3D Contact Area Measurement in Semiconductor Structures
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Solution Overview
Problem
Current two-dimensional measurement techniques for determining contact areas between 3D structures in integrated semiconductor samples are imprecise due to material removal inaccuracies and difficulty in locating the contact position, limiting measurement precision and affecting the accuracy of semiconductor performance.
Innovation Solution
A 3D measurement technique using a slice and image approach with focused ion beam (FIB) and scanning electron microscopy (SEM) to obtain cross section images, followed by image registration and 3D model generation to determine the relative overlap and size of contact areas between 3D structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If material is removed from above the contact area to enable SEM imaging, then the contact area becomes accessible for measurement, but the material removal is imprecise affecting measurement accuracy
Solution Approach 1:
The patent transitions from 2D surface imaging to 3D tomographic imaging by acquiring cross-sectional images at multiple depths and reconstructing a 3D model. This dimensional change allows measurement of contact areas without relying on precise material removal, as the 3D reconstruction can virtually section the structure at any depth.
Solution Approach 2:
The patent introduces a 3D model as an intermediary between the raw imaging data and the final contact area measurement. This model allows for virtual sectioning and precise localization of contact areas without physical material removal, thereby avoiding the precision problems associated with physical sectioning.
2Measurement precision
If material is removed from above and below the contact area for TEM imaging, then the contact area becomes accessible for transmission imaging, but the material removal is imprecise affecting measurement accuracy
Solution Approach 1:
The patent uses 3D tomographic reconstruction to enable virtual transmission-like imaging through the accumulation of cross-sectional data, eliminating the need for physical thinning of the sample for TEM-style imaging while maintaining measurement precision.
Solution Approach 2:
The patent creates a digital 3D copy of the semiconductor structure through tomographic reconstruction, allowing for virtual sectioning and measurement without physical manipulation of the actual sample, thereby preserving the original structure's integrity and precision.
3Measurement precision
If material is removed to enable contact area imaging, then the contact area becomes accessible, but the exact position of the contact becomes difficult to locate
Solution Approach 1:
The patent performs preliminary 3D reconstruction of the entire structure before attempting to locate contact areas. This preliminary action creates a complete digital model that preserves all structural information, allowing for subsequent precise localization of contacts without having physically removed material that might have provided localization cues.
Solution Approach 2:
The 3D model serves as an intermediary that retains all structural information from the original sample. This digital representation allows for precise contact localization through virtual sectioning and analysis, eliminating the need to physically preserve structural features for localization purposes.
4Measurement precision
If 2D measurement techniques are used for contact area determination, then the measurement process is simpler, but the measurement precision is limited
Solution Approach 1:
The patent employs 3D tomographic imaging to capture contact area information from multiple angles and depths, then uses computational algorithms to reconstruct the 3D structure and calculate contact areas. This approach trades increased measurement complexity for significantly improved precision, as the 3D data provides comprehensive information about contact geometry that 2D imaging cannot capture.
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 measurement accuracy of contact areas, allowing precise determination of contact size and alignment, which is crucial for semiconductor performance by overcoming inaccuracies in material removal and positioning challenges.
Implementation Method 1
obtaining the first and second cross section images includes subsequently removing a cross section surface layer of the integrated semiconductor sample with a focused ion beam
Implementation Method 2
imaging the new cross section of the integrated semiconductor sample with a scanning electron microscope
Data Source
AI summary
A method of determining a size of a contact area between a first 3D structure and a second 3D structure in an integrated semiconductor sample, includes: obtaining a first cross section image and a second cross section image parallel to the first cross section image, wherein obtaining the first and second cross section images includes subsequently removing a cross section surface layer of the integrated semiconductor sample using a focused ion beam to make a new cross section accessible for imaging, and imaging the new cross section of the integrated semiconductor sample with an imaging device; performing image registration of the obtained cross section images and obtaining a 3D data set; determining a 3D model representing the first 3D structure and the second 3D structure in the 3D data set; and determining a relative overlap of the first 3D structure with the second 3D structure based on the 3D model.