RF Plasma Cycling for Particle Removal in Substrate Processing
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Solution Overview
Problem
Current substrate processing systems are inefficient in removing particles from the processing chamber, with purge gas cycling taking a long time and not effectively reducing particle levels due to electrostatic forces causing particles to stick and congregate on surfaces.
Innovation Solution
The method involves generating RF plasma and supplying purge gas in cycles after the substrate is removed, with RF plasma being turned on and off, and purge gas being supplied during the off periods to dislodge and remove particles electrostatically stuck on surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If purge gas is cycled on and off after substrate removal, then particles can be removed from the processing chamber, but the process takes a relatively long time (24 hours) and may not reduce particles to an acceptable level
Solution Approach 1:
The patent applies periodic action by cycling RF plasma on and off in repeated cycles (N cycles) during particle removal. The RF plasma is turned on for a first period and off for a second period during each cycle, with purge gas supplied during at least part of each cycle. This periodic plasma generation enhances particle dislodgement effectiveness compared to continuous or simple gas cycling, reducing both time and improving particle removal effectiveness.
Solution Approach 2:
The patent changes physical parameters by introducing RF plasma generation during the particle removal process. The RF plasma alters the state of the gas in the chamber, creating ionized conditions that enhance particle dislodgement from chamber surfaces. This parameter change (from neutral gas to plasma state) significantly improves particle removal effectiveness and reduces the time required compared to pure gas cycling.
2Loss of time
If RF plasma is generated in cycles with purge gas, then particle removal time is reduced to 2-3 hours, but the system complexity increases due to RF plasma control requirements
Solution Approach 1:
The RF plasma generation system serves multiple functions: it activates chemical reactions during substrate processing, and it dislodges particles from chamber surfaces during particle removal. By using the same RF plasma generation capability for both film deposition and particle removal, the system avoids adding separate specialized equipment, thereby reducing overall system complexity while achieving faster particle removal.
Solution Approach 2:
The existing RF plasma generation infrastructure in the substrate processing system is utilized for particle removal without requiring entirely new equipment. The controller that manages substrate processing also manages the RF plasma cycling for particle removal, allowing the system to serve itself across different operational modes and minimizing additional control complexity.
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 time required to lower particle counts in the processing chamber, achieving better results in 2-3 hours compared to 24-48 hours of gas-only cycling, thereby reducing post-maintenance conditioning time.
Implementation Method 1
generating RF plasma in the processing chamber during N cycles, where N is an integer greater than one, wherein the RF plasma is on for a first period and off for a second period during each of the N cycles
Implementation Method 2
purge gas being supplied during the off periods to dislodge and remove particles electrostatically stuck on surfaces
Data Source
AI summary
Systems and methods for operating a substrate processing system include processing a substrate arranged on a substrate support in a processing chamber. At least one of precursor gas and/or reactive gas is supplied during the processing. The substrate is removed from the processing chamber. Carrier gas and purge gas are selectively supplied to the processing chamber. RF plasma is generated in the processing chamber during N cycles, where N is an integer greater than one. The RF plasma is on for a first period and off for a second period during each of the N cycles. The purge gas is supplied during at least part of each of the N cycles.