Semiconductor process design: representations, tools, and methodologies

A vision of the future is presented in which the design of semiconductor fabrication processes is an integral part of the design of application specific circuits. The circuit designer (particularly of analog and microelectromechanical devices and circuits) will no longer be restricted to processing specification solely via layout and mask information, but will also directly specify process parameters, step sequences, and whole fabrication processes. For this vision to be realized, new approaches and software support systems are needed for both semiconductor process design and fabrication. This thesis focuses on the problem of semiconductor process design within the context of a comprehensive semiconductor CAD/CIM (computer-aided-design/computeraided manufacturing) approach. Three essential ingredients for the advancement of process design are here described. First, representations of the designed artifacts, specifically structures to be fabricated and fabrication processes, have been developed and adopted. This work contributes a prototype PIF (Profile Interchange Format) database to facilitate the uniform representation of wafer structures. A process flow representation (PFR) provides a representation of the process suitable for both design uses and fabrication. Based on these representations, new tools providing CAD capabilities beyond that of process simulation alone have been prototyped. A Simulation Manager provides uniform interfaces between the process flow and process simulators (Suprem-III and Simpl-2). Additional tools have been prototyped, including Process Advisors to provide help in process synthesis. Finally, methodologies for process design have been investigated, and the concept of "mutators" is troduced to aid in process integration. These representations, tools, and methodologies contribute toward the advancement of CAD/CIM systems that will be necessary to support the design and execution of application specific processes. Thesis Supervisor: Dimitri A. Antoniadis Title: Professor of Electrical Engineering and Computer Science