Improving Three-Dimensional Semiconductor Modeling through Layout and Process Flow Analysis
Constructive Solid Geometry (CSG) is a solid modeling technique widely used for the design of semiconductor devices. With the simulation domain subdivision algorithm presented in this paper, the minimal number of solid modeling operations is required in order to build a three-dimensional (3D) device structure. The algorithm is based on a drawing method which combines information on photolithographic masks into a color raster. In this way, solid modeling operations are performed only once on regions having the same color.
Multi-Dimensional TCAD: The PROMPT/DESSIS Approach
Designing new semiconductor devices for very large scale integrated circuits (VLSI) requires intensive use of process and device simulation tools to reduce development costs. However, valid device simulation results can only be achieved when a high geometrical modeling precision has been reached during the process simulation phase. Accurate finite element simulators embedded in a multi-dimensional process simulation environment help to fulfill this quality requirement. Since general-purpose three-dimensional (3D) process simulators are not yet available, a modern design environment combines solid modeling techniques with one-dimensional (1D) and two-dimensional (2D) finite element simulators. In this article we present a consistent and integrated process simulation environment that eases the characterization and optimization of semiconductor devices. The straightforward modeling in all three dimensions of an EEPROM cell illustrates the presented approach.
Variations common to the interplanetary magnetic field, the zonal atmospheric circulation and the earth's rotation
A study of the cyclic fluctuations in the earth's rotation, the geomagnetic field, the global atmospheric circulation and solar activity reveals the existence of 50-day and 120-day oscillations common to all. Our results, as well as the results obtained by radiometric measurements from the satellites Nimbus-7 and the Solar Maximum Mission (Wilson 1982; Pap 1985), suggest that their origin lies in the physical processes in the sun. The mechanism remains unexplained but from this work it follows that the role of the interplanetary magnetic field could very well be important.