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Technology Computer-Aided Design (TCAD)
Technology Computer-Aided Design (TCAD) refers to using computer simulations to develop and optimize semiconductor processing technologies and devices. TCAD simulation tools solve fundamental, physical, partial differential equations, such as diffusion and transport equations for discretized geometries, representing the silicon wafer or the layer system in a semiconductor device. This deep physical approach gives TCAD simulation predictive accuracy.
Therefore, it is possible to substitute TCAD computer simulations for costly and time-consuming test wafer runs when developing and characterizing a new semiconductor device or technology.
TCAD simulations are used widely in the semiconductor industry. As technologies become more complex, the semiconductor industry relies increasingly more on TCAD to cut costs and speed up the research and development process. In addition, semiconductor manufacturers use TCAD for yield analysis, that is, monitoring, analyzing, and optimizing their IC process flows, as well as analyzing the impact of IC process variation.
TCAD consists of two main branches: process simulation and device simulation.
In process simulation, processing steps such as etching, deposition, ion implantation, thermal annealing, and oxidation are simulated based on physical equations, which govern the respective processing steps. The simulated part of the silicon wafer is discretized (meshed) and represented as a finite-element structure (see Figure 1).
For example, in the simulation of thermal annealing, complex diffusion equations for each dopant species are solved on this mesh. For oxidation simulations, the growth of silicon oxide is simulated taking into account the oxygen diffusion, the mechanical stresses at corners, and so on. TCAD consists of two main branches: process simulation and device simulation.