Substrate Processing Liquid Flow Control for Splatter Suppression
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Solution Overview
Problem
Existing substrate processing methods face challenges in preventing processing liquid from splashing obliquely upward during high-speed rotation, leading to contamination due to increased centrifugal force, which results in higher liquid consumption and processing costs.
Innovation Solution
A substrate processing method involving a spin base rotating the substrate vertically, with distinct flow rates for processing liquid supplied to the upper and lower surfaces, where the flow rate on the upper surface is higher than on the lower surface, causing the liquid to splatter obliquely downward and outward, intersecting with lower surface splatter and forcing it into the processing cup, thus preventing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the substrate is rotated at high speed during upper/lower concurrent processing, then the processing liquid can be maintained on the substrate surfaces, but the processing liquid splashes obliquely upward from the peripheral portions, causing contamination and increased liquid consumption
Solution Approach 1:
The processing liquid supply is segmented into separate nozzles for upper surface and lower surface, with independent flow rate control. This allows differential supply rates to be applied to each surface, optimizing liquid distribution and preventing oblique splashing while maintaining reliable processing coverage.
Solution Approach 2:
Different flow rates are applied locally to different surfaces: a first flow rate to the lower surface and a higher second flow rate to the upper surface. This local differentiation in liquid supply quality prevents the processing liquid from splashing obliquely upward while ensuring complete coverage of both surfaces during high-speed rotation.
2Area of stationary object
If the substrate is rotated at high speed, then the processing liquid spreads across the entire substrate surface, but the centrifugal force increases causing the liquid to splash obliquely upward and flow out of the processing cup
Solution Approach 1:
The patent applies different flow rates locally to different surfaces to counteract centrifugal effects. The upper surface receives a higher flow rate that creates sufficient liquid volume and viscosity to resist oblique splashing, while the lower surface receives an optimized flow rate for complete coverage, together preventing contamination during high-speed rotation.
Solution Approach 2:
The flow rate parameter is changed differentially between upper and lower surfaces. By increasing the flow rate to the upper surface relative to the lower surface, the system adjusts liquid distribution parameters to maintain stable liquid films that resist centrifugal-induced oblique splashing while ensuring complete surface coverage.
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 suppresses splashing and contamination, allowing for high-quality substrate processing with reduced processing liquid consumption by ensuring the liquid stays within the processing cup.
Implementation Method 1
the processing liquid supplied onto the upper surface of the substrate undergoes a centrifugal force due to the rotation of the substrate to spread on the upper surface of the substrate from the central portion toward a peripheral portion
Implementation Method 2
causing the liquid to splatter obliquely downward and outward, intersecting with lower surface splatter and forcing it into the processing cup
Data Source
AI summary
A substrate processing method is implemented in a substrate processing apparatus including a substrate holding and rotating unit having a spin base rotatable about a predetermined vertical axis, and a processing cup surrounding the substrate holding and rotating unit and arranged to receive processing liquid splattering from the substrate rotated by the substrate holding and rotating unit, the substrate processing method including a substrate rotating step of rotating the spin base to rotate the substrate about the vertical axis at a predetermined liquid processing speed and, in parallel with the substrate rotating step, a processing liquid supplying step of supplying processing liquid onto the lower surface of the substrate at a predetermined first flow rate and supplying processing liquid onto the upper surface of the substrate at a second flow rate that is higher than the first flow rate.