Pre-crushing Contaminating Particles in Lithographic Apparatus
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Solution Overview
Problem
Lithographic apparatuses face issues with focus and overlay errors due to contaminating particles that deform the substrate and patterning device, causing pattern displacement and distortion during the lithography process.
Innovation Solution
The use of a lithographic apparatus with a first and second object holder, where the second object holder deforms contaminating particles more than the first, employing a pre-crushing mechanism to reduce particle size and deformation before the substrate is clamped, thereby improving overlay and focus performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a substrate is clamped between the substrate table and support structure, then the substrate is held stable for lithography, but contaminating particles cause local deformation leading to focus and overlay errors
Solution Approach 1:
The patent applies preliminary action by introducing a pre-crushing mechanism that deforms contaminating particles before the substrate is clamped during lithography. The pre-crusher applies mechanical force to particles on the substrate surface, flattening them and reducing their ability to cause deformation when the substrate is subsequently clamped between the substrate table and support structure. This preliminary treatment prevents the harmful effect of particles while maintaining substrate stability during the actual lithography process.
2Reliability
If the clamping force is increased to improve substrate holding, then substrate stability improves, but particle deformation and focus errors worsen
Solution Approach 1:
The pre-crushing mechanism performs preliminary deformation of particles before the main clamping operation. By flattening particles in advance using the pre-crusher, the system can apply higher clamping forces during lithography without causing excessive particle deformation and focus errors, thus resolving the contradiction between holding stability and pattern placement accuracy.
Solution Approach 2:
The patent converts the harmful effect of particle deformation into a beneficial process by intentionally using controlled mechanical force in the pre-crusher to flatten particles. This controlled deformation before clamping transforms what would otherwise be a harmful effect (particle-induced substrate deformation) into a beneficial outcome (reduced focus and overlay errors during lithography).
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 significantly reduces overlay and focus errors by pre-crushing contaminating particles, ensuring accurate pattern transfer and improved substrate stability during the exposure process.
Implementation Method 1
The lithographic apparatus is arranged to deform a contaminating particle at the holder-facing surface more when the object is held at the second object holder than when the object is held at the first object holder
Data Source
AI summary
A lithographic apparatus includes a first object holder and a second object holder. The first object holder is arranged to hold an object at a holder-facing surface. The object has the holder-facing surface. The second object holder is arranged to hold the object at the holder-facing surface. The lithographic apparatus is arranged to deform a contaminating particle at the holder-facing surface more when the object is held at the second object holder than when the object is held at the first object holder.