APT Specimen Preparation Without Welding for Higher Mass Resolution
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Solution Overview
Problem
Existing atom probe tomography (APT) techniques face challenges in efficiently forming specimens that provide high mass resolution power (MRP) and mechanical robustness while maintaining simplicity and efficiency in the preparation process.
Innovation Solution
The APT specimen is directly formed on a wafer region under test, using laser patterning to create a trench and bump structures, followed by low-kV focused ion beam (FIB) milling to sharpen the tips, ensuring the specimen is integrally connected to the substrate without welding materials, thereby improving MRP and mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional APT specimen preparation methods are used, then mechanical robustness may be improved, but mass resolution power (MRP) deteriorates due to welding materials and complex preparation processes
Solution Approach 1:
The invention extracts and eliminates welding materials from the specimen preparation process by directly forming the APT specimen on the wafer region under test. The bump structure is created through laser patterning and FIB milling without requiring welding, thereby removing the source of mass resolution degradation while simplifying the preparation process.
Solution Approach 2:
The invention replaces traditional mechanical welding processes with a direct formation approach using laser patterning and focused ion beam milling. This substitution eliminates the mechanical complexity of welding operations and associated materials, improving both mass resolution power and process simplicity.
2Strength
If welding materials are used to form APT specimens, then mechanical robustness is improved, but specimen integrity deteriorates due to contamination and complex procedures
Solution Approach 1:
The invention extracts welding materials from the preparation process entirely. The bump structure is formed directly on the wafer through laser patterning and FIB milling, eliminating welding materials that would otherwise contaminate the specimen and compromise its integrity.
Solution Approach 2:
The wafer structure itself serves as the substrate for the APT specimen. The bump structure is formed directly on the wafer region under test, allowing the specimen to be self-supported and eliminating the need for external welding materials, thereby maintaining specimen integrity.
3Measurement precision
If complex specimen preparation procedures are used, then specimen quality may be improved, but preparation efficiency deteriorates
Solution Approach 1:
The invention merges multiple preparation steps into an integrated process. Laser patterning creates the trench and bump structure, followed by FIB milling to sharpen the tip. This combined approach achieves high specimen quality while reducing the number of separate procedures required, thereby improving preparation efficiency.
Solution Approach 2:
The laser patterning step performs preliminary shaping of the bump structure, creating the basic geometry before the final FIB milling step. This preliminary action reduces the workload for subsequent processing steps, improving overall preparation efficiency while maintaining specimen quality.
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
The method results in an APT specimen with enhanced MRP and mechanical robustness, enabling more accurate and reliable analysis with improved specimen integrity and a simpler, efficient preparation process.
Implementation Method 1
a laser patterning is conducted to form a trench in the DUT and one or more bump structures in the trench
Implementation Method 2
a second patterning process, e.g., a low-kV gas ion milling using a dual-beam focused ion beam (FIB) microscopes, is then conducted on the bump structures to form the dimensions of the bump structures
Data Source
AI summary
The disclosure is directed to techniques in preparing an atom probe tomography (“APT”) specimen. The disclosed techniques form an APT specimen or sample directly on a DUT region on a wafer. The APT specimen is formed integrally to the substrate or the support structure, e.g., a carrier, under the APT specimen. A laser patterning is conducted to form a trench in the DUT and one or more bump structures in the trench. The laser patterning is relatively coarse and forms a coarse surface texture on each of the bump structures. A low-kV gas ion milling using a dual-beam focused ion beam (“FIB”) microscopes is then conducted to shape the bump structures into APT specimen.