Charging Phenomena at the Interface Between High-k Dielectrics and SiOx Interlayers, Journal of Telecommunications and Information Technology, 2010, nr 1

The transition regions of GdSiO/SiOx and HfO2/SiOx interfaces have been studied with the high-k layers deposited on silicon substrates. The existence of transition regions was verified by medium energy ion scattering (MEIS) data and transmission electron microscopy (TEM). From measurements of thermally stimulated current (TSC), electron states were found in the transition region of the HfO2/SiOx structures, exhibiting instability attributed to the flexible structural molecular network expected to surround the trap volumes. The investigations were focused especially on whether the trap states belong to an agglomeration consisting of a single charge polarity or of a dipole constellation. We found that flat-band voltage shifts of MOS structures, that reach constant values for increasing oxide thickness, cannot be taken as unique evidence for the existence of dipole layers

Charge carrier traffic at interfaces in nanoeletronic structures

This thesis describes investigations in relation to the search for materials with high dielectric constant, k, for future CMOS transistors. The most elementary quantities to be considered are k-value and energy band offsets between the dielectric and the silicon crystal on which it is deposited. Empirical relations for these two quantities are presented demonstrating that only a few dielectrics investigated up to now have properties providing the basic demands in the development of CMOS technology.Process development was done to deposit HfO2, Pr2O3 and HfPrO on silicon by reactive sputtering in order to fabricate MOS capacitors. Electrical properties of these oxides were investigated by employing different techniques such as capacitance-voltage (C-V), current-voltage (I-V), capacitance frequency spectroscopy, stepped C-V, multiparameter admittance spectroscopy (MPAS) and thermally stimulated current (TSC).A capacitance frequency spectroscopy technique was developed to investigate electron capture cross sections of the interface states at high-k/Si interface from experimental results. It is found that capture cross sections of electron states at this interface are thermally activated and exponentially depend on energy depth of interface states in the silicon bandgap. These processes indicate that the capture mechanism is governed by multiphonon.MPAS a diagnostic tool developed from the conductance method to deliver more information regarding charge carrier states in semiconductor structures. Using this technique on HfO2/Si interface, two different types of interface states with different capture mechanisms were found.An interlayer of SiOx is found between the silicon crystal and HfO2 in TEM pictures. A transition region, which is expected to have strong concentration gradients, exists between SiOx and HfO2. This region shows an unstable atomic arrangement and contains charge carrier traps. These traps exchange electrons with the conduction band of the silicon crystal through a combined thermal-tunneling mechanism

Charge carrier traffic at interfaces in nanoeletronic structures

This thesis describes investigations in relation to the search for materials with high dielectric constant, k, for future CMOS transistors. The most elementary quantities to be considered are k-value and energy band offsets between the dielectric and the silicon crystal on which it is deposited. Empirical relations for these two quantities are presented demonstrating that only a few dielectrics investigated up to now have properties providing the basic demands in the development of CMOS technology.Process development was done to deposit HfO2, Pr2O3 and HfPrO on silicon by reactive sputtering in order to fabricate MOS capacitors. Electrical properties of these oxides were investigated by employing different techniques such as capacitance-voltage (C-V), current-voltage (I-V), capacitance frequency spectroscopy, stepped C-V, multiparameter admittance spectroscopy (MPAS) and thermally stimulated current (TSC).A capacitance frequency spectroscopy technique was developed to investigate electron capture cross sections of the interface states at high-k/Si interface from experimental results. It is found that capture cross sections of electron states at this interface are thermally activated and exponentially depend on energy depth of interface states in the silicon bandgap. These processes indicate that the capture mechanism is governed by multiphonon.MPAS a diagnostic tool developed from the conductance method to deliver more information regarding charge carrier states in semiconductor structures. Using this technique on HfO2/Si interface, two different types of interface states with different capture mechanisms were found.An interlayer of SiOx is found between the silicon crystal and HfO2 in TEM pictures. A transition region, which is expected to have strong concentration gradients, exists between SiOx and HfO2. This region shows an unstable atomic arrangement and contains charge carrier traps. These traps exchange electrons with the conduction band of the silicon crystal through a combined thermal-tunneling mechanism

Multiparameter admittance spectroscopy (Invited)

Multiparameter admittance spectroscopy is described for investigating interface state properties of metal-oxide-semiconductor structures. In the conductance mode of this method, it allows for obtaining three-dimensional or contour plots of conductance data which reveal the mechanisms for capture of charge carriers into the interface states

Multiparameter admittance spectroscopy (Invited)

Multiparameter admittance spectroscopy is described for investigating interface state properties of metal-oxide-semiconductor structures. In the conductance mode of this method, it allows for obtaining three-dimensional or contour plots of conductance data which reveal the mechanisms for capture of charge carriers into the interface states

Multiparameter admittance spectroscopy for metal-oxide-semiconductor systems

Admittance spectroscopy is extended for measuring capacitance and conductance on metal-oxide-semiconductor (MOS) structures as a function of gate voltage, frequency, and temperature. An automatic setup has been designed for collecting data along these dimensions in one measurement cycle. The theory for admittance spectroscopy has been developed by starting from basic charge carrier statistics. Using numerical integration of energy dependent parameters instead of the commonly used analytical solution, conductance dispersion curves are obtained which do not need to be adjusted by assuming lateral surface potential variations at the oxide-semiconductor interface. Also, we find that interface state densities extracted by using traditional methods are four times lower than those obtained by using our theory. Experimental data presented in three-dimensional plots are compared with theoretical calculations, revealing the possibilities and limitations of the conductance method

Multiparameter Admittance Spectroscopy as a Diagnostic Tool for Interface States at Oxide/Semiconductor Interfaces

Multiparameter admittance spectroscopy (MPAS) measurements have been performed on Al/HfO2/SiOx/Si structures before and after post metallization annealing (PMA). Contour plots of conductance data as a function of the logarithm of inverted signal frequency and applied voltage as obtained by MPAS are compared with standard capacitance versus voltage (C–V) data demonstrating the advantage of MPAS as a diagnostic tool. MPAS reveals more detailed properties of oxide/semiconductor interface states and renders measured data for better perceptiveness