Angled Focus Ring Geometry for Uniform Plasma Etching
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Solution Overview
Problem
Plasma-based semiconductor processing tools often result in non-uniform etch rates across wafers due to uneven plasma distribution, leading to structural variations and reduced processing yield.
Innovation Solution
A focus ring with an angled inner wall and specific dimensions is used to direct plasma uniformly across the wafer, reducing plasma overlap and ensuring etch rate uniformity by configuring the inner diameter and outward angle of the inner wall to minimize plasma overlap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma is generated in a plasma-based semiconductor processing tool, then etching of semiconductor materials can be performed, but non-uniform plasma distribution causes non-uniform etch rates across the wafer
Solution Approach 1:
A focus ring is introduced as an intermediary component between the plasma source and the wafer. The focus ring receives plasma from the plasma source and redirects it toward the wafer surface, acting as a mediator that shapes and directs plasma flow to achieve more uniform distribution across the wafer surface, thereby improving etch rate uniformity while maintaining productivity
Solution Approach 2:
The focus ring changes the physical parameters of plasma distribution by redirecting plasma at specific angles. The angled inner wall of the focus ring modifies the plasma flow direction and distribution pattern, transforming the non-uniform plasma distribution into a more uniform pattern across the wafer surface, thus resolving the contradiction between etching efficiency and uniformity
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 focus ring enhances etch rate uniformity across the wafer, reducing structural variations and increasing processing yield by minimizing plasma overlap, thereby improving the quality of semiconductor devices.
Implementation Method 1
A plasma-based semiconductor processing tool may be used to etch various types of semiconductor materials from a substrate
Implementation Method 2
The focus ring may include an angled inner wall that is angled away from a center of the focus ring to direct plasma toward the wafer
Implementation Method 3
A plasma-based semiconductor processing tool may be used to etch various types of semiconductor materials from a substrate
Data Source
AI summary
A focus ring for a plasma-based semiconductor processing tool is designed to provide and/or ensure etch rate uniformity across a wafer during a plasma etch process. The focus ring may include an angled inner wall that is angled away from a center of the focus ring to direct a plasma toward the wafer. The angle of the angled inner wall may be greater than approximately 130 degrees relative to the top surface of the wafer and/or may be less than approximately 50 degrees relative to an adjacent lower surface of the focus ring to reduce and/or eliminate areas of overlapping plasma on the wafer (which would otherwise cause non-uniform etch rates). Moreover, an inner diameter may be configured to be in a range of approximately 209 millimeters to 214 millimeters to further reduce and/or eliminate areas of overlapping plasma on the wafer. In this way, the focus ring provides and/or increases etch rate uniformity across the wafer, which may reduce structural variations across semiconductor devices being formed on the wafer and/or may increase processing yield.