Supercritical Drying Valve Control for Semiconductor Substrate
Solution Overview
Problem
The existing drying methods for semiconductor wafers using a processing fluid in a supercritical state require a long time due to constant valve opening degrees during decompression from high pressure to atmospheric pressure.
Innovation Solution
A substrate processing apparatus with a controller that adjusts the valve opening degree of the discharge valve to maintain an equal decompression rate from a first pressure to a second pressure and then to a third pressure, allowing for efficient decompression to atmospheric pressure, utilizing a variable valve and an ejector for forced exhaust.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a constant valve opening degree is used during decompression from high pressure to atmospheric pressure, then the decompression process is simple to control, but the drying time becomes excessively long
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant valve opening degree to a dynamic variable valve opening degree that changes during the decompression process. The valve opening degree is adjusted in multiple stages: initially kept constant to maintain supercritical state, then gradually increased to accelerate decompression while preventing pattern collapse, and finally controlled to maintain equal decompression rate. This dynamic adjustment resolves the contradiction by optimizing both control simplicity and drying time.
Solution Approach 2:
The patent implements parameter changes by modifying the valve opening degree parameter during the decompression process. The controller adjusts the valve opening degree based on pressure conditions: maintaining it constant during the supercritical phase, then varying it to achieve different decompression rates at different pressure levels. This parameter change strategy enables the system to achieve both operational simplicity and reduced drying time.
2Productivity
If the decompression rate is increased to shorten drying time, then productivity improves, but pattern collapse and particle generation occur
Solution Approach 1:
The patent applies segmentation by dividing the decompression process into multiple distinct stages with different valve opening degree control strategies. The first stage maintains constant valve opening to preserve supercritical state and prevent pattern collapse. The second stage gradually increases valve opening to accelerate decompression. The third stage controls the valve to maintain equal decompression rate. This segmentation allows the system to achieve high productivity while maintaining pattern stability at each stage.
Solution Approach 2:
The patent implements beforehand cushioning by initially maintaining a constant valve opening degree to keep the processing fluid in a supercritical state, which acts as a cushioning mechanism to prevent pattern collapse. This preparatory phase ensures that the wafer surface is protected before the accelerated decompression phase begins, thus preventing particle generation while enabling subsequent high-speed drying.
3Loss of time
If a variable valve opening degree is used to optimize decompression rate, then drying time is reduced, but device complexity increases
Solution Approach 1:
The patent applies feedback by implementing a controller that monitors the pressure conditions inside the processing chamber and automatically adjusts the valve opening degree accordingly. The controller receives pressure information and modulates the valve to achieve the desired decompression profile: maintaining supercritical state initially, then accelerating decompression, and finally maintaining equal decompression rate. This feedback mechanism reduces drying time while managing device complexity through automated control.
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 shortens the overall drying time while maintaining stability and preventing pattern collapse, allowing for efficient processing with reduced risk of particle generation.
Implementation Method 1
a drying process of drying a substrate using a processing fluid in a supercritical state
Implementation Method 2
When the inside of the processing container is decompressed from a first pressure at which the processing liquid is in a supercritical state to an atmospheric pressure
Data Source
AI summary
Provided is a substrate processing apparatus in which a drying process of drying a substrate using a processing fluid in a supercritical state is performed. The substrate processing apparatus includes: a processing container in which the drying process is performed; a discharge valve provided in a discharge flow path that discharges the processing fluid from the processing container; and a controller configured to control the discharge valve. When the inside of the processing container is decompressed from a first pressure at which the processing fluid is in the supercritical state to an atmospheric pressure, through a second pressure than the first pressure and a third pressure lower than the second pressure, the controller controls a valve opening degree of the discharge valve so that the decompression rate is equal from the second pressure to the third pressure.