Process Monitoring for Nitride Dielectric Defect Density
A U T H O R / C R E D I T S
John Scarpulla, Keang Kho, and Scott Olson
TRW RF Products Center Redondo Beach, CA
A B S T R A C T
We have implemented a process monitor for defects in the silicon nitride deposition sub-process of a GaAs PHEMT fab line. The nitride is used as the dielectric in MIMCAPs (metal-insulator-metal capacitors). The defect monitor is based upon ramped breakdown testing of test capacitors on each wafer. In order to interpret the ramped breakdown data, the TDDB theory was utilized, suitably modified for the silicon nitride dielectric. Six months of process monitoring was carried out and an upper control limit established for the nitride defect density.