Assembly of ''best-of-breed'' cluster tools from plug-and-play modules supplied by different equipment manufacturers is made possible by the standards set by the Semiconductor Equipment and Materials International (SEMI) Modular Equipment Standards Committee (MESC). By complying with the MESC standards specifying the interfaces to Individual cluster modules - services, messages, and mechanical interfaces - these modules can become interoperable. To achieve the flexibility required for application specific integrated circuit (ASIC) production, the MESC standard has been implemented in a cluster tool for our Intelligent Modular Fab (IMF) project (Table 1). This approach can benefit every level of the semiconductor industry, from R&D and production facilities to equipment suppliers and systems integrators, by increasing flexibility and reducing development and integration costs.