Electron Beam Imaging Apparatus with Integrated Flood Gun
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Solution Overview
Problem
Conventional electron beam imaging systems require lengthy procedures for charge equalization, involving separate flooding and inspection phases, which significantly increase the overall time required for sample inspection and reduce throughput due to the need to move the sample between the flood gun and the scanning electron microscope, leading to potential image quality degradation over time.
Innovation Solution
An electron beam imaging apparatus that integrates a flood gun to provide a flood beam coaxially with the primary beam, allowing for rapid switching between flood and image modes, enabling in-situ charge control and minimizing charge dissipation, with the ability to switch between modes in less than 1 second, thereby facilitating continuous inspection without interrupting the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate flooding and inspection phases are used with sample movement between flood gun and SEM, then charge equalization is achieved, but inspection time increases and throughput decreases
Solution Approach 1:
The patent combines the flood gun and scanning electron microscope into a single integrated system, allowing both flooding and inspection to occur in the same chamber without sample movement. The flood gun is positioned to deliver electrons to the sample while the SEM observes the same area, merging two previously separate functions into one unified apparatus.
Solution Approach 2:
The integrated system enables continuous operation by eliminating the interruption caused by sample transfer. The flood gun can operate continuously or in pulsed modes while the SEM maintains continuous observation, ensuring uninterrupted inspection流程和 maintaining charge equalization without breaking the inspection sequence.
2Reliability
If sample is moved between flood gun and SEM for sequential flooding and inspection, then charge control is achieved, but image quality degrades over time
Solution Approach 1:
By merging the flood gun and SEM into one integrated system observing the same sample area, the patent eliminates sample movement and positioning errors. The flood beam and inspection beam are spatially co-aligned, ensuring that the same region receives charge equalization and immediate inspection without relocation, thereby maintaining image quality and spatial accuracy.
3Reliability
If flood gun operates continuously for charge equalization, then charge distribution is maintained, but inspection speed decreases
Solution Approach 1:
The flood gun operates in periodic or pulsed modes rather than continuously, synchronizing its operation with the inspection cycle. Electrons are delivered in controlled bursts between or during inspection lines, maintaining charge equalization while allowing the inspection process to proceed at high speed without continuous flood beam interference.
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 allows for efficient charge control and image acquisition with high current density electrons, reducing inspection time and maintaining image quality by eliminating the need to move the sample for flooding, thus enhancing the throughput of the inspection process.
Implementation Method 1
The first device includes an electron source configured to provide a flood beam of charged particles to a first area of the sample
Implementation Method 2
Typical flood gun hardware includes a high current filament which heats a metal tip, causing emission of electrons toward an extractor electrode
Implementation Method 3
The extractor controls the number of electrons which are emitted towards the wafer and can be used to turn on or turn off (blank) the beam
Implementation Method 4
A Wehnelt electrode positioned close to the wafer surface creates an electric field to control the number of electrons which stay on the wafer
Implementation Method 5
The second device is configured to generate a primary beam of electrons and characterize an interaction between the primary beam and a second area of the sample within the first area
Data Source
AI summary
Embodiments of the present disclosure are directed to an electron beam imaging/inspection apparatus having an electron source device to direct flood electrons on a sample immediately before image acquisition or inspection. The apparatus comprises a first device configured to charge a sample in a first mode, wherein the first device includes an electron source configured to provide a flood beam of charged particles to a first area of the sample. The apparatus also comprises a second device configured to generate a primary beam of electrons and characterize an interaction between the primary beam and a second area of the sample within the first area in a second mode. The apparatus is configured to switch from the first mode to the second mode less than 1 second.