Katsuyuki Sekine

Highly reliable ultrathin silicon oxide film formation at low temperature by oxygen radical generated in high-density krypton plasma

This paper focuses attention on electrical properties of silicon oxide films grown by oxygen radical generated in Kr/O/sub 2/ mixed high-density microwave-excited plasma at 400/spl deg/C. They represent high growth rate, low activation energy, high dielectric strength, high charge-to-breakdown, and low interface trap density and bulk charge enough to replace thermally grown silicon oxide.

Advantage of radical oxidation for improving reliability of ultra-thin gate oxide

This paper focuses attention on the advantage of oxygen radical oxidation by a microwave-excited high-density Kr/O/sub 2/ plasma for improving the disadvantages of conventional thermal oxidation processes using H/sub 2/O and/or O/sub 2/ molecules, and demonstrates that the Kr/O/sub 2/ plasma oxidation process can improve the thickness variation on shallow-trench isolation and integrity of silicon oxide not only on the [100] surface but also on the [111] surface compared to those of conventional thermal oxidation processes.

Silicon nitride film growth for advanced gate dielectric at low temperature employing high-density and low-energy ion bombardment

Direct nitridation of silicon surface can be realized at a temperature as low as 430 °C by using high-density plasma above 1012 cm−3 featuring low ion bombardment energy below 7 eV. This study shows that stoichiometric silicon nitride can be obtained for the first time at a temperature of 400 °C by precise control of the nitrogen partial pressure to generate N2+ in the plasma. Moreover, hysteresis in the capacitance–voltage data that has been attributed to charge traps in silicon nitride film can be reduced dramatically by adding hydrogen to Ar/N2 plasma for terminating dangling bonds with hydrogen. The dielectric strength of silicon nitride films is nearly equivalent to those of thermally grown silicon nitride and silicon oxide. The leakage current of silicon nitride film is dramatically reduced compared to that of thermally grown silicon oxide even if their equivalent thicknesses are equal. The silicon nitride films have almost no stress-induced leakage current and very little trap generation even in hi...

Highly robust ultrathin silicon nitride films grown at low-temperature by microwave-excitation high-density plasma for giga scale integration

This paper focuses attention on electrical properties of ultra-thin silicon nitride films grown by radial line slot antenna high-density plasma system at a temperature of 400/spl deg/C as an advanced gate dielectric film. The results show low density of interface trap and bulk charge, lower leakage current than jet vapor deposition silicon nitride and thermally grown silicon oxide with same equivalent oxide thickness. Furthermore, they represent high breakdown field intensity, almost no stress-induced leakage current, very little trap generation even in high-field stress, and excellent resistance to boron penetration and oxidation.

Low-Temperature Formation of Silicon Nitride Film by Direct Nitridation Employing High-Density and Low-Energy Ion Bombardment

High-integrity silicon nitride films can be obtained at a temperature of 400°C using a newly developed high-density (>1012 cm-3) plasma characterized by low ion bombardment energies of below 7 eV. It was found for the first time that stoichiometric silicon nitride can be formed at a temperature of 400°C by precise control of nitrogen partial pressure to generate N2+ in plasma. The growth rate and the electrical properties of this silicon nitride are similar to those of thermally grown nitride. Moreover, hysteresis of the C–V curve attributed to charge traps in the silicon nitride film disappeared with the addition of hydrogen to Ar/N2 plasma, and the leakage current of the nitride film was decreased dramatically by irradiating in Ar/N2/H2 plasma after Ar/N2 plasma nitridation. These technologies are very promising for fabricating feature metal substrate silicon-on-insulator (SOI) devices and silicon nitride gate metal-insulator-semiconductor field effect transistors (MISFETs).

Effects of nitrogen concentration and post-treatment on reliability of HfSiON gate dielectrics in inversion states

We have studied the effects of nitrogen concentration ([N]=N/(Hf+Si+O+N)) in HfSiON films and post-nitridation annealing (PNA) conditions on the reliability of metal oxide semiconductor field effect transistors (MOSFETs) with HfSiON gate dielectrics in inversion states with constant voltage stress. In nMOS case, higher [N] and lower PNA temperatures are effective to reduce stress induced leakage current (SILC). SILC is related to crystallinity in HfSiON films. On the other hand, only small SILCs were observed in pMOSs, and the currents were independent of [N] and PNA temperatures without regard to crystallinity in the HfSiON films. Differences in SILC behavior between nMOS and pMOS are related to the electron transport mechanism. It is thought that SILC was generated by increasing positive oxygen vacancies whose energy level is near the conduction band edge of HfSiON. Since electrons in pMOS move through the deep trap level, their transit is independent of positive oxygen vacancies. For highly reliable HfSiON gate films, it is important to form homogeneous and amorphous HfSiON films.

High-integrity ultra-thin silicon nitride film grown at low temperature for extending scaling limit of gate dielectric

This paper focuses attention on the electrical properties of ultra-thin silicon nitride films grown by the radial line slot antenna (RLSA) high-density plasma system at 400/spl deg/C as an advanced gate dielectric film. The results show low interface trap and bulk charge density, lower leakage current than jet vapor deposition (JVD) silicon nitride and thermally grown silicon oxide with same equivalent oxide thickness (EOT), high breakdown field intensity, almost no stress-induced leakage current, and very little trap generation, even under high-field stress.

Influence of Traps and Carriers on Reliability in HfSiON/

The influence of traps and current on the degradation in HfSiON has been studied. Different characteristics of activation energy for TDDB between thick and thin HfSiON, where the Poole Frenkel (PF) and tunnel currents mainly flow, respectively, were observed in the same temperature range. It was indicated that the current could promote the breakdown in HfSiON. Furthermore, we investigated the correlation between pre-existing traps and trap generation in HfSiON/SiO2 stacks with fluorine incorporation. It was found that the nature of generated traps correspond to that of pre-existing traps. From these results, it was considered that the interaction between traps and carriers causes the degradation in HfSiON.

\hbox{SiO}_{2}

We fabricated for the first time, extremely low-leakage TiN single metal gate complementary metal-oxide-semiconductor field-effect transistors (CMOSFETs) for low-standby-power application by utilizing plasma oxidation and plasma nitridation in gate dielectric formation. The drive current and the subthreshold leakage current of the pMOSFET at a power supply voltage of 1.2 V are 172 µA/µm and 2.3 pA/µm, respectively. The gate leakage current was successfully suppressed to below 1 pA/µm at Vg=-1.2 V.

Stacks

We have demonstrated stacked HfSiON gate dielectrics with a low-Hf-concentration [Hf/(Hf+Si)=6%] cap (LHC) layer. For fabricating the LHC layer, diethylsilane is more effective due to its decomposition characteristics being better than those of conventional amine-based precursors. The stacked structures exhibit improved mobility, the suppression of Vth shift, superior negative bias temperature instability (NBTI), and positive bias temperature instability (PBTI) reliability for complementary metal–oxide–semiconductor field-effect transistors (CMOSFETs), while maintaining low gate leakage currents. The mobility improvement is due to the superior control of nitrogen atoms, and the superior threshold voltage control and long-term reliability of the film are mainly due to the suppression of the positive oxygen vacancy (VO2+) formation related to carrier traps. These results were supported by the results of first-principles calculation.