FIB Scan Angle Rotation for Uniform Semiconductor Milling
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Solution Overview
Problem
The curtaining effect in focused ion beam (FIB) milling processes leads to uneven material removal and irregularities due to interactions between the ion beam and semiconductor materials with different physical properties, limiting the range of materials that can be effectively processed without encountering this issue.
Innovation Solution
The method involves determining specific angles for the incidence and rotation of the ion beam and semiconductor sample to adjust the milling direction and plane, using a controlled ion beam device with a control unit to adapt the scan line based on calculated angles, allowing for precise control of the milling process without mechanical rearrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the ion beam is used to mill semiconductor materials with different physical properties, then material removal capability is improved, but the curtaining effect causes uneven material removal and irregularities
Solution Approach 1:
The patent implements dynamic rotation of the semiconductor sample during the FIB milling process. The control unit rotates the sample around its central axis at a predetermined rotation speed while the ion beam scans across the surface. This dynamic rotation ensures that the ion beam interacts with different crystal orientations and material regions sequentially, averaging out the curtaining effect and achieving uniform material removal across materials with different physical properties.
Solution Approach 2:
The patent applies periodic rotation of the semiconductor sample during milling. The sample is rotated continuously at a controlled speed, creating periodic exposure of different surface regions to the ion beam. This periodic action distributes the milling stress uniformly across the sample surface and prevents localized accumulation of the curtaining effect, thereby improving material removal uniformity.
2Manufacturing precision
If the sample rotation angle is adjusted to mitigate the curtaining effect, then material removal uniformity is improved, but the complexity of navigating and adjusting rotation angles increases
Solution Approach 1:
The system performs self-adjustment through automated control. The control unit automatically calculates the optimal rotation angle based on the incident beam angle and predetermined rotation speed, eliminating the need for manual navigation and adjustment. The system self-regulates the rotation parameters to achieve optimal milling conditions, reducing operational complexity while maintaining high precision.
Solution Approach 2:
The control unit continuously monitors the milling process and adjusts the sample rotation angle based on feedback from the incident beam angle and material removal characteristics. This closed-loop control ensures that the rotation angle is optimally adjusted in real-time to mitigate the curtaining effect, simplifying the operation while achieving precise milling uniformity.
3Measurement precision
If the ion beam diameter is reduced to improve lateral measurement resolution, then resolution is improved, but the beam current and milling efficiency decrease
Solution Approach 1:
The patent employs dynamic sample rotation during the milling process. By rotating the sample while using a focused ion beam, the system achieves efficient material removal even with reduced beam diameter. The rotation distributes the milling action across different regions, compensating for the lower beam current and maintaining overall milling efficiency while preserving high lateral measurement resolution.
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 precise control of the milling process, reducing the curtaining effect and improving the uniformity of material removal, enabling the processing of a wider range of materials with enhanced precision and accuracy.
Implementation Method 1
the ion beam, typically composed of Gallium ions interacts with the target material and causes uneven material removal
Data Source
AI summary
A method for operating an ion beam device comprises determining an incidence angle at which an ion beam of the ion beam device hits an upper top surface of a semiconductor sample and a rotation angle for the semiconductor sample around a rotation axis extending perpendicular to the upper top surface. The method also includes rotating the semiconductor sample around the rotation axis by the rotation angle. The method further includes determining a scan angle between an adapted scan line along which the ion beam is moved when hitting the upper top surface and a default scan line of the ion beam extending parallel to the upper top surface of the semiconductor sample. Determining the scan angle is based on the rotation angle and the incidence angle. The scan line is adapted to the adapted scan line based on the determined scan angle.