Staggered Vacuum Lock System for Substrate Transfer
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Solution Overview
Problem
Vacuum processing systems face inefficiencies due to the slow transport and pumping times required when moving substrates from atmospheric to vacuum environments, leading to reduced throughput and potential defects from particle contamination and water vapor absorption.
Innovation Solution
The implementation of a staggered vacuum lock system that gradually introduces substrates into a vacuum environment using multi-substrate carriers, reducing the number of substrates transferred at once and minimizing exposure to atmospheric conditions, allowing for smaller vacuum lock chambers and slower actuation, which reduces particle contamination and water vapor absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cassettes are transported directly into vacuum environment, then substrate transfer efficiency is improved, but particle contamination and water vapor absorption increase
Solution Approach 1:
The vacuum lock system is divided into multiple chambers (first vacuum lock, second vacuum lock, third vacuum lock) with progressively improving vacuum levels. Substrates are transferred through these segmented chambers in stages, allowing gradual adaptation to vacuum conditions while minimizing contamination at each transition point.
Solution Approach 2:
Multiple vacuum lock chambers serve as intermediary zones between atmospheric and high vacuum environments. These intermediate chambers with progressive vacuum levels act as buffer zones that reduce the shock of direct atmospheric-to-vacuum transition, minimizing particle generation and water vapor outgassing.
2Productivity
If large gate valves and large pump systems are used to accommodate full cassettes, then complete substrate batch processing is enabled, but system size and pumping time increase
Solution Approach 1:
Instead of using one large vacuum chamber to accommodate entire cassettes, the system segments the vacuum environment into multiple smaller chambers (first, second, and third vacuum locks plus processing chambers). Each chamber is smaller and can be pumped more quickly, yet the segmented system collectively handles complete substrate batches through multi-carrier coordination.
Solution Approach 2:
Multiple single-substrate carriers are used in parallel to transport complete batches of substrates through the segmented vacuum system. By combining the throughput of multiple smaller carriers, the system achieves batch processing capability without requiring large individual vacuum chambers.
3Ease of operation
If cassettes are kept in atmospheric environment, then substrate loading is simplified, but water vapor absorption increases
Solution Approach 1:
Substrates are pre-loaded into carriers in the atmospheric environment of the front end module, which is maintained at a lower humidity level than external atmospheric conditions. This preliminary loading action occurs before substrates are exposed to the full atmospheric environment during vacuum lock transitions, reducing water vapor absorption while maintaining operational simplicity.
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 approach enhances processing throughput by reducing the time spent in atmospheric environments, minimizing particle introduction, and efficiently managing vacuum pumping, thereby increasing the mean time between failures and services.
Implementation Method 1
a linear motor moves a carrier
Implementation Method 2
a first vacuum lock chamber, a second vacuum lock chamber, and a third vacuum lock chamber, each maintain a different vacuum level
Data Source
AI summary
Introduction of substrates into vacuum environment is accomplish by gradually reducing the number of substrates being transferred simultaneously as the clean and evacuated environment is progressed. Cassettes are maintained in clean atmospheric environment and do not enter the vacuum environment. Several vacuum locks are linearly staggered so as to introduce progressively higher level of vacuum environment. The number of substrates transported through this arrangement is a portion of the number of substrates present in each cassette. The staggered vacuum locks lead to a series of processing chambers, wherein a yet smaller number of substrates, e.g., one or two, are transported.