Measurements of hydrogen redistribution in hot electron injection of MOS capacitors

Redistribution of hydrogen caused by hot electron injection has been studied in large Al-gate capacitors using internal photoemission followed by hydrogen depth profiling with the 15N nuclear reaction. A large peak of hydrogen (nearly 1015 at./cm2) at the Al/SiO2 interface due to a hydrated layer on the surface of the SiO2 was found to act as a source of hydrogen during the photoinjection. A small fraction of the hydrogen released from this peak was found to be re-trapped near the Si/SiO2 interface if a field of >1 MV/cm was applied to the SiO2 during the injection. Up to 2×1014 atoms/cm2 of hydrogen were found to be trapped at this interface for injected fluences up to 5 C/ cm2. These results are discussed in terms of current models of interface state generation involving hydrogen.