Invited Paper VT-TuM1
Applications for Mobile Vacuum Environments in Semiconductor Manufacturing

Tuesday, October 20, 2015, 8:00 am, Room 230B

The majority of processes found in semiconductor manufacturing occur within a vacuum environment. A vacuum environment provides a stable operating regime which permits precise process control which is highly repeatable. However, after a semiconductor wafer is processed it is removed from the vacuum environment, placed into an atmospheric transport container and subsequently delivered to the next process tool. Transitioning the semiconductor wafer between atmospheric and vacuum environments has been the traditional process method in the industry but recent advancements in device structures below the 22nm technology node are challenging the effectiveness of this method. Specifically, management of the semiconductor wafer exposure limits to oxygen and moisture at all times is now becoming standard practice to achieve desirable production yields.

The application of a mobile vacuum carrier to transport and store semiconductor wafers provides a contiguous vacuum environment between process platforms. The vacuum carrier utilizes a standard mechanical interface, or vacuum port, for docking to the process platform and is compatible with current factory automation systems. The vacuum port provides automatic loading/unloading of the vacuum carrier which includes dynamic pressure equalization between source and target environments. Typically, a vacuum carrier load/unload on the vacuum port is completed in <60 seconds on average. Preliminary experiments have demonstrated acceptable vacuum performance sustained in the carrier over prolonged durations (after 72 hours <3 Torr). Over the same period, exposure limits of oxygen and moisture within the vacuum carrier are within part-per-million ranges (66ppm and 349ppm, respectively). The reduction in exposure to environmental contaminants removes variability thus improving process quality and yield. In addition, a mobile vacuum environment can be used to connect discrete process platforms and create customized process flows without the semiconductor wafers ever leaving vacuum. This capability presents opportunities to develop new equipment architectures and unique semiconductor processes.

In summary, as device dimensions continue to shrink, wafer sensitivity to environmental contamination increases. This in turn drives the necessity for improved environmental control throughout the entire semiconductor process including transport and storage of the semiconductor wafers. For semiconductor manufacturers, the mobile vacuum environment provides the capability for endpoint-to-endpoint control of the wafer environment not only within critical process chambers but also while transferring them between process platforms.