Andreas Hössinger

Parallelization of a Monte-Carlo ion implantation simulator for three-dimensional crystalline structures

The simulation of ion implantation using a Monte-Carlo method is one of the most time consuming tasks in process simulation, which makes it a first-order target for parallelization. We present a parallelization strategy for the Monte-Carlo ion implantation simulator MCIMPL based on the message passing interface (MPI), with an almost linear performance gain.

Development and performance analysis of real‐world applications for distributed and parallel architectures

Several large real‐world applications have been developed for distributed and parallel architectures. We examine two different program development approaches. First, the usage of a high‐level programming paradigm which reduces the time to create a parallel program dramatically but sometimes at the cost of a reduced performance; a source‐to‐source compiler, has been employed to automatically compile programs—written in a high‐level programming paradigm—into message passing codes. Second, a manual program development by using a low‐level programming paradigm—such as message passing—enables the programmer to fully exploit a given architecture at the cost of a time‐consuming and error‐prone effort. Performance tools play a central role in supporting the performance‐oriented development of applications for distributed and parallel architectures. SCALA—a portable instrumentation, measurement, and post‐execution performance analysis system for distributed and parallel programs—has been used to analyze and to guide the application development, by selectively instrumenting and measuring the code versions, by comparing performance information of several program executions, by computing a variety of important performance metrics, by detecting performance bottlenecks, and by relating performance information back to the input program. We show several experiments of SCALA when applied to real‐world applications. These experiments are conducted for a NEC Cenju‐4 distributed‐memory machine and a cluster of heterogeneous workstations and networks. Copyright

Parallelization of a Monte Carlo ion implantation simulator

We present a parallelization method based on message passing interface (MPI) for a Monte Carlo program for two-dimensional (2-D) and three-dimensional (3-D) simulation of ion implantations. We use a master-slave strategy where the master process synchronizes the slaves and performs the input-output operations, while the slaves perform the physical simulation. For this method the simulation domain is geometrically distributed among several CPUs which have to exchange only very little information during the simulation. Thereby, the communication overhead between the CPUs is kept so low that it has almost no influence on the performance gain even if a standard network of workstations is used instead of a massively parallel computer to perform the simulation. We have optimized the performance gain by identifying bottlenecks of this strategy when it is applied to arbitrary geometries consisting of various materials. This requires the application of different physical models within the simulation domain and makes it impossible to determine a reasonable domain distribution before starting the simulation. Due to a feedback between master and slaves by online performance measurements, we obtain an almost linear performance gain on a cluster of workstations with just slightly varying processor loads. Besides the increase in performance, the parallelization method also achieves a distribution of the required memory. This allows 3-D simulations on a cluster of workstations, where each single machines would not have enough memory to perform the simulation on its own.

Anisotropic Mesh Refinement for the Simulation of Three-Dimensional Semiconductor Manufacturing Processes

This paper presents an anisotropic adaptation strategy for three-dimensional unstructured tetrahedral meshes, which allows us to produce thin mostly anisotropic layers at the outside margin, i.e., the skin of an arbitrary meshed simulation domain. An essential task for any modern algorithm in the finite-element solution of partial differential equations, especially in the field of semiconductor process and device simulation, the major application is to provide appropriate resolution of the partial discretization mesh. The start-up conditions for semiconductor process and device simulations claim an initial mesh preparation that is performed by so-called Laplace refinement. The basic idea is to solve Laplaces equation on an initial coarse mesh with Dirichlet boundary conditions. Afterward, the gradient field is used to form an anisotropic metric that allows to refine the initial mesh based on tetrahedral bisection

A computationally efficient method for three-dimensional simulation of ion implantation

The high accuracy which is necessary for modern process simulation often requires the use of Monte-Carlo ion implantation simulation methods, with the disadvantage of very long simulation times especially for three-dimensional applications. In this work a new method for an accurate and CPU time efficient three-dimensional simulation of ion implantation is suggested. The approach is based on a combination of the algorithmic capabilities of fast analytical and the Monte-Carlo simulation methods.

Using Temporary Explicit Meshes for Direct Flux Calculation on Implicit Surfaces

Abstract We focus on a surface evolution problem where the surface is represented as a narrow-band level-set and the local surface speed is defined by a relation to the direct visibility of a source plane above the surface. A level-set representation of the surface can handle complex evolutions robustly and is therefore a frequently encountered choice. Ray tracing is used to compute the visibility of the source plane for each surface point. Commonly, rays are traced directly through the level-set and the already available (hierarchical) volume data structure is used to efficiently perform intersection tests. We present an approach that performs ray tracing on a temporarily generated explicit surface mesh utilizing modern hardware-tailored single precision ray tracing frameworks. We show that the overhead of mesh extraction and acceleration structure generation is compensated by the intersection performance for practical resolutions leading to an at least three times faster visibility calculation. We reveal the applicability of single precision ray tracing by attesting a sufficient angular resolution in conjunction with an integration method based on an up to twelve times subdivided icosahedron.

Using one-dimensional radiosity to model neutral particle flux in high aspect ratio holes

We present a computationally inexpensive one-dimensional method to model the neutral flux in high aspect ratio holes for three-dimensional plasma etching simulations. The benefit of our approach lies in the fact that the computational costs of a three-dimensional plasma etching simulation are, for the most part, determined by calculating the surface flux of the relevant species. We propose a one-dimensional radiosity model for the neutral flux by assuming an ideal cylindrical shape as well as ideal diffuse sources and surfaces. Our model reproduces the results obtained by a three-dimensional ray tracing simulation and is therefore suited to be used as a drop-in replacement for cylinder-like hole structures to speed up three-dimensional plasma etching simulations.

Modeling and Simulation of Electrical Activation of Acceptor-Type Dopants in Silicon Carbide

We propose an empirical model to predict electrical activation ratios of aluminium- and boron-implanted silicon carbide with respect to various annealing temperatures. The obtained parameters and model extensions are implemented into Silvaco’s Victory Process simulator to enable accurate predictions of post-implantation process steps. The thus augmented simulator is used for numerous simulations to evaluate the activation behavior of p-type dopants as well as for the full process simulation of a pn-junction SiC diode to extract the carrier and acceptor depth profiles and compare the results with experimental findings.

Direction dependent three-dimensional silicon carbide oxidation growth rate calculations

We propose a direction dependent interpolation method for silicon carbide oxidation growth rates and we compute these rates for three-dimensional simulations according to known growth rate values. Additionally, we analyze the temperature dependence of silicon carbide oxidation for different crystal directions. Our approach is an essential step towards highly accurate three-dimensional oxide growth simulations and helps to better understand the silicon carbide anisotropic nature and oxidation mechanism.

Three-dimensional growth rate modeling and simulation of silicon carbide thermal oxidation

We investigate the anisotropic behavior of dry and wet thermal oxidation of silicon carbide for which a high-accuracy three-dimensional simulation model is entirely missing. To bridge this gap, we propose a direction dependent interpolation method for computing oxidation growth rates for three-dimensional problems. We use our method together with available one-dimensional oxidation models to simulate three-dimensional crystal orientation dependent 4H- and 6H-SiC oxidation processes.