for generating laser pulses > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,769,140 B2 - Document ID: US12769140B2 - Status: Granted - Kind: B2 - Application number: 18/605,858 - Filed: 2024-03-15 - Published: 2024-08-01 - Granted: 2026-10-20 - Earliest claimed: 2021-09-20 - Assignees: TRUMPF Lasersystems for Semiconductor Manufacturing GmbH - Applicants: TRUMPF Lasersystems for Semiconductor Manufacturing GmbH - Inventors: Joachim Schulz; Guenther Krauss - Web page: https://patentgrep.com/patent/US12769140B2 ## CPC - G02B 27/0905: {Dividing and/or superposing multiple light beams} - G02B 27/0977: {Reflective elements} - G02B 27/141: {using dichroic mirrors} - H05G 2/0084: {Control of the laser beam} - H05G 2/0086: {Optical arrangements for conveying the laser beam to the plasma generation location} - H01S 3/2232: {Carbon dioxide (CO2) or monoxide [CO]} - H01S 3/2316: {Cascaded amplifiers} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - 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) - H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL ## Abstract A method for generating laser pulses includes generating first laser pulses and second laser pulses using at least one laser source, and amplifying the first laser pulses and second laser pulses using an optical amplifier. Each respective second laser pulse passes through the optical amplifier offset in time in relation to a respective first laser pulse by a time offset. The method further includes separating the first laser pulses from the second laser pulses using an optical beam splitter based on at least one beam property, and passing the first laser pulses through a retardation unit. A time duration for each respective first laser pulse to pass through a retardation section of the retardation unit corresponds to the time offset. The method further includes superimposing the first laser pulses with the second laser pulses using a superposition unit to form superimposed laser pulses. ## Claims ### Claim 1 A method for generating laser pulses, the method comprising: generating first laser pulses and second laser pulses using at least one laser source; amplifying the first laser pulses and second laser pulses using an optical amplifier, wherein each respective second laser pulse passes through the optical amplifier offset in time in relation to a respective first laser pulse by a time offset; separating the first laser pulses from the second laser pulses using an optical beam splitter based on at least one beam property, in which the first laser pulses differ from the second laser pulses; passing the first laser pulses through a retardation unit, wherein a time duration for each respective first laser pulse to pass through a retardation section of the retardation unit corresponds to the time offset in relation to the respective second laser pulse, wherein the second laser pulses do not pass through the retardation unit; and superimposing the first laser pulses with the second laser pulses using a superposition unit to form superimposed laser pulses, wherein the superimposed laser pulses are used to generate extreme ultraviolet (EUV) radiation. ### Claim 2 (depends on 1) The method as claimed in claim 1, wherein the first laser pulses have a wavelength and/or a polarization state different from that of the second laser pulses. ### Claim 3 (depends on 1) The method as claimed in claim 1, wherein the generation of each respective second laser pulse takes place offset in time in relation to the generation of the respective first laser pulse. ### Claim 4 (depends on 1) The method as claimed in claim 1, wherein the first laser pulses are generated using a first laser source, and the second laser pulses are generated using a second laser source. ### Claim 5 (depends on 1) The method as claimed in claim 1, wherein each of the first laser pulses and the second laser pulses has a pulse duration between 10 ns and 200 ns. ### Claim 6 (depends on 1) The method as claimed in claim 1, wherein each second laser pulse is generated spaced apart from the respective first laser pulse by the time offset in a range between 10 ns and 1500 ns. ### Claim 7 (depends on 1) The method as claimed in claim 1, wherein each second laser pulse is generated spaced apart from the respective first laser pulse by the time offset in a range by between 50 ns and 1000 ns. ### Claim 8 (depends on 1) The method as claimed in claim 1, wherein each second laser pulse is generated spaced apart from the respective first laser pulse by the time offset in a range between 80 ns and 500 ns. ### Claim 9 (depends on 1) The method as claimed in claim 1, wherein the optical amplifier is configured in a form of an amplifier chain. ### Claim 10 (depends on 1) The method as claimed in claim 1, wherein the optical beam splitter comprises a dichroic mirror or a polarization mirror. ### Claim 11 (depends on 1) The method as claimed in claim 1, wherein the superimposition of the first laser pulses with the second laser pulses is performed using a dichroic mirror or a polarization mirror. ### Claim 12 A extreme ultraviolet (EUV) radiation generating device comprising: a device for generating laser pulses, the device comprising: at least one laser source for generating first laser pulses and second laser pulses, wherein the first laser pulses have at least one beam property that is different from that of the second laser pulses; an optical amplifier for amplifying the first laser pulses and the second laser pulses, wherein each respective second laser pulse passes through the optical amplifier offset in time in relation to a respective first laser pulse by a time offset; an optical beam splitter for separating the first laser pulses from the second laser pulses based on the at least one beam property; a retardation unit for the first laser pulses to pass therethrough, wherein a time duration for each respective first laser pulse to pass through a retardation section of the retardation unit corresponds to the time offset in relation to the respective second laser pulse, and wherein the second laser pulses do not pass through the retardation unit; and a superposition unit for superimposing the first laser pulses with the second laser pulses to form superimposed laser pulses; and a vacuum chamber, into which a target material is capable of being introduced in a target area and being irradiated by the superimposed laser pulses to generate EUV radiation. ### Claim 13 (depends on 12) The EUV radiation generating device as claimed in claim 12, wherein the optical amplifier is configured in a form of an amplifier chain. ### Claim 14 (depends on 13) The EUV radiation generating device as claimed in claim 13, wherein the optical amplifier comprises a plurality of CO2 amplifiers. ### Claim 15 (depends on 12) The EUV radiation generating device as claimed in claim 12, wherein the optical beam splitter comprises a dichroic mirror or a polarization mirror. ### Claim 16 (depends on 12) The EUV radiation generating device as claimed in claim 12, wherein the superposition unit comprises a dichroic mirror or a polarization mirror. ### Claim 17 (depends on 12) The EUV radiation generating device according to claim 12, further comprising a focusing unit for focusing the superimposed laser pulses in the target area to generate the EUV radiation, and a beam guiding unit for guiding the superimposed laser pulses to the focusing unit.