Queue Time Sensitivity Analysis Methodology

Queue time (QT) between consecutive process-steps is one of the factors affecting the quality of current products in semiconductors industry. Identification of process steps with queue time sensitivity is not an easy and quick analysis, and it requires a high number of lots. An effective tool for a quick identification of sensitivity of a specific operation to a queue time was developed at Micron Israel and it is applied on production material. The algorithm calculates the average absolute delta of responses between consecutive step QTs, where a minimal value is accepted in steps with a linear correlation between the QT and the response. This calculation results in a snapshot of the impact of QT for specific responses, or failures modes, for the entire production line, where the step with minimal value of this parameter is easily detected. This algorithm was used on production material and indeed helped to detect a new QT dependency in specific process steps. The Queue Time Sensitivity Analysis (QTSA) algorithm is a novel methodology to detect correlation of QT in a single process step to a certain electrical EOL failure. It can be easily implemented in a fabrication site by the IT team. QTSA methodology is very efficient in detecting QT related issues and it can be used both in routine mode on baseline material and during significant elevation in EOL or in-line failures.