Abstract
The Burn--in test operations of a semiconductor manufacturer were studied with the objective of reducing the cycle time for processing lots of semiconductor chips introduced from the previous process step, and improving the uptime of the ovens used for testing. Lots consist of incompatible product families with different processing times and arrival times. Lots are pulled into the system based on when ovens become available. Lots also often have to be split for batch processing in ovens, due to capacity constraints of each oven. When a lot is split into multiple smaller lots, a split lot that finishes processing first waits for the last split lot of the same lot to finish processing, for the lot to be considered complete and made available for the next test process. Current schedule planning and implementation operations were studied and interviews with involved personnel were conducted. Additionally, data was extracted and analyzed from the company’s CAMSTAR database to analyze the past performance of the Burn--in test operations. Three main areas for improvements were analyzed and recommendations were made regarding each area. First, it is recommended that planners adopt the use of batching and sequencing heuristics in making weekly schedules. This gives them a holistic view of the week’s workload and a better way to schedule production lots, in addition to engineering tests and preventive maintenance. Second, the production line should make proper use of the company’s equipment status--tracking tool to carefully evaluate the times ovens become available and allocate batches immediately. This reduces idle time of ovens. Third, the production line should make more periodic line inspections monitoring system status and moving batches into available ovens. These recommendations combined together are expected to reduce the cycle time for lots to go through the Burn--in test operations by 4% and improve the uptime of ovens by 1%.