Charged particle beam apparatus
AssigneeHitachi, Ltd.
InventorsYoshimi Kawanami, Tsuyoshi Ohnishi, Tohru Ishitani, Tooru Habu, Masahiro Yamaoka
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Abstract
A charged particle beam apparatus is provided with an aperture device which includes a plurality of slit plates. Each of the slit plates includes a plurality of slits having different widths. The slit plates are superimposed in a direction of the axis of a charged particle beam so that the corresponding slits in the slit plates overlap to define an aperture which controls a beam current.
Claims31
A charged particle beam apparatus for irradiating a specimen with a beam of charged particles, comprising:
- a charged particle source;
- an optical system for focusing and deflecting charged particles emitted from said charged particle source to irradiate any given position on the specimen with a focused charged particle beam;
- a specimen stage for holding the specimen thereon and providing a small movement to the specimen;
- a plurality of slit plates superimposed in a direction of the axis of said beam, each of said plurality of slit plates including a plurality of slits, each slit having substantially parallel opposed long sides extending equidistant from a virtual trajectory direction line, and the slits of each plate having predetermined different widths between the opposed long sides and the same width as corresponding slits of the other of said slit plates;
- and
- slit plate moving means for moving said slit plates along the virtual trajectory direction lines of their slits with the the virtual trajectory direction lines of the slits of said slit plates intersecting each other and the beam, and for stopping the moving of said slit plates so that corresponding ones of the slits in said slit plates overlap to form an aperture that controls the beam.
A method of controlling a beam current of a beam of charged particles emitted from a charged particle source, comprising the steps of:
- superimposing, a plurality of slit plates, each including a plurality of slits arranged in a virtual trajectory direction of that slit plate, and each slit having substantially parallel opposed long sides extending equidistant from a virtual trajectory direction line and the slits of each plate having predetermined different widths between the opposed long sides and the same width as corresponding slits of the other of said slit plates;
- moving each of said slit plates in its virtual trajectory direction while keeping the virtual trajectory direction lines intersecting each other and said beam;
- and
- stopping the moving of said slit plates when corresponding ones of the slits in said slit plates overlap to form an aperture thereby controlling said beam current.
Dependencies are inferred from the claim text.