Graphite Liner Film Stabilization via Chemical Conversion
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Solution Overview
Problem
Graphite liners in ion implantation systems suffer from erosion and film delamination issues due to ion beam interaction, leading to frequent replacements and particle excursions, which conventional methods like surface densification and roughening fail to adequately address.
Innovation Solution
A carbon-based substrate with a microscopically textured surface overlying a macroscopically textured surface, formed through chemical conversion to create a non-stoichiometric silicon and carbon surface, enhancing film retention and erosion resistance while maintaining low weight and machining ability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphite liners are used to shield the vacuum system from ion beam damage, then the vacuum system is protected, but the graphite liner suffers from erosion and film delamination leading to frequent replacement
Solution Approach 1:
The patent applies parameter changes by modifying the surface properties of the graphite liner through chemical vapor deposition (CVD) to create a diamond-like carbon coating. This changes the surface hardness, erosion resistance, and thermal conductivity parameters of the graphite liner, allowing it to withstand ion beam exposure longer while maintaining its protective function.
Solution Approach 2:
The patent uses composite materials by combining graphite with a diamond-like carbon coating layer. The graphite substrate provides structural integrity and thermal management, while the diamond-like carbon surface layer provides erosion resistance and reduced sputtering. This composite structure resolves the contradiction between protection function and component lifetime.
2Strength
If the graphite liner surface is densified to improve lifetime, then surface strength is improved, but material liberation from the surface is not reduced
Solution Approach 1:
The patent changes the surface parameters by depositing a diamond-like carbon coating that has different physical and chemical properties than bulk graphite. The coating has higher bond strength and lower sputtering yield, simultaneously improving surface strength and reducing material liberation when exposed to ion beams.
3Stability of the object's composition
If the surface is roughened mechanically to mitigate problems, then surface adhesion is improved, but particles can be trapped in the roughened surface
Solution Approach 1:
The patent changes the surface parameters through CVD coating deposition, which can be controlled to create a surface with optimal roughness characteristics. The diamond-like carbon coating provides good adhesion through controlled surface morphology while the coating material itself is less prone to generating particles compared to mechanically roughened graphite surfaces.
4Reliability
If a chemical conversion process is applied to create a non-stoichiometric silicon and carbon surface, then film retention and erosion resistance are enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes through a chemical vapor deposition process that converts the graphite surface into a diamond-like carbon structure. This chemical transformation enhances film retention and erosion resistance by creating stronger carbon-carbon bonds and a more stable surface composition, despite the added manufacturing step.
Solution Approach 2:
The patent replaces mechanical surface treatment methods with a chemical vapor deposition process. Instead of mechanically roughening or densifying the surface, the CVD process chemically transforms the surface properties, providing better control over surface morphology and composition while reducing particle generation.
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 chemical conversion of graphite liners results in a longer lifetime, improved performance, and reduced particle contamination, offering superior film retention and erosion resistance with enhanced thermal and electrical conductivity.
Implementation Method 1
formed through chemical conversion to create a non-stoichiometric silicon and carbon surface
Implementation Method 2
graphite material can be eroded from the graphite liner by the ion beam, thus causing a need for frequent replacement. Such erosion of the graphite liner may arise through physical or chemically-enhanced sputtering
Implementation Method 3
Such erosion of the graphite liner may arise through physical or chemically-enhanced sputtering, or through thermal ion beam milling
Implementation Method 4
the graphite liner can be coated by back-sputtered material from the target substrate or from other terminating surfaces (e.g., a tuning Faraday) struck by the ion beam
Data Source
AI summary
An electrically conductive component is provided for a near-wafer environment of an ion implantation system, where the component has a carbon-based substrate having a microscopically textured surface overlying a macroscopically textured surface. The macroscopically textured surface is a mechanically, chemically, or otherwise roughened surface. The microscopically textured surface can be a converted surface formed by a chemical reaction forming a non-stoichiometric silicon and carbon surface. The one or more components can be a dose cup, exit aperture, and tunnel wall. The carbon-based substrate can be graphite. The microscopically textured surface can be a modified graphite surface. No defined interface layer exists between the microscopically textured surface and macroscopically textured surface. The carbon-based graphite is selected based on a final porosity and grain size of the graphite.