Auxiliary Chamber Evacuation for Load Lock Pressure Management
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Solution Overview
Problem
Current vacuum processing systems for semiconductor manufacturing face significant pumping time challenges, particularly in load lock enclosures, due to the rapid increase in pressure at booster pumps during the evacuation process, which slows down the rotational speed and increases the overall evacuation time.
Innovation Solution
The system employs a configuration where an auxiliary chamber is located downstream of the first pumping means, allowing gas to be drawn from the enclosure into the auxiliary chamber through the first pumping means, creating a pressure difference that enhances the rotation speed of the pumping mechanism and reduces evacuation time. Additionally, using multiple smaller auxiliary chambers instead of a single large one further reduces the final equilibrium pressure and evacuation duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a pre-evacuated auxiliary chamber is used to initiate the pump down process, then the initial evacuation speed is improved, but the pressure equalization causes a slug of high pressure fluid to rush into the booster pumps, significantly slowing down the rotational speed of the pumping mechanism
Solution Approach 1:
The invention introduces an intermediary chamber positioned between the load lock enclosure and the booster pumps. This intermediary chamber acts as a buffer that receives the high pressure fluid slug during pressure equalization, preventing it from directly impacting the booster pumps. The intermediary chamber is then evacuated by backing pumps, allowing the booster pumps to maintain their rotational speed without significant slowdown, thus eliminating the time delay while still achieving rapid initial evacuation.
2Duration of action of moving object
If the auxiliary chamber is connected directly to the booster pumps, then the pump down cycle time is reduced, but the rotational speed of the booster pumps varies significantly from maximum value, reducing evacuation efficiency
Solution Approach 1:
The invention segments the evacuation system into distinct functional zones: the load lock enclosure, the intermediary chamber, and the booster pump section. By dividing the system in this way, the pressure equalization process occurs in the intermediary chamber rather than directly at the booster pumps, allowing the pumps to operate at consistent high speed while the overall pump down cycle remains efficient.
3Quantity of substance
If a single large auxiliary chamber is used, then the initial pressure equalization is effective, but the final equilibrium pressure achieved is not sufficiently low, requiring additional evacuation time
Solution Approach 1:
The intermediary chamber serves as a mediator that enables a two-stage pressure reduction process. First, the load lock enclosure rapidly equalizes with the intermediary chamber, achieving effective pressure reduction. Second, the intermediary chamber is evacuated by backing pumps to achieve the final low equilibrium pressure. This intermediary approach allows both effective initial pressure equalization and achievement of sufficiently low final pressure levels.
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 the evacuation time of the enclosure by maintaining faster rotational speeds of the pumping mechanisms and achieving lower final pressures, thereby improving the throughput and efficiency of the vacuum processing system.
Implementation Method 1
causes a large 'slug' of high pressure fluid to rush from the load lock enclosure 1 towards the evacuated auxiliary chamber 4
Data Source
AI summary
A system for evacuating an enclosure is provided. The system includes a first vacuum pump having an inlet selectively connectable to an outlet from the enclosure. A second vacuum pump is also provided together with a conduit for connecting an exhaust of the first vacuum pump to an inlet of the second vacuum pump. An auxiliary chamber is provided, this chamber being selectively connectable to the conduit such that, in a first state, gas can be drawn from the auxiliary chamber by the second vacuum pump in isolation from the enclosure, and, in a second state, gas can be drawn from the enclosure to the auxiliary chamber through the first vacuum pump.