Inductively Coupled Plasma Source with Segmented Coils
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Solution Overview
Problem
As substrate size increases and device geometry shrinks, achieving uniform etch or deposition rates across the entire surface of substrates in plasma processing becomes challenging due to chamber design asymmetries, temperature distribution non-uniformities, and gas distribution control issues in inductively coupled plasma sources.
Innovation Solution
A plasma reactor with axially symmetrical design featuring three concentric coil antennas (inner, middle, and outer) and a symmetrical exhaust chamber, along with independent RF power control and dielectric windows for precise plasma density management, ensures uniform plasma distribution and process uniformity across larger substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If two concentrically arranged coil antennas are used over the chamber ceiling, then uniformity of etch rate distribution can be optimized by adjusting RF power levels, but this approach becomes inadequate as workpiece diameter and chamber diameter increase
Solution Approach 1:
The single coil antenna system is segmented into three separate coil antennas (inner, middle, and outer coils) positioned at different radial locations. Each coil can be independently controlled with separate RF power sources, allowing precise local adjustment of plasma density across different zones of the large substrate, thereby maintaining etch rate uniformity despite the increased chamber diameter.
Solution Approach 2:
Different regions of the chamber are assigned different coil antennas with independent RF power control. The inner coil serves the central region, the middle coil serves the intermediate region, and the outer coil serves the peripheral region. This local quality approach allows each zone to be optimized independently for uniform plasma distribution across the entire large substrate surface.
2Area of stationary object
If larger substrates are processed, then device size increases, but achieving uniform plasma distribution becomes more difficult due to chamber design asymmetries and temperature distribution non-uniformities
Solution Approach 1:
The chamber is divided into three radial zones served by separate coil antennas, each with independent RF power control. This segmentation allows asymmetric compensation - each coil can be tuned to compensate for local asymmetries and temperature non-uniformities in its specific zone, maintaining overall process uniformity across the large substrate.
Solution Approach 2:
The system employs independent RF power level adjustments for each of the three coil antennas, allowing dynamic parameter changes to compensate for temperature distribution non-uniformities and chamber design asymmetries. By varying the RF power delivered to each coil, the plasma density can be optimized locally across different regions of the large substrate.
3Manufacturing precision
If three concentric coil antennas are used with independent RF power control, then plasma density uniformity is improved, but device complexity increases
Solution Approach 1:
While segmentation into three coils increases complexity, it enables precise plasma density control across large substrates. The segmented approach allows independent optimization of each radial zone, achieving uniformity that cannot be obtained with fewer coils, especially for substrates larger than 12 inches.
Solution Approach 2:
The three-coil configuration with independent RF power sources provides multi-functionality: it can process various substrate sizes (8-inch, 12-inch, and larger), compensate for different asymmetry patterns, and adapt to different process requirements by adjusting individual coil powers. This universal capability justifies the increased 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
The solution provides enhanced control over plasma density and uniformity, improving the consistency of etch or deposition rates across larger substrates by addressing asymmetries and non-uniformities, thus facilitating more efficient plasma processing.
Implementation Method 1
plasma is generated by inductive coupling of RF power to process gases inside the chamber
Data Source
AI summary
A plasma reactor for processing a workpiece includes a reactor chamber having a ceiling and a sidewall and a workpiece support facing the ceiling and defining a processing region, and a pair of concentric independently excited RF coil antennas overlying the ceiling and a side RF coil concentric with the side wall and facing the side wall below the ceiling, and being excited independently.