A new approach for making process and device simulation tools easier to use is presented. Described is an integrated CAD system for process design in which users select applications rather than tools. CAD simulation methodologies for each application are stored in an applications database and supported by automatic execution modules in the system. A database of "seed files" for initial process parameters are also provided. Both execution automation and the content in user interfaces are tailored to the chosen application to provide for an exceptionally simple and efficient interface, one that minimizes user learning requirements.

A new circuit simulation model is presented for impact ionization generated MOSFET substrate current. The model uses four parameters to accurately model substrate current over a wide range of device dimensions and operating voltages, including operation in the linear region. The model is able to model substrate currents from both heavily doped and lightly doped devices.