Plasma Flood Gun Charge Control for Insulating Sample Imaging
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Solution Overview
Problem
Charged particle imaging systems face challenges with surface charge accumulation on insulating samples, leading to focus drift, image distortion, and reduced throughput due to the need for time-consuming pre-charging methods using traditional flood guns, which affect the efficiency of semiconductor inspection and ion implantation processes.
Innovation Solution
The use of downstream plasma from a plasma flood gun to control surface charge by immersing the sample in plasma and applying bias voltages to achieve rapid and uniform charge neutralization or intentional charging of the sample surface, eliminating the need for separate pre-charging scans and increasing the speed of the surface charge control process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional flood gun methods are used for surface charge control, then charge neutralization can be achieved, but the process is time-consuming and reduces throughput
Solution Approach 1:
The patent replaces the mechanical scanning system of traditional flood guns with a plasma-based charge control method. Plasma is generated in a separate chamber and transported to the sample surface, eliminating the need for mechanical scanning and significantly reducing the time required for surface charge control while maintaining effective charge neutralization
Solution Approach 2:
The patent uses gas flow dynamics to transport plasma from the generation chamber to the sample surface. By controlling gas pressure and flow rates, the plasma is delivered efficiently to the target area, enabling rapid charge control without mechanical movement and improving throughput
2Reliability
If separate pre-charging scans are performed, then surface charge can be controlled, but imaging time increases and efficiency decreases
Solution Approach 1:
The patent combines the surface charge control function with the imaging process by delivering plasma during the imaging scan. This integration eliminates the need for separate pre-charging scans, as the plasma is continuously supplied to maintain proper surface charge conditions throughout the imaging process, thereby reducing total imaging time
Solution Approach 2:
The plasma delivery system is designed to pre-charge the sample surface before imaging begins and maintain charge control during imaging. By establishing the proper surface charge state in advance and sustaining it throughout the process, the system eliminates time losses associated with intermediate charge control operations
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 method significantly enhances the speed of surface charge control, allowing for faster pre-charging and neutralization, thereby improving the throughput and efficiency of charged particle imaging and ion implantation processes by eliminating the need for separate pre-charging scans and maintaining image quality.
Implementation Method 1
A plasma flood gun may be used to generate plasma and direct it onto a sample surface in a charged particle system
Implementation Method 2
The secondary ions and electrons are then collected by one or several charged particle detectors to form a high-resolution image of the surface
Data Source
AI summary
A method for altering surface charge on an insulating surface of a first sample includes generating first plasma inside a plasma source, causing the first plasma to diffuse into a first vacuum chamber to generate second downstream plasma, immersing the first sample in the second downstream plasma, and applying a first bias voltage to a conductive layer of the first sample, or applying a first bias voltage to a metal holder that holds the first sample.