The solar wafer "WSIC" system combines automated wafer cassetting with integrated laser measurement and high speed digital imagining technology to provide 100%, in process, wafer inspection. Solar wafer stacks are singulated and the individual wafers are cassetted at a process rate of 800-1000 wafers per hour. During the automatic cassetting process, three non-contact laser measurement systems collect thickness data, while high speed digital imagining analysis is used for defect detection on every wafer.
Wafers which exceed allowable thickness variation parameters or exhibit defects such as chipped and broken wafers are rejected, while wafers that pass the test criteria automatically continue into storage cassettes. Selected data, such as Average Thickness, Total Thickness Variation (TTV), and total numbers of a defect type, for each run is displayed on the operator interface screen. This system includes data download capability to a host system for process control and process improvement feedback. Preloaded wafer magazines are quickly and easily changed at the end of each production run. Full cassettes are automatically exchanged with empty cassettes via a cassette transfer and management sub-system.
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