Baffled Liner Cover for Semiconductor Thermal Processing
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Solution Overview
Problem
In thermal processing of semiconductor substrates, the open-ended design of thermal ovens allows particles from the quartz bell jar dome to fall onto the wafers, causing contamination and reducing yield, while sealing the top would obstruct the flow of processing gases.
Innovation Solution
A cover with restricted apertures, preferably less than 10% of the surface area, is placed over the liner to block particles while allowing gas flow, featuring horizontal apertures and convolute passageways to prevent particle entry while maintaining gas circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the top of the liner is left open to allow gas flow, then processing gas can flow upward and exit the liner, but particles from the quartz bell jar dome can fall onto the wafers causing contamination
Solution Approach 1:
The cover is segmented with multiple small apertures distributed across its surface, allowing gas flow while blocking particles. The apertures are arranged to provide sufficient gas permeability while maintaining particle filtration capability.
Solution Approach 2:
The cover has different properties in different regions: the overall structure provides particle blocking, while the distributed apertures provide localized gas flow paths. The aperture size and distribution are optimized to balance gas flow requirements with particle exclusion.
2Object-affected harmful factors
If the top of the liner is sealed to block particles, then particle contamination is prevented, but processing gas flow is obstructed
Solution Approach 1:
The cover functions as a porous barrier with apertures occupying no more than 10% of the cover surface area. This porous structure allows gas molecules to pass through while blocking larger particle contaminants from the bell jar dome.
Solution Approach 2:
The cover acts as an intermediary component between the open liner top and the particle source (bell jar dome). It mediates the conflict between gas flow requirements and particle exclusion by providing a selective barrier that allows gas while blocking particles.
3Productivity
If apertures larger than 10% of cover area are used, then gas flow is improved, but particle blocking effectiveness is reduced
Solution Approach 1:
The aperture area ratio is controlled at no more than 10% of the cover surface area. This parameter optimization ensures sufficient gas flow while maintaining effective particle blocking. The specific aperture size, shape, and distribution are tuned to achieve the desired balance.
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 cover effectively prevents particle contamination while ensuring uninterrupted gas flow, enhancing the reliability and yield of the thermal processing by trapping particles and entraining lighter ones away from the substrate area.
Implementation Method 1
A cover with restricted apertures, preferably less than 10% of the surface area, is placed over the liner to block particles while allowing gas flow
Implementation Method 2
The cover effectively prevents particle contamination while ensuring uninterrupted gas flow, enhancing the reliability and yield of the thermal processing by trapping particles and entraining lighter ones away from the substrate area
Data Source
AI summary
A baffled liner cover supported at the top of a liner surrounding a wafer support tower for semiconductor thermal processing. The cover may present a continuous horizontal surface for preventing particles from falling within the liner but present horizontal extending gas passageways in a baffle assembly to allow the flow of processing gas through the cover. In one embodiment, the baffle assembly includes a cup-shaped member disposed in a central aperture of a top plate having an open top, a continuous bottom, horizontal holes through the sides, and a flange around sides defining a convolute annular passage. Alternatively, the planar top plate may included slanted holes therethrough or vertical holes occupying a small fraction of the surface area. The liner and cover may be composed of quartz, silicon carbide, or preferably silicon.