User:Ismith/Automated Material Handling System

An Automated Material Handling System is a system that controls the storage and transportation of silicon wafers within FOUPs in a wafer fabrication plant. It's job is to ensure that the right FOUP is delivered to the right tool at the right time. It does this by using control software to pilot the transport of the FOUPs between tools and to and from storage locations.

A typical AMHS is made up of several components:


 * Rail system
 * Stockers
 * Output stations
 * Vehicles
 * Control software

Each of these must work together so that the system as a whole functions properly.

Rail System
The system of tracks is mounted overhead so that it does take up space otherwise needed for fab equipment. This requires that fabs are built with sufficient headroom to accommodate the tracks and vehicles, and it can make it impossible to retro-fit transport systems into older fabs that were not designed with them in mind.

In order to be able to deliver a FOUP directly to a tool the rail must pass directly above the tool's load port, a constraint that makes it difficult in practice to install the transport system before the tools themselves have been installed.

The rail system must

Control Software
Each of these is tailored to its operating environment.

Material handling systems have two modes of operation:


 * Interbay
 * Intrabay

A wafer fab may also have separate transport systems serving different areas with stations to transfer FOUPs between the two, for example a high speed system to transport FOUPs over longer distances and a lower speed system for local transport.