Charge Trapping in Wafer Bonded MOS Structures

Wafer bonded MOS capacitors were investigated in order to study the electrical properties of bonded silicon dioxide layers. From CV measurements we estimated the amount of charge located at the bonded SiO2-SiO2 interface to be less than about 10¹¹ elementary charges per cm². We also found that the formation of a bonded SiO2-SiO2 interface did not affect the thermally grown Si-SiO2 interface. Pronounced negative charging at or close to the bonded SiO2-SiO2 interface was observed during Fowler-Nordheim charge injection. Reference samples, without bonded interfaces, did not exhibit the same magnitude of oxide charging.