Charged Particle Beam Apparatus Temperature Feedback Control
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Solution Overview
Problem
In CD-SEM devices, the time required for movement/image capture/ measurement (MAM time) is significantly reduced due to frequent adjustments needed to maintain proper electron beam conditions, leading to inefficiencies and difficulties in evaluating the equilibrium state of the objective lens, especially when measuring diverse patterns like deep grooves and deep holes, where astigmatism or axis shifts occur.
Innovation Solution
A charged particle beam device with an optical element and an adjustment element, controlled by a device that determines the difference between initial and equilibrium states of the optical element, allowing for automatic adjustments only when necessary, thus minimizing unnecessary interruptions and maintaining high-precision measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequent automatic adjustments are performed to maintain proper beam conditions, then measurement precision is improved, but productivity deteriorates due to increased MAM time
Solution Approach 1:
The system continuously monitors the objective lens temperature and compares it against the equilibrium temperature to determine when adjustments are necessary. This feedback mechanism enables the system to perform adjustments only when the temperature deviation exceeds a threshold, rather than frequently interrupting measurements for routine checks, thus maintaining precision while improving productivity
Solution Approach 2:
The system automatically determines the equilibrium temperature and monitors its own state without external intervention. The control device autonomously decides when adjustments are needed based on temperature monitoring, eliminating the need for manual assessment and reducing unnecessary interruptions to the measurement process
2Reliability
If measurement is interrupted to allow device stabilization, then reliability is improved, but loss of time increases
Solution Approach 1:
The system performs temperature monitoring and equilibrium determination in advance during measurement operations. By continuously tracking the temperature and predicting when equilibrium will be reached, the system can prepare for adjustments without interrupting the measurement flow, thus maintaining reliability while minimizing time loss
Solution Approach 2:
The temperature monitoring and equilibrium assessment operate continuously during measurements without interruption. This continuous operation allows the system to maintain measurement accuracy while avoiding the need to stop measurements for stabilization periods, thereby reducing time loss
3Measurement precision
If multiple sensors and image processing techniques are added to determine adjustment necessity, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system extracts and monitors only the critical parameter - objective lens temperature - to determine adjustment necessity. By focusing on this single key parameter rather than analyzing multiple image quality metrics or using complex sensor arrays, the system achieves accurate adjustment timing while maintaining simple device configuration
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 configuration enhances throughput and precision by avoiding unnecessary adjustments, allowing for real-time monitoring and automatic adjustments based on temperature fluctuations, ensuring proper beam conditions without interrupting the measurement process.
Implementation Method 1
an objective lens which focuses a charged particle beam
Implementation Method 2
an alignment coil which adjusts an optical axis of the objective lens
Implementation Method 3
a charged particle source; an objective lens which focuses a charged particle beam emitted from a charged particle source
Data Source
AI summary
A charged particle beam device is provided that performs proper beam adjustment while suppressing a decrease in MAM time, with a simple configuration without adding a lens, a sensor, or the like. The charged particle beam device includes: an optical element which adjusts a charged particle beam emitted from a charged particle source; an adjustment element which adjusts an incidence condition of the charged particle beam with respect to the optical element; and a control device which controls the adjustment element, wherein the control device determines a difference between a first feature amount indicating a state of the optical element based on the condition setting of the optical element, and a second feature amount indicating a state where the optical element reaches based on the condition setting and executes adjustment by the adjustment element when the difference is greater than or equal to a predetermined value.