Wafer Coating Valve Sequence for Film Thickness Uniformity
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Solution Overview
Problem
Existing substrate processing technologies face challenges in achieving uniform film thickness due to overshoot and uncontrolled pressure fluctuations during the coating process, particularly in spiral coating methods where viscosity of the processing liquid affects ejection stability.
Innovation Solution
A substrate processing apparatus with a nozzle, force-feeding unit, and liquid feeding pipeline, controlled by a system that manages pressure between valves to prevent backflow and sudden pressure increases, ensuring uniform ejection and reducing overshoot by regulating the opening and closing of valves to maintain stable pressure transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the processing liquid is force-fed to the nozzle using a single valve system, then the device complexity is reduced, but the film thickness uniformity deteriorates due to overshoot and uncontrolled pressure fluctuations
Solution Approach 1:
The liquid feeding pipeline is segmented into multiple sections with two valves (first valve near force-feeding unit, second valve near nozzle) instead of using a single valve system. This segmentation allows independent control of pressure in different sections, enabling suppression of pressure fluctuations and overshoot that cause film thickness non-uniformity.
Solution Approach 2:
The first valve is opened in advance before the second valve to pre-adjust the pressure in the liquid feeding pipeline. By opening the first valve first and controlling the pressure to be higher than the downstream pressure, the system performs preliminary pressure equalization, preventing sudden pressure increases and overshoot when the second valve opens, thereby ensuring uniform film thickness.
2Reliability
If the first valve is opened when downstream pressure is higher, then backflow is suppressed and ejection stability is improved, but the pressure control complexity increases
Solution Approach 1:
The controller monitors pressure conditions in the liquid feeding pipeline and uses feedback control to determine the optimal timing for opening the first valve. By detecting when downstream pressure is higher than upstream pressure, the controller activates the first valve to equalize pressures, ensuring stable ejection while managing control complexity through automated feedback mechanisms.
3Manufacturing precision
If high-viscosity processing liquid is used, then the coating quality is improved, but the pressure fluctuations and overshoot are exacerbated
Solution Approach 1:
The valve opening sequence is dynamically adjusted based on the viscosity characteristics of the processing liquid. For high-viscosity liquids, the system extends the timing for opening the first valve and increases the pressure differential to ensure complete pressure equalization before opening the second valve, thereby suppressing pressure fluctuations and overshoot while maintaining coating quality.
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 solution effectively improves the uniformity of film thickness by suppressing overshoot and stabilizing pressure transitions, enhancing the reproducibility and throughput of the coating process, especially for processing liquids with higher viscosities.
Implementation Method 1
controlling the force-feeding unit to increase the pressure between the first and second valves that has been decreased by the opening of the first valve
Data Source
AI summary
A substrate processing apparatus according to the present disclosure includes: a nozzle that ejects a processing liquid to a wafer; a force-feeding unit that force-feeds the processing liquid to the nozzle side; a liquid feeding pipeline that includes first and second valves and guides the processing liquid from the force-feeding unit to the nozzle; and a controller. The controller is configured to perform opening the first valve in a state where the second valve is closed and a pressure between the first and second valves is higher than a pressure between the force-feeding unit and the first valve, controlling the force-feeding unit to increase the pressure between the first and second valves that has been decreased by the opening of the first valve, and opening the second valve after the pressure between the first and second valves is decreased by the opening of the first valve.