C-Shroud Geometry for Plasma Uniformity and Ring Strength
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Solution Overview
Problem
Conventional confinement rings in semiconductor processing chambers face challenges in maintaining plasma uniformity and mechanical strength while extending their usage life, often requiring significant hardware changes or compromising the integrity of the plasma confinement.
Innovation Solution
A confinement ring design featuring a sloped lower horizontal section and tapered slots, which modulates plasma uniformity without altering other hardware components, and optimizes wear distribution to extend the ring's usage life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the shape of the confinement ring is changed to increase the volume of the process region, then plasma uniformity is improved, but mechanical strength is compromised
Solution Approach 1:
The invention applies different geometric characteristics to different sections of the confinement ring. The lower horizontal section features a sloped top surface that increases volume and improves plasma uniformity, while the vertical section maintains a consistent thickness to preserve mechanical strength. This local differentiation allows each section to optimize for its specific function.
Solution Approach 2:
The invention introduces a slope in the vertical dimension of the lower horizontal section's top surface. This dimensional change increases the volume of the process region without requiring changes to the horizontal dimensions or overall structure, thereby improving plasma uniformity while maintaining mechanical integrity.
2Reliability
If the design of the confinement ring is modified to extend the process region, then plasma confinement is improved, but device complexity increases
Solution Approach 1:
The invention extracts and modifies only the lower horizontal section of the confinement ring by adding a sloped top surface. This localized modification extends the process region and improves plasma confinement without requiring changes to other hardware components such as the processing chamber spacer plate or mating hardware.
Solution Approach 2:
The modified lower horizontal section with its sloped top surface serves multiple functions: it extends the process region volume, improves plasma uniformity, and maintains plasma confinement. This single geometric modification achieves multiple performance improvements simultaneously.
3Strength
If the thickness of the lower horizontal section is increased to maintain mechanical strength, then strength is improved, but plasma uniformity deteriorates
Solution Approach 1:
The invention creates a thickness gradient in the lower horizontal section by sloping the top surface while keeping the bottom surface flat. This results in greater thickness near the inside radius (improving mechanical strength) and smaller thickness at the lower inner radius (improving plasma uniformity), allowing both requirements to be satisfied simultaneously.
Data Source
AI summary
A confinement ring for use in a plasma processing chamber includes an upper horizontal section, a vertical section, and a lower horizontal section. The upper horizontal section extends between an upper inner radius and an outer radius of the confinement ring, The lower horizontal section extends between an lower inner radius and the outer radius of the confinement ring, and includes an extension section that extends to the lower inner radius. A top surface of the lower horizontal section provides for an angle down toward the lower inner radius. The vertical section is disposed between the outer radius and an inside radius of the confinement ring. The vertical section connects the upper horizontal section to the lower horizontal section of the confinement ring.