Focused Ion Beam Aperture Slit Masking for Cross-Section Etching
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Solution Overview
Problem
Current focused ion beam processing techniques face inefficiencies in cross-section processing, particularly with high current beams, leading to prolonged processing times and suboptimal edge quality due to rounded edges and unnecessary etching, which decreases operation efficiency.
Innovation Solution
A focused ion beam processing apparatus utilizing an aperture with a slit-shaped opening to mask part of the ion beam, combined with a projection lens and adjusted voltages for Köhler illumination, concentrates probe current near the center for deep etching and reduces waste, achieving a V-shaped cross-section contour without scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high current focused ion beam is used for cross-section processing, then etching speed is improved, but rounded edges and processing lines occur reducing manufacturing precision
Solution Approach 1:
The ion beam is segmented into multiple regions with different current densities by positioning the aperture off-center. The beam cross-section is divided into a high current density region (for rapid etching) and a low current density region (for precise edge processing), allowing simultaneous achievement of high etching speed and good edge quality without requiring separate processing steps
Solution Approach 2:
Different regions of the ion beam are assigned different current density characteristics to perform different functions. The center region provides high current density for fast etching, while the peripheral region provides lower current density for clean edge formation, enabling spatially differentiated processing quality across the beam profile
2Manufacturing precision
If finish processing is performed with a low current beam to reduce rounded edges, then manufacturing precision is improved, but total processing time increases reducing productivity
Solution Approach 1:
The ion beam is segmented into multiple regions with different current densities by positioning the aperture off-center. The beam cross-section is divided into a high current density region (for rapid etching) and a low current density region (for precise edge processing), allowing simultaneous achievement of high etching speed and good edge quality without requiring separate processing steps
Solution Approach 2:
The off-center aperture configuration enables both high current density etching and low current density edge refinement to occur simultaneously in a single continuous processing step, eliminating the need for sequential high-current then low-current processing and thereby maintaining continuous productive action throughout
3Length of stationary object
If a large beam diameter is used for high current processing, then etching depth is improved, but rounded edges occur reducing manufacturing precision
Solution Approach 1:
The ion beam is segmented into multiple regions with different current densities by positioning the aperture off-center. The beam cross-section is divided into a high current density region (for rapid etching) and a low current density region (for precise edge processing), allowing simultaneous achievement of high etching speed and good edge quality without requiring separate processing steps
Solution Approach 2:
The aperture is deliberately positioned asymmetrically (off-center) relative to the ion beam axis, creating an asymmetric current density distribution across the beam cross-section. This asymmetric configuration enables one side of the beam to provide high current for deep etching while the other side provides lower current for sharp edge definition
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 enhances operation efficiency by minimizing unnecessary etching, reducing sputter product adhesion, and improving edge quality by focusing the ion beam to match the required cross-section shape, allowing for deeper etching without additional processing steps.
Implementation Method 1
a condenser lens focusing ions emitted from the ion source into a focused ion beam
Implementation Method 2
a projection lens placed in a beam path between the aperture and the sample stage, and focusing the focused ion beam that passed through the aperture on a predetermined position on the sample
Implementation Method 3
the sample is irradiated with such a focused ion beam having high current and is processed... a cross-section at a desired position is produced
Data Source
AI summary
Provided is a focused ion beam processing apparatus including: an ion source; a sample stage a condenser lens; an aperture having a slit in a straight line shape; a projection lens and the sample stage, wherein, in a transfer mode, by Köhler illumination, with an applied voltage of the condenser lens when a focused ion beam is focused on a main surface of the projection lens scaled to be 100, the applied voltage is set to be less than 100 and greater than or equal to 80; a position of the aperture is set such that the focused ion beam is masked by the aperture with the one side of the aperture at a distance greater than 0 μm and equal to or less than 500 μm from a center of the focused ion beam; and the shape of the slit is transferred onto the sample.