The method can easily be adapted to describe the growth or etching process of any other crystal. AB - We present a method to describe the orientation dependence of the etch rate in anisotropic etching solutions of silicon, or any other single crystalline material, by analytical functions. 2 SIMULATION METHOD In the anisotropic wet chemical etching process, anisotropic etchants etch attack certain crystal planes much faster in one direction than in another direction. For the case of silicon, and planes etch at much higher rate than planes. This etch rate selectivity is used to create various cavity and groove. Sensors and Actuators A, 31(1992) 267 274 267 Anisotropic crystal etching: a simulation program J. Delapierre LET1/DOPTfSCMM-CEA -CENG 85X, 38041 Grenoble C dex (France) Abstract In the field of micro-devices, tools are actually needed to model the fabrication processes, especially the shapes resulting from chemical etching of a monocrystal. Anisotropic crystalline etching simulation (ACES) program based on a new continuous Cellular Automata (CA) model, which provides improved spatial resolutionand accuracy com-pared with the conventional and the stochastic CA methods. Implementation of a dynamic CA technique provides in-creased simulation speed and reduced memory requirement (5x). Anisotropic Crystalline Etching Simulation (ACES) software. Mechanical Engineering. Research output: Non-textual form › Software. Original language.
- Anisotropic Crystalline Etch Simulation Model
- Anisotropic Crystalline Etch Simulation Techniques
- Anisotropic Crystalline Etch Simulation Method
Bill Foote
EECS Department
University of California, Berkeley
Technical Report No. UCB/CSD-90-595
September 1990
http://www2.eecs.berkeley.edu/Pubs/TechRpts/1990/CSD-90-595.pdf
A series of programs have been developed to model anisotropic etching of crystalline substances. The focus of this work was on the computation of the geometric offset surfaces for a given object, when the etching of different faces progresses at different rates depending of face orientation. Programs have been developed to calculate the emerging shapes for both two- and three-dimensional geometries.
Since complete information about the anisotropic etch rates in all possible directions have been published for only very few combinations of crystals and etch solutions, we also had to write a rudimentary generator that would produce plausible and self-consistent direction-dependent etch rate functions. This modeling proceeds in stages: From the geometry of the crystal lattice, its atom spacings and angles between bonds, some inferences are made about the probability that certain more or less exposed atoms get attacked and removed by the etchant. With this model the etch rates for several key directions, i.e., for the simple crystallographic planes (100), (110), (210), (111), (211), and (221), have been calculated. The etch rates for the direction in between these key orientations are found by interpolation.
The etching simulator then uses such an artificially generated function or any function that may come from experimental observations and applies it to arbitrary polyhedral shapes. For all edges and vertices it first determines what new bevel faces might form because of strong local maxima and minima in the etch rate function. Then all the faces, the original ones as well as the bevel faces, are advanced at their corresponding etch rates and combined into a new consistent surface description of a solid object. The user can specify the total etching time and the number of intermediate states that should be displayed. The shapes obtained from the etching simulator programs are in good qualitative agreement with the kinds of shapes actually observed in the laboratory.
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1. IntroductionAnisotropic Crystalline Etch Simulation Model
