Semiconductor Purge Sequence Using Heated Gate Valve
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Solution Overview
Problem
The generation of byproducts due to contact between deposition and cleaning gases in plasma CVD processes leads to contamination and reduced productivity, requiring lengthy purge and evacuation operations.
Innovation Solution
Purge and evacuation operations are optimized by performing them only between deposition and cleaning processes, with the gate valve opening under higher transfer chamber pressure, continuous inert gas supply, and maintaining the gate valve and passage at elevated temperatures to inhibit gas adsorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If purge and evacuation operations are performed repeatedly between deposition and cleaning processes, then contamination from gas contact is reduced, but operation time increases and productivity decreases
Solution Approach 1:
The gate valve and passage are heated to elevated temperatures before gas introduction to prevent adsorption of deposition and cleaning gases. This preliminary thermal preparation eliminates the need for repeated purge operations, reducing operation time while maintaining purity.
Solution Approach 2:
The temperature of the gate valve and passage is changed to an elevated state during the process. This parameter change prevents gas adsorption and subsequent byproduct formation, allowing single-stage purification instead of repeated purge-evacuation cycles.
2Loss of time
If the gate valve and passage are heated to elevated temperatures, then gas adsorption is inhibited and purge time is reduced, but energy consumption increases
Solution Approach 1:
The gate valve and passage are heated to elevated temperatures and maintained at this state throughout the deposition and cleaning processes. This continuous thermal state prevents gas adsorption repeatedly, eliminating the need for repeated heating cycles and reducing total energy consumption despite the continuous heating requirement.
3Productivity
If deposition and cleaning gases are introduced without purging, then operation time is reduced, but byproducts are generated causing contamination
Solution Approach 1:
The gate valve and passage are maintained at elevated temperatures to create an environment where deposition and cleaning gases do not adsorb or react. This thermal inert environment allows direct introduction of gases without purging, preventing byproduct formation while maintaining high operation speed.
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 reduces particle deposits on wafers, enables high-speed purge and evacuation, and maintains purity, resulting in increased productivity and stable operation without the need for frequent ex-situ cleaning.
Implementation Method 1
maintaining the gate valve and passage at elevated temperatures to inhibit gas adsorption
Implementation Method 2
supplying an inert gas into the reaction chamber continuously from the transfer chamber when the gate valve is open
Implementation Method 3
the pressure of the transfer chamber is controlled to be higher than that of the reaction chamber before and while the gate valve is opened
Implementation Method 4
high-frequency power is applied to generate plasma and thereby form various types of thin films on wafers
Implementation Method 5
a method to use the same plasma excitation apparatus used for deposition also for activation of cleaning gas (in-situ plasma cleaning)
Data Source
AI summary
A method of processing semiconductor substrates includes: depositing a film on a substrate in a reaction chamber; evacuating the reaction chamber without purging the reaction chamber; opening a gate valve and replacing the substrate with a next substrate via the transfer chamber wherein the pressure of the transfer chamber is controlled to be higher than that of the reaction chamber before and while the gate valve is opened; repeating the above steps and removing the substrate from the reaction chamber; and purging and evacuating the reaction chamber, and cleaning the reaction chamber with a cleaning gas.