Plasma Chamber Liner Slots for Azimuthal RF Current Symmetry
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Solution Overview
Problem
Traditional plasma processing apparatuses experience azimuthal asymmetric perturbation in RF current flow due to the design of the chamber liner, leading to non-uniform etch or deposition rates, as the RF return current concentrates at the lateral edges of slots, causing electrical skews and defective plasma processes.
Innovation Solution
A liner assembly with three or more symmetrically arranged slots is introduced to provide an axial symmetric RF current path, ensuring balanced RF current flow and compensating for density concentrations, thereby enhancing the uniformity of electromagnetic fields and plasma processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional chamber liner with a single slot is used to receive substrates, then substrate access is enabled, but RF current flow becomes azimuthally asymmetric causing non-uniform plasma processing
Solution Approach 1:
The single slot in the chamber liner is segmented into multiple slots (at least two slots) arranged symmetrically around the chamber axis. Each slot provides substrate access while the symmetric arrangement distributes RF current flow uniformly, preventing azimuthal asymmetry and ensuring uniform plasma processing across the substrate surface.
2Power
If RF current is launched from electrodes to excite plasma, then plasma generation is achieved, but RF current concentrates at slot edges causing electrical skews
Solution Approach 1:
The invention introduces deliberate geometric asymmetry through multiple symmetrically arranged slots to counteract the inherent asymmetry in RF current concentration at single slot edges. By arranging slots symmetrically (e.g., 180 degrees apart for two slots, or evenly distributed for three or more slots), the RF current paths are balanced, eliminating electrical skews and achieving uniform plasma distribution.
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 symmetric RF current flow through the liner assembly achieves uniform azimuthal symmetry of the plasma, resulting in improved processing results by eliminating azimuthal plasma skews and ensuring consistent etch or deposition rates across the substrate.
Implementation Method 1
RF current flow (shown by dotted lines I90) is perturbed by the slot 902, that is, the slot 902 creates area of high concentration I92 which can lead to an azimuthal asymmetry in the electromagnetic fields
Implementation Method 2
the process gas is excited into the plasma by the RF current launched from electrodes. The plasma decomposes the gas mixture into reactive species that perform the desired deposition or etch process.
Data Source
AI summary
The invention discloses a plasma processing apparatus comprising a chamber lid, a chamber body and a support assembly. The chamber body, defining a processing volume for containing a plasma, for supporting the chamber lid. The chamber body is comprised of a chamber sidewall, a bottom wall and a liner assembly. The chamber sidewall and the bottom wall define a processing volume for containing a plasma. The liner assembly, disposed inside the processing volume, comprises of three or more slots formed thereon for providing an axial symmetric RF current path. The support assembly supports a substrate for processing within the chamber body. With the liner assembly with several symmetric slots, the present invention can prevent electromagnetic fields thereof from being azimuthal asymmetry.