Strained Si NMOS Research Articles

Effects of Total Dose Radiation on Single Event Effect of the Uniaxial Strained Si Nano NMOSFET

The effect of total dose radiation on the single event effect of uniaxial strained Si Nano channel metal oxide semiconductor field effect transistor (NMOSFET) was studied by TCAD simulation. By comparing the experimental results, the TCAD simulation model of the 50 nm strained Si NMOS device is established. The model is used to simulate the off-state single event effect (V ds = 0.05) of NMOSFET under the total dose radiation. The results show that total dose radiation increases the body potential of NMOSFET devices and intensifies the single event transient process of NMOSFET devices. The transient current increases by 4.88% and the drain charge increases by 29.15% under the total dose of 2KGy, which indicates that the effect of total dose radiation on the single event effect is the main factor affecting the collection of drain charge. Therefore, the experimental results and the established model provide good reference for the study of irradiation reliability of the uniaxial strained Si Nano NMOSFET and the application of strained integrated circuits.

New Study on Experimental and Theoretical Mobility Sorts for Crystal Planes and Orientations of Small-Sized Uniaxial Strained Si NMOS Channel

New Study on Experimental and Theoretical Mobility Sorts for Crystal Planes and Orientations of Small-Sized Uniaxial Strained Si NMOS Channel

Study on hot carriers effect of uniaxial strained si nmos

The hot carrier effect of strained Si MOS is more significant than that of bulk Si MOS. Based on the study of the mechanism of hot carrier effect in uniaxial strained Si MOS, the factors affecting the hot carrier effect of uniaxial strain Si MOS and the effect on the electrical characteristics of the device are analyzed. The models of hot carrier collision ionization rate, interface state and threshold voltage degradation of uniaxial strain Si NMOS devices are established. The simulation results show that the threshold voltage shift is proportional to the interface state. When the interface state reached 1E8, the threshold voltage began to drift significantly. And reaching 1E12, the interface state reached saturation. With the increase of stress time, the shift of threshold voltage is decreasing.

A Novel Mobility Enhancement in Uniaxial Strained Si nMOS

A Novel Mobility Enhancement in Uniaxial Strained Si nMOS

The E-k Relations of Inversion Layer Sub-Band in Biaxially Strained Si nMOS

The E-<i>k</i> Relations of Inversion Layer Sub-Band in Biaxially Strained Si nMOS

Uniaxial Stress Induced Electron Mobility Enhancement in Silicon

The conduction band structure of Si under uniaxial [100] stress is investigated by using the two band k·p perturbation theory. The conduction band parameters, including the conduction band minimum energy shift, split and electron effective mass change are quantitative described. Based on these band parameters, uniaxial stress induced electron mobility enhancment is systematically studied through Boltzmann transport theory. The results show that, when uniaxial [100] stress is applied to Si crystal, a gain of more than 50 % in electron mobility can be obtained. The electron mobility along the [100] increase with tensile stress and decrease with compressive stress, while does the opposite for the electron mobility along the [010] and [001]. The electron mobility along the [100], [010] and [001] tend to saturate for stress beyond a certain level. The stress induced the reduction of conductivity effective mass and the suppression of inter-valley scattering rate are responsible for the enhancement of electron mobility. The calculated results provide valuable reference for the optimum stress and orientation of the conduction channel in the uniaxial strained Si nMOS devices design. The electron mobility calculated model used in the present work is suitable for implementation in TCAD simulators.

Electronic conductivity effective masses along arbitrary directional channel in uniaxial strained Si(001)

Electronic conductivity effective mass is one of the key parameters studing electron mobility enhancement in unixial strained Si material. Its in-depth study has the significant theoretical and practical values. In this paper, we first establish the E-k relation for conduction band in a unixial strained Si material. And the model of electronic conductivity effective mass along an arbitrary directional channel in the uniaxial strained Si (001) is obtained. Our concluding results are described as follows. 1) Tensile stress should be used to enhance electron mobility for unixial trained Si. 2) In the case of tensile stress application, both [110]/(001) and [100]/(001) directions are the desirable ones from the evaluation of electronic conductivity effective mass. And [110]/(001) direction should be preferable when the density of state effective mass is taken into consideration. 3) If [100] direction becomes the channel direction under [110]/(001) uniaxial strain, the further electron mobility enhancement will occur. The results above can provide valuable reference for the conduction channel design related to stress and orientation in the strained Si nMOS device.

Research on the capacitance-voltage characteristic of strained-silicon NMOS accumulation capacitor

Accumulation MOS capacitor is more linear than inversion MOS capacitor and is almost independent of the operation frequency. In this paper, we present first the formation mechanism of the plateau, observed in the C-V characteristic of the strained-Si NMOS capacitor, and then a physical model for strained-Si NMOS capacitor in accumulation region. The results from the model show to be in excellent agreement with the experimental data. The proposed model can provide valuable reference for the strained-Si device design, and is has been implemented in the software for extracting the parameter of strained-Si MOSFET.

Study of physically modeling for small-scaled strained Si nMOSFET

In this paper, quasi-2D threshold voltage model of strained Si nMOS with polycrystalline SiGe gate is established based on the Guass Law and its I-V character model is also built based on the current density equation. The influence of relevant parameter on threshold voltage is analyzed by numerical analysis, and the validity of the model is verified by device simulator.

Model of electronical conductivity effective mass of strained Si

Strained Si CMOS technology is one of the most advanced technologies in present day microelectronics. Electronical conductivity effective mass of strained Si is a key parameter to study electron mobility enhancement. Using K ·P method with the help of perturbation theory, dispersion relation near conduction band valley was determined, including the longitudinal and transverse masses. And then, electronical conductivity effective masses of strained Si on (001),(101) and (111) planes were obtained with respect to stress, splitting energy and directions. It was found that both the [100]and [010]directional electronical conductivity effective masses of strained Si/(001)Si1-xGex and the [010]directional one of strained Si/(101)Si1-xGex decrease with increasing Ge fraction or stress, and both values tend to be constant. The results provide valuable reference to the conduction channel design related to stress and orientation in the strained Si nMOS devices.

3D TCAD simulations of strained Si CMOS devices with silicon-based alloy stressors and stressed CESL

Stress distributions in the Si channel regions of silicon-based alloy source/drain and stressed silicon nitride liner NMOSFETs with various widths were studied using 3D TCAD simulations. For strained Si NMOS, drive current enhancement was found to be dominated by tensile stress along the transport direction ( S xx ), and compressive stress along the growth direction ( S zz ) in larger width devices. Stress along the width ( S yy ) was found to have the least effect on the drain current in the large width regime. The compressive stress along the vertical direction, perpendicular to the gate oxide ( S zz ), contributes significantly to drive current enhancement and cannot be neglected in NMOSFETs. For strained Si PMOS, it is found that S xx contributes most substantially to the improvement in drive current, while S zz contributes the least. In the narrow width regime S yy noticeably enhances drive current, contributing almost a quarter of the total gain.

Extraction of η parameter characterising μ eff against E eff curves in strained Si nMOS devices

The eta parameter characterising the mu eff (E eff ) curves in strained Si nMOS transistors is extracted for the first time. It is found that eta is about 45% higher than in unstrained devices. Therefore, using a standard eta value (0.5) instead of the real one implies underestimation of mobility at a high effective field and, in turn, systematic error in surface roughness determination in strained Si devices.

Improved Hot-Electron Reliability in Strained-Si nMOS

Strained-Si/relaxed-Si/sub 1-x/Ge/sub x/ structures provide a viable means of improving CMOS performance. For nMOS devices, the tensile strain in pseudomorphic Si on relaxed-Si/sub 1-x/Ge/sub x/ splits the six-fold degeneracy of the conduction band minimum, rendering increased electron mobility due to a lower in-plane effective mass and reduced intervalley scattering. In this paper, in addition to confirming enhanced performance for biaxial-strained-Si nMOS, we present hot-electron degradation characteristics for the first time, showing improvement over bulk Si.