Ground Electrode Asymmetry for Plasma Uniformity
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Solution Overview
Problem
The challenge in plasma processing is the non-uniform plasma density across the surface of a wafer substrate, particularly with lower density near the edge, which hinders efficient miniaturization and performance of electronic components.
Innovation Solution
A ground electrode with a peripheral portion thicker than the central portion and a heater layer with varying permittivity between inner and outer portions is used to adjust the gap between electrodes, enhancing plasma density uniformity by intensifying the electric field and plasma intensity near the edge of the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If plasma is formed by adding large amounts of energy to a gas above a masked surface of a wafer substrate, then plasma processing can be performed to enable miniaturization and higher functions of electronic components, but non-uniform plasma density occurs across the substrate surface with lower density at the edge
Solution Approach 1:
The ground electrode is designed with non-uniform thickness where the peripheral portion is thicker than the central portion. This creates different local properties: the thicker peripheral portion reduces the gap between electrodes at the edges, intensifying the electric field and plasma density in regions that previously had lower density, thereby achieving more uniform plasma distribution across the substrate surface
2Manufacturing precision
If the gap between electrodes is reduced to intensify the electric field and plasma density near the edge of the substrate, then plasma density uniformity is improved, but the device structure becomes more complex
Solution Approach 1:
The ground electrode employs an asymmetric thickness distribution where the peripheral portion is deliberately made thicker than the central portion. This asymmetric design allows the gap between electrodes to be non-uniform: smaller at the periphery to intensify the electric field and plasma density at the edges, while maintaining a larger gap at the center. This single structural modification achieves plasma uniformity without requiring multiple separate components or complex adjustment mechanisms
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 configuration achieves a more uniform plasma density across the substrate, improving the miniaturization and performance of electronic components by ensuring consistent plasma distribution from the edge to the center.
Implementation Method 1
The heater layer includes an inner portion and an outer portion surrounding the inner portion. A permittivity of the outer portion is greater than a permittivity of the inner portion
Implementation Method 2
intensifying the electric field and plasma intensity near the edge of the substrate
Implementation Method 3
plasma is formed above a masked surface of a wafer substrate by adding large amounts of energy to a gas
Data Source
AI summary
A device includes a pedestal. The pedestal includes a ground electrode, a central portion, and a peripheral portion. The ground electrode includes a top surface from which the peripheral portion is projected, thereby having a height difference between the central portion and the peripheral portion.