Deformable Substrate Displacement Measurement
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Solution Overview
Problem
Metrology systems in imprint lithography assume rigid templates/masks or substrates, leading to errors in displacement measurements due to deformation caused by forces during alignment, which affects the resolution, uniformity, and reproducibility of imprinted patterns.
Innovation Solution
Moving the measurement point closer to the mask or region of interest minimizes deformation effects, allowing for more accurate determination of rigid body motions and deformation of the substrate, using non-contact sensors to probe sensing marks with patterned structures and combining light beams for interference signals to reduce measurement errors to less than 1 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If displacement measurements are made at peripheral/edge of mask substrate (far from mask), then measurement distance is increased allowing remote sensing, but measurement accuracy deteriorates due to deformation errors in the substrate
Solution Approach 1:
The patent applies preliminary action by pre-positioning sensing marks at multiple locations on the mask substrate before the alignment process begins. These sensing marks are strategically placed to enable measurement of both rigid body motion and deformation components. By having the measurement infrastructure in place beforehand, the system can accurately track mask position even when the substrate deforms during alignment, resolving the contradiction between remote sensing capability and measurement accuracy.
2Device complexity
If rigid body assumption is made for mask substrate, then measurement system complexity is reduced, but measurement reliability deteriorates due to substrate deformation under fluid shear forces
Solution Approach 1:
The patent applies segmentation by dividing the mask substrate motion into distinct components: rigid body motion and deformation. Multiple sensing marks are distributed across the substrate to independently measure different aspects of the motion. By segmenting the measurement function across multiple sensing points, the system can distinguish between overall substrate movement and local deformation, maintaining reliability without excessive complexity.
Solution Approach 2:
The patent uses sensing marks as intermediary elements between the mask substrate and the measurement system. These sensing marks serve as mediators that translate substrate position and deformation into measurable signals. By introducing these intermediary reference features, the system can accurately measure mask position even when the substrate deforms, without requiring complex direct measurement of the mask itself.
3Length of stationary object
If sensing mark is placed far from mask edge, then Abbe offset is increased improving measurement leverage, but deformation effects are amplified increasing measurement error
Solution Approach 1:
The patent applies local quality by placing sensing marks at multiple locations with different distances from the mask edge, rather than uniformly positioning them. This creates local measurement zones with different characteristics - some sensing marks provide high leverage for rigid body motion measurement, while others closer to the mask minimize deformation effects. By optimizing the local measurement quality at different positions, the system achieves accurate overall position measurement despite substrate deformation.
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 improves the fidelity of displacement measurements, mitigates the Abbe offset, and enables precise location and orientation measurement of dimensionally-critical objects by reducing deformation-induced errors, enhancing the accuracy of pattern alignment in imprint lithography.
Implementation Method 1
The non-contact sensor can sense light diffracted from the sensing mark
Implementation Method 2
probing the sensing mark can include combining a first beam of light that diffracts from the sensing mark with a second beam of light to obtain an interference signal
Data Source
AI summary
A method for measuring a position of an object, the method includes probing a sensing mark arranged in a first plane on a substrate to determine the position of the object, a portion of the substrate connecting the sensing mark to the object. An edge of the object can be sufficiently close to an edge of the sensing mark to reduce measurement errors in the position of the object caused by a deformation of the substrate.