Lamina Specimen Thickness Control via Dual-Beam Sputtering
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Solution Overview
Problem
Current methods for creating lamina samples for transmission electron microscopy, such as sputtering-etching using focused ion beams, face challenges in accurately controlling the thickness and efficiency of the process, particularly as device structures become finer and more complex.
Innovation Solution
The method involves using a dual-beam apparatus with two focused ion beams and a tilt stage to measure and control the thickness of the lamina sample by irradiating one beam parallel to the side wall, allowing for precise etching and observation, and alternating between high and low acceleration voltage conditions to optimize the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sputtering-etching working is performed by focused ion beam to create lamina sample, then the lamina can be formed in sample surface, but the thickness control of lamina is difficult and time-consuming
Solution Approach 1:
The patent implements real-time thickness measurement feedback during the sputtering-etching process. A thickness measurement unit continuously monitors the lamina thickness while the focused ion beam is working, and this measurement information is fed back to control the etching process, enabling automatic termination when the target thickness is reached. This feedback mechanism eliminates the need for separate measurement steps and achieves both precise thickness control and reduced processing time.
Solution Approach 2:
The patent enables continuous simultaneous operation of the focused ion beam for etching and the thickness measurement system for monitoring. Both actions occur concurrently during the same working period, rather than sequentially. This continuous dual-action approach maximizes efficiency by eliminating idle time between etching and measurement operations.
2Measurement precision
If multiple measurement and working steps are performed sequentially, then the thickness can be measured and confirmed, but the total processing time increases
Solution Approach 1:
The patent merges the etching function and the measurement function into a single integrated system that operates simultaneously. The focused ion beam performs etching while the thickness measurement unit performs real-time monitoring during the same time period and spatial region. This merging of functions eliminates the need for separate sequential operations, thereby maintaining measurement precision while significantly improving processing efficiency.
3Stability of the object's composition
If the sample stage is tilted for uniform thickness working, then the lamina thickness can be uniformized, but the control method for thickness is not established
Solution Approach 1:
The patent implements real-time thickness measurement feedback during the tilted-stage etching process. The measurement unit continuously monitors the lamina thickness even when the sample stage is tilted, and this feedback information enables precise control of the etching depth. This resolves the issue of lacking thickness control methodology while maintaining the benefits of tilted-stage uniform etching.
Solution Approach 2:
The patent utilizes real-time measurement data to dynamically adjust etching parameters such as beam current, acceleration voltage, or etching time based on the actual thickness progression. This parameter adjustment based on feedback ensures uniform thickness control even when the sample stage is tilted, establishing a systematic thickness control methodology.
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 enables accurate and rapid control of lamina thickness, reducing damage and improving uniformity, allowing for efficient production of lamina samples suitable for high-resolution microscopy.
Implementation Method 1
Sputtering-etching-working a desired place of the sample surface by the focused ion beam
Implementation Method 2
scan-irradiating a 2nd focused ion beam from a direction parallel to a side wall of the lamina having been formed
Data Source
AI summary
In a method of making a lamina specimen, first and second ion beams are simultaneously used to sputter etch first and second side walls of a lamina region at the same time under first and second ion beam conditions. A scanning ion microscope observation of the lamina region is made using the second ion beam while sputter etching of the first and second side walls is continued using the first ion beam until the thickness of the lamina has a predetermined value.