Experimental evidence of Si–H bond energy variation at SiO2–Si interface

Abstract

The threshold energy barrier for hydrogen desorption from the SiO2–Si interface has been assumed to be the Si–H bond energy with the value of 3.6 eV. Based on the uniform Si–H bond energy and diffusion-limited degradation, the time-dependent hot-carrier degradation of metal–oxide–semiconductor (MOS) devices has been described by the so-called power law. In this letter, by investigating the degradation of submicron n-channel MOS devices at various stress conditions and over a large time scale (0.01–10000 s), we present experimental evidence that contradicts the uniform bond energy theory and supports the bond energy variation theory proposed recently by Hess and co-workers [Appl. Phys. Lett. 75, 3147 (1999); Physica B 272, 527 (1999)]. We find that, instead of a constant power factor of n=0.5 predicted by the uniform bond/diffusion-limited energy theory, n varies from ∼0.8 at the initial stress stage to ∼0.2 at the final stress stage consistent with the bond energy variation theory.