Technology CAD

Technology CAD (or Technology Computer Aided Design, or TCAD) is a branch of electronic design automation that models semiconductor fabrication and semiconductor device operation. The modeling of the fabrication is termed Process TCAD, while the modeling of the device operation is termed Device TCAD. Included are the modelling of process steps (such as diffusion and ion implantation), and modelling of the behavior of the electrical devices based on fundamental physics, such as the doping profiles of the devices. TCAD may also include the creation of compact models (such as the well known SPICE transistor models), which try to capture the electrical behavior of such devices but do not generally derive them from the underlying physics. (However, the SPICE simulator itself is usually considered as part of ECAD rather than TCAD.)

From the diagram on the right:

Technology files and design rules are essential building blocks of the integrated circuit design process. Their accuracy and robustness over process technology, its variability and the operating conditions of the IC — environmental, parasitic interactions and testing, including adverse conditions such as electro-static discharge — are critical in determining performance, yield and reliability. Development of these technology and design rule files involves an iterative process that crosses boundaries of technology and device development, product design and quality assurance. Modeling and simulation play a critical role in support of many aspects of this evolution process.

The goals of TCAD start from the physical description of integrated circuit devices, considering both the physical configuration and related device properties, and build the links between the broad range of physics and electrical behavior models that support circuit design. Physics-based modeling of devices, in distributed and lumped forms, is an essential part of the IC process development. It seeks to quantify the underlying understanding of the technology and abstract that knowledge to the device design level, including extraction of the key parameters that support circuit design and statistical metrology. Although the emphasis here is on Metal Oxide Semiconductor (MOS) transistors — the workhorse of the IC industry — it is useful to briefly overview the development history of the modeling tools and methodology that has set the stage for the present state-of-the-art.

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