Patent Number: 
Section: claims

1. A hollow-beam aperture for a charged-particle-beam (CPB) microlithography apparatus, comprising: a first member, multiple second members, and a circular center member made of a CPB-absorbing material, the circular member having a radius;  the center member being supported relative to the first member by support bars extending radially from the first member to the center member;  the second members being situated between the support bars and the first member, and the second members being displaceable relative to the first member radially toward the center member;  the second members each having a distal edge, the distal edges being configured to engage the support bars whenever the second members are displaced maximally toward the center member; and  the distal edges each defining a cutout having a respective edge configured as an arc having a radius greater than the radius of the center member such that, whenever the second members are displaced maximally toward the center member, a substantially annular aperture is defined between the center member and the cutouts. 2. The hollow-beam aperture of  claim 1 , further comprising a respective spring situated relative to the first member and each of the second members, the springs being configured to urge the respective second members toward the center member, and the springs being contiguous with the first and second members and connecting the respective second members to the first member. claim 1 3. The hollow-beam aperture of  claim 1 , wherein: claim 1 the first member defines angled edges in a region between the second members; and  each second member defines angled edges that conform to and contact corresponding angled edges of the first member in a manner, whenever the second members are displaced maximally toward the center member, serving to maintain concentricity of the cutouts relative to the center portion. 4. A CPB microlithography apparatus, comprising the hollow-beam aperture of  claim 1 . claim 1 5. A hollow-beam aperture for a charged-particle-beam microlithography apparatus, comprising: a first member defining a cutout having a radial dimension;  a cylindrical beam-absorbing member having an axis and a radius relative to the axis, the radius of the beam-absorbing member being smaller than the radial dimension of the cutout;  multiple support bars supporting the beam-absorbing member relative to the first member and concentrically with the cutout such that the axis of the beam-absorbing member is perpendicular to the plane of the first member, and the beam-absorbing member extends through the cutout, thereby forming a substantially annular aperture between the beam-absorbing member and the first member; and  a second member defining a circular cutout having a radius no larger than the radial dimension of the cutout in the first member and larger than the radius of the beam-absorbing member, the second member being configured to be attached superposedly to the first member such that the cutout of the second member is coaxial with the beam-absorbing member, and the beam-absorbing member also extends through the second cutout. 6. A CPB microlithography apparatus, comprising the hollow-beam aperture of  claim 5 . claim 5 7. A hollow-beam aperture, comprising: a main body defining a circular opening having an axis and a radius;  a beam-absorbing body situated concentrically relative to the circular opening and connected to the main body by at least one support bar contiguous with the main body and the beam-absorbing body, the beam-absorbing body having a radius that is smaller than the radius of the circular opening; and  the main body defining at least one void situated relative to the circular opening and the beam-absorbing body, the void being configured so as to cause the circular opening and beam-absorbing body to define a substantially annular beam-transmitting aperture, when the hollow-beam aperture is viewed along the axis, extending through the main body and concentric with the beam-absorbing body. 8. The hollow-beam aperture of  claim 7 , wherein the circular opening has outer sides and tapered inner sides. claim 7 9. The hollow-beam aperture of  claim 8 , wherein the beam-absorbing body is conical relative to the axis. claim 8 10. The hollow-beam aperture of  claim 7 , wherein the beam-absorbing body is defined by a portion of the main body that is relatively thick in a beam-transmission direction, and the substantially annular beam-transmitting aperture is defined by a portion of the main body that is relatively thin in the beam-transmission direction. claim 7 11. The hollow-beam aperture of  claim 10 , wherein the circular opening is machined by EDM using the beam-absorbing body as an EDM electrode. claim 10 12. The hollow-beam aperture of  claim 7 , wherein the circular opening has a truncated conical profile as viewed along a direction perpendicular to the axis of the beam-absorbing body, the circular opening extending into the main body from a first surface of the main body. claim 7 13. The hollow-beam aperture of  claim 12 , wherein: claim 12 the main body defines at least two voids each having a respective axis that is parallel to the axis of the beam-absorbing body, the voids extending into the main body from a second surface of the main body opposite the first surface;  the voids are arranged such that their respective axes are spaced equally from one another about the axis of the beam-absorbing body in a rotationally symmetric manner; and  each of the voids intersects, within the main body, a respective portion of the circular opening. 14. The hollow-beam aperture of  claim 13 , wherein each of the voids has a truncated conical profile as viewed along a direction perpendicular to the axis of the beam-absorbing body. claim 13 15. A CPB microlithography apparatus, comprising the hollow-beam aperture of  claim 7 . claim 7 16. A method for manufacturing a hollow-beam aperture for use in a charged-particle-beam (CPB) microlithography apparatus, comprising: (a) providing a main body made of a CPB-absorbing material;  (b) on a first surface of the main body, machining a circular opening having an axis and a radius;  (c) on a second surface of the main body opposite the first surface, machining the main body to define a beam-absorbing body concentrically relative to the circular opening, the beam-absorbing body having a radius smaller than the radius of the circular opening, the circular opening and the beam-absorbing body each having a relatively thick dimension in a beam-transmission direction and being separated from each other by a portion of the main body that is relatively thin in the beam-transmission direction; and  (d) machining the main body to define at least one void situated relative to the circular opening and the beam-absorbing body, the void being configured so as to cause the circular opening and the beam-absorbing body to define a beam-transmitting aperture that is concentric with the beam-absorbing body and substantially annular in profile when viewed along the axis, the beam-transmitting aperture extending through the portion of the main body, between the beam-absorbing body and the circular opening, that is relatively thin in the beam-transmission direction. 17. The method of  claim 16 , wherein step (b) comprises machining the circular opening to have a truncated conical profile as viewed along a direction perpendicular to the axis, and to extend into the main body from the first surface. claim 16 18. The method of  claim 16 , wherein step (b) comprises machining an annular groove in the first surface. claim 16 19. A microelectronic-device fabrication process, comprising the steps: (a) preparing a wafer;  (b) processing the wafer; and  (c) assembling devices formed on the wafer during steps (a) and (b), wherein step (b) comprises the steps of (i) applying a resist to the wafer; (ii) exposing the resist; and (iii) developing the resist; and step (ii) comprises providing a CPB microlithography apparatus as recited in  claim 4 ; and using the CPB microlithography apparatus to expose the resist with the pattern defined on the reticle.  claim 4 20. A microelectronic-device fabrication process, comprising the steps: (a) preparing a wafer;  (b) processing the wafer; and  (c) assembling devices formed on the wafer during steps (a) and (b), wherein step (b) comprises the steps of (i) applying a resist to the wafer; (ii) exposing the resist; and (iii) developing the resist; and step (ii) comprises providing a CPB microlithography apparatus as recited in  claim 6 ; and using the CPB microlithography apparatus to expose the resist with the pattern defined on the reticle.  claim 6 21. A microelectronic-device fabrication process, comprising the steps: (a) preparing a wafer;  (b) processing the wafer; and  (c) assembling devices formed on the wafer during steps (a) and (b), wherein step (b) comprises the steps of (i) applying a resist to the wafer; (ii) exposing the resist; and (iii) developing the resist; and step (ii) comprises providing a CPB microlithography apparatus as recited in  claim 15 ; and using the CPB microlithography apparatus to expose the resist with the pattern defined on the reticle.  claim 15 22. A method for manufacturing a hollow-beam aperture for use in a charged-particle-beam (CPB) microlithography apparatus, comprising: (a) providing a main body made of a CPB-absorbing material;  (b) on a first surface of the main body, machining an annular opening having an axis and a radius, and defining a beam-absorbing body having a radius smaller than the radius of the annular opening, the annular opening and the beam-absorbing body each having a relatively thick dimension in a beam-transmission direction and being separated from each other by a portion of the main body that is relatively thin in the beam-transmission direction; and  (c) machining the main body to define at least one void situated relative to the annular opening and the beam-absorbing body, the void being configured so as to cause the annular opening and the beam-absorbing body to define a beam-transmitting aperture that is concentric with the beam-absorbing body and substantially annular in profile when viewed along the axis, the beam-transmitting aperture extending through the portion of the main body, between the beam-absorbing body and the annular opening, that is relatively thin in the beam-transmission direction. 23. A hollow-beam aperture for a charged-particle-beam (CPB) microlithography apparatus, comprising: a charged-particle-stopping member defining a cutout extending along an axis through a thickness dimension of the charged-particle-stopping member; and  a support member defining multiple openings, the support member being situated relative to the cutout in the charged-particle-stopping member so as to collectively define a substantially annular aperture coaxial with the axis. 24. The hollow-beam aperture of  claim 23 , further comprising a reinforcing member defining an opening coaxial with the axis. claim 23 25. The hollow-beam aperture of  claim 24 , wherein the charged-particle-stopping member, the support member, and the reinforcing member are integrated as a unitary construct. claim 24 26. A method for manufacturing a hollow-beam aperture for use in a charged-particle-beam (CPB) microlithography apparatus, comprising: (a) providing a main body having first and second main surfaces and a thickness dimension extending along an axis between the first and second main surfaces;  (b) defining multiple second openings extending from the first main surface into the thickness dimension, the second openings being situated radially symmetrically relative to the axis;  (c) defining a third opening extending from the second main surface into the thickness dimension, the third opening being situated coaxially with the axis and intersecting the second openings in the thickness dimension so as to define a substantially annular aperture as viewed along the axis. 27. The method of  claim 26 , further comprising the steps: claim 26 before, step (b), defining a first opening extending along the axis from the second main surface into the thickness dimension, the first opening having a bottom surface; and  step (b) comprises defining the multiple second openings extending from the bottom surface further into the thickness dimension from the bottom surface.