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Semiconductor Manufacturers offering a broad and complex spectrum of products face the challenge to implement a flexible and transparent production process including dedicated production logistics.
Managing Wafer Production
European facilities producing custom chips (mass production is left to Asian facilities) have to handle many differing, small lots, e.g. one facility manages around 750 products in 400 production steps for each product using 600 different tools and machinery scattered in multiple buildings. The challenge is on the one hand to cope with many changes of the work-flow and on the other reduce idle times of machinery as well as production errors due to the highly valuable raw material.
Tracking wafers along their process cycle in the fab
Parts of the solution
Ubisense tags are mounted on either cassettes or boxes and on the metal carts used for wafer transportation. Tags are allocated the Wafer ID’s using Ubisense API’s which prepare an easy interface to MES and ERP. Each cassette or box is automatically allocated the cart it was put in using spatial context of the Ubisense Software Platform.
The full solution to manage wafers that is beyond the basic knowledge of the wafer’s location is enhancing the possibilities for managing wafer production:
Real-time location tracking reduces searching time for wafers. At the control console of the MES the next job is indicated. This includes the cassette/box ID to process as well as a map showing the location of the individual cassette/box. In addition the number of the cart it was put in is also given. The tag attached to the individual cassette/box will flash and buzz so that it can easily be detected on the cart
Processing errors Automated alert if a wafer gets to a workstation in the incorrect sequence. Workstations have declared a virtual buffer zone around them. If a tag approaches the station (i.e. it is inside the buffer zone longer than e.g. 5 sec) which is not allocated the cassette/box of the following job an alert is raised at the control console of the MES.
Excessive Cycle times
Long dwell-time at a single station causes an alert which escalates over time. If a tag is inside the workstations buffer zone longer than a defined max dwell-time for that specific station e.g. 8 min an alert is raised at the control console of the MES.
Additional benefit is gained by tracking personnel inside the production area: