Focused Ion Beam Sample Preparation for Unobstructed EBSP Detection
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Solution Overview
Problem
Conventional methods face difficulties in obtaining accurate electron back-scattering patterns (EBSP) when the sample shape obstructs the optical paths of backscattered electrons, especially when the target of observation is buried or has complex geometries.
Innovation Solution
A sample preparation apparatus with a focused ion beam column and an irradiation area setting unit that creates a tilted surface with an angle of 67.5° or more and less than 90° to the normal direction, allowing for unobstructed detection of backscattered electrons by forming a groove that does not block the optical paths to the detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the target of observation is exposed by focused-ion-beam processing, then the target becomes accessible for electron beam irradiation, but the processed sample shape blocks the optical paths of backscattered electrons
Solution Approach 1:
The invention introduces a tilted surface that connects the observation field to the sample surface, creating a three-dimensional pathway for backscattered electrons. This tilted surface, formed by focused ion beam processing at specific angles, allows electrons to travel from the observation field to the detector without being blocked by the sample geometry, effectively adding a dimensional solution to the path-blocking problem.
Solution Approach 2:
The invention applies different surface characteristics to different regions: the observation field maintains its original properties for electron beam interaction, while the surrounding area develops a tilted surface with specific geometric properties (67.5° or more and less than 90° from normal direction). This localized geometric modification ensures unobstructed electron paths without altering the observation field itself.
2Measurement precision
If conventional sample preparation methods are used, then the target can be exposed, but multiple machining steps and extended time are required
Solution Approach 1:
The invention performs the tilted surface formation as part of the initial focused ion beam processing step, rather than requiring separate machining operations afterward. By setting the irradiation area to include both the observation field exposure and the tilted surface formation simultaneously, the preparation is completed in one integrated operation, significantly reducing total processing time.
3Ease of operation
If the sample shape is modified to expose the target, then observation is enabled, but the optical paths for backscattered electrons are obstructed
Solution Approach 1:
The tilted surface creates a three-dimensional electron pathway that bypasses the obstruction problem. By forming this angled surface connecting the observation field to the detector region, backscattered electrons can travel along this elevated path without being blocked by sample structures that would obstruct straight-line paths from a flat surface observation.
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
Enables the formation of accurate EBSPs by ensuring that backscattered electrons can reach the detector without obstruction, reducing machining steps and time required to expose the observation field.
Implementation Method 1
a focused ion beam column configured to apply a focused ion beam to the sample and process the sample
Implementation Method 2
an electron beam in order to detect backscattered electrons
Implementation Method 3
backscattered electrons emitted from the sample irradiated with an electron beam
Data Source
AI summary
Provided is an apparatus for preparing a sample including: a sample stage that supports a sample; a focused ion beam column that applies a focused ion beam to the same sample and processes the sample; and an irradiation area setting unit that sets a focused-ion-beam irradiation area including a first irradiation area used to form an observation field irradiated with an electron beam in order to detect backscattered electrons and a second irradiation area used to form a tilted surface tilted with respect to the normal line of the observation field with an angle of 67.5° or more and less than 90°.