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An efficient algorithm is proposed for fast synthesis of low complexity model-based inverse lithography technology (ILT) and phase shift masks (PSM) to improve the resolution and pattern fidelity in optical microlithography. The patterns on the mask are transformed into frequency space using 2D discrete cosine transformation (DCT). The solution space is thus changed to frequency space from real space. By cutting off high frequency components in DC spectrum, the dimension of the solution space is greatly reduced. Using a gradient-based algorithm, we solve the inverse problem in incoherent and partial coherent imaging systems with binary, 6%EPSM and APSM mask. Good fidelity images are achieved.

The deep reactive ion etching process (DRIE) [] is a time multiplexed process where a fast chemical etching and a passivation processes are applied alternatively. It is very popular in surface micro-machined MEMS processing to obtain trench structures with high aspect ratios. The presence of a thin passivation layer makes it a very challenging process, especially for the three-dimensional simulation analysis. In this work we present a modeling approach for the simulation of DRIE processes. The model has been implemented in the three dimensional process simulation framework . When varying the etching / deposition cycles’ time ratios, the DRIE process shows three different regimes. These regimes are as well represented by the developed model. The simulation results obtained are compared with the corresponding REM images of trench etching experiments.

This paper presents the results of a comparison among five Monte Carlo device simulators for nano-scale MOSFETs. These models are applied to the simulation of the I–V characteristics of a 25 nm gate-length MOSFET representative of the high-performance transistor of the 65 nm technology node. Appreciable differences between the simulators are obtained in terms of simulated I. These differences are mainly related to different treatments of the ionized impurity scattering (IIS) and pinpoint a limitation of the available models for screening effects at very large carrier concentrations.

A rigorous surface roughness scattering model for ultrathin-body SOI MOSFETs is presented, which extends Ando’s model for bulk MOSFETs. The matrix element of the scattering potential includes a generalized Prange-Nee term and all the Coulomb interaction terms. Using this model, we study the effects of the silicon body thickness, effective field, and dielectric constant of the insulator on the roughness-limited low-field electron mobility in ultrathin-body SOI MOSFETs.

The Pauli principle, which limits the occupancy of a single state to one electron, is included in a deterministic solver for the Langevin-Boltzmann equation (LBE) based on a spherical harmonics expansion. The Newton-Raphson scheme for solving the nonlinear BE converges within a few steps and the increase in CPU time is less than a factor of ten. Even in the case of an extremely degenerate electron gas no numerical problems occur. The approach works well for transport and noise, and the Nyquist theorem is satisfied with high numerical precision at equilibrium. For electrons in bulk silicon a non-negligible impact of the Pauli principle is found only at very high electron densities.

Electron-phonon coupling is central to semiconductor transport simulation. It is often treated in the simple Fermi’s Golden Rule formulation, but even at modest fields, such as those commonly present in modern semiconductor devices, finite state lifetime effects become important. Such effects are treated formally by including self-energy in the scattering formulation [, ]. In order to make the problem more tractable, especially for efficient Monte Carlo simulation, various simplifying assumptions are made. The most common form is to assume a Lorentzian distribution. This assumption is well justified by perturbation theory, and is simple to calculate and implement. In the limit of infinite state life-time, it collapses to the energy-conserving delta function of the Fermi’s Golden Rule. On the other hand, when non-zero broadening is present, energy is no longer conserved, and this has been noted in some cases to lead to accumulated broadening []. Such accumulation of energy can lead to non-physical results and push the electron energy distribution into the hot electron regime. Our goal is to explore the reasons for this accumulation of energy and propose remedies which can be implemented in standard simulation tools.

A simple technique that can be implemented in the Monte Carlo (MC) simulation of transport in a quantum well is reported. The main difference between the proposed technique and existing methods is the use of three dimension momentum (3Dk) particles in the simulation of a quantum region. The use of 3Dk particles within a quantum well structure facilitates the MC simulation of transport in nanoscale devices which contain both the classical and quantum regions.

In industrial environments, numerical simulation has become an indispensable tool for the development and optimization of especially front-end processes. In order to remain useful for future technology nodes, process simulation has to follow and partly even anticipate paradigm shifts of state-of-the-art processes and new materials for future nanoelectronic devices. Within this article, the author presents his personal view of unsolved and upcoming issues that have to be addressed and solved in future.

1/ noise in MOSFETs under large-signal excitation, which is important in CMOS analog and RF circuits, is modeled as a perturbation in the semiconductor equations employing the oxide-trapping model. The oxide-trapping model for a MOSFET in periodic large-signal operation shows that 1/ noise reduces more than the small-signal noise model predicts as the gate OFF voltage decreases further below the threshold voltage.

The intrinsic parameter fluctuations induced by random discrete dopants (RDD) in nano-scaled MOSFETs are studied by applying the quantum mechanical approach. The increase of effective oxide thickness (EOT) by the quantum mechanical corrections generally makes gate controllability worse. However, as far as ultra thin body (UTB) devices, the increase of EOT improves gate controllability by suppressing leakage current because it reduces electrical body thickness by the constraint of the physical body thickness.