Charged particle beam system and chamber of charged particle beam system

A charged particle beam system comprising:

• an invar alloy chamber having a space to accommodate a specimen and a first opening to communicate with the space in an upper surface;
• a table placed, immediately below the first opening, on a bottom surface of the chamber, the table being movable in at least one direction;
• a laser interferometer set in the chamber, the laser interferometer comprising
• a laser oscillator placed along the one moving direction of the table,
• a movable mirror placed on that side surface of the table, which opposes the laser oscillator,
• a beam splitter placed on a line connecting the laser oscillator and the movable mirror, and
• a fixed mirror perpendicular to the line connecting the laser oscillator and the movable mirror and fixed, immediately above the beam splitter, on the upper surface of the chamber;
• an optical lens barrel having a second opening communicating with the first opening of the chamber, and coupled with the chamber so as to match the first opening and the second opening;
• and
• a beam gun set on an inner upper surface of the optical lens barrel to irradiate the specimen placed on the table set on the bottom surface of the chamber with a charged particle beam through the first opening and the second opening.

A chamber of a charged particle beam system, comprising:

• a housing having a space to accommodate a specimen and an opening to communicate with the space in an upper surface;
• a table placed, immediately below the first opening, on a bottom surface of the housing, the table being movable in at least one direction;
• and
• a laser interferometer set in the housing, the laser interferometer comprising
• a laser oscillator placed along the one moving direction of the table,
• a movable mirror placed on that side surface of the table, which opposes the laser oscillator,
• a beam splitter placed on a line connecting the laser oscillator and the movable mirror, and
• a fixed mirror perpendicular to the line connecting the laser oscillator and the movable mirror and fixed, immediately above the beam splitter, on the upper surface of the housing,
• wherein at least an upper wall portion from the opening to a fixed portion of the fixed mirror of the housing is made of an invar alloy.

A charged particle beam system comprising:

• a chamber having an upper wall with an opening, at least a part of the upper wall of the chamber close to the upper opening being made of an invar or an invar alloy;
• a table supporting a specimen below the upper opening in the chamber, the table being at least movable to a first direction;
• a beam gun irradiating a charged particle beam;
• an optical lens system which directs the charged particle beam through the upper opening to the specimen on the table;
• and
• a laser interferometer associated with the table in the chamber,
• wherein the laser interferometer comprises:
• a laser source irradiating a laser beam to the first direction;
• a first mirror fixed on a side surface of the table, opposing to the laser source and being movable with the table;
• a second mirror fixed to the part of the upper wall of the chamber;
• a beam splitter which directs the laser beam from the laser source to both of the first mirror and the second mirror;
• and
• a detector which detects reflected laser beams from both of the first mirror and the second mirror.