APT Specimen Preparation for Hard-to-Evaporate and Hollow Regions
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Solution Overview
Problem
Current atom probe tomography (APT) techniques face challenges with hard-to-evaporate materials and hollow regions in semiconductor structures, which hinder ion removal and distort 3D reconstruction, and issues with unidentifiable ions due to overlapping mass spectrum peaks.
Innovation Solution
Identify and replace challenging components with APT-friendly materials, such as capping materials like carbon and oxygen-based organic compounds, cobalt, nickel, or titanium dioxide, using chemical mechanical polishing and deposition processes to create a suitable specimen for APT analysis, ensuring easy evaporation and identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If field evaporation is applied to remove ions from the surface, then ion removal is achieved, but hard-to-evaporate materials block the process and prevent underlying material ions from being removed
Solution Approach 1:
The patent extracts and removes the hard-to-evaporate material layer from the specimen surface before performing atom probe tomography. By taking out the problematic material that blocks field evaporation, the underlying materials can be analyzed without obstruction, directly resolving the contradiction between ion removal efficiency and blockage by difficult-to-evaporate materials
Solution Approach 2:
The patent performs preliminary preparation by removing or modifying the hard-to-evaporate material layer before the actual APT analysis. This preliminary action eliminates the blockage issue in advance, allowing the field evaporation process to proceed efficiently on the underlying materials without encountering resistance from the difficult-to-evaporate layer
2Measurement precision
If hollow regions are present in the specimen, then 3D reconstruction can be performed, but fracture occurs during field evaporation distorting the reconstruction
Solution Approach 1:
The patent converts the harmful effect of hollow regions by filling them with evaporable material. The previously problematic hollow spaces that caused fracture are transformed into solid, evaporable regions. This allows the 3D reconstruction to proceed without fracture while maintaining the ability to analyze the original hollow region's location and characteristics
3Measurement precision
If overlapping mass spectrum peaks are present, then ion identification becomes difficult, but replacing materials improves identifiability
Solution Approach 1:
The patent applies local quality by selectively replacing materials in specific regions where overlapping peaks occur. By modifying only the problematic regions with materials that have distinct mass spectra, the patent improves ion identification accuracy in those specific locations without unnecessarily complicating the entire specimen's material composition
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
Enhances the yield of APT analysis by facilitating the removal of ions from difficult materials, preventing distortion in 3D reconstruction, and improving the identifiability of ions, leading to more accurate dopant concentration and distribution analysis in semiconductor structures.
Implementation Method 1
ions are removed from a surface of an APT specimen through application of an electrical pulse, which is referred to as field evaporation
Implementation Method 2
The lateral location of the ions at the surface(s) of the APT specimen is determined based on, e.g., through a time-of-flight sensing mechanism, a time interval for a decoupled ion to travel to a detector
Data Source
AI summary
The disclosure is directed to techniques in preparing an atom probe tomography (“APT”) specimen. A structure in a semiconductor device is identified as including a test object for an APT procedure. A target region is identified in the structure where an APT specimen will be obtained. The target region is analyzed to determine whether a challenging component feature exists therein. A challenging component may include a hard-to-evaporate material, a hollow region, or a material unidentifiable with respect to the test object, or other structural features that pose a challenge to a successful APT analysis. If it is determined that a challenging component exists in the target region, the challenging component is replaced with a more suitable material before the APT specimen is prepared.