Patent ID: 8450699

Claim:
An electron beam apparatus comprising a Schottky emission electron source, the electron source including a single-crystal tungsten metal needle as an electron emission source; a zirconium-oxygen (Zr—O) diffusion source; a heater; and a suppressor electrode, wherein the electron beam apparatus provides an extraction electrode applying an extraction voltage for extracting an electron from the Schottky emission electron source, wherein the single-crystal tungsten metal needle is shaped to have a cylindrical portion; a constricted portion arranged on and extending from the top of the cylindrical portion and having a tapered shape; and an approximately conical portion extending from the constricted portion, wherein, when the tip of the conical portion which emits electrons is assumed to be a semi-sphere having a radius of curvature of r, the radius r of curvature of the tip is more than 0.5 μm and less than 1 μm, wherein the conical portion has a cone angle of α of more than 5° and less than (8/r)°, wherein the cone angle is an opening angle of a cone constituting the conical portion, and wherein r is indicated in units of micrometers (μm)), and wherein the extraction voltage is from 2.5 kV to 3 kV when a voltage applied to the suppressor electrode is set to be −0.3 kV to −0.7 kV.