Object-Oriented Approach in Re-Engineering: the STMicroelectronics manufacturing Model

Current manufacturing systems have a very structured production model, expecially when high complexity and precision is required, as in semiconductor devices manifacturing. In addition, rapid changes in both production and market requirements may occur, hence great flexibility is also essential. These goals, together with the requirement of both adding new features as well as removing some model limitations, often impose to re-engineer periodically existing models, reducing as much as possible the time-to-market of a new product. Re-engineering means first to create an abstract representation of the system (i.e. the abstract model) through a reverse engineering process, then this model is re-designed, keeping as much as possible a high abstraction, so great expandability can be assured, as well as fully exploiting personnel know-how, so it is possible to take advantage of their experience about the model. Updating a model generally also requires to improve existing applications, both re-writing software components as well as adding new features to existing components. In this paper, the current model used inside STMicroelectronics facilities to define production flow (the sequence of operations to be performed in order to make products) is considered. First, the model and its limitations are described, then introducing an updated, enhanced, object-oriented model, with aggregational and constitutional hierarchies used to model and classify all entities and with a flexible inheritance mechanism used to speed-up and improve the definition of a production flow. It is also considered which improvements are required on the existing applications, introducing an enhanced environment capable of supporting the enhanced model while preserving at the same time both technical and economic investments through avoiding radical changes in existing environment.