Synopsis:
This module allows a user to perform a Root Cause Analysis for low yields at either Wafer Sort or Final Test. Users can correlate between Inline Fab data (PCM/WAT) and any other test data source loaded into yieldWerx.
Description:
Customers who want to comprehend correlations between different test/assembly manufacturing steps value the capability that the Cross Work Center Correlation module provides. It feeds an engineer’s commonality analysis, uncovers wafer test measurements that predict final test failures, and aids in determining likely root cause for a low yielding material.
With proper data alignment, engineers can have full traceability from wafer acceptance test (WAT) to final test data that enables correlating data measurements between one test step to another. The ability to fully trace each wafer lot and final test lot with their history of equipment enables engineers to consider equipment influences on performance metrics such as maximum frequency or IDDQ testing. When a statistical bin or yield limit is tripped at final test, engineers can identify all final test lots which have the same fab/wafer test history. These lots can be put on hold while the root cause for tripping the alert is determined. If it is fabrication related engineers/operators can decide to scrap the remaining lots or move ahead with testing and informing the product manager of the impact upon customer shipments.
This module provides fabless product engineers a facile means of demonstrating that the poor yield is due to foundry processing and not a test program issue. Foundry states- PROVE it, and this module enables you to provide that information. Product engineers can then send the specific wafer ids and lot ids back to the foundry for them to resolve, meanwhile, the contractual agreement between the foundry and fabless entities can be fulfilled.
Where applied:
- Wafer Probe
- Final Test
- Wafer Fab