Andreas Hössinger

Silvaco · TCAD - Process R&D

Alternatives to silicon for electronic devices for operation at high-power, high temperature, and in rough environments, are highly sought after. In particular, semiconductors with a wide bandgap and high breakdown field when compared to silicon, are desired. In particular, SiC and GaN have shown promise for these applications and are essential for...

Fluorocarbon dry etching of vertical silica-based structures is essential to the fabrication of advanced complementary metal-oxide-semiconductor and dynamic random access memory devices. However, the development of etching technology is challenged by the lack of understanding of complex surface reaction mechanisms and by the intricacy of etchant fl...

The level-set method is widely used in expanding front simulations in numerous fields of computational research, such as computer graphics, physics, or microelectronics. In the latter, the level-set method is employed for topography simulations of semiconductor device fabrication processes, being driven by complicated physical and chemical models....

Atomic layer deposition allows for precise control over film thickness and conformality. It is a critical enabler of high aspect ratio structures, such as 3D NAND memory, since its self-limiting behavior enables higher conformality than conventional processes. However, as the aspect ratio increases, deviations from complete conformality frequently...

Thin material layers are common structures in modern semiconductor device fabrication and are particularly necessary for light-emitting diodes and three-dimensional NAND memory devices. Such layers are not only deposited on the flat wafer surface but are also partially removed during subsequent etching steps. Level-set based process TCAD simulation...

Atomic layer deposition allows for precise control over film thickness and conformality. It is a critical enabler of high aspect ratio structures, such as 3D NAND memory, since its self-limiting behavior enables higher conformality than conventional processes. However, as the aspect ratio increases, deviations from ideal conformality frequently occ...

Low-bias etching of silicon (Si) using sulfur hexafluoride (SF6) plasma is a valuable tool in the manufacturing of electronic devices and micro electro-mechanical systems (MEMS). This kind of etching offers an almost isotropic etching behaviour, since the low voltage bias does not provide enough vertical acceleration and kinetic energy to the ions....

We present a feature detection method for adaptive grid refinement in hierarchical grids used in process technology computer-aided design topography simulations based on the local curvature of the wafer surface. The proposed feature detection method enables high-accuracy simulations whilst significantly reducing the run-time, because the grid is on...

The level-set method is widely used for high-accuracy 3-D topography simulations in process technology computer-aided design (TCAD) because of its robustness to topological changes introduced by the involved complicated physical phenomena. Particularly challenging are material flow processes, such as oxidation, reflow, and silicidation, as these re...

We present a continuum modeling approach to simulate anisotropic wet etching of single-crystal sapphire employing mixtures of sulfuric acid and phosphoric acid. Wet etching of sapphire leads to the formation of crystal facets with high Miller–Bravais indices. The resulting complex three-dimensional topographies can be exploited to optimize the patt...

The fast marching method is commonly used in expanding front simulations in various fields, such as, fluid dynamics, computer graphics, and in microelectronics, to restore the signed-distance field property of the level-set function, also known as re-distancing. To improve the performance of the re-distancing step, parallel algorithms for the fast...

Topography simulation is typically implemented with the level-set method which uses the level-set function to represent the interface. The signed-distance property, capturing the distances from the entire simulation domain towards the interface, has to be regularly restored during a simulation in order to update the distances relative to the evolut...

In etching and deposition simulations of a semiconductor fabrication process the calculation of the surface rates of particles is an essential but also the computationally most demanding step. A promising approach is to preprocess the simulation domain by simplifying the surface. We thus propose a new surface mesh simplification method that takes a...

We present numerical methods to enable accurate and robust level-set based simulation of anisotropic wet etching and non-planar epitaxy for semiconductor fabrication. These fabrication techniques are characterized by highly crystal orientation-dependent etch/growth rates, which lead to non-convex Hamiltonians in their description by the level-set e...

The level-set method is widely used to track the motion of interfaces driven by a velocity field. In many applications, the underlying physical model defines the velocity field only at the interface itself. For these applications, an extension of the velocity field to the simulation domain is required. This extension has to be performed in each tim...

A common problem arising in expanding front simulations is to restore the signed distance field property of a discretized domain (i.e., a mesh), by calculating the minimum distance of mesh points to an interface. This problem is referred to as re-distancing and a widely used method for its solution is the fast marching method (FMM). In many cases,...

Step-controlled growth of 4H-SiC epitaxial layers leads to the formation of a step-bunched morphology along the surface with larger macrosteps, composed of smaller microsteps of several Si-C bilayer heights. As thermal oxidation is an orientation-dependent process, a multi-faceted surface is expected to exhibit a different oxidation behavior compar...

A flexible and stretchable electronic device is an inevitable component to realize wearable and foldable display device. This requires high stability of backplane device operation on flexible substrate upon external mechanical stress such as bending, stretching, and other types of deformation induced stress. Because mechanical stress effects electr...

Technological control of doped regions is exceptionally important for all semiconductor devices. For the wide bandgap semiconductor silicon carbide, the activation state of dopants is determined by the postimplantation annealing step which consequently affects device operation and characteristics. We perform a detailed analysis of the effects of po...

Manufacturing integrated circuits was never a simple process. However, with scaling slowing down more significantly in the single digit nanometer regime due to skyrocketing fabrication costs the need for comparatively cheap simulation-based predictions has further increased. However, the necessary simulation tools in electronics and specifically in...

Process technology computer-aided design (TCAD) deals with simulating semiconductor device fabrication steps, such as etching and deposition, to enable computer-based device designs. The simulation backends are based on a variety of numerical methods, e.g., particle transport, surface advection, diffusion, and stress calculation, underlining the in...

The ongoing miniaturization in electronics poses various challenges in the designing of modern devices and also in the development and optimization of the corresponding fabrication processes. Computer simulations offer a cost- and time-saving possibility to investigate and optimize these fabrication processes. However, modern device designs require...

The development of novel electron devices requires a continuous support by process and device simulations in order to improve electrical properties and reduce production costs. However, an accurate description of the electrical properties of impurities in silicon carbide – a key wide bandgap semiconductor for power devices – is currently not availa...

A time-dependent modeling approach for electrical activation of implanted dopant species in semiconductors is currently missing, which limits the predictability of process simulations in technology computer-aided design. In this study we investigate the time-dependent electrical activation of phosphorus-implanted silicon carbide and propose a trans...

We focus on a surface evolution problem where the local surface speed depends on a computationally expensive scalar function with non-local properties. The local surface speed must be re-evaluated in each time step, even for non-moving parts of the surface, due to possibly changed properties in remote regions of the simulation domain. We present a...

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 augm...

Accurate modeling of the electrical properties of impurities in semiconductors is essential for the mandatory support of the development of novel semiconductor devices by means of simulations. An appropriate modeling approach to determine the activation rate of dopants in silicon carbide is currently not available, which limits the predictability o...

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...

We analyze the early stage of the highly-anisotropic silicon carbide oxidation behaviour with reactive force field molecular dynamics simulations. The oxidation of a-, C,- m-, and Si-crystallographic faces is studied at typical industry-focused temperatures in the range from 900 to 1200°C, based on the time evolution of the oxidation mechanism. The...

- A modeling approach for the electrical activation of implanted species in silicon carbide (SiC) is currently missing, which limits the predictability of process simulations. - We propose an empirical model to predict electrical activation ratios of aluminium (Al) and boron (B) implanted SiC. - The obtained parameters and model extensions are impl...

Typical p-type doping species in silicon carbide (SiC) are aluminium (Al) and boron (B), which are commonly implanted into the semiconductor. In order to increase the electrical activation of the implanted species, it is extremely important to perform thermal annealing as a post-implantation step. We have therefore investigated the post-implantatio...

- A modeling approach for the electrical activation of implanted species in silicon carbide (SiC) is currently missing, which limits the predictability of process simulations. - We propose an empirical model to predict electrical activation ratios of aluminium (Al) and boron (B) implanted SiC. - The obtained parameters and model extensions are impl...

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 augm...

We propose an empirical model to accurately predict electrical activation ratios of phosphorus and nitrogen implanted silicon carbide for arbitrary annealing temperatures. We introduce model parameters and compare the activation behaviour of the two donor-type dopants. Our investigations show that the activation ratio of the nitrogen implanted sili...

In numerical simulations of various areas of science and engineering, e.g., biomechanical engineering or ray tracing, the discretization of objects in physical space is an integral step. In particular for three-dimensional cases, where a volume mesh generation is required, the mesh generation is rather critical for the robustness, stability, and ac...

Semiconductor process simulation enables to predict critical manufacturing steps of semiconductor devices and circuits. In particular, it allows for so-called structure prototyping used in the critical exploratory phases of new semiconductor technologies. The ever-ongoing reduction of feature sizes and the required move towards increasingly intric...

Solving the eikonal equation allows to compute a monotone front propagation of anisotropic nature and is thus a widely applied technique in different areas of science and engineering. Various methods are available out of which only a subset is suitable for shared-memory parallelization, which is the key focus of this analysis. We evaluate three dif...

We investigate anisotropical and geometrical aspects of hexagonal structures of Silicon Carbide and propose a direction dependent interpolation method for oxidation growth rates. We compute three-dimensional oxidation rates and perform one-, two-, and three-dimensional simulations for 4H- and 6H-Silicon Carbide thermal oxidation. The rates of oxida...

We provide a full set of growth rate coefficients to enable high-accuracy two- and three-dimensional simulations of dry thermal oxidation of 4H-silicon carbide. The available models are insufficient for the simulation of complex multi-dimensional structures, as they are unable to predict oxidation for arbitrary crystal directions because of the ins...

We present a computationally efficient framework to compute the neutral flux in high aspect ratio structures during three-dimensional plasma etching simulations. The framework is based on a one-dimensional radiosity approach and is applicable to simulations of convex rotationally symmetric holes and convex symmetric trenches with a constant cross-s...

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 a...

● We propose a direction-dependent method for computing oxidation growth rates for three-dimensional simulations of silicon carbide (SiC). ● The method is used together with Massoud’s oxidation model to simulate three-dimensional, dry and wet, 6H- and 4H-SiC oxidation processes. ● This approach enables to better understand the anisotropic nature an...

We present a computationally inexpensive framework to compute the neutral flux in high aspect ratio structures during three-dimensional plasma etching simulations. It is based on a one-dimensional radiosity approach and is applicable to simulations of convex-shaped rotationally symmetrical holes and convex-shaped trenches of infinite length. The fr...

The fast marching method is used to compute a monotone front propagation of anisotropic nature by solving the eikonal equation. Due to the sequential nature of the original algorithm, parallel approaches presented so far were unconvincing. In this work, we introduce a shared-memory parallelization approach which is based on an overlapping domain de...

We investigate geometrical aspects of silicon carbide (SiC) and propose a direction dependent interpolation method for computing oxidation growth rates for three- dimensional simulations. Additionally, we analyze the temperature dependence of SiC oxidation for different crystal directions. Our approach is an essential step for highly accurate three...

1. Introduction We investigate geometrical aspects of silicon carbide (SiC) and propose a direction dependent interpolation method for computing oxidation growth rates for three-dimensional simulations. Additionally, we analyze the temperature dependence of SiC oxidation for different crystal directions. Our approach is an essential step for highly...

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 towa...

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 surfac...

The finite iterative method is compared to an industry-hardened fast marching method for accelerating the redistancing step essential for Level Set-based process simulations in the area of technology computer-aided design. We discuss our implementation of the finite iterative method and depict extensions to improve the method for process simulation...

We present a computational method for locally adapted conformal anisotropic tetrahedral mesh refinement. The element size is determined by an anisotropy function which is governed by an error estimation driven ruler according to an adjustable maximum error. Anisotropy in refinement is taken into account to reduce the amount of elements compared to...

We have extended our Monte Carlo ion implantation simulator for Si 1−x Ge x targets in order to analyze the applicability for advanced CMOS devices. The penetration depth of ion implanted dopants in relaxed SiGe is significantly reduced compared to pure silicon due to the larger nuclear and electronic stopping power. The successful calibra-tion for...

For the simulation of etching and deposition processes the cellular method is very popular, because of its high robustness compared to alternative methods like the level set or the moving boundary approach. We present a method for the simulation of topography processes based on the cellular method that overcomes the problem of loss of information w...

An essential task for any finite element method is to provide appropriate resolution of the mesh to resolve the initial solution. We present a computational method for anisotropic tetrahedral mesh refinement according to an adjustable discretization error. The initial attribute profile is given by an analytical function which is twice continously d...

The aim of this work is to model accurately the DRIE Bosch process used for the MEMS components fabrication. This modelling will permit, depending on the design, to obtain a 3D visualization of the substrate after etching and therefore foresee the real MEMS profile. Another objective is to determine, depending on the modelling accuracy, some proces...

Thin film fabrication processes for MEMS are characterized by a variety of different process technologies and materials. Unlike in microelectronics the MEMS fabrication process is in most cases application specific and therefore integral part of the application design. Discovering the correct combination of process steps, materials and process para...

The deep reactive ion etching process (DRIE) [1] 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 pro...

The paper presents a new approach to three-dimensional semiconductor process simulation that overcomes the problem of moving boundaries and mesh generation. Contrary to using unstructured meshes, the approach makes use of the level set method on fixed Cartesian meshes. A concept of multilayer structure is introduced to capture an arbitrary complex...

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 equa...

We report an experimental and simulation study for introducing Boron ions into high Ge content relaxed SiGe layers and into Ge wafers. The successful calibration of our Monte Carlo ion implantation simulator for this wide class of materials is demonstrated by comparing the pre- dicted Boron proles with SIMS data. The larger nuclear and electronic s...

We present a Monte Carlo simulation study for introducing boron ions into Ge in the energy range from 5 to 40 keV. The successful calibration of our ion implantation simulator for crystalline Ge is demonstrated by comparing the predicted boron profiles with SIMS measurements. The generation of point defects are calculated with a modified Kinchin-Pe...

A design model representing the relations between application specific fabrication processes and the structural design flow will be presented. Subsequently a MEMS process design, simulation and tracking system, called PROMENADE, is introduced. It allows the specification of processes for specific applications, the simulation and the tracking of the...

Abstract—Strain is recognized as one of the key technology features to increase the drive current in scaled MOS devices. We present a Monte Carlo simulation study for introducing dopants into a strained Si/Si 1-x Ge x system at very low energies. The lattice constant in the epitaxial growth direction of the biaxial tensile strained silicon layer is...

An algorithm for smoothing results of three-dimensional Monte Carlo ion implantation simulations and translating them from the grid used for the Monte Carlo simulation to an arbitrary unstructured three-dimensional grid is pre- sented. This algorithm is important for joining various process simulation steps, where data has to be smoothed or transla...

We demonstrate the applicability of three-dimensional process simulation and show its benefit for the development of modern semiconductor technology. Therefore we have performed a process simulation for a Cay wood-EEPROM memory cell, followed by the extraction of the coupling capacitance. Such a kind of analysis allows to optimize the layout of the...

We present a computational method for three-dimensional tetrahedral mesh refinement according to the demands of oxidation simulation. The main focus lies on two major problems. First, the start-up condition of oxidation claims an initial mesh preparation which is done by the so called Laplace refinement, second the transient conversion of silicon (...

SiGe-based CMOS devices have significant performance enhancements compared to pure silicon devices. We have extended our Monte Carlo ion implantation simulator for Si1-xGex targets in order to study the formation of shallow junctions. SiGe has a larger nuclear and electronic stopping power for ion implanted dopants compared to pure silicon due to t...