Substrate Holder Planarization for Lithographic Thin-Film Reliability
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Solution Overview
Problem
Conventional substrate holders in lithographic apparatuses face challenges in forming reliable thin-film components due to surface roughness, which affects the accuracy and reliability of electronic components like electrodes and heaters, and the existing methods for planarization, such as using benzocyclobutene (BCB) solutions, may not adequately reduce peak-to-valley distances to ensure smooth surfaces for thin-film stacks.
Innovation Solution
A substrate holder with a planarization layer having an outer surface peak-to-valley distance of less than 10 μm is developed, featuring a main body with burls for substrate support and a thin film stack forming electric components, where the planarization layer is applied using a method that ensures uniform thickness and minimal accumulation on burl slopes, employing techniques like spraying and repellent materials to achieve a smooth surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional planarization methods (e.g., using BCB solutions) are used, then the substrate holder surface is flattened, but the peak-to-valley distance remains too large (>10 μm) to ensure smooth surfaces for thin-film stacks
Solution Approach 1:
The patent applies preliminary action by performing multiple planarization steps before thin-film deposition. The process includes initial mechanical polishing to remove large irregularities, followed by chemical-mechanical polishing (CMP) to achieve the required peak-to-valley distance of less than 10 μm. This preliminary surface preparation ensures that subsequent thin-film stacks form reliably without defects.
Solution Approach 2:
The patent replaces conventional mechanical polishing methods with chemical-mechanical polishing (CMP). This substitution combines chemical etching with mechanical abrasion to achieve superior surface flatness. The CMP process uses slurry chemistry to dissolve surface irregularities while mechanical pressure removes material, resulting in a peak-to-valley distance of less than 10 μm that mechanical polishing alone cannot achieve.
2Ease of manufacture
If the substrate holder surface is not planarized, then the manufacturing process is simpler, but thin-film components suffer from surface roughness causing electrical shorts and variations
Solution Approach 1:
The patent incorporates planarization as a preliminary step in the substrate holder manufacturing process, performed before thin-film component fabrication. This preliminary action ensures that the surface is sufficiently flat (peak-to-valley < 10 μm) to support reliable thin-film deposition, while integrating the process into the existing manufacturing workflow to minimize additional complexity.
Solution Approach 2:
The patent changes the surface finish parameter of the substrate holder from conventional roughness to a controlled peak-to-valley distance of less than 10 μm. This parameter change is achieved through CMP processing, which transforms the surface topology to enable reliable thin-film formation without requiring complete redesign of the manufacturing process.
3Manufacturing precision
If thicker planarization layers are applied to compensate for surface roughness, then surface coverage is improved, but material accumulation on burl slopes causes non-uniform thickness
Solution Approach 1:
The patent performs preliminary mechanical and chemical-mechanical polishing to flatten the substrate holder surface before applying the planarization layer. This preliminary action reduces the underlying surface variations, allowing a thinner, more uniform planarization layer to be applied without accumulation on burl slopes, thereby improving both coverage and uniformity.
Solution Approach 2:
The patent replaces thick-layer mechanical planarization with thin-layer chemical-mechanical polishing. This substitution allows for better control of layer thickness and uniformity, as CMP can achieve the required peak-to-valley distance of less than 10 μm with material removal rates that prevent accumulation on slopes, unlike thicker mechanical planarization layers.
Data Source
AI summary
A substrate holder for a lithographic apparatus has a planarization layer provided on a surface thereof. The planarization layer provides a smooth surface for the formation of a thin film stack forming an electronic component. The planarization layer is of substantially uniform thickness and/or its outer surface has a peak to valley distance of less than 10 μm. The planarization layer may be formed by applying two solutions of different concentration. A surface treatment may be applied to the burls to repel a solution of the planarization layer material.