Substrate Spin Drying with Solvent Vapor Atmosphere
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Solution Overview
Problem
The challenge in substrate processing is the collapse of fine, high-aspect-ratio patterns on substrates due to nonuniform liquid surface heights and unbalanced surface tension during the spin drying process, which can lead to defects and pattern distortion.
Innovation Solution
A substrate processing method involving the formation of a uniform organic solvent liquid film, followed by high-speed rotation in an organic solvent vapor atmosphere to maintain a thin film and prevent evaporation, ensuring uniform thickness and controlled removal of the solvent to prevent pattern collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the substrate is rotated at high speed in the spin drying step, then the rinsing liquid is removed efficiently, but the liquid surface height becomes nonuniform and pattern collapse occurs
Solution Approach 1:
The method applies preliminary action by supplying organic solvent to the substrate before the high-speed spin drying step. This pre-treatment ensures that the pattern is already coated with organic solvent, which prevents collapse during the subsequent high-speed rotation by providing uniform surface tension support from the beginning of the drying process.
Solution Approach 2:
The method changes the physical-chemical parameters by replacing the rinsing liquid with organic solvent that has different surface tension characteristics. The organic solvent maintains uniform liquid surface height at high rotation speeds due to its lower surface tension, preventing the nonuniformity that causes pattern collapse while still enabling efficient drying.
2Manufacturing precision
If organic solvent is supplied to replace rinsing liquid, then pattern collapse is prevented, but liquid surface height becomes nonuniform due to evaporation
Solution Approach 1:
The organic solvent is supplied in advance before high-speed rotation begins. This preliminary coating ensures uniform distribution of the solvent across the pattern surface before centrifugal forces and evaporation set in, establishing a stable baseline for uniform liquid surface height throughout the drying process.
Solution Approach 2:
The method maintains continuous presence of organic solvent on the pattern surface throughout the spin drying process. By ensuring the solvent remains on the surface continuously during high-speed rotation, the uniform surface tension is maintained throughout, preventing both pattern collapse and liquid surface nonuniformity.
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 method effectively prevents pattern collapse by maintaining a uniform liquid surface height and balanced surface tension, allowing for efficient and reliable drying of substrates while preserving pattern integrity.
Implementation Method 1
The surface tension of the liquid acts on a contact position between the liquid surface and the pattern
Implementation Method 2
an impulse that acts on each structural element becomes large when an unbalanced state of the surface tension acting on the structural element P1 continues for a long time
Implementation Method 3
an opportunity to come into contact with fresh air increases, and the evaporation speed of the organic solvent liquid becomes higher in proportion to an approach to the peripheral edge of the front surface of the substrate W
Data Source
AI summary
A substrate processing method includes a liquid film forming step of forming a liquid film of an organic solvent with which a whole area of an upper surface of a substrate is covered in order to replace a processing liquid existing on the upper surface with an organic solvent liquid, a thin film holding step of thinning the liquid film of the organic solvent by rotating the substrate at a first high rotational speed while keeping surroundings of the whole area of the upper surface in an atmosphere of an organic solvent vapor and holding a resulting thin film of the organic solvent on the upper surface, and a thin-film removing step of removing the thin film from the upper surface after the thin film holding step, and the thin-film removing step includes a high-speed rotation step of rotating the substrate at a second high rotational speed.