E′ centers and leakage currents in the gate oxides of metal oxide silicon devices

We have made electron spin resonance and current density versus voltage measurements on a variety of thin SiO2 films on silicon. In some of the films we have generated fairly high (greater than or equal to 10(18) cm(3)) densities of neutral E' centers near the Si/SiO2 interface. Neutral E' centers are paramagnetic defects in which an unpaired electron resides in a high p-character wave function primarily located on a silicon atom bonded to three oxygen atoms. We find that the generation of these centers is consistently accompanied by the generation of large leakage currents in the oxide. We also find that the annihilation of these E' centers by a low temperature (200 degrees C) anneal in air is consistently accompanied by the annihilation of the large leakage currents. Many investigations have established that high electric field stressing creates leakage currents in thin oxide films on silicon. Studies of at least two independent groups have also established that high electric field stressing generates significant E' density within the stressed oxides. Our study demonstrates a strong link between E' center density and oxide leakage currents. Our results, combined with the results of the earlier aforementioned studies, strongly indicate an important role for E' centers in stress induced leakage currents. These leakage currents are a fundamental problem in the very thin SiO2 films on silicon utilized in present day metal oxide silicon devices. (C) 2000 American Vacuum Society. [S0734-211X(00)08304-9].