Pumping Exhaust Flow Control for Effluent Buildup Cleaning
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Solution Overview
Problem
Substrate processing systems face issues with solid effluent buildup in exhaust lines due to reactive process gas combinations, which leads to reduced exhaust flow rates and increased defects, making existing methods like heating inert dilution gas ineffective.
Innovation Solution
A method involving a higher flow rate of inert dilution gas during substrate treatment and a lower flow rate during cleaning, using cleaning plasma to etch solid effluent in the exhaust lines, and disabling the resistive heater during the cleaning process to prevent combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If inert dilution gas is heated and exhaust lines are heated to prevent condensation, then effluent buildup is reduced, but reaction rates increase causing combustion risk
Solution Approach 1:
The patent applies dynamics by making the heater operation dynamic rather than static. The resistive heater is enabled during substrate treatment to prevent effluent condensation and buildup, but is disabled during cleaning processes when fluorinated process gases are used. This dynamic control of heating based on process stage eliminates the combustion risk while maintaining effluent prevention during deposition.
Solution Approach 2:
The patent applies parameter changes by modifying the operational state of the heater based on process conditions. The heating parameter is changed from active to inactive depending on whether the system is in treatment mode or cleaning mode. This parameter change resolves the contradiction by preventing effluent buildup during treatment while avoiding combustion during cleaning with fluorinated gases.
2Object-generated harmful factors
If high flow rate of inert dilution gas is used during substrate treatment, then effluent buildup is prevented, but cleaning effectiveness is reduced
Solution Approach 1:
The patent applies dynamics by changing the inert dilution gas flow rate based on process stage. During substrate treatment, a high flow rate is maintained to prevent effluent buildup. During cleaning processes, the flow rate is reduced to allow cleaning plasma to effectively reach and remove effluent deposits from exhaust lines. This dynamic flow rate adjustment resolves the contradiction between prevention and cleaning effectiveness.
Solution Approach 2:
The patent applies periodic action by alternating between high flow rate during treatment and low flow rate during cleaning. This periodic modification of gas flow allows the system to optimize for effluent prevention during deposition while enabling effective cleaning during designated cleaning cycles, resolving the contradiction through time-based separation of functions.
3Temperature
If resistive heater is enabled continuously, then effluent condensation is prevented, but combustion of process gases occurs
Solution Approach 1:
The patent applies dynamics by making heater operation conditional rather than continuous. The resistive heater is enabled only during substrate treatment when effluent prevention is needed, and is disabled during cleaning processes when fluorinated process gases are present. This dynamic control maintains necessary temperature to prevent condensation during treatment while avoiding combustion during cleaning.
Solution Approach 2:
The patent applies parameter changes by modifying the heater's operational state based on process conditions. The temperature parameter is actively controlled to be elevated during treatment but reduced during cleaning. This parameter change resolves the contradiction by maintaining temperature only when needed for effluent prevention while avoiding temperature-induced combustion during cleaning operations.
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 effectively reduces effluent buildup by increasing the residence time and partial pressure of activated fluorine gas species, allowing for efficient cleaning and preventing blockages in the exhaust system.
Implementation Method 1
supplying cleaning plasma including cleaning gas in the processing chamber during a cleaning process
Implementation Method 2
using cleaning plasma to etch solid effluent in the exhaust lines
Implementation Method 3
supplying the inert dilution gas at a second flow rate that is less than the first flow rate to the pumping exhaust system during the cleaning process
Data Source
AI summary
A method for reducing effluent buildup in a pumping exhaust system of a substrate processing system includes, during a substrate treatment process, arranging a substrate on a substrate support in a processing chamber; supplying one or more process gases to the processing chamber; supplying an inert dilution gas at a first flow rate to the pumping exhaust system; performing the substrate treatment process on the substrate in the processing chamber; evacuating reactants from the processing chamber using the pumping exhaust system. The method includes, after the substrate treatment process, supplying cleaning plasma including cleaning gas in the processing chamber during a cleaning process; and supplying the inert dilution gas at a second flow rate that is less than the first flow rate to the pumping exhaust system during the cleaning process.