Thermal Object Positioner for Lithographic Substrate Flatness
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Solution Overview
Problem
Lithographic processes face challenges in maintaining substrate flatness due to deformations caused by processing steps like resist layer application and etching, which affect pattern accuracy and lead to overlay errors.
Innovation Solution
An object positioner with a thermal device that applies a temperature difference to the substrate, causing uniform or non-uniform thermal expansion to correct its shape, counteracting existing deformations and improving flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the substrate is clamped onto an object support with a locally varying clamping force to flatten the substrate, then the substrate flatness is improved, but the device complexity increases and modifications to the object support are required
Solution Approach 1:
The patent replaces the mechanical clamping system with a thermal field-based solution. Instead of using physical clamps to force the substrate flat, a thermal device applies controlled temperature differences to the substrate, utilizing thermal expansion to achieve the desired flatness. This eliminates the need for mechanical modifications to the object support.
Solution Approach 2:
The patent changes the physical state parameter of the substrate from mechanical constraint to thermal control. By adjusting the temperature distribution across the substrate, the system exploits thermal expansion coefficients to correct deformations. The thermal device creates specific temperature gradients that cause the substrate to expand or contract in a controlled manner, achieving flatness without mechanical force.
2Shape
If the substrate is clamped onto an object support with a locally varying clamping force, then the substrate flatness is improved, but the overlay error increases due to deformation in the plane of the substrate
Solution Approach 1:
The patent replaces mechanical clamping with thermal control to eliminate the source of overlay errors. Mechanical clamping induces stresses and deformations in the substrate plane that cause overlay misalignment. The thermal method applies uniform pressure through thermal expansion while creating controlled temperature gradients that correct shape without introducing mechanical stresses that would affect overlay accuracy.
3Shape
If the substrate is clamped onto an object support, then the substrate flatness is improved to some extent, but the deformation in the direction perpendicular to the plane is not solved and may be enhanced
Solution Approach 1:
The patent substitutes mechanical clamping with thermal field control. The thermal device applies controlled temperature differences that cause the substrate to expand or contract uniformly, correcting flatness while maintaining stability. The thermal method avoids the mechanical stresses and instability issues associated with clamping, providing a more stable and controllable correction process.
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
The solution effectively reduces substrate deformations, enhancing pattern accuracy and minimizing overlay errors by thermally adjusting the substrate's shape to match the desired flatness.
Implementation Method 1
a thermal device, which thermal device is configured to provide at least a part of the object with a first object temperature, which first object temperature differs from the support surface temperature by a first predetermined temperature difference
Data Source
AI summary
The invention provides an object positioner comprising:—an object support having an object support surface which is configured to engage at least a part of an object, said object support surface having a support surface temperature,—a thermal device, which thermal device is configured to provide at least a part of the object with a first object temperature, which first object temperature differs from the support surface temperature by a first predetermined temperature difference.