A standardized representation of process flow information forms the basis for process development, process optimization, process centering, and yield improvement, and facilitates process data exchange between TCAD groups and fabrication sites. Attempts to define a standardized vocabulary for representation and interchange of process flow information have met several challenges from the complexity of the physical processes and the variety of equipments and recipes in a rapidly evolving technology.
Boning and co-workers [BMPS92] propose a general semiconductor process modeling framework based on state and state transformation information of wafers, machines, and facilities, and aims at establishing a rigorous mathematical model for the interactions between material and equipment during processing.
The Berkeley Process Flow Language (BPFL) [WR87] [HRW90] provides a procedural description of the fabrication of semiconductor devices; it is based on COMMON LISP [Ste90a] and supports different views of a process sequence for different applications. Interpreters are used to translate a BPFL description into the appropriate format for a given tool or equipment.
Wenstrand [HRW90] presents an object-oriented approach to process flow representation, aiming at the integration of manufacturing, simulation, and design information.
The CAD Framework Initiative's Semiconductor Process Representation [GG91] [SG92] seeks to define an informational and procedural, generic and versatile model to capture all process-related information for semiconductor manufacturing.
Durbeck and co-workers [DCB93] focus on the capture and
management of fabrication
process information by means of objects organized in layers
corresponding to the equipment, step, process, and
flow views
The process specification system SPEC [KN95] employs a similar conceptual approach as [DCB93], subdividing process information into equipment, step, sequence, and wafer levels. Moreover, as part of the Microelectronics Manufacturing Science and Technology (MMST) program [BCDH94] [MHM94], it stresses concurrent engineering and revision control of process data items, and is also used for actual wafer processing.