Charge trapping and breakdown mechanism in HfAlO/TaN gate stack analyzed using carrier separation

Charge trapping and breakdown mechanism in p- and n-channel MOSFETs with an HfAl/sub x/O/sub y/ and TaN metal electrode are investigated. Using carrier separation measurement technique, it is possible to clearly distinguish two different breakdown mechanisms: a high-K bulk initiated and an interfacial layer initiated breakdown. A model of charge trapping at different spatial locations in HfAl/sub x/O/sub y/ with a TaN gate structure is proposed to explain the polarity dependence of charge trapping characteristics and breakdown mechanisms.