Charged Particle Beam Inspection Conductive Membrane Charging
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Solution Overview
Problem
Current charged particle beam devices for wafer inspection face challenges in achieving high throughput and uniform specimen charging, particularly at low landing energies and low secondary electron extraction fields, which affects imaging quality and detection sensitivity.
Innovation Solution
A charged particle beam specimen inspection system that includes an emitter, a specimen support table, an objective lens, a charge control electrode with aperture openings, and a flood gun, where a conductive membrane is positioned between the flood gun and the specimen support table to ensure uniform specimen charging and maintain constant surface potential, enhancing imaging quality and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a flood gun is used to charge the specimen, then charging speed is improved, but surface potential uniformity deteriorates due to charging non-uniformity
Solution Approach 1:
A conductive membrane is introduced as an intermediary component between the flood gun and the specimen. This membrane distributes the charged particles emitted by the flood gun across the specimen surface, transforming the non-uniform charging into uniform surface potential distribution while maintaining high charging speed
Solution Approach 2:
The charge control electrode with selectively positioned aperture openings creates locally optimized charging zones. By controlling which areas receive charged particles through the aperture pattern, uniform surface potential is achieved across different regions of the specimen surface
2Measurement precision
If low landing energy is used for surface inspection, then detection sensitivity is improved, but image drift increases due to specimen charging
Solution Approach 1:
The flood gun performs preliminary charging of the specimen surface before the actual inspection process. By pre-establishing a uniform surface potential distribution, the specimen remains electrically stable during low-energy inspection, preventing image drift while maintaining high detection sensitivity
Solution Approach 2:
The conductive membrane creates an equipotential surface on the specimen by distributing charged particles uniformly. This equipotential condition eliminates electric field variations that would cause image drift, allowing stable imaging at low landing energies
3Manufacturing precision
If a conductive membrane is added to improve charging uniformity, then surface potential uniformity is improved, but device complexity increases
Solution Approach 1:
The charge control electrode serves multiple functions: it controls the primary charged particle beam for inspection and simultaneously manages flood gun aperture positioning for uniform charging. This multi-functionality reduces the need for separate control mechanisms, offsetting the added complexity of the conductive membrane
Solution Approach 2:
The conductive membrane is integrated with the charge control electrode structure, combining the charging control and uniforming functions into a single integrated component. This merging approach minimizes the number of discrete parts and simplifies the overall system architecture
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 system achieves high-resolution, large-field-of-view imaging with improved throughput by maintaining constant surface potential and preventing image drift, allowing for efficient pre-charging and dis-charging of specimens, thereby enhancing detection sensitivity and imaging consistency.
Implementation Method 1
a flood gun configured to emit further charged particles for charging of the specimen
Implementation Method 2
an objective lens for focusing the at least one charged particle beam
Implementation Method 3
a conductive membrane is provided which is positioned between the flood gun and the specimen support table
Data Source
AI summary
A charged particle beam specimen inspection system is described. The system includes an emitter for emitting at least one charged particle beam, a specimen support table configured for supporting the specimen, an objective lens for focusing the at least one charged particle beam, a charge control electrode provided between the objective lens and the specimen support table, wherein the charge control electrode has at least one aperture opening for the at least one charged particle beam, and a flood gun configured to emit further charged particles for charging of the specimen, wherein the charge control electrode has a flood gun aperture opening at which a conductive membrane is provided which is positioned between the flood gun and the specimen support table.