Monte Carlo calculations of fast secondary electron production have been performed with a hybrid model for the discrete and continuous energy-loss processes. The Moller theory was adopted for the differential inelastic scattering cross-section which determines the production rate of fast secondary electrons. The calculations were made for both a bulk polymethyl methacrylate (PMMA) sample and 4000-Å-thin films of PMMA (with and without a silicon substrate) at 10 and 20 keV. The new model is discussed and comparison made with results obtained from the old model, which is based on the continuous slowing down approximation of Bethe for energy loss and the screened Rutherford equation for elastic angular scattering. The new model predicts a larger absorbed energy density than the old model for an isolated line source exposure on a resist film. The consequences of this fast secondary electron contribution on the ultimate limit in electron lithography is discussed.

simulation procedure is developed for kilovolt electron beam scattering and energy loss in targets consisting of thin films on thick substrates. Such calculations have direct application to the nondestructive quantitative chemical analysis of ultrathin films in the electron microprobe (an electron probe x-ray microanalyzer), utilizing characteristic x-ray fluorescence. Angular elastic scattering is calculated in the electron trajectory simulation with the screened Rutherford expression for cross section, and energy loss between elastic scattering events is calculated with the continuous-slowing-down approximation of Bethe. The contribution to xray fluorescence from the film due to backscattered electrons from the substrate is accounted for. For elemental films, the Monte Carlo simulation predicts intensity ratios kt for characteristic x-rays from the film, referenced to standards of thick elemental samples. No film standards are required, and the mass thickness of any elemental film on any substrate can be determined from theoretical calibration curves. The model has been verified by measurements on films of Si, Cu, and Au on A J 0 3 over wide ranges in E, and t. For alloy films, calibration curves are generated and graphically iterated to provide independent analysis of weight fractions C i and total mass thickness p t. Films of Mn,Bi, and Co,Pt, were successfully analyzed with p t 5 100 pg/cm2.

In semiconductors having high efficiency for radiative recombination, the voltage dependence of cathodoluminescence may be used to determine the diffusion length and to estimate the surface recombination velocity of excess carriers. Theoretical calculations are based on a knowledge of the Laplace transform of the distribution of excitation with depth as determined from the target absorption correction in electron probe microanalysis or, alternatively, on a Gaussian approximation to the distribution of excitation with depth. Experimental results with accelerating voltages of 5–50 kV indicate values of diffusion length in n-type GaAs ranging from 3.0 μ at low-carrier concentration (5.1×1016 cm−3) to 0.65 μ at high-carrier concentration (3×1018 cm−3). The estimated accuracy for diffusion lengths between 0.5 and 4 μ is ±30%. Information is also obtained on the surface recombination velocity and the thickness of a ``dead layer'' at the surface.

While the selection of new "backbone" device structure in the era of post-planar CMOS is open to a few candidates, FinFET and its variants show great potential in scalability and manufacturability for nanoscale CMOS. In this paper we report the design, fabrication, performance, and integration issues of double-gate FinFET with the physical gate length being aggressively shrunk down to 10nm and the fin width down to 12nm. These MOSFETs are believed to be the smallest double-gate transistors ever fabricated. Excellent short-channel performance is observed in devices with a wide range of gate lengths (10~105nm). The subthreshold slopes of the 10nm gate length FinFETs are 125mV/dec for n-FET and 101mV/dec for p-FET, respectively. The DIBL's are 71mV/V for n-FET and 120mV/V for p-FET, respectively. At 55nm gate length, the subthreshold slopes are 64mV/dec for n-FET and 68mV/dec for p-FET, which is very close to the ideal MOSFET behavior (at room temperature). The DIBL's are 11mV/V for n-FET and 27mV/V for p-FET, respectively. All measurements were performed at a supply voltage of 1.2V. The observed short-channel behavior outperforms any reported single-gate silicon MOSFETs. Due to the (110) channel crystal orientation, hole mobility in the fabricated p-channel FinFET remarkably exceeds that in a traditional planar MOSFET. At 105nm gate length, pchannel FinFET shows a record-high transconductance of 633µS/µm at a V dd of 1.2V. At extremely small gate lengths, parasitic R sd in the narrow fin (proportionally scaled with L g ) influences the device performance. Working CMOS FinFET inverters are also demonstrated.