Redundant Vacuum Pumping System for Semiconductor Pressure Stability
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Solution Overview
Problem
Existing redundant vacuum pumping systems in the semiconductor industry suffer from pressure hunting and contamination when a pump fails, leading to potential wafer damage and financial losses, as they are unable to maintain constant pressure conditions effectively.
Innovation Solution
A redundant vacuum pumping system comprising a primary roots pump and two parallel pumping sub-systems, each with a secondary roots pump and a positive displacement pump, configured to operate at the same flow rate, allowing the primary roots pump to maintain pressure if one sub-system fails, and an optional bypass duct for handling failures of the primary roots pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant pumping system with two parallel sub-systems is used, then system reliability is improved, but pressure stability deteriorates due to pressure hunting when a pump fails
Solution Approach 1:
The pumping system is divided into a primary roots pump and two separate pumping sub-systems arranged in parallel. Each sub-system can independently handle the full pumping load, allowing seamless failover while maintaining pressure stability through the primary pump's continuous operation at reduced capacity.
Solution Approach 2:
The primary roots pump operates in advance to maintain a reservoir of vacuum pressure in the process chamber. This preliminary action ensures that when a sub-system fails, the primary pump can immediately compensate without causing pressure hunting, as it has already been actively managing the vacuum environment.
2Reliability
If a redundant pumping system is used, then system reliability is improved, but contamination risk increases due to pressure fluctuations during failure
Solution Approach 1:
The primary roots pump acts as a cushioning element that maintains a stable pressure reservoir in the process chamber. This beforehand cushioning prevents pressure fluctuations that would otherwise cause contamination when a sub-system fails, as the primary pump absorbs the shock of the failure and maintains stable conditions.
3Productivity
If two parallel pumping sub-systems are used, then flow rate capability is improved, but system complexity increases
Solution Approach 1:
Each pumping sub-system is designed to be universally capable of handling the full pumping load independently. This multi-functionality allows either sub-system to take over completely if needed, simplifying the control logic compared to systems requiring load-sharing coordination, while maintaining high flow rate capability through parallel architecture.
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 ensures constant pressure in the process chamber even during pump failures, preventing pressure hunting and contamination, and allows for automatic valve actuation to maintain system stability and efficiency.
Implementation Method 1
a roots pump, also called vacuum booster, and a backing pump are typically combined. The roots pump allows for the handling of the high flow rate and the backing pump, thanks to its high compression ratio, allows for reaching a sufficiently low end-pressure.
Implementation Method 2
the backing pump, thanks to its high compression ratio, allows for reaching a sufficiently low end-pressure.
Implementation Method 3
For each pumping sub-system, a valve is positioned on the duct connecting the roots pumps and the process chamber.
Data Source
AI summary
The present invention relates to a redundant vacuum pumping system (300) and a pumping method using this system, comprising a primary roots pump (302), a first pumping sub-system (310) and a second pumping sub-system (320), wherein the first pumping sub-system (310) and the second pumping sub-system (320) are arranged to pump in parallel the gas evacuated by the primary roots pump (302), the first pumping sub-system (310) comprising a first secondary roots pump (311) and a first positive displacement pump (312) and a first valve (313) positioned between the gas discharge outlet (302b) of the primary roots pump (302) and the gas suction inlet (311a) of the first secondary roots pump (311), and the second pumping sub-system (320) comprising a second secondary roots pump (311) and a second positive displacement pump (312) and a second valve (323) positioned between the gas discharge outlet (302b) of the primary roots pump (302) and the gas suction inlet (321a) of the second secondary roots pump (321). According to the invention, the first pumping sub-system (310) and the second pumping sub-system (320) are configured to pump at a same flow rate, and the primary roots pump (302) is configured to be able to pump at a flow rate F equal to the pumping flow rate of the primary pumping sub-system (310) plus the pumping flow rate of the secondary pumping sub-system (320).