Condenser Lens Mode Switching for High-Current Voltage-Contrast Inspection
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Solution Overview
Problem
Existing charged particle beam inspection systems face challenges in achieving sufficient probe current for voltage-contrast inspection in complex structures like VNAND or 3D-NAND, which can lead to inadequate or inefficient defect detection.
Innovation Solution
A charged particle beam apparatus with a condenser lens configuration that can operate in two modes: a non-crossover mode for normal operation and a crossover mode to form a beam crossover, allowing for increased probe current while maintaining high imaging resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple electron beams are used to increase throughput, then productivity is improved, but probe current per beamlet becomes insufficient for voltage-contrast inspection
Solution Approach 1:
The patent divides the electron beam into multiple beamlets arranged in a grid pattern, where each beamlet can be independently controlled. This segmentation allows the system to maintain high total throughput while concentrating sufficient probe current in each individual beamlet for effective voltage-contrast inspection of 3D-NAND structures.
Solution Approach 2:
The patent transitions from single-beam inspection to a multi-beam array configuration, adding spatial dimensionality to the beam structure. By arranging beamlets in a two-dimensional grid and selectively activating them, the system achieves both high throughput (through parallel beams) and sufficient probe current per beamlet (through selective activation and current concentration).
2Productivity
If multiple electron beams are used to increase throughput, then productivity is improved, but image quality deteriorates due to increased Coulomb interaction
Solution Approach 1:
By segmenting the electron beam into spatially separated beamlets, the patent reduces Coulomb interaction between electrons from different beams. Each beamlet operates with sufficient current for voltage-contrast inspection while maintaining image quality, as the segmented structure minimizes electron-electron interactions compared to a single high-current beam.
Solution Approach 2:
The patent applies local quality by optimizing each beamlet's current and positioning individually rather than uniformly distributing current across all beams. This allows each beamlet to have the precise current characteristics needed for high-quality voltage-contrast imaging while maintaining overall high throughput through the multi-beam configuration.
3Quantity of substance
If a high intensity electron emission source is used to generate large current beams, then probe current is improved, but source stability and efficiency worsen
Solution Approach 1:
The patent segments the total required probe current into multiple smaller beamlets, each carrying a manageable current level that maintains source stability. Instead of requiring a single high-intensity source that would be unstable, the system uses a moderate-intensity source to generate multiple beamlets whose currents collectively provide sufficient probe current for voltage-contrast inspection.
Solution Approach 2:
The patent transitions from a single high-current beam requiring an intense (and unstable) source to a multi-dimensional beamlet array where each element receives moderate current. This dimensional transformation allows the use of a stable, moderate-intensity electron source while achieving the necessary total probe current through the distributed beamlet structure.
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
The apparatus enhances the probe current in the crossover mode, enabling efficient voltage-contrast inspection with improved defect detection capabilities and increased throughput, while maintaining high imaging resolution.
Implementation Method 1
a condenser lens configuration configured to condense the primary charged-particle beam based on a selected mode of operation of the apparatus
Implementation Method 2
a charged-particle source configured to emit charged particles
Data Source
AI summary
Systems and methods of inspecting a sample using a charged-particle beam apparatus with enhanced probe current and high current density of the primary charged-particle beam are disclosed. The apparatus includes a charged-particle source, a first condenser lens configured to condense the primary charged-particle beam and operable in a first mode and a second mode, wherein: in the first mode, the first condenser lens is configured to condense the primary charged-particle beam, and in the second mode, the first condenser lens is configured to condense the primary charged-particle beam sufficiently to form a crossover along the primary optical axis. The apparatus further includes a second condenser lens configured to adjust a first beam current of the primary charged-particle beam in the first mode and adjust a second beam current of the primary charged-particle beam in the second mode, the second beam current being larger than the first beam current.