Dielectric Protrusion Waveguide for Plasma Uniformity
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Solution Overview
Problem
The controllability of plasma-generation position in semi-batch type film forming apparatuses using microwaves as the plasma excitation source is challenging due to localized plasma-generation and increased pressure within the processing container, making it difficult to uniformly process substrates rotating around a central axis.
Innovation Solution
The apparatus incorporates a plasma generation section with waveguides and protrusions made of dielectric material extending into the processing chamber, concentrating microwave energy and allowing for adjustable plasma density distribution by positioning reflection plates to optimize microwave power distribution and plasma generation across the substrate's surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If microwaves are used as plasma excitation source in semi-batch type film forming apparatus, then high-density plasma with low electron temperature can be generated, but plasma-generation position becomes localized and difficult to control
Solution Approach 1:
The waveguide is divided into multiple segments with dielectric protrusions at different radial positions. Each protrusion acts as an independent plasma generation zone, allowing the plasma generation region to be segmented and controlled across different radial positions rather than being localized to a single point.
Solution Approach 2:
Different regions of the waveguide are equipped with dielectric protrusions of varying sizes and positions to create locally optimized plasma generation characteristics. The protrusion dimensions and positions are specifically designed to control plasma density distribution at different radial locations, achieving uniform plasma processing across the substrate surface.
2Quantity of substance
If pressure inside processing container is increased, then more plasma can be generated, but plasma-generation position becomes harder to control
Solution Approach 1:
The waveguide structure with distributed dielectric protrusions segments the plasma generation process into multiple controlled zones. This segmentation allows plasma to be generated throughout the processing chamber volume rather than concentrating in a single location, enabling better control over plasma distribution even at increased pressures.
Solution Approach 2:
Dielectric protrusions act as intermediary structures that mediate between the microwave energy input and plasma generation. These protrusions concentrate and control microwave energy conversion to plasma at specific locations, serving as intermediaries that enable controllable plasma generation throughout the chamber rather than localized plasma formation.
3Ease of operation
If substrates rotate around central axis, then uniform processing can be achieved, but localized plasma generation creates non-uniform plasma distribution
Solution Approach 1:
Dielectric protrusions are positioned asymmetrically at different radial distances from the central axis, creating intentional asymmetry in the plasma generation structure. This asymmetric arrangement compensates for the rotational motion of substrates by providing enhanced plasma generation at outer radial positions where substrates move faster, achieving more uniform plasma exposure across the entire substrate surface.
Solution Approach 2:
The waveguide structure provides different plasma generation characteristics at different radial positions through locally optimized dielectric protrusions. Outer regions have protrusions configured to generate higher plasma density to compensate for the faster linear velocity of rotating substrates at those positions, creating locally adapted plasma conditions that result in overall uniform processing.
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 enhances the controllability of plasma-generation positions and ensures uniform plasma processing across the substrate, even at high pressures, by concentrating microwaves on protrusions and adjusting their power distribution radially, thereby improving the film forming process.
Implementation Method 1
The plasma generation section includes: at least one waveguide configured to define a wave guiding path above the placement stage and above the second region
Implementation Method 2
a microwave generator connected to the at least one waveguide
Implementation Method 3
a plurality of protrusions made of a dielectric material and configured to pass through a plurality of openings formed in a lower conductive part of the at least one waveguide to extend into the second region
Implementation Method 4
The plasma generation section is configured to generate plasma of a reactive gas in the second region
Data Source
AI summary
Provided is a film forming apparatus including a placement stage; a processing container that defines a processing chamber which accommodates the placement stage and includes a first region and a second region; a gas supply section that supplies a precursor gas to the first region; and a plasma generation section that generates plasma of a reactive gas in the second region. The plasma generation section includes: at least one waveguide that defines a wave guiding path above the placement stage and above the second region, a microwave generator connected to the at least one waveguide, and a plurality of protrusions made of a dielectric material. The protrusions pass through a plurality of openings formed in a lower conductive part of the at least one waveguide to extend into the second region. The protrusions are arranged in a radial direction with respect an axis of the placement stage.