Microfabrication Characterization via Multi-Focal Imaging
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Solution Overview
Problem
Current optical techniques for observing microstructures created by microfabrication processes are inflexible and limited in assessing features below a certain size or dimension, requiring extensive data and mathematical models, and struggle with capturing three-dimensional structures due to resolution and depth of focus constraints.
Innovation Solution
A system that uses a controller coupled with an imaging system and mechatronic support to capture and concatenate images from multiple focal positions, allowing for the analysis of structure characteristics such as roughness, inclination, and geometry, and correlates this information with microfabrication tool data to provide feedback for process improvement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If non-imaging techniques such as ellipsometry, scatterometry, and reflectometry are used to assess substrate characteristics, then measurement precision for small features is improved, but device complexity and data processing requirements increase significantly
Solution Approach 1:
The patent replaces complex mechanical/optical measurement systems (ellipsometry, scatterometry, reflectometry) with a simplified imaging system that captures optical images of substrate features. Instead of using intricate mathematical models and specialized hardware to assess substrate characteristics, the system uses standard imaging technology combined with image processing algorithms to extract feature information, thereby reducing device complexity while maintaining measurement capability
Solution Approach 2:
The patent creates optical copies (images) of substrate features that can be analyzed without direct physical measurement. By capturing images of the substrate and processing these optical copies to extract feature characteristics, the system avoids the need for complex direct measurement hardware and mathematical models, simplifying the overall measurement approach
2Measurement precision
If imaging techniques with higher resolution are used to capture structures, then measurement precision is improved, but depth of focus decreases limiting the amount of 3D structure that can be captured
Solution Approach 1:
The patent segments the imaging process into multiple focal plane captures. Instead of attempting to capture the entire 3D structure in a single image with limited depth of focus, the system captures multiple images at different focal planes and processes them separately. This allows high-resolution imaging of different depth regions while maintaining overall 3D structural information
Solution Approach 2:
The patent transitions from 2D imaging to 3D characterization by capturing images across multiple focal planes (adding the depth dimension). By processing images from different focal positions, the system reconstructs three-dimensional information about substrate features, overcoming the depth of focus limitation of high-resolution optical systems
3Measurement precision
If laser triangulation is used as a scatterometer to locate small structures, then measurement precision for larger structures is improved, but the technique becomes less useful for structures smaller than the wavelength of light
Solution Approach 1:
The patent creates a universal imaging system that can characterize substrate features across a broad range of sizes and dimensions. Instead of being limited to structures larger than the wavelength of light like laser triangulation, or requiring complex models for sub-wavelength features like scatterometry, the system uses optical imaging combined with advanced image processing that adapts to various feature sizes, providing versatile characterization capability
Data Source
AI summary
A system for assessing a structure and the tools and processes used to form the structure is described. 2D images of the structure are captured and processed to obtain 3D information concerning the structure. Both 2D and 3D information is then used to identify and analyze selected characteristics of the structure. This analysis allows for a quality assessment of the structure. The selected characteristics are correlated with information relating to the operation of the tool that carried out the process that at least in part created the structure. The correlation of tool/process information to structure characteristics allows for the generation of feedback that may be used to modify the tool or processed used to form the structure.