ICP Faraday Shield Switching for Window Cleaning and Erosion Control
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Solution Overview
Problem
In ICP processing systems, local sputtering damage, uneven window cleaning, and reduced production efficiency due to capacitively coupled voltages and particle contamination during dry etching of nonvolatile materials, along with complex maintenance and reduced cleaning effectiveness of plasma processing chambers, are significant challenges.
Innovation Solution
An ICP processing system is designed with a radio frequency coil having two sub-coils, a faraday shielding device with yttrium oxide coating, and a three-way switch to facilitate the switching of radio frequency power between the coil and the shielding device, allowing for efficient plasma processing and cleaning, reducing erosion and contamination, and simplifying maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a faraday shield is placed between the radio frequency coil and the dielectric window to reduce plasma erosion, then the erosion of chamber walls is reduced, but it becomes very difficult to initiate plasma discharge due to reduced radio frequency electric field strength
Solution Approach 1:
The faraday shield is divided into multiple shielding units arranged in a circular array with slits between them. This segmentation allows the shield to reduce plasma erosion while permitting radio frequency electric field penetration through the slits, thereby maintaining plasma discharge capability.
Solution Approach 2:
The faraday shield structure implements different properties in different regions: the conductive shielding surfaces face the plasma to protect against erosion, while the slits between shielding units allow electric field penetration for plasma initiation. This local differentiation resolves the contradiction between protection and field strength.
2Object-affected harmful factors
If the faraday shield is grounded to reduce plasma erosion, then chamber wall protection is improved, but plasma discharge initiation becomes extremely difficult due to reduced radio frequency electric field strength
Solution Approach 1:
The faraday shield is designed with a floating potential rather than fixed grounding, allowing it to dynamically adjust its electrical state. This dynamic configuration enables the shield to provide protection while maintaining adequate radio frequency electric field strength for plasma initiation.
3Object-generated harmful factors
If cleaning is performed mainly right below the coil to remove particles, then particle removal in the coil area is improved, but areas far from the coil are only slightly cleaned resulting in uneven cleaning
Solution Approach 1:
The faraday shield is excited with radio frequency power during cleaning cycles, creating plasma and associated physical effects that enhance particle removal. This active cleaning mechanism improves cleaning uniformity across the entire dielectric window surface, including areas far from the coil.
4Object-affected harmful factors
If a faraday device is located between the radio frequency coil and the dielectric window to reduce erosion, then chamber protection is improved, but the installation and insulation become very complex and later maintenance becomes increasingly difficult
Solution Approach 1:
The faraday shield is integrated with the dielectric window assembly, combining the protective shielding function with the existing window structure. This merging simplifies installation and maintenance by reducing the number of separate components and eliminating complex insulation requirements between the coil and shield.
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
The system effectively reduces sputtering damage, improves cleaning uniformity, and simplifies maintenance by efficiently coupling radio frequency power to the faraday shielding device, enhancing the cleaning process and reducing downtime, while maintaining the integrity of the dielectric window and chamber.
Implementation Method 1
ICP is usually generated by a coil that is placed outside a plasma processing chamber and is adjacent to a dielectric window, and process gas inside the chamber is ignited to form the plasma
Implementation Method 2
it is inevitable and to some extent undesired that a voltage between different parts of a plasma coil is capacitively coupled into plasma
Implementation Method 3
A faraday shield is used in a plasma processing chamber to reduce the erosion of a chamber material by plasma
Implementation Method 4
the pressure control valve and the vacuum pump maintain the plasma reaction chamber at 1 mtorr to 100 mtorr, and remove excess gas and reaction byproducts in the plasma reaction chamber
Data Source
AI summary
Disclosed in the present application is an inductively coupled plasma treatment system. Said system switches the connection between a radio frequency coil and a faraday shielding device by means of a switch switching radio frequency power. When a radio frequency power supply is connected to the radio frequency coil by means of a matched network, the radio frequency power is coupled into the radio frequency coil to perform plasma treatment process. When a radio frequency power supply is connected to a faraday shielding device by means of a matched network, the radio frequency power is coupled into the faraday shielding device to perform cleaning process on a dielectric window and an inner wall of a plasma treatment cavity.