By Rhea Wessel
Jan. 15, 2007—
Infineon Technologies, a producer of semiconductors, is using
radio frequency identification combined with ultrasound-based location-tracking technology to continuously oversee and better manage its production of silicon wafers, which the company uses to make integrated circuits (ICs).
Headquartered in Munich, Germany, Infineon is using a system called LotTrack, created by Switzerland-based
Intellion. LotTrack features battery-powered
RFID devices called DisTags, which Infineon has affixed to containers, or lot boxes, of wafers to track each lot's location. DisTags also feature no-power (bistable) display screens, which are automatically updated to provide instructions to employees working on the production lines. The DisTag battery can last for two years, according to Markus Dierkes, Intellion's CEO.
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Infineon's Hanspeter Fischer
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DisTag contains a
UHF (868 or 916 MHz) active
RFID tag made by
Identec Solutions that constantly communicates (via a proprietary
protocol) with Intellion-designed, ceiling-mounted antennas. Equipped with an ultrasound
sensor, the DisTag periodically receives signals sent by ultrasound emitters, also installed on the ceiling. The tag calculates the time-of-flight for the ultrasound signals it receives, storing these values in its
memory. RFID interrogators
read this data from the tag and transfer it to a server that calculates the location of the lot to within 0.5 meters.
At the start of production, an operator clips a DisTag to a lot box, which is labeled with an Infineon 13.56 MHz
ISO 156693
passive tag encoded with a unique ID number. The worker then uses an Intellion-designed handheld 13.56 MHz RFID
reader to positively identify that the correct lot box is being processed. In a second, separate RFID application installed by Infineon, RFID antennas on production machines read the passive MHz ISO 156693 RFID tag sewn into the wristband of the operator's clean-room suits as the worker approaches a machine. When the machine positively identifies the worker, it displays a confirmation. As the system moves the lot box of wafers down the production line and tracks its movements, the LotTrack server updates the DisTag display with instructions corresponding to the lot box's location.
A third RFID application, also part of Infineon's "integrated fab" (iFAB) concept—
fab being short for the German word
Fabrik, which means 'factory'—identifies wafer cassettes inserted into the machines. In the cassette ID system, also installed by Infineon without the help of Intellion, antennas on each piece of production equipment identify cassettes and confirm that the right process is being performed on the right lot. This system, in a sense, double-checks that workers have placed the right lot box on the right machine, as instructed on the DisTag. Before Infineon installed these antenna readers, this confirmation process was done manually.