Overhead Hoist Transport (OHT) is a key transport unit within an Automated Material Handling System (AMHS), consisting of ceiling-mounted tracks and autonomous transport vehicles. Operating beneath these elevated tracks, OHT systems maximize the use of vertical space, eliminating the need for floor-based transport and creating a more efficient layout within FAB and cleanroom environments.
Each OHT vehicle travels along the overhead rail network and is equipped with a precision-controlled hoisting mechanism. Upon reaching its destination, the system uses a robotic arm to automatically pick and place carriers such as FOUPs directly at process equipment or stockers, enabling seamless “tool-to-tool” transfer without intermediate handling.
Designed for high-speed, stable, and contamination-controlled transport, OHT systems play a critical role in modern semiconductor manufacturing by improving material flow, reducing manual intervention, and supporting fully automated production environments.
