Patent Number: 
Section: claims

1. A liquid metal ion gun comprising:a liquid metal member that is made of a first metal material;a liquid metal ion source that includes a reservoir and a emitter, the reservoir being made of a second metal material and holding the liquid metal member, the emitter being made of the second metal material; anda beam limiting aperture that is formed with a liquid metal member made of the first metal material placed on a base made of the second metal material, has an opening enabling an ion beam extracted from the liquid metal ion source to pass therethrough, and limits the diameter of the ion beam,wherein the beam limiting aperture has a structure that causes the liquid metal member to gather into a region located around the opening,the base has a recessed portion that is provided so as to include the opening, anda distance between the opening and an outer circumference of the recessed portion is smaller than a capillary length of the liquid metal member made of the first metal material. 2. The liquid metal ion gun according to claim 1,wherein the base has a groove structure that is provided on an inner side of the recessed portion and surrounds the opening. 3. The liquid metal ion gun according to claim 1,wherein the base includes a groove structure that is provided so as to surround the opening, andwherein an annular member is placed so as to surround the groove structure, and forms a recessed portion that includes the opening. 4. The liquid metal ion gun according to claim 1, further comprising:an annular member that is provided so as to surround the opening, and forms a recessed portion that includes the opening,wherein the annular member is made of a metal material whose wettability with the liquid metal member made of the first metal material is lower than at least wettability with the second metal material. 5. The liquid metal ion gun according to claim 4, further comprising:a groove structure that is provided on an inner side of the recessed portion so as to surround the opening. 6. The liquid metal ion gun according to claim 5,wherein at least a part of the groove structure is located in a region extending from an outer circumference of the recessed portion to a bottom surface of the recessed portion. 7. The liquid metal ion gun according to claim 1,wherein the first metal material is gallium, and the second metal material is tungsten. 8. The liquid metal ion gun according to claim 7,wherein a surface of the beam limiting aperture is wetted with molten gallium and the gallium is then solidified, so that the surface of the beam limiting aperture is formed. 9. An ion beam device comprising:a vacuum container;a liquid metal ion gun that is located inside the vacuum container and includes a liquid metal ion source and a beam limiting aperture; andan acceleration electrode,wherein the liquid metal ion source includes:a liquid metal member that is made of a first metal material;a reservoir that is made of a second metal material and holds the liquid metal member; andan emitter that is made of the second metal material,wherein the beam limiting aperture is formed with a liquid metal member made of the first metal material placed on a base made of the second metal material, has an opening enabling an ion beam extracted from the liquid metal ion source to pass therethrough, and limits the diameter of the ion beam, the base of the beam limiting aperture has a recessed portion that is provided so as to include the opening as a having a structure that causes the liquid metal member to gather into a region located around the opening, and a distance between the opening and an outer circumference of the recessed portion is smaller than a capillary length of the liquid metal member made of the first metal material, andwherein the acceleration electrode is located inside the vacuum container and accelerates the ion beam that has passed through the opening.