# US 5,350,924 A · Ion-optical imaging system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,350,924 A - Document ID: US5350924A - Status: Granted - Kind: A - Application number: 07/912,099 - Filed: 1992-07-10 - Granted: 1994-09-27 - Earliest claimed: 1991-07-10 - Assignees: IMS Ionen Mikrofabrikations Systems Gesellschaft mbH - Inventors: Gerhard Stengl; Alfred Chalupka - Web page: https://patentgrep.com/patent/US5350924A ## CPC - H01J 37/3007: {Electron or ion-optical systems} - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract A system for ion-beam imaging of a structure of a mask on a wafer has a two-lens set between the mask and the wafer which is one of the following combinations: (a) two accelerating Einzel lenses; (b) an accelerating immersion lens and a decelerating immersion lens wherein the accelerating immersion lens is the first collecting lens following the mask; (c) an accelerating immersion lens and a decelerating asymmetric Einzel lens wherein the accelerating immersion lens is the first collecting lens following the mask; (d) an accelerating asymmetric Einzel lens and a decelerating immersion lens wherein the accelerating asymmetric Einzel lens is the first collecting lens following the mask; and (e) an accelerating asymmetric Einzel lens and a decelerating asymmetric Einzel lens wherein the accelerating asymmetric Einzel lens is the first collecting lens following the mask. ## Claims ### Claim 1 An ion-optical imaging system, comprising: a mask having a structure to be imaged upon a wafer and including at least one opening; means for supporting the wafer upon which said structure is to be imaged at a distance from said mask along an optical axis; and a lens system disposed between said mask and said wafer and essentially consisting of a set of two collecting lenses including a first collecting lens following said mask along said axis in a direction of ion beam travel toward said wafer, and a second collecting lens spaced from the first collecting lens along said axis in said direction, said mask being disposed approximately in an object-side focal plane of the first collecting lens, the wafer being positioned in a vicinity of an image-side focal plane of the second collecting lens following the mask, and the set is constituted of one of the following lens-type sets: (a) two accelerating Einzel lenses; (b) an accelerating immersion lens and a decelerating immersion lens wherein the accelerating immersion lens is the first collecting lens following the mask; (c) an accelerating immersion lens and a decelerating asymmetric Einzel lens wherein the accelerating immersion lens is the first collecting lens following the mask; (d) an accelerating asymmetric Einzel lens and a decelerating immersion lens wherein the accelerating asymmetric Einzel lens is the first collecting lens following the mask; and (e) an accelerating asymmetric Einzel lens and a decelerating asymmetric Einzel lens wherein the accelerating asymmetric Einzel lens is the first collecting lens following the mask. ### Claim 2 (depends on 1) The ion-optical imaging system defined in claim 1 wherein a crossover of the first collecting lens following the mask lies in an object-side focal plane of the second collecting lens following the mask. ### Claim 3 (depends on 2) The ion-optical imaging system defined in claim 2, further comprising: an ion source disposed along said axis ahead of said mask for generating an ion beam; a mass separator formed as an ExB filter between said ion source and said mask along said axis; a condensing lens ahead of said mass separator along said axis and preferably being an Einzel lens; and an illumination lens following said mass separator along said axis and being a lens selected from the group which consists of: an immersion lens, an accelerating Einzel lens, a decelerating Einzel lens, and at least one solenoid. ### Claim 4 (depends on 3) The ion-optical imaging system defined in claim 3 wherein said set is constituted of two accelerating Einzel lenses. ### Claim 5 (depends on 3) The ion-optical imaging system defined in claim 3 wherein said set is constituted of an accelerating immersion lens and a decelerating immersion lens wherein the accelerating immersion lens is the first collecting lens following the mask. ### Claim 6 (depends on 3) The ion-optical imaging system defined in claim 3 wherein said set is constituted of an accelerating immersion lens and a decelerating asymmetric Einzel lens wherein the accelerating immersion lens is the first collecting lens following the mask. ### Claim 7 (depends on 3) The ion-optical imaging system defined in claim 3 wherein said set is constituted of an accelerating asymmetric Einzel lens and a decelerating immersion lens wherein the accelerating asymmetric Einzel lens is the first collecting lens following the mask. ### Claim 8 (depends on 3) The ion-optical imaging system defined in claim 3 wherein said set is constituted of an accelerating asymmetric Einzel lens and a decelerating asymmetric Einzel lens wherein the accelerating asymmetric Einzel lens is the first collecting lens following the mask. ### Claim 9 (depends on 3) The ion-optical imaging system defined in claim 3 wherein said illumination lens is an immersion lens. ### Claim 10 An ion-optical imaging system, comprising: a mask having a structure to be imaged upon a wafer and including at least one opening; means for supporting the wafer upon which said structure is to be imaged at a distance from said mask along an optical axis; a lens system disposed between said mask and said wafer and essentially consisting of a set of two collecting lenses including a first collecting lens following said mask along said axis in a direction of ion beam travel toward said wafer, and a second collecting lens spaced from the first collecting lens along said axis in said direction, said mask being disposed approximately in an object-side focal plane of the first collecting lens, the wafer being positioned in a vicinity of an image-side focal plane of the second collecting lens following the mask, and the set is constituted of one of the following lens-type sets: (a) two accelerating Einzel lenses; (b) an accelerating immersion lens and a decelerating immersion lens wherein the accelerating immersion lens is the first collecting lens following the mask; (c) an accelerating immersion lens and a decelerating asymmetric Einzel lens wherein the accelerating immersion lens is the first collecting lens following the mask; (d) an accelerating asymmetric Einzel lens and a decelerating immersion lens wherein the accelerating asymmetric Einzel lens is the first collecting lens following the mask; and (e) an accelerating asymmetric Einzel lens and a decelerating asymmetric Einzel lens wherein the accelerating asymmetric Einzel lens is the first collecting lens following the mask, a crossover of the first collecting lens following the mask lying in an object-side focal plane of the second collecting lens following the mask; an ion source disposed along said axis ahead of said mask for generating an ion beam; a mass separator formed as an ExB filter between said ion source and said mask along said axis; a condensing lens ahead of said mass separator along said axis and preferably being an Einzel lens; and an illumination lens following said mass separator along said axis and being an accelerating Einzel lens. ### Claim 11 An ion-optical imaging system, comprising: a mask having a structure to be imaged upon a wafer and including at least one opening; means for supporting the wafer upon which said structure is to be imaged at a distance from said mask along an optical axis; a lens system disposed between said mask and said wafer and essentially consisting of a set of two collecting lenses including a first collecting lens following said mask along said axis in a direction of ion beam travel toward said wafer, and a second collecting lens spaced from the first collecting lens along said axis in said direction, said mask being disposed approximately in an object-side focal plane of the first collecting lens the wafer being positioned in a vicinity of an image-side focal plane of the second collecting lens following the mask, and the set is constituted of one of the following lens-type sets: (a) two accelerating Einzel lenses; (b) an accelerating immersion lens and a decelerating immersion lens wherein the accelerating immersion lens is the first collecting lens following the mask; (c) an accelerating immersion lens and a decelerating asymmetric Einzel lens wherein the accelerating immersion lens is the first collecting lens following the mask; (d) an accelerating asymmetric Einzel lens and a decelerating immersion lens wherein the accelerating asymmetric Einzel lens is the first collecting lens following the mask; and (e) an accelerating asymmetric Einzel lens and a decelerating asymmetric Einzel lens wherein the accelerating asymmetric Einzel lens is the first collecting lens following the mask, a crossover of the first collecting lens following the mask lying in an object-side focal plane of the second collecting lens following the mask; an ion source disposed along said axis ahead of said mask for generating an ion beam; a mass separator formed as an ExB filter between said ion source and said mask along said axis; a condensing lens ahead of said mass separator along said axis and preferably being an Einzel lens; and an illumination lens following said mass separator along said axis and being a decelerating Einzel lens. ### Claim 12 An ion-optical imaging system, comprising: a mask having a structure to be imaged upon a wafer and including at least one opening; means for supporting the wafer upon which said structure is to be imaged at a distance from said mask along an optical axis; a lens system disposed between said mask and said wafer and essentially consisting of a set of two collecting lenses including a first collecting lens following said mask along said axis in a direction of ion beam travel toward said wafer, and a second collecting lens spaced from the first collecting lens along said axis in said direction, said mask being disposed approximately in an object-side focal plane of the first collecting lens, the wafer being positioned in a vicinity of an image-side focal plane of the second collecting lens following the mask, and the set is constituted of one of the following lens-type sets: (a) two accelerating Einzel lenses; (b) an accelerating immersion lens and a decelerating immersion lens wherein the accelerating immersion lens is the first collecting lens following the mask; (c) an accelerating immersion lens and a decelerating asymmetric Einzel lens wherein the accelerating immersion lens is the first collecting lens following the mask; (d) an accelerating asymmetric Einzel lens and a decelerating immersion lens wherein the accelerating asymmetric Einzel lens is the first collecting lens following the mask; and (e) an accelerating asymmetric Einzel lens and a decelerating asymmetric Einzel lens wherein the accelerating asymmetric Einzel lens is the first collecting lens following the mask, a crossover of the first collecting lens following the mask lying in an object-side focal plane of the second collecting lens following the mask; an ion source disposed along said axis ahead of said mask for generating an ion beam; a mass separator formed as an ExB filter between said ion source and said mask along said axis; a condensing lens ahead of said mass separator along said axis and preferably being an Einzel lens; and an illumination lens following said mass separator along said axis and being at least one solenoid.