Experimental evidence of inelastic tunneling in stress-induced leakage current

We propose a new experimental technique to study the transport properties o f stress-induced leakage current (SILC), Based on the carrier separation me asurement for p-channel MOSFET's, the quantum yield of impact ionization fo r electrons involved in the SILC process is evaluated directly from the cha nge in the source and gate currents of p-MOSFET's before and after stressin g. Since the relationship between the electron energy and the quantum yield is established for direct and FN tunneling currents, the electron energy o f electrons involved in the SILC process can be determined from the quantum yield, The results reveal that the measured energy of electrons in the SIL C process is lower roughly by 1.5 eV than the energy expected in the elasti c tunneling process. Trap-assisted inelastic tunneling model is proposed as a conduction mechani sm of SILC accompanied with the energy relaxation, It is shown, through the evaluation of the substrate hole current in n-channel MOSFET's, that the c ontribution of trap-assisted valence electron tunneling, another possible m echanism to explain the energy relaxation, to SILC is small.