Charged Particle Beam Transient Signal Correction
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Solution Overview
Problem
Charged particle beam apparatuses face issues with surface charging of semiconductor substrates during measurement or inspection, leading to positional deviations and image distortion when blanking electrodes are operated at high speeds, affecting measurement reliability and precision.
Innovation Solution
A charged particle beam apparatus with a control unit that includes a transient signal correction unit to manage the blanking electrode's ON and OFF states, utilizing an active discharge circuit to quickly discharge charges and a deflecting electrode control unit to correct image distortions, ensuring high-speed operation without image distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the blanking electrode is operated at high speed to turn on and off repeatedly during scanning, then the radiation time to the sample is shortened and surface charging is suppressed, but transient signals occur and cause positional deviation and image distortion
Solution Approach 1:
The patent applies preliminary action by pre-charging the blanking electrode to the blanking voltage level before the beam is actually blanked. This preparatory charging eliminates transient signals when the blanking electrode switches between ON and OFF states, preventing positional deviation and image distortion while maintaining high-speed operation capability
Solution Approach 2:
The patent uses beforehand cushioning by maintaining a capacitive energy storage system that continuously supplies charging current to the blanking electrode. This cushioning mechanism ensures that the electrode can switch states instantly without generating transient signals, thereby preventing image distortion while enabling high-speed multipoint measurement
2Measurement precision
If continuous radiation of charged particle beam is used during scanning, then measurement precision is maintained, but surface charging occurs and reliability deteriorates
Solution Approach 1:
The patent applies periodic action by repeatedly turning the charged particle beam on and off at high speed during scanning through coordinated control of the blanking electrode and beam modulation. This periodic radiation pattern reduces total exposure time to suppress surface charging while maintaining measurement precision through strategic positioning of radiation pulses at discrete points
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise measurement or inspection of minute patterns with high-speed blanking electrode operation, reducing image distortion and maintaining measurement precision by effectively managing transient signals and charge discharge.
Implementation Method 1
a blanking electrode unit that blanks the charged particle beam launched from the charged particle source unit
Implementation Method 2
utilizing an active discharge circuit to quickly discharge charges
Implementation Method 3
a deflecting electrode unit that deflects the charged particle beam launched from the charged particle source unit
Data Source
AI summary
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.