Conical Showerhead Top Plate Reducing Gas Recirculation
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Solution Overview
Problem
Substrate processing systems face issues with recirculation of secondary purge gas, which can trap particles and cause defects due to the symmetric configuration of showerheads, making it difficult to modulate the velocity or flow of the gas to prevent recirculation.
Innovation Solution
The implementation of a collar with conical surfaces and gas slits that direct secondary purge gas in a radially outward and downward direction, creating a laminar flow path to minimize recirculation regions, and the use of conical showerheads and top plates to redirect gas flow effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a symmetric showerhead configuration is used, then gas distribution uniformity is improved, but recirculation of secondary purge gas occurs causing particle trapping
Solution Approach 1:
The patent introduces asymmetric conical surfaces on the showerhead and top plate that break the symmetric flow pattern. The conical surfaces are positioned to create a preferential downward flow direction, preventing the recirculation that occurs with fully symmetric configurations while maintaining adequate gas distribution uniformity.
Solution Approach 2:
The conical surfaces are strategically positioned at specific locations on the showerhead and top plate to locally modify the flow characteristics. This localized modification creates downward flow bias in critical regions where recirculation occurs, without compromising the overall gas distribution uniformity across the substrate.
2Object-generated harmful factors
If secondary purge gas flow rate is increased to clear particles, then particle trapping is reduced, but gas flow modulation becomes difficult and recirculation persists
Solution Approach 1:
The conical surfaces provide a curved geometric feature that guides the gas flow in a controlled manner. The curvature of the conical surfaces creates a natural flow direction that promotes downward movement and prevents recirculation, allowing effective particle clearance at moderate flow rates without requiring extreme flow rate increases.
3Object-generated harmful factors
If conical surfaces are added to redirect gas flow, then recirculation is reduced, but device complexity increases
Solution Approach 1:
The conical surfaces utilize simple curved geometries that can be integrated into existing showerhead and top plate designs. These conical features provide effective flow redirection with relatively simple manufacturing requirements, avoiding the need for complex internal flow control mechanisms or multiple discrete components.
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 reduces recirculation and defects by ensuring a laminar gas flow between the showerhead and the processing chamber, enhancing the processing efficiency and reducing particle trapping.
Implementation Method 1
direct the secondary purge gas from the gas channel in a radially outward and downward direction... creating a laminar flow path to minimize recirculation regions
Data Source
AI summary
A processing chamber in a substrate processing system includes an upper surface, sidewalls, and a bottom surface and a showerhead connected to and extending downward from the upper surface of the processing chamber. The showerhead includes a stem portion and a base portion. An inverted conical surface is arranged adjacent to the upper surface and the sidewalls of the processing chamber and includes an angled surface arranged to redirect gas flow above the showerhead from a horizontal direction to a downward direction and into a gap between a radially outer portion of the base portion and the sidewalls of the processing chamber.