Multipole Lens Beam Switching for Fast Pre-Charge and Imaging
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Solution Overview
Problem
Current pre-charging techniques in charged particle beam microscopes, such as SEM and TEM, are time-consuming and reduce system throughput due to the need for separate electron sources and slow switching times between pre-charging and imaging, especially when detecting defects with high leakage rates.
Innovation Solution
The use of multipole lenses above and below the aperture to adjust the beam current and spot size/shape of the charged-particle beam, allowing for rapid and precise control of beam conditions without altering the condenser lens settings, enabling efficient pre-charging and imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If flooding technique is used for pre-charging, then a large amount of electrons can be applied to charge the wafer surface, but the switching time between pre-charging and imaging increases significantly
Solution Approach 1:
The patent combines the pre-charging function and imaging function into a single primary electron beam system, eliminating the need for a separate flooding gun and reducing switching time between pre-charging and imaging operations
2Loss of time
If pre-scanning technique is used with small beam current, then switching time is reduced, but adequate charging cannot be achieved for defects with high leakage rate
Solution Approach 1:
The patent implements dynamic adjustment of beam current during pre-scanning, allowing the system to increase beam current temporarily to achieve adequate charging for high leakage rate defects, then reduce it for normal imaging operations
Solution Approach 2:
The patent changes the beam current parameter during pre-scanning to optimize both charging efficiency and switching speed, adjusting the current level based on the specific inspection requirements and defect characteristics
3Quantity of substance
If higher beam current is applied during pre-scanning, then adequate charging is achieved for high leakage rate defects, but beam condition control becomes less precise
Solution Approach 1:
The patent segments the beam control function into separate components, allowing independent optimization of beam current adjustment and beam condition control through dedicated control circuits for each function
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
This approach significantly reduces switching times between pre-scanning and imaging, enhancing the throughput of the electron-beam tool by allowing for higher beam currents and precise spot adjustments, improving the detection of defects with high leakage rates.
Implementation Method 1
one or more first multipole lenses displaced above an aperture, the one or more first multipole lenses being configured to adjust a beam current of a charged-particle beam passing through the aperture
Implementation Method 2
one or more second multipole lenses displaced below the aperture, the one or more second multipole lenses being configured to adjust at least one of a spot size and a spot shape of the beam
Data Source
AI summary
Apparatus and methods for adjusting beam condition of charged particles are disclosed. According to certain embodiments, the apparatus includes one or more first multipole lenses displaced above an aperture, the one or more first multipole lenses being configured to adjust a beam current of a charged-particle beam passing through the aperture. The apparatus also includes one or more second multipole lenses displaced below the aperture, the one or more second multipole lenses being configured to adjust at least one of a spot size and a spot shape of the beam.