# US 10,319,557 B2 · Ion generator and method for using the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,319,557 B2 - Document ID: US10319557B2 - Status: Granted - Kind: B2 - Application number: 15/692,745 - Filed: 2017-08-31 - Published: 2019-02-28 - Granted: 2019-06-11 - Earliest claimed: 2017-08-31 - Assignees: Taiwan Semiconductor Manufacturing Company, Ltd. - Applicants: Taiwan Semiconductor Manufacturing Co., Ltd. - Inventors: Tai-Kun Kao; Tsung-Min Lin; Jen-Chung Chiu; Ren-Dou Lee - Web page: https://patentgrep.com/patent/US10319557B2 ## CPC - H01J 37/08: Ion sources; Ion guns - H01J 37/3171: {for ion implantation} - H01J 2237/061: Construction - H01J 2237/082: Electron beam - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract Ion generators for ion implanters are provided. The ion generator for an ion implanter includes an ion source arc chamber including an arc chamber housing and a thermal electron emitter coupled to the arc chamber housing. In addition, the thermal electron emitter includes a filament and a cathode, and the cathode has a solid top portion made of a work function modified conductive material including tungsten (W) and a work function modification metal. ## Claims ### Claim 1 An ion generator for an ion implanter, comprising: an ion source arc chamber comprising an arc chamber housing; and a thermal electron emitter coupled to the arc chamber housing, wherein the thermal electron emitter comprises a filament and a cathode, wherein the cathode has a solid top portion and a hollow bottom portion connected to the solid top portion, and the solid top portion is made of a work function modified conductive material comprising tungsten (W) and a work function modification metal, and the filament is also made of the work function modified conductive material, and a ratio of a thickness of the solid top portion to a thickness of the hollow bottom portion is in a range from about 1:13.4 to about 1:13.9. ### Claim 2 (depends on 1) The ion generator for an ion implanter as claimed in claim 1, wherein the work function modification metal comprises lanthanum (La), Cerium (Ce), or thorium (Th). ### Claim 3 (depends on 1) The ion generator for an ion implanter as claimed in claim 1, wherein the work function modified conductive material is an alloy of lanthanum and tungsten. ### Claim 4 (depends on 1) The ion generator for an ion implanter as claimed in claim 1, wherein the solid top portion and the hollow bottom portion are made of different materials. ### Claim 5 (depends on 4) The ion generator for an ion implanter as claimed in claim 4, wherein the filament is disposed in a hollow region of the hollow bottom portion of the cathode and is not in physical contact with the cathode. ### Claim 6 (depends on 1) The ion generator for an ion implanter as claimed in claim 1, wherein a concentration of the work function modification metal in the work function modified conductive material is in a range from about 1.5 vol % to about 5 vol %. ### Claim 7 (depends on 1) The ion generator for an ion implanter as claimed in claim 1, wherein the solid top portion of the cathode has a rectangular cross-sectional area in a range from about 61.5 mm2 to about 63.9 mm2. ### Claim 8 (depends on 1) The ion generator for an ion implanter as claimed in claim 1, wherein the thickness of the solid top portion is in a range from about 2 mm to about 4 mm. ### Claim 9 A method for generating ions in an ion generator, comprising: introducing a reactant gas into an ion source arc chamber; heating a filament to emit first electrons from the filament, and the first electrons bombard a cathode to emit second electrons, wherein the cathode is coupled to an arc chamber housing of the ion source arc chamber; and generating plasma by collision between the reactant gas and the second electrons, wherein the cathode comprises a solid top portion and a hollow bottom portion connected to the solid top portion, and the solid top portion is made of a first material comprising tungsten and lanthanum, and a ratio of a thickness of the solid top portion of the cathode to a thickness of the hollow bottom portion of the cathode is in a range from about 1:13.4 to about 1:13.9, and the filament is made of a second material comprising tungsten and lanthanum. ### Claim 10 An ion generator for an ion implanter, comprising: an arc chamber housing; a cathode coupled to a first side of the arc chamber housing, wherein the cathode comprises a solid top portion and a hollow bottom portion; and a filament fixed in a hollow region surrounded by a cathode wall of the hollow bottom portion of the cathode, wherein the solid top portion of the cathode is made of a material comprising tungsten and lanthanum, and a ratio of a thickness of the solid top portion of the cathode to a thickness of the hollow bottom portion of the cathode is in a range from about 1:13.4 to about 1:13.9. ### Claim 11 (depends on 10) The ion generator for an ion implanter as claimed in claim 10, wherein the solid top portion of the cathode has a rectangular cross-sectional area in a range from about 61.5 mm2 to about 63.9 mm2. ### Claim 12 (depends on 10) The ion generator for an ion implanter as claimed in claim 10, further comprising: a repeller coupled to a second side of the arc chamber housing opposite to the first side of the arc chamber housing; and a gas source coupled to a third side of the arc chamber housing. ### Claim 13 (depends on 10) The ion generator for an ion implanter as claimed in claim 10, wherein the solid top portion of the cathode has a thickness measured along a direction vertical to a top surface of the solid top portion of the cathode in a range from about 2 mm to about 4 mm. ### Claim 14 (depends on 10) The ion generator for an ion implanter as claimed in claim 10, wherein a concentration of lanthanum in the work function modified conductive material is in a range from about 1.5 vol % to about 5 vol %. ### Claim 15 (depends on 10) The ion generator for an ion implanter as claimed in claim 10, wherein the solid top portion and the hollow bottom portion are made of different materials. ### Claim 16 (depends on 10) The ion generator for an ion implanter as claimed in claim 10, wherein the filament is made of a work function modified conductive material comprising tungsten and lanthanum. ### Claim 17 (depends on 9) The method for generating ions in an ion generator as claimed in claim 9, further comprising: forming lanthanum ions from the solid top portion of the cathode in the ion source arc chamber; and extracting the lanthanum ions from the ion source arc chamber. ### Claim 18 (depends on 9) The method for generating ions in an ion generator as claimed in claim 9, wherein a difference of a molecular weight of the reactant gas and a molecular weight of the lanthanum is greater than 30. ### Claim 19 (depends on 9) The method for generating ions in an ion generator as claimed in claim 9, wherein a concentration of lanthanum in the work function modified conductive material is in a range from about 1.5 vol % to about 5 vol %. ### Claim 20 (depends on 9) The method for generating ions in an ion generator as claimed in claim 9, wherein a concentration of lanthanum in the first material is different from a concentration of lanthanum in the second material.