A scalable and flexible ASIC CIM system distributed on UNIX workstations, ORCHARD , has been developed. It is designed from three viewpoints: (1) cost and TAT reduction in system construction, (2) flexibility in data management for quality control, and (3) precise and quick scheduling and effective lot tracking to control TAT for each lot. The concept of a "virtual machine" is introduced to connect equipment having various protocols to a host system. The virtual machine is automatically generated at an average automatic generation ratio of as high as 89%, which leads to a reduction in cost and TAT in system construction. Data for quality control is managed by changing flexibly the "data processing recipe." This recipe defines screen format, data collected from equipment, and data transfered from various databases. Precise scheduling of lots with various levels of priority is achieved by introducing a priority evaluation function, thereby reducing scheduling time to 1/20 that for manual scheduling.

An on-line scheduler for ASIC manufacturing line management has been developed. The parameters in the schedule models and the dynamic priority curve in the schedule algorithm were adjusted to obtain schedules well-suited to practical ASIC line management and control. The scheduler is connected to the user interface control module of our ASIC CIM system. In order to facilitate on-line scheduling, we clarify the performance requirements of the computer used for the scheduler with respect to the line scale. Using a current EWS, the scheduler can easily make a one-day schedule for a small-scale line with an annual throughput of less than 1,000 lots within 10 minutes. To cope with larger-scale lines, the multiple scheduling method allows schedules to be produced quickly and efficiently. Therefore, the scheduler can respond flexibly to changes in production plan and line resources and the control delivery date of each lot.