Acronym · Fab Ops, Yield & Metrology
FOUP (Front Opening Unified Pod)
The sealed plastic carrier that holds up to 25 300 mm wafers and mates to a tool's load port door, keeping wafers in a controlled mini-environment so the tool interior, not the whole fab, must be ultra-clean.
- Also known as
- Pod
- Type
- Acronym
- Domain
- Fab Ops, Yield & Metrology, Fab operations
Notes
FOUPs made ballroom-class-1 cleanrooms unnecessary at 300 mm and are standardised under SEMI E47.1.
Overview
A FOUP (front opening unified pod) is the sealed plastic carrier that holds a batch of 300 mm wafers, usually up to 25, and carries them between process tools, stockers and metrology tools in a fab. Its front door opens only when the pod is docked at a tool's load port, so the wafers stay in a small controlled environment instead of being exposed to the open cleanroom. FOUPs arrived with the first 300 mm tools in the mid-1990s.
How it works
A FOUP is a moulded shell with fixed wafer supports, spaced at a 10 mm pitch for 25 wafers, and a front door that seals against the shell. Coupling plates and interface holes on the pod locate it precisely on a load port and let automated transport pick it up. At the tool, the load port opens the door so that the tool's robot can reach the wafers from inside the equipment's own clean environment, then closes the pod again.
A fully loaded pod weighs several kilograms, so 300 mm fabs move FOUPs with automated material handling systems, such as overhead hoist transport running between tools and stockers. SEMI E84 defines the parallel I/O signals that coordinate each handoff between the transport system and a tool's load port. RFID tags or labels identify each FOUP to the factory's manufacturing execution system.
Materials and options matter. Entegris, for example, makes FOUP shells from ultrapure polycarbonate or carbon-filled barrier material, with optional anti-static shells and purge ports for clean gas, which fabs use to protect sensitive wafers between steps. A 13-slot format at wider pitch suits thin or bonded wafers, and related front opening shipping boxes carry wafers between sites.
Examples
- An overhead hoist vehicle lifting a FOUP from a lithography tool's load port and delivering it to an etch tool.
- A purged FOUP holding wafers between two process steps that are sensitive to exposure to fab air.
- A 13-slot FOUP used for thin or bonded wafers that need wider spacing.
- A load port reading a FOUP's RFID tag so that the factory system knows which lot has arrived.
Why it matters
FOUPs make the automated 300 mm fab practical: they protect wafers from particles and handling damage, allow the open cleanroom to be less strict than the tool interiors, and let robots and overhead vehicles do all the carrying. AMHS engineers, fab automation engineers, contamination control engineers and equipment engineers all work with them, and a contaminated pod can affect every wafer it holds.
Related terms
Part of the Fab Ops, Yield & Metrology glossary, with every term in the topic and the lifecycles, tools and standards that use them.
Where it appears on the Hub
Used on 5 pages of the Hub. In each group, the pages that mention it most come first.
Roles
Suggest an improvement
Suggest an improvement to this entry
A clearer definition, an example, a correction or a source an editor can check. Editors review every suggestion before the entry changes.
Last reviewed . Written by The Semiconductor Hub editorial team. The full glossary