Charged particle beam device with transient signal correction during beam blanking
A charged particle apparatus including a charged particle source unit; a blanking electrode unit that blanks a charged particle beam launched from the charged particle source unit; a deflecting electrode unit that deflects the charged particle beam; an objective lens unit that converges the charged particle beam deflected by the deflecting electrode unit and radiates the charged particle beam to a surface of a sample; a secondary charged particle detection unit that detects a secondary charged particle generated from the sample; a signal processing unit that processes a signal obtained by detecting the secondary charged particle; and a control unit that corrects a transient signal when the blanking of the charged particle beam is turned off by the blanking electrode, such that an image with no distortion can be obtained even when the blanking electrode is operated to turn on and off at a high speed.
1. A charged particle beam apparatus comprising:
a charged particle source unit that launches a charged particle beam;
a blanking electrode unit that blanks the charged particle beam launched from the charged particle source unit;
a deflecting electrode unit that deflects the charged particle beam launched from the charged particle source unit and passing through the blanking electrode unit;
an objective lens unit that converges the charged particle beam deflected by the deflecting electrode unit and radiates the charged particle beam to a surface of a sample;
a secondary charged particle detection unit that detects a secondary charged particle generated from the sample irradiated with the charged particle beam;
a signal processing unit that processes a signal obtained by detecting the secondary charged particle by the secondary charged particle detection unit;
a control unit that controls the charged particle source unit, the blanking electrode unit, the deflecting electrode unit, the objective lens unit, the secondary charged particle detection unit, and the signal processing unit; and
a storage unit which stores a correction value,
wherein the control unit includes a transient signal correction unit that corrects a transient signal at the time of turning off the blanking of the charged particle beam by the blanking electrode by adding the uncorrected original deflecting signal and a blanking correction signal, based on the correction value at a timing at which the blanking signal output is switched, to the deflecting electrode,
wherein the stored correction value comprises a scanning direction on the sample, a predetermined magnification correction coefficient and a predetermined measurement magnification value,
wherein the transient signal correction unit is a discharge circuit that discharges a charge remaining in the blanking electrode when the blanking of the charged particle beam is turned off by the blanking electrode, and
wherein said discharge circuit comprises a switch electrically coupled between the blanking electrode and an output of an amplifier, said output is electrically connected in parallel with a diode electrically connected to ground, said switch being configured to receive a signal for turning off blanking from the blanking electrode unit to close a contact point and a signal for turning on blanking from the blanking electrode unit to open the contact point.
2. The charged particle beam apparatus according to claim 1 ,
wherein the transient signal correction unit is a deflecting electrode control unit that receives a signal for switching a voltage to be applied to the blanking electrode from ON to OFF and controls a signal to be applied to the deflecting electrode unit.
3. The charged particle beam apparatus according to claim 1 ,
wherein the signal processing unit processes a signal obtained by detecting the secondary charged particle by the secondary charged particle detection unit and measures dimensions of a pattern formed on the sample from a secondary charged particle image of the pattern.