Charged particle beam device and specimen observation method

A specimen observation method using a charged particle beam device including a charged particle optical system, a detection system, and a computer,

• the charged particle optical system including a charged particle source, one or more lenses configured to focus a charged particle beam from the charged particle source on a specimen, and a deflector configured to deflect the charged particle beam to scan the specimen,
• the detection system including a detector configured to detect signal charged particles or an electromagnetic wave emitted by irradiating the specimen with the charged particle beam, a phase-sensitive detector configured to input the detection signal from the detector and the reference signal for the synchronous detection and a phase adjuster configured to adjust a phase of the reference signal input to the phase-sensitive detector and
• the specimen observation method comprising:
• allowing the computer to set at least one of the charged particle optical system or the detection system so as to modulate an intensity of the signal charged particles or the electromagnetic wave detected by the detector at a predetermined frequency;
• allowing the charged particle optical system to scan the specimen two-dimensionally by repeatedly scanning the specimen with the charged particle beam in a first direction while shifting the position in a direction perpendicular to the first direction;
• and
• allowing the computer to generate an image or a signal profile based on a detection signal output from the detector when the detector detects signal charged particles or an electromagnetic wave emitted by irradiating an irradiation position corresponding to one pixel with the charged particle beam;
• wherein the image or the signal profile is generated by associating an irradiation position of the charged particle beam with a DC component of a signal, which is acquired through synchronous detection of a detection signal from the detector at the irradiation position with a reference signal having the predetermined frequency;
• wherein the computer sets a period where the irradiation position corresponding to one pixel is irradiated with the charged particle beam to be a positive integer multiple of a modulation period of the intensity of the signal charged particles or the electromagnetic wave detected by the detector and adjusts a phase adjustment amount of the reference signal by the phase adjuster to be a phase difference of zero between the detection signal from the detector and the reference signal input to the phase-sensitive detector, and
• the computer sets a period of time from start of scanning in the first direction at one position to start of scanning in the first direction at a next position to be a positive integer multiple of a modulation period of the intensity of the signal charged particles or the electromagnetic wave detected by the detector, or at a timing of start of scanning in the first direction, the computer resets the modulation of the signal charged particles or the electromagnetic wave detected by the detector per scanning in the first direction such that the modulation of the intensity of the signal charged particles or the electromagnetic wave detected by the detector has the same phase.

A charged particle beam device comprising:

• a charged particle optical system including a charged particle source, one or more lenses configured to focus a charged particle beam from the charged particle source on a specimen, and a deflector configured to deflect the charged particle beam to scan the specimen;
• a detection system including a detector configured to detect signal charged particles or an electromagnetic wave emitted by irradiating the specimen with the charged particle beam;
• a computer configured to control the charged particle optical system to scan the specimen two-dimensionally by repeatedly scanning the specimen with the charged particle beam in a first direction while shifting the position in a direction perpendicular to the first direction and to generate an image or a signal profile based on a detection signal output from the detector when the detector detects signal charged particles or an electromagnetic wave emitted by irradiating an irradiation position corresponding to one pixel with the charged particle beam,
• wherein the computer controls at least one of the charged particle optical system or the detection system so as to modulate an intensity of the signal charged particles or the electromagnetic wave detected by the detector at a predetermined frequency, and generates the image or the signal profile by associating an irradiation position of the charged particle beam with a DC component of a signal, which is acquired through synchronous detection of a detection signal from the detector at the irradiation position with a reference signal having the predetermined frequency,
• wherein the computer sets a period where the irradiation position corresponding to one pixel is irradiated with the charged particle beam to be a positive integer multiple of a modulation period of the intensity of the signal charged particles or the electromagnetic wave detected by the detector,
• the computer sets a period of time from start of scanning in the first direction at one position to start of scanning in the first direction at a next position to be a positive integer multiple of a modulation period of the intensity of the signal charged particles or the electromagnetic wave detected by the detector, or at a timing of start of scanning in the first direction, the computer resets the modulation of the signal charged particles or the electromagnetic wave detected by the detector per scanning in the first direction such that the modulation of the intensity of the signal charged particles or the electromagnetic wave detected by the detector has the same phase,
• the computer converts the detection signal from the detector into a digital signal and takes in the digital signal based on a sampling signal, sets a frequency of the sampling signal to be two times or more of a modulation frequency of the intensity of the signal charged particles or the electromagnetic wave detected by the detector, and executes a control such that the modulation of the intensity of the signal charged particles and the electromagnetic wave detected by the detector and the sampling signal are synchronized with a predetermined phase difference, and
• the computer adjusts a phase adjustment amount of the reference signal to be a phase difference of zero between the detection signal from the detector and the reference signal for the synchronous detection.