Electron source, electron gun, and charged particle beam device

An electron source comprising:

• a suppressor electrode having an opening at one end portion thereof in a direction along a central axis;
• and
• an electron emission material having a distal end protruding from the opening, wherein
• the suppressor electrode further includes a receding portion receding to a position farther from the distal end of the electron emission material than the end portion of the suppressor electrode in the direction along the central axis at a position in an outer peripheral direction than the opening, and
• the receding portion includes a tapered portion having at least two or more different angles formed with a surface perpendicular to the central axis.

An electron source comprising:

• a suppressor electrode having an opening at one end portion thereof in a direction along a central axis;
• and
• an electron emission material having a distal end protruding from the opening, wherein
• the suppressor electrode further includes a receding portion receding to a position farther from the distal end of the electron emission material than the end portion of the suppressor electrode in the direction along the central axis at a position in an outer peripheral direction than the opening,
• the receding portion includes a tapered portion forming an angle θ with a surface perpendicular to the central axis,
• at least a part of the tapered portion is disposed within a diameter L from a center of the opening, and
• the diameter L and the angle θ satisfy a relationship of 2.40×10 7×L2+3.18 ×10 4×L−4.08×10 1≤log θ≤6.68×10 7×L2−2.68×10 4×L+1.08, the diameter L being expressed in units of μm, and the angle θ being expressed in units of degrees (°).

An electron source comprising:

• a suppressor electrode having an opening at one end portion thereof in a direction along a central axis;
• and
• an electron emission material having a distal end protruding from the opening, wherein
• the suppressor electrode further includes a receding portion receding to a position farther from the distal end of the electron emission material than the end portion of the suppressor electrode in the direction along the central axis at a position in an outer peripheral direction than the opening,
• at least a part of the receding portion is disposed within a diameter L from a center of the opening,
• the electron emission material protrudes from the opening by a length T, and
• the diameter L and the length T satisfy a relationship of L=3.53T+1607, both the diameter L and the length T being expressed in units of μm.