Lithography Burls with Non-Flat Topography to Reduce Friction
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Solution Overview
Problem
In lithographic apparatuses, the interface between support structures and objects leads to wear and static friction, causing distortions and overlay errors due to unwanted radiation and heat damage from non-EUV radiation sources, which existing technologies fail to adequately address.
Innovation Solution
The implementation of a support structure with a plurality of burls having non-flat top surfaces to reduce contact area and friction, thereby minimizing distortions and errors, by altering the topography of the burls to decrease the contact surface area between the substrate and the support structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flat support structure is used to support the substrate, then the substrate is well-supported, but the contact area increases causing increased static friction and distortions
Solution Approach 1:
The support structure transitions from a uniformly flat surface to one with localized non-flat regions (burls). These burls create specific contact points rather than continuous contact, reducing the overall contact area while maintaining support functionality. This local modification of surface quality reduces static friction and Van der Waals forces without compromising substrate support stability.
Solution Approach 2:
The invention introduces curved or non-flat surface features (burls) on the support structure instead of a flat surface. These curved features reduce the contact area between the substrate and support structure, minimizing adhesive forces and static friction while maintaining mechanical support.
2Manufacturing precision
If EUV radiation source is used to reduce minimum printable size, then resolution improves, but unwanted IR radiation causes heat damage to components
Solution Approach 1:
The invention extracts or removes the harmful IR radiation component from the radiation spectrum while retaining the useful EUV radiation. This is achieved through spectral filtering that separates the desired EUV wavelengths from the harmful IR wavelengths, eliminating heat damage to components while preserving resolution capabilities.
Solution Approach 2:
The invention converts the harmful IR radiation into a beneficial situation by using spectral filtering to remove it. The filtering process transforms the problematic multi-wavelength radiation into a purified EUV beam, turning the original harmful situation into a beneficial one where only the desired radiation remains.
3Manufacturing precision
If spectral purity filter is used to increase EUV proportion, then radiation quality improves, but device complexity increases
Solution Approach 1:
The support structure with non-flat burls serves multiple functions: it provides mechanical support for the substrate, reduces contact area to minimize friction and distortions, and maintains compatibility with the vacuum environment. This multi-functionality reduces the need for additional separate components, thereby managing device complexity while achieving the desired radiation spectral purity.
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 solution effectively reduces the coefficient of static friction and minimizes distortions, enhancing the flatness and accuracy of substrates during the lithography process, while maintaining a vacuum environment to prevent heat damage from IR radiation.
Implementation Method 1
static friction and/or Van der Waals forces between the object and the support structure may cause local distortions
Implementation Method 2
static friction and/or Van der Waals forces between the object and the support structure may cause local distortions
Implementation Method 3
unwanted IR radiation can cause heat damage to components within the system
Implementation Method 4
unwanted IR radiation can cause heat damage to components within the system
Data Source
AI summary
Various burl designs for holding an object in a lithographic apparatus are described. A lithographic apparatus includes an illumination system, a first support structure, a second support structure, and a projection system. The illumination system is designed to receive radiation and to direct the radiation towards a patterning device that forms patterned radiation. The first support structure is designed to support the patterning device on the first support structure. The second support structure has a plurality of burls and is designed to support the substrate on the plurality of burls. A topography of a top surface of each of the plurality of burls is not substantially flat, such that a contact area between the substrate and each of the plurality of burls is reduced. The projection system is designed to receive the patterned radiation and to direct the patterned radiation towards the substrate.