Reducing environmentally induced defects while maintaining productivity

In Semiconductor manufacturing we expect the cause of defects to be process or tool related. However, at recent technology nodes we find that defects can be caused by issues related to the wafers environment, such as processing of other wafers in the same tool or in the same carrier, or by seemingly innocuous actions. One result is the rapid proliferation of queue time restrictions and batching rules. In this work we show defects which are caused by the environment and several ways to reduce the sensitivity to environmental factors. Process and tool changes are found to eliminate yield detractors. We also present a work around that has helped to reduce the impact of queue time restrictions on cycle time.