Substrate Drying via Gas Discharge to Liquid Layer
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Solution Overview
Problem
Substrate drying in substrate processing apparatuses often results in minute droplets remaining due to insufficient centrifugal forces, especially when droplets adhere near the center, leading to development defects.
Innovation Solution
A substrate processing apparatus that holds substrates horizontally and rotates them to form a liquid layer, followed by gas discharge towards the center of the layer, preventing droplet formation and ensuring reliable drying by maintaining the liquid layer's integrity through surface tension without separation into multiple regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If substrates are dried utilizing centrifugal forces by rotating at high speeds, then the majority of rinse liquids can be removed, but minute droplets remain on the substrates especially near the center where smaller centrifugal forces are exerted
Solution Approach 1:
A gas stream is introduced as an intermediary medium to act on the liquid layer. The gas flows along the rotation direction of the substrate and toward the center, creating shear forces that move the liquid layer outward without relying solely on centrifugal force. This intermediary gas flow enables complete removal of minute droplets that centrifugal force alone cannot eliminate.
Solution Approach 2:
The invention uses a gas stream (pneumatic approach) to interact with the liquid layer on the rotating substrate. By controlling the gas flow direction and velocity, the liquid layer is manipulated to move outward and be removed from the substrate surface, particularly effective for removing droplets near the center where centrifugal force is insufficient.
2Productivity
If high rotational speeds are used to remove rinse liquids, then drying efficiency improves, but the liquid layer may separate into multiple regions forming minute droplets
Solution Approach 1:
The invention employs dynamic control of rotational speed and gas flow rate to maintain liquid layer integrity. By adjusting these parameters during the drying process, the liquid layer remains stable and moves as a unified structure outward, preventing separation into droplets while maintaining high drying efficiency.
Solution Approach 2:
The invention changes operational parameters (rotational speed and gas flow rate) to optimize the drying process. By carefully controlling these parameters, the liquid layer maintains its integrity during outward movement, preventing droplet formation while achieving rapid drying.
3Device complexity
If centrifugal force alone is used for drying, then the process is simple, but minute droplets adhere to hydrophilic portions of resist films causing development defects
Solution Approach 1:
A gas stream is introduced as an intermediary to enhance the drying process. The gas flows along the substrate rotation direction and toward the center, creating forces that move the liquid layer outward. This additional intermediary mechanism ensures complete removal of droplets from hydrophilic portions of resist films without significantly complicating the overall process.
Solution Approach 2:
The invention uses pneumatic forces (gas flow) in combination with the existing centrifugal force to achieve complete drying. The gas stream targets the liquid layer specifically, removing residual droplets that cause development defects while maintaining process simplicity through controlled gas injection.
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
The method effectively prevents minute droplets from forming, ensuring reliable substrate drying and preventing development defects caused by residual liquids.
Implementation Method 1
the liquid layer integrally moves outward from the substrate with its annular shape held by surface tension without being separated into a plurality of regions
Implementation Method 2
the rinse liquids on the substrates are shaken off by rotating the substrates at high speeds, so that the substrates are dried
Data Source
AI summary
After a development liquid on a substrate is washed away with a rinse liquid, the rotational speed of the substrate is reduced, so that a liquid layer of the rinse liquid is formed over a top surface of the substrate. Thereafter, the rotational speed of the substrate is increased. The increase in the rotational speed of the substrate causes a centrifugal force to be slightly greater than tension, thereby causing the liquid layer to be held on the substrate with the thickness thereof in its peripheral portion increased and the thickness thereof at the center thereof decreased. Then, gas is discharged toward the center of the liquid layer from a gas supply nozzle, so that a hole is formed at the center of the liquid layer. This causes tension that is balanced with a centrifugal force exerted on the peripheral portion of the liquid layer to disappear. Furthermore, the rotational speed of the substrate is further increased while the gas is discharged. Thus, the liquid layer moves outward from the substrate.