Beam Current Feedback Control for Stable Charged Particle Inspection
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Solution Overview
Problem
Charged particle beam systems lack real-time monitoring and adjustment capabilities for beam current, leading to inaccurate images and reduced image quality due to fluctuations in beam current during inspection of sub-100 nanometer IC components.
Innovation Solution
Implementing a feedback loop system with a first anode aperture to measure the current of an emitted beam and a controller to adjust the extractor voltage supply based on feedback signals, maintaining the beam current within a setpoint threshold, thereby stabilizing the beam current in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If real-time feedback loop is implemented to stabilize beam current, then image quality and gray level stability are improved, but device complexity increases
Solution Approach 1:
The patent implements a feedback loop that continuously monitors beam current using a first anode aperture and adjusts the extractor voltage supply based on the measured current to maintain it within a setpoint threshold. This closed-loop control system stabilizes beam current in real-time, ensuring consistent image quality and gray levels during extended IC inspections.
Solution Approach 2:
The system automatically monitors and adjusts its own beam current without external intervention. The feedback loop self-regulates by detecting current deviations and correcting them through voltage adjustment, enabling the system to maintain optimal operating conditions autonomously during inspection processes.
2Manufacturing precision
If beam current is stabilized using feedback loop, then inspection accuracy is improved, but measurement and control difficulty increases
Solution Approach 1:
The feedback loop continuously measures beam current using a dedicated first anode aperture and compares it against a setpoint threshold. When deviations are detected, the system automatically adjusts the extractor voltage supply to bring the current back within acceptable ranges, ensuring high inspection accuracy for sub-100 nanometer IC features.
Solution Approach 2:
The first anode aperture serves as an intermediary measurement device that indirectly monitors beam current without significantly disturbing the primary beam path. This intermediary approach simplifies the measurement process while maintaining measurement accuracy, as the aperture provides a controlled interface for current detection.
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 ensures high-quality images with stable gray levels and critical dimension stability over extended periods, improving the accuracy and repeatability of IC inspections.
Implementation Method 1
a first anode aperture configured to measure a current of an emitted beam during inspection of a sample
Implementation Method 2
adjusting a voltage of an extractor voltage supply based on the feedback signal during inspection of the sample such that a difference between an adjusted current of the emitted beam and the setpoint current is below the threshold value
Data Source
AI summary
Apparatuses, systems, and methods for adjusting beam current using a feedback loop are provided. In some embodiments, a system may include a first anode aperture configured to measure a current of an emitted beam during inspection of a sample, wherein the first anode aperture is positioned in an environment that is configured to support a vacuum pressure of less than 3×10−10 torr and a controller including circuitry configured to cause the system to perform: generating a feedback signal when a difference between the measured current and a setpoint current exceeds a threshold value and adjusting a voltage of an extractor voltage supply based on the feedback signal during inspection of the sample such that a difference between an adjusted current of the emitted beam and the setpoint current is below the threshold value.