Lacquer Planarization via Solvent Atmosphere for Topography Defects
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Solution Overview
Problem
In micro- and nano-fabrication processes, lacquer particles form on the substrate during spraying, leading to irregularities and defects in the lacquer layer, especially on substrates with topographies, causing issues during further processing like exposure to light.
Innovation Solution
A method involving the application of lacquer with a uniform solvent atmosphere to dissolve formed lacquer particles, maintaining sufficient viscosity to prevent the lacquer from flowing, followed by a solvent atmosphere exposure with at least 50 mol% solvent concentration and controlled pressure to remove irregularities and particles, and subsequent heating for hardening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If lacquer is sprayed onto the substrate, then homogeneous coating is achieved, but lacquer particles form on the lacquer layer
Solution Approach 1:
The patent applies preliminary action by exposing the substrate to a solvent atmosphere immediately after lacquer application but before complete drying. This timing allows dissolved particles to be removed while the lacquer is still in a semi-liquid state, preventing particle formation while maintaining coating homogeneity.
Solution Approach 2:
The patent uses an inert solvent atmosphere (such as alcohol or water vapor) to dissolve and remove lacquer particles from the surface. The solvent atmosphere creates a controlled environment that selectively dissolves particles without affecting the overall coating structure, thereby eliminating the harmful particle effect while preserving layer uniformity.
2Stability of the object's composition
If solvent proportion is reduced to prevent lacquer flow, then lacquer stability is improved, but ability to dissolve particles decreases
Solution Approach 1:
The patent applies parameter changes by controlling the solvent proportion within a specific range (5-20% by weight) during the particle removal stage. This optimized solvent concentration provides sufficient dissolving power for particles while maintaining high enough viscosity to prevent unwanted lacquer flow, thus resolving the contradiction between particle removal efficiency and coating stability.
Solution Approach 2:
The patent performs particle dissolution as a preliminary action before the lacquer fully dries and before subsequent processing steps. By removing particles at this intermediate stage when the lacquer is still sufficiently liquid, the method ensures complete particle removal while the lacquer maintains adequate stability to prevent flow during handling and subsequent processing.
3Manufacturing precision
If lacquer is applied on substrates with topographies, then complete coating coverage is achieved, but particle formation increases
Solution Approach 1:
The patent uses a solvent atmosphere that penetrates into the topographic structures of the substrate, dissolving particles on inclined and vertical surfaces. The solvent vapor reaches all areas of the topography uniformly, removing particles from steeply inclined points while the controlled solvent proportion prevents lacquer from flowing off these surfaces, thus maintaining both complete coverage and particle-free surfaces.
Solution Approach 2:
The patent applies preliminary particle removal treatment specifically targeted at topographic surfaces before the lacquer fully sets. This timing allows the solvent to access and dissolve particles on inclined surfaces while the lacquer maintains sufficient viscosity to remain in position, ensuring complete coverage without particle defects even on complex topographies.
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
Ensures a smooth, defect-free lacquer layer on substrates with topographies, preventing local defects and allowing further processing without lacquer flow or particle issues, while maintaining a uniform coating at steeply inclined points.
Implementation Method 1
the coated substrate is exposed to a solvent atmosphere. Since the coated substrate is exposed to the solvent atmosphere the lacquer particles which have been formed on the substrate are dissolved
Implementation Method 2
the solvent proportion of the applied lacquer must be kept in a range in which the viscosity of the applied lacquer is sufficiently high to ensure that the lacquer no longer flows
Implementation Method 3
The coated substrate can be exposed to a vacuum in order to reduce the solvent proportion of the lacquer applied to the substrate. In this way a part of the volatile solvent evaporates, and so the viscosity of the lacquer is increased
Implementation Method 4
After it has been exposed to the solvent atmosphere, the coated substrate is preferably heated, whereby the applied lacquer is subjected to a soft bake. The soft bake reduces the solvent proportion of the lacquer so much that the lacquer is fully hardened
Data Source
AI summary
The disclosure relates to a method for coating a substrate with a lacquer. First, the lacquer is uniformly applied to the substrate. Then, the solvent proportion of the lacquer applied to the substrate is reduced, and the coated substrate is exposed to a solvent atmosphere. In some embodiments, the lacquer is heated. The invention also relates to a device for planarising a lacquer layer.