Substrate Drying Control for Uniform IPA Evaporation
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Solution Overview
Problem
Current substrate drying techniques using drying liquids often result in defects such as pattern collapse, particle adhesion, and cleaning residues due to uneven removal of the drying liquid, particularly when the IPA liquid contact point moves from the center to the peripheral edge of the substrate, leading to increased IPA liquid film width and uneven drying.
Innovation Solution
A substrate processing apparatus and method that control the distance of the drying liquid flow line from the liquid contact point to the edge of the substrate, keeping it within a preset upper limit distance, and maintain constant centrifugal acceleration along the movement direction of the liquid contact point, ensuring uniform IPA distribution and evaporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the drying liquid supply position is moved from center to peripheral edge, then the drying liquid can sweep away the liquid film, but the liquid film width increases and causes uneven drying
Solution Approach 1:
The substrate rotation speed is dynamically adjusted during the drying process. The rotation speed is increased when the drying liquid supply position is at the center and decreased when at the peripheral edge, maintaining constant centrifugal acceleration. This dynamic adjustment prevents excessive liquid film width accumulation at the periphery while ensuring effective liquid film removal, resolving the contradiction between drying uniformity and liquid film width control.
2Productivity
If the substrate rotation speed is increased to improve drying efficiency, then drying speed increases, but centrifugal acceleration varies causing uneven liquid distribution
Solution Approach 1:
The invention changes the rotation speed parameter dynamically during the drying process rather than maintaining a constant speed. By adjusting the rotation speed according to the drying liquid supply position, the centrifugal acceleration is kept constant, ensuring uniform liquid distribution while maintaining high drying efficiency. This parameter change strategy resolves the contradiction between drying speed and liquid distribution uniformity.
3Productivity
If the drying liquid flow rate is increased to improve drying efficiency, then drying speed increases, but liquid residues and defects increase
Solution Approach 1:
The invention implements a feedback control mechanism where the drying liquid flow rate is adjusted based on the substrate rotation speed and supply position. The control device monitors the drying process conditions and dynamically adjusts the flow rate to maintain optimal drying efficiency while preventing liquid residue formation. This feedback control resolves the contradiction between drying efficiency and liquid residue reduction.
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 approach significantly reduces the occurrence of defects by maintaining a controlled IPA flow rate and centrifugal acceleration, resulting in a more uniform drying process and minimizing IPA residues on the substrate surface.
Implementation Method 1
a centrifugal acceleration acting on the drying liquid at a liquid contact point becomes constant along a movement direction of the liquid contact point
Implementation Method 2
a drying liquid supply nozzle which supplies a drying liquid that dries the substrate to a surface of the substrate rotating after processed with a processing liquid
Data Source
AI summary
A substrate processing apparatus includes a substrate holding device, a rotation mechanism, a drying liquid supply nozzle, a movement mechanism, a flow rate control mechanism, and a control device including circuitry which controls one or more of the rotation mechanism, movement mechanism and flow rate control mechanism such that the drying liquid forms a drying liquid flow line having distance (L) equal to or less than preset upper limit distance (M), where when a liquid contact point is position at which the drying liquid discharged from the nozzle reaches the substrate, the flow line is formed when the liquid contact point is moved from a center portion of the substrate toward a peripheral edge portion of the substrate, and the distance (L) of the flow line is measured from center of the liquid contact point to an edge of the flow line on a rotation center side of the substrate.