# US 2016/0366756 A1 · Method for euv power improvement with fuel droplet trajectory stabilization > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2016/0366756 A1 - Document ID: US20160366756A1 - Status: Published application - Kind: A1 - Application number: 14/736,322 - Filed: 2015-06-11 - Published: 2016-12-15 - Earliest claimed: 2015-06-11 - Assignees: Taiwan Semiconductor Manufacturing Company, Ltd. - Applicants: Taiwan Semiconductor Manufacturing Co., Ltd. - Inventors: Tsiao-Chen Wu; Jaw-Jung Shin - Web page: https://patentgrep.com/patent/US20160366756A1 ## CPC - H05G 2/002: {Supply of the plasma generating material} - G03F 7/70033: {by plasma extreme ultraviolet [EUV] sources} - H05G 2/007: {involving electric or magnetic fields in the process of plasma generation} - H05G 2/0082: {the energy-carrying beam being a laser beam} - 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) - G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G) ## Abstract The present disclosure relates to an extreme ultraviolet (EUV) radiation source that generates charged tin droplets having a trajectory controlled by an electromagnetic field, and an associated method. In some embodiments, the EUV radiation source has a laser that generates a laser beam. A charged fuel droplet generator provides a plurality of charged fuel droplets having a net electrical charge to an EUV source vessel. An electromagnetic field generator generates an electric field and/or a magnetic field. The net electrical charge of the charged fuel droplets causes the electric or magnetic field to generate a force on the charged fuel droplets that controls a trajectory of the charged fuel droplets to intersect the laser beam. By using the electric or magnetic field to control a trajectory of the charged fuel droplets, the EUV system is able to avoid focus issues between the laser beam and the charged fuel droplets. ## Claims ### Claim 1 An extreme ultraviolet (EUV) radiation source, comprising: a charged fuel droplet generator configured to provide a plurality of charged fuel droplets having a net positive or negative electrical charge to an EUV source vessel; a laser configured to generate a laser beam having a sufficient energy to ignite a plasma from the charged fuel droplets, wherein the plasma emits extreme ultraviolet radiation; and an electromagnetic field generator configured to generate an electric field or a magnetic field that stabilizes a trajectory of the charged fuel droplets within the EUV source vessel, prior to ignition of the charged fuel droplets, along a path intersecting the laser beam. ### Claim 2 (depends on 1) The EUV radiation source of claim 1, further comprising: a fuel droplet generator configured to provide a plurality of un-charged fuel droplets to an EUV source vessel; and an ion species injector configured to generate a beam of charged ion species that is incident upon the plurality of un-charged fuel droplets, wherein upon hitting the plurality of un-charged fuel droplets, the charged ion species attach to the plurality of un-charged fuel droplets to generate the plurality of charged fuel droplets. ### Claim 3 (depends on 2) The EUV radiation source of claim 2, wherein the ion species injector comprises an electron gun configured to generate an electron beam, wherein the electron gun comprises: a hot cathode configured to generate electrons via thermionic emission; a collimator lens configured to form a beam of electrons; an aperture lens and a condenser lens configured to focus the beam of electrons; and a downstream blanker configured to remove electrons that are outside of the beam of electrons to form the electron beam. ### Claim 4 (depends on 2) The EUV radiation source of claim 2, wherein the beam of charged ion species has a lower energy than the laser beam, and the beam of charged ion species is configured to deform the plurality of charged fuel droplets to increase a size of the charged fuel droplets as viewed from the laser. ### Claim 5 (depends on 2) The EUV radiation source of claim 2, further comprising: a control element configured to selective adjust one or more characteristics of the ion species injector; and a measurement unit configured to measure a position of the un-charged fuel droplets and to provide a control signal to the control element that causes the control element to adjust a shape or a size of the beam of charged ion species. ### Claim 6 (canceled) ### Claim 7 (depends on 1) The EUV radiation source of claim 1, further comprising: a pre-pulse laser configured to generate a pre-pulse laser beam, having a lower energy than the laser beam, which is configured to deform the plurality of charged fuel droplets, wherein the pre-pulse laser is arranged so that the pre-pulse laser beam hits the plurality of charged fuel droplets prior to the laser beam hitting the plurality of charged fuel droplets. ### Claim at position 8 8-9. (canceled) ### Claim 10 (depends on 1) The EUV radiation source of claim 1, further comprising: a vapor shield source configured to provide a gas into the EUV source vessel that mitigates accumulation of residue from the charged fuel droplets, which have not been completely vaporized when struck by the laser beam, on a collector mirror. ### Claim 11 (depends on 1) The EUV radiation source of claim 1, wherein the electromagnetic field generator comprises a conductive coil wrapped around the EUV source vessel and configured to control the trajectory of the plurality of charged fuel droplets by way of the electric field or the magnetic field. ### Claim 12 (depends on 1) The EUV radiation source of claim 1, wherein the plurality of charged fuel droplets comprise tin. ### Claim 13 An EUV radiation source, comprising: a tin droplet generator configured to generate a plurality of un-charged tin droplets; an electron gun configured to generate an electron beam of electrons that is incident upon the plurality of un-charged tin droplets, wherein upon hitting the plurality of un-charged tin droplets electrons from the electron beam attach to the plurality of un-charged tin droplets to generate a plurality of charged tin droplets having a net negative electrical charge, wherein the electron gun comprises: a hot cathode configured to generate electrons via thermionic emission; a collimator lens configured to form a beam of electrons; an aperture lens and a condenser lens configured to focus the beam of electrons; and a downstream blanker configured to remove electrons that are outside of the beam of electrons to form the electron beam; a carbon dioxide (CO2) laser configured to generate a laser beam having a sufficient energy to ignite a plasma from the plurality of charged tin droplets within an EUV source vessel, wherein the plasma emits extreme ultraviolet radiation; and an electromagnetic field generator configured to generate an electric field or a magnetic field that controls a trajectory of the plurality of charged tin droplets. ### Claim 14 (depends on 13) The EUV radiation source of claim 13, further comprising: a collector mirror having a concave curvature configured to focus the extreme ultraviolet radiation to a downstream optical system comprising a plurality of mirrors configured to convey the extreme ultraviolet radiation to a semiconductor workpiece; and a pre-pulse laser configured to generate a pre-pulse laser beam, having a lower energy than the laser beam, which is configured to deform the plurality of charged tin droplets, wherein the pre-pulse laser is arranged so that the pre-pulse laser beam hits the plurality of charged tin droplets prior to the laser beam hitting the plurality of charged tin droplets. ### Claim 15 (depends on 14) The EUV radiation source of claim 14, further comprising: a vapor shield source configured to provide a gas into the EUV source vessel that mitigates accumulation of residue from the charged tin droplets, which have not been completely vaporized when struck by the laser beam, on the collector mirror. ### Claim 16 (depends on 13) The EUV radiation source of claim 13, further comprising: a control element configured to selective adjust one or more characteristics of the electron gun; and a measurement unit configured to measure a position of the un-charged tin droplets and to provide a control signal to the control element that causes the control element to adjust the one or more characteristics of the electron gun. ### Claim 17 (depends on 13) The EUV radiation source of claim 13, wherein the electromagnetic field generator comprises a conductive coil wrapped around the EUV source vessel and configured to control the trajectory of the plurality of charged tin droplets. ### Claim 18 (depends on 13) The EUV radiation source of claim 13, wherein the electron beam has a lower energy than the laser beam, and the electron beam is configured to deform the plurality of charged tin droplets. ### Claim 19 A method of generating extreme ultraviolet (EUV) radiation, comprising: generating a plurality of charged fuel droplets having a net positive or negative electrical charge; generating an electric field or a magnetic field configured to stabilize a trajectory of the plurality of charged fuel droplets; focusing a laser beam on the plurality of charged fuel droplets to generate extreme ultraviolet (EUV) radiation; and wherein the electric field or the magnetic field stabilizes the trajectory of the plurality of charged fuel droplets, prior to ignition of the charged fuel droplets, along a path intersecting the laser beam. ### Claim 20 (depends on 19) The method of claim 19, wherein generating the plurality of charged fuel droplets comprises: generating a plurality of un-charged fuel droplets; and hitting the plurality of un-charged fuel droplets with a beam of ion species to form the plurality of charged fuel droplets. ### Claim 21 (depends on 2) The EUV radiation source of claim 2, wherein the un-charged fuel droplets have a diameter of less than or equal to approximately 20 microns so as to provide for a charge-to-mass ratio that improves controllability of the charged fuel droplets by the electric field or the magnetic field. ### Claim 22 (depends on 14) The EUV radiation source of claim 14, wherein the electron gun is arranged between the pre-pulse laser and the tin droplet generator. ### Claim 23 (depends on 19) The method of claim 19, further comprising: operating a conductive coil wrapped around an EUV source vessel to generate the electric field or the magnetic field configured to control the trajectory of the plurality of charged fuel droplets prior to ignition of the charged fuel droplets.