AFM Level Difference Measurement Using Local Height Histograms
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Solution Overview
Problem
Existing methods for measuring level differences on semiconductor substrates face challenges in accurately calculating level differences due to variations caused by warpage, distortion, and in-plane errors, especially when the specimen is warped or distorted, and difficulties in distinguishing between different film heights.
Innovation Solution
A level difference measuring apparatus and method that utilizes an atomic force microscope to measure surface heights, sets a measurement area, generates a histogram of these heights, and calculates level differences by identifying distinct peaks in the histogram to reduce measurement variations and account for specimen placement errors and film thickness variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional level difference measurement methods are used on warped or distorted specimens, then measurement can be performed, but measurement accuracy deteriorates due to warpage, distortion, and in-plane errors
Solution Approach 1:
The measurement area is divided into multiple local regions, and level differences are calculated separately for each region. This segmentation allows the measurement to focus on local characteristics rather than being affected by global specimen warpage or distortion, thereby improving measurement accuracy on non-planar specimens
Solution Approach 2:
The patent applies different measurement strategies to different local regions of the specimen. By identifying regions with significant level differences and focusing measurement resources there, the system achieves higher accuracy in critical areas while being less sensitive to overall specimen deformation
2Productivity
If histogram-based level difference calculation is used, then measurement efficiency is improved, but difficulty in distinguishing different film heights increases when height variations are subtle
Solution Approach 1:
Before performing the full histogram-based level difference calculation, the system first identifies candidate measurement regions and pre-processes the data to enhance relevant features. This preliminary action prepares the data in a way that makes subsequent histogram analysis more effective at distinguishing subtle height differences
Solution Approach 2:
The patent introduces intermediate processing steps between raw measurement data and final histogram analysis, including data filtering and feature enhancement techniques. These intermediary processes preserve subtle height variations while removing noise, enabling the histogram method to detect subtle film height differences effectively
3Area of stationary object
If measurement area is expanded to cover entire specimen, then comprehensive measurement is achieved, but impact of specimen placement errors and warpage increases
Solution Approach 1:
Instead of treating the entire specimen as one measurement area, the patent divides it into multiple smaller local measurement regions. This segmentation allows comprehensive coverage of the specimen while limiting the propagation of placement errors and warpage effects to only local areas, thereby maintaining measurement precision
Solution Approach 2:
The system applies local measurement strategies to different areas of the specimen, focusing on regions with significant features while being less sensitive to areas affected by placement errors. This local approach enables comprehensive measurement coverage while maintaining accuracy in critical regions
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
Enables accurate and efficient calculation of level differences by minimizing the impact of specimen warpage, distortion, and film thickness variations, allowing for precise measurement and defect detection.
Implementation Method 1
An atomic force microscope (AFM) is known as an apparatus for measuring a level difference formed on a semiconductor substrate or the like with high accuracy
Data Source
AI summary
A level difference measuring apparatus that measures a level difference on a specimen surface having unevenness formed thereon includes: an atomic force microscope configured to measure a surface height of each of a plurality of measurement points set on the specimen surface; and a level difference calculation unit configured to calculate the level difference in a measurement target area including the plurality of measurement points. The level difference calculation unit sets a measurement area including at least one level difference portion in the measurement target area, generates a histogram by histogramming the surface heights of the measurement points provided in the measurement area, and calculates, based on the histogram, the level difference of the level difference portion provided in the measurement area.