Focus Ring Lateral Gap Design for Plasma Etch Deposition Control
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Solution Overview
Problem
In plasma processing systems, material accumulation on the focus ring and workpiece support disrupts the etch process and causes damage, as it narrows the gap between the focus ring and the workpiece, leading to cooling circulation issues and material flaking.
Innovation Solution
Increasing the lateral distance between the upper tier of the focus ring and the workpiece to at least 3 mm, and optionally incorporating a ramped side wall between the tiers, helps prevent material accumulation and allows for easier monitoring and cleaning during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the focus ring is positioned close to the workpiece to maintain plasma confinement, then plasma processing efficiency is improved, but material deposition on the focus ring increases
Solution Approach 1:
The focus ring is designed with a two-tier structure where the upper tier is positioned at a greater lateral distance (at least 3 mm) from the workpiece compared to conventional single-tier rings. This dimensional adjustment in the lateral direction reduces material deposition while the lower tier maintains plasma confinement, effectively resolving the contradiction between processing efficiency and material accumulation.
2Manufacturing precision
If the gap between the focus ring and workpiece is reduced to improve plasma confinement, then etch process quality is improved, but material accumulation narrows the gap further causing cooling circulation issues
Solution Approach 1:
The focus ring is segmented into two distinct tiers: an upper tier positioned at a larger lateral distance (≥3 mm) from the workpiece to prevent material accumulation and maintain cooling circulation, and a lower tier positioned closer to the workpiece to maintain plasma confinement and etch quality. This segmentation allows both contradictory requirements to be satisfied simultaneously by different parts of the same structure.
3Device complexity
If a conventional single-tier focus ring is used, then device complexity is reduced, but material deposition causes flaking and damage
Solution Approach 1:
The invention transitions from a conventional single-tier focus ring to a two-tier structure with the upper tier positioned at a greater lateral distance (at least 3 mm) from the workpiece. This dimensional change effectively prevents material deposition on the upper tier, eliminating the flaking and damage problems associated with single-tier rings, while maintaining acceptable device complexity.
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 solution effectively reduces material deposition on the focus ring and workpiece support, maintaining process integrity and preventing damage, while allowing for improved cooling circulation and easier maintenance.
Implementation Method 1
a plasma source configured to generate a plasma
Data Source
AI summary
Focus ring assemblies for plasma processing apparatus are provided. In one example implementation, an apparatus includes a plasma source configured to generate a plasma. The apparatus includes a chamber configured to receive a workpiece. The apparatus includes a workpiece support contained in the chamber and configured to support the workpiece. The apparatus includes a focus ring assembly. The focus ring assembly includes a focus ring having an upper tier and a lower tier. An inner edge of the upper tier can be separated a lateral distance of at least about 3 mm from an outer edge of the workpiece located on the workpiece support.