Annular Plasma Confinement Ring for Flow Conductance
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Solution Overview
Problem
Plasma processing in semiconductor manufacturing faces challenges with unconfined plasmas causing etch-byproduct deposition on chamber walls, leading to contamination and increased process costs, and existing confinement devices like slotted plasma confinement rings result in high flow resistance, especially at low pressures required for front-end of line applications.
Innovation Solution
An annular plasma confinement ring with a gap between the ring and chamber walls, combined with impedance confinement by adjusting the voltage ratio to reduce voltage supplied to the top electrode, enhances plasma confinement while minimizing flow resistance and power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a slotted plasma confinement ring is used to confine plasma, then plasma confinement is improved, but flow resistance increases and chamber pressure cannot be maintained at low levels
Solution Approach 1:
The confinement ring is divided into multiple discrete slots rather than being a continuous structure. This segmentation allows plasma to be confined in the radial direction while providing multiple separate pathways for gas flow, reducing overall flow resistance compared to a solid ring structure.
Solution Approach 2:
The confinement ring structure provides different properties in different regions: the radial walls provide plasma confinement while the slot openings provide flow conductance. This local differentiation of function allows simultaneous achievement of plasma confinement and acceptable flow characteristics.
2Productivity
If plasma is unconfined to maintain low chamber pressure, then flow conductance is improved, but etch-byproduct deposition on chamber walls causes contamination
Solution Approach 1:
The harmful plasma interactions with chamber walls are extracted and confined to a specific region by the confinement ring. The plasma is prevented from reaching the chamber walls where it would cause contamination, while the extracted essence of plasma confinement is maintained in the processing region.
Solution Approach 2:
The potential harm of unconfined plasma causing wall deposition is converted into a benefit by using the confinement ring to direct plasma energy precisely where needed for processing while preventing wall contamination. The confinement structure itself becomes the solution to the contamination problem it was designed to address.
3Reliability
If confinement ring structure is made more robust to improve plasma confinement, then plasma confinement is improved, but flow resistance increases
Solution Approach 1:
The confinement ring design balances structural robustness for plasma confinement with optimized slot geometry for flow conductance. The dynamic interplay between the confinement walls and slot openings allows the structure to maintain plasma confinement while minimizing flow resistance through proper dimensional ratios.
Solution Approach 2:
The slot dimensions, wall thickness, and opening-to-solid ratios are carefully optimized parameters that allow the confinement ring to provide adequate plasma confinement while maintaining acceptable flow conductance. By adjusting these parameters, the design achieves a balance between confinement effectiveness and flow resistance.
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 solution effectively confines plasma within the processing region, reduces chamber contamination, and maintains low chamber pressure, improving process repeatability and throughput by balancing plasma confinement and flow conductance.
Implementation Method 1
A plasma reactor includes an annular ring surrounding the top portion of the substrate support... effectively confines plasma within the processing region
Implementation Method 2
impedances of the top electrode, the dielectric seal, the substrate along with the substrate support, and plasma reduce a voltage supplied to the top electrode by a voltage ratio
Implementation Method 3
applying radio frequency (RF) power to a working gas supplied to a low pressure processing region... The resulting electric field creates a reaction zone in the processing region that excites the working gas into a plasma
Implementation Method 4
a dielectric seal placed between a top electrode and a process chamber body
Data Source
AI summary
The embodiments of the present invention generally relate to a plasma reactor. In one embodiment, a plasma reactor includes a substrate support is disposed in a vacuum chamber body and coupled to bias power generator. An RF electrode is disposed above the substrate support and coupled to a very high frequency power generator. A conductive annular ring is disposed on the substrate support and has a lower outer wall, an upper outer wall and an inner wall. A step is extends upward and outward from a lower outer wall and inward and downward from the upper outer wall. The inner wall disposed opposite the upper and lower outer wall. In other embodiments, the annular ring may be fabricated from a conductive material, such as silicon carbide and aluminum.