Stratus Automation
Conveyor-OHT “Hybrid” AMHS

Among the various automated material handling system (AMHS) providers in the market, Daifuku and Muratec of Japan stand out as the two most prominent AMHS providers for the semiconductor industry globally. Their Overhead Hoist Transport (OHT) system is renowned for directly accessing the load port of process tools, thereby nearly eliminating the need for human intervention for the vast majority of 300mm front-end fabs. On the other hand, Stratus Automation has provided roller conveyor-based AMHS for the same front-end wafer processing fabs for nearly two decades, which has been known as an economical yet high-throughput alternative to the OHT based AMHS. Stratus’s conveyor system’s only shortcoming was its inability to load/ unload the carrier directly to/from the process tools, thus requiring human-based loading at the final few meters of the carrier travel.

Stratus recently introduced “Hybrid AMHS” that combined the strength of conveyor and OHT. It takes advantage of the high throughput of conveyor for long-distance (inter-bay) traffic and uses OHT to enable direct loading/unloading to/from process tools along with the vast capacity of overhead storage.

Though the use of a 300mm wafer became the new standard since the early ‘90s, many organizations still use 200mm or even 150mm wafers for their IC fabrication. Many organizations also prefer a 200mm wafer for adequate efficiency and low cost of process tools.However, the wafer processing tools for these smaller wafers were originally designed for human loading of wafer carriers on the machine.

Stratus saw the market opportunity to automate the 200mm wafer fabrication process and developed its hybrid system around it. The company applied its own design in the OHT to load/unload wafer carriers to/from the wafer processing machine. Especially in older low ceiling fabs, it may be the only choice available to fully automate the transport and loading of wafer carriers.

Success Story of Stratus Hybrid AMHS

Stratus’s innovative material handling solution has helped many of its clients fully automate semiconductor fabrication facilities. In one instance, a Singaporean subsidiary of a major foundry had a 200mm wafer fab. The factory housed many types of process tools that required a customized automated loading system. To fully automate the wafer handling, the organization contracted Stratus. The company achieved this goal with such efficiency with the pilot contract that the client gave Stratus “supplier of the year” award. The subsidiary was so impressed with Stratus’ work that they switched to it after canceling a contract with a local AMHS provider and awarded all of the remaining phases to Stratus.

Stratus Automation is currently an SME that entertains projects with a typical contract size of 5-30 million USD. Its mission statement is ‘providing twice the throughput at half the price (of the competition).’ That is why it is quickly attracting the attention of numerous potential customers. Additionally, its agility and flexibility to accommodate the special needs of older wafer processing tools is making it a clear choice for the 200mm wafer AMHS.

The company has intentionally kept a low profile since its good reputation, and word of mouth alone kept them growing and operating at full capacity. However, since it has successfully expanded its operation in Penang Malaysia, it now wishes to change its policy and work with two to three additional major companies, with each consumer providing orders ranging from 10 to 30 million USD. The organization also obtained contracts from a China-based 300 mm fab operator interested in its AMHS solutions. The organization is likely to soon cross the $100 million mark in not more than three years with the current rate of growth.