Hydrogen-related influence of the metallization stack on characteristics and reliability of a trench gate oxide

摘要

We discuss influences of the metallization / passivation stack on the 30 nm thick gate oxide of a trench DMOS. A variation in the metallization stack directly influences the gate oxide lifetime, but also the transfer characteristics of the device and the interface trap density revealed by charge-pumping measurements. Surprisingly, a better anneal of the Si-SiO_2 interface and the bulk-oxide, resulting in a smaller measured interface-trap density on virgin wafers, implies a reduced GOX reliability. These effects are attributed to the release of reactive hydrogen from PECVD deposited silicon-nitride layers.