SEM Electron Beam Flooding for Faster Voltage Contrast Inspection
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Solution Overview
Problem
Traditional charged particle flood guns in charged particle beam inspection systems face limitations such as reduced controllability, accuracy, and cost constraints, particularly in inspecting small memory devices, due to their independent operation and simplified controls, which complicates switching between flooding and inspection modes and restricts precise controllability.
Innovation Solution
A charged particle beam system with a controller that can switch between a defocused flooding mode and a focused inspection mode, utilizing the primary electron beam source of a scanning electron microscope (SEM) for both functions, allowing for adjustable current levels and beam spot sizes through a set of apertures, enabling efficient pre-charging and imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated e-beam flood gun is used for pre-charging, then voltage contrast defect signal is enhanced, but device complexity and cost increase
Solution Approach 1:
The primary electron beam source is designed to perform multiple functions: both inspection imaging and flood gun pre-charging. By configuring the beam source to operate in different modes (inspection mode with focused beam at lower current, flooding mode with defocused beam at higher current), the system eliminates the need for a separate dedicated flood gun, thereby reducing device complexity and cost while maintaining voltage contrast defect signal enhancement capability
Solution Approach 2:
The inspection beam source and flood gun are merged into a single primary electron beam source. The system combines the functionality of both components by using the same electron source for both inspection and pre-charging operations, simplifying the overall system architecture and reducing the number of required components
2Quantity of substance
If a dedicated e-beam flood gun is used, then flooding capability is improved, but switching time between modes increases
Solution Approach 1:
The system dynamically adjusts operating parameters (beam current, focus/defocus state) of the primary electron beam source to switch between inspection and flooding modes. By using electromagnetic lenses and aperture controls that can rapidly change beam characteristics, the system achieves fast mode switching without the delays associated with mechanical flood gun engagement and disengagement
Solution Approach 2:
The system changes operational parameters of the electron beam source to transition between modes: increasing beam current and defocusing the beam for flooding mode, then decreasing current and refocusing for inspection mode. These parameter changes are achieved through electronic control of lens currents and aperture positions, enabling rapid mode switching
3Ease of manufacture
If traditional flood gun with simplified controls is used, then ease of manufacture is improved, but controllability and accuracy are reduced
Solution Approach 1:
The primary electron beam source is designed to perform both inspection and flooding functions with precise controllability. By using the same sophisticated beam source for both purposes, the system maintains high measurement precision and beam controllability while avoiding the manufacturing complexity of adding a separate flood gun with its own control systems
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 solution enables rapid switching between flooding and inspection modes, improving sensitivity and throughput by leveraging the SEM's native electron optics for precise control of beam current and spot size, reducing waiting time and increasing inspection efficiency while eliminating the need for a dedicated flood gun.
Implementation Method 1
at least one electromagnetic lens configured to control focusing of the charged particle beam
Implementation Method 2
a charged particle source configured to emit a charged particle beam along an optical axis
Data Source
AI summary
Systems and methods for implementing charged particle flooding in a charged particle beam apparatus are disclosed. According to certain embodiments, a charged particle beam system includes a charged particle source and a controller which controls the charged particle beam system to emit a charged particle beam in a first mode where the beam is defocused and a second mode where the beam is focused on a surface of a sample.