Asymmetric RF Drive for Plasma Chamber Electrode
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Solution Overview
Problem
Conventional plasma chamber designs fail to compensate for non-uniformities in plasma density caused by asymmetries in chamber geometry, leading to asymmetrical plasma processes during semiconductor, display, and solar cell fabrication.
Innovation Solution
Asymmetrically coupling RF power to the electrode of a plasma chamber by offsetting the RF drive points towards the workpiece passageway, with a weighted mean position between the center and the passageway, to balance plasma density and process uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If RF power is coupled symmetrically to the electrode, then the plasma chamber geometry is simple and easy to manufacture, but plasma density asymmetry occurs due to the workpiece passageway causing non-uniform plasma processes
Solution Approach 1:
The patent applies asymmetry by intentionally creating an asymmetric RF power coupling configuration where the weighted mean position of RF drive points is offset toward the workpiece passageway. This asymmetric power distribution compensates for the geometric asymmetry introduced by the passageway, balancing the plasma density across the electrode surface and improving plasma process uniformity.
Solution Approach 2:
The patent implements local quality by distributing RF drive points at different positions along the electrode with different weighting factors. The weighted mean position is specifically located between the center and the workpiece passageway, creating localized variations in power coupling that compensate for regional plasma density differences caused by the passageway geometry.
2Manufacturing precision
If RF drive points are positioned offset toward the workpiece passageway, then plasma density asymmetry is reduced, but the RF power distribution becomes more complex
Solution Approach 1:
The patent changes the spatial parameters of RF drive point positions and their corresponding power weighting factors. By positioning the weighted mean of drive points at a specific location between the electrode center and the workpiece passageway, the system optimizes plasma density uniformity through parameter adjustment rather than structural modification.
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 approach effectively reduces plasma density asymmetry near the workpiece passageway, achieving improved spatial uniformity in plasma processes and minimizing non-uniformities in deposition or etching processes.
Implementation Method 1
coupling an RF power source to an electrode of a plasma chamber
Implementation Method 2
the plasma density is greater adjacent the end of the electrode closest to the passageway than it is adjacent the opposite end of the electrode
Data Source
AI summary
RF power is coupled to one or more RF drive points (50-56) on an electrode (20-28) of a plasma chamber such that the level of RF power coupled to the RF drive points (51-52, 55-56) on the half (61) of the electrode that is closer to the workpiece passageway (12) exceeds the level of RF power coupled to the RF drive points (53-54), if any, on the other half (62) of the electrode. Alternatively, RF power is coupled to one or more RF drive points on an electrode of a plasma chamber such that the weighted mean of the drive point positions is between the center (60) of the electrode and the workpiece passageway. The weighted mean is based on weighting each drive point position by the time-averaged level of RF power coupled to that drive point position. The invention offsets an increase in plasma density that otherwise would exist adjacent the end of the electrode closest to the passageway.