Fundamental connection between hydrogen/deuterium desorption at silicon surfaces in ultrahigh vacuum and at oxide/silicon interfaces in metal–oxide–semiconductor devices

Abstract

The fundamental connection between electron stimulated desorption (ESD) of hydrogen (H)/deuterium (D) at silicon surfaces in ultrahigh vacuum and hot-carrier-stimulated desorption of H/D at the oxide/silicon interfaces in complementary metal–oxide–semiconductor (CMOS) devices is presented. The dependences of device degradation on carrier energy and current density were studied on two generations of CMOS devices. The results suggest that the interface degradation in long channel devices is primarily due to the desorption of H/D by high energy electrons through the direct electronic desorption mechanism, while the multiple vibrational heating mechanism becomes important for ESD of H/D in deep submicron devices. By measuring interface trap generation at various stressing conditions in large time scales, we also provide experimental evidence to show that, unlike the uniform energy distribution of Si–H on silicon surfaces, the disordered interface environment introduces a variation of Si–H bond strength at the interface.