FOUP

FOUP is an acronym for Front Opening Unified Pod.

It is a specialised plastic enclosure designed to hold silicon wafers securely and safely in a controlled environment, and to allow the wafers to be removed for processing or measurement by tools equipped with appropriate load ports and robotic handling systems.

FOUPs began to appear along with the first 300mm wafer processing tools in the mid 1990s. The size of the wafers and their comparative lack of rigidity meant that SMIF was not a viable technology. FOUPs were designed with the constraints of 300mm in mind, with the removable cassette being replaced by fins in the FOUP which hold the wafers in place, and the bottom opening door being replaced by a front opening door to allow robot handling mechanisms to access the wafers directly from the FOUP. The weight of a fully loaded 25 wafer FOUP at around 9 kilograms means that automated material handling systems are essential for all but the smallest of fabrication plants.

Each FOUP has various coupling plates, pins and holes to allow the FOUP to be located on a load port, and to be manipulated by the AMHS (Automated Material Handling System). FOUPs may also contain RF tags that allow them to be identified by readers on tools, in the AMHS etc.