DSA Metrology via Intermediate Feature Measurement
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Solution Overview
Problem
Current metrology techniques face challenges in accurately measuring and controlling exposure parameters such as focus and dose during the directed self-assembly (DSA) process, leading to inaccuracies in target feature production and device quality monitoring.
Innovation Solution
Measuring characteristics of intermediate features like guiding lines in the DSA process to derive exposure parameters, which are then used to adjust production parameters, thereby enhancing the accuracy of consecutive target features and improving process control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional metrology techniques are used to measure exposure parameters during DSA process, then measurement capability is provided, but measurement precision and accuracy are insufficient
Solution Approach 1:
The patent creates intermediate features (guiding lines, mandrels, or sacrificial structures) before the final target feature production. These intermediate features are specifically designed to be measurable and to encode exposure parameter information. By performing measurement on these preliminary structures, the system can derive exposure parameters (focus, dose, etch time) without needing to measure the final target features directly, thus preserving measurement precision while managing feature consumption.
Solution Approach 2:
The patent introduces intermediate features as mediators between the exposure process and the measurement system. These intermediate structures (such as guiding lines with specific geometries or sacrificial mandrels) serve as proxies that carry information about the exposure parameters. By measuring these intermediary structures instead of the final target features, the system achieves accurate exposure parameter measurement while protecting the integrity and quantity of the primary target features.
2Manufacturing precision
If exposure parameters are not accurately controlled, then production speed is maintained, but manufacturing precision of target features deteriorates
Solution Approach 1:
The patent implements a feedback loop where intermediate features are measured after the exposure and etching processes. The measured characteristics of these intermediate features (such as dimensions, shapes, or positions) are used to derive exposure parameters (focus, dose, etch time). These derived parameters then feed back to adjust the exposure process for subsequent target feature production. This closed-loop feedback system ensures manufacturing precision is maintained while allowing continuous production, as the feedback adjustment is automated and integrated into the production flow.
Solution Approach 2:
The patent utilizes changes in the physical or chemical parameters of intermediate features (such as dimensional changes, shape variations, or material property modifications) that result from exposure and etching processes. By measuring these parameter changes in the intermediate features, the system can derive the actual exposure parameters used. This approach allows accurate parameter measurement without requiring separate test structures, thereby maintaining both manufacturing precision and production efficiency.
3Reliability
If intermediate features are measured to derive exposure parameters, then process control is improved, but device complexity increases
Solution Approach 1:
The patent designs intermediate features that serve multiple functions: they guide the self-assembly process, enable exposure parameter measurement, and can be integrated into the final device structure. By making these intermediate structures multi-functional, the patent reduces the need for separate dedicated test structures or measurement targets, thereby limiting the increase in device complexity while still achieving improved process control through reliable measurement and feedback.
Data Source
AI summary
Methods and metrology tool modules embodying the methods are provided. Methods comprise measuring characteristics of intermediate features such as guiding lines in a directed self-assembly (DSA) process, deriving exposure parameters from the measured characteristics; and adjusting production parameters for producing consecutive target features according to the derived exposure parameters. The methods and modules enhance the accuracy of the DSA-produced structures and related measurements.