Microscopy Sample Thinning With Electron-Transmission Feedback
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Solution Overview
Problem
Current sample preparation methods for microscopy, such as FIB, often result in inaccurate and time-consuming sample thinning, leading to inconsistent results due to the inability to observe minor modifications during milling and requiring manual estimation of material removal, which can be challenging for novice operators and may result in errors.
Innovation Solution
An apparatus that includes an ion source for milling and an electron column for in-situ imaging, where an electron beam is scanned across the sample, and a detector monitors the electron beam's transmission to automatically terminate milling when a preselected threshold is reached, ensuring precise sample thinning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If FIB is used to mill the sample, then material removal capability is improved, but manufacturing precision deteriorates due to inability to observe minor modifications during milling
Solution Approach 1:
The patent implements a feedback mechanism where an electron beam is directed at the sample during ion beam milling, and a detector monitors the electron transmission signal. When the sample thickness reaches a predetermined threshold (indicated by a specific electron transmission level), the system automatically stops the milling process. This real-time feedback loop enables precise control of material removal, resolving the contradiction between high material removal capability and precise thickness control.
2Ease of manufacture
If manual estimation of material removal is used, then operator experience can achieve adequate results, but reliability deteriorates due to operator error and inconsistency
Solution Approach 1:
The system performs self-monitoring and self-control of the milling process. The electron beam detection system automatically measures sample thickness in real-time, and the control system autonomously terminates milling when the target thickness is reached, eliminating the need for operator estimation and judgment. This automation ensures consistent, reliable results without depending on operator skill level.
3Manufacturing precision
If repeated milling and re-imaging cycles are performed, then sample quality can be improved, but productivity deteriorates due to time-consuming manual processes
Solution Approach 1:
The system performs preliminary monitoring of sample thickness during the milling process itself, rather than waiting until after milling is complete. By continuously detecting electron transmission and identifying when the target thickness is reached, the system prevents over-milling and eliminates the need for subsequent re-imaging and re-milling cycles, thereby improving both quality and productivity.
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 accurate, efficient, and repeatable sample thinning, reducing operator error and improving the speed of sample preparation for microscopy, enabling consistent results and minimizing the need for repeated processes.
Implementation Method 1
a primary ion beam strikes the sample surface and sputters an amount of material
Implementation Method 2
an electron beam is directed onto the sample... a detector detects the degree to which the electron beam is blocked by the sample
Data Source
Figure 1
Figure 2
Figure 2A
AI summary
An apparatus for preparing a sample for microscopy is provided that has a milling device that removes material from a sample in order to thin the sample. An electron beam that is directed onto the sample is present along with a detector that detects when the electron beam has reached a preselected threshold transmitted through or immediately adjacent the sample. Once the detector detects the electron beam has reached this threshold, the milling device terminates the milling process.