Global silicon chip manufacturer TowerJazz not only produces high-memory radio frequency identification chips used by the aerospace industry, but it is now employing Wi-Fi-based RFID technology at one of its own fabrication facilities to track work in progress. The solution, deployed at TowerJazz’s fabrication plant in Newport Beach, Calif., consists of AeroScout‘s battery-powered Wi-Fi tags, exciters to better pinpoint a tag’s location, and software to determine at which workstation or on what rack wafers are located during the manufacturing process, based on read events, and to then share that information with the company’s dispatch-management system. The system is being installed in various phases, with the first phase (identifying manufacturing station locations) installed in 2011 and a second phase (identifying racks on which carriers filled with wafers are temporarily parked) in late 2012. Light-emitting diodes (LEDs) are now being installed to indicate visually when a batch of wafers has arrived at a specific workstation.
TowerJazz provides integrated circuits to many of the world’s semiconductor companies. Among its customers is Tego Inc., for which TowerJazz manufactures the high-memory EPC Gen 2 passive ultrahigh-frequency (UHF) RFID TegoChip, used by the aerospace industry to track pressurized and non-pressurized parts and components. TowerJazz operates three manufacturing facilities: one in Israel (the facility at which the RFID chips are produced), another in Japan and the third in California.
In addition to fabricating the TegoChip, TowerJazz manufactures dozens of types of ICs daily, in different lots. Every lot, consisting of 25 wafers manufactured to fill a specific order, can pass through hundreds of steps unique to that lot, such as etching and polishing. Each step is accomplished at a series of workstations prior to the lot being shipped to a customer according to a particular order. At the stations, staff members must complete a step in the manufacturing process using the tools specific to that location, and then move the wafers to their next step for the particular lot and order they are intended to fill.
The process can be time-consuming, says Dale Bogan, TowerJazz’s production director, as operators manually determine the proper dispatch—that is, to which station a lot must be moved next, in order to ensure that it undergoes the proper procedures and does not fall behind other orders that may have been placed after it. “Our production line is not linear,” he explains, “so a lot is dispatched to the next step, which could be anywhere in the production line.”
While the company sought to improve the efficiency of its manual dispatch system for assigning manufacturing processes, Bogan says, the cost of installing a completely automated delivery system failed to provide the return on investment that the firm would require. Therefore, TowerJazz opted to continue utilizing the existing dispatch system—in which a lot order was received and specific stations were assigned to manufacture those wafers—while employing RFID read data to ensure that the properly assigned process was being carried out. The company determined that adding RFID technology to its manufacturing processes could improve efficiency and increase on-time delivery.
TowerJazz has attached an AeroScout T2 tag to each lot box in which wafers are placed during the fabrication process. As an order is received, that tag’s unique ID number is linked to the order description in TowerJazz’s existing real-time dispatch (RTD) system. The tag then transmits its ID to Wi-Fi nodes installed throughout the facility.
The company also installed AeroScout EX2000B and EX3210 exciters at every workstation’s entrance and exit, in order to track each lot box’s progress. As a lot is transported to a station, the exciter at that location transmits a low-frequency wakeup signal to the tag, which then transmits its own unique identifier, along with the exciter’s ID, to local area Wi-Fi access points.
AeroScout software determines that lot’s location at a specific station and forwards that information to the company’s dispatch software, thereby updating the lot’s status. At any time during manufacturing, Bogan says, TowerJazz “can review the history of physical lot location” for each lot in the process of being manufactured. “The dispatch data is real-time and more accurate” than the manual method, he states.
Once a lot’s fabrication process is complete, the wafers are removed from the lot box and are shipped to a customer. The lot box and the RFID tag attached to it, meanwhile, are reused on another order.
Since the system’s installation in July 2011, Bogan reports, TowerJazz has been able to know where each lot is located at any given time, and determine when a particular lot has fallen behind or been sent to the wrong station. “We have gained a very significant improvement in operator efficiency,” he says. Consequently, he adds, “We were able to reduce our labor cost and improve our on-schedule delivery.”
During phase II, which was completed in late 2012, TowerJazz installed exciters on racks situated between workstations, allowing it to identify when a lot is placed on a rack while waiting for the next assigned workstation to become available. The company now has more than 100 exciters in place on its racks, as well as at workstation entrances and exits.
For the next phase, the firm is in the process of installing visual location functionality that uses the RFID data to identify when a lot tag comes within range of a workstation’s exciter. When that occurs, an LED will illuminate, thereby alerting employees to the lot’s presence at that station.