Composite Metrology Model for High-Aspect Ratio Structures
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Solution Overview
Problem
Current methods for measuring critical dimensions of high-aspect ratio structures, such as optical critical dimension (OCD) metrology tools and transmission small angle X-ray scattering (T-SAXS) techniques, face limitations in accuracy and throughput, particularly in high-volume production processes, with OCD tools being inaccurate due to light decay and T-SAXS suffering from low signal strength.
Innovation Solution
A metrology system combining a high-resolution reference metrology tool, like X-ray scattering, with a high-throughput optical metrology tool, using a controller to generate geometric and material models, forming a composite model for accurate profile determination of high-aspect ratio structures, thereby enhancing measurement precision and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If optical critical dimension (OCD) metrology tools are used to measure critical dimensions of HAR structures, then throughput is maintained, but measurement precision deteriorates due to light decay with sample depth
Solution Approach 1:
The patent introduces an intermediary approach by using optical metrology tools with modified modeling techniques that act as a mediator between the need for high throughput and the requirement for accurate measurement of deep HAR structures. The system uses optical signals as an intermediary to indirectly probe the HAR structure profile through scattering patterns, avoiding direct penetration issues while maintaining measurement capability.
Solution Approach 2:
The patent applies parameter changes by modifying the optical measurement parameters and modeling approaches. Instead of relying on traditional OCD modeling that assumes simple profiles, the system changes the modeling parameters to account for complex HAR structures, using scattered light intensity distributions at multiple angles and wavelengths to extract accurate profile information despite light decay.
2Measurement precision
If transmission small angle X-ray scattering (T-SAXS) techniques are used to measure critical dimensions of HAR structures, then measurement precision improves, but throughput deteriorates due to low signal strength
Solution Approach 1:
The patent substitutes the X-ray measurement system with an optical measurement system. Instead of using T-SAXS techniques that require X-ray sources and detectors with long measurement times, the system replaces it with optical metrology tools that use visible or near-visible light, enabling much faster measurement speeds and higher throughput while maintaining measurement capability through advanced optical scattering analysis.
Solution Approach 2:
The patent changes the physical parameters of the measurement system by transitioning from X-ray wavelengths to optical wavelengths. This parameter change allows the system to achieve comparable measurement precision for HAR structures but with significantly improved throughput, as optical systems can operate at much higher speeds and with greater signal strength than T-SAXS systems.
3Measurement precision
If a hybrid approach combining OCD and T-SAXS is used, then measurement precision improves, but device complexity increases and throughput deteriorates due to requiring both tools for every sample
Solution Approach 1:
The patent extracts the essential measurement function from the complex hybrid T-SAXS system and isolates it into a standalone optical metrology tool. By taking out the measurement capability that was previously distributed across two different tools (OCD and T-SAXS), the system consolidates it into a single optical system that performs both functions, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent applies universality by designing the optical metrology tool to perform multiple functions that were previously divided between OCD and T-SAXS systems. The single optical system can measure both simple and complex HAR structures with high precision while maintaining high throughput, eliminating the need for separate specialized tools and simplifying the overall measurement infrastructure.
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
This approach enables high-precision, high-throughput measurement of critical dimensions in high-volume production, overcoming the limitations of traditional methods by integrating data from both tools to improve accuracy and efficiency.
Implementation Method 1
transmission small angle X-ray scattering (T-SAXS) techniques
Implementation Method 2
optical metrology tool
Data Source
AI summary
A metrology system is disclosed. In one embodiment, the metrology system includes a controller communicatively coupled to a reference metrology tool and an optical metrology tool, the controller including one or more processors configured to: generate a geometric model for determining a profile of a test HAR structure from metrology data from a reference metrology tool; generate a material model for determining one or more material parameters of a test HAR structure from metrology data from the optical metrology tool; form a composite model from the geometric model and the material model; measure at least one additional test HAR structure with the optical metrology tool; and determine a profile of the at least one additional test HAR structure based on the composite model and metrology data from the optical metrology tool associated with the at least one HAR test structure.