Metrology Apparatus for In-Plane Distortion Measurement
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Solution Overview
Problem
Current wafer alignment models are unable to correct higher order inter-field distortion patterns across multiple dies, which are induced by intra-field stress and are difficult to characterize using existing overlay metrology methods, especially since distortion occurs mainly in the product area between scribelanes.
Innovation Solution
A method for determining in-plane distortion (IPD) across a substrate by obtaining intra-region data indicative of local stress distribution, determining inter-region data for global stress distribution, and using this data to calculate IPD, optionally involving geometric characteristics, material properties, and finite element methods to account for both in-plane and out-of-plane distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional overlay metrology methods are used to measure distortion, then measurement simplicity is maintained, but measurement precision deteriorates because higher order inter-field distortion patterns cannot be characterized
Solution Approach 1:
The patent segments the substrate into multiple regions (first region with patterned features, second region without patterned features) to enable separate measurement of local and global stress distributions. This segmentation allows the metrology system to capture distortion information from different areas independently, improving measurement precision for higher order distortion patterns while managing system complexity through modular measurement regions.
Solution Approach 2:
The patent introduces an intermediary computational model that correlates intra-field stress data with inter-field distortion patterns. This intermediary model acts as a bridge between the measured stress distribution and the resulting distortion, enabling indirect measurement of higher order distortion patterns that cannot be directly observed by conventional metrology methods.
2Manufacturing precision
If intra-field stress is not corrected, then device complexity is reduced, but manufacturing precision deteriorates due to overlay errors in product areas
Solution Approach 1:
The patent applies preliminary correction by determining the stress distribution and calculating distortion patterns before the lithography exposure process. By pre-characterizing the intra-field stress and its impact on inter-field distortion, the system can apply correction factors in advance, improving overlay precision without adding real-time complexity during manufacturing.
Solution Approach 2:
The patent changes the parameters used in alignment models by incorporating stress distribution data and distortion patterns into the conventional overlay correction model. This parameter expansion allows the alignment system to account for higher order distortion effects, improving manufacturing precision while managing device complexity through systematic parameter integration.
Data Source
AI summary
Methods and apparatuses for determining in-plane distortion (IPD) across a substrate having a plurality of patterned regions. A method includes obtaining intra-region data indicative of a local stress distribution across one of the plurality of patterned regions; determining, based on the intra-region data, inter-region data indicative of a global stress distribution across the substrate; and determining, based on the inter-region data, the IPD across the substrate.