Focus Ring Asymmetry for Plasma Uniformity
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Solution Overview
Problem
Plasma processing in semiconductor manufacturing faces challenges with non-uniform process characteristics due to the temporal change and consumption of focus rings, leading to non-uniformity and reduced useful life.
Innovation Solution
A focus ring with an uneven pattern and protruding unit structures increases the surface area for plasma interaction, reducing the rate of temporal change and enhancing plasma uniformity by adjusting the electric field formation area around the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional focus ring with a flat surface is used, then the device structure is simple, but the plasma processing uniformity deteriorates due to non-uniform consumption and temporal change
Solution Approach 1:
The focus ring employs an asymmetric cross-sectional structure where the inner wall surface and outer wall surface have different profiles. The inner wall surface includes a first inclined surface and a first horizontal surface, while the outer wall surface includes a second inclined surface and a second horizontal surface at different heights. This asymmetric design creates non-uniform plasma interaction zones that compensate for the natural non-uniform consumption patterns, thereby improving plasma processing uniformity across the wafer surface.
Solution Approach 2:
Different regions of the focus ring are designed with distinct surface characteristics to address local plasma uniformity issues. The inner wall surface and outer wall surface have different inclinations and horizontal surface heights, creating localized variations in plasma interaction. This local quality differentiation allows each region to optimize plasma distribution specifically for its zone, improving overall processing uniformity.
2Duration of action of stationary object
If a focus ring with uniform consumption resistance is designed, then the useful life is extended, but the plasma interaction surface area is reduced
Solution Approach 1:
The asymmetric design with different inner and outer wall profiles creates varied plasma interaction zones that experience different consumption rates. This asymmetry distributes the plasma interaction load more evenly across the structure, preventing localized rapid consumption and thereby extending the overall useful life while maintaining adequate surface area for plasma interaction.
Solution Approach 2:
The focus ring utilizes vertical dimension variations through inclined surfaces and multi-level horizontal surfaces to create three-dimensional plasma interaction zones. This dimensional complexity increases the effective plasma interaction surface area without proportionally increasing material consumption, as the vertical profiles allow plasma to interact with multiple surface levels simultaneously.
3Area of stationary object
If the focus ring height is increased to maintain conductance, then the plasma interaction surface area increases, but the rate of height decrease accelerates
Solution Approach 1:
The asymmetric cross-sectional design with different inner and outer wall profiles distributes plasma interaction across varied surface areas at different heights. This asymmetry creates a more uniform consumption pattern across the entire structure, preventing localized rapid wear that would accelerate overall height decrease, thereby maintaining conductance without proportionally increasing the rate of height loss.
Solution Approach 2:
The focus ring design modifies the geometric parameters of the plasma interaction surfaces through specific inclinations and horizontal surface heights. By optimizing these parameters, the design increases the effective plasma interaction surface area while distributing the consumption load to maintain a controlled rate of height decrease, balancing conductance maintenance with structural longevity.
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 improves the uniformity of plasma processing characteristics and extends the useful life of the focus ring by reducing the rate of height decrease and maintaining conductance, ensuring consistent process outcomes.
Implementation Method 1
A focus ring with an uneven pattern and protruding unit structures increases the surface area for plasma interaction, reducing the rate of temporal change and enhancing plasma uniformity by adjusting the electric field formation area around the wafer.
Implementation Method 2
A focus ring with an uneven pattern and protruding unit structures increases the surface area for plasma interaction, reducing the rate of temporal change and enhancing plasma uniformity by adjusting the electric field formation area around the wafer.
Data Source
AI summary
A focus ring includes a main body and a plurality of unit structures. The main body has a ring shape. The unit structures are arranged in an uneven pattern and protrude from an upper surface of the main body.