Analysis of Subthreshold Swing of Symmetric Junctionless Double Gate MOSFET Using Gaussian Doping Profile

—The variation of subthreshold swing(SS) according to the projected range (Rp ) and standard projected deviation (σp ) was analyzed when the symmetrical junctionless double gate (JLDG) MOSFET was doped with Gaussian doping profile. For this purpose, the analytical SS model was presented. We compared with the TCAD results to turn out the validity of this model, and the SSs of this model agreed with those of TCAD. The effective conduction path and mean doping concentration affecting the SS were analyzed according to the Rp and σp . As a result, the SS increased as the Rp and σp increased simultaneously. The smaller the Rp and the larger the σp , the lower the SS. When Rp = 1.5 nm, it showed the SS below 100mV/dec without being affected by the change of σp or silicon thickness. When σp = 3nm, it was also 100mV/dec or less regardless of the change of Rp and silicon thickness. Keywords— Double gate, Junctionless, Subthreshold swing, Gaussian, Projected range, Standard projected deviation

Cause analysis of width-dependence of on-current variability in thin gate-all-around silicon nanowire MOSFET

In this study, the width dependence of on-current variability in extremely narrow gate-all-around (GAA) silicon nanowire MOSFET down to 2nm width is analyzed by variability decomposition into components as well as analyzing the Pelgrom plot. It is found that the current variability rapidly increases below 4nm mainly due to quantum-effect-induced threshold voltage variability and silicon-thickness-fluctuation-induced mobility fluctuation (μfluctuation). The current variability becomes even worse in 2nm, which is fundamentally caused by line width roughness.

FIN Junctionless Field Effect Transistor (FIN-JLFET) With Ground Plane For Surpassing Parasitic BJT Action

The leakage mechanism due to lateral band-to-band tunneling (L-BTBT) results in increased off state current and hinders the scaling of the junctionless transistor. The effect of L-BTBT on FIN shaped gate Junctionless field effect transistor (JLFET) with the ground plane (GP) in oxide has been investigated. The proposed device is simulated using 3-D Silvaco TCAD and shows that it can mitigate the L-BTBT and leads to efficient volume depletion which relaxes the requirements of ultra-thin silicon thickness and high workfunction of the gate electrode. The results show significantly reduced OFF-state current and high Ion /Ioff ratio even at scaled gate length beyond 10 nm along with the reduction in drain induced barrier lowering and threshold voltage roll-off . Thus, the proposed device shows better performance at sub-10 nm node.

Relationship of drain induced barrier lowering and top/bottom gate oxide thickness in asymmetric junctionless double gate MOSFET

The relationship of drain induced barrier lowering (DIBL) phenomenon and channel length, silicon thickness, and thicknesses of top and bottom gate oxide films is derived for asymmetric junctionless double gate (JLDG) MOSFETs. The characteristics between the drain current and the gate voltage is derived by using the potential distribution model to propose in this paper. In this case, the threshold voltage is defined as the corresponding gate voltage when the drain current is (W/L) × 10-7 A, and the DIBL representing the change in the threshold voltage with respect to the drain voltage is obtained. As a result, we observe the DIBL is proportional to the negative third power of the channel length and the second power of the silicon thickness and linearly proportional to the geometric mean of the top and bottom gate oxide thicknesses, and derive a relation such as DIBL =25.15ηL_g^(-3) t_si^2 √(t_ox1∙t_ox2 ), where η is a static feedback coefficients between 0 and 1. The η is found to be between 0.5 and 1.0 in this model. The DIBL model of this paper has been observed to be in good agreement with the result of other paper, so it can be used in circuit simulation such as SPICE.

Laser Chemical Etching Trench Refinements for Backside Debug Journey to the Circuit Layer

The journey to the circuit layer will be described by first discussing baseline processes of laser assisted chemical etching (LACE) steps before the focused ion beam (FIB) workflow. These LACE processes take advantage of a dual 532 nm continuous wave (CW) and pulse laser system, however limitations and overhead that is transferred over to the FIB operator will be demonstrated. Experiments show an additional third 355 nm ultraviolet (UV) pulse laser process introduction into the workflow can further reduce the remaining silicon thickness (RST) relieving FIB overhead. In addition, complex pulse laser patterning techniques will show a refinement to nonuniform produced silicon. Finally, other pulse laser patterning techniques such as polygon etch capability will allow laser etching around and in-between features to enhance circuit layer accessibility for debug operations.

Backside Integrated Circuit Magnetic Field Imaging with a Quantum Diamond Microscope

We present a new method for backside integrated circuit (IC) magnetic field imaging using Quantum Diamond Microscope (QDM) nitrogen vacancy magnetometry. We demonstrate the ability to simultaneously image the functional activity of an IC thinned to 12 µm remaining silicon thickness over a wide fieldof- view (3.7 x 3.7 mm2). This 2D magnetic field mapping enables the localization of functional hot-spots on the die and affords the potential to correlate spatially delocalized transient activity during IC operation that is not possible with scanning magnetic point probes. We use Finite Element Analysis (FEA) modeling to determine the impact and magnitude of measurement artifacts that result from the specific chip package type. These computational results enable optimization of the measurements used to take empirical data yielding magnetic field images that are free of package-specific artifacts. We use machine learning to scalably classify the activity of the chip using the QDM images and demonstrate this method for a large data set containing images that are not possible to visually classify.

Temperature, Silicon Thickness and Intrinsic Length Influence on the Operation of Lateral SOI PIN Photodiodes

This work presents an analysis of the influence of the intrinsic length region (Li) and the thickness of the silicon film (tSi) on the performance of lateral thin-film SOI PIN photodiodes when illuminated by low wavelengths, in the blue and ultraviolet (UV) range. The experimental measurements performed with the wavelengths of 396 nm, 413 nm, and 460 nm in a temperature range of 100 K to 400 K showed that the optical responsivity of the SOI PIN photodetectors has larger dependence on the incident wavelength than on temperatures variation. Two-dimensional numerical simulations showed the same trends as the experimental results as a function of temperature and as a function of wavelength. Numerical simulations were used to investigate the responsivity and total quantum efficiency of PIN SOI photodetectors with intrinsic length region ranging from 5 µm to 30 µm and silicon film thickness ranging between 40 nm to 500 nm. From the results can be concluded that by properly choosing Li and tSi it is possible to optimize PIN SOI photodiodes performance for detecting specific wavelengths.

Subthreshold swing model using scale length for sub-10 nm junction-based double-gate MOSFETs

We propose an analytical model for subthreshold swing using scale length for sub-10 nm double gate (DG) MOSFETs. When the order of the calculation for the series type potential distribution is increased it is possible to obtain accuracy, but there is a problem that the calculation becomes large. Using only the first order calculation of potential distribution, we derive the scale length λ1 and use it to obtain an analytical model of subthreshold swing. The findings show this subthreshold swing model is in concordance with a 2D simulation. The relationship between the channel length and silicon thickness, which can analyze the subthreshold swing using λ1, is derived by the relationship between the scale length and the geometric mean of the silicon and oxide thickness. If the silicon thickness and oxide film thickness satisfy the condition of (Lg-0.215)/6.38 > tsi(=tox), it is found that the result of this model agrees with the results using higher order calculations, within a 4% error range.