Showerhead Purge Collar Cleaning for Plasma Chamber Residue
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Solution Overview
Problem
Substrate processing systems face challenges in effectively cleaning the plasma chambers, particularly in removing residue buildup on the backside and sides of the showerhead, which is difficult due to parasitic plasma formation.
Innovation Solution
A system comprising a showerhead, a collar, a gas source, and a controller is used to deliver a cleaning gas or inert gas through the collar to areas difficult to clean, leveraging the secondary purge collar to increase the partial pressure of reactive species and extend the lifetime of fluorine radicals, with options for pre-activation of cleaning gas in a remote plasma generator or in-situ activation by RF power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cleaning methods are used in plasma chambers, then the cleaning process is simple, but the cleaning effectiveness is poor due to parasitic plasma formation and residue buildup on showerhead surfaces
Solution Approach 1:
The patent introduces a secondary purge collar as an intermediary component between the showerhead and chamber wall. This collar delivers cleaning gas directly to difficult-to-reach areas, mediating the cleaning process to overcome parasitic plasma formation and residue buildup that conventional methods cannot effectively address.
Solution Approach 2:
The system performs preliminary action by delivering cleaning gas through the secondary purge collar before residue can accumulate significantly, and by pre-positioning the cleaning gas delivery paths to target areas prone to parasitic plasma formation and residue buildup, preventing rather than just treating contamination.
2Area of stationary object
If cleaning gas is delivered through the showerhead only, then the system structure is simple, but the cleaning coverage is insufficient for areas around the showerhead
Solution Approach 1:
The gas delivery system is segmented into two independent paths: the primary showerhead for substrate processing and the secondary purge collar for cleaning. This segmentation allows each component to perform its specific function optimally, with the collar providing targeted cleaning coverage to areas around the showerhead that would otherwise be inaccessible.
Solution Approach 2:
The secondary purge collar adds a radial dimension to gas delivery by positioning cleaning gas outlets around the showerhead periphery. This dimensional addition enables cleaning coverage of lateral and peripheral areas that a top-down showerhead-only approach cannot reach, expanding the effective cleaning volume.
3Quantity of substance
If the cleaning process uses standard purge gas, then the gas supply system is simple, but the partial pressure of reactive species is insufficient to effectively remove residue
Solution Approach 1:
The system changes the chemical parameter of the cleaning gas by using reactive species-rich gases (such as NF3, CF4, or O2) instead of inert purge gas. This parameter change increases the partial pressure of reactive species in the cleaning zone, enabling effective removal of organic and inorganic residue that standard purge gas cannot address.
Solution Approach 2:
The cleaning process uses composite gas chemistry by combining reactive cleaning gas species with inert carrier gases. This composite approach maintains high partial pressure of reactive species for effective cleaning while using inert components to provide stable flow and pressure control, balancing reactivity with system stability.
4Duration of action of moving object
If plasma is generated directly in the chamber for cleaning, then the cleaning power is high, but the lifetime of reactive species is reduced due to rapid recombination
Solution Approach 1:
The secondary purge collar acts as an intermediary delivery mechanism that transports reactive species to the cleaning zone without requiring high-power plasma generation in the chamber. This intermediary approach extends the lifetime of reactive species by delivering them in a controlled manner, avoiding rapid recombination that would occur with direct high-power plasma discharge.
Solution Approach 2:
The system performs preliminary activation of cleaning gas in a remote plasma generator before delivery through the collar. This preliminary action creates reactive species in advance, allowing them to be transported and delivered to target areas where they maintain longer lifetime and effectiveness, rather than generating plasma directly in the chamber where rapid recombination would occur.
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 enhances the cleaning efficiency of the processing chamber by increasing the partial pressure of reactive species and extending the lifetime of fluorine radicals, reducing overall cleaning time and improving the chamber's maintenance.
Implementation Method 1
The plasma generator is external to the processing chamber, receives the cleaning gas from the gas source, and generates plasma
Implementation Method 2
The RF generator supplies RF power. The controller supplies the RF power to the showerhead to generate plasma in the processing chamber
Data Source
AI summary
Systems and methods for cleaning a processing chamber include supplying a pre-activated cleaning gas through a collar surrounding a showerhead stem into the processing chamber to clean the processing chamber. In other embodiments, a cleaning gas is supplied to the collar, and RF power is supplied to the showerhead or to a pedestal to generate plasma in the processing chamber to clean the processing chamber. In still other embodiments, an inert gas is supplied to the collar, a pre-activated cleaning gas is supplied to the showerhead stem, and RF power is supplied to the showerhead or to the pedestal to generate plasma in the processing chamber to clean the processing chamber.