Combined Electron Beam and Scatterometry Overlay Targets
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Solution Overview
Problem
Current semiconductor manufacturing processes face challenges in accurately measuring overlay errors between successive patterned layers, which affects the alignment and precision of semiconductor devices, and existing methods require improved target designs and measurement techniques to handle increasingly complex devices.
Innovation Solution
The development of a target design that combines electron beam overlay and scatterometry overlay measurements, featuring periodic structures on multiple layers with specific dimensions and orientations, allowing for simultaneous measurement using both technologies, thereby increasing measurement accuracy and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate target designs are used for electron beam overlay and scatterometry overlay measurements, then each measurement method can be optimized for its specific requirements, but measurement time increases and productivity decreases due to sequential measurements
Solution Approach 1:
The patent combines electron beam overlay and scatterometry overlay measurements into a single integrated target structure. The target includes first and second periodic structures with different pitch ratios that can simultaneously accommodate both electron beam diffraction patterns and optical scatterometry measurements, eliminating the need for separate sequential measurements and improving productivity while maintaining measurement precision
Solution Approach 2:
The integrated target design serves multiple functions: it provides periodic structures for electron beam diffraction-based overlay measurement and simultaneously provides periodic structures for optical scatterometry measurement. This multi-functional target eliminates the need for separate specialized targets for each measurement method
2Measurement precision
If denser sampling is implemented to improve overlay measurement accuracy, then measurement precision improves, but the area required for measurement increases
Solution Approach 1:
The patent utilizes the vertical stacking dimension by forming periodic structures on different layers (first periodic structure and second periodic structure at different heights). This allows denser sampling of overlay information in the vertical dimension rather than requiring expanded horizontal area, achieving improved measurement precision within a compact footprint
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 combined target design enhances measurement accuracy and reduces measurement time by enabling denser sampling and increased information content per area, improving the ability to correct overlay errors and align semiconductor devices more precisely.
Implementation Method 1
Scatterometry utilizes interference between electromagnetic (EM) waves scattered by periodic overlay marks (targets with periodic structures) printed at different layers to deduce the relative displacement of the layers
Implementation Method 2
Scatterometry utilizes interference between electromagnetic (EM) waves scattered by periodic overlay marks
Implementation Method 3
In both cases a control on amplitudes and phases of the diffraction orders of the scattered electromagnetic waves may provide an effect on accuracy and precision of overlay measurement
Data Source
AI summary
Combined electron beam overlay and scatterometry overlay targets include first and second periodic structures with gratings. Gratings in the second periodic structure can be positioned under the gratings of the first periodic structure or can be positioned between the gratings of the first periodic structure. These overlay targets can be used in semiconductor manufacturing.