Particle Optical System for SACP Crystal Orientation Analysis
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Solution Overview
Problem
Conventional SACP methods face limitations in accurately measuring the orientation and internal stress states of crystals due to difficulties in precisely controlling the angle of incidence and impingement location of charged particle beams, leading to suboptimal channeling pattern analysis.
Innovation Solution
A particle optical system with an objective lens, upstream and downstream beam deflectors, and an aberration corrector allows for independent adjustment of the angle of incidence and impingement location, enabling rapid and precise measurement of particle intensities at multiple angles, thereby enhancing the resolution and accuracy of selected area channeling patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the angle of incidence is varied to obtain channeling pattern information, then the measurement precision of crystal orientation is improved, but the impingement location on the object surface changes, leading to loss of spatial resolution
Solution Approach 1:
The patent divides the beam path into multiple independent control sections: a first beam deflector for angle control and a second beam deflector for position control. This segmentation allows independent adjustment of incidence angle and impingement location, resolving the contradiction between obtaining angular channeling information and maintaining spatial resolution.
2Adaptability or versatility
If conventional beam deflectors are used to vary the angle of incidence, then the measurement of channeling patterns is enabled, but the impingement location on the sample surface cannot be kept constant, reducing measurement accuracy
Solution Approach 1:
The beam deflection system is segmented into two independent deflectors: the first deflector varies the angle of incidence while the second deflector compensates for position drift. This allows the system to adaptively vary angles while maintaining precise impingement location control.
Solution Approach 2:
The system uses feedback control where the second beam deflector is adjusted based on the angle variation introduced by the first deflector to maintain constant impingement location. This feedback mechanism ensures that location precision is preserved while angle adaptability is achieved.
3Manufacturing precision
If the beam is focused to a point to achieve high spatial resolution, then the penetration depth decreases, reducing the channeling effect signal strength
Solution Approach 1:
The patent changes the beam parameters by using a collimated beam with larger spot size to increase penetration depth and secondary particle generation, while using beam deflectors to maintain angular precision. This parameter change allows simultaneous achievement of sufficient signal strength and angular measurement precision.
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 the detection of particle intensities for at least 100 different angles of incidence at a constant impingement location, providing detailed channeling patterns and crystal properties analysis, even at large angles of incidence, with improved focusing and aberration correction.
Implementation Method 1
an objective lens for focusing the beam
Implementation Method 2
a first beam deflector located upstream of the objective lens in a beam path of the beam... adjusting an excitation of the first beam deflector for adjusting an angle of incidence of the beam on the object surface
Implementation Method 3
an aberration corrector located between the first beam deflector and the objective lens in the beam path
Data Source
Figure 1
Figure 2
AI summary
A SACP (selected area channeling pattern) method comprising: directing a beam (9) of charged particles onto an object surface (23) of an object (25) using a particle optical system (1); and detecting intensities of particles emanating from the object; wherein the method comprises: (a1) adjusting an excitation of a second beam deflector (17,19) for adjusting an impingement location (29) of the beam on the object surface; (a2) adjusting an excitation of a first beam deflector (11,13) for adjusting an angle (Ψ) of incidence of the beam on the object surface without changing the impingement location and detecting the intensity; and (a3) repeating the adjusting of the excitation of the first beam deflector for adjusting the angle of incidence without changing the impingement location such that a corresponding intensity is detected (35) for each of at least 100 different angles of incidence at the same impingement location. The application also relates to a charged particle optical system (1) for performing the method.