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Keywords:

Science & Technology, Physical Sciences, Physics, Applied, Physics, CHEMICAL-VAPOR-DEPOSITION, TA2O5 FILMS, DEPENDENCE, LAYER, 01 Mathematical Sciences, 02 Physical Sciences, 09 Engineering, Applied Physics, 40 Engineering, 49 Mathematical sciences, 51 Physical sciences

Abstract:

The electrical characteristics of metal-oxide-semiconductor capacitors with SiON/Ta 2 O 5 gate dielectric stacks with thin Ta 2 O 5 layers (6-10 nm) are investigated. From the field and temperature dependence of the current of the gate stacks, it is shown that the main conduction mechanism at low bias is tunneling through the stack and that Poole-Frenkel conduction in the Ta 2 O 5 layer becomes important at larger bias and temperature. From the analysis of the data in the high voltage and temperature range, taking into account the field distribution in both layers, the refractive index n of Ta 2 O 5 and the energy level φ B of traps involved in Poole-Frenkel conduction are found to be 2.3 and 0.85 eV, respectively. It is also shown that the gate current density of the stack is reduced by one to three orders of magnitude as compared to SiO 2 layers with equivalent electrical thickness (2.5-3 nm). The temperature acceleration effect on the time-dependent dielectric breakdown is shown to be much reduced in the SiON/Ta 2 O 5 stack as compared to SiO 2 layers with equivalent electrical thickness. © 1999 American Institute of Physics.