Exhaust Conduit Flow Restrictor for Semiconductor Gas Migration
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Solution Overview
Problem
The existing pumping arrangements in semiconductor fabrication processes face contamination issues due to the backward migration of light gases like hydrogen from one process chamber to another, which is exacerbated by the use of a common primary pump and conduit system, leading to potential film defects and equipment reliability concerns.
Innovation Solution
The implementation of a conduit system with a flow restrictor and purge gas delivery to create a Venturi effect, increasing the local density of gases and inhibiting the backward migration of contaminants by achieving choked flow conditions, thereby suppressing the migration of unwanted components from one chamber to another.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common primary pump and conduit system is used to evacuate multiple process chambers, then the complexity and footprint of the pumping arrangement is reduced, but contamination occurs due to backward migration of light gases like hydrogen from one chamber to another
Solution Approach 1:
A flow restrictor is introduced as an intermediary component in the common exhaust conduit. This restrictor creates a pressure differential that acts as a barrier, preventing light gases like hydrogen from migrating backward between chambers while still allowing the common pump system to function. The flow restrictor mediates between the need for a simplified common pump arrangement and the requirement to prevent contamination.
Solution Approach 2:
The system changes the pressure parameter along the exhaust conduit by introducing a flow restrictor. This creates a localized pressure increase downstream of the restrictor, which reverses the pressure gradient that would otherwise drive backward migration of light gases. By modifying the pressure distribution, the system prevents contamination while maintaining a common pump architecture.
2Object-affected harmful factors
If separate primary pumps are used for each process chamber to prevent contamination, then contamination is avoided, but the complexity, footprint and power requirements of the pumping arrangement increase
Solution Approach 1:
The invention merges multiple primary pump functions into a single common primary pump system while using a flow restrictor to maintain isolation between chambers. This combining approach reduces the number of pumps from multiple separate primary pumps to one shared unit, thereby reducing complexity and footprint while the flow restrictor ensures contamination prevention comparable to separate pump systems.
Solution Approach 2:
The flow restrictor serves as an intermediary that enables the merging of pump systems. It allows the common primary pump to effectively function as multiple isolated pumping systems by creating pressure barriers that prevent cross-contamination, thus achieving the benefits of separate pumps without the drawbacks of multiple pump units.
3Object-affected harmful factors
If the cross sectional area of the conduit is reduced to increase gas density and inhibit contaminant migration, then contamination is reduced, but the pressure drop and power requirements increase
Solution Approach 1:
Instead of reducing the cross-sectional area of the entire exhaust conduit, the flow restrictor creates a localized reduction in area at a specific position. This localized restriction is sufficient to create the necessary pressure differential to prevent contaminant migration, while minimizing the overall impact on gas flow and power requirements compared to a uniformly restricted conduit.
Solution Approach 2:
The flow restrictor applies partial action by creating a localized pressure barrier only where needed to prevent contaminant migration. Rather than restricting the entire conduit system, the restriction is applied selectively at the critical location, achieving the necessary contaminant prevention with minimal impact on overall system performance and power consumption.
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 solution effectively reduces contamination by minimizing the backward transport of contaminants, allowing for a simpler and more reliable pumping arrangement with a single primary pump, while maintaining process compatibility and reducing equipment size and power requirements.
Implementation Method 1
The implementation of a conduit system with a flow restrictor and purge gas delivery to create a Venturi effect, increasing the local density of gases and inhibiting the backward migration of contaminants by achieving choked flow conditions
Data Source
AI summary
Apparatus for conveying waste streams exhausted from first and second chambers is provided. The apparatus comprises first conduit means comprising an inlet for receiving a waste stream exhausted from the first chamber, and an outlet, and a second conduit means comprising an inlet for receiving a waste stream exhausted from a second chamber, and an outlet. The outlets of the first and second conduit means are connected together. The first conduit means comprises means for generating sonic choking of gas being conveyed towards the outlet of the first conduit means in order to inhibit migration of a component of the waste stream exhausted from the second chamber towards the first chamber.