Interleaved Vertical Plasma Source for Uniform Large-Area Exposure
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Solution Overview
Problem
Existing plasma sources face challenges in achieving uniform plasma exposure on large area substrates due to RF dielectric window size limitations, plasma non-uniformities, and capacitive coupling issues, particularly in systems with rotating susceptors, leading to non-uniform treatment and contamination.
Innovation Solution
A circular vertical plasma source with interleaved power and ground electrodes, decoupled plasma grounding, and a pedestal that is not coupled to ground, along with a rotating modulated gas cross-flow system, to ensure uniform plasma exposure and minimize contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional plasma source with RF dielectric window is used, then plasma generation is achieved, but plasma uniformity deteriorates due to window size limitations and capacitive coupling issues
Solution Approach 1:
The electrode structure is segmented into multiple discrete elements: upper electrodes (powered and ground) arranged in an interleaved pattern, and lower electrodes on the pedestal. This segmentation allows independent optimization of each electrode's function and position, enabling uniform plasma generation across large substrates by distributing the plasma generation zones evenly throughout the processing volume.
Solution Approach 2:
The patent transitions from a traditional single-plane electrode configuration to a three-dimensional electrode arrangement. Upper electrodes are positioned above the substrate plane while lower electrodes are positioned below, creating vertical plasma generation zones. This dimensional change allows plasma to be generated uniformly across the substrate area without being constrained by RF dielectric window size limitations.
2Reliability
If the pedestal is coupled to ground, then electrical stability is improved, but plasma uniformity deteriorates due to capacitive coupling
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the lower electrodes on the pedestal and the substrate. This dielectric barrier prevents direct capacitive coupling between the grounded pedestal and the substrate, thereby maintaining plasma uniformity while still allowing the pedestal to provide electrical stability through its ground connection. The dielectric layer acts as a mediator that decouples the electrical and plasma interaction pathways.
3Ease of operation
If a modular plasma source is used, then ease of insertion is improved, but plasma uniformity deteriorates due to non-uniform flux distribution
Solution Approach 1:
Different regions of the plasma source are assigned different functions to optimize local plasma characteristics. The upper powered electrodes generate plasma flux from above, while the upper ground electrodes and lower electrodes create additional plasma generation zones. This local quality differentiation ensures that each region contributes appropriately to achieving uniform overall plasma exposure, even in a modular configuration that can be easily inserted into the system.
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 achieves uniform plasma exposure across large substrates, reduces contamination, and enhances process uniformity by addressing capacitive coupling and plasma non-uniformities, thereby improving film quality and process efficiency.
Implementation Method 1
capacitive coupling issues
Implementation Method 2
a plasma source consisting of a volume where plasma is generated, and a way to expose a workpiece to a flux of charged particles and active chemical radical species
Data Source
AI summary
Embodiments disclosed herein include a plasma source including a ground electrode including a plurality of ground electrode portions. The plasma source also includes a power electrode including a plurality of power electrode portions. Ones of the power electrode portions are interleaved with ones of the ground electrode portions.