Roth & Rau - Ortner

RFID Retrofit Solution for Wafer Carriers Bridges the Intralogistics Gap in Mature Semiconductor Factories

Articles | By Roth & Rau - Ortner | 08 July 2014
At the end of the process, the carrier content's monetary value can reach the equivalent of a luxury limousine. If a process carrier is fed to the wrong machine at the wrong time, or if the wrong recipe is started with this carrier, the product lot is worthless. At the end of the process, the carrier content's monetary value can reach the equivalent of a luxury limousine. If a process carrier is fed to the wrong machine at the wrong time, or if the wrong recipe is started with this carrier, the product lot is worthless. Photo: Roth & Rau - Ortner GmbH

Intralogistics in Chip Production

RFID is the Missing Link

Modern 300 mm semiconductor factories work fully automated and highly effective. In contrast to this, older 200 mm factories that were built in the 1990s or earlier are mainly based on manual intralogistics processes. A lot of efficiency potential for instance remains unexploited solely because there is a lack of secure identification to track the product carrier inside a factory, explains Ulrich Spannring, Sales Manager Roth & Rau – Ortner, in an interview with „RFID im Blick“. The company has developed an RFID retrofit solution for wafer carriers that bridges this gap and meets the high standards of clean rooms.

Ulrich Spannring, Sales Manager Roth & Rau – Ortner, in an interview with Dunja Kandel, „RFID im Blick“

Retrofitting of Wafer Carriers with RFID Tags as Cost-efficient Alternative

Whereas 300 mm factories are designed for RFID-based fully automated intralogistics, Wafer Carriers in 200 mm factories are often transported manually between the machines and the place where they are loaded and unloaded. The input of recipes for processing is a manual procedure, as well. Retrofitting with RFID enables automization in mature factories.

For this purpose, the subsequent equipment of wafer carriers with RFID is a cost-efficient option“, reports Ulrich Spannring. „New RFID-capable carriers cost 100 to 200 euros per unit. On average, a factory has 1,000 to 5,000 of such product carriers with a service life of around three to five years. Retrofitting saves 80 percent of the costs compared to a new carrier purchase. This is why factories are looking for a retrofitting opportunity, still: Affixing the transponder for usage in clean rooms is anything but trivial. The lowest contaminations endanger the product yield. The product carriers' geometry must not be changed, since their concept is tailor-made for the machines. Furthermore, the transponder must not interfere handling processes carried out by sorting robots.“ A solution thus had to meet the geometrical requirements and under any circumstances not result in wafer contamination.

Ultrasonic Tag Welding

In the process of retrofitting, the transponders are affixed to the carriers, that are made of polycarbonate or PEEK and carry 25 wafers each, using ultrasonic welding. Glass transponders with LF frequency are used. LF is a standard in the semiconductor industry (Picture: Roth & Rau – Ortner GmbH)In the process of retrofitting, the transponders are affixed to the carriers, that are made of polycarbonate or PEEK and carry 25 wafers each, using ultrasonic welding. Glass transponders with LF frequency are used. LF is a standard in the semiconductor industry (Picture: Roth & Rau – Ortner GmbH).
On the carrier, RFID turned out to be the most suitable way of identification. Affixing the transponders was the biggest challenge. „The production environment temperature of partially more than 100 degrees would repeatedly result in evaporations when adhesives are used. The result is contamination and the loss of production. Mechanical attachment using a clip would also lead to frictions and particle formation, which is a knockout criterion“, says Spannring. Ultrasonic welding eventually turned out to be the only solution. „We weld the transponder to the carrier, hermetically sealed by a transponder holder. It then complies exactly with the design offered by the supplier. That means we do not geometrically modify the carrier in any way. We create a welding seam that neither results in surface, nor mechanical alterations.

RFID as Enabler for Far Reaching Automation

At the moment, Roth & Rau – Ortner cooperates with many semiconductor manufacturers to test the solution in pilot projects: „Two of our partners have sucessfully carried out tests and want to equip their whole carrier stock with transponders“, Spannring reports. Many customers consider automating their factories, however the carriers were not machine readable. „In this regard we can help customers by making their carriers identifiable in the first step. In the second step we integrate the RFID readers and antennas into machines and storage places. Furthermore, we develop the software and take care of the connection to the MES as system integrator, always following the goal of enabling an automation solution in the factory, because RFID is an enabler for far reaching automation.“

Secure Process Control is only Possible with RFID

In Europe, there were still around 50 factories of different size that process on wafers with a diameter of 200 mm or less. Ulrich Spannring: „Larger factories have gradually integrated consistent RFID solutions. The rest of at least 50 percent barely have machine-readable carriers and continue to work with route cards. Here, RFID is the missing link: We also receive requests from low-wage countries in Asia. This clearly indicates that the RFID retrofitting solution is profitable. Product safety is the strongest argument: machine misloadings caused by wrong allocation of the lot to the recipe cause extremely high damage.“ The expert continues that time saving due to the elimination of searching processes was another factor that was taken into account for the ROI calculation by many customers. With a comprehensive RFID integration the location of the product lots was transparent any time.

Increasing Need for Automation in Large Laboratories

The retrofitting solution is specifically tailored to the semiconductor industry's target market. Spannring, however, also sees a growing need for material flow automation in other fields, such as the laboratory environment. „Laboratory operations in Europe have undergone a major change in the last few years. Modern large laboratories process 15,000 to 20,000 samples a day, coming from different sources, such as hospitals and doctors in private practice. In terms of throughput, these are industrial enterprises that strongly rely on handling this material flow.“

Last modified on Tuesday, 08 July 2014 09:44
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