Absolute Overlay Measurement Across DUV and EUV Layers
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Solution Overview
Problem
The use of deep ultraviolet (DUV) and extreme ultraviolet (EUV) equipment in semiconductor manufacturing leads to overlay misalignment due to differences in wafer stage, reticle, slit, and optical system, making it difficult to correct high-order components like the K13 component in the overlay.
Innovation Solution
An overlay measurement method that performs absolute measurements on overlay marks using both DUV and EUV equipment, feeding back the results to correct the K13 component, allowing for accurate alignment and minimizing high-order overlay errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If DUV and EUV equipment are used together for multi-layer exposure, then productivity and manufacturing capability are improved, but overlay misalignment and measurement precision deteriorate due to differences in wafer stage, reticle, slit, and optical system
Solution Approach 1:
The patent introduces a coordinate conversion module as an intermediary that transforms overlay mark position information between different coordinate systems (DUV equipment coordinate system and EUV equipment coordinate system). This mediator enables accurate overlay measurement by converting positions to a common reference frame, resolving the precision loss caused by equipment differences.
Solution Approach 2:
The patent implements a feedback mechanism where overlay mark position information is measured, converted between coordinate systems, and fed back to correct overlay errors. The measurement results are used to adjust and improve subsequent exposure processes, enabling continuous refinement of overlay alignment precision across DUV and EUV multi-layer manufacturing.
2Device complexity
If relative measurement methods are used for overlay marks, then device complexity is reduced, but the ability to correct high-order overlay components like K13 is insufficient
Solution Approach 1:
The patent transitions from two-dimensional relative measurement to three-dimensional absolute measurement by incorporating the wafer stage position (obtained through encoder) as a third dimension. This enables the determination of overlay mark positions in absolute coordinates, providing sufficient information to correct high-order overlay components like K13 while maintaining manageable device complexity.
3Measurement precision
If absolute coordinate measurement is implemented for overlay marks, then overlay correction precision is improved, but information loss occurs when converting between DUV and EUV equipment coordinate systems
Solution Approach 1:
The patent replaces mechanical coordinate system transformations with mathematical coordinate conversion. By using encoder data to obtain wafer stage position and applying mathematical transformation formulas, the system converts overlay mark positions between DUV and EUV coordinate systems without physical measurement errors or information loss, maintaining high precision throughout the conversion process.
Data Source
AI summary
An overlay measurement method for accurately measuring and correcting an overlay in an environment in which a deep ultraviolet (DUV) apparatus and an extreme ultraviolet (EUV) apparatus are used together, a semiconductor device manufacturing method using the overlay measurement method, and an overlay measurement apparatus are provided. The overlay measurement method includes performing an absolute measurement of a position of an overlay mark of at least one of a plurality of layers, based on a fixed position, wherein an exposure process is performed on a first layer of the plurality of layers by using the DUV apparatus, and an exposure process is performed on an nth layer of the plurality of layers, which is an uppermost layer of the plurality of layers, by using the EUV apparatus.