Experimental observation of conductance transients in Al/SiNx:H/Si metal-insulator-semiconductor structures

Abstract

Room temperature conductance transients in the SiN x :H/Si interface are reported. Silicon nitride thin films were directly deposited on silicon by the low temperature electron-cyclotron-resonance plasma method. The shape of the conductance transients varies with the frequency at which they are obtained. This behavior is explained in terms of a disorder-induced gap-state continuum model for the interfacial defects. A perfect agreement between experiment and theory is obtained proving the validity of the model. © 1997 American Institute of Physics. ͓S0003-6951͑97͒03732-7͔Presently, ultrathin silicon dioxide gates ͑30-40 Å͒ are required as a consequence of the reduction in the ultralargescale-integration ͑ULSI͒ silicon device dimensions. On the other hand, silicon nitride, Si 3 N 4 , has been successfully used as an insulator with different III-V semiconductors. Two important properties of silicon nitride ͑Si 3 N 4 ͒ make it a candidate to substitute silicon dioxide, SiO 2 , in ultrathin dielectric structures: silicon nitride has a higher dielectric constant and exhibits a better performance as a diffusion barrier than silicon dioxide. Nevertheless, the interface between Si 3 N 4 and Si is not as well known as the SiO 2 /Si interface and significantly higher densities of interfacial states are always displayed by the silicon nitride/silicon structure.In this letter we report for the first time the existence of conductance transients in Al/Si 3 N 4 /Si structures. As we show later, this behavior is related to the existence of a spatial distribution of interface states. We use metal-insulatorsemiconductor ͑MIS͒ diodes in which a 550-Å-thick SiN x :H film was directly deposited on ͗100͘ n-type silicon by electron-cyclotron-resonance ͑ECR͒ plasma at 200°C. Silicon nitride films have been fabricated with a wide composition range 1 from Si-rich to near stoichiometric and N-rich films. For compositions far from the stoichiometry the hydrogen content increases and the number of electrically active defects in the film increases due to the distortion in bonds induced by hydrogen, 2 in spite of the dangling bond saturation that it produces. In a previous work 3 we have proved by capacitance-voltage ͑C-V͒ and deep-level transient spectroscopy ͑DLTS͒ studies that the electrical properties of these films are closely related to hydrogen content. We observed hysteresis phenomena in the C-V curves. This behavior has been previously reported by Lau et al. 4 and may be understood by the defect model suggested by Hasegawa et al. 5,6 These authors proposed that the interface states are distributed both in energy and in space. This distribution is called disorder-induced gap-state ͑DIGS͒ continuum. Emission and capture of free electrons by states located far from the interface can occur by mean of tunneling mechanisms.7 When bias varies from inversion to accumulation, electrons in the semiconductor conduction band are captured by emptied interface states, whereas when moving in the opposite direction electrons are emitted from filled ...

A detailed analysis of the energy levels configuration existing in the band gap of supersaturated silicon with titanium for photovoltaic applications

“…27,28 This capability is used here to study supersaturated silicon substrates. The variation with the frequency and temperature of the conductance transients caused by the bias pulses gives information about the energy levels distribution in the band gap.…”

Electrical Characterization of High-K Dielectric Gates for Microelectronic Devices

“…All gate dielectrics exhibit conductance transients in MIS structures when are driven from deep to weak inversion [32]. This behavior is explained in terms of disorder-induced gap states (DIGS) continuum model suggested by Hasegawa et al [33].…”

Electrical characterization of electron cyclotron resonance deposited silicon nitride dual layer for enhanced Al/SiNx:H/InP metal–insulator–semiconductor structures fabrication

“…This behavior agrees with the temporal evolution of the conductance measurement proposed in our previous work. 31 According to the explanation suggested in that work, only the decreasing transients provide reliable information about the interface states profile. Then, we focus our attention on transients measured at a frequency of 81 kHz.…”

“…In a previous work, 31 we have proposed and described in detail the conductance transients method. Room temperature conductance transients are obtained when pulses that drive MIS structures from deep to weak inversion are applied.…”