Meshing / Explicit Dynamics

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conference time (CEST, Berlin)
Reliable Meshing of 10 000 Parts
28/10/2021 16:05 conference time (CEST, Berlin)
Room: A
M. Lautsch (Lautsch Finite Elemente GmbH, DEU)
M. Lautsch (Lautsch Finite Elemente GmbH, DEU)
We present a tetra mesher for multipart meshing purposes. The method is fully automated and rejects no parts if some simple rules are obeyed. The result is a ready to compute, conformal mesh for all parts and for the fluid outside. This method does not rely on Delaunay ideas but is based on wrapping-, segmentation- and marching volume techniques. At first we give a precise definition of what a part is. Starting with a special single tetra which covers the entire input geometry an adaptive refinement process creates a mesh which is fine near this geometry. This refinement process iterates the subdivision of the first tetra to eight tetras of the same shape and therefore of the same quality. This is just like in the cubic case. This division pattern is not applicable to arbitrary tetras, but for our starting one it works. The Marching Tetra method gives tetras which are assigned to parts. Since our mesh is conformal, imprints, i.e. triangles between tetras of different part-membership, can be derived easily. These imprints allow straight forward load definitions. We discuss the criteria which are necessary for mesh refinement and show how to achieve geometry correctness and good element quality simultaneously, by using edge- and face- collapse algorithms and by edge swapping methods. A special chapter is devoted to the generation of feature lines, i.e. sharp edges and lines where three parts meet. To treat feature points is an extension of this work. The Marching Tetra Multigrid method works for any number of parts. The input geometry must allow an answer to the question for any point, whether this point is inside or outside. If this point is inside for more than one part, we need a precise answer which part wins. This is the way Boolean subtract is performed automatically for overlapping parts. Some case studies of multipart problems are presented in the final section.
multipart meshing, marching Volume, wrapping, multigid, mesh improvement
conference time (CEST, Berlin)
Explicit Dynamic Analysis of Wafer Stage Cable Slab of EUV Lithography System
28/10/2021 16:25 conference time (CEST, Berlin)
Room: A
O. Khodko (ASML Netherlands B.V., NLD)
O. Khodko (ASML Netherlands B.V., NLD)
To produce microchips modern optical lithography systems are used. In an attempt to follow Moore’s law ASML is using extreme ultraviolet (EUV) light in their machines, which has a wavelength of only 13.5 nanometers. In EUV systems the wafer is rapidly moving inside a vacuum chamber where a blueprint of the chip is projected onto a silicon wafer with nanometer accuracy. To ensure that the wafer is at the right position at the right time, a position module is used. It’s connected to the base frame of the machine by means of a flexible connection called cable slab, which consists of cables for power and data, and hoses for transport of fluids and gasses. Because of high accelerations of the position module the cable slab behaves very dynamically. As a result, large deformations occur which might cause the cable slab to hit other parts inside the machine. Insufficient clamping force may also lead to slip between cables and brackets. This could result in damage or wear of the cable slab. Additionally, due to this dynamical behavior disturbance forces occur on the position module which negatively influence the positioning of the wafer. This article focuses on the prediction of the dynamic behavior of wafer stage cable slab in order to overcome existing issues and potentially minimize disturbance forces acting on the position module. To simulate complex non-linear dynamic behavior of cable slab at high operational speeds Altair RADIOSS explicit solver was used. For the propose of correct representation of cable slab’s behavior during different dynamic load cases, pre-loading of a system was performed by application of folding motion and gravity acceleration. Dynamic effects in these quasi-static load cases were minimized by using slow dynamic computation and energy discrete relaxation approaches to converge simulation towards static equilibrium. Following pre-loading steps, dynamic analysis of cable slab under various operating conditions was conducted. Proposed model allows fully describe the stress-stain state of cable slab at any given time and track its volume consumption during simultaneous movement of position module in two perpendicular directions, thus predict potential volume conflicts with surrounding parts. Knowledge about magnitude of contact forces at the interfaces allows to predict a wear of contacting parts. Disturbance forces on position module due to dynamic motion of cable slab also were investigated. Simulation shows a good level of correlation with experimental results obtained on test rig.
Semiconductor industry, microchips, cable slab, explicit analysis, RADIOSS, quasi-static load, dynamic load